sdk/lib/_internal/js_dev_runtime/private/js_array.dart - sdk.git - Git at Google

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.

 part of dart._interceptors;

 /**
  * The interceptor class for [List]. The compiler recognizes this
  * class as an interceptor, and changes references to [:this:] to
  * actually use the receiver of the method, which is generated as an extra
  * argument added to each member.
  */
 @JsPeerInterface(name: 'Array')
 class JSArray<E> implements List<E>, JSIndexable<E> {
   const JSArray();

   /**
    * Constructor for adding type parameters to an existing JavaScript
    * Array. Used for creating literal lists.
    */
   factory JSArray.of(list) {
     // TODO(sra): Move this to core.List for better readability.
     //
     // TODO(jmesserly): this uses special compiler magic to close over the
     // parameterized ES6 'JSArray' class.
     JS('', '#.__proto__ = JSArray.prototype', list);
     return JS('-dynamic', '#', list);
   }

   // TODO(jmesserly): consider a fixed array subclass instead.
   factory JSArray.fixed(list) {
     JS('', '#.__proto__ = JSArray.prototype', list);
     JS('', r'#.fixed$length = Array', list);
     return JS('-dynamic', '#', list);
   }

   factory JSArray.unmodifiable(list) {
     JS('', '#.__proto__ = JSArray.prototype', list);
     JS('', r'#.fixed$length = Array', list);
     JS('', r'#.immutable$list = Array', list);
     return JS('-dynamic', '#', list);
   }

   static void markFixedList(list) {
     // Functions are stored in the hidden class and not as properties in
     // the object. We never actually look at the value, but only want
     // to know if the property exists.
     JS('', r'#.fixed$length = Array', list);
   }

   static void markUnmodifiableList(list) {
     // Functions are stored in the hidden class and not as properties in
     // the object. We never actually look at the value, but only want
     // to know if the property exists.
     JS('', r'#.fixed$length = Array', list);
     JS('', r'#.immutable$list = Array', list);
   }

   checkMutable(reason) {
     if (JS<bool>('!', r'#.immutable$list', this)) {
       throw UnsupportedError(reason);
     }
   }

   checkGrowable(reason) {
     if (JS<bool>('!', r'#.fixed$length', this)) {
       throw UnsupportedError(reason);
     }
   }

   List<R> cast<R>() => List.castFrom<E, R>(this);
   void add(E value) {
     checkGrowable('add');
     JS('void', r'#.push(#)', this, value);
   }

   E removeAt(@nullCheck int index) {
     checkGrowable('removeAt');
     if (index < 0 || index >= length) {
       throw RangeError.value(index);
     }
     return JS('-dynamic', r'#.splice(#, 1)[0]', this, index);
   }

   void insert(@nullCheck int index, E value) {
     checkGrowable('insert');
     if (index < 0 || index > length) {
       throw RangeError.value(index);
     }
     JS('void', r'#.splice(#, 0, #)', this, index, value);
   }

   void insertAll(@nullCheck int index, Iterable<E> iterable) {
     checkGrowable('insertAll');
     RangeError.checkValueInInterval(index, 0, this.length, "index");
     if (iterable is! EfficientLengthIterable) {
       iterable = iterable.toList();
     }
     @nullCheck
     int insertionLength = iterable.length;
     this._setLengthUnsafe(this.length + insertionLength);
     int end = index + insertionLength;
     this.setRange(end, this.length, this, index);
     this.setRange(index, end, iterable);
   }

   void setAll(@nullCheck int index, Iterable<E> iterable) {
     checkMutable('setAll');
     RangeError.checkValueInInterval(index, 0, this.length, "index");
     for (var element in iterable) {
       this[index++] = element;
     }
   }

   E removeLast() {
     checkGrowable('removeLast');
     if (length == 0) throw diagnoseIndexError(this, -1);
     return JS('var', r'#.pop()', this);
   }

   bool remove(Object? element) {
     checkGrowable('remove');
     var length = this.length;
     for (int i = 0; i < length; i++) {
       if (this[i] == element) {
         JS('var', r'#.splice(#, 1)', this, i);
         return true;
       }
     }
     return false;
   }

   /**
    * Removes elements matching [test] from [this] List.
    */
   void removeWhere(bool Function(E) test) {
     checkGrowable('removeWhere');
     _removeWhere(test, true);
   }

   void retainWhere(bool Function(E) test) {
     checkGrowable('retainWhere');
     _removeWhere(test, false);
   }

   void _removeWhere(bool Function(E) test, bool removeMatching) {
     // Performed in two steps, to avoid exposing an inconsistent state
     // to the [test] function. First the elements to retain are found, and then
     // the original list is updated to contain those elements.

     // TODO(sra): Replace this algorithm with one that retains a list of ranges
     // to be removed.  Most real uses remove 0, 1 or a few clustered elements.

