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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_ExpressionStatementEmitter_h
#define frontend_ExpressionStatementEmitter_h
#include "mozilla/Attributes.h"
#include "mozilla/Maybe.h"
#include <stdint.h>
#include "frontend/ValueUsage.h"
namespace js {
namespace frontend {
struct BytecodeEmitter;
// Class for emitting bytecode for expression statement.
//
// Usage: (check for the return value is omitted for simplicity)
//
// `expr;`
// // IgnoreValue if this is in normal script.
// // WantValue if this is in eval script.
// ValueUsage valueUsage = ...;
//
// ExpressionStatementEmitter ese(this, valueUsage);
// ese.prepareForExpr(Some(offset_of_expr));
// emit(expr);
// ese.emitEnd();
//
class MOZ_STACK_CLASS ExpressionStatementEmitter {
BytecodeEmitter* bce_;
#ifdef DEBUG
// The stack depth before emitting expression.
int32_t depth_;
#endif
// The usage of the value of the expression.
ValueUsage valueUsage_;
#ifdef DEBUG
// The state of this emitter.
//
// +-------+ prepareForExpr +------+ emitEnd +-----+
// | Start |--------------->| Expr |-------->| End |
// +-------+ +------+ +-----+
enum class State {
// The initial state.
Start,
// After calling prepareForExpr.
Expr,
// After calling emitEnd.
End
};
State state_ = State::Start;
#endif
public:
ExpressionStatementEmitter(BytecodeEmitter* bce, ValueUsage valueUsage);
// Parameters are the offset in the source code for each character below:
//
// expr;
// ^
// |
// beginPos
//
// Can be Nothing() if not available.
MOZ_MUST_USE bool prepareForExpr(const mozilla::Maybe<uint32_t>& beginPos);
MOZ_MUST_USE bool emitEnd();
};
} // namespace frontend
} // namespace js
#endif /* frontend_ExpressionStatementEmitter_h */
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