Move Iterable implementation to collection.

sdk/lib/collection/iterable.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.collection;
+
+/**
+ * This [Iterable] mixin implements all [Iterable] members except `iterator`.
+ *
+ * All other methods are implemented in terms of `iterator`.
+ */
+abstract class IterableMixin<E> implements Iterable<E> {
+  Iterable map(f(E element)) => new MappedIterable<E, dynamic>(this, f);
+
+  Iterable<E> where(bool f(E element)) => new WhereIterable<E>(this, f);
+
+  Iterable expand(Iterable f(E element)) =>
+      new ExpandIterable<E, dynamic>(this, f);
+
+  bool contains(E element) {
+    for (E e in this) {
+      if (e == element) return true;
+    }
+    return false;
+  }
+
+  void forEach(void f(E element)) {
+    for (E element in this) f(element);
+  }
+
+  E reduce(E combine(E value, E element)) {
+    Iterator<E> iterator = this.iterator;
+    if (!iterator.moveNext()) {
+      throw new StateError("No elements");
+    }
+    E value = iterator.current;
+    while (iterator.moveNext()) {
+      value = combine(value, iterator.current);
+    }
+    return value;
+  }
+
+  dynamic fold(var initialValue,
+               dynamic combine(var previousValue, E element)) {
+    var value = initialValue;
+    for (E element in this) value = combine(value, element);
+    return value;
+  }
+
+  bool every(bool f(E element)) {
+    for (E element in this) {
+      if (!f(element)) return false;
+    }
+    return true;
+  }
+
+  String join([String separator]) {
+    Iterator<E> iterator = this.iterator;
+    if (!iterator.moveNext()) return "";
+    StringBuffer buffer = new StringBuffer();
+    if (separator == null || separator == "") {
+      do {
+        buffer.write("${iterator.current}");
+      } while (iterator.moveNext());
+    } else {
+      buffer.write("${iterator.current}");
+      while (iterator.moveNext()) {
+        buffer.write(separator);
+        buffer.write("${iterator.current}");
+      }
+    }
+    return buffer.toString();
+  }
+
+  bool any(bool f(E element)) {
+    for (E element in this) {
+      if (f(element)) return true;
+    }
+    return false;
+  }
+
+  List<E> toList({ bool growable: true }) =>
+      new List<E>.from(this, growable: growable);
+
+  Set<E> toSet() => new Set<E>.from(this);
+
+  int get length {
+    int count = 0;
+    Iterator it = iterator;
+    while (it.moveNext()) {
+      count++;
+    }
+    return count;
+  }
+
+  bool get isEmpty => !iterator.moveNext();
+
+  Iterable<E> take(int n) {
+    return new TakeIterable<E>(this, n);
+  }
+
+  Iterable<E> takeWhile(bool test(E value)) {
+    return new TakeWhileIterable<E>(this, test);
+  }
+
+  Iterable<E> skip(int n) {
+    return new SkipIterable<E>(this, n);
+  }
+
+  Iterable<E> skipWhile(bool test(E value)) {
+    return new SkipWhileIterable<E>(this, test);
+  }
+
+  E get first {
+    Iterator it = iterator;
+    if (!it.moveNext()) {
+      throw new StateError("No elements");
+    }
+    return it.current;
+  }
+
+  E get last {
+    Iterator it = iterator;
+    if (!it.moveNext()) {
+      throw new StateError("No elements");
+    }
+    E result;
+    do {
+      result = it.current;
+    } while(it.moveNext());
+    return result;
+  }
+
+  E get single {
+    Iterator it = iterator;
+    if (!it.moveNext()) throw new StateError("No elements");
+    E result = it.current;
+    if (it.moveNext()) throw new StateError("More than one element");
+    return result;
+  }
+
+  E firstWhere(bool test(E value), { E orElse() }) {
+    // TODO(floitsch): check that arguments are of correct type?
+    for (E element in this) {
+      if (test(element)) return element;
+    }
+    if (orElse != null) return orElse();
+    throw new StateError("No matching element");
+  }
+
+  E lastWhere(bool test(E value), {E orElse()}) {
+    // TODO(floitsch): check that arguments are of correct type?
+    E result = null;
+    bool foundMatching = false;
+    for (E element in this) {
+      if (test(element)) {
+        result = element;
+        foundMatching = true;
+      }
+    }
+    if (foundMatching) return result;
+    if (orElse != null) return orElse();
+    throw new StateError("No matching element");
+  }
+
+  E singleWhere(bool test(E value)) {
+    // TODO(floitsch): check that argument is of correct type?
+    E result = null;
+    bool foundMatching = false;
+    for (E element in this) {
+      if (test(element)) {
+        if (foundMatching) {
+          throw new StateError("More than one matching element");
+        }
+        result = element;
+        foundMatching = true;
+      }
+    }
+    if (foundMatching) return result;
+    throw new StateError("No matching element");
+  }
+
+  E elementAt(int index) {
+    if (index is! int || index < 0) throw new RangeError.value(index);
+    int remaining = index;
+    for (E element in this) {
+      if (remaining == 0) return element;
+      remaining--;
+    }
+    throw new RangeError.value(index);
+  }
+}
+
+/**
+ * Base class for implementing [Iterable].
