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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */
/*
* A class which represents a fragment of text (eg inside a text
* node); if only codepoints below 256 are used, the text is stored as
* a char*; otherwise the text is stored as a char16_t*
*/
#ifndef nsTextFragment_h___
#define nsTextFragment_h___
#include "mozilla/Attributes.h"
#include "mozilla/MemoryReporting.h"
#include "nsString.h"
#include "nsReadableUtils.h"
#include "nsISupportsImpl.h"
class nsString;
// XXX should this normalize the code to keep a \u0000 at the end?
// XXX nsTextFragmentPool?
/**
* A fragment of text. If mIs2b is 1 then the m2b pointer is valid
* otherwise the m1b pointer is valid. If m1b is used then each byte
* of data represents a single ucs2 character with the high byte being
* zero.
*
* This class does not have a virtual destructor therefore it is not
* meant to be subclassed.
*/
class nsTextFragment final {
public:
static nsresult Init();
static void Shutdown();
/**
* Default constructor. Initialize the fragment to be empty.
*/
nsTextFragment()
: m1b(nullptr), mAllBits(0)
{
MOZ_COUNT_CTOR(nsTextFragment);
NS_ASSERTION(sizeof(FragmentBits) == 4, "Bad field packing!");
}
~nsTextFragment();
/**
* Change the contents of this fragment to be a copy of the
* the argument fragment, or to "" if unable to allocate enough memory.
*/
nsTextFragment& operator=(const nsTextFragment& aOther);
/**
* Return true if this fragment is represented by char16_t data
*/
bool Is2b() const
{
return mState.mIs2b;
}
/**
* Return true if this fragment contains Bidi text
* For performance reasons this flag is only set if explicitely requested (by
* setting the aUpdateBidi argument on SetTo or Append to true).
*/
bool IsBidi() const
{
return mState.mIsBidi;
}
/**
* Get a pointer to constant char16_t data.
*/
const char16_t *Get2b() const
{
NS_ASSERTION(Is2b(), "not 2b text");
return m2b;
}
/**
* Get a pointer to constant char data.
*/
const char *Get1b() const
{
NS_ASSERTION(!Is2b(), "not 1b text");
return (const char *)m1b;
}
/**
* Get the length of the fragment. The length is the number of logical
* characters, not the number of bytes to store the characters.
*/
uint32_t GetLength() const
{
return mState.mLength;
}
bool CanGrowBy(size_t n) const
{
return n < (1 << 29) && mState.mLength + n < (1 << 29);
}
/**
* Change the contents of this fragment to be a copy of the given
* buffer. If aUpdateBidi is true, contents of the fragment will be scanned,
* and mState.mIsBidi will be turned on if it includes any Bidi characters.
*/
bool SetTo(const char16_t* aBuffer, int32_t aLength, bool aUpdateBidi);
/**
* Append aData to the end of this fragment. If aUpdateBidi is true, contents
* of the fragment will be scanned, and mState.mIsBidi will be turned on if
* it includes any Bidi characters.
*/
bool Append(const char16_t* aBuffer, uint32_t aLength, bool aUpdateBidi);
/**
* Append the contents of this string fragment to aString
*/
void AppendTo(nsAString& aString) const {
if (!AppendTo(aString, mozilla::fallible)) {
aString.AllocFailed(aString.Length() + GetLength());
}
}
/**
* Append the contents of this string fragment to aString
* @return false if an out of memory condition is detected, true otherwise
*/
MOZ_MUST_USE
bool AppendTo(nsAString& aString,
const mozilla::fallible_t& aFallible) const {
if (mState.mIs2b) {
bool ok = aString.Append(m2b, mState.mLength, aFallible);
if (!ok) {
return false;
}
return true;
} else {
return AppendASCIItoUTF16(Substring(m1b, mState.mLength), aString,
aFallible);
}
}
/**
* Append a substring of the contents of this string fragment to aString.
* @param aOffset where to start the substring in this text fragment
* @param aLength the length of the substring
*/
void AppendTo(nsAString& aString, int32_t aOffset, int32_t aLength) const {
if (!AppendTo(aString, aOffset, aLength, mozilla::fallible)) {
aString.AllocFailed(aString.Length() + aLength);
}
}
/**
* Append a substring of the contents of this string fragment to aString.
* @param aString the string in which to append
* @param aOffset where to start the substring in this text fragment
* @param aLength the length of the substring
* @return false if an out of memory condition is detected, true otherwise
*/
MOZ_MUST_USE
bool AppendTo(nsAString& aString, int32_t aOffset, int32_t aLength,
const mozilla::fallible_t& aFallible) const
{
if (mState.mIs2b) {
bool ok = aString.Append(m2b + aOffset, aLength, aFallible);
if (!ok) {
return false;
}
return true;
} else {
return AppendASCIItoUTF16(Substring(m1b + aOffset, aLength), aString,
aFallible);
}
}
/**
* Make a copy of the fragments contents starting at offset for
* count characters. The offset and count will be adjusted to
* lie within the fragments data. The fragments data is converted if
* necessary.
*/
void CopyTo(char16_t *aDest, int32_t aOffset, int32_t aCount);
/**
* Return the character in the text-fragment at the given
* index. This always returns a char16_t.
*/
char16_t CharAt(int32_t aIndex) const
{
NS_ASSERTION(uint32_t(aIndex) < mState.mLength, "bad index");
return mState.mIs2b ? m2b[aIndex] : static_cast<unsigned char>(m1b[aIndex]);
}
struct FragmentBits {
// uint32_t to ensure that the values are unsigned, because we
// want 0/1, not 0/-1!
// Making these bool causes Windows to not actually pack them,
// which causes crashes because we assume this structure is no more than
// 32 bits!
uint32_t mInHeap : 1;
uint32_t mIs2b : 1;
uint32_t mIsBidi : 1;
uint32_t mLength : 29;
};
size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
private:
void ReleaseText();
/**
* Scan the contents of the fragment and turn on mState.mIsBidi if it
* includes any Bidi characters.
*/
void UpdateBidiFlag(const char16_t* aBuffer, uint32_t aLength);
union {
char16_t *m2b;
const char *m1b; // This is const since it can point to shared data
};
union {
uint32_t mAllBits;
FragmentBits mState;
};
};
#endif /* nsTextFragment_h___ */
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