Implement destructuring assignments (#1406)

boa/src/bytecompiler.rs

@@ -1,6 +1,6 @@
 use crate::{
     syntax::ast::{
-        node::{GetConstField, GetField, Identifier, StatementList},
+        node::{Declaration, GetConstField, GetField, Identifier, StatementList},
         op::{AssignOp, BinOp, BitOp, CompOp, LogOp, NumOp, UnaryOp},
         Const, Node,
     },
@@ -588,35 +588,80 @@ impl ByteCompiler {
         match node {
             Node::VarDeclList(list) => {
                 for decl in list.as_ref() {
-                    let index = self.get_or_insert_name(decl.name());
+                    match decl {
-                    self.emit(Opcode::DefVar, &[index]);
+                        Declaration::Identifier { ident, .. } => {
-
+                            let index = self.get_or_insert_name(ident.as_ref());
-                    if let Some(expr) = decl.init() {
+                            self.emit(Opcode::DefVar, &[index]);
-                        self.compile_expr(expr, true);
+
-                        self.emit(Opcode::InitLexical, &[index]);
+                            if let Some(expr) = decl.init() {
-                    };
+                                self.compile_expr(expr, true);
+                                self.emit(Opcode::InitLexical, &[index]);
+                            };
+                        }
+                        Declaration::Pattern(pattern) => {
+                            for ident in pattern.idents() {
+                                let index = self.get_or_insert_name(ident);
+                                self.emit(Opcode::DefVar, &[index]);
+
+                                if let Some(expr) = decl.init() {
+                                    self.compile_expr(expr, true);
+                                    self.emit(Opcode::InitLexical, &[index]);
+                                };
+                            }
+                        }
+                    }
                 }
             }
             Node::LetDeclList(list) => {
                 for decl in list.as_ref() {
-                    let index = self.get_or_insert_name(decl.name());
+                    match decl {
-                    self.emit(Opcode::DefLet, &[index]);
+                        Declaration::Identifier { ident, .. } => {
-
+                            let index = self.get_or_insert_name(ident.as_ref());
-                    if let Some(expr) = decl.init() {
+                            self.emit(Opcode::DefLet, &[index]);
-                        self.compile_expr(expr, true);
+
-                        self.emit(Opcode::InitLexical, &[index]);
+                            if let Some(expr) = decl.init() {
-                    };
+                                self.compile_expr(expr, true);
+                                self.emit(Opcode::InitLexical, &[index]);
+                            };
+                        }
+                        Declaration::Pattern(pattern) => {
+                            for ident in pattern.idents() {
+                                let index = self.get_or_insert_name(ident);
+                                self.emit(Opcode::DefLet, &[index]);
+
+                                if let Some(expr) = decl.init() {
+                                    self.compile_expr(expr, true);
+                                    self.emit(Opcode::InitLexical, &[index]);
+                                };
+                            }
+                        }
+                    }
                 }
             }
             Node::ConstDeclList(list) => {
                 for decl in list.as_ref() {
-                    let index = self.get_or_insert_name(decl.name());
+                    match decl {
-                    self.emit(Opcode::DefConst, &[index]);
+                        Declaration::Identifier { ident, .. } => {
-
+                            let index = self.get_or_insert_name(ident.as_ref());
-                    if let Some(expr) = decl.init() {
+                            self.emit(Opcode::DefConst, &[index]);
-                        self.compile_expr(expr, true);
+
-                        self.emit(Opcode::InitLexical, &[index]);
+                            if let Some(expr) = decl.init() {
-                    };
+                                self.compile_expr(expr, true);
+                                self.emit(Opcode::InitLexical, &[index]);
+                            };
+                        }
+                        Declaration::Pattern(pattern) => {
+                            for ident in pattern.idents() {
+                                let index = self.get_or_insert_name(ident);
+                                self.emit(Opcode::DefConst, &[index]);
+
+                                if let Some(expr) = decl.init() {
+                                    self.compile_expr(expr, true);
+                                    self.emit(Opcode::InitLexical, &[index]);
+                                };
+                            }
+                        }
+                    }
                 }
             }
             Node::If(node) => {

boa/src/object/gcobject.rs

@@ -916,6 +916,77 @@ impl GcObject {
         // 16. Return desc.
         Ok(desc.build())
     }
+
+    /// `7.3.25 CopyDataProperties ( target, source, excludedItems )`
+    ///
+    /// More information:
+    ///  - [ECMAScript][spec]
+    ///
+    /// [spec]: https://tc39.es/ecma262/#sec-copydataproperties
+    #[inline]
+    pub fn copy_data_properties<K>(
+        &mut self,
+        source: &JsValue,
+        excluded_keys: Vec<K>,
+        context: &mut Context,
+    ) -> Result<()>
+    where
+        K: Into<PropertyKey>,
+    {
+        // 1. Assert: Type(target) is Object.
+        // 2. Assert: excludedItems is a List of property keys.
+        // 3. If source is undefined or null, return target.
+        if source.is_null_or_undefined() {
+            return Ok(());
+        }
+
+        // 4. Let from be ! ToObject(source).
+        let from = source
+            .to_object(context)
+            .expect("function ToObject should never complete abruptly here");
+
+        // 5. Let keys be ? from.[[OwnPropertyKeys]]().
+        // 6. For each element nextKey of keys, do
+        let excluded_keys: Vec<PropertyKey> = excluded_keys.into_iter().map(|e| e.into()).collect();
+        for key in from.own_property_keys() {
+            // a. Let excluded be false.
+            let mut excluded = false;
+
+            // b. For each element e of excludedItems, do
+            for e in &excluded_keys {
+                // i. If SameValue(e, nextKey) is true, then
+                if *e == key {
+                    // 1. Set excluded to true.
+                    excluded = true;
+                    break;
+                }
+            }
+            // c. If excluded is false, then
+            if !excluded {
+                // i. Let desc be ? from.[[GetOwnProperty]](nextKey).
+                let desc = from.__get_own_property__(&key);
+
+                // ii. If desc is not undefined and desc.[[Enumerable]] is true, then
+                if let Some(desc) = desc {
+                    if let Some(enumerable) = desc.enumerable() {
+                        if enumerable {
+                            // 1. Let propValue be ? Get(from, nextKey).
+                            let prop_value = from.__get__(&key, from.clone().into(), context)?;
+
+                            // 2. Perform ! CreateDataPropertyOrThrow(target, nextKey, propValue).
+                            self.create_data_property_or_throw(key, prop_value, context)
+                                .expect(
+                                    "CreateDataPropertyOrThrow should never complete abruptly here",
+                                );
+                        }
+                    }
+                }
+            }
+        }
+
+        // 7. Return target.
+        Ok(())
+    }
 }
 
 impl AsRef<GcCell<Object>> for GcObject {

boa/src/property/mod.rs

@@ -472,7 +472,7 @@ impl From<PropertyDescriptorBuilder> for PropertyDescriptor {
 /// - [ECMAScript reference][spec]
 ///
 /// [spec]: https://tc39.es/ecma262/#sec-ispropertykey
-#[derive(Trace, Finalize, Debug, Clone)]
+#[derive(Trace, Finalize, PartialEq, Debug, Clone)]
 pub enum PropertyKey {
     String(JsString),
     Symbol(JsSymbol),

boa/src/syntax/ast/node/declaration/mod.rs

@@ -1,5 +1,6 @@
 //! Declaration nodes
 use crate::{
+    builtins::{iterable::get_iterator, Array},
     environment::lexical_environment::VariableScope,
     exec::Executable,
     gc::{Finalize, Trace},
@@ -101,32 +102,66 @@ impl Executable for DeclarationList {
                 None => JsValue::undefined(),
             };
 
-            if self.is_var() && context.has_binding(decl.name()) {
+            match &decl {
-                if decl.init().is_some() {
+                Declaration::Identifier { ident, init } => {
-                    context.set_mutable_binding(decl.name(), val, true)?;
+                    if self.is_var() && context.has_binding(ident.as_ref()) {
+                        if init.is_some() {
+                            context.set_mutable_binding(ident.as_ref(), val, true)?;
+                        }
+                        continue;
+                    }
+
+                    match &self {
+                        Const(_) => context.create_immutable_binding(
+                            ident.to_string(),
+                            false,
+                            VariableScope::Block,
+                        )?,
+                        Let(_) => context.create_mutable_binding(
+                            ident.to_string(),
+                            false,
+                            VariableScope::Block,
+                        )?,
+                        Var(_) => context.create_mutable_binding(
+                            ident.to_string(),
+                            false,
+                            VariableScope::Function,
+                        )?,
+                    }
+
+                    context.initialize_binding(ident.as_ref(), val)?;
                 }
-                continue;
+                Declaration::Pattern(p) => {
-            }
+                    for (ident, value) in p.run(None, context)? {
+                        if self.is_var() && context.has_binding(ident.as_ref()) {
+                            if !value.is_undefined() {
+                                context.set_mutable_binding(ident.as_ref(), value, true)?;
+                            }
+                            continue;
+                        }
 
-            match &self {
+                        match &self {
-                Const(_) => context.create_immutable_binding(
+                            Const(_) => context.create_immutable_binding(
-                    decl.name().to_owned(),
+                                ident.to_string(),
-                    false,
+                                false,
-                    VariableScope::Block,
+                                VariableScope::Block,
-                )?,
+                            )?,
-                Let(_) => context.create_mutable_binding(
+                            Let(_) => context.create_mutable_binding(
-                    decl.name().to_owned(),
+                                ident.to_string(),
-                    false,
+                                false,
-                    VariableScope::Block,
+                                VariableScope::Block,
-                )?,
+                            )?,
-                Var(_) => context.create_mutable_binding(
+                            Var(_) => context.create_mutable_binding(
-                    decl.name().to_owned(),
+                                ident.to_string(),
-                    false,
+                                false,
-                    VariableScope::Function,
+                                VariableScope::Function,
-                )?,
+                            )?,
-            }
+                        }
-
+
-            context.initialize_binding(decl.name(), val)?;
+                        context.initialize_binding(ident.as_ref(), value)?;
+                    }
+                }
+            }
         }
 
         Ok(JsValue::undefined())
@@ -188,44 +223,841 @@ impl From<Declaration> for Box<[Declaration]> {
     }
 }
 
-/// Individual declaration.
+/// Declaration represents either an individual binding or a binding pattern.
+///
+/// For `let` and `const` declarations this type represents a [LexicalBinding][spec1]
+///
+/// For `var` declarations this type represents a [VariableDeclaration][spec2]
+///
+/// More information:
+///  - [ECMAScript reference: 14.3 Declarations and the Variable Statement][spec3]
+///
+/// [spec1]: https://tc39.es/ecma262/#prod-LexicalBinding
+/// [spec2]: https://tc39.es/ecma262/#prod-VariableDeclaration
+/// [spec3]:  https://tc39.es/ecma262/#sec-declarations-and-the-variable-statement
 #[cfg_attr(feature = "deser", derive(Serialize, Deserialize))]
 #[derive(Clone, Debug, Trace, Finalize, PartialEq)]
-pub struct Declaration {
+pub enum Declaration {
-    name: Identifier,
+    Identifier {
-    init: Option<Node>,
+        ident: Identifier,
+        init: Option<Node>,
+    },
+    Pattern(DeclarationPattern),
 }
 
 impl fmt::Display for Declaration {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Display::fmt(&self.name, f)?;
+        match &self {
-        if let Some(ref init) = self.init {
+            Self::Identifier { ident, init } => {
-            write!(f, " = {}", init)?;
+                fmt::Display::fmt(&ident, f)?;
+                if let Some(ref init) = &init {
+                    write!(f, " = {}", init)?;
+                }
+            }
+            Self::Pattern(pattern) => {
+                fmt::Display::fmt(&pattern, f)?;
+            }
         }
         Ok(())
     }
 }
 
 impl Declaration {
-    /// Creates a new variable declaration.
+    /// Creates a new variable declaration with a BindingIdentifier.
-    pub(in crate::syntax) fn new<N, I>(name: N, init: I) -> Self
+    #[inline]
+    pub(in crate::syntax) fn new_with_identifier<N, I>(ident: N, init: I) -> Self
     where
         N: Into<Identifier>,
         I: Into<Option<Node>>,
     {
-        Self {
+        Self::Identifier {
-            name: name.into(),
+            ident: ident.into(),
             init: init.into(),
         }
     }
 
