/* -*- 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) , mIsDirty(true) { } nsScannerSubstring::nsScannerSubstring( const nsAString& s ) : mBufferList(nullptr) , mIsDirty(true) { Rebind(s); } nsScannerSubstring::~nsScannerSubstring() { release_ownership_of_buffer_list(); } int32_t nsScannerSubstring::CountChar( char16_t c ) const { /* re-write this to use a counting sink */ size_type result = 0; size_type lengthToExamine = Length(); nsScannerIterator iter; for ( BeginReading(iter); ; ) { int32_t lengthToExamineInThisFragment = iter.size_forward(); const char16_t* fromBegin = iter.get(); result += size_type(NS_COUNT(fromBegin, fromBegin+lengthToExamineInThisFragment, c)); if ( !(lengthToExamine -= lengthToExamineInThisFragment) ) return result; iter.advance(lengthToExamineInThisFragment); } // never reached; quiets warnings return 0; } 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); mIsDirty = true; } void nsScannerSubstring::Rebind( const nsAString& aString ) { release_ownership_of_buffer_list(); mBufferList = new nsScannerBufferList(AllocBufferFromString(aString)); mIsDirty = true; init_range_from_buffer_list(); acquire_ownership_of_buffer_list(); } const nsSubstring& nsScannerSubstring::AsString() const { if (mIsDirty) { nsScannerSubstring* mutable_this = const_cast<nsScannerSubstring*>(this); if (mStart.mBuffer == mEnd.mBuffer) { // We only have a single fragment to deal with, so just return it // as a substring. mutable_this->mFlattenedRep.Rebind(mStart.mPosition, mEnd.mPosition); } else { // Otherwise, we need to copy the data into a flattened buffer. nsScannerIterator start, end; CopyUnicodeTo(BeginReading(start), EndReading(end), mutable_this->mFlattenedRep); } mutable_this->mIsDirty = false; } return mFlattenedRep; } 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(); mIsDirty = true; } 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); mIsDirty = true; } 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... // BULLSHIT 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(); mIsDirty = true; } /** * 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(); } void nsScannerSharedSubstring::MakeMutable() { nsString temp(mString); // this will force a copy of the data mString.Assign(temp); // mString will now share the just-allocated buffer ReleaseBuffer(); mBuffer = nullptr; mBufferList = nullptr; } /** * 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 ) { nsAString::iterator writer; 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 } aDest.BeginWriting(writer); nsScannerIterator fromBegin(aSrcStart); copy_multifragment_string(fromBegin, aSrcEnd, writer); return true; } bool AppendUnicodeTo( const nsScannerIterator& aSrcStart, const nsScannerIterator& aSrcEnd, nsScannerSharedSubstring& aDest ) { // Check whether we can just create a dependent string. if (aDest.str().IsEmpty()) { // We can just make |aDest| point to the buffer. // This will take care of copying if the buffer spans fragments. aDest.Rebind(aSrcStart, aSrcEnd); return true; } // The dest string is not empty, so it can't be a dependent substring. return AppendUnicodeTo(aSrcStart, aSrcEnd, aDest.writable()); } bool AppendUnicodeTo( const nsScannerIterator& aSrcStart, const nsScannerIterator& aSrcEnd, nsAString& aDest ) { nsAString::iterator writer; const nsAString::size_type oldLength = aDest.Length(); 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 aDest.BeginWriting(writer).advance(oldLength); nsScannerIterator fromBegin(aSrcStart); copy_multifragment_string(fromBegin, aSrcEnd, writer); return true; } bool FindCharInReadable( char16_t aChar, nsScannerIterator& aSearchStart, const nsScannerIterator& aSearchEnd ) { while ( aSearchStart != aSearchEnd ) { int32_t fragmentLength; if ( SameFragment(aSearchStart, aSearchEnd) ) fragmentLength = aSearchEnd.get() - aSearchStart.get(); else fragmentLength = aSearchStart.size_forward(); const char16_t* charFoundAt = nsCharTraits<char16_t>::find(aSearchStart.get(), fragmentLength, aChar); if ( charFoundAt ) { aSearchStart.advance( charFoundAt - aSearchStart.get() ); return true; } aSearchStart.advance(fragmentLength); } return false; } bool FindInReadable( const nsAString& aPattern, nsScannerIterator& aSearchStart, nsScannerIterator& aSearchEnd, const nsStringComparator& compare ) { bool found_it = false; // only bother searching at all if we're given a non-empty range to search if ( aSearchStart != aSearchEnd ) { 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; }