/* -*- 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___ */