зеркало из https://github.com/mozilla/gecko-dev.git
651 строка
19 KiB
C++
651 строка
19 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim:set ts=2 sw=2 sts=2 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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#include <stdlib.h>
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#include "nsScannerString.h"
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/**
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* nsScannerBufferList
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*/
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#define MAX_CAPACITY ((UINT32_MAX / sizeof(char16_t)) - \
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(sizeof(Buffer) + sizeof(char16_t)))
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nsScannerBufferList::Buffer*
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nsScannerBufferList::AllocBufferFromString( const nsAString& aString )
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{
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uint32_t len = aString.Length();
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Buffer* buf = AllocBuffer(len);
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if (buf)
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{
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nsAString::const_iterator source;
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aString.BeginReading(source);
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nsCharTraits<char16_t>::copy(buf->DataStart(), source.get(), len);
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}
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return buf;
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}
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nsScannerBufferList::Buffer*
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nsScannerBufferList::AllocBuffer( uint32_t capacity )
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{
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if (capacity > MAX_CAPACITY)
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return nullptr;
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void* ptr = malloc(sizeof(Buffer) + (capacity + 1) * sizeof(char16_t));
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if (!ptr)
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return nullptr;
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Buffer* buf = new (ptr) Buffer();
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buf->mUsageCount = 0;
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buf->mDataEnd = buf->DataStart() + capacity;
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// XXX null terminate. this shouldn't be required, but we do it because
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// nsScanner erroneously thinks it can dereference DataEnd :-(
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*buf->mDataEnd = char16_t(0);
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return buf;
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}
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void
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nsScannerBufferList::ReleaseAll()
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{
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while (!mBuffers.isEmpty())
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{
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Buffer* node = mBuffers.popFirst();
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//printf(">>> freeing buffer @%p\n", node);
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free(node);
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}
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}
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void
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nsScannerBufferList::SplitBuffer( const Position& pos )
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{
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// splitting to the right keeps the work string and any extant token
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// pointing to and holding a reference count on the same buffer.
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Buffer* bufferToSplit = pos.mBuffer;
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NS_ASSERTION(bufferToSplit, "null pointer");
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uint32_t splitOffset = pos.mPosition - bufferToSplit->DataStart();
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NS_ASSERTION(pos.mPosition >= bufferToSplit->DataStart() &&
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splitOffset <= bufferToSplit->DataLength(),
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"split offset is outside buffer");
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uint32_t len = bufferToSplit->DataLength() - splitOffset;
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Buffer* new_buffer = AllocBuffer(len);
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if (new_buffer)
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{
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nsCharTraits<char16_t>::copy(new_buffer->DataStart(),
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bufferToSplit->DataStart() + splitOffset,
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len);
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InsertAfter(new_buffer, bufferToSplit);
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bufferToSplit->SetDataLength(splitOffset);
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}
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}
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void
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nsScannerBufferList::DiscardUnreferencedPrefix( Buffer* aBuf )
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{
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if (aBuf == Head())
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{
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while (!mBuffers.isEmpty() && !Head()->IsInUse())
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{
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Buffer* buffer = Head();
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buffer->remove();
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free(buffer);
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}
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}
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}
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size_t
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nsScannerBufferList::Position::Distance( const Position& aStart, const Position& aEnd )
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{
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size_t result = 0;
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if (aStart.mBuffer == aEnd.mBuffer)
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{
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result = aEnd.mPosition - aStart.mPosition;
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}
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else
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{
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result = aStart.mBuffer->DataEnd() - aStart.mPosition;
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for (Buffer* b = aStart.mBuffer->Next(); b != aEnd.mBuffer; b = b->Next())
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result += b->DataLength();
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result += aEnd.mPosition - aEnd.mBuffer->DataStart();
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}
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return result;
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}
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/**
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* nsScannerSubstring
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*/
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nsScannerSubstring::nsScannerSubstring()
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: mStart(nullptr, nullptr)
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, mEnd(nullptr, nullptr)
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, mBufferList(nullptr)
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, mLength(0)
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, mIsDirty(true)
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{
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}
