Concept of how dart:mirrors LibraryMirror, ClassMirror can be implemented in dart2js.

tests/compiler/dart2js_extra/mirror_libraries_test.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.
+//
+// Test basic mirrors functionality.
+
+import 'dart:mirrors';
+import 'dart:isolate';
+
+import 'async_helper.dart';
+
+var simpleVar = 123;
+final finalVar = 456;
+
+dynamic functionDynamic() {
+  return 123;
+}
+int functionInt() {
+  return 456;
+}
+void functionVoid() {
+}
+
+class C_Used {
+  int xx;
+  set x(int _xx) { xx = _xx; }
+
+  int yy;
+  int ss;
+  int vv;
+  C_Used(this.xx, [this.ss = 128, this.vv = 256]) {
+    yy = 111;
+  }
+  C_Used.withOpts(this.xx, {var s : 1024, var v : 2048}) {
+    yy = 222; ss = s; vv = v;
+  }
+
+  String toString() => 'C_Used(xx=$xx, yy=$yy, ss=$ss, vv=$vv)';
+}
+class C1_NotUsed {}
+
+void test() {
+  MirrorSystem mirrorSystem = currentMirrorSystem();
+
+  for (LibraryMirror lm in mirrorSystem.libraries.values) {
+    print("${lm.simpleName}");
+    if (lm.classes != null) {
+      lm.classes.forEach(
+          (key, value) {
+            print("\tClass: $key\t${value == null?'':value}");
+            if (value.methods != null) {
+              value.methods.forEach(
+                  (key, value) => print("\t\tMethod: $key\t$value"));
+            }
+            if (value.getters != null) {
+              value.getters.forEach(
+                  (key, value) => print("\t\tGetter: $key\t$value"));
+            }
+            if (value.setters != null) {
+              value.setters.forEach(
+                  (key, value) => print("\t\tSetter: $key\t$value"));
+            }
+            if (value.variables != null) {
+              value.variables.forEach(
+                  (key, value) => print("\t\tVariable: $key\t$value"));
+            }
+            if (value.constructors != null) {
+              value.constructors.forEach(
+                  (key, value) => print("\t\tConstuctor: $key\t$value"));
+            }
+            if (value.typeVariables != null) {
+              value.typeVariables.forEach(
+                  (key, value) => print("\t\tTypeVariable: $key\t$value"));
+            }
+            if (value.typeArguments != null) {
+              value.typeArguments.forEach(
+                  (key, value) => print("\t\tTypeArgument: $key\t$value"));
+            }
+          });
+    }
+    if (lm.functions != null) {
+      lm.functions.forEach(
+          (key, value) => print("\tFunction: $key\t${value == null?'':value}"));
+    }
+    if (lm.variables != null) {
+      lm.variables.forEach(
+          (key, value) => print("\tVariable: $key\t${value == null?'':value}"));
+    }
+  }
+
+  Collection<LibraryMirror> libraries = mirrorSystem.libraries.values;
+  Expect.equals(1, libraries.filter(
+      (library) => library.simpleName == "dart.mirrors").length);
+  Collection<LibraryMirror> thisLibraryMirrors = 
+    libraries.filter(
+        (library) => library.simpleName.endsWith('mirror_libraries_test.dart'));
+  Expect.equals(1, thisLibraryMirrors.length);
+  LibraryMirror thisLibraryMirror = thisLibraryMirrors[0];
+  Expect.isTrue(thisLibraryMirror.classes.containsKey("C_Used"));
+  ClassMirror classMirror = thisLibraryMirror.classes["C_Used"];
+  Expect.equals(2, classMirror.constructors.length);
+  classMirror.constructors.forEach((name, constructorMirror) {
+    Expect.isNotNull(name);
+    Expect.isNotNull(constructorMirror.constructorName);
+    Expect.isTrue(constructorMirror.isConstructor);
+
+    asyncTest((onDone) {
+      classMirror.newInstance(
+            constructorMirror.constructorName,
+            [218],
+            null).then((value) {
+        Expect.equals(218, value.reflectee.xx);
+      });
+      onDone(true);
+    });
+  });
+
+  Expect.equals(4, classMirror.variables.length);
+  Expect.equals(1,
+      classMirror.variables.values.filter((v) => v.simpleName == "xx").length);
+  Expect.equals(1,
+      classMirror.variables.values.filter((v) => v.simpleName == "yy").length);
+  Expect.equals(1,
+      classMirror.variables.values.filter((v) => v.simpleName == "ss").length);
