label statement implementation (#549)

Co-authored-by: Halid Odat <halidodat@gmail.com>

.vscode/tasks.json

@@ -35,27 +35,30 @@
       },
       "presentation": {
         "clear": true
-      }
+      },
+      "problemMatcher": []
     },
     {
       "type": "process",
       "label": "Get Tokens",
       "command": "cargo",
-      "args": ["run", "--", "-t=Debug", "./tests/js/test.js"],
+      "args": ["run", "--bin", "boa", "--", "-t=Debug", "./tests/js/test.js"],
       "group": "build",
       "presentation": {
         "clear": true
-      }
+      },
+      "problemMatcher": []
     },
     {
       "type": "process",
       "label": "Get AST",
       "command": "cargo",
-      "args": ["run", "--", "-a=Debug", "./tests/js/test.js"],
+      "args": ["run", "--bin", "boa", "--", "-a=Debug", "./tests/js/test.js"],
       "group": "build",
       "presentation": {
         "clear": true
-      }
+      },
+      "problemMatcher": []
     },
     {
       "type": "process",

boa/src/exec/break_node/mod.rs

@@ -11,7 +11,7 @@ impl Executable for Break {
     fn run(&self, interpreter: &mut Context) -> Result<Value> {
         interpreter
             .executor()
-            .set_current_state(InterpreterState::Break(self.label().map(String::from)));
+            .set_current_state(InterpreterState::Break(self.label().map(Box::from)));
 
         Ok(Value::undefined())
     }
@@ -21,7 +21,7 @@ impl Executable for Continue {
     fn run(&self, interpreter: &mut Context) -> Result<Value> {
         interpreter
             .executor()
-            .set_current_state(InterpreterState::Continue(self.label().map(String::from)));
+            .set_current_state(InterpreterState::Continue(self.label().map(Box::from)));
 
         Ok(Value::undefined())
     }

boa/src/exec/break_node/tests.rs

@@ -11,6 +11,6 @@ fn check_post_state() {
 
     assert_eq!(
         engine.executor().get_current_state(),
-        &InterpreterState::Break(Some("label".to_string()))
+        &InterpreterState::Break(Some("label".into()))
     );
 }

boa/src/exec/iteration/mod.rs

@@ -10,6 +10,27 @@ use crate::{
 #[cfg(test)]
 mod tests;
 
+// Checking labels for break and continue is the same operation for `ForLoop`, `While` and `DoWhile`
+macro_rules! handle_state_with_labels {
+    ($self:ident, $label:ident, $interpreter:ident, $state:tt) => {{
+        if let Some(brk_label) = $label {
+            if let Some(stmt_label) = $self.label() {
+                // Break from where we are, keeping "continue" set as the state
+                if stmt_label != brk_label.as_ref() {
+                    break;
+                }
+            } else {
+                // if a label is set but the current block has no label, break
+                break;
+            }
+        }
+
+        $interpreter
+            .executor()
+            .set_current_state(InterpreterState::Executing);
+    }};
+}
+
 impl Executable for ForLoop {
     fn run(&self, interpreter: &mut Context) -> Result<Value> {
         // Create the block environment.
@@ -34,22 +55,14 @@ impl Executable for ForLoop {
             let result = self.body().run(interpreter)?;
 
             match interpreter.executor().get_current_state() {
-                InterpreterState::Break(_label) => {
-                    // TODO break to label.
-
-                    // Loops 'consume' breaks.
-                    interpreter
-                        .executor()
-                        .set_current_state(InterpreterState::Executing);
+                InterpreterState::Break(label) => {
+                    handle_state_with_labels!(self, label, interpreter, break);
                     break;
                 }
-                InterpreterState::Continue(_label) => {
-                    // TODO continue to label.
-                    interpreter
-                        .executor()
-                        .set_current_state(InterpreterState::Executing);
-                    // after breaking out of the block, continue execution of the loop
+                InterpreterState::Continue(label) => {
+                    handle_state_with_labels!(self, label, interpreter, continue);
                 }
+
                 InterpreterState::Return => {
                     return Ok(result);
                 }
@@ -76,21 +89,12 @@ impl Executable for WhileLoop {
         while self.cond().run(interpreter)?.to_boolean() {
             result = self.expr().run(interpreter)?;
             match interpreter.executor().get_current_state() {
-                InterpreterState::Break(_label) => {
-                    // TODO break to label.
-
-                    // Loops 'consume' breaks.
-                    interpreter
-                        .executor()
-                        .set_current_state(InterpreterState::Executing);
+                InterpreterState::Break(label) => {
+                    handle_state_with_labels!(self, label, interpreter, break);
                     break;
                 }
-                InterpreterState::Continue(_label) => {
-                    // TODO continue to label.
-                    interpreter
-                        .executor()
-                        .set_current_state(InterpreterState::Executing);
-                    // after breaking out of the block, continue execution of the loop
+                InterpreterState::Continue(label) => {
+                    handle_state_with_labels!(self, label, interpreter, continue)
                 }
                 InterpreterState::Return => {
                     return Ok(result);

