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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_ForOfLoopControl_h
#define frontend_ForOfLoopControl_h
#include "mozilla/Maybe.h" // mozilla::Maybe
#include <stdint.h> // int32_t, uint32_t
#include "frontend/BytecodeControlStructures.h" // NestableControl, LoopControl
#include "frontend/IteratorKind.h" // IteratorKind
#include "frontend/SelfHostedIter.h" // SelfHostedIter
#include "frontend/TryEmitter.h" // TryEmitter
#include "vm/CompletionKind.h" // CompletionKind
namespace js {
namespace frontend {
struct BytecodeEmitter;
class BytecodeOffset;
class EmitterScope;
class ForOfLoopControl : public LoopControl {
// The stack depth of the iterator.
int32_t iterDepth_;
// For-of loops, when throwing from non-iterator code (i.e. from the body
// or from evaluating the LHS of the loop condition), need to call
// IteratorClose. This is done by enclosing the body of the loop with
// try-catch and calling IteratorClose in the `catch` block.
//
// If IteratorClose itself throws, we must not re-call
// IteratorClose. Since non-local jumps like break and return call
// IteratorClose, whenever a non-local jump is emitted, we must
// prevent the catch block from catching any exception thrown from
// IteratorClose. We do this by wrapping the non-local jump in a
// ForOfIterClose try-note.
//
// for (x of y) {
// // Operations for iterator (IteratorNext etc) are outside of
// // try-block.
// try {
// ...
// if (...) {
// // Before non-local jump, close iterator.
// CloseIter(iter, CompletionKind::Return); // Covered by
// return; // trynote
// }
// ...
// } catch (e) {
// // When propagating an exception, we swallow any exceptions
// // thrown while closing the iterator.
// CloseIter(iter, CompletionKind::Throw);
// throw e;
// }
// }
mozilla::Maybe<TryEmitter> tryCatch_;
// Used to track if any yields were emitted between calls to to
// emitBeginCodeNeedingIteratorClose and emitEndCodeNeedingIteratorClose.
uint32_t numYieldsAtBeginCodeNeedingIterClose_;
SelfHostedIter selfHostedIter_;
IteratorKind iterKind_;
public:
ForOfLoopControl(BytecodeEmitter* bce, int32_t iterDepth,
SelfHostedIter selfHostedIter, IteratorKind iterKind);
[[nodiscard]] bool emitBeginCodeNeedingIteratorClose(BytecodeEmitter* bce);
[[nodiscard]] bool emitEndCodeNeedingIteratorClose(BytecodeEmitter* bce);
[[nodiscard]] bool emitIteratorCloseInInnermostScopeWithTryNote(
BytecodeEmitter* bce,
CompletionKind completionKind = CompletionKind::Normal);
[[nodiscard]] bool emitIteratorCloseInScope(
BytecodeEmitter* bce, EmitterScope& currentScope,
CompletionKind completionKind = CompletionKind::Normal);
[[nodiscard]] bool emitPrepareForNonLocalJumpFromScope(
BytecodeEmitter* bce, EmitterScope& currentScope, bool isTarget,
BytecodeOffset* tryNoteStart);
};
template <>
inline bool NestableControl::is<ForOfLoopControl>() const {
return kind_ == StatementKind::ForOfLoop;
}
} /* namespace frontend */
} /* namespace js */
#endif /* frontend_ForOfLoopControl_h */
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