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nsScannerSubstring::nsScannerSubstring( const nsAString& s )
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: mBufferList(nullptr)
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, mIsDirty(true)
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{
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Rebind(s);
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}
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nsScannerSubstring::~nsScannerSubstring()
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{
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release_ownership_of_buffer_list();
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}
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int32_t
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nsScannerSubstring::CountChar( char16_t c ) const
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{
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/*
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re-write this to use a counting sink
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*/
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size_type result = 0;
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size_type lengthToExamine = Length();
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nsScannerIterator iter;
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for ( BeginReading(iter); ; )
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{
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int32_t lengthToExamineInThisFragment = iter.size_forward();
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const char16_t* fromBegin = iter.get();
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result += size_type(NS_COUNT(fromBegin, fromBegin+lengthToExamineInThisFragment, c));
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if ( !(lengthToExamine -= lengthToExamineInThisFragment) )
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return result;
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iter.advance(lengthToExamineInThisFragment);
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}
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// never reached; quiets warnings
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return 0;
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}
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void
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nsScannerSubstring::Rebind( const nsScannerSubstring& aString,
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const nsScannerIterator& aStart,
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const nsScannerIterator& aEnd )
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{
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// allow for the case where &aString == this
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aString.acquire_ownership_of_buffer_list();
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release_ownership_of_buffer_list();
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mStart = aStart;
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mEnd = aEnd;
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mBufferList = aString.mBufferList;
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mLength = Distance(aStart, aEnd);
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mIsDirty = true;
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}
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void
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nsScannerSubstring::Rebind( const nsAString& aString )
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{
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release_ownership_of_buffer_list();
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mBufferList = new nsScannerBufferList(AllocBufferFromString(aString));
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mIsDirty = true;
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init_range_from_buffer_list();
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acquire_ownership_of_buffer_list();
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}
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const nsSubstring&
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nsScannerSubstring::AsString() const
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{
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if (mIsDirty)
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{
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nsScannerSubstring* mutable_this = const_cast<nsScannerSubstring*>(this);
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if (mStart.mBuffer == mEnd.mBuffer) {
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// We only have a single fragment to deal with, so just return it
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// as a substring.
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mutable_this->mFlattenedRep.Rebind(mStart.mPosition, mEnd.mPosition);
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} else {
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// Otherwise, we need to copy the data into a flattened buffer.
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nsScannerIterator start, end;
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CopyUnicodeTo(BeginReading(start), EndReading(end), mutable_this->mFlattenedRep);
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}
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mutable_this->mIsDirty = false;
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}
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return mFlattenedRep;
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}
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nsScannerIterator&
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nsScannerSubstring::BeginReading( nsScannerIterator& iter ) const
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{
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iter.mOwner = this;
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iter.mFragment.mBuffer = mStart.mBuffer;
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iter.mFragment.mFragmentStart = mStart.mPosition;
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if (mStart.mBuffer == mEnd.mBuffer)
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iter.mFragment.mFragmentEnd = mEnd.mPosition;
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else
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iter.mFragment.mFragmentEnd = mStart.mBuffer->DataEnd();
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iter.mPosition = mStart.mPosition;
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iter.normalize_forward();
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return iter;
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}
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nsScannerIterator&
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nsScannerSubstring::EndReading( nsScannerIterator& iter ) const
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{
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iter.mOwner = this;
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iter.mFragment.mBuffer = mEnd.mBuffer;
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iter.mFragment.mFragmentEnd = mEnd.mPosition;
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if (mStart.mBuffer == mEnd.mBuffer)
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iter.mFragment.mFragmentStart = mStart.mPosition;
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else
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iter.mFragment.mFragmentStart = mEnd.mBuffer->DataStart();
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iter.mPosition = mEnd.mPosition;
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// must not |normalize_backward| as that would likely invalidate tests like |while ( first != last )|
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return iter;
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}
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bool
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nsScannerSubstring::GetNextFragment( nsScannerFragment& frag ) const
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{
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// check to see if we are at the end of the buffer list
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if (frag.mBuffer == mEnd.mBuffer)
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return false;
