tests/language_2/const_map_test.dart

// Copyright (c) 2014, 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";

/// Returns its argument.
///
/// Prevents static optimizations and inlining.
getValueNonOptimized(x) {
  // DateTime.now() cannot be predicted statically, never equal to ASCII 42 '*'.
  if (new DateTime.now() == 42) return getValueNonOptimized(2);
  return x;
}

main() {
  // TODO(terry): Should check:
  //   - const map is immutable
  //   - simple expressions are const e.g., 2 + 3, true && !false, etc.
  //   - const with final and/or static with same const attributes
  //     Additionally new class instances with a static const same identity
  //   - const for all types (int, num, double, String, boolean, and objects)
  //   - canonicalization - const created only once same identity e.g.,
  //
  //     getConstMap() => const [1, 2];
  //     var a = getConstMap();
  //     var b = getConstMap();
  //     Expect.equals(a.hashCode, b.hashCode);

  // Make sure that const maps use the == operator and not object identity. The
  // specification does not explicitly require it, otherwise ints and Strings
  // wouldn't make much sense as keys.
  var m = const {1: 42, "foo": 499, 2: "bar"};
  Expect.equals(42, m[getValueNonOptimized(1.0)]);
  Expect.equals(
      499, m[getValueNonOptimized(new String.fromCharCodes("foo".runes))]);
  Expect.equals('bar', m[getValueNonOptimized(2)]);
}