diff options
Diffstat (limited to '')
| -rw-r--r-- | parser/htmlparser/nsScannerString.cpp | 379 |
1 files changed, 379 insertions, 0 deletions
diff --git a/parser/htmlparser/nsScannerString.cpp b/parser/htmlparser/nsScannerString.cpp new file mode 100644 index 0000000000..2c7f09cfdd --- /dev/null +++ b/parser/htmlparser/nsScannerString.cpp @@ -0,0 +1,379 @@ +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim:set ts=2 sw=2 sts=2 et cindent: */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#include <stdlib.h> +#include "nsScannerString.h" +#include "mozilla/CheckedInt.h" + +/** + * nsScannerBufferList + */ + +#define MAX_CAPACITY \ + ((UINT32_MAX / sizeof(char16_t)) - (sizeof(Buffer) + sizeof(char16_t))) + +nsScannerBufferList::Buffer* nsScannerBufferList::AllocBufferFromString( + const nsAString& aString) { + uint32_t len = aString.Length(); + Buffer* buf = AllocBuffer(len); + + if (buf) { + nsAString::const_iterator source; + aString.BeginReading(source); + nsCharTraits<char16_t>::copy(buf->DataStart(), source.get(), len); + } + return buf; +} + +nsScannerBufferList::Buffer* nsScannerBufferList::AllocBuffer( + uint32_t capacity) { + if (capacity > MAX_CAPACITY) return nullptr; + + void* ptr = malloc(sizeof(Buffer) + (capacity + 1) * sizeof(char16_t)); + if (!ptr) return nullptr; + + Buffer* buf = new (ptr) Buffer(); + + buf->mUsageCount = 0; + buf->mDataEnd = buf->DataStart() + capacity; + + // XXX null terminate. this shouldn't be required, but we do it because + // nsScanner erroneously thinks it can dereference DataEnd :-( + *buf->mDataEnd = char16_t(0); + return buf; +} + +void nsScannerBufferList::ReleaseAll() { + while (!mBuffers.isEmpty()) { + Buffer* node = mBuffers.popFirst(); + // printf(">>> freeing buffer @%p\n", node); + free(node); + } +} + +void nsScannerBufferList::SplitBuffer(const Position& pos) { + // splitting to the right keeps the work string and any extant token + // pointing to and holding a reference count on the same buffer. + + Buffer* bufferToSplit = pos.mBuffer; + NS_ASSERTION(bufferToSplit, "null pointer"); + + uint32_t splitOffset = pos.mPosition - bufferToSplit->DataStart(); + NS_ASSERTION(pos.mPosition >= bufferToSplit->DataStart() && + splitOffset <= bufferToSplit->DataLength(), + "split offset is outside buffer"); + + uint32_t len = bufferToSplit->DataLength() - splitOffset; + Buffer* new_buffer = AllocBuffer(len); + if (new_buffer) { + nsCharTraits<char16_t>::copy(new_buffer->DataStart(), + bufferToSplit->DataStart() + splitOffset, len); + InsertAfter(new_buffer, bufferToSplit); + bufferToSplit->SetDataLength(splitOffset); + } +} + +void nsScannerBufferList::DiscardUnreferencedPrefix(Buffer* aBuf) { + if (aBuf == Head()) { + while (!mBuffers.isEmpty() && !Head()->IsInUse()) { + Buffer* buffer = Head(); + buffer->remove(); + free(buffer); + } + } +} + +size_t nsScannerBufferList::Position::Distance(const Position& aStart, + const Position& aEnd) { + size_t result = 0; + if (aStart.mBuffer == aEnd.mBuffer) { + result = aEnd.mPosition - aStart.mPosition; + } else { + result = aStart.mBuffer->DataEnd() - aStart.mPosition; + for (Buffer* b = aStart.mBuffer->Next(); b != aEnd.mBuffer; b = b->Next()) + result += b->DataLength(); + result += aEnd.mPosition - aEnd.mBuffer->DataStart(); + } + return result; +} + +/** + * nsScannerSubstring + */ + +nsScannerSubstring::nsScannerSubstring() + : mStart(nullptr, nullptr), + mEnd(nullptr, nullptr), + mBufferList(nullptr), + mLength(0) {} + +nsScannerSubstring::nsScannerSubstring(const nsAString& s) + : mBufferList(nullptr) { + Rebind(s); +} + +nsScannerSubstring::~nsScannerSubstring() { + release_ownership_of_buffer_list(); +} + +void nsScannerSubstring::Rebind(const nsScannerSubstring& aString, + const