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Diffstat (limited to 'parser/htmlparser/nsScannerString.h')
| -rw-r--r-- | parser/htmlparser/nsScannerString.h | 508 |
1 files changed, 508 insertions, 0 deletions
diff --git a/parser/htmlparser/nsScannerString.h b/parser/htmlparser/nsScannerString.h new file mode 100644 index 0000000000..071e4b4761 --- /dev/null +++ b/parser/htmlparser/nsScannerString.h @@ -0,0 +1,508 @@ +/* -*- 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/. */ + +#ifndef nsScannerString_h___ +#define nsScannerString_h___ + +#include "nsString.h" +#include "nsUnicharUtils.h" // for nsCaseInsensitiveStringComparator +#include "mozilla/LinkedList.h" +#include <algorithm> + +/** + * NOTE: nsScannerString (and the other classes defined in this file) are + * not related to nsAString or any of the other xpcom/string classes. + * + * nsScannerString is based on the nsSlidingString implementation that used + * to live in xpcom/string. Now that nsAString is limited to representing + * only single fragment strings, nsSlidingString can no longer be used. + * + * An advantage to this design is that it does not employ any virtual + * functions. + * + * This file uses SCC-style indenting in deference to the nsSlidingString + * code from which this code is derived ;-) + */ + +class nsScannerIterator; +class nsScannerSubstring; +class nsScannerString; + +/** + * nsScannerBufferList + * + * This class maintains a list of heap-allocated Buffer objects. The buffers + * are maintained in a circular linked list. Each buffer has a usage count + * that is decremented by the owning nsScannerSubstring. + * + * The buffer list itself is reference counted. This allows the buffer list + * to be shared by multiple nsScannerSubstring objects. The reference + * counting is not threadsafe, which is not at all a requirement. + * + * When a nsScannerSubstring releases its reference to a buffer list, it + * decrements the usage count of the first buffer in the buffer list that it + * was referencing. It informs the buffer list that it can discard buffers + * starting at that prefix. The buffer list will do so if the usage count of + * that buffer is 0 and if it is the first buffer in the list. It will + * continue to prune buffers starting from the front of the buffer list until + * it finds a buffer that has a usage count that is non-zero. + */ +class nsScannerBufferList { + public: + /** + * Buffer objects are directly followed by a data segment. The start + * of the data segment is determined by increment the |this| pointer + * by 1 unit. + */ + class Buffer : public mozilla::LinkedListElement<Buffer> { + public: + void IncrementUsageCount() { ++mUsageCount; } + void DecrementUsageCount() { --mUsageCount; } + + bool IsInUse() const { return mUsageCount != 0; } + + const char16_t* DataStart() const { return (const char16_t*)(this + 1); } + char16_t* DataStart() { return (char16_t*)(this + 1); } + + const char16_t* DataEnd() const { return mDataEnd; } + char16_t* DataEnd() { return mDataEnd; } + + const Buffer* Next() const { return getNext(); } + Buffer* Next() { return getNext(); } + + const Buffer* Prev() const { return getPrevious(); } + Buffer* Prev() { return getPrevious(); } + + uint32_t DataLength() const { return mDataEnd - DataStart(); } + void SetDataLength(uint32_t len) { mDataEnd = DataStart() + len; } + + private: + friend class nsScannerBufferList; + + int32_t mUsageCount; + char16_t* mDataEnd; + }; + + /** + * Position objects serve as lightweight pointers into a buffer list. + * The mPosition member must be contained with mBuffer->DataStart() + * and mBuffer->DataEnd(). + */ + class Position { + public: + Position() : mBuffer(nullptr), mPosition(nullptr) {} + + Position(Buffer* buffer, char16_t* position) + : mBuffer(buffer), mPosition(position) {} + + inline