michael@0: /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
michael@0: /* vim:set ts=4 sw=4 sts=4 et cindent: */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: /* We would use std::max but MS makes it painful
michael@0: // windef.h defines min and max macros that we don't want
michael@0: // http://support.microsoft.com/kb/143208
michael@0: #ifdef _WIN32
michael@0: #define NOMINMAX
michael@0: #endif
michael@0: */
michael@0: 
michael@0: #include <stdlib.h>
michael@0: #include <string.h>
michael@0: #include "nsAlgorithm.h"
michael@0: 
michael@0: /* This is a standard string builder like ones in Java
michael@0:    or C#. It uses a doubling allocation strategy
michael@0:    to grow when out of capacity.
michael@0: 
michael@0:    This does not use nsTArray because nsTArray starts
michael@0:    growing by multiples of page size after it is the
michael@0:    size of one page. We want to keep doubling in size
michael@0:    so that we can continue to append at high speed even
michael@0:    for large strings.
michael@0: 
michael@0:    Eventually, this should be templated for wide characters.
michael@0: 
michael@0:  */
michael@0: 
michael@0: namespace mozilla {
michael@0: 
michael@0: class StringBuilder
michael@0: {
michael@0: public:
michael@0:     StringBuilder() {
michael@0:         mCapacity = 16;
michael@0:         mLength = 0;
michael@0:         mBuffer = static_cast<char*>(malloc(sizeof(char)*mCapacity));
michael@0:         mBuffer[0] = '\0';
michael@0:     }
michael@0: 
michael@0:     void Append(const char *s) {
michael@0:         size_t newLength = strlen(s);
michael@0: 
michael@0:         EnsureCapacity(mLength + newLength+1);
michael@0: 
michael@0:         // copy the entire string including the null terminator
michael@0:         memcpy(&mBuffer[mLength], s, newLength+1);
michael@0:         mLength += newLength;
michael@0:     }
michael@0: 
michael@0:     char *Buffer() {
michael@0:         return mBuffer;
michael@0:     }
michael@0: 
michael@0:     size_t Length() {
michael@0:         return mLength;
michael@0:     }
michael@0: 
michael@0:     size_t EnsureCapacity(size_t capacity) {
michael@0:         if (capacity > mCapacity) {
michael@0:             // make sure we at least double in size
michael@0:             mCapacity = XPCOM_MAX(capacity, mCapacity*2);
michael@0:             mBuffer = static_cast<char*>(realloc(mBuffer, mCapacity));
michael@0:             mCapacity = moz_malloc_usable_size(mBuffer);
michael@0:         }
michael@0:         return mCapacity;
michael@0:     }
michael@0: 
michael@0:     ~StringBuilder()
michael@0:     {
michael@0:         free(mBuffer);
michael@0:     }
michael@0: 
michael@0: private:
michael@0:     char *mBuffer;
michael@0:     size_t mLength; // the length of the contained string not including the null terminator
michael@0:     size_t mCapacity; // the total size of mBuffer
michael@0: };
michael@0: 
michael@0: }