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frag.mBuffer = frag.mBuffer->getNext();
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if (frag.mBuffer == mStart.mBuffer)
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frag.mFragmentStart = mStart.mPosition;
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else
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frag.mFragmentStart = frag.mBuffer->DataStart();
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if (frag.mBuffer == mEnd.mBuffer)
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frag.mFragmentEnd = mEnd.mPosition;
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else
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frag.mFragmentEnd = frag.mBuffer->DataEnd();
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return true;
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}
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bool
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nsScannerSubstring::GetPrevFragment( nsScannerFragment& frag ) const
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{
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// check to see if we are at the beginning of the buffer list
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if (frag.mBuffer == mStart.mBuffer)
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return false;
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frag.mBuffer = frag.mBuffer->getPrevious();
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if (frag.mBuffer == mStart.mBuffer)
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frag.mFragmentStart = mStart.mPosition;
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else
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frag.mFragmentStart = frag.mBuffer->DataStart();
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if (frag.mBuffer == mEnd.mBuffer)
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frag.mFragmentEnd = mEnd.mPosition;
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else
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frag.mFragmentEnd = frag.mBuffer->DataEnd();
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return true;
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}
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/**
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* nsScannerString
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*/
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nsScannerString::nsScannerString( Buffer* aBuf )
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{
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mBufferList = new nsScannerBufferList(aBuf);
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init_range_from_buffer_list();
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acquire_ownership_of_buffer_list();
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}
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void
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nsScannerString::AppendBuffer( Buffer* aBuf )
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{
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mBufferList->Append(aBuf);
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mLength += aBuf->DataLength();
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mEnd.mBuffer = aBuf;
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mEnd.mPosition = aBuf->DataEnd();
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mIsDirty = true;
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}
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void
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nsScannerString::DiscardPrefix( const nsScannerIterator& aIter )
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{
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Position old_start(mStart);
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mStart = aIter;
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mLength -= Position::Distance(old_start, mStart);
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mStart.mBuffer->IncrementUsageCount();
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old_start.mBuffer->DecrementUsageCount();
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mBufferList->DiscardUnreferencedPrefix(old_start.mBuffer);
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mIsDirty = true;
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}
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void
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nsScannerString::UngetReadable( const nsAString& aReadable, const nsScannerIterator& aInsertPoint )
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/*
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* Warning: this routine manipulates the shared buffer list in an unexpected way.
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* The original design did not really allow for insertions, but this call promises
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* that if called for a point after the end of all extant token strings, that no token string
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* or the work string will be invalidated.
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*
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* This routine is protected because it is the responsibility of the derived class to keep those promises.
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*/
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{
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Position insertPos(aInsertPoint);
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mBufferList->SplitBuffer(insertPos);
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// splitting to the right keeps the work string and any extant token pointing to and
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// holding a reference count on the same buffer
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Buffer* new_buffer = AllocBufferFromString(aReadable);
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// make a new buffer with all the data to insert...
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// BULLSHIT ALERT: we may have empty space to re-use in the split buffer, measure the cost
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// of this and decide if we should do the work to fill it
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Buffer* buffer_to_split = insertPos.mBuffer;
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mBufferList->InsertAfter(new_buffer, buffer_to_split);
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mLength += aReadable.Length();
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mEnd.mBuffer = mBufferList->Tail();
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mEnd.mPosition = mEnd.mBuffer->DataEnd();
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mIsDirty = true;
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}
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void
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nsScannerString::ReplaceCharacter(nsScannerIterator& aPosition, char16_t aChar)
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{
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// XXX Casting a const to non-const. Unless the base class
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// provides support for writing iterators, this is the best
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// that can be done.
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char16_t* pos = const_cast<char16_t*>(aPosition.get());
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*pos = aChar;
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mIsDirty = true;
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}
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/**
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* nsScannerSharedSubstring
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*/
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void
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nsScannerSharedSubstring::Rebind(const nsScannerIterator &aStart,
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const nsScannerIterator &aEnd)
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{
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// If the start and end positions are inside the same buffer, we must
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// acquire ownership of the buffer. If not, we can optimize by not holding
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// onto it.
