packages/quiver/lib/mirrors.dart

// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

library quiver.mirrors;

import 'dart:mirrors';

/// Returns the qualified name of [t].
Symbol getTypeName(Type t) => reflectClass(t).qualifiedName;

/// Returns true if [o] implements [type].
bool implements(Object o, Type type) =>
    classImplements(reflect(o).type, reflectClass(type));

/// Returns true if the class represented by [classMirror] implements the class
/// represented by [interfaceMirror].
bool classImplements(ClassMirror classMirror, ClassMirror interfaceMirror) {
  if (classMirror == null) return false;
  // TODO: change to comparing mirrors when dartbug.com/19781 is fixed
  if (classMirror.qualifiedName == interfaceMirror.qualifiedName) return true;
  if (classImplements(classMirror.superclass, interfaceMirror)) return true;
  if (classMirror.superinterfaces
      .any((i) => classImplements(i, interfaceMirror))) return true;
  return false;
}

/// Walks up the class hierarchy to find a method declaration with the given
/// [name].
///
/// Note that it's not possible to tell if there's an implementation via
/// noSuchMethod().
DeclarationMirror getDeclaration(ClassMirror classMirror, Symbol name) {
  if (classMirror.declarations.containsKey(name)) {
    return classMirror.declarations[name];
  }
  if (classMirror.superclass != null) {
    var mirror = getDeclaration(classMirror.superclass, name);
    if (mirror != null) {
      return mirror;
    }
  }
  for (ClassMirror supe in classMirror.superinterfaces) {
    var mirror = getDeclaration(supe, name);
    if (mirror != null) {
      return mirror;
    }
  }
  return null;
}

/// Closurizes a method reflectively.
class Method /* implements Function */ {
  final InstanceMirror mirror;
  final Symbol symbol;

  Method(this.mirror, this.symbol);

  dynamic noSuchMethod(Invocation i) {
    if (i.isMethod && i.memberName == const Symbol('call')) {
      if (i.namedArguments != null && i.namedArguments.isNotEmpty) {
        // this will fail until named argument support is implemented
        return mirror
            .invoke(symbol, i.positionalArguments, i.namedArguments)
            .reflectee;
      }
      return mirror.invoke(symbol, i.positionalArguments).reflectee;
    }
    return super.noSuchMethod(i);
  }
}