Implement bare Array object with prototype field (#51)

* First draft of Array prototype object

* First draft of Array prototype object

* Update to working Array object

* Remove unneeded HashMap import

* Fix indexing by removing private internal HashMap

* Fix formatting issues with cargo fmt

src/bin/bin.rs

@@ -1,14 +1,16 @@
 extern crate boa;
 use boa::exec;
-use std::fs::read_to_string;
 use std::env;
+use std::fs::read_to_string;
 use std::process::exit;
 
 fn print_usage() {
-    println!("Usage:
+    println!(
+        "Usage:
 boa [file.js]
     Interpret and execute file.js
-    (if no file given, defaults to tests/js/test.js");
+    (if no file given, defaults to tests/js/test.js"
+    );
 }
 
 pub fn main() -> Result<(), std::io::Error> {
@@ -19,7 +21,7 @@ pub fn main() -> Result<(), std::io::Error> {
         // No arguments passed, default to "test.js"
         1 => {
             read_file = "tests/js/test.js";
-        },
+        }
         // One argument passed, assumed this is the test file
         2 => {
             read_file = &args[1];

src/lib/environment/environment_record_trait.rs

@@ -3,7 +3,7 @@
 //! https://tc39.github.io/ecma262/#sec-environment-records
 //! https://tc39.github.io/ecma262/#sec-lexical-environments
 //!
-//! Some environments are stored as JSObjects. This is for GC, i.e we want to keep an environment if a variable is closed-over (a closure is returned).   
+//! Some environments are stored as JSObjects. This is for GC, i.e we want to keep an environment if a variable is closed-over (a closure is returned).
 //! All of the logic to handle scope/environment records are stored in here.
 //!
 //! There are 5 Environment record kinds. They all have methods in common, these are implemented as a the `EnvironmentRecordTrait`

src/lib/js/array.rs

@@ -1,19 +1,56 @@
 use crate::js::function::NativeFunctionData;
-use crate::js::value::{to_value, ResultValue, Value, ValueData};
+use crate::js::object::{Property, PROTOTYPE};
+use crate::js::value::{from_value, to_value, ResultValue, Value, ValueData};
 use gc::Gc;
 
 /// Create a new array
-pub fn make_array(this: Value, _: Value, _: Vec<Value>) -> ResultValue {
+pub fn make_array(this: Value, _: Value, args: Vec<Value>) -> ResultValue {
     let this_ptr = this.clone();
-    this_ptr.set_field_slice("length", to_value(0i32));
-    Ok(Gc::new(ValueData::Undefined))
+    // Make a new Object which will internally represent the Array (mapping
+    // between indices and values): this creates an Object with no prototype
+    match args.len() {
+        0 => {
+            this_ptr.set_field_slice("length", to_value(0i32));
+        }
+        1 => {
+            let length_chosen: i32 = from_value(args[0].clone()).unwrap();
+            this_ptr.set_field_slice("length", to_value(length_chosen));
+        }
+        n => {
+            this_ptr.set_field_slice("length", to_value(n));
+            for k in 0..n {
+                let index_str = k.to_string();
+                this_ptr.set_field(index_str, args[k].clone());
+            }
+        }
+    }
+    Ok(this_ptr)
 }
+
+/// Get an array's length
+pub fn get_array_length(this: Value, _: Value, _: Vec<Value>) -> ResultValue {
+    // Access the inner hash map which represents the actual Array contents
+    // (mapping between indices and values)
+    Ok(this.get_field_slice("length"))
+}
+
 /// Create a new `Array` object
-pub fn _create() -> Value {
+pub fn _create(global: &Value) -> Value {
     let array = to_value(make_array as NativeFunctionData);
+    let proto = ValueData::new_obj(Some(global));
+    let length = Property {
+        configurable: false,
+        enumerable: false,
+        writable: false,
+        value: Gc::new(ValueData::Undefined),
+        get: to_value(get_array_length as NativeFunctionData),
+        set: Gc::new(ValueData::Undefined),
+    };
+    proto.set_prop_slice("length", length);
+    array.set_field_slice(PROTOTYPE, proto);
     array
 }
 /// Initialise the global object with the `Array` object
 pub fn init(global: &Value) {
-    global.set_field_slice("Array", _create());
+    global.set_field_slice("Array", _create(global));
 }

src/lib/js/string.rs

@@ -2,8 +2,8 @@ use crate::js::function::NativeFunctionData;
 use crate::js::object::{Property, PROTOTYPE};
 use crate::js::value::{from_value, to_value, ResultValue, Value, ValueData};
 use gc::Gc;
+use std::cmp::{max, min};
 use std::f64::NAN;
-use std::cmp::{min, max};
 
