Added examples to list.dart.

sdk/lib/core/list.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.
 
 part of dart.core;
 
 /**
  * An indexable collection of objects with a length.
  *
  * Subclasses of this class implement different kinds of lists.
  * The most common kinds of lists are:
  *
  * * Fixed-length list.
  *   An error occurs when attempting to use operations
  *   that can change the length of the list.
  *
  * * Growable list. Full implementation of the API defined in this class.
  *
  * The following code illustrates that some List implementations support
  * only a subset of the API.
  *
- *     var fixedLengthList = new List(5);
- *     fixedLengthList.length = 0;  // Error.
- *     fixedLengthList.add(499);    // Error.
+ *     List<int> fixedLengthList = new List(5);
+ *     fixedLengthList.length = 0;  // Error
+ *     fixedLengthList.add(499);    // Error
  *     fixedLengthList[0] = 87;
- *
- *     var growableList = [1, 2];
+ *     List<int> growableList = [1, 2];
  *     growableList.length = 0;
  *     growableList.add(499);
  *     growableList[0] = 87;
  *
- * Lists are [Iterable].
- * Iteration occurs over values in index order.
- * Changing the values does not affect iteration,
- * but changing the valid indices&mdash;that is,
- * changing the list's length&mdash;between
- * iteration steps
- * causes a [ConcurrentModificationError].
- * This means that only growable lists can throw ConcurrentModificationError.
- * If the length changes temporarily
- * and is restored before continuing the iteration,
- * the iterator does not detect it.
+ * Lists are [Iterable]. Iteration occurs over values in index order. Changing
+ * the values does not affect iteration, but changing the valid
+ * indices&mdash;that is, changing the list's length&mdash;between iteration
+ * steps causes a [ConcurrentModificationError]. This means that only growable
+ * lists can throw ConcurrentModificationError. If the length changes
+ * temporarily and is restored before continuing the iteration, the iterator
+ * does not detect it.
  */
 abstract class List<E> implements Iterable<E> {
   /**
-   * Creates a list of the given _length_.
+   * Creates a list of the given length.
    *
-   * The created list is fixed-length if _length_ is provided.
-   * The list has length 0 and is growable if _length_ is omitted.
+   * The created list is fixed-length if [length] is provided.
    *
-   * An error occurs if _length_ is negative.
+   *     List fixedLengthList = new List(3);
+   *     fixedLengthList.length;     // 3
+         fixedLengthList.length = 1; // Error
+   *
+   *
+   * The list has length 0 and is growable if [length] is omitted.
+   *
+   *     List growableList = new List();
+   *     growableList.length; // 0;
+   *     growableList.length = 3;
+   *
+   * An error occurs if [length] is negative.
    */
   external factory List([int length]);
 
   /**
-   * Creates a fixed-length list of the given _length_
-   * and initializes the value at each position with [fill].
+   * Creates a fixed-length list of the given length, and initializes the
+   * value at each position with [fill]:
+   *
+   *     new List<int>.filled(3, 0); // [0, 0, 0]
    */
   external factory List.filled(int length, E fill);
 
   /**
    * Creates a list and initializes it using the contents of [other].
    *
    * The [Iterator] of [other] provides the order of the objects.
    *
    * This constructor returns a growable list if [growable] is true;
    * otherwise, it returns a fixed-length list.
    */
   factory List.from(Iterable other, { bool growable: true }) {
     List<E> list = new List<E>();
     for (E e in other) {
       list.add(e);
     }
     if (growable) return list;
     int length = list.length;
     List<E> fixedList = new List<E>(length);
     for (int i = 0; i < length; i++) {
       fixedList[i] = list[i];
     }
     return fixedList;
   }
 
   /**
    * Generates a list of values.
    *
-   * Creates a list with _length_ positions
-   * and fills it with values created by calling [generator]
-   * for each index in the range `0` .. `length - 1`
+   * Creates a list with [length] positions and fills it with values created by
+   * calling [generator] for each index in the range `0` .. `length - 1`
    * in increasing order.
    *
+   *     new List<int>.generate(3, (int index) => index * index); // [0, 1, 4]
+   *
    * The created list is fixed-length unless [growable] is true.
    */
   factory List.generate(int length, E generator(int index),
                        { bool growable: true }) {
     List<E> result;
     if (growable) {
       result = <E>[]..length = length;
     } else {
       result = new List<E>(length);
     }
@@ skipping 19 matching lines @@
    * Returns the number of objects in this list.
    *
    * The valid indices for a list are `0` through `length - 1`.
    */
   int get length;
 
   /**
    * Changes the length of this list.
    *
    * If [newLength] is greater than
-   * the current [length], entries are initialized to [:null:].
+   * the current length, entries are initialized to [:null:].
    *
    * Throws an [UnsupportedError] if the list is fixed-length.
    */
   void set length(int newLength);
 
   /**
    * Adds [value] to the end of this list,
    * extending the length by one.
    *
    * Throws an [UnsupportedError] if the list is fixed-length.
@@ skipping 10 matching lines @@
 
