242 lines
6.7 KiB
C++
242 lines
6.7 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/*
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* A class which represents a fragment of text (eg inside a text
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* node); if only codepoints below 256 are used, the text is stored as
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* a char*; otherwise the text is stored as a char16_t*
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*/
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#ifndef nsTextFragment_h___
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#define nsTextFragment_h___
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#include "mozilla/Attributes.h"
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#include "mozilla/MemoryReporting.h"
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#include "nsString.h"
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#include "nsReadableUtils.h"
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#include "nsISupportsImpl.h"
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class nsString;
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// XXX should this normalize the code to keep a \u0000 at the end?
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// XXX nsTextFragmentPool?
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/**
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* A fragment of text. If mIs2b is 1 then the m2b pointer is valid
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* otherwise the m1b pointer is valid. If m1b is used then each byte
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* of data represents a single ucs2 character with the high byte being
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* zero.
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*
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* This class does not have a virtual destructor therefore it is not
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* meant to be subclassed.
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*/
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class nsTextFragment final {
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public:
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static nsresult Init();
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static void Shutdown();
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/**
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* Default constructor. Initialize the fragment to be empty.
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*/
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nsTextFragment()
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: m1b(nullptr), mAllBits(0)
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{
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MOZ_COUNT_CTOR(nsTextFragment);
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NS_ASSERTION(sizeof(FragmentBits) == 4, "Bad field packing!");
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}
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~nsTextFragment();
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/**
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* Change the contents of this fragment to be a copy of the
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* the argument fragment, or to "" if unable to allocate enough memory.
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*/
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nsTextFragment& operator=(const nsTextFragment& aOther);
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/**
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* Return true if this fragment is represented by char16_t data
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*/
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bool Is2b() const
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{
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return mState.mIs2b;
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}
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/**
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* Return true if this fragment contains Bidi text
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* For performance reasons this flag is only set if explicitely requested (by
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* setting the aUpdateBidi argument on SetTo or Append to true).
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*/
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bool IsBidi() const
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{
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return mState.mIsBidi;
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}
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/**
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* Get a pointer to constant char16_t data.
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*/
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const char16_t *Get2b() const
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{
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NS_ASSERTION(Is2b(), "not 2b text");
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return m2b;
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}
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/**
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* Get a pointer to constant char data.
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*/
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const char *Get1b() const
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{
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NS_ASSERTION(!Is2b(), "not 1b text");
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return (const char *)m1b;
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}
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/**
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* Get the length of the fragment. The length is the number of logical
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* characters, not the number of bytes to store the characters.
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*/
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uint32_t GetLength() const
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{
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return mState.mLength;
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}
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bool CanGrowBy(size_t n) const
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{
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return n < (1 << 29) && mState.mLength + n < (1 << 29);
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}
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/**
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* Change the contents of this fragment to be a copy of the given
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* buffer. If aUpdateBidi is true, contents of the fragment will be scanned,
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* and mState.mIsBidi will be turned on if it includes any Bidi characters.
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*/
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bool SetTo(const char16_t* aBuffer, int32_t aLength, bool aUpdateBidi);
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/**
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* Append aData to the end of this fragment. If aUpdateBidi is true, contents
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* of the fragment will be scanned, and mState.mIsBidi will be turned on if
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* it includes any Bidi characters.
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*/
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bool Append(const char16_t* aBuffer, uint32_t aLength, bool aUpdateBidi);
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/**
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* Append the contents of this string fragment to aString
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*/
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void AppendTo(nsAString& aString) const {
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if (!AppendTo(aString, mozilla::fallible)) {
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aString.AllocFailed(aString.Length() + GetLength());
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}
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}
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/**
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* Append the contents of this string fragment to aString
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* @return false if an out of memory condition is detected, true otherwise
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*/
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MOZ_MUST_USE
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bool AppendTo(nsAString& aString,
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const mozilla::fallible_t& aFallible) const {
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if (mState.mIs2b) {
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bool ok = aString.Append(m2b, mState.mLength, aFallible);
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if (!ok) {
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return false;
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}
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return true;
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} else {
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return AppendASCIItoUTF16(Substring(m1b, mState.mLength), aString,
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aFallible);
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}
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}
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/**
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* Append a substring of the contents of this string fragment to aString.
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* @param aOffset where to start the substring in this text fragment
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* @param aLength the length of the substring
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*/
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void AppendTo(nsAString& aString, int32_t aOffset, int32_t aLength) const {
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if (!AppendTo(aString, aOffset, aLength, mozilla::fallible)) {
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aString.AllocFailed(aString.Length() + aLength);
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}
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}
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/**
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* Append a substring of the contents of this string fragment to aString.
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* @param aString the string in which to append
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* @param aOffset where to start the substring in this text fragment
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* @param aLength the length of the substring
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* @return false if an out of memory condition is detected, true otherwise
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*/
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MOZ_MUST_USE
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bool AppendTo(nsAString& aString, int32_t aOffset, int32_t aLength,
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const mozilla::fallible_t& aFallible) const
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{
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if (mState.mIs2b) {
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bool ok = aString.Append(m2b + aOffset, aLength, aFallible);
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if (!ok) {
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return false;
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}
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return true;
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} else {
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return AppendASCIItoUTF16(Substring(m1b + aOffset, aLength), aString,
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aFallible);
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}
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}
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/**
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* Make a copy of the fragments contents starting at offset for
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* count characters. The offset and count will be adjusted to
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* lie within the fragments data. The fragments data is converted if
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* necessary.
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*/
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void CopyTo(char16_t *aDest, int32_t aOffset, int32_t aCount);
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/**
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* Return the character in the text-fragment at the given
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* index. This always returns a char16_t.
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*/
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char16_t CharAt(int32_t aIndex) const
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{
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NS_ASSERTION(uint32_t(aIndex) < mState.mLength, "bad index");
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return mState.mIs2b ? m2b[aIndex] : static_cast<unsigned char>(m1b[aIndex]);
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}
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struct FragmentBits {
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// uint32_t to ensure that the values are unsigned, because we
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// want 0/1, not 0/-1!
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// Making these bool causes Windows to not actually pack them,
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// which causes crashes because we assume this structure is no more than
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// 32 bits!
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uint32_t mInHeap : 1;
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uint32_t mIs2b : 1;
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uint32_t mIsBidi : 1;
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uint32_t mLength : 29;
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};
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size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
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private:
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void ReleaseText();
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/**
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* Scan the contents of the fragment and turn on mState.mIsBidi if it
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* includes any Bidi characters.
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*/
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void UpdateBidiFlag(const char16_t* aBuffer, uint32_t aLength);
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union {
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char16_t *m2b;
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const char *m1b; // This is const since it can point to shared data
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};
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union {
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uint32_t mAllBits;
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FragmentBits mState;
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};
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};
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#endif /* nsTextFragment_h___ */
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