diff -r 000000000000 -r 6474c204b198 xpcom/string/public/nsUTF8Utils.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/string/public/nsUTF8Utils.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,721 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 nsUTF8Utils_h_
+#define nsUTF8Utils_h_
+
+// This file may be used in two ways: if MOZILLA_INTERNAL_API is defined, this
+// file will provide signatures for the Mozilla abstract string types. It will
+// use XPCOM assertion/debugging macros, etc.
+
+#include "nscore.h"
+#include "mozilla/SSE.h"
+
+#include "nsCharTraits.h"
+
+class UTF8traits
+  {
+    public:
+      static bool isASCII(char c) { return (c & 0x80) == 0x00; }
+      static bool isInSeq(char c) { return (c & 0xC0) == 0x80; }
+      static bool is2byte(char c) { return (c & 0xE0) == 0xC0; }
+      static bool is3byte(char c) { return (c & 0xF0) == 0xE0; }
+      static bool is4byte(char c) { return (c & 0xF8) == 0xF0; }
+      static bool is5byte(char c) { return (c & 0xFC) == 0xF8; }
+      static bool is6byte(char c) { return (c & 0xFE) == 0xFC; }
+  };
+
+/**
+ * Extract the next UCS-4 character from the buffer and return it.  The
+ * pointer passed in is advanced to the start of the next character in the
+ * buffer.  If non-null, the parameters err and overlong are filled in to
+ * indicate that the character was represented by an overlong sequence, or
+ * that an error occurred.
+ */
+
+class UTF8CharEnumerator
+{
+public:
+  static uint32_t NextChar(const char **buffer, const char *end,
+                           bool *err)
+  {
+    NS_ASSERTION(buffer && *buffer, "null buffer!");
+
+    const char *p = *buffer;
+    *err = false;
+
+    if (p >= end)
+      {
+        *err = true;
+
+        return 0;
+      }
+
+    char c = *p++;
+
+    if ( UTF8traits::isASCII(c) )
+      {
+        *buffer = p;
+        return c;
+      }
+
+    uint32_t ucs4;
+    uint32_t minUcs4;
+    int32_t state = 0;
+
+    if (!CalcState(c, ucs4, minUcs4, state)) {
+        NS_ERROR("Not a UTF-8 string. This code should only be used for converting from known UTF-8 strings.");
+        *err = true;
+
+        return 0;
+    }
+
+    while ( state-- )
+      {
+        if (p == end)
+          {
+            *err = true;
+
+            return 0;
+          }
+
+        c = *p++;
+
+        if (!AddByte(c, state, ucs4))
+          {
+            *err = true;
+
+            return 0;
+          }
+      }
+
+      if ( ucs4 < minUcs4 )
+        {
+          // Overlong sequence
+          ucs4 = UCS2_REPLACEMENT_CHAR;
+        }
+      else if ( ucs4 >= 0xD800 &&
+                (ucs4 <= 0xDFFF || ucs4 >= UCS_END))
+        {
+          // Surrogates and code points outside the Unicode range.
+          ucs4 = UCS2_REPLACEMENT_CHAR;
+        }
+
+    *buffer = p;
+    return ucs4;
+  }
+
+private:
+  static bool CalcState(char c, uint32_t& ucs4, uint32_t& minUcs4,
+                          int32_t& state)
+  {
+    if ( UTF8traits::is2byte(c) )
+      {
+        ucs4 = (uint32_t(c) << 6) & 0x000007C0L;
+        state = 1;
+        minUcs4 = 0x00000080;
+      }
+    else if ( UTF8traits::is3byte(c) )
+      {
+        ucs4 = (uint32_t(c) << 12) & 0x0000F000L;
+        state = 2;
+        minUcs4 = 0x00000800;
+      }
+    else if ( UTF8traits::is4byte(c) )
+      {
+        ucs4 = (uint32_t(c) << 18) & 0x001F0000L;
+        state = 3;
+        minUcs4 = 0x00010000;
+      }
+    else if ( UTF8traits::is5byte(c) )
+      {
+        ucs4 = (uint32_t(c) << 24) & 0x03000000L;
+        state = 4;
+        minUcs4 = 0x00200000;
+      }
+    else if ( UTF8traits::is6byte(c) )
+      {
+        ucs4 = (uint32_t(c) << 30) & 0x40000000L;
+        state = 5;
+        minUcs4 = 0x04000000;
+      }
+    else
+      {
+        return false;
+      }
+
+    return true;
+  }
+
+  static bool AddByte(char c, int32_t state, uint32_t& ucs4)
+  {
+    if ( UTF8traits::isInSeq(c) )
+      {
+        int32_t shift = state * 6;
+        ucs4 |= (uint32_t(c) & 0x3F) << shift;
+        return true;
+      }
+
+    return false;
+  }
+};
+
+
+/**
+ * Extract the next UCS-4 character from the buffer and return it.  The
+ * pointer passed in is advanced to the start of the next character in the
+ * buffer.  If non-null, the err parameter is filled in if an error occurs.
