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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_ForOfEmitter_h
+#define frontend_ForOfEmitter_h
+
+#include "mozilla/Attributes.h" // MOZ_STACK_CLASS
+#include "mozilla/Maybe.h" // mozilla::Maybe
+
+#include <stdint.h> // int32_t
+
+#include "frontend/ForOfLoopControl.h" // ForOfLoopControl
+#include "frontend/IteratorKind.h" // IteratorKind
+#include "frontend/SelfHostedIter.h" // SelfHostedIter
+#include "frontend/TDZCheckCache.h" // TDZCheckCache
+
+namespace js {
+namespace frontend {
+
+struct BytecodeEmitter;
+class EmitterScope;
+
+// Class for emitting bytecode for for-of loop.
+//
+// Usage: (check for the return value is omitted for simplicity)
+//
+// `for (init of iterated) body`
+// // headLexicalEmitterScope: lexical scope for init
+// ForOfEmitter forOf(this, headLexicalEmitterScope);
+// forOf.emitIterated();
+// emit(iterated);
+// forOf.emitInitialize(offset_of_for);
+// emit(init);
+// forOf.emitBody();
+// emit(body);
+// forOf.emitEnd(offset_of_iterated);
+//
+class MOZ_STACK_CLASS ForOfEmitter {
+ BytecodeEmitter* bce_;
+
+#ifdef DEBUG
+ // The stack depth before emitting IteratorNext code inside loop.
+ int32_t loopDepth_ = 0;
+#endif
+
+ SelfHostedIter selfHostedIter_;
+ IteratorKind iterKind_;
+
+ mozilla::Maybe<ForOfLoopControl> loopInfo_;
+
+ // The lexical scope to be freshened for each iteration.
+ // See the comment in `emitBody` for more details.
+ const EmitterScope* headLexicalEmitterScope_;
+
+ // Cache for the iterated value.
+ // (The cache for the iteration body is inside `loopInfo_`)
+ mozilla::Maybe<TDZCheckCache> tdzCacheForIteratedValue_;
+
+#ifdef DEBUG
+ // The state of this emitter.
+ //
+ // +-------+ emitIterated +----------+ emitInitialize +------------+
+ // | Start |------------->| Iterated |--------------->| Initialize |-+
+ // +-------+ +----------+ +------------+ |
+ // |
+ // +----------------------------------+
+ // |
+ // | emitBody +------+ emitEnd +-----+
+ // +----------| Body |--------->| End |
+ // +------+ +-----+
+ enum class State {
+ // The initial state.
+ Start,
+
+ // After calling emitIterated.
+ Iterated,
+
+ // After calling emitInitialize.
+ Initialize,
+
+ // After calling emitBody.
+ Body,
+
+ // After calling emitEnd.
+ End
+ };
+ State state_ = State::Start;
+#endif
+
+ public:
+ ForOfEmitter(BytecodeEmitter* bce,
+ const EmitterScope* headLexicalEmitterScope,
+ SelfHostedIter selfHostedIter, IteratorKind iterKind);
+
+ // The offset in the source code for each character below:
+ //
+ // for ( var x of obj ) { ... }
+ // ^ ^
+ // | |
+ // | iteratedPos
+ // |
+ // forPos
+ [[nodiscard]] bool emitIterated();
+ [[nodiscard]] bool emitInitialize(uint32_t forPos);
+ [[nodiscard]] bool emitBody();
+ [[nodiscard]] bool emitEnd(uint32_t iteratedPos);
+};
+
+} /* namespace frontend */
+} /* namespace js */
+
+#endif /* frontend_ForOfEmitter_h */