зеркало из https://github.com/mozilla/gecko-dev.git
85 строки
2.2 KiB
C++
85 строки
2.2 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/* vim:set ts=4 sw=4 sts=4 et cindent: */
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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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/* We would use std::max but MS makes it painful
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// windef.h defines min and max macros that we don't want
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// http://support.microsoft.com/kb/143208
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#ifdef _WIN32
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#define NOMINMAX
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#endif
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*/
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#include <stdlib.h>
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#include <string.h>
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#include "nsAlgorithm.h"
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/* This is a standard string builder like ones in Java
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or C#. It uses a doubling allocation strategy
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to grow when out of capacity.
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This does not use nsTArray because nsTArray starts
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growing by multiples of page size after it is the
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size of one page. We want to keep doubling in size
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so that we can continue to append at high speed even
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for large strings.
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Eventually, this should be templated for wide characters.
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*/
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namespace mozilla {
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class StringBuilder
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{
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public:
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StringBuilder() {
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mCapacity = 16;
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mLength = 0;
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mBuffer = static_cast<char*>(malloc(sizeof(char)*mCapacity));
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mBuffer[0] = '\0';
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}
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void Append(const char *s) {
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size_t newLength = strlen(s);
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EnsureCapacity(mLength + newLength+1);
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// copy the entire string including the null terminator
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memcpy(&mBuffer[mLength], s, newLength+1);
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mLength += newLength;
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}
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char *Buffer() {
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return mBuffer;
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}
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size_t Length() {
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return mLength;
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}
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size_t EnsureCapacity(size_t capacity) {
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if (capacity > mCapacity) {
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// make sure we at least double in size
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mCapacity = XPCOM_MAX(capacity, mCapacity*2);
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mBuffer = static_cast<char*>(realloc(mBuffer, mCapacity));
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mCapacity = moz_malloc_usable_size(mBuffer);
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}
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return mCapacity;
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}
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~StringBuilder()
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{
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free(mBuffer);
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}
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private:
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char *mBuffer;
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size_t mLength; // the length of the contained string not including the null terminator
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size_t mCapacity; // the total size of mBuffer
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};
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}
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