Migrate test block 113 to Dart 2.0.

tests/language/generic_functions_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.
-//
-// VMOptions=--generic-method-syntax
-
-/// Dart test verifying that the parser can handle type parameterization of
-/// function declarations and function invocations. Variant of code from
-/// DEP #22, adjusted to use generic top level functions.
-
-library generic_functions_test;
-
-import "package:expect/expect.dart";
-
-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;
-
-  BinaryTreeNode<K, V> insert(K key, V value) {
-    int c = key.compareTo(_key);
-    if (c == 0) return this;
-    var _insert = (BinaryTreeNode<K, V> t, K key, V value) =>
-        insertOpt<K, V>(t, 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);
-  }
-
-  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));
-  }
-
-  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;
-  }
-}
-
-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, U> mapOpt<K extends Comparable<K>, V, U>(
-    BinaryTreeNode<K, V> t, U f(V x)) {
-  return (t == null) ? null : t.map<U>(f);
-}
-
-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);
-}
-
-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 = 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 = 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 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);
-}