-    /// Gets the name of the variable.
+    /// Creates a new variable declaration with an ObjectBindingPattern.
-    pub fn name(&self) -> &str {
+    #[inline]
-        self.name.as_ref()
+    pub(in crate::syntax) fn new_with_object_pattern<I>(
+        bindings: Vec<BindingPatternTypeObject>,
+        init: I,
+    ) -> Self
+    where
+        I: Into<Option<Node>>,
+    {
+        Self::Pattern(DeclarationPattern::Object(DeclarationPatternObject::new(
+            bindings,
+            init.into(),
+        )))
+    }
+
+    /// Creates a new variable declaration with an ArrayBindingPattern.
+    #[inline]
+    pub(in crate::syntax) fn new_with_array_pattern<I>(
+        bindings: Vec<BindingPatternTypeArray>,
+        init: I,
+    ) -> Self
+    where
+        I: Into<Option<Node>>,
+    {
+        Self::Pattern(DeclarationPattern::Array(DeclarationPatternArray::new(
+            bindings,
+            init.into(),
+        )))
+    }
+
+    /// Gets the initialization node for the declaration, if any.
+    #[inline]
+    pub(crate) fn init(&self) -> Option<&Node> {
+        match &self {
+            Self::Identifier { init, .. } => init.as_ref(),
+            Self::Pattern(pattern) => pattern.init(),
+        }
+    }
+}
+
+/// DeclarationPattern represents an object or array binding pattern.
+///
+/// This enum mostly wraps the functionality of the specific binding pattern types.
+///
+/// More information:
+///  - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - BindingPattern][spec1]
+///
+/// [spec1]: https://tc39.es/ecma262/#prod-BindingPattern
+#[cfg_attr(feature = "deser", derive(Serialize, Deserialize))]
+#[derive(Clone, Debug, Trace, Finalize, PartialEq)]
+pub enum DeclarationPattern {
+    Object(DeclarationPatternObject),
+    Array(DeclarationPatternArray),
+}
+
+impl fmt::Display for DeclarationPattern {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match &self {
+            DeclarationPattern::Object(o) => {
+                fmt::Display::fmt(o, f)?;
+            }
+            DeclarationPattern::Array(a) => {
+                fmt::Display::fmt(a, f)?;
+            }
+        }
+        Ok(())
+    }
+}
+
+impl DeclarationPattern {
+    /// Initialize the values of an object/array binding pattern.
+    ///
+    /// This function only calls the specific initialization function for either the object or the array binding pattern.
+    /// For specific documentation and references to the ECMAScript spec, look at the called initialization functions.
+    #[inline]
+    pub(in crate::syntax) fn run(
+        &self,
+        init: Option<JsValue>,
+        context: &mut Context,
+    ) -> Result<Vec<(Box<str>, JsValue)>> {
+        match &self {
+            DeclarationPattern::Object(pattern) => pattern.run(init, context),
+            DeclarationPattern::Array(pattern) => pattern.run(init, context),
+        }
+    }
+
+    /// Gets the list of identifiers declared by the binding pattern.
+    ///
+    /// A single binding pattern may declare 0 to n identifiers.
+    #[inline]
+    pub fn idents(&self) -> Vec<&str> {
+        match &self {
+            DeclarationPattern::Object(pattern) => pattern.idents(),
+            DeclarationPattern::Array(pattern) => pattern.idents(),
+        }
     }
 
