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File: /home/fstrocco/Dart/dart/benchmark/compiler/lib/src/js_emitter/parameter_stub_generator.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. part of dart2js.js_emitter; class ParameterStubGenerator { static final Set<Selector> emptySelectorSet = new Set<Selector>(); final Namer namer; final Compiler compiler; final JavaScriptBackend backend; ParameterStubGenerator(this.compiler, this.namer, this.backend); Emitter get emitter => backend.emitter.emitter; CodeEmitterTask get emitterTask => backend.emitter; bool needsSuperGetter(FunctionElement element) => compiler.codegenWorld.methodsNeedingSuperGetter.contains(element); /** * Generates stubs to handle invocation of methods with optional * arguments. * * A method like `foo([x])` may be invoked by the following * calls: `foo(), foo(1), foo(x: 1)`. This method generates the stub for the * given [selector] and returns the generated [ParameterStubMethod]. * * Returns null if no stub is needed. * * Members may be invoked in two ways: directly, or through a closure. In the * latter case the caller invokes the closure's `call` method. This method * accepts two selectors. The returned stub method has the corresponding * name [ParameterStubMethod.name] and [ParameterStubMethod.callName] set if * the input selector is non-null (and the member needs a stub). */ ParameterStubMethod generateParameterStub(FunctionElement member, Selector selector, Selector callSelector) { CallStructure callStructure = selector.callStructure; FunctionSignature parameters = member.functionSignature; int positionalArgumentCount = callStructure.positionalArgumentCount; if (positionalArgumentCount == parameters.parameterCount) { assert(callStructure.isUnnamed); return null; } if (parameters.optionalParametersAreNamed && callStructure.namedArgumentCount == parameters.optionalParameterCount) { // If the selector has the same number of named arguments as the element, // we don't need to add a stub. The call site will hit the method // directly. return null; } JavaScriptConstantCompiler handler = backend.constants; List<String> names = callStructure.getOrderedNamedArguments(); bool isInterceptedMethod = backend.isInterceptedMethod(member); // If the method is intercepted, we need to also pass the actual receiver. int extraArgumentCount = isInterceptedMethod ? 1 : 0; // Use '$receiver' to avoid clashes with other parameter names. Using // '$receiver' works because namer.safeVariableName used for getting parameter // names never returns a name beginning with a single '$'. String receiverArgumentName = r'$receiver'; // The parameters that this stub takes. List<jsAst.Parameter> parametersBuffer = new List<jsAst.Parameter>(selector.argumentCount + extraArgumentCount); // The arguments that will be passed to the real method. List<jsAst.Expression> argumentsBuffer = new List<jsAst.Expression>( parameters.parameterCount + extraArgumentCount); int count = 0; if (isInterceptedMethod) { count++; parametersBuffer[0] = new jsAst.Parameter(receiverArgumentName); argumentsBuffer[0] = js('#', receiverArgumentName); } int optionalParameterStart = positionalArgumentCount + extraArgumentCount; // Includes extra receiver argument when using interceptor convention int indexOfLastOptionalArgumentInParameters = optionalParameterStart - 1; int parameterIndex = 0; parameters.orderedForEachParameter((ParameterElement element) { String jsName = backend.namer.safeVariableName(element.name); assert(jsName != receiverArgumentName); if (count < optionalParameterStart) { parametersBuffer[count] = new jsAst.Parameter(jsName); argumentsBuffer[count] = js('#', jsName); } else { int index = names.indexOf(element.name); if (index != -1) { indexOfLastOptionalArgumentInParameters = count; // The order of the named arguments is not the same as the // one in the real method (which is in Dart source order). argumentsBuffer[count] = js('#', jsName); parametersBuffer[optionalParameterStart + index] = new jsAst.Parameter(jsName); } else { ConstantExpression constant = handler.getConstantForVariable(element); if (constant == null) { argumentsBuffer[count] = emitter.constantReference(new NullConstantValue()); } else { ConstantValue value = constant.value; if (!value.isNull) { // If the value is the null constant, we should not pass it // down to the native method. indexOfLastOptionalArgumentInParameters = count; } argumentsBuffer[count] = emitter.constantReference(value); } } } count++; }); var body; // List or jsAst.Statement. if (member.hasFixedBackendName) { body = emitterTask.nativeEmitter.generateParameterStubStatements( member, isInterceptedMethod, namer.invocationName(selector), parametersBuffer, argumentsBuffer, indexOfLastOptionalArgumentInParameters); } else if (member.isInstanceMember) { if (needsSuperGetter(member)) { ClassElement superClass = member.enclosingClass; String methodName = namer.instanceMethodName(member); // When redirecting, we must ensure that we don't end up in a subclass. // We thus can't just invoke `this.foo$1.call(filledInArguments)`. // Instead we need to call the statically resolved target. // `<class>.prototype.bar$1.call(this, argument0, ...)