explicit Position(const nsScannerIterator& aIter); + + inline Position& operator=(const nsScannerIterator& aIter); + + static size_t Distance(const Position& p1, const Position& p2); + + Buffer* mBuffer; + char16_t* mPosition; + }; + + static Buffer* AllocBufferFromString(const nsAString&); + static Buffer* AllocBuffer(uint32_t capacity); // capacity = number of chars + + explicit nsScannerBufferList(Buffer* buf) : mRefCnt(0) { + mBuffers.insertBack(buf); + } + + void AddRef() { ++mRefCnt; } + void Release() { + if (--mRefCnt == 0) delete this; + } + + void Append(Buffer* buf) { mBuffers.insertBack(buf); } + void InsertAfter(Buffer* buf, Buffer* prev) { prev->setNext(buf); } + void SplitBuffer(const Position&); + void DiscardUnreferencedPrefix(Buffer*); + + Buffer* Head() { return mBuffers.getFirst(); } + const Buffer* Head() const { return mBuffers.getFirst(); } + + Buffer* Tail() { return mBuffers.getLast(); } + const Buffer* Tail() const { return mBuffers.getLast(); } + + private: + friend class nsScannerSubstring; + + ~nsScannerBufferList() { ReleaseAll(); } + void ReleaseAll(); + + int32_t mRefCnt; + mozilla::LinkedList<Buffer> mBuffers; +}; + +/** + * nsScannerFragment represents a "slice" of a Buffer object. + */ +struct nsScannerFragment { + typedef nsScannerBufferList::Buffer Buffer; + + const Buffer* mBuffer; + const char16_t* mFragmentStart; + const char16_t* mFragmentEnd; +}; + +/** + * nsScannerSubstring is the base class for nsScannerString. It provides + * access to iterators and methods to bind the substring to another + * substring or nsAString instance. + * + * This class owns the buffer list. + */ +class nsScannerSubstring { + public: + typedef nsScannerBufferList::Buffer Buffer; + typedef nsScannerBufferList::Position Position; + typedef uint32_t size_type; + + nsScannerSubstring(); + explicit nsScannerSubstring(const nsAString& s); + + ~nsScannerSubstring(); + + nsScannerIterator& BeginReading(nsScannerIterator& iter) const; + nsScannerIterator& EndReading(nsScannerIterator& iter) const; + + size_type Length() const { return mLength; } + + int32_t CountChar(char16_t) const; + + void Rebind(const nsScannerSubstring&, const nsScannerIterator&, + const nsScannerIterator&); + void Rebind(const nsAString&); + + const nsAString& AsString() const; + + bool GetNextFragment(nsScannerFragment&) const; + bool GetPrevFragment(nsScannerFragment&) const; + + static inline Buffer* AllocBufferFromString(const nsAString& aStr) { + return nsScannerBufferList::AllocBufferFromString(aStr); + } + static inline Buffer* AllocBuffer(size_type aCapacity) { + return nsScannerBufferList::AllocBuffer(aCapacity); + } + + protected: + void acquire_ownership_of_buffer_list() const { + mBufferList->AddRef(); + mStart.mBuffer->IncrementUsageCount(); + } + + void release_ownership_of_buffer_list() { + if (mBufferList) { + mStart.mBuffer->DecrementUsageCount(); + mBufferList->DiscardUnreferencedPrefix(mStart.mBuffer); + mBufferList->Release(); + } + } + + void init_range_from_buffer_list() { + mStart.mBuffer = mBufferList->Head(); + mStart.mPosition = mStart.mBuffer->DataStart(); + + mEnd.mBuffer = mBufferList->Tail(); + mEnd.mPosition = mEnd.mBuffer->DataEnd(); + + mLength = Position::Distance(mStart, mEnd); + } + + Position mStart; + Position mEnd; + nsScannerBufferList* mBufferList; + size_type mLength; + + // these fields are used to implement AsString + nsDependentSubstring mFlattenedRep; + bool mIsDirty; + + friend class nsScannerSharedSubstring; +}; + +/** + * nsScannerString provides methods to grow and modify a buffer list. + */ +class nsScannerString : public nsScannerSubstring { + public: + explicit nsScannerString(Buffer*); + + // you are giving ownership to the string, it takes and keeps