+ */
+
+
+class UTF16CharEnumerator
+{
+public:
+  static uint32_t NextChar(const char16_t **buffer, const char16_t *end,
+                           bool *err = nullptr)
+  {
+    NS_ASSERTION(buffer && *buffer, "null buffer!");
+
+    const char16_t *p = *buffer;
+
+    if (p >= end)
+      {
+        NS_ERROR("No input to work with");
+        if (err)
+          *err = true;
+
+        return 0;
+      }
+
+    char16_t c = *p++;
+
+    if (!IS_SURROGATE(c)) // U+0000 - U+D7FF,U+E000 - U+FFFF
+      {
+        if (err)
+          *err = false;
+        *buffer = p;
+        return c;
+      }
+    else if (NS_IS_HIGH_SURROGATE(c)) // U+D800 - U+DBFF
+      {
+        if (p == end)
+          {
+            // Found a high surrogate the end of the buffer. Flag this
+            // as an error and return the Unicode replacement
+            // character 0xFFFD.
+
+            NS_WARNING("Unexpected end of buffer after high surrogate");
+
+            if (err)
+              *err = true;
+            *buffer = p;
+            return 0xFFFD;
+          }
+
+        // D800- DBFF - High Surrogate
+        char16_t h = c;
+
+        c = *p++;
+
+        if (NS_IS_LOW_SURROGATE(c))
+          {
+            // DC00- DFFF - Low Surrogate
+            // N = (H - D800) *400 + 10000 + (L - DC00)
+            uint32_t ucs4 = SURROGATE_TO_UCS4(h, c);
+            if (err)
+              *err = false;
+            *buffer = p;
+            return ucs4;
+          }
+        else
+          {
+            // Found a high surrogate followed by something other than
+            // a low surrogate. Flag this as an error and return the
+            // Unicode replacement character 0xFFFD.  Note that the
+            // pointer to the next character points to the second 16-bit
+            // value, not beyond it, as per Unicode 5.0.0 Chapter 3 C10,
+            // only the first code unit of an illegal sequence must be
+            // treated as an illegally terminated code unit sequence
+            // (also Chapter 3 D91, "isolated [not paired and ill-formed]
+            // UTF-16 code units in the range D800..DFFF are ill-formed").
+            NS_WARNING("got a High Surrogate but no low surrogate");
+
+            if (err)
+              *err = true;
+            *buffer = p - 1;
+            return 0xFFFD;
+          }
+      }
+    else // U+DC00 - U+DFFF
+      {
+        // DC00- DFFF - Low Surrogate
+
+        // Found a low surrogate w/o a preceding high surrogate. Flag
+        // this as an error and return the Unicode replacement
+        // character 0xFFFD.
+
+        NS_WARNING("got a low Surrogate but no high surrogate");
+        if (err)
+          *err = true;
+        *buffer = p;
+        return 0xFFFD;
+      }
+
+    if (err)
+      *err = true;
+    return 0;
+  }
+};
+
+
+/**
+ * A character sink (see |copy_string| in nsAlgorithm.h) for converting
+ * UTF-8 to UTF-16
+ */
+class ConvertUTF8toUTF16
+  {
+    public:
+      typedef char      value_type;
+      typedef char16_t buffer_type;
+
+    ConvertUTF8toUTF16( buffer_type* aBuffer )
+        : mStart(aBuffer), mBuffer(aBuffer), mErrorEncountered(false) {}
+
+    size_t Length() const { return mBuffer - mStart; }
+
+    bool ErrorEncountered() const { return mErrorEncountered; }
+
+    void write( const value_type* start, uint32_t N )
+      {
+        if ( mErrorEncountered )
+          return;
+
+        // algorithm assumes utf8 units won't
+        // be spread across fragments
+        const value_type* p = start;
+        const value_type* end = start + N;
+        buffer_type* out = mBuffer;
+        for ( ; p != end /* && *p */; )
+          {
+            bool err;
+            uint32_t ucs4 = UTF8CharEnumerator::NextChar(&p, end, &err);
+
+            if ( err )
+              {
+                mErrorEncountered = true;
+                mBuffer = out;
+                return;
+              }
+
+            if ( ucs4 >= PLANE1_BASE )
+              {
+                *out++ = (buffer_type)H_SURROGATE(ucs4);
+                *out++ = (buffer_type)L_SURROGATE(ucs4);
+              }
+            else
+              {
+                *out++ = ucs4;
+              }
+          }
+        mBuffer = out;
+      }
+
+    void write_terminator()
+      {
+        *mBuffer = buffer_type(0);
+      }
+
+    private:
+      buffer_type* const mStart;
+      buffer_type* mBuffer;
+      bool mErrorEncountered;
+  };
+
+/**
+ * A character sink (see |copy_string| in nsAlgorithm.h) for computing
+ * the length of the UTF-16 string equivalent to a UTF-8 string.