     List retained = [];
     int end = this.length;
     for (int i = 0; i < end; i++) {
       var element = JS<E>('', '#[#]', this, i);
       // !test() ensures bool conversion in checked mode.
       if (!test(element) == removeMatching) {
         // Unsafe add here to avoid extra casts and growable checks enforced by
         // the exposed add method.
         JS('', '#.push(#)', retained, element);
       }
       if (this.length != end) throw ConcurrentModificationError(this);
     }
     if (retained.length == end) return;
     this.length = retained.length;
     @nullCheck
     var length = retained.length;
     for (int i = 0; i < length; i++) {
       JS('', '#[#] = #[#]', this, i, retained, i);
     }
   }

   Iterable<E> where(bool Function(E) f) {
     return WhereIterable<E>(this, f);
   }

   Iterable<T> expand<T>(Iterable<T> Function(E) f) {
     return ExpandIterable<E, T>(this, f);
   }

   void addAll(Iterable<E> collection) {
     int i = this.length;
     checkGrowable('addAll');
     for (E e in collection) {
       assert(i == this.length || (throw ConcurrentModificationError(this)));
       i++;
       JS('void', r'#.push(#)', this, e);
     }
   }

   void clear() {
     length = 0;
   }

   void forEach(void Function(E) f) {
     int end = this.length;
     for (int i = 0; i < end; i++) {
       var element = JS<E>('', '#[#]', this, i);
       f(element);
       if (this.length != end) throw ConcurrentModificationError(this);
     }
   }

   Iterable<T> map<T>(T Function(E) f) {
     return MappedListIterable<E, T>(this, f);
   }

   String join([String separator = ""]) {
     var length = this.length;
     var list = List<String>.filled(length, "");
     for (int i = 0; i < length; i++) {
       list[i] = "${this[i]}";
     }
     return JS<String>('!', "#.join(#)", list, separator);
   }

   Iterable<E> take(int n) {
     return SubListIterable<E>(this, 0, n);
   }

   Iterable<E> takeWhile(bool test(E value)) {
     return TakeWhileIterable<E>(this, test);
   }

   Iterable<E> skip(int n) {
     return SubListIterable<E>(this, n, null);
   }

   Iterable<E> skipWhile(bool Function(E) test) {
     return SkipWhileIterable<E>(this, test);
   }

   E reduce(E combine(E previousValue, E element)) {
     int length = this.length;
     if (length == 0) throw IterableElementError.noElement();
     E value = this[0];
     for (int i = 1; i < length; i++) {
       var element = JS<E>('', '#[#]', this, i);
       value = combine(value, element);
       if (length != this.length) throw ConcurrentModificationError(this);
     }
     return value;
   }

   T fold<T>(T initialValue, T Function(T previousValue, E element) combine) {
     var value = initialValue;
     int length = this.length;
     for (int i = 0; i < length; i++) {
       var element = JS<E>('', '#[#]', this, i);
       value = combine(value, element);
       if (this.length != length) throw ConcurrentModificationError(this);
     }
     return value;
   }

   E firstWhere(bool Function(E) test, {E Function()? orElse}) {
     int end = this.length;
     for (int i = 0; i < end; ++i) {
       var element = JS<E>('', '#[#]', this, i);
       if (test(element)) return element;
       if (this.length != end) throw ConcurrentModificationError(this);
     }
     if (orElse != null) return orElse();
     throw IterableElementError.noElement();
   }

   E lastWhere(bool Function(E) test, {E Function()? orElse}) {
     int length = this.length;
     for (int i = length - 1; i >= 0; i--) {
       var element = JS<E>('', '#[#]', this, i);
       if (test(element)) return element;
       if (length != this.length) {
         throw ConcurrentModificationError(this);
       }
     }
     if (orElse != null) return orElse();
     throw IterableElementError.noElement();
   }

   E singleWhere(bool Function(E) test, {E Function()? orElse}) {
     int length = this.length;
     E? match = null;
     bool matchFound = false;
     for (int i = 0; i < length; i++) {
       var element = JS<E>('', '#[#]', this, i);
       if (test(element)) {
         if (matchFound) {
           throw IterableElementError.tooMany();
         }
         matchFound = true;
         match = element;
       }
       if (length != this.length) {
         throw ConcurrentModificationError(this);
       }
     }
     if (matchFound) return match as E;
     if (orElse != null) return orElse();
     throw IterableElementError.noElement();
   }

   E elementAt(int index) {
     return this[index];
   }

   List<E> sublist(@nullCheck int start, [int? end]) {
     if (start < 0 || start > length) {
       throw RangeError.range(start, 0, length, "start");
     }
     if (end == null) {
       end = length;
     } else {
       @notNull
       var _end = end;
       if (_end < start || _end > length) {
         throw RangeError.range(end, start, length, "end");
       }
     }
     if (start == end) return <E>[];
     return JSArray<E>.of(JS('', r'#.slice(#, #)', this, start, end));
   }

   Iterable<E> getRange(int start, int end) {
     RangeError.checkValidRange(start, end, this.length);
     return SubListIterable<E>(this, start, end);
   }

   E get first {
     if (length > 0) return this[0];
     throw IterableElementError.noElement();
   }

   E get last {
     if (length > 0) return this[length - 1];
     throw IterableElementError.noElement();
   }

   E get single {
     if (length == 1) return this[0];
     if (length == 0) throw IterableElementError.noElement();
     throw IterableElementError.tooMany();
   }

   void removeRange(@nullCheck int start, @nullCheck int end) {
     checkGrowable('removeRange');
     RangeError.checkValidRange(start, end, this.length);
     int deleteCount = end - start;
     JS('', '#.splice(#, #)', this, start, deleteCount);
   }

   void setRange(@nullCheck int start, @nullCheck int end, Iterable<E> iterable,
       [@nullCheck int skipCount = 0]) {
     checkMutable('set range');

