Differential D3143 Diff 14286 ps/trunk/libraries/source/spidermonkey/include-win32-debug/js/StableStringChars.h

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ps/trunk/libraries/source/spidermonkey/include-win32-debug/js/StableStringChars.h

				/* -- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -- */
				/* 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/. */

				/*
				* Safely access the contents of a string even as GC can cause the string's
				* contents to move around in memory.
				*/

				#ifndef js_StableStringChars_h
				#define js_StableStringChars_h

				#include "mozilla/Assertions.h" // MOZ_ASSERT
				#include "mozilla/Attributes.h" // MOZ_INIT_OUTSIDE_CTOR, MOZ_STACK_CLASS, MOZ_MUST_USE
				#include "mozilla/Maybe.h" // mozilla::Maybe
				#include "mozilla/Range.h" // mozilla::Range

				#include <stddef.h> // size_t
				#include <stdint.h> // uint8_t

				#include "jstypes.h" // JS_FRIEND_API

				#include "js/HeapAPI.h" // JS::shadow::String
				#include "js/RootingAPI.h" // JS::Handle, JS::Rooted
				#include "js/TypeDecls.h" // JSContext, JS::Latin1Char, JSString
				#include "js/Vector.h" // js::Vector

				class JSLinearString;

				namespace JS {

				MOZ_ALWAYS_INLINE size_t GetStringLength(JSString* s) {
				return reinterpret_cast<shadow::String*>(s)->length();
				}

				/**
				* This class provides safe access to a string's chars across a GC. Once
				* we allocate strings and chars in the nursery (bug 903519), this class
				* will have to make a copy of the string's chars if they are allocated
				* in the nursery, so it's best to avoid using this class unless you really
				* need it. It's usually more efficient to use the latin1Chars/twoByteChars
				* JSString methods and often the code can be rewritten so that only indexes
				* instead of char pointers are used in parts of the code that can GC.
				*/
				class MOZ_STACK_CLASS JS_FRIEND_API AutoStableStringChars final {
				/*
				* When copying string char, use this many bytes of inline storage. This is
				* chosen to allow the inline string types to be copied without allocating.
				* This is asserted in AutoStableStringChars::allocOwnChars.
				*/
				static const size_t InlineCapacity = 24;

				/* Ensure the string is kept alive while we're using its chars. */
				Rooted<JSString*> s_;
				union MOZ_INIT_OUTSIDE_CTOR {
				const char16_t* twoByteChars_;
				const Latin1Char* latin1Chars_;
				};
				mozilla::Maybe<js::Vector<uint8_t, InlineCapacity>> ownChars_;
				enum State { Uninitialized, Latin1, TwoByte };
				State state_;

				public:
				explicit AutoStableStringChars(JSContext* cx)
				: s_(cx), state_(Uninitialized) {}

				MOZ_MUST_USE bool init(JSContext* cx, JSString* s);

				/* Like init(), but Latin1 chars are inflated to TwoByte. */
				MOZ_MUST_USE bool initTwoByte(JSContext* cx, JSString* s);

				bool isLatin1() const { return state_ == Latin1; }
				bool isTwoByte() const { return state_ == TwoByte; }

				const Latin1Char* latin1Chars() const {
				MOZ_ASSERT(state_ == Latin1);
				return latin1Chars_;
				}
				const char16_t* twoByteChars() const {
				MOZ_ASSERT(state_ == TwoByte);
				return twoByteChars_;
				}

				mozilla::Range<const Latin1Char> latin1Range() const {
				MOZ_ASSERT(state_ == Latin1);
				return mozilla::Range<const Latin1Char>(latin1Chars_, GetStringLength(s_));
				}

				mozilla::Range<const char16_t> twoByteRange() const {
				MOZ_ASSERT(state_ == TwoByte);
				return mozilla::Range<const char16_t>(twoByteChars_, GetStringLength(s_));
				}

				/* If we own the chars, transfer ownership to the caller. */
				bool maybeGiveOwnershipToCaller() {
				MOZ_ASSERT(state_ != Uninitialized);
				if (!ownChars_.isSome() \|\| !ownChars_->extractRawBuffer()) {
				return false;
				}
				state_ = Uninitialized;
				ownChars_.reset();
				return true;
				}

				private:
				AutoStableStringChars(const AutoStableStringChars& other) = delete;
				void operator=(const AutoStableStringChars& other) = delete;

				bool baseIsInline(Handle<JSLinearString*> linearString);
				template <typename T>
				T* allocOwnChars(JSContext* cx, size_t count);
				bool copyLatin1Chars(JSContext* cx, Handle<JSLinearString*> linearString);
				bool copyTwoByteChars(JSContext* cx, Handle<JSLinearString*> linearString);
				bool copyAndInflateLatin1Chars(JSContext*,
				Handle<JSLinearString*> linearString);
				};

				} // namespace JS

				#endif /* js_StableStringChars_h */