Adds tests for syntactic support for generic methods.

tests/language/generic_methods_test.dart

+// Copyright (c) 2016, 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.
+
+import "package:expect/expect.dart";
+
+// Dart test verifying that the parser can handle type parameterization of
+// method declarations and method invocations. Slightly adjusted version of
+// code from DEP #22.
+
+class BinaryTreeNode<K extends Comparable<K>, V> {
+  final K _key;
+  final V _value;
+  final BinaryTreeNode<K, V> _left;
+  final BinaryTreeNode<K, V> _right;
+
+  BinaryTreeNode(this._key, this._value,
+      {BinaryTreeNode<K, V> left: null, BinaryTreeNode<K, V> right: null}) :
+          _left = left, _right = right;
+
+  // Use fresh type variables.
+  static BinaryTreeNode<K2, V2> insertOpt<K2 extends Comparable<K2>, V2>(
+      BinaryTreeNode<K2, V2> t, K2 key, V2 value) {
+    return (t == null) ? new BinaryTreeNode(key, value) : t.insert(key, value);
+  }
+
+  BinaryTreeNode<K, V> insert(K key, V value) {
+    int c = key.compareTo(_key);
+    if (c == 0) return this;
+    var _insert = (BinaryTreeNode<K, V> node, K key, V value) =>
+        insertOpt<K, V>(node, key, value);
+    BinaryTreeNode<K, V> left = _left;
+    BinaryTreeNode<K, V> right = _right;
+    if (c < 0) {
+      left = _insert(_left, key, value);
+    } else {
+      right = _insert(_right, key, value);
+    }
+    return new BinaryTreeNode<K, V>(_key, _value, left: left, right: right);
+  }
+
+  // Reuse type variables [K], [V] to test shadowing.
+  static BinaryTreeNode<K, U> mapOpt<K extends Comparable<K>, V, U>
+      (BinaryTreeNode<K, V> t, U f(V x)) {
+    return (t == null) ? null : t.map<U>(f);
+  }
+
+  BinaryTreeNode<K, U> map<U>(U f(V x)){
+    var _map = (BinaryTreeNode<K, V> t, U f(V x)) => mapOpt<K, V, U>(t, f);
+    return new BinaryTreeNode<K, U>(
+        _key,
+        f(_value),
+        left: _map(_left, f),
+        right: _map(_right, f));
+  }
+
+  // Use fresh [K2], shadowing [V].
+  static S foldPreOpt<K2 extends Comparable<K2>, V, S>(
+      BinaryTreeNode<K2, V> t, S init, S f(V t, S s)) {
+    return (t == null) ? init : t.foldPre<S>(init, f);
+  }
+
+  S foldPre<S>(S init, S f(V t, S s)) {
+    var _fold = (BinaryTreeNode<K, V> t, S s, S f(V t, S s)) =>
+        foldPreOpt<K, V, S>(t, s, f);
+    S s = init;
+    s = f(_value, s);
+    s = _fold(_left, s, f);
+    s = _fold(_right, s, f);
+    return s;
+  }
+}
+
+class BinaryTree<K extends Comparable<K>, V> {
+  final BinaryTreeNode<K, V> _root;
+
+  BinaryTree._internal(this._root);
+  BinaryTree.empty() : this._internal(null);
+
+  BinaryTree<K, V> insert(K key, V value) {
+    BinaryTreeNode<K, V> root =
+        BinaryTreeNode.insertOpt<K, V>(_root, key, value);
+    return new BinaryTree<K, V>._internal(root);
+  }
+
+  BinaryTree<K, U> map<U>(U f(V x)) {
+    BinaryTreeNode<K, U> root = BinaryTreeNode.mapOpt<K, V, U>(_root, f);
+    return new BinaryTree<K, U>._internal(root);
+  }
+
+  S foldPre<S>(S init, S f(V t, S s)) {
+    return BinaryTreeNode.foldPreOpt<K, V, S>(_root, init, f);
+  }
+}
+
+main() {
+  BinaryTree<num, String> sT = new BinaryTree<num, String>.empty();
+
+  sT = sT.insert(0, "");
+  sT = sT.insert(1, " ");
+  sT = sT.insert(2, "  ");
+  sT = sT.insert(3, "   ");
+
+  BinaryTree<num, num> iT = sT.map<num>((String s) => s.length);
+
+  Expect.equals(iT.foldPre<num>(0, (int i, num s) => i + s), 6);
+}