Jenny Messerly
384678e4b3
Change-Id: I2b6a5f56a69f5d3a965aefc3f8d4550d5940ac5a Reviewed-on: https://dart-review.googlesource.com/17980 Reviewed-by: Vijay Menon <vsm@google.com> Reviewed-by: Bob Nystrom <rnystrom@google.com> Reviewed-by: Leaf Petersen <leafp@google.com>
57 lines
1.9 KiB
Dart
57 lines
1.9 KiB
Dart
// Copyright (c) 2017, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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import '../js_ast/js_ast.dart';
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/// Simplify `(args) => (() => { ... })()` to `(args) => { ... }`.
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// TODO(jmesserly): find a better home for this function
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Fun simplifyPassThroughArrowFunCallBody(Fun fn) {
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if (fn.body is Block && fn.body.statements.length == 1) {
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var stat = fn.body.statements.single;
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if (stat is Return && stat.value is Call) {
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Call call = stat.value;
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if (call.target is ArrowFun && call.arguments.isEmpty) {
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ArrowFun innerFun = call.target;
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if (innerFun.params.isEmpty) {
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return new Fun(fn.params, innerFun.body,
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typeParams: fn.typeParams, returnType: fn.returnType);
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}
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}
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}
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}
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return fn;
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}
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/// Transform the function so the last parameter is always returned.
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///
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/// This is useful for indexed set methods, which otherwise would not have
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/// the right return value in JS.
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Block alwaysReturnLastParameter(Block body, Parameter lastParam) {
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Statement blockBody = body;
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if (Return.foundIn(body)) {
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// If a return is inside body, transform `(params) { body }` to
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// `(params) { (() => { body })(); return value; }`.
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// TODO(jmesserly): we could instead generate the return differently,
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// and avoid the immediately invoked function.
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blockBody = new Call(new ArrowFun([], body), []).toStatement();
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}
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return new Block([blockBody, new Return(lastParam)]);
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}
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Set<Identifier> findMutatedVariables(Node scope) {
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var v = new MutationVisitor();
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scope.accept(v);
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return v.mutated;
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}
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class MutationVisitor extends BaseVisitor {
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final mutated = new Set<Identifier>();
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@override
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visitAssignment(node) {
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var id = node.leftHandSide;
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if (id is Identifier) mutated.add(id);
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super.visitAssignment(node);
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}
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}
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