-    /// Gets the initialization node for the variable, if any.
+    /// Gets the initialization node for the binding pattern, if any.
+    #[inline]
     pub fn init(&self) -> Option<&Node> {
+        match &self {
+            DeclarationPattern::Object(pattern) => pattern.init(),
+            DeclarationPattern::Array(pattern) => pattern.init(),
+        }
+    }
+}
+
+/// DeclarationPatternObject represents an object binding pattern.
+///
+/// This struct holds a list of bindings, and an optional initializer for the binding pattern.
+///
+/// More information:
+///  - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - ObjectBindingPattern][spec1]
+///
+/// [spec1]: https://tc39.es/ecma262/#prod-ObjectBindingPattern
+#[cfg_attr(feature = "deser", derive(Serialize, Deserialize))]
+#[derive(Clone, Debug, Trace, Finalize, PartialEq)]
+pub struct DeclarationPatternObject {
+    bindings: Vec<BindingPatternTypeObject>,
+    init: Option<Node>,
+}
+
+impl fmt::Display for DeclarationPatternObject {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt("{", f)?;
+        for (i, binding) in self.bindings.iter().enumerate() {
+            if i == self.bindings.len() - 1 {
+                write!(f, "{} ", binding)?;
+            } else {
+                write!(f, "{},", binding)?;
+            }
+        }
+        fmt::Display::fmt("}", f)?;
+        if let Some(ref init) = self.init {
+            write!(f, " = {}", init)?;
+        }
+        Ok(())
+    }
+}
+
+impl DeclarationPatternObject {
+    /// Create a new object binding pattern.
+    #[inline]
+    pub(in crate::syntax) fn new(
+        bindings: Vec<BindingPatternTypeObject>,
+        init: Option<Node>,
+    ) -> Self {
+        Self { bindings, init }
+    }
+
+    /// Gets the initialization node for the object binding pattern, if any.
+    #[inline]
+    pub(in crate::syntax) fn init(&self) -> Option<&Node> {
         self.init.as_ref()
     }
+
+    /// Initialize the values of an object binding pattern.
+    ///
+    /// More information:
+    ///  - [ECMAScript reference: 8.5.2 Runtime Semantics: BindingInitialization][spec1]
+    ///  - [ECMAScript reference:14.3.3.3 Runtime Semantics: KeyedBindingInitialization][spec2]
+    ///  - [ECMAScript reference:14.3.3.2 Runtime Semantics: RestBindingInitialization][spec3]
+    ///
+    /// [spec1]: https://tc39.es/ecma262/#sec-runtime-semantics-bindinginitialization
+    /// [spec2]: https://tc39.es/ecma262/#sec-runtime-semantics-keyedbindinginitialization
+    /// [spec3]:  https://tc39.es/ecma262/#sec-destructuring-binding-patterns-runtime-semantics-restbindinginitialization
+    pub(in crate::syntax) fn run(
+        &self,
+        init: Option<JsValue>,
+        context: &mut Context,
+    ) -> Result<Vec<(Box<str>, JsValue)>> {
+        let value = if let Some(value) = init {
+            value
+        } else if let Some(node) = &self.init {
+            node.run(context)?
+        } else {
+            JsValue::undefined()
+        };
+
+        if value.is_null() {
+            return Err(context.construct_type_error("Cannot destructure 'null' value"));
+        }
+        if value.is_undefined() {
+            return Err(context.construct_type_error("Cannot destructure 'undefined' value"));
+        }
+
+        // 1. Perform ? RequireObjectCoercible(value).
+        let value = value.require_object_coercible(context)?;
+        let mut results = Vec::new();
+
+        // 2. Return the result of performing BindingInitialization for ObjectBindingPattern using value and environment as arguments.
+        for binding in &self.bindings {
+            use BindingPatternTypeObject::*;
+
+            match binding {
+                // ObjectBindingPattern : { }
+                Empty => {
+                    // 1. Return NormalCompletion(empty).
+                }
+                //  SingleNameBinding : BindingIdentifier Initializer[opt]
+                SingleName {
+                    ident,
+                    property_name,
+                    default_init,
+                } => {
+                    // 1. Let bindingId be StringValue of BindingIdentifier.
+                    // 2. Let lhs be ? ResolveBinding(bindingId, environment).
+
+                    // 3. Let v be ? GetV(value, propertyName).
+                    let mut v = value.get_field(property_name.as_ref(), context)?;
+
+                    // 4. If Initializer is present and v is undefined, then
+                    if let Some(init) = default_init {
+                        if v.is_undefined() {
+                            // TODO: a. not implemented yet:
+                            // a. If IsAnonymousFunctionDefinition(Initializer) is true, then
+                            // i. Set v to the result of performing NamedEvaluation for Initializer with argument bindingId.
+
+                            // b. Else,
+                            // i. Let defaultValue be the result of evaluating Initializer.
+                            // ii. Set v to ? GetValue(defaultValue).
+                            v = init.run(context)?;
+                        }
+                    }
+
+                    // 5. If environment is undefined, return ? PutValue(lhs, v).
+                    // 6. Return InitializeReferencedBinding(lhs, v).
+                    results.push((ident.clone(), v));
+                }
+                //  BindingRestProperty : ... BindingIdentifier
+                RestProperty {
+                    ident,
+                    excluded_keys,
+                } => {
+                    // 1. Let lhs be ? ResolveBinding(StringValue of BindingIdentifier, environment).
+
+                    // 2. Let restObj be ! OrdinaryObjectCreate(%Object.prototype%).
+                    let mut rest_obj = context.construct_object();
+
+                    // 3. Perform ? CopyDataProperties(restObj, value, excludedNames).
+                    rest_obj.copy_data_properties(value, excluded_keys.clone(), context)?;
+
+                    // 4. If environment is undefined, return PutValue(lhs, restObj).
+                    // 5. Return InitializeReferencedBinding(lhs, restObj).
+                    results.push((ident.clone(), rest_obj.into()));
+                }
+                //  BindingElement : BindingPattern Initializer[opt]
+                BindingPattern {
+                    ident,
+                    pattern,
+                    default_init,
+                } => {
+                    // 1. Let v be ? GetV(value, propertyName).
+                    let mut v = value.get_field(ident.as_ref(), context)?;
+
+                    // 2. If Initializer is present and v is undefined, then
+                    if let Some(init) = default_init {
+                        if v.is_undefined() {
+                            // a. Let defaultValue be the result of evaluating Initializer.
+                            // b. Set v to ? GetValue(defaultValue).
+                            v = init.run(context)?;
+                        }
+                    }
+
+                    // 3. Return the result of performing BindingInitialization for BindingPattern passing v and environment as arguments.
+                    results.append(&mut pattern.run(Some(v), context)?);
+                }
+            }
+        }
+
+        Ok(results)
+    }
+
+    /// Gets the list of identifiers declared by the object binding pattern.
+    #[inline]
+    pub(in crate::syntax) fn idents(&self) -> Vec<&str> {
+        let mut idents = Vec::new();
+
+        for binding in &self.bindings {
+            use BindingPatternTypeObject::*;
+
+            match binding {
+                Empty => {}
+                SingleName {
+                    ident,
+                    property_name: _,
+                    default_init: _,
+                } => {
+                    idents.push(ident.as_ref());
+                }
+                RestProperty {
+                    ident: property_name,
+                    excluded_keys: _,
+                } => {
+                    idents.push(property_name.as_ref());
+                }
+                BindingPattern {
+                    ident: _,
+                    pattern,
+                    default_init: _,
+                } => {
+                    for ident in pattern.idents() {
+                        idents.push(ident);
+                    }
+                }
+            }
+        }
+
+        idents
+    }
+}
+
+/// DeclarationPatternArray represents an array binding pattern.
+///
+/// This struct holds a list of bindings, and an optional initializer for the binding pattern.
+///
+/// More information:
+///  - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - ArrayBindingPattern][spec1]
+///
+/// [spec1]: https://tc39.es/ecma262/#prod-ArrayBindingPattern
+#[cfg_attr(feature = "deser", derive(Serialize, Deserialize))]
+#[derive(Clone, Debug, Trace, Finalize, PartialEq)]
+pub struct DeclarationPatternArray {
+    bindings: Vec<BindingPatternTypeArray>,
+    init: Option<Node>,
+}
+
+impl fmt::Display for DeclarationPatternArray {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt("[", f)?;
+        for (i, binding) in self.bindings.iter().enumerate() {
+            if i == self.bindings.len() - 1 {
+                match binding {
+                    BindingPatternTypeArray::Elision => write!(f, "{}, ", binding)?,
+                    _ => write!(f, "{} ", binding)?,
+                }
+            } else {
+                write!(f, "{},", binding)?;
+            }
+        }
+        fmt::Display::fmt("]", f)?;
+        if let Some(ref init) = self.init {
+            write!(f, " = {}", init)?;
+        }
+        Ok(())
+    }
+}
+
+impl DeclarationPatternArray {
+    /// Create a new array binding pattern.
+    #[inline]
+    pub(in crate::syntax) fn new(
+        bindings: Vec<BindingPatternTypeArray>,
+        init: Option<Node>,
+    ) -> Self {
+        Self { bindings, init }
+    }
+
+    /// Gets the initialization node for the array binding pattern, if any.
+    #[inline]
+    pub(in crate::syntax) fn init(&self) -> Option<&Node> {
+        self.init.as_ref()
+    }
+
+    /// Initialize the values of an array binding pattern.
+    ///
+    /// More information:
+    ///  - [ECMAScript reference: 8.5.2 Runtime Semantics: BindingInitialization][spec1]
+    ///  - [ECMAScript reference: 8.5.3 Runtime Semantics: IteratorBindingInitialization][spec2]
+    ///
+    /// [spec1]: https://tc39.es/ecma262/#sec-runtime-semantics-bindinginitialization
+    /// [spec2]: https://tc39.es/ecma262/#sec-runtime-semantics-iteratorbindinginitialization
+    pub(in crate::syntax) fn run(
+        &self,
+        init: Option<JsValue>,
+        context: &mut Context,
+    ) -> Result<Vec<(Box<str>, JsValue)>> {
+        let value = if let Some(value) = init {
+            value
+        } else if let Some(node) = &self.init {
+            node.run(context)?
+        } else {
+            JsValue::undefined()
+        };
+
+        if value.is_null() {
+            return Err(context.construct_type_error("Cannot destructure 'null' value"));
+        }
+        if value.is_undefined() {
+            return Err(context.construct_type_error("Cannot destructure 'undefined' value"));
+        }
+
+        // 1. Let iteratorRecord be ? GetIterator(value).
+        let iterator = get_iterator(context, value)?;
+        let mut result = Vec::new();
+
+        // 2. Let result be IteratorBindingInitialization of ArrayBindingPattern with arguments iteratorRecord and environment.
+        for binding in &self.bindings {
+            use BindingPatternTypeArray::*;
+
+            match binding {
+                // ArrayBindingPattern : [ ]
+                Empty => {
+                    // 1. Return NormalCompletion(empty).
+                }
+                // ArrayBindingPattern : [ Elision ]
+                // Note: This captures all elisions due to our representation of a the binding pattern.
+                Elision => {
+                    // 1. If iteratorRecord.[[Done]] is false, then
+                    // a. Let next be IteratorStep(iteratorRecord).
+                    // b. If next is an abrupt completion, set iteratorRecord.[[Done]] to true.
+                    // c. ReturnIfAbrupt(next).
+                    // d. If next is false, set iteratorRecord.[[Done]] to true.
+                    let _ = iterator.next(context)?;
+
+                    // 2. Return NormalCompletion(empty).
+                }
+                // SingleNameBinding : BindingIdentifier Initializer[opt]
+                SingleName {
+                    ident,
+                    default_init,
+                } => {
+                    // 1. Let bindingId be StringValue of BindingIdentifier.
+                    // 2. Let lhs be ? ResolveBinding(bindingId, environment).
+
+                    let next = iterator.next(context)?;
+
+                    // 3. If iteratorRecord.[[Done]] is false, then
+                    // 4. If iteratorRecord.[[Done]] is true, let v be undefined.
+                    let mut v = if !next.is_done() {
+                        // a. Let next be IteratorStep(iteratorRecord).
+                        // b. If next is an abrupt completion, set iteratorRecord.[[Done]] to true.
+                        // c. ReturnIfAbrupt(next).
+                        // d. If next is false, set iteratorRecord.[[Done]] to true.
+                        // e. Else,
+                        // i. Let v be IteratorValue(next).
+                        // ii. If v is an abrupt completion, set iteratorRecord.[[Done]] to true.
+                        // iii. ReturnIfAbrupt(v).
+                        next.value()
+                    } else {
+                        JsValue::undefined()
+                    };
+
+                    // 5. If Initializer is present and v is undefined, then
+                    if let Some(init) = default_init {
+                        if v.is_undefined() {
+                            // TODO: a. not implemented yet:
+                            // a. If IsAnonymousFunctionDefinition(Initializer) is true, then
+                            // i. Set v to the result of performing NamedEvaluation for Initializer with argument bindingId.
+
+                            // b. Else,
+                            // i. Let defaultValue be the result of evaluating Initializer.
+                            // ii. Set v to ? GetValue(defaultValue).
+                            v = init.run(context)?
+                        }
+                    }
+
+                    // 6. If environment is undefined, return ? PutValue(lhs, v).
+                    // 7. Return InitializeReferencedBinding(lhs, v).
+                    result.push((ident.clone(), v));
+                }
+                // BindingElement : BindingPattern Initializer[opt]
+                BindingPattern { pattern } => {
+                    let next = iterator.next(context)?;
+
+                    // 1. If iteratorRecord.[[Done]] is false, then
+                    // 2. If iteratorRecord.[[Done]] is true, let v be undefined.
+                    let v = if !next.is_done() {
+                        // a. Let next be IteratorStep(iteratorRecord).
+                        // b. If next is an abrupt completion, set iteratorRecord.[[Done]] to true.
+                        // c. ReturnIfAbrupt(next).
+                        // d. If next is false, set iteratorRecord.[[Done]] to true.
+                        // e. Else,
+                        // i. Let v be IteratorValue(next).
+                        // ii. If v is an abrupt completion, set iteratorRecord.[[Done]] to true.
+                        // iii. ReturnIfAbrupt(v).
+                        Some(next.value())
+                    } else {
+                        None
+                    };
+
+                    // 3. If Initializer is present and v is undefined, then
+                    // a. Let defaultValue be the result of evaluating Initializer.
+                    // b. Set v to ? GetValue(defaultValue).
+
+                    // 4. Return the result of performing BindingInitialization of BindingPattern with v and environment as the arguments.
+                    result.append(&mut pattern.run(v, context)?);
+                }
+                // BindingRestElement : ... BindingIdentifier
+                SingleNameRest { ident } => {
+                    // 1. Let lhs be ? ResolveBinding(StringValue of BindingIdentifier, environment).
+                    // 2. Let A be ! ArrayCreate(0).
+                    // 3. Let n be 0.
+                    let a = Array::array_create(0, None, context)
+                        .expect("Array creation with 0 length should never fail");
+
+                    // 4. Repeat,
+                    loop {
+                        let next = iterator.next(context)?;
+                        // a. If iteratorRecord.[[Done]] is false, then
+                        // i. Let next be IteratorStep(iteratorRecord).
+                        // ii. If next is an abrupt completion, set iteratorRecord.[[Done]] to true.
+                        // iii. ReturnIfAbrupt(next).
+                        // iv. If next is false, set iteratorRecord.[[Done]] to true.
+
+                        // b. If iteratorRecord.[[Done]] is true, then
+                        if next.is_done() {
+                            // i. If environment is undefined, return ? PutValue(lhs, A).
+                            // ii. Return InitializeReferencedBinding(lhs, A).
+                            break result.push((ident.clone(), a.clone().into()));
+                        }
+
+                        // c. Let nextValue be IteratorValue(next).
+                        // d. If nextValue is an abrupt completion, set iteratorRecord.[[Done]] to true.
+                        // e. ReturnIfAbrupt(nextValue).
+
+                        // f. Perform ! CreateDataPropertyOrThrow(A, ! ToString(𝔽(n)), nextValue).
+                        // g. Set n to n + 1.
+                        Array::add_to_array_object(&a.clone().into(), &[next.value()], context)?;
+                    }
+                }
+                // BindingRestElement : ... BindingPattern
+                BindingPatternRest { pattern } => {
+                    // 1. Let A be ! ArrayCreate(0).
+                    // 2. Let n be 0.
+                    let a = Array::array_create(0, None, context)
+                        .expect("Array creation with 0 length should never fail");
+
+                    // 3. Repeat,
+                    loop {
+                        // a. If iteratorRecord.[[Done]] is false, then
+                        // i. Let next be IteratorStep(iteratorRecord).
+                        // ii. If next is an abrupt completion, set iteratorRecord.[[Done]] to true.
+                        // iii. ReturnIfAbrupt(next).
+                        // iv. If next is false, set iteratorRecord.[[Done]] to true.
+                        let next = iterator.next(context)?;
+
+                        // b. If iteratorRecord.[[Done]] is true, then
+                        if next.is_done() {
+                            // i. Return the result of performing BindingInitialization of BindingPattern with A and environment as the arguments.
+                            break result
+                                .append(&mut pattern.run(Some(a.clone().into()), context)?);
+                        }
+
+                        // c. Let nextValue be IteratorValue(next).
+                        // d. If nextValue is an abrupt completion, set iteratorRecord.[[Done]] to true.
+                        // e. ReturnIfAbrupt(nextValue).
+                        // f. Perform ! CreateDataPropertyOrThrow(A, ! ToString(𝔽(n)), nextValue).
+                        // g. Set n to n + 1.
+                        Array::add_to_array_object(&a.clone().into(), &[next.value()], context)?;
+                    }
+                }
+            }
+        }
+
+        // 3. If iteratorRecord.[[Done]] is false, return ? IteratorClose(iteratorRecord, result).
+        // 4. Return result.
+        Ok(result)
+    }
+
+    /// Gets the list of identifiers declared by the array binding pattern.
+    #[inline]
+    pub(in crate::syntax) fn idents(&self) -> Vec<&str> {
+        let mut idents = Vec::new();
+
+        for binding in &self.bindings {
+            use BindingPatternTypeArray::*;
+
+            match binding {
+                Empty => {}
+                Elision => {}
+                SingleName {
+                    ident,
+                    default_init: _,
+                } => {
+                    idents.push(ident.as_ref());
+                }
+                BindingPattern { pattern } | BindingPatternRest { pattern } => {
+                    let mut i = pattern.idents();
+                    idents.append(&mut i)
+                }
+                SingleNameRest { ident } => idents.push(ident),
+            }
+        }
+
+        idents
+    }
+}
+
+/// BindingPatternTypeObject represents the different types of bindings that an object binding pattern may contain.
+///
+/// More information:
+///  - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - ObjectBindingPattern][spec1]
+///
+/// [spec1]: https://tc39.es/ecma262/#prod-ObjectBindingPattern
+#[cfg_attr(feature = "deser", derive(Serialize, Deserialize))]
+#[derive(Clone, Debug, Trace, Finalize, PartialEq)]
+pub enum BindingPatternTypeObject {
+    /// Empty represents an empty object binding pattern e.g. `{ }`.
+    Empty,
+
+    /// SingleName represents one of the following properties:
+    ///
+    /// - `SingleNameBinding` with an identifier and an optional default initializer.
+    /// - `BindingProperty` with an property name and a `SingleNameBinding` as  the `BindingElement`.
+    ///
+    /// More information:
+    ///  - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - SingleNameBinding][spec1]
+    ///  - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - BindingProperty][spec2]
+    ///
+    /// [spec1]: https://tc39.es/ecma262/#prod-SingleNameBinding
+    /// [spec2]: https://tc39.es/ecma262/#prod-BindingProperty
+    SingleName {
+        ident: Box<str>,
+        property_name: Box<str>,
+        default_init: Option<Node>,
+    },
+
+    /// RestProperty represents a `BindingRestProperty` with an identifier.
+    ///
+    /// It also includes a list of the property keys that should be excluded from the rest,
+    /// because they where already assigned.
+    ///
+    /// More information:
+    ///  - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - BindingRestProperty][spec1]
+    ///
+    /// [spec1]: https://tc39.es/ecma262/#prod-BindingRestProperty
+    RestProperty {
+        ident: Box<str>,
+        excluded_keys: Vec<Box<str>>,
+    },
+
+    /// BindingPattern represents a `BindingProperty` with a `BindingPattern` as the `BindingElement`.
+    ///
+    /// Additionally to the identifier of the new property and the nested binding pattern,
+    /// this may also include an optional default initializer.
+    ///
+    /// More information:
+    ///  - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - BindingProperty][spec1]
+    ///
+    /// [spec1]: https://tc39.es/ecma262/#prod-BindingProperty
+    BindingPattern {
+        ident: Box<str>,
+        pattern: DeclarationPattern,
+        default_init: Option<Node>,
+    },
+}
+
+impl fmt::Display for BindingPatternTypeObject {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match &self {
+            BindingPatternTypeObject::Empty => {}
+            BindingPatternTypeObject::SingleName {
+                ident,
+                property_name,
+                default_init,
+            } => {
+                if ident == property_name {
+                    write!(f, " {}", ident)?;
+                } else {
+                    write!(f, " {} : {}", property_name, ident)?;
+                }
+                if let Some(ref init) = default_init {
+                    write!(f, " = {}", init)?;
+                }
+            }
+            BindingPatternTypeObject::RestProperty {
+                ident: property_name,
+                excluded_keys: _,
+            } => {
+                write!(f, " ... {}", property_name)?;
+            }
+            BindingPatternTypeObject::BindingPattern {
+                ident: property_name,
+                pattern,
+                default_init,
+            } => {
+                write!(f, " {} : {}", property_name, pattern)?;
+                if let Some(ref init) = default_init {
+                    write!(f, " = {}", init)?;
+                }
+            }
+        }
+        Ok(())
+    }
+}
+
+/// BindingPatternTypeArray represents the different types of bindings that an array binding pattern may contain.
+///
+/// More information:
+///  - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - ArrayBindingPattern][spec1]
+///
+/// [spec1]: https://tc39.es/ecma262/#prod-ArrayBindingPattern
+#[cfg_attr(feature = "deser", derive(Serialize, Deserialize))]
+#[derive(Clone, Debug, Trace, Finalize, PartialEq)]
+pub enum BindingPatternTypeArray {
+    /// Empty represents an empty array binding pattern e.g. `[ ]`.
+    ///
+    /// This may occur because the `Elision` and `BindingRestElement` in the first type of
+    /// array binding pattern are both optional.
+    ///
+    /// More information:
+    ///  - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - ArrayBindingPattern][spec1]
+    ///
+    /// [spec1]: https://tc39.es/ecma262/#prod-ArrayBindingPattern
+    Empty,
+
+    /// Elision represents the elision of an item in the array binding pattern.
+    ///
+    /// An `Elision` may occur at multiple points in the pattern and may be multiple elisions.
+    /// This variant strictly represents one elision. If there are multiple, this should be used multiple times.
+    ///
+    /// More information:
+    ///  - [ECMAScript reference: 13.2.4 Array Initializer - Elision][spec1]
+    ///
+    /// [spec1]: https://tc39.es/ecma262/#prod-Elision
+    Elision,
+
+    /// SingleName represents a `SingleNameBinding` with an identifier and an optional default initializer.
+    ///
+    /// More information:
+    ///  - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - SingleNameBinding][spec1]
+    ///
+    /// [spec1]: https://tc39.es/ecma262/#prod-SingleNameBinding
+    SingleName {
+        ident: Box<str>,
+        default_init: Option<Node>,
+    },
+
+    /// BindingPattern represents a `BindingPattern` in a `BindingElement` of an array binding pattern.
+    ///
+    /// The pattern and the optional default initializer are both stored in the DeclarationPattern.
+    ///
+    /// More information:
+    ///  - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - BindingElement][spec1]
+    ///
+    /// [spec1]: https://tc39.es/ecma262/#prod-BindingElement
+    BindingPattern { pattern: DeclarationPattern },
+
+    /// SingleNameRest represents a `BindingIdentifier` in a `BindingRestElement` of an array binding pattern.
+    ///
+    /// More information:
+    ///  - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - BindingRestElement][spec1]
+    ///
+    /// [spec1]: https://tc39.es/ecma262/#prod-BindingRestElement
+    SingleNameRest { ident: Box<str> },
+
+    /// SingleNameRest represents a `BindingPattern` in a `BindingRestElement` of an array binding pattern.
+    ///
+    /// More information:
+    ///  - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - BindingRestElement][spec1]
+    ///
+    /// [spec1]: https://tc39.es/ecma262/#prod-BindingRestElement
+    BindingPatternRest { pattern: DeclarationPattern },
+}
+
+impl fmt::Display for BindingPatternTypeArray {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match &self {
+            BindingPatternTypeArray::Empty => {}
+            BindingPatternTypeArray::Elision => {
+                fmt::Display::fmt(" ", f)?;
+            }
+            BindingPatternTypeArray::SingleName {
+                ident,
+                default_init,
+            } => {
+                write!(f, " {}", ident)?;
+                if let Some(ref init) = default_init {
+                    write!(f, " = {}", init)?;
+                }
+            }
+            BindingPatternTypeArray::BindingPattern { pattern } => {
+                write!(f, " {}", pattern)?;
+            }
+            BindingPatternTypeArray::SingleNameRest { ident } => {
+                write!(f, " ... {}", ident)?;
+            }
+            BindingPatternTypeArray::BindingPatternRest { pattern } => {
+                write!(f, " ... {}", pattern)?;
+            }
+        }
+        Ok(())
+    }
 }