`. body = js.statement( 'return #.#.call(this, #);', [backend.emitter.prototypeAccess(superClass, hasBeenInstantiated: true), methodName, argumentsBuffer]); } else { body = js.statement( 'return this.#(#);', [namer.instanceMethodName(member), argumentsBuffer]); } } else { body = js.statement('return #(#)', [emitter.staticFunctionAccess(member), argumentsBuffer]); } jsAst.Fun function = js('function(#) { #; }', [parametersBuffer, body]); String name = namer.invocationName(selector); String callName = (callSelector != null) ? namer.invocationName(callSelector) : null; return new ParameterStubMethod(name, callName, function); } // We fill the lists depending on possible/invoked selectors. For example, // take method foo: // foo(a, b, {c, d}); // // We may have multiple ways of calling foo: // (1) foo(1, 2); // (2) foo(1, 2, c: 3); // (3) foo(1, 2, d: 4); // (4) foo(1, 2, c: 3, d: 4); // (5) foo(1, 2, d: 4, c: 3); // // What we generate at the call sites are: // (1) foo$2(1, 2); // (2) foo$3$c(1, 2, 3); // (3) foo$3$d(1, 2, 4); // (4) foo$4$c$d(1, 2, 3, 4); // (5) foo$4$c$d(1, 2, 3, 4); // // The stubs we generate are (expressed in Dart): // (1) foo$2(a, b) => foo$4$c$d(a, b, null, null) // (2) foo$3$c(a, b, c) => foo$4$c$d(a, b, c, null); // (3) foo$3$d(a, b, d) => foo$4$c$d(a, b, null, d); // (4) No stub generated, call is direct. // (5) No stub generated, call is direct. // // We need to pay attention if this stub is for a function that has been // invoked from a subclass. Then we cannot just redirect, since that // would invoke the methods of the subclass. We have to compile to: // (1) foo$2(a, b) => MyClass.foo$4$c$d.call(this, a, b, null, null) // (2) foo$3$c(a, b, c) => MyClass.foo$4$c$d(this, a, b, c, null); // (3) foo$3$d(a, b, d) => MyClass.foo$4$c$d(this, a, b, null, d); List<ParameterStubMethod> generateParameterStubs(MethodElement member, {bool canTearOff: true}) { if (member.enclosingElement.isClosure) { ClosureClassElement cls = member.enclosingElement; if (cls.supertype.element == backend.boundClosureClass) { compiler.internalError(cls.methodElement, 'Bound closure1.'); } if (cls.methodElement.isInstanceMember) { compiler.internalError(cls.methodElement, 'Bound closure2.'); } } // The set of selectors that apply to `member`. For example, for // a member `foo(x, [y])` the following selectors may apply: // `foo(x)`, and `foo(x, y)`. Set<Selector> selectors; // The set of selectors that apply to `member` if it's name was `call`. // This happens when a member is torn off. In that case calls to the // function use the name `call`, and we must be able to handle every // `call` invocation that matches the signature. For example, for // a member `foo(x, [y])` the following selectors would be possible // call-selectors: `call(x)`, and `call(x, y)`. Set<Selector> callSelectors; // Only instance members (not static methods) need stubs. if (member.isInstanceMember) { selectors = compiler.codegenWorld.invokedNames[member.name]; } if (canTearOff) { String call = namer.closureInvocationSelectorName; callSelectors = compiler.codegenWorld.invokedNames[call]; } assert(emptySelectorSet.isEmpty); if (selectors == null) selectors = emptySelectorSet; if (callSelectors == null) callSelectors = emptySelectorSet; List<ParameterStubMethod> stubs = <ParameterStubMethod>[]; if (selectors.isEmpty && callSelectors.isEmpty) { return stubs; } // For every call-selector the corresponding selector with the name of the // member. // // For example, for the call-selector `call(x, y)` the renamed selector // for member `foo` would be `foo(x, y)`. Set<Selector> renamedCallSelectors = callSelectors.isEmpty ? emptySelectorSet : new Set<Selector>(); Set<Selector> untypedSelectors = new Set<Selector>(); // Start with the callSelectors since they imply the generation of the // non-call version. for (Selector selector in callSelectors) { Selector renamedSelector = new Selector( SelectorKind.CALL, member.memberName, selector.callStructure); renamedCallSelectors.add(renamedSelector); if (!renamedSelector.appliesUnnamed(member, compiler.world)) continue; if (untypedSelectors.add(renamedSelector.asUntyped)) { ParameterStubMethod stub = generateParameterStub(member, renamedSelector, selector); if (stub != null) { stubs.add(stub); } } } // Now run through the actual member selectors (eg. `foo$2(x, y)` and not // `call$2(x, y)`. Some of them have already been generated because of the // call-selectors (and they are in the renamedCallSelectors set. for (Selector selector in selectors) { if (renamedCallSelectors.contains(selector)) continue; if (!selector.appliesUnnamed(member, compiler.world)) continue; if (untypedSelectors.add(selector.asUntyped)) { ParameterStubMethod stub = generateParameterStub(member, selector, null); if (stub != null) { stubs.add(stub); } } } return stubs; } }