 /// Create new string
 /// https://searchfox.org/mozilla-central/source/js/src/vm/StringObject.h#19
@@ -82,7 +82,7 @@ pub fn char_code_at(this: Value, _: Value, args: Vec<Value>) -> ResultValue {
 /// arguments
 /// https://tc39.github.io/ecma262/#sec-string.prototype.concat
 pub fn concat(this: Value, _: Value, args: Vec<Value>) -> ResultValue {
-    //        ^^ represents instance  ^^ represents arguments 
+    //        ^^ represents instance  ^^ represents arguments
     // First we get it the actual string a private field stored on the object only the engine has access to.
     // Then we convert it into a Rust String by wrapping it in from_value
     let primitive_val: String =
@@ -129,8 +129,16 @@ pub fn slice(this: Value, _: Value, args: Vec<Value>) -> ResultValue {
     // Note that this is an O(N) operation (because UTF-8 is complex) while getting the number of bytes is an O(1) operation.
     let length: i32 = primitive_val.chars().count() as i32;
 
-    let from: i32 = if start < 0 {max(length + start, 0)} else {min(start, length)};
-    let to: i32 = if end < 0 {max(length + end, 0)} else {min(end, length)};
+    let from: i32 = if start < 0 {
+        max(length + start, 0)
+    } else {
+        min(start, length)
+    };
+    let to: i32 = if end < 0 {
+        max(length + end, 0)
+    } else {
+        min(end, length)
+    };
 
     let span = max(to - from, 0);
 
@@ -159,8 +167,11 @@ pub fn starts_with(this: Value, _: Value, args: Vec<Value>) -> ResultValue {
     let search_length: i32 = search_string.chars().count() as i32;
 
     // If less than 2 args specified, position is 'undefined', defaults to 0
-    let position: i32 = if args.len() < 2 {0} 
-                        else {from_value(args[1].clone()).unwrap()};
+    let position: i32 = if args.len() < 2 {
+        0
+    } else {
+        from_value(args[1].clone()).unwrap()
+    };
 
     let start = min(max(position, 0), length);
     let end = start + search_length;
@@ -169,8 +180,7 @@ pub fn starts_with(this: Value, _: Value, args: Vec<Value>) -> ResultValue {
         Ok(to_value(false))
     } else {
         // Only use the part of the string from "start"
-        let this_string: String = primitive_val.chars()
-            .skip(start as usize).collect();
+        let this_string: String = primitive_val.chars().skip(start as usize).collect();
         Ok(to_value(this_string.starts_with(&search_string)))
     }
 }
@@ -194,8 +204,11 @@ pub fn ends_with(this: Value, _: Value, args: Vec<Value>) -> ResultValue {
 
     // If less than 2 args specified, end_position is 'undefined', defaults to
     // length of this
-    let end_position: i32 = if args.len() < 2 {length} 
-                            else {from_value(args[1].clone()).unwrap()};
+    let end_position: i32 = if args.len() < 2 {
+        length
+    } else {
+        from_value(args[1].clone()).unwrap()
+    };
 
     let end = min(max(end_position, 0), length);
     let start = end - search_length;
@@ -204,8 +217,7 @@ pub fn ends_with(this: Value, _: Value, args: Vec<Value>) -> ResultValue {
         Ok(to_value(false))
     } else {
         // Only use the part of the string up to "end"
-        let this_string: String = primitive_val.chars()
-            .take(end as usize).collect();
+        let this_string: String = primitive_val.chars().take(end as usize).collect();
         Ok(to_value(this_string.ends_with(&search_string)))
     }
 }
@@ -228,14 +240,16 @@ pub fn includes(this: Value, _: Value, args: Vec<Value>) -> ResultValue {
     let length: i32 = primitive_val.chars().count() as i32;
 
     // If less than 2 args specified, position is 'undefined', defaults to 0
-    let position: i32 = if args.len() < 2 {0} 
-                        else {from_value(args[1].clone()).unwrap()};
+    let position: i32 = if args.len() < 2 {
+        0
+    } else {
+        from_value(args[1].clone()).unwrap()
+    };
 
     let start = min(max(position, 0), length);
 
     // Take the string from "this" and use only the part of it after "start"
-    let this_string: String = primitive_val.chars()
-        .skip(start as usize).collect();
+    let this_string: String = primitive_val.chars().skip(start as usize).collect();
 