boa/src/syntax/ast/node/declaration/tests.rs

@@ -39,3 +39,44 @@ fn fmt() {
         "#,
     );
 }
+
+#[test]
+fn fmt_binding_pattern() {
+    super::super::test_formatting(
+        r#"
+        var { } = {
+            o: "1",
+        };
+        var { o_v1 } = {
+            o_v1: "1",
+        };
+        var { o_v2 = "1" } = {
+            o_v2: "2",
+        };
+        var { a : o_v3 = "1" } = {
+            a: "2",
+        };
+        var { ... o_rest_v1 } = {
+            a: "2",
+        };
+        var { o_v4, o_v5, o_v6 = "1", a : o_v7 = "1", ... o_rest_v2 } = {
+            o_v4: "1",
+            o_v5: "1",
+        };
+        var [] = [];
+        var [ , ] = [];
+        var [ a_v1 ] = [1, 2, 3];
+        var [ a_v2, a_v3 ] = [1, 2, 3];
+        var [ a_v2, , a_v3 ] = [1, 2, 3];
+        var [ ... a_rest_v1 ] = [1, 2, 3];
+        var [ a_v4, , ... a_rest_v2 ] = [1, 2, 3];
+        var [ { a_v5 } ] = [{
+            a_v5: 1,
+        }, {
+            a_v5: 2,
+        }, {
+            a_v5: 3,
+        }];
+        "#,
+    );
+}

boa/src/syntax/ast/node/iteration/for_in_loop/mod.rs

@@ -6,7 +6,7 @@ use crate::{
     },
     exec::{Executable, InterpreterState},
     gc::{Finalize, Trace},
-    syntax::ast::node::Node,
+    syntax::ast::node::{Declaration, Node},
     BoaProfiler, Context, JsValue, Result,
 };
 use std::fmt;
@@ -130,15 +130,37 @@ impl Executable for ForInLoop {
                             return context.throw_syntax_error("a declaration in the head of a for-in loop can't have an initializer");
                         }
 
-                        if context.has_binding(var.name()) {
+                        match &var {
-                            context.set_mutable_binding(var.name(), next_result, true)?;
+                            Declaration::Identifier { ident, .. } => {
-                        } else {
+                                if context.has_binding(ident.as_ref()) {
-                            context.create_mutable_binding(
+                                    context.set_mutable_binding(
-                                var.name().to_owned(),
+                                        ident.as_ref(),
-                                false,
+                                        next_result,
-                                VariableScope::Function,
+                                        true,
-                            )?;
+                                    )?;
-                            context.initialize_binding(var.name(), next_result)?;
+                                } else {
+                                    context.create_mutable_binding(
+                                        ident.to_string(),
+                                        false,
+                                        VariableScope::Function,
+                                    )?;
+                                    context.initialize_binding(ident.as_ref(), next_result)?;
+                                }
+                            }
+                            Declaration::Pattern(p) => {
+                                for (ident, value) in p.run(Some(next_result), context)? {
+                                    if context.has_binding(ident.as_ref()) {
+                                        context.set_mutable_binding(ident.as_ref(), value, true)?;
+                                    } else {
+                                        context.create_mutable_binding(
+                                            ident.to_string(),
+                                            false,
+                                            VariableScope::Function,
+                                        )?;
+                                        context.initialize_binding(ident.as_ref(), value)?;
+                                    }
+                                }
+                            }
                         }
                     }
                     _ => {
@@ -153,12 +175,26 @@ impl Executable for ForInLoop {
                             return context.throw_syntax_error("a declaration in the head of a for-in loop can't have an initializer");
                         }
 
-                        context.create_mutable_binding(
+                        match &var {
-                            var.name().to_owned(),
+                            Declaration::Identifier { ident, .. } => {
-                            false,
+                                context.create_mutable_binding(
-                            VariableScope::Block,
+                                    ident.to_string(),
-                        )?;
+                                    false,
-                        context.initialize_binding(var.name(), next_result)?;
+                                    VariableScope::Block,
+                                )?;
+                                context.initialize_binding(ident.as_ref(), next_result)?;
+                            }
+                            Declaration::Pattern(p) => {
+                                for (ident, value) in p.run(Some(next_result), context)? {
+                                    context.create_mutable_binding(
+                                        ident.to_string(),
+                                        false,
+                                        VariableScope::Block,
+                                    )?;
+                                    context.initialize_binding(ident.as_ref(), value)?;
+                                }
+                            }
+                        }
                     }
                     _ => {
                         return context.throw_syntax_error(
@@ -172,12 +208,26 @@ impl Executable for ForInLoop {
                             return context.throw_syntax_error("a declaration in the head of a for-in loop can't have an initializer");
                         }
 
-                        context.create_immutable_binding(
+                        match &var {
-                            var.name().to_owned(),
+                            Declaration::Identifier { ident, .. } => {
-                            false,
+                                context.create_immutable_binding(
-                            VariableScope::Block,
+                                    ident.to_string(),
-                        )?;
+                                    false,
-                        context.initialize_binding(var.name(), next_result)?;
+                                    VariableScope::Block,
+                                )?;
+                                context.initialize_binding(ident.as_ref(), next_result)?;
+                            }
+                            Declaration::Pattern(p) => {
+                                for (ident, value) in p.run(Some(next_result), context)? {
+                                    context.create_immutable_binding(
+                                        ident.to_string(),
+                                        false,
+                                        VariableScope::Block,
+                                    )?;
+                                    context.initialize_binding(ident.as_ref(), value)?;
+                                }
+                            }
+                        }
                     }
                     _ => {
                         return context.throw_syntax_error(

boa/src/syntax/ast/node/iteration/for_of_loop/mod.rs

@@ -6,7 +6,7 @@ use crate::{
     },
     exec::{Executable, InterpreterState},
     gc::{Finalize, Trace},
-    syntax::ast::node::Node,
+    syntax::ast::node::{Declaration, Node},
     BoaProfiler, Context, JsValue, Result,
 };
 use std::fmt;
@@ -118,15 +118,37 @@ impl Executable for ForOfLoop {
                             return context.throw_syntax_error("a declaration in the head of a for-of loop can't have an initializer");
                         }
 
-                        if context.has_binding(var.name()) {
+                        match &var {
-                            context.set_mutable_binding(var.name(), next_result, true)?;
+                            Declaration::Identifier { ident, .. } => {
-                        } else {
+                                if context.has_binding(ident.as_ref()) {
-                            context.create_mutable_binding(
+                                    context.set_mutable_binding(
-                                var.name().to_owned(),
+                                        ident.as_ref(),
-                                false,
+                                        next_result,
-                                VariableScope::Function,
+                                        true,
-                            )?;
+                                    )?;
-                            context.initialize_binding(var.name(), next_result)?;
+                                } else {
+                                    context.create_mutable_binding(
+                                        ident.to_string(),
+                                        false,
+                                        VariableScope::Function,
+                                    )?;
+                                    context.initialize_binding(ident.as_ref(), next_result)?;
+                                }
+                            }
+                            Declaration::Pattern(p) => {
+                                for (ident, value) in p.run(Some(next_result), context)? {
+                                    if context.has_binding(ident.as_ref()) {
+                                        context.set_mutable_binding(ident.as_ref(), value, true)?;
+                                    } else {
+                                        context.create_mutable_binding(
+                                            ident.to_string(),
+                                            false,
+                                            VariableScope::Function,
+                                        )?;
+                                        context.initialize_binding(ident.as_ref(), value)?;
+                                    }
+                                }
+                            }
                         }
                     }
                     _ => {
@@ -141,13 +163,26 @@ impl Executable for ForOfLoop {
                             return context.throw_syntax_error("a declaration in the head of a for-of loop can't have an initializer");
                         }
 
-                        context.create_mutable_binding(
+                        match &var {
-                            var.name().to_owned(),
+                            Declaration::Identifier { ident, .. } => {
-                            false,
+                                context.create_mutable_binding(
-                            VariableScope::Block,
+                                    ident.to_string(),
-                        )?;
+                                    false,
-
+                                    VariableScope::Block,
-                        context.initialize_binding(var.name(), next_result)?;
+                                )?;
+                                context.initialize_binding(ident.as_ref(), next_result)?;
+                            }
+                            Declaration::Pattern(p) => {
+                                for (ident, value) in p.run(Some(next_result), context)? {
+                                    context.create_mutable_binding(
+                                        ident.to_string(),
+                                        false,
+                                        VariableScope::Block,
+                                    )?;
+                                    context.initialize_binding(ident.as_ref(), value)?;
+                                }
+                            }
+                        }
                     }
                     _ => {
                         return context.throw_syntax_error(
@@ -161,12 +196,26 @@ impl Executable for ForOfLoop {
                             return context.throw_syntax_error("a declaration in the head of a for-of loop can't have an initializer");
                         }
 
-                        context.create_immutable_binding(
+                        match &var {
-                            var.name().to_owned(),
+                            Declaration::Identifier { ident, .. } => {
-                            false,
+                                context.create_immutable_binding(
-                            VariableScope::Block,
+                                    ident.to_string(),
-                        )?;
+                                    false,
-                        context.initialize_binding(var.name(), next_result)?;
+                                    VariableScope::Block,
+                                )?;
+                                context.initialize_binding(ident.as_ref(), next_result)?;
+                            }
+                            Declaration::Pattern(p) => {
+                                for (ident, value) in p.run(Some(next_result), context)? {
+                                    context.create_immutable_binding(
+                                        ident.to_string(),
+                                        false,
+                                        VariableScope::Block,
+                                    )?;
+                                    context.initialize_binding(ident.as_ref(), value)?;
+                                }
+                            }
+                        }
                     }
                     _ => {
                         return context.throw_syntax_error(

boa/src/syntax/ast/node/statement_list/mod.rs

@@ -3,7 +3,7 @@
 use crate::{
     exec::{Executable, InterpreterState},
     gc::{empty_trace, Finalize, Trace},
-    syntax::ast::node::Node,
+    syntax::ast::node::{Declaration, Node},
     BoaProfiler, Context, JsValue, Result,
 };
 use std::{collections::HashSet, fmt, ops::Deref, rc::Rc};
@@ -57,10 +57,21 @@ impl StatementList {
         for stmt in self.items() {
             if let Node::LetDeclList(decl_list) | Node::ConstDeclList(decl_list) = stmt {
                 for decl in decl_list.as_ref() {
-                    if !set.insert(decl.name()) {
+                    // It is a Syntax Error if the LexicallyDeclaredNames of StatementList contains any duplicate entries.
-                        // It is a Syntax Error if the LexicallyDeclaredNames of StatementList contains any duplicate entries.
+                    // https://tc39.es/ecma262/#sec-block-static-semantics-early-errors
-                        // https://tc39.es/ecma262/#sec-block-static-semantics-early-errors
+                    match decl {
-                        unreachable!("Redeclaration of {}", decl.name());
+                        Declaration::Identifier { ident, .. } => {
+                            if !set.insert(ident.as_ref()) {
+                                unreachable!("Redeclaration of {}", ident.as_ref());
+                            }
+                        }
+                        Declaration::Pattern(p) => {
+                            for ident in p.idents() {
+                                if !set.insert(ident) {
+                                    unreachable!("Redeclaration of {}", ident);
+                                }
+                            }
+                        }
                     }
                 }
             }
@@ -83,7 +94,16 @@ impl StatementList {
         for stmt in self.items() {
             if let Node::VarDeclList(decl_list) = stmt {
                 for decl in decl_list.as_ref() {
-                    set.insert(decl.name());
+                    match decl {
+                        Declaration::Identifier { ident, .. } => {
+                            set.insert(ident.as_ref());
+                        }
+                        Declaration::Pattern(p) => {
+                            for ident in p.idents() {
+                                set.insert(ident.as_ref());
+                            }
+                        }
+                    }
                 }
             }
         }

