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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef frontend_ForOfEmitter_h
#define frontend_ForOfEmitter_h
#include "mozilla/Attributes.h" // MOZ_STACK_CLASS
#include "mozilla/Maybe.h" // mozilla::Maybe
#include <stdint.h> // int32_t
#include "frontend/ForOfLoopControl.h" // ForOfLoopControl
#include "frontend/IteratorKind.h" // IteratorKind
#include "frontend/SelfHostedIter.h" // SelfHostedIter
#include "frontend/TDZCheckCache.h" // TDZCheckCache
namespace js {
namespace frontend {
struct BytecodeEmitter;
class EmitterScope;
// Class for emitting bytecode for for-of loop.
//
// Usage: (check for the return value is omitted for simplicity)
//
// `for (init of iterated) body`
// // headLexicalEmitterScope: lexical scope for init
// ForOfEmitter forOf(this, headLexicalEmitterScope);
// forOf.emitIterated();
// emit(iterated);
// forOf.emitInitialize(offset_of_for);
// emit(init);
// forOf.emitBody();
// emit(body);
// forOf.emitEnd(offset_of_iterated);
//
class MOZ_STACK_CLASS ForOfEmitter {
BytecodeEmitter* bce_;
#ifdef DEBUG
// The stack depth before emitting IteratorNext code inside loop.
int32_t loopDepth_ = 0;
#endif
SelfHostedIter selfHostedIter_;
IteratorKind iterKind_;
mozilla::Maybe<ForOfLoopControl> loopInfo_;
// The lexical scope to be freshened for each iteration.
// See the comment in `emitBody` for more details.
const EmitterScope* headLexicalEmitterScope_;
// Cache for the iterated value.
// (The cache for the iteration body is inside `loopInfo_`)
mozilla::Maybe<TDZCheckCache> tdzCacheForIteratedValue_;
#ifdef DEBUG
// The state of this emitter.
//
// +-------+ emitIterated +----------+ emitInitialize +------------+
// | Start |------------->| Iterated |--------------->| Initialize |-+
// +-------+ +----------+ +------------+ |
// |
// +----------------------------------+
// |
// | emitBody +------+ emitEnd +-----+
// +----------| Body |--------->| End |
// +------+ +-----+
enum class State {
// The initial state.
Start,
// After calling emitIterated.
Iterated,
// After calling emitInitialize.
Initialize,
// After calling emitBody.
Body,
// After calling emitEnd.
End
};
State state_ = State::Start;
#endif
public:
ForOfEmitter(BytecodeEmitter* bce,
const EmitterScope* headLexicalEmitterScope,
SelfHostedIter selfHostedIter, IteratorKind iterKind);
// The offset in the source code for each character below:
//
// for ( var x of obj ) { ... }
// ^ ^
// | |
// | iteratedPos
// |
// forPos
[[nodiscard]] bool emitIterated();
[[nodiscard]] bool emitInitialize(uint32_t forPos);
[[nodiscard]] bool emitBody();
[[nodiscard]] bool emitEnd(uint32_t iteratedPos);
};
} /* namespace frontend */
} /* namespace js */
#endif /* frontend_ForOfEmitter_h */
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