dart2js: add initial support for lookup-maps

tests/compiler/dart2js/lookup_map_test.dart

+// Copyright (c) 2015, 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.
+
+library tests.dart2js.lookup_map_test;
+
+import 'package:test/test.dart';
+import 'compiler_helper.dart';
+
+main() {
+  test('live entries are kept', () async {
+    String generated = await compileAll(r"""
+        import 'package:lookup_map/lookup_map.dart';
+        class A{}
+        const map = const LookupMap(const [
+            A, "the-text-for-A",
+        ]);
+        main() => print(map[A]);
+    """);
+    expect(generated, contains("the-text-for-A"));
+  });
+
+  test('live entries are kept - single-pair', () async {
+    String generated = await compileAll(r"""
+        import 'package:lookup_map/lookup_map.dart';
+        class A{}
+        const map = const LookupMap.pair(A, "the-text-for-A");
+        main() => print(map[A]);
+    """);
+    expect(generated, contains("the-text-for-A"));
+  });
+
+  test('unused entries are removed', () async {
+    String generated = await compileAll(r"""
+        import 'package:lookup_map/lookup_map.dart';
+        class A{}
+        class B{}
+        const map = const LookupMap(const [
+            A, "the-text-for-A",
+            B, "the-text-for-B",
+        ]);
+        main() => print(map[A]);
+    """);
+    expect(generated, isNot(contains("the-text-for-B")));
+  });
+
+  test('unused entries are removed - nested maps', () async {
+    String generated = await compileAll(r"""
+        import 'package:lookup_map/lookup_map.dart';
+        class A{}
+        class B{}
+        const map = const LookupMap(const [], const [
+          const LookupMap(const [
+              A, "the-text-for-A",
+              B, "the-text-for-B",
+          ]),
+        ]);
+        main() => print(map[A]);
+    """);
+    expect(generated, isNot(contains("the-text-for-B")));
+  });
+
+  test('unused entries are removed - single-pair', () async {
+    String generated = await compileAll(r"""
+        import 'package:lookup_map/lookup_map.dart';
+        class A{}
+        class B{}
+        const map = const LookupMap.pair(A, "the-text-for-A");
+        main() => print(map[A]);
+    """);
+    expect(generated, isNot(contains("the-text-for-B")));
+  });
+
+  test('unused entries are removed - nested single-pair', () async {
+    String generated = await compileAll(r"""
+        import 'package:lookup_map/lookup_map.dart';
+        class A{}
+        class B{}
+        const map = const LookupMap(const [], const [
+          const LookupMap.pair(A, "the-text-for-A"),
+          const LookupMap.pair(B, "the-text-for-B"),
+        ]);
+        main() => print(map[A]);
+    """);
+    expect(generated, isNot(contains("the-text-for-B")));
+  });
+
+  test('works if entries are declared separate from map', () async {
+    String generated = await compileAll(r"""
+        import 'package:lookup_map/lookup_map.dart';
+        class A{}
+        class B{}
+        const entries = const [
+            A, "the-text-for-A",
+            B, "the-text-for-B",
+        ];
+        const map = const LookupMap(entries);
+        main() => print(map[A]);
+    """);
+    expect(generated, isNot(contains("the-text-for-B")));
+  });
+
+  test('escaping entries disable tree-shaking', () async {
+    String generated = await compileAll(r"""
+        import 'package:lookup_map/lookup_map.dart';
+        class A{}
+        class B{}
+        const entries = const [
+            A, "the-text-for-A",
+            B, "the-text-for-B",
+        ];
+        const map = const LookupMap(entries);
+        main() {
+          entries.forEach(print);
+          print(map[A]);
+        }
+    """);
+    expect(generated, contains("the-text-for-B"));
+  });
+
+  test('uses include recursively reachable data', () async {
+    String generated = await compileAll(r"""
+        import 'package:lookup_map/lookup_map.dart';
+        class A{}
+        class B{}
+        class C{}
+        class D{}
+        class E{}
+        const map = const LookupMap(const [
+            A, const ["the-text-for-A", B],
+            B, const ["the-text-for-B", C],
+            C, const ["the-text-for-C"],
+            D, const ["the-text-for-D", E],
+            E, const ["the-text-for-E"],
+        ]);
+        main() => print(map[map[A][1]]);
+    """);
+    expect(generated, contains("the-text-for-A"));
+    expect(generated, contains("the-text-for-B"));
+    expect(generated, contains("the-text-for-C"));
+    expect(generated, isNot(contains("the-text-for-D")));
+    expect(generated, isNot(contains("the-text-for-E")));
+  });
+
+  test('uses are found through newly discovered code', () async {
+    String generated = await compileAll(r"""
+        import 'package:lookup_map/lookup_map.dart';
+        class A{ A(B x);}
+        class B{}
+        class C{}
+        class D{}
+        class E{}
+        createA() => new A(map[B][1]());
+        createB() => new B();
+        const map = const LookupMap(const [
+            A, const ["the-text-for-A", createA],
+            B, const ["the-text-for-B", createB],
+            C, const ["the-text-for-C"],
+        ]);
+        main() => print(map[A][1]());
+    """);
+    expect(generated, contains("the-text-for-A"));
+    expect(generated, contains("the-text-for-B"));
+    expect(generated, isNot(contains("the-text-for-C")));
+  });
+
+  test('generic types are considered used', () async {
+    String generated = await compileAll(r"""
+        import 'package:lookup_map/lookup_map.dart';
+        class A{}
+        class M<T>{ get type => T; }
+        const map = const LookupMap(const [
+            A, "the-text-for-A",
+        ]);
+        main() => print(map[new M<A>().type]);
+    """);
+    expect(generated, contains("the-text-for-A"));
+  });
+
+  // regression test for a failure when looking up `dynamic` in a generic.
+  test('do not choke on dynamic types', () async {
+    await compileAll(r"""
+        import 'package:lookup_map/lookup_map.dart';
+        class A{}
+        class M<T>{ get type => T; }
+        const map = const LookupMap(const [
+            A, "the-text-for-A",
+        ]);
+        main() => print(map[new M<dynamic>().type]);
+    """);
+  });
+
+
+  test('support subclassing LookupMap', () async {
+    String generated = await compileAll(r"""
+        import 'package:lookup_map/lookup_map.dart';
+        class A{}
+        class B{}
+        class S extends LookupMap {
+          const S(list) : super(list);
+        }
+        const map = const S(const [
+            A, "the-text-for-A",
+            B, "the-text-for-B",
+        ]);
+
+        main() => print(map[A]);
+    """);
+    expect(generated, contains("the-text-for-A"));
+    expect(generated, isNot(contains("the-text-for-B")));
+  });
+}