your + // buffer, deleting it when done. + // Use AllocBuffer or AllocBufferFromString to create a Buffer object + // for use with this function. + void AppendBuffer(Buffer*); + + void DiscardPrefix(const nsScannerIterator&); + // any other way you want to do this? + + void UngetReadable(const nsAString& aReadable, + const nsScannerIterator& aCurrentPosition); +}; + +/** + * nsScannerSharedSubstring implements copy-on-write semantics for + * nsScannerSubstring. When you call .writable(), it will copy the data + * and return a mutable string object. This class also manages releasing + * the reference to the scanner buffer when it is no longer needed. + */ + +class nsScannerSharedSubstring { + public: + nsScannerSharedSubstring() : mBuffer(nullptr), mBufferList(nullptr) {} + + ~nsScannerSharedSubstring() { + if (mBufferList) ReleaseBuffer(); + } + + // Acquire a copy-on-write reference to the given substring. + void Rebind(const nsScannerIterator& aStart, const nsScannerIterator& aEnd); + + // Get a mutable reference to this string + nsAString& writable() { + if (mBufferList) MakeMutable(); + + return mString; + } + + // Get a const reference to this string + const nsAString& str() const { return mString; } + + private: + typedef nsScannerBufferList::Buffer Buffer; + + void ReleaseBuffer(); + void MakeMutable(); + + nsDependentSubstring mString; + Buffer* mBuffer; + nsScannerBufferList* mBufferList; +}; + +/** + * nsScannerIterator works just like nsReadingIterator<CharT> except that + * it knows how to iterate over a list of scanner buffers. + */ +class nsScannerIterator { + public: + typedef nsScannerIterator self_type; + typedef ptrdiff_t difference_type; + typedef char16_t value_type; + typedef const char16_t* pointer; + typedef const char16_t& reference; + typedef nsScannerSubstring::Buffer Buffer; + + protected: + nsScannerFragment mFragment; + const char16_t* mPosition; + const nsScannerSubstring* mOwner; + + friend class nsScannerSubstring; + friend class nsScannerSharedSubstring; + + public: + // nsScannerIterator(); // auto-generate + // default constructor is OK nsScannerIterator( const nsScannerIterator& ); // + // auto-generated copy-constructor OK nsScannerIterator& operator=( const + // nsScannerIterator& ); // auto-generated copy-assignment operator OK + + inline void normalize_forward(); + inline void normalize_backward(); + + pointer get() const { return mPosition; } + + char16_t operator*() const { return *get(); } + + const nsScannerFragment& fragment() const { return mFragment; } + + const Buffer* buffer() const { return mFragment.mBuffer; } + + self_type& operator++() { + ++mPosition; + normalize_forward(); + return *this; + } + + self_type operator++(int) { + self_type result(*this); + ++mPosition; + normalize_forward(); + return result; + } + + self_type& operator--() { + normalize_backward(); + --mPosition; + return *this; + } + + self_type operator--(int) { + self_type result(*this); + normalize_backward(); + --mPosition; + return result; + } + + difference_type size_forward() const { + return mFragment.mFragmentEnd - mPosition; + } + + difference_type size_backward() const { + return mPosition - mFragment.mFragmentStart; + } + + self_type& advance(difference_type n) { + while (n > 0) { + difference_type one_hop = std::min(n, size_forward()); + + NS_ASSERTION(one_hop > 0, + "Infinite loop: can't advance a reading iterator beyond the " + "end of a string"); + // perhaps I should |break| if |!one_hop|? + + mPosition += one_hop; + normalize_forward(); + n -= one_hop; + } + + while (n < 0) { + normalize_backward(); + difference_type one_hop = std::max(n, -size_backward()); + + NS_ASSERTION(one_hop < 0, + "Infinite loop: can't advance (backward) a reading iterator " + "beyond the end of a string"); + // perhaps