gecko-dev/parser/htmlparser/public/nsScannerString.h

606 строки
17 KiB
C++

/* -*- 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 PRUnichar* DataStart() const { return (const PRUnichar*) (this+1); }
PRUnichar* DataStart() { return ( PRUnichar*) (this+1); }
const PRUnichar* DataEnd() const { return mDataEnd; }
PRUnichar* 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;
PRUnichar* 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() {}
Position( Buffer* buffer, PRUnichar* position )
: mBuffer(buffer)
, mPosition(position)
{}
inline
Position( const nsScannerIterator& aIter );
inline
Position& operator=( const nsScannerIterator& aIter );
static size_t Distance( const Position& p1, const Position& p2 );
Buffer* mBuffer;
PRUnichar* mPosition;
};
static Buffer* AllocBufferFromString( const nsAString& );
static Buffer* AllocBuffer( uint32_t capacity ); // capacity = number of chars
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 PRUnichar* mFragmentStart;
const PRUnichar* 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();
nsScannerSubstring( const nsAString& s );
~nsScannerSubstring();
nsScannerIterator& BeginReading( nsScannerIterator& iter ) const;
nsScannerIterator& EndReading( nsScannerIterator& iter ) const;
size_type Length() const { return mLength; }
int32_t CountChar( PRUnichar ) const;
void Rebind( const nsScannerSubstring&, const nsScannerIterator&, const nsScannerIterator& );
void Rebind( const nsAString& );
const nsSubstring& 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:
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);
void ReplaceCharacter(nsScannerIterator& aPosition, PRUnichar aChar);
};
/**
* 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.
NS_HIDDEN_(void) Rebind(const nsScannerIterator& aStart,
const nsScannerIterator& aEnd);
// Get a mutable reference to this string
nsSubstring& writable()
{
if (mBufferList)
MakeMutable();
return mString;
}
// Get a const reference to this string
const nsSubstring& str() const { return mString; }
private:
typedef nsScannerBufferList::Buffer Buffer;
NS_HIDDEN_(void) ReleaseBuffer();
NS_HIDDEN_(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 PRUnichar value_type;
typedef const PRUnichar* pointer;
typedef const PRUnichar& reference;
typedef nsScannerSubstring::Buffer Buffer;
protected:
nsScannerFragment mFragment;
const PRUnichar* mPosition;
const nsScannerSubstring* mOwner;
friend class nsScannerSubstring;
friend class nsScannerSharedSubstring;
public:
nsScannerIterator() {}
// 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;
}
PRUnichar 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<PRUnichar*>(aIter.get()))
{}
inline
nsScannerBufferList::Position&
nsScannerBufferList::Position::operator=(const nsScannerIterator& aIter)
{
mBuffer = const_cast<Buffer*>(aIter.buffer());
mPosition = const_cast<PRUnichar*>(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));
}
void
CopyUnicodeTo( const nsScannerIterator& aSrcStart,
const nsScannerIterator& aSrcEnd,
nsAString& aDest );
inline
void
CopyUnicodeTo( const nsScannerSubstring& aSrc, nsAString& aDest )
{
nsScannerIterator begin, end;
CopyUnicodeTo(aSrc.BeginReading(begin), aSrc.EndReading(end), aDest);
}
void
AppendUnicodeTo( const nsScannerIterator& aSrcStart,
const nsScannerIterator& aSrcEnd,
nsAString& aDest );
inline
void
AppendUnicodeTo( const nsScannerSubstring& aSrc, nsAString& aDest )
{
nsScannerIterator begin, end;
AppendUnicodeTo(aSrc.BeginReading(begin), aSrc.EndReading(end), aDest);
}
void
AppendUnicodeTo( const nsScannerIterator& aSrcStart,
const nsScannerIterator& aSrcEnd,
nsScannerSharedSubstring& aDest );
bool
FindCharInReadable( PRUnichar aChar,
nsScannerIterator& aStart,
const nsScannerIterator& aEnd );
bool
FindInReadable( const nsAString& aPattern,
nsScannerIterator& aStart,
nsScannerIterator& aEnd,
const nsStringComparator& = nsDefaultStringComparator() );
bool
RFindInReadable( const nsAString& aPattern,
nsScannerIterator& aStart,
nsScannerIterator& aEnd,
const nsStringComparator& = nsDefaultStringComparator() );
inline
bool
CaseInsensitiveFindInReadable( const nsAString& aPattern,
nsScannerIterator& aStart,
nsScannerIterator& aEnd )
{
return FindInReadable(aPattern, aStart, aEnd,
nsCaseInsensitiveStringComparator());
}
#endif // !defined(nsScannerString_h___)