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Buffer *buffer = const_cast<Buffer*>(aStart.buffer());
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bool sameBuffer = buffer == aEnd.buffer();
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nsScannerBufferList *bufferList;
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if (sameBuffer) {
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bufferList = aStart.mOwner->mBufferList;
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bufferList->AddRef();
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buffer->IncrementUsageCount();
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}
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if (mBufferList)
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ReleaseBuffer();
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if (sameBuffer) {
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mBuffer = buffer;
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mBufferList = bufferList;
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mString.Rebind(aStart.mPosition, aEnd.mPosition);
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} else {
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mBuffer = nullptr;
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mBufferList = nullptr;
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CopyUnicodeTo(aStart, aEnd, mString);
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}
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}
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void
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nsScannerSharedSubstring::ReleaseBuffer()
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{
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NS_ASSERTION(mBufferList, "Should only be called with non-null mBufferList");
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mBuffer->DecrementUsageCount();
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mBufferList->DiscardUnreferencedPrefix(mBuffer);
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mBufferList->Release();
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}
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void
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nsScannerSharedSubstring::MakeMutable()
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{
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nsString temp(mString); // this will force a copy of the data
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mString.Assign(temp); // mString will now share the just-allocated buffer
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ReleaseBuffer();
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mBuffer = nullptr;
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mBufferList = nullptr;
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}
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/**
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* utils -- based on code from nsReadableUtils.cpp
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*/
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// private helper function
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static inline
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nsAString::iterator&
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copy_multifragment_string( nsScannerIterator& first, const nsScannerIterator& last, nsAString::iterator& result )
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{
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typedef nsCharSourceTraits<nsScannerIterator> source_traits;
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typedef nsCharSinkTraits<nsAString::iterator> sink_traits;
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while ( first != last )
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{
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uint32_t distance = source_traits::readable_distance(first, last);
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sink_traits::write(result, source_traits::read(first), distance);
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NS_ASSERTION(distance > 0, "|copy_multifragment_string| will never terminate");
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source_traits::advance(first, distance);
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}
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return result;
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}
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bool
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CopyUnicodeTo( const nsScannerIterator& aSrcStart,
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const nsScannerIterator& aSrcEnd,
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nsAString& aDest )
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{
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nsAString::iterator writer;
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if (!aDest.SetLength(Distance(aSrcStart, aSrcEnd), mozilla::fallible)) {
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aDest.Truncate();
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return false; // out of memory
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}
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aDest.BeginWriting(writer);
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nsScannerIterator fromBegin(aSrcStart);
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copy_multifragment_string(fromBegin, aSrcEnd, writer);
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return true;
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}
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bool
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AppendUnicodeTo( const nsScannerIterator& aSrcStart,
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const nsScannerIterator& aSrcEnd,
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nsScannerSharedSubstring& aDest )
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{
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// Check whether we can just create a dependent string.
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if (aDest.str().IsEmpty()) {
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// We can just make |aDest| point to the buffer.
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// This will take care of copying if the buffer spans fragments.
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aDest.Rebind(aSrcStart, aSrcEnd);
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return true;
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}
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// The dest string is not empty, so it can't be a dependent substring.