I should |break| if |!one_hop|? + + mPosition += one_hop; + n -= one_hop; + } + + return *this; + } +}; + +inline bool SameFragment(const nsScannerIterator& a, + const nsScannerIterator& b) { + return a.fragment().mFragmentStart == b.fragment().mFragmentStart; +} + +/** + * this class is needed in order to make use of the methods in nsAlgorithm.h + */ +template <> +struct nsCharSourceTraits<nsScannerIterator> { + typedef nsScannerIterator::difference_type difference_type; + + static uint32_t readable_distance(const nsScannerIterator& first, + const nsScannerIterator& last) { + return uint32_t(SameFragment(first, last) ? last.get() - first.get() + : first.size_forward()); + } + + static const nsScannerIterator::value_type* read( + const nsScannerIterator& iter) { + return iter.get(); + } + + static void advance(nsScannerIterator& s, difference_type n) { s.advance(n); } +}; + +/** + * inline methods follow + */ + +inline void nsScannerIterator::normalize_forward() { + while (mPosition == mFragment.mFragmentEnd && + mOwner->GetNextFragment(mFragment)) + mPosition = mFragment.mFragmentStart; +} + +inline void nsScannerIterator::normalize_backward() { + while (mPosition == mFragment.mFragmentStart && + mOwner->GetPrevFragment(mFragment)) + mPosition = mFragment.mFragmentEnd; +} + +inline bool operator==(const nsScannerIterator& lhs, + const nsScannerIterator& rhs) { + return lhs.get() == rhs.get(); +} + +inline bool operator!=(const nsScannerIterator& lhs, + const nsScannerIterator& rhs) { + return lhs.get() != rhs.get(); +} + +inline nsScannerBufferList::Position::Position(const nsScannerIterator& aIter) + : mBuffer(const_cast<Buffer*>(aIter.buffer())), + mPosition(const_cast<char16_t*>(aIter.get())) {} + +inline nsScannerBufferList::Position& nsScannerBufferList::Position::operator=( + const nsScannerIterator& aIter) { + mBuffer = const_cast<Buffer*>(aIter.buffer()); + mPosition = const_cast<char16_t*>(aIter.get()); + return *this; +} + +/** + * scanner string utils + * + * These methods mimic the API provided by nsReadableUtils in xpcom/string. + * Here we provide only the methods that the htmlparser module needs. + */ + +inline size_t Distance(const nsScannerIterator& aStart, + const nsScannerIterator& aEnd) { + typedef nsScannerBufferList::Position Position; + return Position::Distance(Position(aStart), Position(aEnd)); +} + +bool CopyUnicodeTo(const nsScannerIterator& aSrcStart, + const nsScannerIterator& aSrcEnd, nsAString& aDest); + +inline bool CopyUnicodeTo(const nsScannerSubstring& aSrc, nsAString& aDest) { + nsScannerIterator begin, end; + return CopyUnicodeTo(aSrc.BeginReading(begin), aSrc.EndReading(end), aDest); +} + +bool AppendUnicodeTo(const nsScannerIterator& aSrcStart, + const nsScannerIterator& aSrcEnd, nsAString& aDest); + +inline bool AppendUnicodeTo(const nsScannerSubstring& aSrc, nsAString& aDest) { + nsScannerIterator begin, end; + return AppendUnicodeTo(aSrc.BeginReading(begin), aSrc.EndReading(end), aDest); +} + +bool AppendUnicodeTo(const nsScannerIterator& aSrcStart, + const nsScannerIterator& aSrcEnd, + nsScannerSharedSubstring& aDest); + +bool FindCharInReadable(char16_t aChar, nsScannerIterator& aStart, + const nsScannerIterator& aEnd); + +bool FindInReadable(const nsAString& aPattern, nsScannerIterator& aStart, + nsScannerIterator& aEnd, + nsStringComparator = nsTDefaultStringComparator); + +bool RFindInReadable(const nsAString& aPattern, nsScannerIterator& aStart, + nsScannerIterator& aEnd, + nsStringComparator = nsTDefaultStringComparator); + +inline bool CaseInsensitiveFindInReadable(const nsAString& aPattern, + nsScannerIterator& aStart, + nsScannerIterator& aEnd) { + return FindInReadable(aPattern, aStart, aEnd, + nsCaseInsensitiveStringComparator); +} + +#endif // !defined(nsScannerString_h___) |