+ *
+ * This class implements all methods of [Iterable] except [Iterable.iterator]
+ * in terms of `iterator`.
+ */
+abstract class IterableBase<E> implements Iterable<E> {
+  // TODO(lrn): Base this on IterableMixin if there ever becomes a way
+  // to combine const constructors and mixins.
+  const IterableBase();
+
+  Iterable map(f(E element)) => new MappedIterable<E, dynamic>(this, f);
+
+  Iterable<E> where(bool f(E element)) => new WhereIterable<E>(this, f);
+
+  Iterable expand(Iterable f(E element)) =>
+      new ExpandIterable<E, dynamic>(this, f);
+
+  bool contains(E element) {
+    for (E e in this) {
+      if (e == element) return true;
+    }
+    return false;
+  }
+
+  void forEach(void f(E element)) {
+    for (E element in this) f(element);
+  }
+
+  E reduce(E combine(E value, E element)) {
+    Iterator<E> iterator = this.iterator;
+    if (!iterator.moveNext()) {
+      throw new StateError("No elements");
+    }
+    E value = iterator.current;
+    while (iterator.moveNext()) {
+      value = combine(value, iterator.current);
+    }
+    return value;
+  }
+
+  dynamic fold(var initialValue,
+               dynamic combine(var previousValue, E element)) {
+    var value = initialValue;
+    for (E element in this) value = combine(value, element);
+    return value;
+  }
+
+  bool every(bool f(E element)) {
+    for (E element in this) {
+      if (!f(element)) return false;
+    }
+    return true;
+  }
+
+  String join([String separator]) {
+    Iterator<E> iterator = this.iterator;
+    if (!iterator.moveNext()) return "";
+    StringBuffer buffer = new StringBuffer();
+    if (separator == null || separator == "") {
+      do {
+        buffer.write("${iterator.current}");
+      } while (iterator.moveNext());
+    } else {
+      buffer.write("${iterator.current}");
+      while (iterator.moveNext()) {
+        buffer.write(separator);
+        buffer.write("${iterator.current}");
+      }
+    }
+    return buffer.toString();
+  }
+
+  bool any(bool f(E element)) {
+    for (E element in this) {
+      if (f(element)) return true;
+    }
+    return false;
+  }
+
+  List<E> toList({ bool growable: true }) =>
+      new List<E>.from(this, growable: growable);
+
+  Set<E> toSet() => new Set<E>.from(this);
+
+  int get length {
+    int count = 0;
+    Iterator it = iterator;
+    while (it.moveNext()) {
+      count++;
+    }
+    return count;
+  }
+
+  bool get isEmpty => !iterator.moveNext();
+
+  Iterable<E> take(int n) {
+    return new TakeIterable<E>(this, n);
+  }
+
+  Iterable<E> takeWhile(bool test(E value)) {
+    return new TakeWhileIterable<E>(this, test);
+  }
+
+  Iterable<E> skip(int n) {
+    return new SkipIterable<E>(this, n);
+  }
+
+  Iterable<E> skipWhile(bool test(E value)) {
+    return new SkipWhileIterable<E>(this, test);
+  }
+
+  E get first {
+    Iterator it = iterator;
+    if (!it.moveNext()) {
+      throw new StateError("No elements");
+    }
+    return it.current;
+  }
+
+  E get last {
+    Iterator it = iterator;
+    if (!it.moveNext()) {
+      throw new StateError("No elements");
+    }
+    E result;
+    do {
+      result = it.current;
+    } while(it.moveNext());
+    return result;
+  }
+
+  E get single {
+    Iterator it = iterator;
+    if (!it.moveNext()) throw new StateError("No elements");
+    E result = it.current;
+    if (it.moveNext()) throw new StateError("More than one element");
+    return result;
+  }
+
+  E firstWhere(bool test(E value), { E orElse() }) {
+    // TODO(floitsch): check that arguments are of correct type?
+    for (E element in this) {
+      if (test(element)) return element;
+    }
+    if (orElse != null) return orElse();
+    throw new StateError("No matching element");
+  }
+
+  E lastWhere(bool test(E value), {E orElse()}) {
+    // TODO(floitsch): check that arguments are of correct type?
+    E result = null;
+    bool foundMatching = false;
+    for (E element in this) {
+      if (test(element)) {
+        result = element;
+        foundMatching = true;
+      }
+    }
+    if (foundMatching) return result;
+    if (orElse != null) return orElse();
+    throw new StateError("No matching element");
+  }
+
+  E singleWhere(bool test(E value)) {
+    // TODO(floitsch): check that argument is of correct type?
+    E result = null;
+    bool foundMatching = false;
+    for (E element in this) {
+      if (test(element)) {
+        if (foundMatching) {
+          throw new StateError("More than one matching element");
+        }
+        result = element;
+        foundMatching = true;
+      }
+    }
+    if (foundMatching) return result;
+    throw new StateError("No matching element");
+  }
+
+  E elementAt(int index) {
+    if (index is! int || index < 0) throw new RangeError.value(index);
+    int remaining = index;
+    for (E element in this) {
+      if (remaining == 0) return element;
+      remaining--;
+    }
+    throw new RangeError.value(index);
+  }
+}