Revert "Add "contains" method to Collection."

lib/core/sequences.dart

-// 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.
-
-/**
- * An indexed sequence of elements of the same type.
- *
- * This is a primitive interface that any finite integer-indexable
- * sequence can implement.
- * It is intended for data structures where access by index is
- * the most efficient way to access the data.
- */
-abstract class Sequence<T> {
-  /**
-   * The limit of valid indices of the sequence.
-   *
-   * The length getter should be efficient.
-   */
-  int get length;
-
-  /**
-   * Returns the value at the given [index].
-   *
-   * Valid indices must be in the range [:0..length - 1:].
-   * The lookup operator should be efficient.
-   */
-  T operator[](int index);
-}
-
-/**
- * A skeleton class for a [Collection] that is also a [Sequence].
- */
-abstract class SequenceCollection<E> implements Collection<E>, Sequence<E> {
-  // The class is intended for use as a mixin as well.
-
-  Iterator<E> iterator() => new SequenceIterator(sequence);
-
-  void forEach(f(E element)) {
-    for (int i = 0; i < this.length; i++) f(this[i]);
-  }
-
-  Collection map(f(E element)) {
-    List result = new List();
-    for (int i = 0; i < this.length; i++) {
-      result.add(f(this[i]));
-    }
-    return result;
-  }
-
-  bool contains(E value) {
-    for (int i = 0; i < sequence.length; i++) {
-      if (sequence[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;
-  }
-
-  Collection<E> filter(bool f(E element)) {
-    List<E> result = <E>[];
-    for (int i = 0; i < this.length; i++) {
-      E element = this[i];
-      if (f(element)) result.add(element);
-    }
-    return result;
-  }
-
-  bool every(bool f(E element)) {
-    for (int i = 0; i < this.length; i++) {
-      if (!f(this[i])) return false;
-    }
-    return true;
-  }
-
-  bool some(bool f(E element)) {
-    for (int i = 0; i < this.length; i++) {
-      if (f(this[i])) return true;
-    }
-    return false;
-  }
-
-  bool isEmpty() {
-    return this.length == 0;
-  }
-}
-
-
-/**
- * An unmodifiable [List] backed by a [Sequence].
- */
-class SequenceList<E> extends SequenceCollection<E> implements List<E> {
-  Sequence<E> sequence;
-  SequenceList(this.sequence);
-
-  int get length => sequence.length;
-
-  T operator[](int index) => sequence[index];
-
-  int indexOf(E value, [int start = 0]) {
-    for (int i = start; i < sequence.length; i++) {
-      if (sequence[i] == value) return i;
-    }
-    return -1;
-  }
-
-  int lastIndexOf(E value, [int start]) {
-    if (start == null) start = sequence.length - 1;
-    for (int i = start; i >= 0; i--) {
-      if (sequence[i] == value) return i;
-    }
-    return -1;
-  }
-
-  E last() => sequence[sequence.length - 1];
-
-  List<E> getRange(int start, int length) {
-    List<E> result = <E>[];
-    for (int i = 0; i < length; i++) {
-      result.add(sequence[start + i]);
-    }
-    return result;
-  }
-
-  void operator []=(int index, E value) {
-    throw new UnsupportedOperationException(
-        "Cannot modify an unmodifiable list");
-  }
-
-  void set length(int newLength) {
-    throw new UnsupportedOperationException(
-        "Cannot change the length of an unmodifiable list");
-  }
-
-  void add(E value) {
-    throw new UnsupportedOperationException(
-        "Cannot add to an unmodifiable list");
-  }
-
-  void addLast(E value) {
-    throw new UnsupportedOperationException(
-        "Cannot add to an unmodifiable list");
-  }
-
-  void addAll(Collection<E> collection) {
-    throw new UnsupportedOperationException(
-        "Cannot add to an unmodifiable list");
-  }
-
-  void sort([Comparator<E> compare]) {
-    throw new UnsupportedOperationException(
-        "Cannot modify an unmodifiable list");
-  }
-
-  void clear() {
-    throw new UnsupportedOperationException(
-        "Cannot clear an unmodifiable list");
-  }
-
-  E removeAt(int index) {
-    throw new UnsupportedOperationException(
-        "Cannot remove in an unmodifiable list");
-  }
-
-  E removeLast() {
-    throw new UnsupportedOperationException(
-        "Cannot remove in an unmodifiable list");
-  }
-
-  void setRange(int start, int length, List<E> from, [int startFrom]) {
-    throw new UnsupportedOperationException(
-        "Cannot modify an unmodifiable list");
-  }
-
-  void removeRange(int start, int length) {
-    throw new UnsupportedOperationException(
-        "Cannot remove in an unmodifiable list");
-  }
-
-  void insertRange(int start, int length, [E initialValue]) {
-    throw new UnsupportedOperationException(
-        "Cannot insert range in an unmodifiable list");
-  }
-}
-
-/**
- * Iterates over a [Sequence] in growing index order.
- */
-class SequenceIterator<E> implements Iterator<E> {
-  Sequence<E> _sequence;
-  int _position;
-  SequenceIterator(this._sequence) : _position = 0;
-  bool hasNext() => _position < _sequence.length;
-  E next() {
-    if (hasNext()) return _sequence[_position++];
-    throw new NoMoreElementsException();
-  }
-}
-