forked from mirrors/gecko-dev
54fd961a29
There's no use case for stateful comparators, so they can be just plain function pointers. This is used in some hot places like CSS selector matching. Differential Revision: https://phabricator.services.mozilla.com/D77084
578 lines
17 KiB
C++
578 lines
17 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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#include "mozilla/CheckedInt.h"
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/**
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* nsScannerBufferList
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*/
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#define MAX_CAPACITY \
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((UINT32_MAX / sizeof(char16_t)) - (sizeof(Buffer) + sizeof(char16_t)))
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nsScannerBufferList::Buffer* nsScannerBufferList::AllocBufferFromString(
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const nsAString& aString) {
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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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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* nsScannerBufferList::AllocBuffer(
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uint32_t capacity) {
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if (capacity > MAX_CAPACITY) return nullptr;
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void* ptr = malloc(sizeof(Buffer) + (capacity + 1) * sizeof(char16_t));
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if (!ptr) 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 nsScannerBufferList::ReleaseAll() {
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while (!mBuffers.isEmpty()) {
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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 nsScannerBufferList::SplitBuffer(const Position& pos) {
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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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nsCharTraits<char16_t>::copy(new_buffer->DataStart(),
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bufferToSplit->DataStart() + splitOffset, 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 nsScannerBufferList::DiscardUnreferencedPrefix(Buffer* aBuf) {
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if (aBuf == Head()) {
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while (!mBuffers.isEmpty() && !Head()->IsInUse()) {
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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 nsScannerBufferList::Position::Distance(const Position& aStart,
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const Position& aEnd) {
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size_t result = 0;
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if (aStart.mBuffer == aEnd.mBuffer) {
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result = aEnd.mPosition - aStart.mPosition;
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} else {
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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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nsScannerSubstring::nsScannerSubstring(const nsAString& s)
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: mBufferList(nullptr), mIsDirty(true) {
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Rebind(s);
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}
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nsScannerSubstring::~nsScannerSubstring() {
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release_ownership_of_buffer_list();
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}
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int32_t nsScannerSubstring::CountChar(char16_t c) const {
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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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int32_t lengthToExamineInThisFragment = iter.size_forward();
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const char16_t* fromBegin = iter.get();
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result += size_type(
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NS_COUNT(fromBegin, fromBegin + lengthToExamineInThisFragment, c));
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if (!(lengthToExamine -= lengthToExamineInThisFragment)) 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 nsScannerSubstring::Rebind(const nsScannerSubstring& aString,
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const nsScannerIterator& aStart,
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const nsScannerIterator& aEnd) {
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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 nsScannerSubstring::Rebind(const nsAString& aString) {
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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 nsAString& nsScannerSubstring::AsString() const {
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if (mIsDirty) {
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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),
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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& nsScannerSubstring::BeginReading(
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nsScannerIterator& iter) const {
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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& nsScannerSubstring::EndReading(
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nsScannerIterator& iter) const {
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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
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// |while ( first != last )|
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return iter;
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}
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bool nsScannerSubstring::GetNextFragment(nsScannerFragment& frag) const {
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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) 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 nsScannerSubstring::GetPrevFragment(nsScannerFragment& frag) const {
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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) 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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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 nsScannerString::AppendBuffer(Buffer* aBuf) {
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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 nsScannerString::DiscardPrefix(const nsScannerIterator& aIter) {
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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 nsScannerString::UngetReadable(const nsAString& aReadable,
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const nsScannerIterator& aInsertPoint)
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/*
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* Warning: this routine manipulates the shared buffer list in an
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* unexpected way. The original design did not really allow for
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* insertions, but this call promises that if called for a point after the
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* end of all extant token strings, that no token string or the work string
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* will be invalidated.
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*
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* This routine is protected because it is the responsibility of the
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* 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
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// pointing to and 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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// ALERT: we may have empty space to re-use in the split buffer,
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// measure the cost of this and decide if we should do the work to fill
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// 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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/**
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* nsScannerSharedSubstring
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*/
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void nsScannerSharedSubstring::Rebind(const nsScannerIterator& aStart,
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const nsScannerIterator& aEnd) {
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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) 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 nsScannerSharedSubstring::ReleaseBuffer() {
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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 nsScannerSharedSubstring::MakeMutable() {
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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 nsAString::iterator& copy_multifragment_string(
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nsScannerIterator& first, const nsScannerIterator& last,
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nsAString::iterator& result) {
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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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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,
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"|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 CopyUnicodeTo(const nsScannerIterator& aSrcStart,
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const nsScannerIterator& aSrcEnd, nsAString& aDest) {
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mozilla::CheckedInt<nsAString::size_type> distance(
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Distance(aSrcStart, aSrcEnd));
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if (!distance.isValid()) {
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return false; // overflow detected
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}
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if (!aDest.SetLength(distance.value(), 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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auto writer = aDest.BeginWriting();
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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 AppendUnicodeTo(const nsScannerIterator& aSrcStart,
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const nsScannerIterator& aSrcEnd,
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nsScannerSharedSubstring& aDest) {
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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 AppendUnicodeTo(const nsScannerIterator& aSrcStart,
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const nsScannerIterator& aSrcEnd, nsAString& aDest) {
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const nsAString::size_type oldLength = aDest.Length();
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mozilla::CheckedInt<nsAString::size_type> newLen(
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Distance(aSrcStart, aSrcEnd));
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newLen += oldLength;
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if (!newLen.isValid()) {
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return false; // overflow detected
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}
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if (!aDest.SetLength(newLen.value(), mozilla::fallible))
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return false; // out of memory
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auto writer = aDest.BeginWriting();
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std::advance(writer, 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 FindCharInReadable(char16_t aChar, nsScannerIterator& aSearchStart,
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const nsScannerIterator& aSearchEnd) {
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while (aSearchStart != aSearchEnd) {
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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 =
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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 FindInReadable(const nsAString& aPattern, nsScannerIterator& aSearchStart,
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nsScannerIterator& aSearchEnd,
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const nsStringComparator compare) {
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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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nsAString::const_iterator aPatternStart, aPatternEnd;
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aPattern.BeginReading(aPatternStart);
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aPattern.EndReading(aPatternEnd);
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// outer loop keeps searching till we find it or run out of string to search
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while (!found_it) {
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// fast inner loop (that's what it's called, not what it is) looks for a
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// potential match
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while (aSearchStart != aSearchEnd &&
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compare(aPatternStart.get(), aSearchStart.get(), 1, 1))
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++aSearchStart;
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// if we broke out of the `fast' loop because we're out of string ...
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// we're done: no match
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if (aSearchStart == aSearchEnd) break;
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// otherwise, we're at a potential match, let's see if we really hit one
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nsAString::const_iterator testPattern(aPatternStart);
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nsScannerIterator testSearch(aSearchStart);
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// slow inner loop verifies the potential match (found by the `fast' loop)
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// at the current position
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for (;;) {
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// we already compared the first character in the outer loop,
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// so we'll advance before the next comparison
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++testPattern;
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++testSearch;
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// if we verified all the way to the end of the pattern, then we found
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// it!
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if (testPattern == aPatternEnd) {
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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;
|
|
}
|