+  Expect.equals(1,
+      classMirror.variables.values.filter((v) => v.simpleName == "vv").length);
+
+  asyncTest((onDone) {
+    classMirror.newInstance("", [], null).then((value) {
+      Expect.isTrue(value.hasReflectee);
+    });
+    onDone(true);
+  });
+  asyncTest((onDone) {
+    classMirror.newInstance("", [], null).then((value) {
+      Expect.isNull(value.reflectee.xx);
+    });
+    onDone(true);
+  });
+  asyncTest((onDone) {
+    classMirror.newInstance("", [314], null).then((value) {
+      Expect.equals(314, value.reflectee.xx);
+    });
+    onDone(true);
+  });
+  asyncTest((onDone) {
+    classMirror.newInstance("", [314], null).then((value) {
+      Expect.equals(111, value.reflectee.yy);
+    });
+    onDone(true);
+  });
+  asyncTest((onDone) {
+    classMirror.newInstance("withOpts", [159], null).then((value) {
+      Expect.equals(159, value.reflectee.xx);
+    });
+    onDone(true);
+  });
+  asyncTest((onDone) {
+    classMirror.newInstance("withOpts", [26], null).then((value) {
+      Expect.equals(222, value.reflectee.yy);
+    });
+    onDone(true);
+  });
+
+  asyncTest((onDone) {
+    classMirror.newInstance("", [314, 159, 26], null).then((instance) {
+      asyncTest((onDone) {
+        instance.invoke("toString", []).then((value) {
+          Expect.equals(
+            "C_Used(xx=314, yy=111, ss=159, vv=26)",
+            value.reflectee);
+          onDone(true);
+        });
+      });
+    });
+    onDone(true);
+  });
+
+  Expect.equals(1,
+      thisLibraryMirror.variables.values.filter(
+          (v) => v.simpleName == "simpleVar").length);
+  VariableMirror variableMirror =
+      thisLibraryMirror.variables.values.filter(
+          (v) => v.simpleName == "simpleVar")[0];
+  Expect.isFalse(variableMirror.isStatic);
+  Expect.isFalse(variableMirror.isFinal);
+  Expect.equals(1,
+      thisLibraryMirror.variables.values.filter(
+          (v) => v.simpleName == "finalVar").length);
+  variableMirror =
+      thisLibraryMirror.variables.values.filter(
+          (v) => v.simpleName == "finalVar")[0];
+  Expect.isFalse(variableMirror.isStatic);
+  Expect.isTrue(variableMirror.isFinal);
+
+  Expect.isTrue(thisLibraryMirror.classes.containsKey("C1_NotUsed"));
+  classMirror = thisLibraryMirror.classes["C1_NotUsed"];
+  asyncTest((onDone) {
+    classMirror.newInstance("", [], null).then((value) {
+      Expect.isFalse(value.hasReflectee);
+    });
+    onDone(true);
+  });
+  asyncTest((onDone) {
+    classMirror.newInstance("", [], null).then((value) {
+      Expect.isNull(value.reflectee);
+    });
+    onDone(true);
+  });
+
+  Expect.isTrue(thisLibraryMirror.functions.containsKey("functionVoid"));
+  MethodMirror functionMirror = thisLibraryMirror.functions["functionVoid"];
+  Expect.equals(functionMirror.returnType, mirrorSystem.voidType);
+
+  Expect.isTrue(thisLibraryMirror.functions.containsKey("functionDynamic"));
+  functionMirror = thisLibraryMirror.functions["functionDynamic"];
+  Expect.equals(functionMirror.returnType, mirrorSystem.dynamicType);
+
+  Expect.isTrue(thisLibraryMirror.functions.containsKey("functionInt"));
+  functionMirror = thisLibraryMirror.functions["functionInt"];
+  Expect.isNotNull(functionMirror.returnType);
+}
+
+void main() {
+   // Dummy use to get class constructor generated.
+  new C_Used(123);
+  new C_Used.withOpts(456);
+
+  var result;
+  for (var i=0; i<123; i++) {
+    functionVoid();
+    result = functionDynamic();
+  }
+  print("$result");
+  for (var i=0; i<123; i++) {
+    result = functionInt();
+  }
+
+  print("""
+
+This program is using an experimental feature called \"mirrors\".  As
+currently implemented, mirrors do not work with minification, and will
+cause spurious errors depending on how code was optimized.
+
+The authors of this program are aware of these problems and have
+decided the thrill of using an experimental feature is outweighing the
+risks.  Furthermore, the authors of this program understand that
+long-term, to fix the problems mentioned above, mirrors may have
+negative impact on size and performance of Dart programs compiled to
+JavaScript.
+""");
+
+  test();
+}