+ */
+class CalculateUTF8Length
+  {
+    public:
+      typedef char value_type;
+
+    CalculateUTF8Length() : mLength(0), mErrorEncountered(false) { }
+
+    size_t Length() const { return mLength; }
+
+    void write( const value_type* start, uint32_t N )
+      {
+          // ignore any further requests
+        if ( mErrorEncountered )
+            return;
+
+        // algorithm assumes utf8 units won't
+        // be spread across fragments
+        const value_type* p = start;
+        const value_type* end = start + N;
+        for ( ; p < end /* && *p */; ++mLength )
+          {
+            if ( UTF8traits::isASCII(*p) )
+                p += 1;
+            else if ( UTF8traits::is2byte(*p) )
+                p += 2;
+            else if ( UTF8traits::is3byte(*p) )
+                p += 3;
+            else if ( UTF8traits::is4byte(*p) ) {
+                // Because a UTF-8 sequence of 4 bytes represents a codepoint
+                // greater than 0xFFFF, it will become a surrogate pair in the
+                // UTF-16 string, so add 1 more to mLength.
+                // This doesn't happen with is5byte and is6byte because they
+                // are illegal UTF-8 sequences (greater than 0x10FFFF) so get
+                // converted to a single replacement character.
+
+                // However, there is one case when a 4 byte UTF-8 sequence will
+                // only generate 2 UTF-16 bytes. If we have a properly encoded
+                // sequence, but with an invalid value (too small or too big),
+                // that will result in a replacement character being written
+                // This replacement character is encoded as just 1 single
+                // UTF-16 character, which is 2 bytes.
+
+                // The below code therefore only adds 1 to mLength if the UTF8
+                // data will produce a decoded character which is greater than
+                // or equal to 0x010000 and less than 0x0110000.
+
+                // A 4byte UTF8 character is encoded as
+                // 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
+                // Bit 1-3 on the first byte, and bit 5-6 on the second byte,
+                // map to bit 17-21 in the final result. If these bits are
+                // between 0x01 and 0x11, that means that the final result is
+                // between 0x010000 and 0x110000. The below code reads these
+                // bits out and assigns them to c, but shifted up 4 bits to
+                // avoid having to shift twice.
+
+                // It doesn't matter what to do in the case where p + 4 > end
+                // since no UTF16 characters will be written in that case by
+                // ConvertUTF8toUTF16. Likewise it doesn't matter what we do if
+                // any of the surrogate bits are wrong since no UTF16
+                // characters will be written in that case either.
+
+                if (p + 4 <= end) {
+                  uint32_t c = ((uint32_t)(p[0] & 0x07)) << 6 |
+                               ((uint32_t)(p[1] & 0x30));
+                  if (c >= 0x010 && c < 0x110)
+                    ++mLength;
+                }
+
+                p += 4;
+            }
+            else if ( UTF8traits::is5byte(*p) )
+                p += 5;
+            else if ( UTF8traits::is6byte(*p) )
+                p += 6;
+            else // error
+              {
+                ++mLength; // to account for the decrement below
+                break;
+              }
+          }
+        if ( p != end )
+          {
+            NS_ERROR("Not a UTF-8 string. This code should only be used for converting from known UTF-8 strings.");
+            --mLength; // The last multi-byte char wasn't complete, discard it.
+            mErrorEncountered = true;
+          }
+      }
+
+    private:
+      size_t mLength;
+      bool mErrorEncountered;
+  };
+
+/**
+ * A character sink (see |copy_string| in nsAlgorithm.h) for
+ * converting UTF-16 to UTF-8. Treats invalid UTF-16 data as 0xFFFD
+ * (0xEFBFBD in UTF-8).
+ */
+class ConvertUTF16toUTF8
+  {
+    public:
+      typedef char16_t value_type;
+      typedef char      buffer_type;
+
+    // The error handling here is more lenient than that in
+    // |ConvertUTF8toUTF16|, but it's that way for backwards
+    // compatibility.