nsScannerIterator& aStart, + const nsScannerIterator& aEnd) { + // allow for the case where &aString == this + + aString.acquire_ownership_of_buffer_list(); + release_ownership_of_buffer_list(); + + mStart = aStart; + mEnd = aEnd; + mBufferList = aString.mBufferList; + mLength = Distance(aStart, aEnd); +} + +void nsScannerSubstring::Rebind(const nsAString& aString) { + release_ownership_of_buffer_list(); + + mBufferList = new nsScannerBufferList(AllocBufferFromString(aString)); + + init_range_from_buffer_list(); + acquire_ownership_of_buffer_list(); +} + +nsScannerIterator& nsScannerSubstring::BeginReading( + nsScannerIterator& iter) const { + iter.mOwner = this; + + iter.mFragment.mBuffer = mStart.mBuffer; + iter.mFragment.mFragmentStart = mStart.mPosition; + if (mStart.mBuffer == mEnd.mBuffer) + iter.mFragment.mFragmentEnd = mEnd.mPosition; + else + iter.mFragment.mFragmentEnd = mStart.mBuffer->DataEnd(); + + iter.mPosition = mStart.mPosition; + iter.normalize_forward(); + return iter; +} + +nsScannerIterator& nsScannerSubstring::EndReading( + nsScannerIterator& iter) const { + iter.mOwner = this; + + iter.mFragment.mBuffer = mEnd.mBuffer; + iter.mFragment.mFragmentEnd = mEnd.mPosition; + if (mStart.mBuffer == mEnd.mBuffer) + iter.mFragment.mFragmentStart = mStart.mPosition; + else + iter.mFragment.mFragmentStart = mEnd.mBuffer->DataStart(); + + iter.mPosition = mEnd.mPosition; + // must not |normalize_backward| as that would likely invalidate tests like + // |while ( first != last )| + return iter; +} + +bool nsScannerSubstring::GetNextFragment(nsScannerFragment& frag) const { + // check to see if we are at the end of the buffer list + if (frag.mBuffer == mEnd.mBuffer) return false; + + frag.mBuffer = frag.mBuffer->getNext(); + + if (frag.mBuffer == mStart.mBuffer) + frag.mFragmentStart = mStart.mPosition; + else + frag.mFragmentStart = frag.mBuffer->DataStart(); + + if (frag.mBuffer == mEnd.mBuffer) + frag.mFragmentEnd = mEnd.mPosition; + else + frag.mFragmentEnd = frag.mBuffer->DataEnd(); + + return true; +} + +bool nsScannerSubstring::GetPrevFragment(nsScannerFragment& frag) const { + // check to see if we are at the beginning of the buffer list + if (frag.mBuffer == mStart.mBuffer) return false; + + frag.mBuffer = frag.mBuffer->getPrevious(); + + if (frag.mBuffer == mStart.mBuffer) + frag.mFragmentStart = mStart.mPosition; + else + frag.mFragmentStart = frag.mBuffer->DataStart(); + + if (frag.mBuffer == mEnd.mBuffer) + frag.mFragmentEnd = mEnd.mPosition; + else + frag.mFragmentEnd = frag.mBuffer->DataEnd(); + + return true; +} + +/** + * nsScannerString + */ + +nsScannerString::nsScannerString(Buffer* aBuf) { + mBufferList = new nsScannerBufferList(aBuf); + + init_range_from_buffer_list(); + acquire_ownership_of_buffer_list(); +} + +void nsScannerString::AppendBuffer(Buffer* aBuf) { + mBufferList->Append(aBuf); + mLength += aBuf->DataLength(); + + mEnd.mBuffer = aBuf; + mEnd.mPosition = aBuf->DataEnd(); +} + +void nsScannerString::DiscardPrefix(const nsScannerIterator& aIter) { + Position old_start(mStart); + mStart = aIter; + mLength -= Position::Distance(old_start, mStart); + + mStart.mBuffer->IncrementUsageCount(); + old_start.mBuffer->DecrementUsageCount(); + + mBufferList->DiscardUnreferencedPrefix(old_start.mBuffer); +} + +void nsScannerString::UngetReadable(const nsAString& aReadable, + const nsScannerIterator& aInsertPoint) +/* + * Warning: this routine manipulates the shared buffer list in an + * unexpected way. The original design did not really allow for + * insertions, but this call promises that if called for a point after the + * end of all extant token strings, that no token string or the work string + * will be invalidated. + * + * This routine is protected because