     RangeError.checkValidRange(start, end, this.length);
     int length = end - start;
     if (length == 0) return;
     RangeError.checkNotNegative(skipCount, "skipCount");

     var otherList = <E>[];
     int otherStart = 0;
     // TODO(floitsch): Make this accept more.
     if (iterable is List<E>) {
       otherList = iterable;
       otherStart = skipCount;
     } else {
       otherList = iterable.skip(skipCount).toList(growable: false);
       otherStart = 0;
     }
     if (otherStart + length > otherList.length) {
       throw IterableElementError.tooFew();
     }
     if (otherStart < start) {
       // Copy backwards to ensure correct copy if [from] is this.
       // TODO(sra): If [from] is the same Array as [this], we can copy without
       // type annotation checks on the stores.
       for (int i = length - 1; i >= 0; i--) {
         // Use JS to avoid bounds check (the bounds check elimination
         // optimzation is too weak). The 'E' type annotation is a store type
         // check - we can't rely on iterable, it could be List<dynamic>.
         var element = otherList[otherStart + i];
         JS('', '#[#] = #', this, start + i, element);
       }
     } else {
       for (int i = 0; i < length; i++) {
         var element = otherList[otherStart + i];
         JS('', '#[#] = #', this, start + i, element);
       }
     }
   }

   void fillRange(@nullCheck int start, @nullCheck int end, [E? fillValue]) {
     checkMutable('fill range');
     RangeError.checkValidRange(start, end, this.length);
     E checkedFillValue = fillValue as E;
     for (int i = start; i < end; i++) {
       JS('', '#[#] = #', this, i, checkedFillValue);
     }
   }

   void replaceRange(
       @nullCheck int start, @nullCheck int end, Iterable<E> replacement) {
     checkGrowable('replace range');
     RangeError.checkValidRange(start, end, this.length);
     if (replacement is! EfficientLengthIterable) {
       replacement = replacement.toList();
     }
     int removeLength = end - start;
     @nullCheck
     int insertLength = replacement.length;
     if (removeLength >= insertLength) {
       int delta = removeLength - insertLength;
       int insertEnd = start + insertLength;
       int newLength = this.length - delta;
       this.setRange(start, insertEnd, replacement);
       if (delta != 0) {
         this.setRange(insertEnd, newLength, this, end);
         this.length = newLength;
       }
     } else {
       int delta = insertLength - removeLength;
       int newLength = this.length + delta;
       int insertEnd = start + insertLength; // aka. end + delta.
       this._setLengthUnsafe(newLength);
       this.setRange(insertEnd, newLength, this, end);
       this.setRange(start, insertEnd, replacement);
     }
   }

   bool any(bool Function(E) test) {
     int end = this.length;
     for (int i = 0; i < end; i++) {
       var element = JS<E>('', '#[#]', this, i);
       if (test(element)) return true;
       if (this.length != end) throw ConcurrentModificationError(this);
     }
     return false;
   }

   bool every(bool Function(E) test) {
     int end = this.length;
     for (int i = 0; i < end; i++) {
       var element = JS<E>('', '#[#]', this, i);
       if (!test(element)) return false;
       if (this.length != end) throw ConcurrentModificationError(this);
     }
     return true;
   }

   Iterable<E> get reversed => ReversedListIterable<E>(this);

   void sort([int Function(E, E)? compare]) {
     checkMutable('sort');
     if (compare == null) {
       Sort.sort(
           this, (a, b) => Comparable.compare(a as Comparable, b as Comparable));
     } else {
       Sort.sort(this, compare);
     }
   }

   void shuffle([Random? random]) {
     checkMutable('shuffle');
     if (random == null) random = Random();
     int length = this.length;
     while (length > 1) {
       int pos = random.nextInt(length);
       length -= 1;
       var tmp = this[length];
       this[length] = this[pos];
       this[pos] = tmp;
     }
   }

   int indexOf(Object? element, [@nullCheck int start = 0]) {
     int length = this.length;
     if (start >= length) {
       return -1;
     }
     if (start < 0) {
       start = 0;
     }
     for (int i = start; i < length; i++) {
       if (this[i] == element) {
         return i;
       }
     }
     return -1;
   }

   int lastIndexOf(Object? element, [int? startIndex]) {
     @notNull
     int start = startIndex ?? this.length - 1;
     if (start >= this.length) {
       start = this.length - 1;
     } else if (start < 0) {
       return -1;
     }
     for (int i = start; i >= 0; i--) {
       if (this[i] == element) {
         return i;
       }
     }
     return -1;
   }

   bool contains(Object? other) {
     var length = this.length;
     for (int i = 0; i < length; i++) {
       var element = JS<E>('', '#[#]', this, i);
       if (element == other) return true;
     }
     return false;
   }

   @notNull
   bool get isEmpty => length == 0;

   @notNull
   bool get isNotEmpty => !isEmpty;

   String toString() => ListBase.listToString(this);