boa/src/exec/iteration/tests.rs

@@ -191,3 +191,38 @@ fn do_while_loop_continue() {
     "#;
     assert_eq!(&exec(scenario), "[ 1, 2 ]");
 }
+
+#[test]
+fn for_loop_break_label() {
+    let scenario = r#"
+        var str = "";
+
+        outer: for (let i = 0; i < 5; i++) {
+            inner: for (let b = 0; b < 5; b++) {
+                if (b === 2) {
+                break outer;
+                }
+                str = str + b;
+            }
+            str = str + i;
+        }
+        str
+    "#;
+    assert_eq!(&exec(scenario), "\"01\"")
+}
+
+#[test]
+fn for_loop_continue_label() {
+    let scenario = r#"
+    var count = 0;
+    label: for (let x = 0; x < 10;) {
+        while (true) {
+            x++;
+            count++;
+            continue label;
+        }
+    }
+    count
+    "#;
+    assert_eq!(&exec(scenario), "10");
+}

boa/src/exec/mod.rs

@@ -36,8 +36,8 @@ pub trait Executable {
 pub(crate) enum InterpreterState {
     Executing,
     Return,
-    Break(Option<String>),
-    Continue(Option<String>),
+    Break(Option<Box<str>>),
+    Continue(Option<Box<str>>),
 }
 
 /// A Javascript intepreter

boa/src/exec/tests.rs

@@ -1330,7 +1330,7 @@ fn assign_to_object_decl() {
     let mut engine = Context::new();
 
     const ERR_MSG: &str =
-        "Uncaught \"SyntaxError\": \"expected token \';\', got \':\' in expression statement at line 1, col 3\"";
+        "Uncaught \"SyntaxError\": \"unexpected token '=', primary expression at line 1, col 8\"";
 
     assert_eq!(forward(&mut engine, "{a: 3} = {a: 5};"), ERR_MSG);
 }

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

@@ -21,6 +21,7 @@ use serde::{Deserialize, Serialize};
 pub struct ForLoop {
     #[cfg_attr(feature = "serde", serde(flatten))]
     inner: Box<InnerForLoop>,
+    label: Option<Box<str>>,
 }
 
 impl ForLoop {
@@ -34,6 +35,7 @@ impl ForLoop {
     {
         Self {
             inner: Box::new(InnerForLoop::new(init, condition, final_expr, body)),
+            label: None,
         }
     }
 
@@ -76,6 +78,14 @@ impl ForLoop {
 
         write!(f, "}}")
     }
+
+    pub fn label(&self) -> Option<&str> {
+        self.label.as_ref().map(Box::as_ref)
+    }
+
+    pub fn set_label(&mut self, label: Box<str>) {
+        self.label = Some(label);
+    }
 }
 
 impl fmt::Display for ForLoop {
@@ -154,6 +164,7 @@ impl InnerForLoop {
 pub struct WhileLoop {
     cond: Box<Node>,
     expr: Box<Node>,
+    label: Option<Box<str>>,
 }
 
 impl WhileLoop {
@@ -165,6 +176,10 @@ impl WhileLoop {
         &self.expr
     }
 
+    pub fn label(&self) -> Option<&str> {
+        self.label.as_ref().map(Box::as_ref)
+    }
+
     /// Creates a `WhileLoop` AST node.
     pub fn new<C, B>(condition: C, body: B) -> Self
     where
@@ -174,6 +189,7 @@ impl WhileLoop {
         Self {
             cond: Box::new(condition.into()),
             expr: Box::new(body.into()),
+            label: None,
         }
     }
 
@@ -212,6 +228,7 @@ impl From<WhileLoop> for Node {
 pub struct DoWhileLoop {
     body: Box<Node>,
     cond: Box<Node>,
+    label: Option<Box<str>>,
 }
 
 impl DoWhileLoop {
@@ -223,6 +240,10 @@ impl DoWhileLoop {
         &self.cond
     }
 