boa/src/syntax/parser/expression/primary/async_function_expression/tests.rs

@@ -15,7 +15,7 @@ fn check_async_expression() {
         };
         ",
         vec![DeclarationList::Const(
-            vec![Declaration::new(
+            vec![Declaration::new_with_identifier(
                 "add",
                 Some(
                     AsyncFunctionExpr::new::<Option<Box<str>>, _, StatementList>(
@@ -43,14 +43,14 @@ fn check_nested_async_expression() {
         };
         ",
         vec![DeclarationList::Const(
-            vec![Declaration::new(
+            vec![Declaration::new_with_identifier(
                 "a",
                 Some(
                     AsyncFunctionExpr::new::<Option<Box<str>>, _, StatementList>(
                         None,
                         [],
                         vec![DeclarationList::Const(
-                            vec![Declaration::new(
+                            vec![Declaration::new_with_identifier(
                                 "b",
                                 Some(
                                     AsyncFunctionExpr::new::<Option<Box<str>>, _, StatementList>(

boa/src/syntax/parser/expression/primary/function_expression/tests.rs

@@ -15,7 +15,7 @@ fn check_function_expression() {
         };
         ",
         vec![DeclarationList::Const(
-            vec![Declaration::new(
+            vec![Declaration::new_with_identifier(
                 "add",
                 Some(
                     FunctionExpr::new::<Option<Box<str>>, _, StatementList>(
@@ -43,14 +43,14 @@ fn check_nested_function_expression() {
         };
         ",
         vec![DeclarationList::Const(
-            vec![Declaration::new(
+            vec![Declaration::new_with_identifier(
                 "a",
                 Some(
                     FunctionExpr::new::<Option<Box<str>>, _, StatementList>(
                         None,
                         [],
                         vec![DeclarationList::Const(
-                            vec![Declaration::new(
+                            vec![Declaration::new_with_identifier(
                                 "b",
                                 Some(
                                     FunctionExpr::new::<Option<Box<str>>, _, StatementList>(

boa/src/syntax/parser/expression/primary/object_initializer/tests.rs

@@ -24,7 +24,7 @@ fn check_object_literal() {
         };
         ",
         vec![DeclarationList::Const(
-            vec![Declaration::new(
+            vec![Declaration::new_with_identifier(
                 "x",
                 Some(Object::from(object_properties).into()),
             )]
@@ -53,7 +53,7 @@ fn check_object_short_function() {
         };
         ",
         vec![DeclarationList::Const(
-            vec![Declaration::new(
+            vec![Declaration::new_with_identifier(
                 "x",
                 Some(Object::from(object_properties).into()),
             )]
@@ -86,7 +86,7 @@ fn check_object_short_function_arguments() {
          };
         ",
         vec![DeclarationList::Const(
-            vec![Declaration::new(
+            vec![Declaration::new_with_identifier(
                 "x",
                 Some(Object::from(object_properties).into()),
             )]
@@ -114,7 +114,7 @@ fn check_object_getter() {
         };
         ",
         vec![DeclarationList::Const(
-            vec![Declaration::new(
+            vec![Declaration::new_with_identifier(
                 "x",
                 Some(Object::from(object_properties).into()),
             )]
@@ -146,7 +146,7 @@ fn check_object_setter() {
         };
         ",
         vec![DeclarationList::Const(
-            vec![Declaration::new(
+            vec![Declaration::new_with_identifier(
                 "x",
                 Some(Object::from(object_properties).into()),
             )]
@@ -170,7 +170,7 @@ fn check_object_short_function_get() {
          };
         ",
         vec![DeclarationList::Const(
-            vec![Declaration::new(
+            vec![Declaration::new_with_identifier(
                 "x",
                 Some(Object::from(object_properties).into()),
             )]
@@ -194,7 +194,7 @@ fn check_object_short_function_set() {
          };
         ",
         vec![DeclarationList::Const(
-            vec![Declaration::new(
+            vec![Declaration::new_with_identifier(
                 "x",
                 Some(Object::from(object_properties).into()),
             )]

boa/src/syntax/parser/function/tests.rs

@@ -193,7 +193,7 @@ fn check_arrow_assignment() {
     check_parser(
         "let foo = (a) => { return a };",
         vec![DeclarationList::Let(
-            vec![Declaration::new(
+            vec![Declaration::new_with_identifier(
                 Identifier::from("foo"),
                 Some(
                     ArrowFunctionDecl::new(
@@ -218,7 +218,7 @@ fn check_arrow_assignment_nobrackets() {
     check_parser(
         "let foo = (a) => a;",
         vec![DeclarationList::Let(
-            vec![Declaration::new(
+            vec![Declaration::new_with_identifier(
                 Identifier::from("foo"),
                 Some(
                     ArrowFunctionDecl::new(
@@ -243,7 +243,7 @@ fn check_arrow_assignment_noparenthesis() {
     check_parser(
         "let foo = a => { return a };",
         vec![DeclarationList::Let(
-            vec![Declaration::new(
+            vec![Declaration::new_with_identifier(
                 Identifier::from("foo"),
                 Some(
                     ArrowFunctionDecl::new(
@@ -268,7 +268,7 @@ fn check_arrow_assignment_noparenthesis_nobrackets() {
     check_parser(
         "let foo = a => a;",
         vec![DeclarationList::Let(
-            vec![Declaration::new(
+            vec![Declaration::new_with_identifier(
                 Identifier::from("foo"),
                 Some(
                     ArrowFunctionDecl::new(
@@ -293,7 +293,7 @@ fn check_arrow_assignment_2arg() {
     check_parser(
         "let foo = (a, b) => { return a };",
         vec![DeclarationList::Let(
-            vec![Declaration::new(
+            vec![Declaration::new_with_identifier(
                 Identifier::from("foo"),
                 Some(
                     ArrowFunctionDecl::new(
@@ -321,7 +321,7 @@ fn check_arrow_assignment_2arg_nobrackets() {
     check_parser(
         "let foo = (a, b) => a;",
         vec![DeclarationList::Let(
-            vec![Declaration::new(
+            vec![Declaration::new_with_identifier(
                 Identifier::from("foo"),
                 Some(
                     ArrowFunctionDecl::new(
@@ -349,7 +349,7 @@ fn check_arrow_assignment_3arg() {
     check_parser(
         "let foo = (a, b, c) => { return a };",
         vec![DeclarationList::Let(
-            vec![Declaration::new(
+            vec![Declaration::new_with_identifier(
                 Identifier::from("foo"),
                 Some(
                     ArrowFunctionDecl::new(
@@ -378,7 +378,7 @@ fn check_arrow_assignment_3arg_nobrackets() {
     check_parser(
         "let foo = (a, b, c) => a;",
         vec![DeclarationList::Let(
-            vec![Declaration::new(
+            vec![Declaration::new_with_identifier(
                 Identifier::from("foo"),
                 Some(
                     ArrowFunctionDecl::new(

boa/src/syntax/parser/statement/block/tests.rs

@@ -33,8 +33,14 @@ fn non_empty() {
             a++;
         }",
         vec![
-            DeclarationList::Var(vec![Declaration::new("a", Some(Const::from(10).into()))].into())
+            DeclarationList::Var(
+                vec![Declaration::new_with_identifier(
+                    "a",
+                    Some(Const::from(10).into()),
+                )]
                 .into(),
+            )
+            .into(),
             UnaryOp::new(op::UnaryOp::IncrementPost, Identifier::from("a")).into(),
         ],
     );
@@ -56,7 +62,7 @@ fn non_empty() {
             )
             .into(),
             DeclarationList::Var(
-                vec![Declaration::new(
+                vec![Declaration::new_with_identifier(
                     "a",
                     Node::from(Call::new(Identifier::from("hello"), vec![])),
                 )]
@@ -85,7 +91,7 @@ fn hoisting() {
             )
             .into(),
             DeclarationList::Var(
-                vec![Declaration::new(
+                vec![Declaration::new_with_identifier(
                     "a",
                     Node::from(Call::new(Identifier::from("hello"), vec![])),
                 )]
@@ -106,7 +112,7 @@ fn hoisting() {
         vec![
             Assign::new(Identifier::from("a"), Const::from(10)).into(),
             UnaryOp::new(op::UnaryOp::IncrementPost, Identifier::from("a")).into(),
-            DeclarationList::Var(vec![Declaration::new("a", None)].into()).into(),
+            DeclarationList::Var(vec![Declaration::new_with_identifier("a", None)].into()).into(),
         ],
     );
 }

boa/src/syntax/parser/statement/declaration/lexical.rs

@@ -7,7 +7,6 @@
 //!
 //! [spec]: https://tc39.es/ecma262/#sec-let-and-const-declarations
 
-use crate::syntax::lexer::TokenKind;
 use crate::{
     syntax::{
         ast::{
@@ -17,10 +16,11 @@ use crate::{
             },
             Keyword, Punctuator,
         },
+        lexer::TokenKind,
         parser::{
             cursor::{Cursor, SemicolonResult},
             expression::Initializer,
-            statement::BindingIdentifier,
+            statement::{ArrayBindingPattern, BindingIdentifier, ObjectBindingPattern},
             AllowAwait, AllowIn, AllowYield, ParseError, ParseResult, TokenParser,
         },
     },
@@ -154,14 +154,19 @@ where
         let mut const_decls = Vec::new();
 
         loop {
-            let (ident, init) =
+            let decl = LexicalBinding::new(self.allow_in, self.allow_yield, self.allow_await)
-                LexicalBinding::new(self.allow_in, self.allow_yield, self.allow_await)
+                .parse(cursor)?;
-                    .parse(cursor)?;
 
             if self.is_const {
                 if self.const_init_required {
-                    if init.is_some() {
+                    let init_is_some = match &decl {
-                        const_decls.push(Declaration::new(ident, init));
+                        Declaration::Identifier { init, .. } if init.is_some() => true,
+                        Declaration::Pattern(p) if p.init().is_some() => true,
+                        _ => false,
+                    };
+
+                    if init_is_some {
+                        const_decls.push(decl);
                     } else {
                         return Err(ParseError::expected(
                             vec![TokenKind::Punctuator(Punctuator::Assign)],
@@ -170,10 +175,10 @@ where
                         ));
                     }
                 } else {
-                    const_decls.push(Declaration::new(ident, init))
+                    const_decls.push(decl)
                 }
             } else {
-                let_decls.push(Declaration::new(ident, init));
+                let_decls.push(decl);
             }
 
             match cursor.peek_semicolon()? {
@@ -243,26 +248,74 @@ impl<R> TokenParser<R> for LexicalBinding
 where
     R: Read,
 {
-    type Output = (Box<str>, Option<Node>);
+    type Output = Declaration;
 
     fn parse(self, cursor: &mut Cursor<R>) -> Result<Self::Output, ParseError> {
         let _timer = BoaProfiler::global().start_event("LexicalBinding", "Parsing");
 
-        let ident = BindingIdentifier::new(self.allow_yield, self.allow_await).parse(cursor)?;
+        let peek_token = cursor.peek(0)?.ok_or(ParseError::AbruptEnd)?;
 
-        let init = if let Some(t) = cursor.peek(0)? {
+        match peek_token.kind() {
-            if *t.kind() == TokenKind::Punctuator(Punctuator::Assign) {
+            TokenKind::Punctuator(Punctuator::OpenBlock) => {
-                Some(
+                let bindings =
-                    Initializer::new(self.allow_in, self.allow_yield, self.allow_await)
+                    ObjectBindingPattern::new(self.allow_in, self.allow_yield, self.allow_await)
-                        .parse(cursor)?,
+                        .parse(cursor)?;
-                )
+
-            } else {
+                let init = if let Some(t) = cursor.peek(0)? {
-                None
+                    if *t.kind() == TokenKind::Punctuator(Punctuator::Assign) {
+                        Some(
+                            Initializer::new(self.allow_in, self.allow_yield, self.allow_await)
+                                .parse(cursor)?,
+                        )
+                    } else {
+                        None
+                    }
+                } else {
+                    None
+                };
+
+                Ok(Declaration::new_with_object_pattern(bindings, init))
             }
-        } else {
+            TokenKind::Punctuator(Punctuator::OpenBracket) => {
-            None
+                let bindings =
-        };
+                    ArrayBindingPattern::new(self.allow_in, self.allow_yield, self.allow_await)
+                        .parse(cursor)?;
 
-        Ok((ident, init))
+                let init = if let Some(t) = cursor.peek(0)? {
+                    if *t.kind() == TokenKind::Punctuator(Punctuator::Assign) {
+                        Some(
+                            Initializer::new(self.allow_in, self.allow_yield, self.allow_await)
+                                .parse(cursor)?,
+                        )
+                    } else {
+                        None
+                    }
+                } else {
+                    None
+                };
+
+                Ok(Declaration::new_with_array_pattern(bindings, init))
+            }
+
+            _ => {
+                let ident =
+                    BindingIdentifier::new(self.allow_yield, self.allow_await).parse(cursor)?;
+
+                let init = if let Some(t) = cursor.peek(0)? {
+                    if *t.kind() == TokenKind::Punctuator(Punctuator::Assign) {
+                        Some(
+                            Initializer::new(true, self.allow_yield, self.allow_await)
+                                .parse(cursor)?,
+                        )
+                    } else {
+                        None
+                    }
+                } else {
+                    None
+                };
+
+                Ok(Declaration::new_with_identifier(ident, init))
+            }
+        }
     }
 }

boa/src/syntax/parser/statement/declaration/tests.rs

@@ -11,10 +11,14 @@ use crate::syntax::{
 fn var_declaration() {
     check_parser(
         "var a = 5;",
-        vec![
+        vec![DeclarationList::Var(
-            DeclarationList::Var(vec![Declaration::new("a", Some(Const::from(5).into()))].into())
+            vec![Declaration::new_with_identifier(
-                .into(),
+                "a",
-        ],
+                Some(Const::from(5).into()),
+            )]
+            .into(),
+        )
+        .into()],
     );
 }
 