   List<E> toList({@nullCheck bool growable = true}) {
     var list = JS('', '#.slice()', this);
     if (!growable) markFixedList(list);
     return JSArray<E>.of(list);
   }

   Set<E> toSet() => Set<E>.from(this);

   Iterator<E> get iterator => ArrayIterator<E>(this);

   int get hashCode => identityHashCode(this);

   @notNull
   bool operator ==(other) => identical(this, other);

   @notNull
   int get length => JS<int>('!', r'#.length', this);

   void set length(@nullCheck int newLength) {
     checkGrowable('set length');
     // TODO(sra): Remove this test and let JavaScript throw an error.
     if (newLength < 0) {
       throw RangeError.range(newLength, 0, null, 'newLength');
     }

     // Verify that element type is nullable.
     if (newLength > length) null as E;

     // JavaScript with throw a RangeError for numbers that are too big. The
     // message does not contain the value.
     JS('void', r'#.length = #', this, newLength);
   }

   /// Unsafe alternative to the [length] setter that skips the check and will
   /// not fail when increasing the size of a list of non-nullable elements.
   ///
   /// To ensure null safe soundness this should only be called when every new
   /// index will be filled before returning.
   ///
   /// Should only be called when the list is already known to be growable.
   void _setLengthUnsafe(int newLength) {
     // TODO(sra): Remove this test and let JavaScript throw an error.
     if (newLength < 0) {
       throw RangeError.range(newLength, 0, null, 'newLength');
     }
     // JavaScript with throw a RangeError for numbers that are too big. The
     // message does not contain the value.
     JS('void', r'#.length = #', this, newLength);
   }

   E operator [](int index) {
     // Suppress redundant null checks via JS.
     if (index == null ||
         JS<int>('!', '#', index) >= JS<int>('!', '#.length', this) ||
         JS<int>('!', '#', index) < 0) {
       throw diagnoseIndexError(this, index);
     }
     return JS<E>('', '#[#]', this, index);
   }

   void operator []=(int index, E value) {
     checkMutable('indexed set');
     if (index == null ||
         JS<int>('!', '#', index) >= JS<int>('!', '#.length', this) ||
         JS<int>('!', '#', index) < 0) {
       throw diagnoseIndexError(this, index);
     }
     JS('void', r'#[#] = #', this, index, value);
   }

   Map<int, E> asMap() {
     return ListMapView<E>(this);
   }

   Type get runtimeType =>
       dart.wrapType(JS('', '#(#)', dart.getGenericClass(List), E));

   Iterable<E> followedBy(Iterable<E> other) =>
       FollowedByIterable<E>.firstEfficient(this, other);

   Iterable<T> whereType<T>() => new WhereTypeIterable<T>(this);

   List<E> operator +(List<E> other) => [...this, ...other];

   int indexWhere(bool Function(E) test, [int start = 0]) {
     if (start >= this.length) return -1;
     if (start < 0) start = 0;
     for (int i = start; i < this.length; i++) {
       if (test(this[i])) return i;
     }
     return -1;
   }

   int lastIndexWhere(bool Function(E) test, [int? start]) {
     if (start == null) start = this.length - 1;
     if (start < 0) return -1;
     for (int i = start; i >= 0; i--) {
       if (test(this[i])) return i;
     }
     return -1;
   }

   void set first(E element) {
     if (this.isEmpty) throw RangeError.index(0, this);
     this[0] = element;
   }

   void set last(E element) {
     if (this.isEmpty) throw RangeError.index(0, this);
     this[this.length - 1] = element;
   }
 }

 /**
  * Dummy subclasses that allow the backend to track more precise
  * information about arrays through their type. The CPA type inference
  * relies on the fact that these classes do not override [] nor []=.
  *
  * These classes are really a fiction, and can have no methods, since
  * getInterceptor always returns JSArray.  We should consider pushing the
  * 'isGrowable' and 'isMutable' checks into the getInterceptor implementation so
  * these classes can have specialized implementations. Doing so will challenge
  * many assumptions in the JS backend.
  */
 class JSMutableArray<E> extends JSArray<E> implements JSMutableIndexable<E> {}

 class JSFixedArray<E> extends JSMutableArray<E> {}

 class JSExtendableArray<E> extends JSMutableArray<E> {}

 class JSUnmodifiableArray<E> extends JSArray<E> {} // Already is JSIndexable.

 /// An [Iterator] that iterates a JSArray.
 ///
 class ArrayIterator<E> implements Iterator<E> {
   final JSArray<E> _iterable;
   @notNull
   final int _length;
   @notNull
   int _index;
   E? _current;

   ArrayIterator(JSArray<E> iterable)
       : _iterable = iterable,
         _length = iterable.length,
         _index = 0;

   E get current => _current as E;

   bool moveNext() {
     @notNull
     int length = _iterable.length;

     // We have to do the length check even on fixed length Arrays.  If we can
     // inline moveNext() we might be able to GVN the length and eliminate this
     // check on known fixed length JSArray.
     if (_length != length) {
       throw throwConcurrentModificationError(_iterable);
     }

     if (_index >= length) {
       _current = null;
       return false;
     }
     _current = _iterable[_index];
     _index++;
     return true;
   }
 }
	// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file
	// for details. All rights reserved. Use of this source code is governed by a
	// BSD-style license that can be found in the LICENSE file.