     Ok(to_value(this_string.contains(&search_string)))
 }
@@ -244,7 +258,7 @@ pub fn includes(this: Value, _: Value, args: Vec<Value>) -> ResultValue {
 /// object to a String, at one or more indices that are greater than or equal to
 /// position, then the smallest such index is returned; otherwise, -1 is
 /// returned. If position is undefined, 0 is assumed, so as to search all of the
-/// String. 
+/// String.
 /// https://tc39.github.io/ecma262/#sec-string.prototype.includes
 pub fn index_of(this: Value, _: Value, args: Vec<Value>) -> ResultValue {
     //          ^^ represents instance  ^^ represents arguments)
@@ -259,8 +273,11 @@ pub fn index_of(this: Value, _: Value, args: Vec<Value>) -> ResultValue {
     let length: i32 = primitive_val.chars().count() as i32;
 
     // If less than 2 args specified, position is 'undefined', defaults to 0
-    let position: i32 = if args.len() < 2 {0} 
-                        else {from_value(args[1].clone()).unwrap()};
+    let position: i32 = if args.len() < 2 {
+        0
+    } else {
+        from_value(args[1].clone()).unwrap()
+    };
 
     let start = min(max(position, 0), length);
 
@@ -269,11 +286,10 @@ pub fn index_of(this: Value, _: Value, args: Vec<Value>) -> ResultValue {
     // Instead, iterate over the part we're checking until the slice we're
     // checking "starts with" the search string
     for index in start..length {
-        let this_string: String = primitive_val.chars()
-            .skip(index as usize).collect();
+        let this_string: String = primitive_val.chars().skip(index as usize).collect();
         if this_string.starts_with(&search_string) {
             // Explicitly return early with the index value
-            return Ok(to_value(index))
+            return Ok(to_value(index));
         }
     }
     // Didn't find a match, so return -1
@@ -299,8 +315,11 @@ pub fn last_index_of(this: Value, _: Value, args: Vec<Value>) -> ResultValue {
     let length: i32 = primitive_val.chars().count() as i32;
 
     // If less than 2 args specified, position is 'undefined', defaults to 0
-    let position: i32 = if args.len() < 2 {0} 
-                        else {from_value(args[1].clone()).unwrap()};
+    let position: i32 = if args.len() < 2 {
+        0
+    } else {
+        from_value(args[1].clone()).unwrap()
+    };
 
     let start = min(max(position, 0), length);
 
@@ -310,8 +329,7 @@ pub fn last_index_of(this: Value, _: Value, args: Vec<Value>) -> ResultValue {
     // index we found that "starts with" the search string
     let mut highest_index: i32 = -1;
     for index in start..length {
-        let this_string: String = primitive_val.chars()
-            .skip(index as usize).collect();
+        let this_string: String = primitive_val.chars().skip(index as usize).collect();
         if this_string.starts_with(&search_string) {
             highest_index = index;
         }
@@ -332,7 +350,7 @@ fn is_trimmable_whitespace(c: char) -> bool {
         // Explicit whitespace: https://tc39.es/ecma262/#sec-white-space
         '\u{0009}' | '\u{000B}' | '\u{000C}' | '\u{0020}' | '\u{00A0}' | '\u{FEFF}' => true,
         // Unicode Space_Seperator category
-        '\u{1680}' | '\u{2000}'..='\u{200A}' | '\u{202F}' | '\u{205F}' | '\u{3000}'  => true,
+        '\u{1680}' | '\u{2000}'..='\u{200A}' | '\u{202F}' | '\u{205F}' | '\u{3000}' => true,
         // Line terminators: https://tc39.es/ecma262/#sec-line-terminators
         '\u{000A}' | '\u{000D}' | '\u{2028}' | '\u{2029}' => true,
         _ => false,
@@ -348,7 +366,9 @@ pub fn trim(this: Value, _: Value, _: Vec<Value>) -> ResultValue {
 pub fn trim_start(this: Value, _: Value, _: Vec<Value>) -> ResultValue {
     let this_str: String =
         from_value(this.get_private_field(String::from("PrimitiveValue"))).unwrap();
-    Ok(to_value(this_str.trim_start_matches(is_trimmable_whitespace)))
+    Ok(to_value(
+        this_str.trim_start_matches(is_trimmable_whitespace),
+    ))
 }
 
 pub fn trim_end(this: Value, _: Value, _: Vec<Value>) -> ResultValue {

src/lib/syntax/ast/token.rs

@@ -1,7 +1,7 @@
-use std::fmt::{Debug, Display, Formatter, Result};
 use crate::syntax::ast::keyword::Keyword;
 use crate::syntax::ast::pos::Position;
 use crate::syntax::ast::punc::Punctuator;
+use std::fmt::{Debug, Display, Formatter, Result};
 
 #[derive(Clone, PartialEq)]
 /// Represents a token