+
+    ConvertUTF16toUTF8( buffer_type* aBuffer )
+        : mStart(aBuffer), mBuffer(aBuffer) {}
+
+    size_t Size() const { return mBuffer - mStart; }
+
+    void write( const value_type* start, uint32_t N )
+      {
+        buffer_type *out = mBuffer; // gcc isn't smart enough to do this!
+
+        for (const value_type *p = start, *end = start + N; p < end; ++p )
+          {
+            value_type c = *p;
+            if (! (c & 0xFF80)) // U+0000 - U+007F
+              {
+                *out++ = (char)c;
+              }
+            else if (! (c & 0xF800)) // U+0100 - U+07FF
+              {
+                *out++ = 0xC0 | (char)(c >> 6);
+                *out++ = 0x80 | (char)(0x003F & c);
+              }
+            else if (!IS_SURROGATE(c)) // U+0800 - U+D7FF,U+E000 - U+FFFF
+              {
+                *out++ = 0xE0 | (char)(c >> 12);
+                *out++ = 0x80 | (char)(0x003F & (c >> 6));
+                *out++ = 0x80 | (char)(0x003F & c );
+              }
+            else if (NS_IS_HIGH_SURROGATE(c)) // U+D800 - U+DBFF
+              {
+                // D800- DBFF - High Surrogate
+                value_type h = c;
+
+                ++p;
+                if (p == end)
+                  {
+                    // Treat broken characters as the Unicode
+                    // replacement character 0xFFFD (0xEFBFBD in
+                    // UTF-8)
+                    *out++ = '\xEF';
+                    *out++ = '\xBF';
+                    *out++ = '\xBD';
+
+                    NS_WARNING("String ending in half a surrogate pair!");
+
+                    break;
+                  }
+                c = *p;
+
+                if (NS_IS_LOW_SURROGATE(c))
+                  {
+                    // DC00- DFFF - Low Surrogate
+                    // N = (H - D800) *400 + 10000 + ( L - DC00 )
+                    uint32_t ucs4 = SURROGATE_TO_UCS4(h, c);
+
+                    // 0001 0000-001F FFFF
+                    *out++ = 0xF0 | (char)(ucs4 >> 18);
+                    *out++ = 0x80 | (char)(0x003F & (ucs4 >> 12));
+                    *out++ = 0x80 | (char)(0x003F & (ucs4 >> 6));
+                    *out++ = 0x80 | (char)(0x003F & ucs4);
+                  }
+                else
+                  {
+                    // Treat broken characters as the Unicode
+                    // replacement character 0xFFFD (0xEFBFBD in
+                    // UTF-8)
+                    *out++ = '\xEF';
+                    *out++ = '\xBF';
+                    *out++ = '\xBD';
+
+                    // The pointer to the next character points to the second
+                    // 16-bit value, not beyond it, as per Unicode 5.0.0
+                    // Chapter 3 C10, only the first code unit of an illegal
+                    // sequence must be treated as an illegally terminated
+                    // code unit sequence (also Chapter 3 D91, "isolated [not
+                    // paired and ill-formed] UTF-16 code units in the range
+                    // D800..DFFF are ill-formed").
+                    p--;
+
+                    NS_WARNING("got a High Surrogate but no low surrogate");
+                  }
+              }
+            else // U+DC00 - U+DFFF
+              {
+                // Treat broken characters as the Unicode replacement
+                // character 0xFFFD (0xEFBFBD in UTF-8)
+                *out++ = '\xEF';
+                *out++ = '\xBF';
+                *out++ = '\xBD';
+
+                // DC00- DFFF - Low Surrogate
+                NS_WARNING("got a low Surrogate but no high surrogate");
+              }
+          }
+
+        mBuffer = out;
+      }
+
+    void write_terminator()
+      {
+        *mBuffer = buffer_type(0);
+      }
+
+    private:
+      buffer_type* const mStart;
+      buffer_type* mBuffer;
+  };
+
+/**
+ * A character sink (see |copy_string| in nsAlgorithm.h) for computing
+ * the number of bytes a UTF-16 would occupy in UTF-8. Treats invalid
+ * UTF-16 data as 0xFFFD (0xEFBFBD in UTF-8).
+ */
+class CalculateUTF8Size
+  {
+    public:
+      typedef char16_t value_type;
+
+    CalculateUTF8Size()
+      : mSize(0) { }
+
+    size_t Size() const { return mSize; }
+
+    void write( const value_type* start, uint32_t N )
+      {
+        // Assume UCS2 surrogate pairs won't be spread across fragments.