	part of dart._interceptors;

	/**
	* The interceptor class for [List]. The compiler recognizes this
	* class as an interceptor, and changes references to [:this:] to
	* actually use the receiver of the method, which is generated as an extra
	* argument added to each member.
	*/
	@JsPeerInterface(name: 'Array')
	class JSArray<E> implements List<E>, JSIndexable<E> {
	const JSArray();

	/**
	* Constructor for adding type parameters to an existing JavaScript
	* Array. Used for creating literal lists.
	*/
	factory JSArray.of(list) {
	// TODO(sra): Move this to core.List for better readability.
	//
	// TODO(jmesserly): this uses special compiler magic to close over the
	// parameterized ES6 'JSArray' class.
	JS('', '#.__proto__ = JSArray.prototype', list);
	return JS('-dynamic', '#', list);
	}

	// TODO(jmesserly): consider a fixed array subclass instead.
	factory JSArray.fixed(list) {
	JS('', '#.__proto__ = JSArray.prototype', list);
	JS('', r'#.fixed$length = Array', list);
	return JS('-dynamic', '#', list);
	}

	factory JSArray.unmodifiable(list) {
	JS('', '#.__proto__ = JSArray.prototype', list);
	JS('', r'#.fixed$length = Array', list);
	JS('', r'#.immutable$list = Array', list);
	return JS('-dynamic', '#', list);
	}

	static void markFixedList(list) {
	// Functions are stored in the hidden class and not as properties in
	// the object. We never actually look at the value, but only want
	// to know if the property exists.
	JS('', r'#.fixed$length = Array', list);
	}

	static void markUnmodifiableList(list) {
	// Functions are stored in the hidden class and not as properties in
	// the object. We never actually look at the value, but only want
	// to know if the property exists.
	JS('', r'#.fixed$length = Array', list);
	JS('', r'#.immutable$list = Array', list);
	}

	checkMutable(reason) {
	if (JS<bool>('!', r'#.immutable$list', this)) {
	throw UnsupportedError(reason);
	}
	}

	checkGrowable(reason) {
	if (JS<bool>('!', r'#.fixed$length', this)) {
	throw UnsupportedError(reason);
	}
	}

	List<R> cast<R>() => List.castFrom<E, R>(this);
	void add(E value) {
	checkGrowable('add');
	JS('void', r'#.push(#)', this, value);
	}

	E removeAt(@nullCheck int index) {
	checkGrowable('removeAt');
	if (index < 0 \|\| index >= length) {
	throw RangeError.value(index);
	}
	return JS('-dynamic', r'#.splice(#, 1)[0]', this, index);
	}

	void insert(@nullCheck int index, E value) {
	checkGrowable('insert');
	if (index < 0 \|\| index > length) {
	throw RangeError.value(index);
	}
	JS('void', r'#.splice(#, 0, #)', this, index, value);
	}

	void insertAll(@nullCheck int index, Iterable<E> iterable) {
	checkGrowable('insertAll');
	RangeError.checkValueInInterval(index, 0, this.length, "index");
	if (iterable is! EfficientLengthIterable) {
	iterable = iterable.toList();
	}
	@nullCheck
	int insertionLength = iterable.length;
	this._setLengthUnsafe(this.length + insertionLength);
	int end = index + insertionLength;
	this.setRange(end, this.length, this, index);
	this.setRange(index, end, iterable);
	}

	void setAll(@nullCheck int index, Iterable<E> iterable) {
	checkMutable('setAll');
	RangeError.checkValueInInterval(index, 0, this.length, "index");
	for (var element in iterable) {
	this[index++] = element;
	}
	}

	E removeLast() {
	checkGrowable('removeLast');
	if (length == 0) throw diagnoseIndexError(this, -1);
	return JS('var', r'#.pop()', this);
	}

	bool remove(Object? element) {
	checkGrowable('remove');
	var length = this.length;
	for (int i = 0; i < length; i++) {
	if (this[i] == element) {
	JS('var', r'#.splice(#, 1)', this, i);
	return true;
	}
	}
	return false;
	}

	/**
	* Removes elements matching [test] from [this] List.
	*/
	void removeWhere(bool Function(E) test) {
	checkGrowable('removeWhere');
	_removeWhere(test, true);
	}

	void retainWhere(bool Function(E) test) {
	checkGrowable('retainWhere');
	_removeWhere(test, false);
	}

	void _removeWhere(bool Function(E) test, bool removeMatching) {
	// Performed in two steps, to avoid exposing an inconsistent state
	// to the [test] function. First the elements to retain are found, and then
	// the original list is updated to contain those elements.

	// TODO(sra): Replace this algorithm with one that retains a list of ranges
	// to be removed. Most real uses remove 0, 1 or a few clustered elements.

