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f4d91001fe
This adds an extension to ArenaAllocator that provides strdup-like functionality for various string types. MozReview-Commit-ID: 87SHTs6flHY
95 lines
2.8 KiB
C++
95 lines
2.8 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_ArenaAllocatorExtensions_h
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#define mozilla_ArenaAllocatorExtensions_h
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#include "mozilla/ArenaAllocator.h"
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#include "mozilla/CheckedInt.h"
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#include "nsAString.h"
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/**
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* Extensions to the ArenaAllocator class.
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*/
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namespace mozilla {
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namespace detail {
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template<typename T, size_t ArenaSize, size_t Alignment>
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T* DuplicateString(const T* aSrc, const CheckedInt<size_t>& aLen,
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ArenaAllocator<ArenaSize, Alignment>& aArena);
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} // namespace detail
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/**
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* Makes an arena allocated null-terminated copy of the source string. The
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* source string must be null-terminated.
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*
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* @param aSrc String to copy.
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* @param aArena The arena to allocate the string copy out of.
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* @return An arena allocated null-terminated string.
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*/
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template<size_t ArenaSize, size_t Alignment>
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char* ArenaStrdup(const char* aStr,
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ArenaAllocator<ArenaSize, Alignment>& aArena)
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{
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return detail::DuplicateString(aStr, strlen(aStr), aArena);
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}
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/**
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* Makes an arena allocated null-terminated copy of the source string.
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*
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* @param aSrc String to copy.
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* @param aArena The arena to allocate the string copy out of.
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* @return An arena allocated null-terminated string.
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*/
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template<size_t ArenaSize, size_t Alignment>
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nsAString::char_type* ArenaStrdup(
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const nsAString& aStr, ArenaAllocator<ArenaSize, Alignment>& aArena)
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{
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return detail::DuplicateString(aStr.BeginReading(), aStr.Length(), aArena);
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}
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/**
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* Makes an arena allocated null-terminated copy of the source string.
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*
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* @param aSrc String to copy.
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* @param aArena The arena to allocate the string copy out of.
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* @return An arena allocated null-terminated string.
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*/
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template<size_t ArenaSize, size_t Alignment>
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nsACString::char_type* ArenaStrdup(
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const nsACString& aStr, ArenaAllocator<ArenaSize, Alignment>& aArena)
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{
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return detail::DuplicateString(aStr.BeginReading(), aStr.Length(), aArena);
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}
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/**
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* Copies the source string and adds a null terminator. Source string does not
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* have to be null terminated.
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*/
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template<typename T, size_t ArenaSize, size_t Alignment>
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T* detail::DuplicateString(const T* aSrc, const CheckedInt<size_t>& aLen,
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ArenaAllocator<ArenaSize, Alignment>& aArena)
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{
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const auto byteLen = (aLen + 1) * sizeof(T);
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if (!byteLen.isValid()) {
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return nullptr;
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}
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T* p = static_cast<T*>(aArena.Allocate(byteLen.value(), mozilla::fallible));
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if (p) {
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memcpy(p, aSrc, byteLen.value() - sizeof(T));
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p[aLen.value()] = T(0);
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}
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return p;
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}
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} // namespace mozilla
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#endif // mozilla_ArenaAllocatorExtensions_h
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