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TryNoteKind.h
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TryNoteKind.h
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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 vm_TryNoteKind_h
#define vm_TryNoteKind_h
#include <stdint.h> // uint8_t
namespace js {
/*
* [SMDOC] Try Notes
*
* Trynotes are attached to regions that are involved with
* exception unwinding. They can be broken up into four categories:
*
* 1. Catch and Finally: Basic exception handling. A Catch trynote
* covers the range of the associated try. A Finally trynote covers
* the try and the catch.
*
* 2. ForIn and Destructuring: These operations create an iterator
* which must be cleaned up (by calling IteratorClose) during
* exception unwinding.
*
* 3. ForOf and ForOfIterclose: For-of loops handle unwinding using
* catch blocks. These trynotes are used for for-of breaks/returns,
* which create regions that are lexically within a for-of block,
* but logically outside of it. See TryNoteIter::settle for more
* details.
*
* 4. Loop: This represents normal for/while/do-while loops. It is
* unnecessary for exception unwinding, but storing the boundaries
* of loops here is helpful for heuristics that need to know
* whether a given op is inside a loop.
*/
enum class TryNoteKind : uint8_t {
Catch,
Finally,
ForIn,
Destructuring,
ForOf,
ForOfIterClose,
Loop
};
} // namespace js
#endif /* vm_TryNoteKind_h */