   /**
    * Returns an [Iterable] of the objects in this list in reverse order.
    */
   Iterable<E> get reversed;
 
   /**
    * Sorts this list according to the order specified by the [compare] function.
    *
    * The [compare] function must act as a [Comparator].
+
+   *     List<String> numbers = ['one', 'two', 'three', 'four'];
+   *     // Sort from shortest to longest.
+   *     numbers.sort((x, y) => x.length.compareTo(y.length));
+   *     numbers.join(', '); // 'one, two, four, three'
    *
    * The default List implementations use [Comparable.compare] if
    * [compare] is omitted.
+   *
+   *     List<int> nums = [13, 2, -11];
+   *     nums.sort();
+         nums.join(', '); // '-11, 2, 13'
    */
   void sort([int compare(E a, E b)]);
 
   /**
    * Returns the first index of [element] in this list.
    *
-   * Searches the list from index [start] to the length of the list.
+   * Searches the list from index [start] to the end of the list.
    * The first time an object [:o:] is encountered so that [:o == element:],
    * the index of [:o:] is returned.
+   *
+   *     List<String> notes = ['do', 're', 'mi', 're'];
+   *     notes.indexOf('re');    // 1
+   *     notes.indexOf('re', 2); // 3
+   *
    * Returns -1 if [element] is not found.
+   *
+   *     notes.indexOf('fa');    // -1
    */
   int indexOf(E element, [int start = 0]);
 
   /**
    * Returns the last index of [element] in this list.
    *
    * Searches the list backwards from index [start] to 0.
    *
    * The first time an object [:o:] is encountered so that [:o == element:],
    * the index of [:o:] is returned.
    *
-   * If [start] is not provided, it defaults to [:this.length - 1:].
+   *     List<String> notes = ['do', 're', 'mi', 're'];
+   *     notes.lastIndexOf('re', 2); // 1
+   *
+   * If [start] is not provided, this method searches from the end of the
+   * list./Returns
+   *
+   *     notes.lastIndexOf('re');  // 3
    *
    * Returns -1 if [element] is not found.
+   *
+   *     notes.lastIndexOf('fa');  // -1
    */
   int lastIndexOf(E element, [int start]);
 
   /**
    * Removes all objects from this list;
    * the length of the list becomes zero.
    *
    * Throws an [UnsupportedError], and retains all objects, if this
    * is a fixed-length list.
    */
@@ skipping 18 matching lines @@
    *
    * An error occurs if the [index] is less than 0 or greater than length.
    * An [UnsupportedError] occurs if the list is fixed-length.
    */
   void insertAll(int index, Iterable<E> iterable);
 
   /**
    * Overwrites objects of `this` with the objects of [iterable], starting
    * at position [index] in this list.
    *
+   *     List<String> list = ['a', 'b', 'c'];
+   *     list.setAll(1, ['bee', 'sea']);
+   *     list.join(', '); // 'a, bee, sea'
+   *
    * This operation does not increase the length of `this`.
    *
    * An error occurs if the [index] is less than 0 or greater than length.
    * An error occurs if the [iterable] is longer than [length] - [index].
    */
   void setAll(int index, Iterable<E> iterable);
 
   /**
    * Removes the first occurence of [value] from this list.
    *
-   * Returns true if [value] was in the list.
-   * Returns false otherwise.
+   * Returns true if [value] was in the list, false otherwise.
+   *
+   *     List<String> parts = ['head', 'shoulders', 'knees', 'toes'];
+   *     parts.remove('head'); // true
+   *     parts.join(', ');     // 'shoulders, knees, toes'
    *
    * The method has no effect if [value] was not in the list.
    *
+   *     // Note: 'head' has already been removed.
+   *     parts.remove('head'); // false
+   *     parts.join(', ');     // 'shoulders, knees, toes'
+   *
    * An [UnsupportedError] occurs if the list is fixed-length.
    */
   bool remove(Object value);
 
   /**
    * Removes the object at position [index] from this list.
    *
    * This method reduces the length of `this` by one and moves all later objects
    * down by one position.
    *
@@ skipping 11 matching lines @@
    *
    * Throws an [UnsupportedError] if this is a fixed-length list.
    */
   E removeLast();
 
   /**
    * Removes all objects from this list that satisfy [test].
    *
    * An object [:o:] satisfies [test] if [:test(o):] is true.
    *
+   *     List<String> numbers = ['one', 'two', 'three', 'four'];
+   *     numbers.removeWhere((item) => item.length == 3);
+   *     numbers.join(', '); // 'three, four'
+   *
    * Throws an [UnsupportedError] if this is a fixed-length list.
    */
   void removeWhere(bool test(E element));
 
