Move list helper-classes from core to collection-dev.

sdk/lib/collection_dev/list.dart

+// Copyright (c) 2013, 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.collection.dev;
+
+/**
+ * Skeleton class for an unmodifiable [List].

[floitsch, 2013/01/17 18:31:47]

Changed this comment. Otherwise identical to old code.

+ */
+abstract class NonExtensibleListMixin<E>
+    extends Iterable<E> implements List<E> {
+
+  Iterator<E> get iterator => new ListIterator(this);
+
+  void forEach(f(E element)) {
+    for (int i = 0; i < this.length; i++) f(this[i]);
+  }
+
+  bool contains(E value) {
+    for (int i = 0; i < length; i++) {
+      if (this[i] == value) return true;
+    }
+    return false;
+  }
+
+  reduce(initialValue, combine(previousValue, E element)) {
+    var value = initialValue;
+    for (int i = 0; i < this.length; i++) {
+      value = combine(value, this[i]);
+    }
+    return value;
+  }
+
+  bool every(bool f(E element)) {
+    for (int i = 0; i < this.length; i++) {
+      if (!f(this[i])) return false;
+    }
+    return true;
+  }
+
+  bool any(bool f(E element)) {
+    for (int i = 0; i < this.length; i++) {
+      if (f(this[i])) return true;
+    }
+    return false;
+  }
+
+  bool get isEmpty {
+    return this.length == 0;
+  }
+
+  E elementAt(int index) {
+    return this[index];
+  }
+
+  int indexOf(E value, [int start = 0]) {
+    for (int i = start; i < length; i++) {
+      if (this[i] == value) return i;
+    }
+    return -1;
+  }
+
+  int lastIndexOf(E value, [int start]) {
+    if (start == null) start = length - 1;
+    for (int i = start; i >= 0; i--) {
+      if (this[i] == value) return i;
+    }
+    return -1;
+  }
+
+  E get first {
+    if (length > 0) return this[0];
+    throw new StateError("No elements");
+  }
+
+  E get last {
+    if (length > 0) return this[length - 1];
+    throw new StateError("No elements");
+  }
+
+  E get single {
+    if (length == 1) return this[0];
+    if (length == 0) throw new StateError("No elements");
+    throw new StateError("More than one element");
+  }
+
+  List<E> getRange(int start, int length) {
+    List<E> result = <E>[];
+    for (int i = 0; i < length; i++) {
+      result.add(this[start + i]);
+    }
+    return result;
+  }
+
+  void operator []=(int index, E value) {
+    throw new UnsupportedError(
+        "Cannot modify an unmodifiable list");
+  }
+
+  void set length(int newLength) {
+    throw new UnsupportedError(
+        "Cannot change the length of an unmodifiable list");
+  }
+
+  void add(E value) {
+    throw new UnsupportedError(
+        "Cannot add to an unmodifiable list");
+  }
+
+  void addLast(E value) {
+    throw new UnsupportedError(
+        "Cannot add to an unmodifiable list");
+  }
+
+  void addAll(Iterable<E> iterable) {
+    throw new UnsupportedError(
+        "Cannot add to an unmodifiable list");
+  }
+
+  void sort([Comparator<E> compare]) {
+    throw new UnsupportedError(
+        "Cannot modify an unmodifiable list");
+  }
+
+  void clear() {
+    throw new UnsupportedError(
+        "Cannot clear an unmodifiable list");
+  }
+
+  E removeAt(int index) {
+    throw new UnsupportedError(
+        "Cannot remove in an unmodifiable list");
+  }
+
+  E removeLast() {
+    throw new UnsupportedError(
+        "Cannot remove in an unmodifiable list");
+  }
+
+  void setRange(int start, int length, List<E> from, [int startFrom]) {
+    throw new UnsupportedError(
+        "Cannot modify an unmodifiable list");
+  }
+
+  void removeRange(int start, int length) {
+    throw new UnsupportedError(
+        "Cannot remove in an unmodifiable list");
+  }
+
+  void insertRange(int start, int length, [E initialValue]) {
+    throw new UnsupportedError(
+        "Cannot insert range in an unmodifiable list");
+  }
+}
+
+/**
+ * Iterates over a [Sequence] in growing index order.

[Lasse Reichstein Nielsen, 2013/01/18 11:34:25]

Sequence -> List.

[floitsch, 2013/01/18 17:02:29]

Done.

+ */
+class ListIterator<E> implements Iterator<E> {
+  final List<E> _list;
+  int _position;
+  E _current;
+
+  ListIterator(this._list) : _position = -1;
+
+  bool moveNext() {
+    int nextPosition = _position + 1;
+    if (nextPosition < _list.length) {
+      _current = _list[nextPosition];
+      _position = nextPosition;
+      return true;
+    }
+    _position = _list.length;
+    _current = null;
+    return false;
+  }
+
+  E get current => _current;
+}
+
+class MappedList<S, T> extends NonExtensibleListMixin<T> {
+  final List<S> _list;
+  // TODO(ahe): Restore type when feature is implemented in dart2js
+  // checked mode. http://dartbug.com/7733
+  final /* _Transformation<S, T> */ _f;
+
+  MappedList(this._list, T this._f(S element));
+
+  T operator[](int index) => _f(_list[index]);
+  int get length => _list.length;
+}
+
+/**
+ * An immutable view of a [List].
+ */
+class ListView<E> extends NonExtensibleListMixin<E> {
+  final List<E> _list;
+  final int _offset;
+  final int _length;
+
+  /**
+   * If the given length is `null` then the ListView's length is bound by
+   * the backed [list].
+   */
+  ListView(List<E> list, this._offset, this._length) : _list = list {
+    if (_offset is! int || _offset < 0) {
+      throw new ArgumentError(_offset);
+    }
+    if (_length != null &&
+        (_length is! int || _length < 0)) {
+      throw new ArgumentError(_length);
+    }
+  }
+
+  int get length {
+    int originalLength = _list.length;
+    int skipLength = originalLength - _offset;
+    if (skipLength < 0) return 0;
+    if (_length == null || _length > skipLength) return skipLength;
+    return _length;
+  }
+
+  E operator[](int index) {
+    int skipIndex = index + _offset;
+    if (index < 0 ||
+        (_length != null && index >= _length) ||
+        index + _offset >= _list.length) {
+      throw new RangeError.value(index);
+    }
+    return _list[index + _offset];
+  }
+
+  ListView<E> skip(int skipCount) {
+    if (skipCount is! int || skipCount < 0) {
+      throw new ArgumentError(skipCount);
+    }
+    return new ListView(_list, _offset + skipCount, _length);
+  }
+
+  ListView<E> take(int takeCount) {
+    if (takeCount is! int || takeCount < 0) {
+      throw new ArgumentError(takeCount);
+    }
+    int newLength = takeCount;
+    if (_length != null && takeCount > _length) newLength = _length;
+    return new ListView(_list, _offset, newLength);
+  }
+}