	List retained = [];
	int end = this.length;
	for (int i = 0; i < end; i++) {
	var element = JS<E>('', '#[#]', this, i);
	// !test() ensures bool conversion in checked mode.
	if (!test(element) == removeMatching) {
	// Unsafe add here to avoid extra casts and growable checks enforced by
	// the exposed add method.
	JS('', '#.push(#)', retained, element);
	}
	if (this.length != end) throw ConcurrentModificationError(this);
	}
	if (retained.length == end) return;
	this.length = retained.length;
	@nullCheck
	var length = retained.length;
	for (int i = 0; i < length; i++) {
	JS('', '#[#] = #[#]', this, i, retained, i);
	}
	}

	Iterable<E> where(bool Function(E) f) {
	return WhereIterable<E>(this, f);
	}

	Iterable<T> expand<T>(Iterable<T> Function(E) f) {
	return ExpandIterable<E, T>(this, f);
	}

	void addAll(Iterable<E> collection) {
	int i = this.length;
	checkGrowable('addAll');
	for (E e in collection) {
	assert(i == this.length \|\| (throw ConcurrentModificationError(this)));
	i++;
	JS('void', r'#.push(#)', this, e);
	}
	}

	void clear() {
	length = 0;
	}

	void forEach(void Function(E) f) {
	int end = this.length;
	for (int i = 0; i < end; i++) {
	var element = JS<E>('', '#[#]', this, i);
	f(element);
	if (this.length != end) throw ConcurrentModificationError(this);
	}
	}

	Iterable<T> map<T>(T Function(E) f) {
	return MappedListIterable<E, T>(this, f);
	}

	String join([String separator = ""]) {
	var length = this.length;
	var list = List<String>.filled(length, "");
	for (int i = 0; i < length; i++) {
	list[i] = "${this[i]}";
	}
	return JS<String>('!', "#.join(#)", list, separator);
	}

	Iterable<E> take(int n) {
	return SubListIterable<E>(this, 0, n);
	}

	Iterable<E> takeWhile(bool test(E value)) {
	return TakeWhileIterable<E>(this, test);
	}

	Iterable<E> skip(int n) {
	return SubListIterable<E>(this, n, null);
	}

	Iterable<E> skipWhile(bool Function(E) test) {
	return SkipWhileIterable<E>(this, test);
	}

	E reduce(E combine(E previousValue, E element)) {
	int length = this.length;
	if (length == 0) throw IterableElementError.noElement();
	E value = this[0];
	for (int i = 1; i < length; i++) {
	var element = JS<E>('', '#[#]', this, i);
	value = combine(value, element);
	if (length != this.length) throw ConcurrentModificationError(this);
	}
	return value;
	}

	T fold<T>(T initialValue, T Function(T previousValue, E element) combine) {
	var value = initialValue;
	int length = this.length;
	for (int i = 0; i < length; i++) {
	var element = JS<E>('', '#[#]', this, i);
	value = combine(value, element);
	if (this.length != length) throw ConcurrentModificationError(this);
	}
	return value;
	}

	E firstWhere(bool Function(E) test, {E Function()? orElse}) {
	int end = this.length;
	for (int i = 0; i < end; ++i) {
	var element = JS<E>('', '#[#]', this, i);
	if (test(element)) return element;
	if (this.length != end) throw ConcurrentModificationError(this);
	}
	if (orElse != null) return orElse();
	throw IterableElementError.noElement();
	}

	E lastWhere(bool Function(E) test, {E Function()? orElse}) {
	int length = this.length;
	for (int i = length - 1; i >= 0; i--) {
	var element = JS<E>('', '#[#]', this, i);
	if (test(element)) return element;
	if (length != this.length) {
	throw ConcurrentModificationError(this);
	}
	}
	if (orElse != null) return orElse();
	throw IterableElementError.noElement();
	}

	E singleWhere(bool Function(E) test, {E Function()? orElse}) {
	int length = this.length;
	E? match = null;
	bool matchFound = false;
	for (int i = 0; i < length; i++) {
	var element = JS<E>('', '#[#]', this, i);
	if (test(element)) {
	if (matchFound) {
	throw IterableElementError.tooMany();
	}
	matchFound = true;
	match = element;
	}
	if (length != this.length) {
	throw ConcurrentModificationError(this);
	}
	}
	if (matchFound) return match as E;
	if (orElse != null) return orElse();
	throw IterableElementError.noElement();
	}

	E elementAt(int index) {
	return this[index];
	}

	List<E> sublist(@nullCheck int start, [int? end]) {
	if (start < 0 \|\| start > length) {
	throw RangeError.range(start, 0, length, "start");
	}
	if (end == null) {
	end = length;
	} else {
	@notNull
	var _end = end;
	if (_end < start \|\| _end > length) {
	throw RangeError.range(end, start, length, "end");
	}
	}
	if (start == end) return <E>[];
	return JSArray<E>.of(JS('', r'#.slice(#, #)', this, start, end));
	}

	Iterable<E> getRange(int start, int end) {
	RangeError.checkValidRange(start, end, this.length);
	return SubListIterable<E>(this, start, end);
	}

	E get first {
	if (length > 0) return this[0];
	throw IterableElementError.noElement();
	}

	E get last {
	if (length > 0) return this[length - 1];
	throw IterableElementError.noElement();
	}