   /**
    * Removes all objects from this list that fail to satisfy [test].
    *
    * An object [:o:] satisfies [test] if [:test(o):] is true.
    *
+   *     List<String> numbers = ['one', 'two', 'three', 'four'];
+   *     numbers.retainWhere((item) => item.length == 3);
+   *     numbers.join(', '); // 'one, two'
+   *
    * Throws an [UnsupportedError] if this is a fixed-length list.
    */
   void retainWhere(bool test(E element));
 
   /**
-   * Returns a new list containing the objects
-   * from [start] inclusive to [end] exclusive.
+   * Returns a new list containing the objects from [start] inclusive to [end]
+   * exclusive.
+   *
+   *     List<String> colors = ['red', 'green', 'blue', 'orange', 'pink'];
+   *     colors.sublist(1, 3); // ['green', 'blue']
    *
    * If [end] is omitted, the [length] of `this` is used.
    *
+   *     colors.sublist(1);  // ['green', 'blue', 'orange', 'pink']
+   *
    * An error occurs if [start] is outside the range `0` .. `length` or if
    * [end] is outside the range `start` .. `length`.
    */
   List<E> sublist(int start, [int end]);
 
   /**
    * Returns an [Iterable] that iterates over the objects in the range
    * [start] inclusive to [end] exclusive.
    *
    * An error occurs if [end] is before [start].
    *
    * An error occurs if the [start] and [end] are not valid ranges at the time
    * of the call to this method. The returned [Iterable] behaves like
    * `skip(start).take(end - start)`. That is, it does not throw exceptions
    * if `this` changes size.
    *
-   * Example:
-   *
-   *     var list = [1, 2, 3, 4, 5];
-   *     var range = list.getRange(1, 4);
-   *     print(range.join(', '));  // => 2, 3, 4
-   *     list.length = 3;
-   *     print(range.join(', '));  // => 2, 3
+   *     List<String> colors = ['red', 'green', 'blue', 'orange', 'pink'];
+   *     Iterable<String> range = colors.getRange(1, 4);
+   *     range.join(', ');  // 'green, blue, orange'
+   *     colors.length = 3;
+   *     range.join(', ');  // 'green, blue'
    */
   Iterable<E> getRange(int start, int end);
 
   /**
    * Copies the objects of [iterable], skipping [skipCount] objects first,
    * into the range [start] inclusive to [end] exclusive of `this`.
    *
+   *     List<int> list1 = [1, 2, 3, 4];
+   *     List<int> list2 = [5, 6, 7, 8, 9];
+   *     // Copies the 4th and 5th items in list2 as the 2nd and 3rd items
+   *     // of list1.
+   *     list1.setRange(1, 3, list2, 3);
+   *     list1.join(', '); // '1, 8, 9, 4'
+   *
    * If [start] equals [end] and [start]..[end] represents a legal range, this
    * method has no effect.
    *
    * An error occurs if [start]..[end] is not a valid range for `this`.
    * An error occurs if the [iterable] does not have enough objects after
    * skipping [skipCount] objects.
    *
-   * Example:
-   *
-   *     var list = [1, 2, 3, 4];
-   *     var list2 = [5, 6, 7, 8, 9];
-   *     list.setRange(1, 3, list2, 3);
-   *     print(list);  // => [1, 8, 9, 4]
    */
   void setRange(int start, int end, Iterable<E> iterable, [int skipCount = 0]);
 
   /**
    * Removes the objects in the range [start] inclusive to [end] exclusive.
    *
    * An error occurs if [start]..[end] is not a valid range for `this`.
    * Throws an [UnsupportedError] if this is a fixed-length list.
    */
   void removeRange(int start, int end);
 
   /**
    * Sets the objects in the range [start] inclusive to [end] exclusive
    * to the given [fillValue].
    *
    * An error occurs if [start]..[end] is not a valid range for `this`.
    */
   void fillRange(int start, int end, [E fillValue]);
 
   /**
    * Removes the objects in the range [start] inclusive to [end] exclusive
    * and replaces them with the contents of the [iterable].
    *
+   *     List<int> list = [1, 2, 3, 4];
+   *     list.replaceRange(1, 3, [6, 7]);
+   *     list.join(', '); // '1, 6, 7, 4'
+   *
    * An error occurs if [start]..[end] is not a valid range for `this`.
-   *
-   * Example:
-   *
-   *     var list = [1, 2, 3, 4, 5];
-   *     list.replaceRange(1, 3, [6, 7, 8, 9]);
-   *     print(list);  // [1, 6, 7, 8, 9, 4, 5]
    */
   void replaceRange(int start, int end, Iterable<E> iterable);
 
   /**
    * Returns an unmodifiable [Map] view of `this`.
    *
    * The map uses the indices of this list as keys and the corresponding objects
    * as values. The `Map.keys` [Iterable] iterates the indices of this list
    * in numerical order.
+   *
+   *     List<String> words = ['fee', 'fi', 'fo', 'fum'];
+   *     Map<int, String> map = words.asMap();
+   *     map[0] + map[1];   // 'feefi';
+   *     map.keys.toList(); // [0, 1, 2, 3]
    */
   Map<int, E> asMap();
 }