@@ -24,7 +28,11 @@ fn var_declaration_keywords() {
     check_parser(
         "var yield = 5;",
         vec![DeclarationList::Var(
-            vec![Declaration::new("yield", Some(Const::from(5).into()))].into(),
+            vec![Declaration::new_with_identifier(
+                "yield",
+                Some(Const::from(5).into()),
+            )]
+            .into(),
         )
         .into()],
     );
@@ -32,7 +40,11 @@ fn var_declaration_keywords() {
     check_parser(
         "var await = 5;",
         vec![DeclarationList::Var(
-            vec![Declaration::new("await", Some(Const::from(5).into()))].into(),
+            vec![Declaration::new_with_identifier(
+                "await",
+                Some(Const::from(5).into()),
+            )]
+            .into(),
         )
         .into()],
     );
@@ -43,10 +55,14 @@ fn var_declaration_keywords() {
 fn var_declaration_no_spaces() {
     check_parser(
         "var a=5;",
-        vec![
+        vec![DeclarationList::Var(
-            DeclarationList::Var(vec![Declaration::new("a", Some(Const::from(5).into()))].into())
+            vec![Declaration::new_with_identifier(
-                .into(),
+                "a",
-        ],
+                Some(Const::from(5).into()),
+            )]
+            .into(),
+        )
+        .into()],
     );
 }
 
@@ -55,7 +71,7 @@ fn var_declaration_no_spaces() {
 fn empty_var_declaration() {
     check_parser(
         "var a;",
-        vec![DeclarationList::Var(vec![Declaration::new("a", None)].into()).into()],
+        vec![DeclarationList::Var(vec![Declaration::new_with_identifier("a", None)].into()).into()],
     );
 }
 
@@ -66,9 +82,9 @@ fn multiple_var_declaration() {
         "var a = 5, b, c = 6;",
         vec![DeclarationList::Var(
             vec![
-                Declaration::new("a", Some(Const::from(5).into())),
+                Declaration::new_with_identifier("a", Some(Const::from(5).into())),
-                Declaration::new("b", None),
+                Declaration::new_with_identifier("b", None),
-                Declaration::new("c", Some(Const::from(6).into())),
+                Declaration::new_with_identifier("c", Some(Const::from(6).into())),
             ]
             .into(),
         )
@@ -81,10 +97,14 @@ fn multiple_var_declaration() {
 fn let_declaration() {
     check_parser(
         "let a = 5;",
-        vec![
+        vec![DeclarationList::Let(
-            DeclarationList::Let(vec![Declaration::new("a", Node::from(Const::from(5)))].into())
+            vec![Declaration::new_with_identifier(
-                .into(),
+                "a",
-        ],
+                Node::from(Const::from(5)),
+            )]
+            .into(),
+        )
+        .into()],
     );
 }
 
@@ -94,7 +114,11 @@ fn let_declaration_keywords() {
     check_parser(
         "let yield = 5;",
         vec![DeclarationList::Let(
-            vec![Declaration::new("yield", Node::from(Const::from(5)))].into(),
+            vec![Declaration::new_with_identifier(
+                "yield",
+                Node::from(Const::from(5)),
+            )]
+            .into(),
         )
         .into()],
     );
@@ -102,7 +126,11 @@ fn let_declaration_keywords() {
     check_parser(
         "let await = 5;",
         vec![DeclarationList::Let(
-            vec![Declaration::new("await", Node::from(Const::from(5)))].into(),
+            vec![Declaration::new_with_identifier(
+                "await",
+                Node::from(Const::from(5)),
+            )]
+            .into(),
         )
         .into()],
     );
@@ -113,10 +141,14 @@ fn let_declaration_keywords() {
 fn let_declaration_no_spaces() {
     check_parser(
         "let a=5;",
-        vec![
+        vec![DeclarationList::Let(
-            DeclarationList::Let(vec![Declaration::new("a", Node::from(Const::from(5)))].into())
+            vec![Declaration::new_with_identifier(
-                .into(),
+                "a",
-        ],
+                Node::from(Const::from(5)),
+            )]
+            .into(),
+        )
+        .into()],
     );
 }
 
@@ -125,7 +157,7 @@ fn let_declaration_no_spaces() {
 fn empty_let_declaration() {
     check_parser(
         "let a;",
-        vec![DeclarationList::Let(vec![Declaration::new("a", None)].into()).into()],
+        vec![DeclarationList::Let(vec![Declaration::new_with_identifier("a", None)].into()).into()],
     );
 }
 
@@ -136,9 +168,9 @@ fn multiple_let_declaration() {
         "let a = 5, b, c = 6;",
         vec![DeclarationList::Let(
             vec![
-                Declaration::new("a", Node::from(Const::from(5))),
+                Declaration::new_with_identifier("a", Node::from(Const::from(5))),
-                Declaration::new("b", None),
+                Declaration::new_with_identifier("b", None),
-                Declaration::new("c", Node::from(Const::from(6))),
+                Declaration::new_with_identifier("c", Node::from(Const::from(6))),
             ]
             .into(),
         )
@@ -152,7 +184,11 @@ fn const_declaration() {
     check_parser(
         "const a = 5;",
         vec![DeclarationList::Const(
-            vec![Declaration::new("a", Node::from(Const::from(5)))].into(),
+            vec![Declaration::new_with_identifier(
+                "a",
+                Node::from(Const::from(5)),
+            )]
+            .into(),
         )
         .into()],
     );
@@ -164,7 +200,11 @@ fn const_declaration_keywords() {
     check_parser(
         "const yield = 5;",
         vec![DeclarationList::Const(
-            vec![Declaration::new("yield", Node::from(Const::from(5)))].into(),
+            vec![Declaration::new_with_identifier(
+                "yield",
+                Node::from(Const::from(5)),
+            )]
+            .into(),
         )
         .into()],
     );
@@ -172,7 +212,11 @@ fn const_declaration_keywords() {
     check_parser(
         "const await = 5;",
         vec![DeclarationList::Const(
-            vec![Declaration::new("await", Node::from(Const::from(5)))].into(),
+            vec![Declaration::new_with_identifier(
+                "await",
+                Node::from(Const::from(5)),
+            )]
+            .into(),
         )
         .into()],
     );
@@ -184,7 +228,11 @@ fn const_declaration_no_spaces() {
     check_parser(
         "const a=5;",
         vec![DeclarationList::Const(
-            vec![Declaration::new("a", Node::from(Const::from(5)))].into(),
+            vec![Declaration::new_with_identifier(
+                "a",
+                Node::from(Const::from(5)),
+            )]
+            .into(),
         )
         .into()],
     );
@@ -203,8 +251,8 @@ fn multiple_const_declaration() {
         "const a = 5, c = 6;",
         vec![DeclarationList::Const(
             vec![
-                Declaration::new("a", Node::from(Const::from(5))),
+                Declaration::new_with_identifier("a", Node::from(Const::from(5))),
-                Declaration::new("c", Node::from(Const::from(6))),
+                Declaration::new_with_identifier("c", Node::from(Const::from(6))),
             ]
             .into(),
         )

boa/src/syntax/parser/statement/iteration/tests.rs

@@ -37,8 +37,14 @@ fn check_do_while_semicolon_insertion() {
         r#"var i = 0;
         do {console.log("hello");} while(i++ < 10) console.log("end");"#,
         vec![
-            DeclarationList::Var(vec![Declaration::new("i", Some(Const::from(0).into()))].into())
+            DeclarationList::Var(
+                vec![Declaration::new_with_identifier(
+                    "i",
+                    Some(Const::from(0).into()),
+                )]
                 .into(),
+            )
+            .into(),
             DoWhileLoop::new(
                 Block::from(vec![Call::new(
                     GetConstField::new(Identifier::from("console"), "log"),
@@ -69,8 +75,14 @@ fn check_do_while_semicolon_insertion_no_space() {
         r#"var i = 0;
         do {console.log("hello");} while(i++ < 10)console.log("end");"#,
         vec![
-            DeclarationList::Var(vec![Declaration::new("i", Some(Const::from(0).into()))].into())
+            DeclarationList::Var(
+                vec![Declaration::new_with_identifier(
+                    "i",
+                    Some(Const::from(0).into()),
+                )]
                 .into(),
+            )
+            .into(),
             DoWhileLoop::new(
                 Block::from(vec![Call::new(
                     GetConstField::new(Identifier::from("console"), "log"),

boa/src/syntax/parser/statement/mod.rs

@@ -35,12 +35,24 @@ use self::{
     try_stm::TryStatement,
     variable::VariableStatement,
 };
+use crate::syntax::{
+    ast::node::declaration::{
+        DeclarationPattern, DeclarationPatternArray, DeclarationPatternObject,
+    },
+    parser::expression::Initializer,
+};
 
-use super::{AllowAwait, AllowReturn, AllowYield, Cursor, ParseError, TokenParser};
+use super::{AllowAwait, AllowIn, AllowReturn, AllowYield, Cursor, ParseError, TokenParser};
 
 use crate::{
     syntax::{
-        ast::{node, Keyword, Node, Punctuator},
+        ast::{
+            node::{
+                self,
+                declaration::{BindingPatternTypeArray, BindingPatternTypeObject},
+            },
+            Keyword, Node, Punctuator,
+        },
         lexer::{Error as LexError, InputElement, Position, TokenKind},
         parser::expression::await_expr::AwaitExpression,
     },
@@ -48,8 +60,8 @@ use crate::{
 };
 use labelled_stm::LabelledStatement;
 
-use std::collections::HashSet;
 use std::io::Read;
+use std::{collections::HashSet, vec};
 