+    pub fn label(&self) -> Option<&str> {
+        self.label.as_ref().map(Box::as_ref)
+    }
+
     /// Creates a `DoWhileLoop` AST node.
     pub fn new<B, C>(body: B, condition: C) -> Self
     where
@@ -232,6 +253,7 @@ impl DoWhileLoop {
         Self {
             body: Box::new(body.into()),
             cond: Box::new(condition.into()),
+            label: None,
         }
     }
 

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

@@ -0,0 +1,66 @@
+use std::io::Read;
+
+use super::{LabelIdentifier, Statement};
+use crate::{
+    syntax::ast::Node,
+    syntax::{
+        ast::Punctuator,
+        parser::{
+            cursor::Cursor, error::ParseError, AllowAwait, AllowReturn, AllowYield, TokenParser,
+        },
+    },
+    BoaProfiler,
+};
+/// Labelled Statement Parsing
+///
+/// More information
+/// - [MDN documentation][mdn]
+/// - [ECMAScript specification][spec]
+///
+/// [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/label
+/// [spec]: https://tc39.es/ecma262/#sec-labelled-statements
+#[derive(Debug, Clone, Copy)]
+pub(super) struct LabelledStatement {
+    allow_yield: AllowYield,
+    allow_await: AllowAwait,
+    allow_return: AllowReturn,
+}
+
+impl LabelledStatement {
+    pub(super) fn new<Y, A, R>(allow_yield: Y, allow_await: A, allow_return: R) -> Self
+    where
+        Y: Into<AllowYield>,
+        A: Into<AllowAwait>,
+        R: Into<AllowReturn>,
+    {
+        Self {
+            allow_yield: allow_yield.into(),
+            allow_await: allow_await.into(),
+            allow_return: allow_return.into(),
+        }
+    }
+}
+
+impl<R> TokenParser<R> for LabelledStatement
+where
+    R: Read,
+{
+    type Output = Node;
+
+    fn parse(self, cursor: &mut Cursor<R>) -> Result<Self::Output, ParseError> {
+        let _timer = BoaProfiler::global().start_event("Label", "Parsing");
+        let name = LabelIdentifier::new(self.allow_yield, self.allow_await).parse(cursor)?;
+        cursor.expect(Punctuator::Colon, "Labelled Statement")?;
+        let mut stmt =
+            Statement::new(self.allow_yield, self.allow_await, self.allow_return).parse(cursor)?;
+
+        set_label_for_node(&mut stmt, name);
+        Ok(stmt)
+    }
+}
+
+fn set_label_for_node(stmt: &mut Node, name: Box<str>) {
+    if let Node::ForLoop(ref mut for_loop) = stmt {
+        for_loop.set_label(name)
+    }
+}

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

@@ -14,6 +14,7 @@ mod declaration;
 mod expression;
 mod if_stm;
 mod iteration;
+mod labelled_stm;
 mod return_stm;
 mod switch;
 mod throw;
@@ -37,11 +38,12 @@ use self::{
 
 use super::{AllowAwait, AllowReturn, AllowYield, Cursor, ParseError, TokenParser};
 
-use crate::syntax::lexer::TokenKind;
+use crate::syntax::lexer::{InputElement, TokenKind};
 use crate::{
     syntax::ast::{node, Keyword, Node, Punctuator},
     BoaProfiler,
 };
+use labelled_stm::LabelledStatement;
 
 use std::io::Read;
 
@@ -170,7 +172,28 @@ where
                     .parse(cursor)
                     .map(Node::from)
             }
-            // TODO: https://tc39.es/ecma262/#prod-LabelledStatement
+            TokenKind::Identifier(_) => {
+                // Labelled Statement check
+                cursor.set_goal(InputElement::Div);
+                let tok = cursor.peek(1)?;
+                if tok.is_some()
+                    && matches!(
+                        tok.unwrap().kind(),
+                        TokenKind::Punctuator(Punctuator::Colon)
+                    )
+                {
+                    return LabelledStatement::new(
+                        self.allow_yield,
+                        self.allow_await,
+                        self.allow_return,
+                    )
+                    .parse(cursor)
+                    .map(Node::from);
+                }
+
+                ExpressionStatement::new(self.allow_yield, self.allow_await).parse(cursor)
+            }
+
             _ => ExpressionStatement::new(self.allow_yield, self.allow_await).parse(cursor),
         }
     }
@@ -367,7 +390,7 @@ where
 ///  - [ECMAScript specification][spec]
 ///
 /// [spec]: https://tc39.es/ecma262/#prod-LabelIdentifier
-type LabelIdentifier = BindingIdentifier;
+pub(super) type LabelIdentifier = BindingIdentifier;
 
 /// Binding identifier parsing.
 ///