it is the responsibility of the + * derived class to keep those promises. + */ +{ + Position insertPos(aInsertPoint); + + mBufferList->SplitBuffer(insertPos); + // splitting to the right keeps the work string and any extant token + // pointing to and holding a reference count on the same buffer + + Buffer* new_buffer = AllocBufferFromString(aReadable); + // make a new buffer with all the data to insert... + // ALERT: we may have empty space to re-use in the split buffer, + // measure the cost of this and decide if we should do the work to fill + // it + + Buffer* buffer_to_split = insertPos.mBuffer; + mBufferList->InsertAfter(new_buffer, buffer_to_split); + mLength += aReadable.Length(); + + mEnd.mBuffer = mBufferList->Tail(); + mEnd.mPosition = mEnd.mBuffer->DataEnd(); +} + +/** + * nsScannerSharedSubstring + */ + +void nsScannerSharedSubstring::Rebind(const nsScannerIterator& aStart, + const nsScannerIterator& aEnd) { + // If the start and end positions are inside the same buffer, we must + // acquire ownership of the buffer. If not, we can optimize by not holding + // onto it. + + Buffer* buffer = const_cast<Buffer*>(aStart.buffer()); + bool sameBuffer = buffer == aEnd.buffer(); + + nsScannerBufferList* bufferList; + + if (sameBuffer) { + bufferList = aStart.mOwner->mBufferList; + bufferList->AddRef(); + buffer->IncrementUsageCount(); + } + + if (mBufferList) ReleaseBuffer(); + + if (sameBuffer) { + mBuffer = buffer; + mBufferList = bufferList; + mString.Rebind(aStart.mPosition, aEnd.mPosition); + } else { + mBuffer = nullptr; + mBufferList = nullptr; + CopyUnicodeTo(aStart, aEnd, mString); + } +} + +void nsScannerSharedSubstring::ReleaseBuffer() { + NS_ASSERTION(mBufferList, "Should only be called with non-null mBufferList"); + mBuffer->DecrementUsageCount(); + mBufferList->DiscardUnreferencedPrefix(mBuffer); + mBufferList->Release(); +} + +/** + * utils -- based on code from nsReadableUtils.cpp + */ + +// private helper function +static inline nsAString::iterator& copy_multifragment_string( + nsScannerIterator& first, const nsScannerIterator& last, + nsAString::iterator& result) { + typedef nsCharSourceTraits<nsScannerIterator> source_traits; + typedef nsCharSinkTraits<nsAString::iterator> sink_traits; + + while (first != last) { + uint32_t distance = source_traits::readable_distance(first, last); + sink_traits::write(result, source_traits::read(first), distance); + NS_ASSERTION(distance > 0, + "|copy_multifragment_string| will never terminate"); + source_traits::advance(first, distance); + } + + return result; +} + +bool CopyUnicodeTo(const nsScannerIterator& aSrcStart, + const nsScannerIterator& aSrcEnd, nsAString& aDest) { + mozilla::CheckedInt<nsAString::size_type> distance( + Distance(aSrcStart, aSrcEnd)); + if (!distance.isValid()) { + return false; // overflow detected + } + + if (!aDest.SetLength(distance.value(), mozilla::fallible)) { + aDest.Truncate(); + return false; // out of memory + } + auto writer = aDest.BeginWriting(); + nsScannerIterator fromBegin(aSrcStart); + + copy_multifragment_string(fromBegin, aSrcEnd, writer); + return true; +} + +bool AppendUnicodeTo(const nsScannerIterator& aSrcStart, + const nsScannerIterator& aSrcEnd, nsAString& aDest) { + const nsAString::size_type oldLength = aDest.Length(); + mozilla::CheckedInt<nsAString::size_type> newLen( + Distance(aSrcStart, aSrcEnd)); + newLen += oldLength; + if (!newLen.isValid()) { + return false; // overflow detected + } + + if (!aDest.SetLength(newLen.value(), mozilla::fallible)) + return false; // out of memory + auto writer = aDest.BeginWriting(); + std::advance(writer, oldLength); + nsScannerIterator fromBegin(aSrcStart); + + copy_multifragment_string(fromBegin, aSrcEnd, writer); + return true; +} |