 /// Statement parsing.
 ///
@@ -303,33 +315,82 @@ where
                         for decl in decl_list.as_ref() {
                             // if name in VarDeclaredNames or can't be added to
                             // LexicallyDeclaredNames, raise an error
-                            if var_declared_names.contains(decl.name())
+                            match decl {
-                                || !lexically_declared_names.insert(decl.name())
+                                node::Declaration::Identifier { ident, .. } => {
-                            {
+                                    if var_declared_names.contains(ident.as_ref())
-                                return Err(ParseError::lex(LexError::Syntax(
+                                        || !lexically_declared_names.insert(ident.as_ref())
-                                    format!("Redeclaration of variable `{}`", decl.name()).into(),
+                                    {
-                                    match cursor.peek(0)? {
+                                        return Err(ParseError::lex(LexError::Syntax(
-                                        Some(token) => token.span().end(),
+                                            format!(
-                                        None => Position::new(1, 1),
+                                                "Redeclaration of variable `{}`",
-                                    },
+                                                ident.as_ref()
-                                )));
+                                            )
+                                            .into(),
+                                            match cursor.peek(0)? {
+                                                Some(token) => token.span().end(),
+                                                None => Position::new(1, 1),
+                                            },
+                                        )));
+                                    }
+                                }
+                                node::Declaration::Pattern(p) => {
+                                    for ident in p.idents() {
+                                        if var_declared_names.contains(ident)
+                                            || !lexically_declared_names.insert(ident.as_ref())
+                                        {
+                                            return Err(ParseError::lex(LexError::Syntax(
+                                                format!("Redeclaration of variable `{}`", ident)
+                                                    .into(),
+                                                match cursor.peek(0)? {
+                                                    Some(token) => token.span().end(),
+                                                    None => Position::new(1, 1),
+                                                },
+                                            )));
+                                        }
+                                    }
+                                }
                             }
                         }
                     }
                     Node::VarDeclList(decl_list) => {
                         for decl in decl_list.as_ref() {
-                            // if name in LexicallyDeclaredNames, raise an error
+                            match decl {
-                            if lexically_declared_names.contains(decl.name()) {
+                                node::Declaration::Identifier { ident, .. } => {
-                                return Err(ParseError::lex(LexError::Syntax(
+                                    // if name in LexicallyDeclaredNames, raise an error
-                                    format!("Redeclaration of variable `{}`", decl.name()).into(),
+                                    if lexically_declared_names.contains(ident.as_ref()) {
-                                    match cursor.peek(0)? {
+                                        return Err(ParseError::lex(LexError::Syntax(
-                                        Some(token) => token.span().end(),
+                                            format!(
-                                        None => Position::new(1, 1),
+                                                "Redeclaration of variable `{}`",
-                                    },
+                                                ident.as_ref()
-                                )));
+                                            )
+                                            .into(),
+                                            match cursor.peek(0)? {
+                                                Some(token) => token.span().end(),
+                                                None => Position::new(1, 1),
+                                            },
+                                        )));
+                                    }
+                                    // otherwise, add to VarDeclaredNames
+                                    var_declared_names.insert(ident.as_ref());
+                                }
+                                node::Declaration::Pattern(p) => {
+                                    for ident in p.idents() {
+                                        // if name in LexicallyDeclaredNames, raise an error
+                                        if lexically_declared_names.contains(ident) {
+                                            return Err(ParseError::lex(LexError::Syntax(
+                                                format!("Redeclaration of variable `{}`", ident)
+                                                    .into(),
+                                                match cursor.peek(0)? {
+                                                    Some(token) => token.span().end(),
+                                                    None => Position::new(1, 1),
+                                                },
+                                            )));
+                                        }
+                                        // otherwise, add to VarDeclaredNames
+                                        var_declared_names.insert(ident.as_ref());
+                                    }
+                                }
                             }
-                            // otherwise, add to VarDeclaredNames
-                            var_declared_names.insert(decl.name());
                         }
                     }
                     _ => (),
@@ -487,3 +548,487 @@ where
         }
     }
 }
+
+/// ObjectBindingPattern pattern parsing.
+///
+/// More information:
+///  - [ECMAScript specification][spec]
+///
+/// [spec]: https://tc39.es/ecma262/#prod-ObjectBindingPattern
+#[derive(Debug, Clone, Copy)]
+pub(super) struct ObjectBindingPattern {
+    allow_in: AllowIn,
+    allow_yield: AllowYield,
+    allow_await: AllowAwait,
+}
+
+impl ObjectBindingPattern {
+    /// Creates a new `ObjectBindingPattern` parser.
+    pub(super) fn new<I, Y, A>(allow_in: I, allow_yield: Y, allow_await: A) -> Self
+    where
+        I: Into<AllowIn>,
+        Y: Into<AllowYield>,
+        A: Into<AllowAwait>,
+    {
+        Self {
+            allow_in: allow_in.into(),
+            allow_yield: allow_yield.into(),
+            allow_await: allow_await.into(),
+        }
+    }
+}
+
+impl<R> TokenParser<R> for ObjectBindingPattern
+where
+    R: Read,
+{
+    type Output = Vec<BindingPatternTypeObject>;
+
+    fn parse(self, cursor: &mut Cursor<R>) -> Result<Self::Output, ParseError> {
+        let _timer = BoaProfiler::global().start_event("ObjectBindingPattern", "Parsing");
+
+        cursor.expect(
+            TokenKind::Punctuator(Punctuator::OpenBlock),
+            "object binding pattern",
+        )?;
+
+        let mut patterns = Vec::new();
+        let mut property_names = Vec::new();
+        let mut rest_property_name = None;
+
+        loop {
+            let property_name = match cursor.peek(0)?.ok_or(ParseError::AbruptEnd)?.kind() {
+                TokenKind::Punctuator(Punctuator::CloseBlock) => {
+                    cursor.expect(
+                        TokenKind::Punctuator(Punctuator::CloseBlock),
+                        "object binding pattern",
+                    )?;
+                    break;
+                }
+                TokenKind::Punctuator(Punctuator::Spread) => {
+                    cursor.expect(
+                        TokenKind::Punctuator(Punctuator::Spread),
+                        "object binding pattern",
+                    )?;
+                    rest_property_name = Some(
+                        BindingIdentifier::new(self.allow_yield, self.allow_await).parse(cursor)?,
+                    );
+                    cursor.expect(
+                        TokenKind::Punctuator(Punctuator::CloseBlock),
+                        "object binding pattern",
+                    )?;
+                    break;
+                }
+                _ => BindingIdentifier::new(self.allow_yield, self.allow_await).parse(cursor)?,
+            };
+
+            property_names.push(property_name.clone());
+
+            if let Some(peek_token) = cursor.peek(0)? {
+                match peek_token.kind() {
+                    TokenKind::Punctuator(Punctuator::Assign) => {
+                        let init =
+                            Initializer::new(self.allow_in, self.allow_yield, self.allow_await)
+                                .parse(cursor)?;
+                        patterns.push(BindingPatternTypeObject::SingleName {
+                            ident: property_name.clone(),
+                            property_name,
+                            default_init: Some(init),
+                        });
+                    }
+                    TokenKind::Punctuator(Punctuator::Colon) => {
+                        cursor.expect(
+                            TokenKind::Punctuator(Punctuator::Colon),
+                            "object binding pattern",
+                        )?;
+
+                        if let Some(peek_token) = cursor.peek(0)? {
+                            match peek_token.kind() {
+                                TokenKind::Punctuator(Punctuator::OpenBlock) => {
+                                    let bindings = ObjectBindingPattern::new(
+                                        self.allow_in,
+                                        self.allow_yield,
+                                        self.allow_await,
+                                    )
+                                    .parse(cursor)?;
+
+                                    if let Some(peek_token) = cursor.peek(0)? {
+                                        match peek_token.kind() {
+                                            TokenKind::Punctuator(Punctuator::Assign) => {
+                                                let init = Initializer::new(
+                                                    self.allow_in,
+                                                    self.allow_yield,
+                                                    self.allow_await,
+                                                )
+                                                .parse(cursor)?;
+                                                patterns.push(
+                                                    BindingPatternTypeObject::BindingPattern {
+                                                        ident: property_name,
+                                                        pattern: DeclarationPattern::Object(
+                                                            DeclarationPatternObject::new(
+                                                                bindings, None,
+                                                            ),
+                                                        ),
+                                                        default_init: Some(init),
+                                                    },
+                                                );
+                                            }
+                                            _ => {
+                                                patterns.push(
+                                                    BindingPatternTypeObject::BindingPattern {
+                                                        ident: property_name,
+                                                        pattern: DeclarationPattern::Object(
+                                                            DeclarationPatternObject::new(
+                                                                bindings, None,
+                                                            ),
+                                                        ),
+                                                        default_init: None,
+                                                    },
+                                                );
+                                            }
+                                        }
+                                    }
+                                }
+                                TokenKind::Punctuator(Punctuator::OpenBracket) => {
+                                    let bindings = ArrayBindingPattern::new(
+                                        self.allow_in,
+                                        self.allow_yield,
+                                        self.allow_await,
+                                    )
+                                    .parse(cursor)?;
+
+                                    if let Some(peek_token) = cursor.peek(0)? {
+                                        match peek_token.kind() {
+                                            TokenKind::Punctuator(Punctuator::Assign) => {
+                                                let init = Initializer::new(
+                                                    self.allow_in,
+                                                    self.allow_yield,
+                                                    self.allow_await,
+                                                )
+                                                .parse(cursor)?;
+                                                patterns.push(
+                                                    BindingPatternTypeObject::BindingPattern {
+                                                        ident: property_name,
+                                                        pattern: DeclarationPattern::Array(
+                                                            DeclarationPatternArray::new(
+                                                                bindings, None,
+                                                            ),
+                                                        ),
+                                                        default_init: Some(init),
+                                                    },
+                                                );
+                                            }
+                                            _ => {
+                                                patterns.push(
+                                                    BindingPatternTypeObject::BindingPattern {
+                                                        ident: property_name,
+                                                        pattern: DeclarationPattern::Array(
+                                                            DeclarationPatternArray::new(
+                                                                bindings, None,
+                                                            ),
+                                                        ),
+                                                        default_init: None,
+                                                    },
+                                                );
+                                            }
+                                        }
+                                    }
+                                }
+                                _ => {
+                                    // TODO: Currently parses only BindingIdentifier.
+                                    //       Should parse https://tc39.es/ecma262/#prod-PropertyName
+                                    let ident =
+                                        BindingIdentifier::new(self.allow_yield, self.allow_await)
+                                            .parse(cursor)?;
+
+                                    if let Some(peek_token) = cursor.peek(0)? {
+                                        match peek_token.kind() {
+                                            TokenKind::Punctuator(Punctuator::Assign) => {
+                                                let init = Initializer::new(
+                                                    self.allow_in,
+                                                    self.allow_yield,
+                                                    self.allow_await,
+                                                )
+                                                .parse(cursor)?;
+                                                patterns.push(
+                                                    BindingPatternTypeObject::SingleName {
+                                                        ident,
+                                                        property_name,
+                                                        default_init: Some(init),
+                                                    },
+                                                );
+                                            }
+                                            _ => {
+                                                patterns.push(
+                                                    BindingPatternTypeObject::SingleName {
+                                                        ident,
+                                                        property_name,
+                                                        default_init: None,
+                                                    },
+                                                );
+                                            }
+                                        }
+                                    }
+                                }
+                            }
+                        }
+                    }
+                    _ => {
+                        patterns.push(BindingPatternTypeObject::SingleName {
+                            ident: property_name.clone(),
+                            property_name,
+                            default_init: None,
+                        });
+                    }
+                }
+            }
+
+            if let Some(peek_token) = cursor.peek(0)? {
+                if let TokenKind::Punctuator(Punctuator::Comma) = peek_token.kind() {
+                    cursor.expect(
+                        TokenKind::Punctuator(Punctuator::Comma),
+                        "object binding pattern",
+                    )?;
+                }
+            }
+        }
+
+        if let Some(rest) = rest_property_name {
+            if patterns.is_empty() {
+                Ok(vec![BindingPatternTypeObject::RestProperty {
+                    ident: rest,
+                    excluded_keys: property_names,
+                }])
+            } else {
+                patterns.push(BindingPatternTypeObject::RestProperty {
+                    ident: rest,
+                    excluded_keys: property_names,
+                });
+                Ok(patterns)
+            }
+        } else if patterns.is_empty() {
+            Ok(vec![BindingPatternTypeObject::Empty])
+        } else {
+            Ok(patterns)
+        }
+    }
+}
+
+/// ArrayBindingPattern pattern parsing.
+///
+/// More information:
+///  - [ECMAScript specification][spec]
+///
+/// [spec]: https://tc39.es/ecma262/#prod-ArrayBindingPattern
+#[derive(Debug, Clone, Copy)]
+pub(super) struct ArrayBindingPattern {
+    allow_in: AllowIn,
+    allow_yield: AllowYield,
+    allow_await: AllowAwait,
+}
+
+impl ArrayBindingPattern {
+    /// Creates a new `ArrayBindingPattern` parser.
+    pub(super) fn new<I, Y, A>(allow_in: I, allow_yield: Y, allow_await: A) -> Self
+    where
+        I: Into<AllowIn>,
+        Y: Into<AllowYield>,
+        A: Into<AllowAwait>,
+    {
+        Self {
+            allow_in: allow_in.into(),
+            allow_yield: allow_yield.into(),
+            allow_await: allow_await.into(),
+        }
+    }
+}
+
+impl<R> TokenParser<R> for ArrayBindingPattern
+where
+    R: Read,
+{
+    type Output = Vec<BindingPatternTypeArray>;
+
+    fn parse(self, cursor: &mut Cursor<R>) -> Result<Self::Output, ParseError> {
+        let _timer = BoaProfiler::global().start_event("ArrayBindingPattern", "Parsing");
+
+        cursor.expect(
+            TokenKind::Punctuator(Punctuator::OpenBracket),
+            "array binding pattern",
+        )?;
+
+        let mut patterns = Vec::new();
+        let mut last_elision_or_first = true;
+
+        loop {
+            match cursor.peek(0)?.ok_or(ParseError::AbruptEnd)?.kind() {
+                TokenKind::Punctuator(Punctuator::CloseBracket) => {
+                    cursor.expect(
+                        TokenKind::Punctuator(Punctuator::CloseBracket),
+                        "array binding pattern",
+                    )?;
+                    break;
+                }
+                TokenKind::Punctuator(Punctuator::Comma) => {
+                    cursor.expect(
+                        TokenKind::Punctuator(Punctuator::Comma),
+                        "array binding pattern",
+                    )?;
+                    if last_elision_or_first {
+                        patterns.push(BindingPatternTypeArray::Elision);
+                    } else {
+                        last_elision_or_first = true;
+                    }
+                    continue;
+                }
+                TokenKind::Punctuator(Punctuator::Spread) => {
+                    cursor.expect(
+                        TokenKind::Punctuator(Punctuator::Spread),
+                        "array binding pattern",
+                    )?;
+
+                    match cursor.peek(0)?.ok_or(ParseError::AbruptEnd)?.kind() {
+                        TokenKind::Punctuator(Punctuator::OpenBlock) => {
+                            let bindings = ObjectBindingPattern::new(
+                                self.allow_in,
+                                self.allow_yield,
+                                self.allow_await,
+                            )
+                            .parse(cursor)?;
+                            patterns.push(BindingPatternTypeArray::BindingPatternRest {
+                                pattern: DeclarationPattern::Object(DeclarationPatternObject::new(
+                                    bindings, None,
+                                )),
+                            });
+                        }
+                        TokenKind::Punctuator(Punctuator::OpenBracket) => {
+                            let bindings = ArrayBindingPattern::new(
+                                self.allow_in,
+                                self.allow_yield,
+                                self.allow_await,
+                            )
+                            .parse(cursor)?;
+                            patterns.push(BindingPatternTypeArray::BindingPatternRest {
+                                pattern: DeclarationPattern::Array(DeclarationPatternArray::new(
+                                    bindings, None,
+                                )),
+                            });
+                        }
+                        _ => {
+                            let rest_property_name =
+                                BindingIdentifier::new(self.allow_yield, self.allow_await)
+                                    .parse(cursor)?;
+                            patterns.push(BindingPatternTypeArray::SingleNameRest {
+                                ident: rest_property_name,
+                            });
+                        }
+                    }
+
+                    cursor.expect(
+                        TokenKind::Punctuator(Punctuator::CloseBracket),
+                        "array binding pattern",
+                    )?;
+                    break;
+                }
+                TokenKind::Punctuator(Punctuator::OpenBlock) => {
+                    last_elision_or_first = false;
+
+                    let bindings = ObjectBindingPattern::new(
+                        self.allow_in,
+                        self.allow_yield,
+                        self.allow_await,
+                    )
+                    .parse(cursor)?;
+
+                    match cursor.peek(0)?.ok_or(ParseError::AbruptEnd)?.kind() {
+                        TokenKind::Punctuator(Punctuator::Assign) => {
+                            let default_init =
+                                Initializer::new(self.allow_in, self.allow_yield, self.allow_await)
+                                    .parse(cursor)?;
+                            patterns.push(BindingPatternTypeArray::BindingPattern {
+                                pattern: DeclarationPattern::Object(DeclarationPatternObject::new(
+                                    bindings,
+                                    Some(default_init),
+                                )),
+                            });
+                        }
+                        _ => {
+                            patterns.push(BindingPatternTypeArray::BindingPattern {
+                                pattern: DeclarationPattern::Object(DeclarationPatternObject::new(
+                                    bindings, None,
+                                )),
+                            });
+                        }
+                    }
+                }
+                TokenKind::Punctuator(Punctuator::OpenBracket) => {
+                    last_elision_or_first = false;
+
+                    let bindings =
+                        ArrayBindingPattern::new(self.allow_in, self.allow_yield, self.allow_await)
+                            .parse(cursor)?;
+
+                    match cursor.peek(0)?.ok_or(ParseError::AbruptEnd)?.kind() {
+                        TokenKind::Punctuator(Punctuator::Assign) => {
+                            let default_init =
+                                Initializer::new(self.allow_in, self.allow_yield, self.allow_await)
+                                    .parse(cursor)?;
+                            patterns.push(BindingPatternTypeArray::BindingPattern {
+                                pattern: DeclarationPattern::Array(DeclarationPatternArray::new(
+                                    bindings,
+                                    Some(default_init),
+                                )),
+                            });
+                        }
+                        _ => {
+                            patterns.push(BindingPatternTypeArray::BindingPattern {
+                                pattern: DeclarationPattern::Array(DeclarationPatternArray::new(
+                                    bindings, None,
+                                )),
+                            });
+                        }
+                    }
+                }
+                _ => {
+                    last_elision_or_first = false;
+
+                    let ident =
+                        BindingIdentifier::new(self.allow_yield, self.allow_await).parse(cursor)?;
+                    match cursor.peek(0)?.ok_or(ParseError::AbruptEnd)?.kind() {
+                        TokenKind::Punctuator(Punctuator::Assign) => {
+                            let default_init =
+                                Initializer::new(self.allow_in, self.allow_yield, self.allow_await)
+                                    .parse(cursor)?;
+                            patterns.push(BindingPatternTypeArray::SingleName {
+                                ident,
+                                default_init: Some(default_init),
+                            })
+                        }
+                        _ => {
+                            patterns.push(BindingPatternTypeArray::SingleName {
+                                ident,
+                                default_init: None,
+                            });
+                        }
+                    }
+                }
+            }
+
+            if let Some(peek_token) = cursor.peek(0)? {
+                if let TokenKind::Punctuator(Punctuator::Comma) = peek_token.kind() {
+                    cursor.expect(
+                        TokenKind::Punctuator(Punctuator::Comma),
+                        "array binding pattern",
+                    )?;
+                    if last_elision_or_first {
+                        patterns.push(BindingPatternTypeArray::Elision);
+                    } else {
+                        last_elision_or_first = true;
+                    }
+                }
+            }
+        }
+
+        Ok(patterns)
+    }
+}