	E get single {
	if (length == 1) return this[0];
	if (length == 0) throw IterableElementError.noElement();
	throw IterableElementError.tooMany();
	}

	void removeRange(@nullCheck int start, @nullCheck int end) {
	checkGrowable('removeRange');
	RangeError.checkValidRange(start, end, this.length);
	int deleteCount = end - start;
	JS('', '#.splice(#, #)', this, start, deleteCount);
	}

	void setRange(@nullCheck int start, @nullCheck int end, Iterable<E> iterable,
	[@nullCheck int skipCount = 0]) {
	checkMutable('set range');

	RangeError.checkValidRange(start, end, this.length);
	int length = end - start;
	if (length == 0) return;
	RangeError.checkNotNegative(skipCount, "skipCount");

	var otherList = <E>[];
	int otherStart = 0;
	// TODO(floitsch): Make this accept more.
	if (iterable is List<E>) {
	otherList = iterable;
	otherStart = skipCount;
	} else {
	otherList = iterable.skip(skipCount).toList(growable: false);
	otherStart = 0;
	}
	if (otherStart + length > otherList.length) {
	throw IterableElementError.tooFew();
	}
	if (otherStart < start) {
	// Copy backwards to ensure correct copy if [from] is this.
	// TODO(sra): If [from] is the same Array as [this], we can copy without
	// type annotation checks on the stores.
	for (int i = length - 1; i >= 0; i--) {
	// Use JS to avoid bounds check (the bounds check elimination
	// optimzation is too weak). The 'E' type annotation is a store type
	// check - we can't rely on iterable, it could be List<dynamic>.
	var element = otherList[otherStart + i];
	JS('', '#[#] = #', this, start + i, element);
	}
	} else {
	for (int i = 0; i < length; i++) {
	var element = otherList[otherStart + i];
	JS('', '#[#] = #', this, start + i, element);
	}
	}
	}

	void fillRange(@nullCheck int start, @nullCheck int end, [E? fillValue]) {
	checkMutable('fill range');
	RangeError.checkValidRange(start, end, this.length);
	E checkedFillValue = fillValue as E;
	for (int i = start; i < end; i++) {
	JS('', '#[#] = #', this, i, checkedFillValue);
	}
	}

	void replaceRange(
	@nullCheck int start, @nullCheck int end, Iterable<E> replacement) {
	checkGrowable('replace range');
	RangeError.checkValidRange(start, end, this.length);
	if (replacement is! EfficientLengthIterable) {
	replacement = replacement.toList();
	}
	int removeLength = end - start;
	@nullCheck
	int insertLength = replacement.length;
	if (removeLength >= insertLength) {
	int delta = removeLength - insertLength;
	int insertEnd = start + insertLength;
	int newLength = this.length - delta;
	this.setRange(start, insertEnd, replacement);
	if (delta != 0) {
	this.setRange(insertEnd, newLength, this, end);
	this.length = newLength;
	}
	} else {
	int delta = insertLength - removeLength;
	int newLength = this.length + delta;
	int insertEnd = start + insertLength; // aka. end + delta.
	this._setLengthUnsafe(newLength);
	this.setRange(insertEnd, newLength, this, end);
	this.setRange(start, insertEnd, replacement);
	}
	}

	bool any(bool Function(E) test) {
	int end = this.length;
	for (int i = 0; i < end; i++) {
	var element = JS<E>('', '#[#]', this, i);
	if (test(element)) return true;
	if (this.length != end) throw ConcurrentModificationError(this);
	}
	return false;
	}

	bool every(bool Function(E) test) {
	int end = this.length;
	for (int i = 0; i < end; i++) {
	var element = JS<E>('', '#[#]', this, i);
	if (!test(element)) return false;
	if (this.length != end) throw ConcurrentModificationError(this);
	}
	return true;
	}

	Iterable<E> get reversed => ReversedListIterable<E>(this);

	void sort([int Function(E, E)? compare]) {
	checkMutable('sort');
	if (compare == null) {
	Sort.sort(
	this, (a, b) => Comparable.compare(a as Comparable, b as Comparable));
	} else {
	Sort.sort(this, compare);
	}
	}

	void shuffle([Random? random]) {
	checkMutable('shuffle');
	if (random == null) random = Random();
	int length = this.length;
	while (length > 1) {
	int pos = random.nextInt(length);
	length -= 1;
	var tmp = this[length];
	this[length] = this[pos];
	this[pos] = tmp;
	}
	}

	int indexOf(Object? element, [@nullCheck int start = 0]) {
	int length = this.length;
	if (start >= length) {
	return -1;
	}
	if (start < 0) {
	start = 0;
	}
	for (int i = start; i < length; i++) {
	if (this[i] == element) {
	return i;
	}
	}
	return -1;
	}

	int lastIndexOf(Object? element, [int? startIndex]) {
	@notNull
	int start = startIndex ?? this.length - 1;
	if (start >= this.length) {
	start = this.length - 1;
	} else if (start < 0) {
	return -1;
	}
	for (int i = start; i >= 0; i--) {
	if (this[i] == element) {
	return i;
	}
	}
	return -1;
	}

	bool contains(Object? other) {
	var length = this.length;
	for (int i = 0; i < length; i++) {
	var element = JS<E>('', '#[#]', this, i);
	if (element == other) return true;
	}
	return false;
	}

	@notNull
	bool get isEmpty => length == 0;

	@notNull
	bool get isNotEmpty => !isEmpty;

	String toString() => ListBase.listToString(this);

