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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_WhileEmitter_h
#define frontend_WhileEmitter_h
#include "mozilla/Attributes.h"
#include "mozilla/Maybe.h"
#include <stdint.h>
#include "frontend/BytecodeControlStructures.h"
#include "frontend/TDZCheckCache.h"
namespace js {
namespace frontend {
struct BytecodeEmitter;
// Class for emitting bytecode for while loop.
//
// Usage: (check for the return value is omitted for simplicity)
//
// `while (cond) body`
// WhileEmitter wh(this);
// wh.emitCond(offset_of_while,
// offset_of_body,
// offset_of_end);
// emit(cond);
// wh.emitBody();
// emit(body);
// wh.emitEnd();
//
class MOZ_STACK_CLASS WhileEmitter {
BytecodeEmitter* bce_;
mozilla::Maybe<LoopControl> loopInfo_;
// Cache for the loop body, which is enclosed by the cache in `loopInfo_`,
// which is effectively for the loop condition.
mozilla::Maybe<TDZCheckCache> tdzCacheForBody_;
#ifdef DEBUG
// The state of this emitter.
//
// +-------+ emitCond +------+ emitBody +------+ emitEnd +-----+
// | Start |--------->| Cond |--------->| Body |--------->| End |
// +-------+ +------+ +------+ +-----+
enum class State {
// The initial state.
Start,
// After calling emitCond.
Cond,
// After calling emitBody.
Body,
// After calling emitEnd.
End
};
State state_ = State::Start;
#endif
public:
explicit WhileEmitter(BytecodeEmitter* bce);
// Parameters are the offset in the source code for each character below:
//
// while ( x < 20 ) { ... }
// ^ ^ ^
// | | |
// | | endPos_
// | |
// | condPos_
// |
// whilePos_
[[nodiscard]] bool emitCond(uint32_t whilePos, uint32_t condPos,
uint32_t endPos);
[[nodiscard]] bool emitBody();
[[nodiscard]] bool emitEnd();
};
} /* namespace frontend */
} /* namespace js */
#endif /* frontend_WhileEmitter_h */
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