boa/src/syntax/parser/statement/switch/tests.rs

@@ -151,8 +151,14 @@ fn check_seperated_switch() {
     check_parser(
         s,
         vec![
-            DeclarationList::Let(vec![Declaration::new("a", Node::from(Const::from(10)))].into())
+            DeclarationList::Let(
+                vec![Declaration::new_with_identifier(
+                    "a",
+                    Node::from(Const::from(10)),
+                )]
                 .into(),
+            )
+            .into(),
             Switch::new(
                 Identifier::from("a"),
                 vec![

boa/src/syntax/parser/statement/try_stm/tests.rs

@@ -20,7 +20,11 @@ fn check_inline_with_var_decl_inside_try() {
         "try { var x = 1; } catch(e) {}",
         vec![Try::new(
             vec![DeclarationList::Var(
-                vec![Declaration::new("x", Some(Const::from(1).into()))].into(),
+                vec![Declaration::new_with_identifier(
+                    "x",
+                    Some(Const::from(1).into()),
+                )]
+                .into(),
             )
             .into()],
             Some(Catch::new("e", vec![])),
@@ -36,13 +40,21 @@ fn check_inline_with_var_decl_inside_catch() {
         "try { var x = 1; } catch(e) { var x = 1; }",
         vec![Try::new(
             vec![DeclarationList::Var(
-                vec![Declaration::new("x", Some(Const::from(1).into()))].into(),
+                vec![Declaration::new_with_identifier(
+                    "x",
+                    Some(Const::from(1).into()),
+                )]
+                .into(),
             )
             .into()],
             Some(Catch::new(
                 "e",
                 vec![DeclarationList::Var(
-                    vec![Declaration::new("x", Some(Const::from(1).into()))].into(),
+                    vec![Declaration::new_with_identifier(
+                        "x",
+                        Some(Const::from(1).into()),
+                    )]
+                    .into(),
                 )
                 .into()],
             )),
@@ -81,7 +93,11 @@ fn check_inline_with_empty_try_var_decl_in_finally() {
             vec![],
             None,
             Some(Finally::from(vec![DeclarationList::Var(
-                vec![Declaration::new("x", Some(Const::from(1).into()))].into(),
+                vec![Declaration::new_with_identifier(
+                    "x",
+                    Some(Const::from(1).into()),
+                )]
+                .into(),
             )
             .into()])),
         )
@@ -98,7 +114,11 @@ fn check_inline_empty_try_paramless_catch() {
             Some(Catch::new::<_, Identifier, _>(
                 None,
                 vec![DeclarationList::Var(
-                    vec![Declaration::new("x", Some(Const::from(1).into()))].into(),
+                    vec![Declaration::new_with_identifier(
+                        "x",
+                        Some(Const::from(1).into()),
+                    )]
+                    .into(),
                 )
                 .into()],
             )),

boa/src/syntax/parser/statement/variable/mod.rs

@@ -7,6 +7,7 @@ use crate::{
             Keyword, Punctuator,
         },
         lexer::TokenKind,
+        parser::statement::{ArrayBindingPattern, ObjectBindingPattern},
         parser::{
             cursor::{Cursor, SemicolonResult},
             expression::Initializer,
@@ -167,20 +168,69 @@ where
     type Output = Declaration;
 
     fn parse(self, cursor: &mut Cursor<R>) -> Result<Self::Output, ParseError> {
-        // TODO: BindingPattern
+        let peek_token = cursor.peek(0)?.ok_or(ParseError::AbruptEnd)?;
-
+
-        let name = BindingIdentifier::new(self.allow_yield, self.allow_await).parse(cursor)?;
+        match peek_token.kind() {
-
+            TokenKind::Punctuator(Punctuator::OpenBlock) => {
-        let init = if let Some(t) = cursor.peek(0)? {
+                let bindings =
-            if *t.kind() == TokenKind::Punctuator(Punctuator::Assign) {
+                    ObjectBindingPattern::new(self.allow_in, self.allow_yield, self.allow_await)
-                Some(Initializer::new(true, self.allow_yield, self.allow_await).parse(cursor)?)
+                        .parse(cursor)?;
-            } else {
+
-                None
+                let init = if let Some(t) = cursor.peek(0)? {
+                    if *t.kind() == TokenKind::Punctuator(Punctuator::Assign) {
+                        Some(
+                            Initializer::new(self.allow_in, self.allow_yield, self.allow_await)
+                                .parse(cursor)?,
+                        )
+                    } else {
+                        None
+                    }
+                } else {
+                    None
+                };
+
+                Ok(Declaration::new_with_object_pattern(bindings, init))
+            }
+            TokenKind::Punctuator(Punctuator::OpenBracket) => {
+                let bindings =
+                    ArrayBindingPattern::new(self.allow_in, self.allow_yield, self.allow_await)
+                        .parse(cursor)?;
+
+                let init = if let Some(t) = cursor.peek(0)? {
+                    if *t.kind() == TokenKind::Punctuator(Punctuator::Assign) {
+                        Some(
+                            Initializer::new(self.allow_in, self.allow_yield, self.allow_await)
+                                .parse(cursor)?,
+                        )
+                    } else {
+                        None
+                    }
+                } else {
+                    None
+                };
+
+                Ok(Declaration::new_with_array_pattern(bindings, init))
             }
-        } else {
-            None
-        };
 
-        Ok(Declaration::new(name, init))
+            _ => {
+                let ident =
+                    BindingIdentifier::new(self.allow_yield, self.allow_await).parse(cursor)?;
+
+                let init = if let Some(t) = cursor.peek(0)? {
+                    if *t.kind() == TokenKind::Punctuator(Punctuator::Assign) {
+                        Some(
+                            Initializer::new(true, self.allow_yield, self.allow_await)
+                                .parse(cursor)?,
+                        )
+                    } else {
+                        None
+                    }
+                } else {
+                    None
+                };
+
+                Ok(Declaration::new_with_identifier(ident, init))
+            }
+        }
     }
 }

boa/src/syntax/parser/tests.rs

@@ -74,7 +74,7 @@ fn hoisting() {
             )
             .into(),
             DeclarationList::Var(
-                vec![Declaration::new(
+                vec![Declaration::new_with_identifier(
                     "a",
                     Node::from(Call::new(Identifier::from("hello"), vec![])),
                 )]
@@ -94,7 +94,7 @@ fn hoisting() {
         vec![
             Assign::new(Identifier::from("a"), Const::from(10)).into(),
             UnaryOp::new(op::UnaryOp::IncrementPost, Identifier::from("a")).into(),
-            DeclarationList::Var(vec![Declaration::new("a", None)].into()).into(),
+            DeclarationList::Var(vec![Declaration::new_with_identifier("a", None)].into()).into(),
         ],
     );
 }
@@ -144,7 +144,7 @@ fn comment_semi_colon_insertion() {
         s,
         vec![
             DeclarationList::Let(
-                vec![Declaration::new::<&str, Option<Node>>(
+                vec![Declaration::new_with_identifier::<&str, Option<Node>>(
                     "a",
                     Some(Const::Int(10).into()),
                 )]
@@ -152,7 +152,7 @@ fn comment_semi_colon_insertion() {
             )
             .into(),
             DeclarationList::Let(
-                vec![Declaration::new::<&str, Option<Node>>(
+                vec![Declaration::new_with_identifier::<&str, Option<Node>>(
                     "b",
                     Some(Const::Int(20).into()),
                 )]
@@ -176,7 +176,7 @@ fn multiline_comment_semi_colon_insertion() {
         s,
         vec![
             DeclarationList::Let(
-                vec![Declaration::new::<&str, Option<Node>>(
+                vec![Declaration::new_with_identifier::<&str, Option<Node>>(
                     "a",
                     Some(Const::Int(10).into()),
                 )]
@@ -184,7 +184,7 @@ fn multiline_comment_semi_colon_insertion() {
             )
             .into(),
             DeclarationList::Let(
-                vec![Declaration::new::<&str, Option<Node>>(
+                vec![Declaration::new_with_identifier::<&str, Option<Node>>(
                     "b",
                     Some(Const::Int(20).into()),
                 )]
@@ -205,7 +205,7 @@ fn multiline_comment_no_lineterminator() {
         s,
         vec![
             DeclarationList::Let(
-                vec![Declaration::new::<&str, Option<Node>>(
+                vec![Declaration::new_with_identifier::<&str, Option<Node>>(
                     "a",
                     Some(Const::Int(10).into()),
                 )]
@@ -213,7 +213,7 @@ fn multiline_comment_no_lineterminator() {
             )
             .into(),
             DeclarationList::Let(
-                vec![Declaration::new::<&str, Option<Node>>(
+                vec![Declaration::new_with_identifier::<&str, Option<Node>>(
                     "b",
                     Some(Const::Int(20).into()),
                 )]
@@ -237,7 +237,7 @@ fn assignment_line_terminator() {
         s,
         vec![
             DeclarationList::Let(
-                vec![Declaration::new::<&str, Option<Node>>(
+                vec![Declaration::new_with_identifier::<&str, Option<Node>>(
                     "a",
                     Some(Const::Int(3).into()),
                 )]
@@ -265,7 +265,7 @@ fn assignment_multiline_terminator() {
         s,
         vec![
             DeclarationList::Let(
-                vec![Declaration::new::<&str, Option<Node>>(
+                vec![Declaration::new_with_identifier::<&str, Option<Node>>(
                     "a",
                     Some(Const::Int(3).into()),
                 )]
@@ -328,8 +328,14 @@ fn empty_statement() {
         ",
         vec![
             Node::Empty,
-            DeclarationList::Var(vec![Declaration::new("a", Node::from(Const::from(10)))].into())
+            DeclarationList::Var(
+                vec![Declaration::new_with_identifier(
+                    "a",
+                    Node::from(Const::from(10)),
+                )]
                 .into(),
+            )
+            .into(),
             Node::If(If::new::<_, _, Node, _>(
                 Identifier::from("a"),
                 Node::Empty,