DoWhileEmitter.h - mozsearch

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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_DoWhileEmitter_h

#define frontend_DoWhileEmitter_h

#include "mozilla/Attributes.h"

#include "mozilla/Maybe.h"

#include <stdint.h>

#include "frontend/BytecodeControlStructures.h"

namespace js {

namespace frontend {

struct BytecodeEmitter;

// Class for emitting bytecode for do-while loop.

//

// Usage: (check for the return value is omitted for simplicity)

//

//   `do body while (cond);`

//     DoWhileEmitter doWhile(this);

//     doWhile.emitBody(offset_of_do, offset_of_body);

//     emit(body);

//     doWhile.emitCond();

//     emit(cond);

//     doWhile.emitEnd();

//

class MOZ_STACK_CLASS DoWhileEmitter {

  BytecodeEmitter* bce_;

  mozilla::Maybe<LoopControl> loopInfo_;

#ifdef DEBUG

  // The state of this emitter.

//

  // +-------+ emitBody +------+ emitCond +------+ emitEnd  +-----+

  // | Start |--------->| Body |--------->| Cond |--------->| End |

  // +-------+          +------+          +------+          +-----+

  enum class State {

    // The initial state.

    Start,

    // After calling emitBody.

    Body,

    // After calling emitCond.

    Cond,

    // After calling emitEnd.

End

};

  State state_ = State::Start;

#endif

 public:

  explicit DoWhileEmitter(BytecodeEmitter* bce);

  // Parameters are the offset in the source code for each character below:

//

  //   do { ... } while ( x < 20 );

  //   ^  ^

  //   |  |

  //   |  bodyPos

  //   |

  //   doPos

  [[nodiscard]] bool emitBody(uint32_t doPos, uint32_t bodyPos);

  [[nodiscard]] bool emitCond();

  [[nodiscard]] bool emitEnd();

};

} /* namespace frontend */

} /* namespace js */

#endif /* frontend_DoWhileEmitter_h */