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return AppendUnicodeTo(aSrcStart, aSrcEnd, aDest.writable());
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}
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bool
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AppendUnicodeTo( const nsScannerIterator& aSrcStart,
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const nsScannerIterator& aSrcEnd,
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nsAString& aDest )
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{
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nsAString::iterator writer;
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uint32_t oldLength = aDest.Length();
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if (!aDest.SetLength(oldLength + Distance(aSrcStart, aSrcEnd), mozilla::fallible))
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return false; // out of memory
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aDest.BeginWriting(writer).advance(oldLength);
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nsScannerIterator fromBegin(aSrcStart);
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copy_multifragment_string(fromBegin, aSrcEnd, writer);
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return true;
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}
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bool
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FindCharInReadable( char16_t aChar,
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nsScannerIterator& aSearchStart,
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const nsScannerIterator& aSearchEnd )
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{
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while ( aSearchStart != aSearchEnd )
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{
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int32_t fragmentLength;
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if ( SameFragment(aSearchStart, aSearchEnd) )
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fragmentLength = aSearchEnd.get() - aSearchStart.get();
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else
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fragmentLength = aSearchStart.size_forward();
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const char16_t* charFoundAt = nsCharTraits<char16_t>::find(aSearchStart.get(), fragmentLength, aChar);
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if ( charFoundAt ) {
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aSearchStart.advance( charFoundAt - aSearchStart.get() );
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return true;
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}
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aSearchStart.advance(fragmentLength);
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}
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return false;
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}
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bool
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FindInReadable( const nsAString& aPattern,
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nsScannerIterator& aSearchStart,
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nsScannerIterator& aSearchEnd,
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const nsStringComparator& compare )
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{
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bool found_it = false;
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// only bother searching at all if we're given a non-empty range to search
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if ( aSearchStart != aSearchEnd )
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{
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nsAString::const_iterator aPatternStart, aPatternEnd;
|
|
aPattern.BeginReading(aPatternStart);
|
|
aPattern.EndReading(aPatternEnd);
|
|
|
|
// outer loop keeps searching till we find it or run out of string to search
|
|
while ( !found_it )
|
|
{
|
|
// fast inner loop (that's what it's called, not what it is) looks for a potential match
|
|
while ( aSearchStart != aSearchEnd &&
|
|
compare(aPatternStart.get(), aSearchStart.get(), 1, 1) )
|
|
++aSearchStart;
|
|
|
|
// if we broke out of the `fast' loop because we're out of string ... we're done: no match
|
|
if ( aSearchStart == aSearchEnd )
|
|
break;
|
|
|
|
// otherwise, we're at a potential match, let's see if we really hit one
|
|
nsAString::const_iterator testPattern(aPatternStart);
|
|
nsScannerIterator testSearch(aSearchStart);
|
|
|
|
// slow inner loop verifies the potential match (found by the `fast' loop) at the current position
|
|
for(;;)
|
|
{
|
|
// we already compared the first character in the outer loop,
|
|
// so we'll advance before the next comparison
|
|
++testPattern;
|
|
++testSearch;
|
|
|
|
// if we verified all the way to the end of the pattern, then we found it!
|
|
if ( testPattern == aPatternEnd )
|
|
{
|
|
found_it = true;
|
|
aSearchEnd = testSearch; // return the exact found range through the parameters
|
|
break;
|
|
}
|
|
|
|
// if we got to end of the string we're searching before we hit the end of the
|
|
// pattern, we'll never find what we're looking for
|
|
if ( testSearch == aSearchEnd )
|
|
{
|
|
aSearchStart = aSearchEnd;
|
|
break;
|
|
}
|
|
|
|
// else if we mismatched ... it's time to advance to the next search position
|
|
// and get back into the `fast' loop
|
|
if ( compare(testPattern.get(), testSearch.get(), 1, 1) )
|
|
{
|
|
++aSearchStart;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return found_it;
|
|
}
|
|
|
|
/**
|
|
* This implementation is simple, but does too much work.
|
|
* It searches the entire string from left to right, and returns the last match found, if any.
|
|
* This implementation will be replaced when I get |reverse_iterator|s working.
|
|
*/
|
|
bool
|
|
RFindInReadable( const nsAString& aPattern,
|
|
nsScannerIterator& aSearchStart,
|
|
nsScannerIterator& aSearchEnd,
|
|
const nsStringComparator& aComparator )
|
|
{
|
|
bool found_it = false;
|
|
|
|
nsScannerIterator savedSearchEnd(aSearchEnd);
|
|
nsScannerIterator searchStart(aSearchStart), searchEnd(aSearchEnd);
|
|
|
|
while ( searchStart != searchEnd )
|
|
{
|
|
if ( FindInReadable(aPattern, searchStart, searchEnd, aComparator) )
|
|
{
|
|
found_it = true;
|
|
|
|
// this is the best match so far, so remember it
|
|
aSearchStart = searchStart;
|
|
aSearchEnd = searchEnd;
|
|
|
|
// ...and get ready to search some more
|
|
// (it's tempting to set |searchStart=searchEnd| ... but that misses overlapping patterns)
|
|
++searchStart;
|
|
searchEnd = savedSearchEnd;
|
|
}
|
|
}
|
|
|
|
// if we never found it, return an empty range
|
|
if ( !found_it )
|
|
aSearchStart = aSearchEnd;
|
|
|
|
return found_it;
|
|
}
|