+        for (const value_type *p = start, *end = start + N; p < end; ++p )
+          {
+            value_type c = *p;
+            if (! (c & 0xFF80)) // U+0000 - U+007F
+              mSize += 1;
+            else if (! (c & 0xF800)) // U+0100 - U+07FF
+              mSize += 2;
+            else if (0xD800 != (0xF800 & c)) // U+0800 - U+D7FF,U+E000 - U+FFFF
+              mSize += 3;
+            else if (0xD800 == (0xFC00 & c)) // U+D800 - U+DBFF
+              {
+                ++p;
+                if (p == end)
+                  {
+                    // Treat broken characters as the Unicode
+                    // replacement character 0xFFFD (0xEFBFBD in
+                    // UTF-8)
+                    mSize += 3;
+
+                    NS_WARNING("String ending in half a surrogate pair!");
+
+                    break;
+                  }
+                c = *p;
+
+                if (0xDC00 == (0xFC00 & c))
+                  mSize += 4;
+                else
+                  {
+                    // Treat broken characters as the Unicode
+                    // replacement character 0xFFFD (0xEFBFBD in
+                    // UTF-8)
+                    mSize += 3;
+
+                    // The next code unit is the second 16-bit value, not
+                    // the one beyond it, as per Unicode 5.0.0 Chapter 3 C10,
+                    // only the first code unit of an illegal sequence must
+                    // be treated as an illegally terminated code unit
+                    // sequence (also Chapter 3 D91, "isolated [not paired and
+                    // ill-formed] UTF-16 code units in the range D800..DFFF
+                    // are ill-formed").
+                    p--;
+
+                    NS_WARNING("got a high Surrogate but no low surrogate");
+                  }
+              }
+            else // U+DC00 - U+DFFF
+              {
+                // Treat broken characters as the Unicode replacement
+                // character 0xFFFD (0xEFBFBD in UTF-8)
+                mSize += 3;
+
+                NS_WARNING("got a low Surrogate but no high surrogate");
+              }
+          }
+      }
+
+    private:
+      size_t mSize;
+  };
+
+#ifdef MOZILLA_INTERNAL_API
+/**
+ * A character sink that performs a |reinterpret_cast|-style conversion
+ * from char to char16_t.
+ */
+class LossyConvertEncoding8to16
+  {
+    public:
+      typedef char      value_type;
+      typedef char      input_type;
+      typedef char16_t output_type;
+
+    public:
+      LossyConvertEncoding8to16( char16_t* aDestination ) :
+        mDestination(aDestination) { }
+
+      void
+      write( const char* aSource, uint32_t aSourceLength )
+        {
+#ifdef MOZILLA_MAY_SUPPORT_SSE2
+          if (mozilla::supports_sse2())
+            {
+              write_sse2(aSource, aSourceLength);
+              return;
+            }
+#endif
+          const char* done_writing = aSource + aSourceLength;
+          while ( aSource < done_writing )
+            *mDestination++ = (char16_t)(unsigned char)(*aSource++);
+        }
+
+      void
+      write_sse2( const char* aSource, uint32_t aSourceLength );
+
+      void
+      write_terminator()
+        {
+          *mDestination = (char16_t)(0);
+        }
+
+    private:
+      char16_t* mDestination;
+  };
+
+/**
+ * A character sink that performs a |reinterpret_cast|-style conversion
+ * from char16_t to char.
+ */
+class LossyConvertEncoding16to8
+  {
+    public:
+      typedef char16_t value_type;
+      typedef char16_t input_type;
+      typedef char      output_type;
+
+      LossyConvertEncoding16to8( char* aDestination ) : mDestination(aDestination) { }
+
+      void
+      write( const char16_t* aSource, uint32_t aSourceLength)
+        {
+#ifdef MOZILLA_MAY_SUPPORT_SSE2
+          if (mozilla::supports_sse2())
+            {
+              write_sse2(aSource, aSourceLength);
+              return;
+            }
+#endif
+            const char16_t* done_writing = aSource + aSourceLength;
+            while ( aSource < done_writing )
+              *mDestination++ = (char)(*aSource++);
+        }
+
+#ifdef MOZILLA_MAY_SUPPORT_SSE2
+      void
+      write_sse2( const char16_t* aSource, uint32_t aSourceLength );
+#endif
+
+      void
+      write_terminator()
+        {
+          *mDestination = '\0';
+        }
+
+    private:
+      char *mDestination;
+  };
+#endif // MOZILLA_INTERNAL_API
+
+#endif /* !defined(nsUTF8Utils_h_) */