/* -*- 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_AsyncEmitter_h
#define frontend_AsyncEmitter_h
#include "mozilla/Attributes.h" // MOZ_STACK_CLASS
#include "frontend/TryEmitter.h" // TryEmitter
namespace js {
namespace frontend {
struct BytecodeEmitter;
// Class for emitting Bytecode associated with the AsyncFunctionGenerator.
//
// Usage:
//
// For an async function, the params have to be handled separately,
// because the body may have pushed an additional var environment, changing
// the number of hops required to reach the |.generator| variable. In order
// to handle this, we can't reuse the same TryCatch emitter.
//
// Simple case - For a function without expression or destructuring
// parameters:
// `async function f(<params>) {<body>}`,
// AsyncEmitter ae(this);
//
// ae.prepareForParamsWithoutExpressionOrDestructuring();
// // Emit Params.
// ...
// ae.paramsEpilogue(); // We need to emit the epilogue before the extra
// VarScope emitExtraBodyVarScope();
//
// // Emit new scope
// ae.prepareForBody();
//
// // Emit body of the Function.
// ...
//
// ae.emitEndFunction();
//
// Complex case - For a function with expression or destructuring parameters:
// `async function f(<expression>) {<body>}`,
// AsyncEmitter ae(this);
//
// ae.prepareForParamsWithExpressionOrDestructuring();
//
// // Emit Params.
// ...
// ae.paramsEpilogue(); // We need to emit the epilogue before the extra
// // VarScope
// emitExtraBodyVarScope();
//
// // Emit new scope
// ae.prepareForBody();
//
// // Emit body of the Function.
// ...
//
// // The final yield is emitted in FunctionScriptEmitter::emitEndBody().
// ae.emitEndFunction();
//
//
// Async Module case - For a module with `await` in the top level:
// AsyncEmitter ae(this);
// ae.prepareForModule(); // prepareForModule is used to setup the generator
// // for the async module.
// switchToMain();
// ...
//
// // Emit new scope
// ae.prepareForBody();
//
// // Emit body of the Script.
//
// ae.emitEndModule();
//
class MOZ_STACK_CLASS AsyncEmitter {
private:
BytecodeEmitter* bce_;
// try-catch block for async function parameter and body.
mozilla::Maybe<TryEmitter> rejectTryCatch_;
#ifdef DEBUG
// The state of this emitter.
//
// +-------+
// | Start |-+
// +-------+ |
// |
// +----------+
// |
// | [Parameters with Expression or Destructuring]
// | prepareForParamsWithExpressionOrDestructuring +------------+
// +----------------------------------------------------| Parameters |-->+
// | +------------+ |
// | |
// | [Parameters Without Expression or Destructuring] |
// | prepareForParamsWithoutExpressionOrDestructuring +------------+ |
// +----------------------------------------------------| Parameters |-->+
// | +------------+ |
// | [Modules] |
// | prepareForModule +----------------+ |
// +-------------------->| ModulePrologue |--+ |
// +----------------+ | |
// | |
// | |
// +-----------------------------------------+ |
// | |
// | |
// V +------------+ paramsEpilogue |
// +<--------------------| PostParams |<---------------------------------+
// | +------------+
// |
// | [Script body]
// | prepareForBody +---------+
// +-------------------->| Body |--------+
// +---------+ | <emit script body>
// +----------------------------------------+
// |
// | [Functions]
// | emitEndFunction +-----+
// +--------------------->| End |
// | +-----+
// |
// | [Modules]
// | emitEndModule +-----+
// +--------------------->| End |
// +-----+
enum class State {
// The initial state.
Start,
Parameters,
ModulePrologue,
PostParams,
Body,
End,
};
State state_ = State::Start;
#endif
[[nodiscard]] bool emitRejectCatch();
[[nodiscard]] bool emitFinalYield();
public:
explicit AsyncEmitter(BytecodeEmitter* bce) : bce_(bce){};
[[nodiscard]] bool prepareForParamsWithoutExpressionOrDestructuring();
[[nodiscard]] bool prepareForParamsWithExpressionOrDestructuring();
[[nodiscard]] bool prepareForModule();
[[nodiscard]] bool emitParamsEpilogue();
[[nodiscard]] bool prepareForBody();
[[nodiscard]] bool emitEndFunction();
[[nodiscard]] bool emitEndModule();
};
} /* namespace frontend */
} /* namespace js */
#endif /* frontend_AsyncEmitter_h */