	List<E> toList({@nullCheck bool growable = true}) {
	var list = JS('', '#.slice()', this);
	if (!growable) markFixedList(list);
	return JSArray<E>.of(list);
	}

	Set<E> toSet() => Set<E>.from(this);

	Iterator<E> get iterator => ArrayIterator<E>(this);

	int get hashCode => identityHashCode(this);

	@notNull
	bool operator ==(other) => identical(this, other);

	@notNull
	int get length => JS<int>('!', r'#.length', this);

	void set length(@nullCheck int newLength) {
	checkGrowable('set length');
	// TODO(sra): Remove this test and let JavaScript throw an error.
	if (newLength < 0) {
	throw RangeError.range(newLength, 0, null, 'newLength');
	}

	// Verify that element type is nullable.
	if (newLength > length) null as E;

	// JavaScript with throw a RangeError for numbers that are too big. The
	// message does not contain the value.
	JS('void', r'#.length = #', this, newLength);
	}

	/// Unsafe alternative to the [length] setter that skips the check and will
	/// not fail when increasing the size of a list of non-nullable elements.
	///
	/// To ensure null safe soundness this should only be called when every new
	/// index will be filled before returning.
	///
	/// Should only be called when the list is already known to be growable.
	void _setLengthUnsafe(int newLength) {
	// TODO(sra): Remove this test and let JavaScript throw an error.
	if (newLength < 0) {
	throw RangeError.range(newLength, 0, null, 'newLength');
	}
	// JavaScript with throw a RangeError for numbers that are too big. The
	// message does not contain the value.
	JS('void', r'#.length = #', this, newLength);
	}

	E operator [](int index) {
	// Suppress redundant null checks via JS.
	if (index == null \|\|
	JS<int>('!', '#', index) >= JS<int>('!', '#.length', this) \|\|
	JS<int>('!', '#', index) < 0) {
	throw diagnoseIndexError(this, index);
	}
	return JS<E>('', '#[#]', this, index);
	}

	void operator []=(int index, E value) {
	checkMutable('indexed set');
	if (index == null \|\|
	JS<int>('!', '#', index) >= JS<int>('!', '#.length', this) \|\|
	JS<int>('!', '#', index) < 0) {
	throw diagnoseIndexError(this, index);
	}
	JS('void', r'#[#] = #', this, index, value);
	}

	Map<int, E> asMap() {
	return ListMapView<E>(this);
	}

	Type get runtimeType =>
	dart.wrapType(JS('', '#(#)', dart.getGenericClass(List), E));

	Iterable<E> followedBy(Iterable<E> other) =>
	FollowedByIterable<E>.firstEfficient(this, other);

	Iterable<T> whereType<T>() => new WhereTypeIterable<T>(this);

	List<E> operator +(List<E> other) => [...this, ...other];

	int indexWhere(bool Function(E) test, [int start = 0]) {
	if (start >= this.length) return -1;
	if (start < 0) start = 0;
	for (int i = start; i < this.length; i++) {
	if (test(this[i])) return i;
	}
	return -1;
	}

	int lastIndexWhere(bool Function(E) test, [int? start]) {
	if (start == null) start = this.length - 1;
	if (start < 0) return -1;
	for (int i = start; i >= 0; i--) {
	if (test(this[i])) return i;
	}
	return -1;
	}

	void set first(E element) {
	if (this.isEmpty) throw RangeError.index(0, this);
	this[0] = element;
	}

	void set last(E element) {
	if (this.isEmpty) throw RangeError.index(0, this);
	this[this.length - 1] = element;
	}
	}

	/**
	* Dummy subclasses that allow the backend to track more precise
	* information about arrays through their type. The CPA type inference
	* relies on the fact that these classes do not override [] nor []=.
	*
	* These classes are really a fiction, and can have no methods, since
	* getInterceptor always returns JSArray. We should consider pushing the
	* 'isGrowable' and 'isMutable' checks into the getInterceptor implementation so
	* these classes can have specialized implementations. Doing so will challenge
	* many assumptions in the JS backend.
	*/
	class JSMutableArray<E> extends JSArray<E> implements JSMutableIndexable<E> {}

	class JSFixedArray<E> extends JSMutableArray<E> {}

	class JSExtendableArray<E> extends JSMutableArray<E> {}

	class JSUnmodifiableArray<E> extends JSArray<E> {} // Already is JSIndexable.

	/// An [Iterator] that iterates a JSArray.
	///
	class ArrayIterator<E> implements Iterator<E> {
	final JSArray<E> _iterable;
	@notNull
	final int _length;
	@notNull
	int _index;
	E? _current;

	ArrayIterator(JSArray<E> iterable)
	: _iterable = iterable,
	_length = iterable.length,
	_index = 0;

	E get current => _current as E;

	bool moveNext() {
	@notNull
	int length = _iterable.length;

	// We have to do the length check even on fixed length Arrays. If we can
	// inline moveNext() we might be able to GVN the length and eliminate this
	// check on known fixed length JSArray.
	if (_length != length) {
	throw throwConcurrentModificationError(_iterable);
	}

	if (_index >= length) {
	_current = null;
	return false;
	}
	_current = _iterable[_index];
	_index++;
	return true;
	}
	}