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