The Tor Browser / file revision

 /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*- */

 /* 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/. */

 /*

  * This file is based on usc_impl.c from ICU 4.2.0.1, slightly adapted

  * for use within Mozilla Gecko, separate from a standard ICU build.

  *

  * The original ICU license of the code follows:

  *

  * ICU License - ICU 1.8.1 and later

  *

  * COPYRIGHT AND PERMISSION NOTICE

  * 

  * Copyright (c) 1995-2009 International Business Machines Corporation and

  * others

  *

  * All rights reserved.

  *

  * Permission is hereby granted, free of charge, to any person obtaining a

  * copy of this software and associated documentation files (the "Software"),

  * to deal in the Software without restriction, including without limitation

  * the rights to use, copy, modify, merge, publish, distribute, and/or sell

  * copies of the Software, and to permit persons to whom the Software is

  * furnished to do so, provided that the above copyright notice(s) and this

  * permission notice appear in all copies of the Software and that both the

  * above copyright notice(s) and this permission notice appear in supporting

  * documentation.

  *

  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS.

  * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR HOLDERS INCLUDED IN THIS NOTICE

  * BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES,

  * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,

  * WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,

  * ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS

  * SOFTWARE.

  *

  * Except as contained in this notice, the name of a copyright holder shall

  * not be used in advertising or otherwise to promote the sale, use or other

  * dealings in this Software without prior written authorization of the

  * copyright holder.

  *

  * All trademarks and registered trademarks mentioned herein are the property

  * of their respective owners. 

  */

 #include "gfxScriptItemizer.h"

 #include "nsUnicodeProperties.h"

 #include "nsCharTraits.h"

 #include "harfbuzz/hb.h"

 #define MOD(sp) ((sp) % PAREN_STACK_DEPTH)

 #define LIMIT_INC(sp) (((sp) < PAREN_STACK_DEPTH)? (sp) + 1 : PAREN_STACK_DEPTH)

 #define INC(sp,count) (MOD((sp) + (count)))

 #define INC1(sp) (INC(sp, 1))

 #define DEC(sp,count) (MOD((sp) + PAREN_STACK_DEPTH - (count)))

 #define DEC1(sp) (DEC(sp, 1))

 #define STACK_IS_EMPTY() (pushCount <= 0)

 #define STACK_IS_NOT_EMPTY() (! STACK_IS_EMPTY())

 #define TOP() (parenStack[parenSP])

 #define SYNC_FIXUP() (fixupCount = 0)

 void

 gfxScriptItemizer::push(uint32_t endPairChar, int32_t scriptCode)

 {

     pushCount  = LIMIT_INC(pushCount);

     fixupCount = LIMIT_INC(fixupCount);

     parenSP = INC1(parenSP);

     parenStack[parenSP].endPairChar = endPairChar;

     parenStack[parenSP].scriptCode = scriptCode;

 }

 void

 gfxScriptItemizer::pop()

 {

     if (STACK_IS_EMPTY()) {

         return;

     }

     if (fixupCount > 0) {

         fixupCount -= 1;

     }

     pushCount -= 1;

     parenSP = DEC1(parenSP);

     /* If the stack is now empty, reset the stack

        pointers to their initial values.

      */

     if (STACK_IS_EMPTY()) {

         parenSP = -1;

     }

 }

 void

 gfxScriptItemizer::fixup(int32_t scriptCode)

 {

     int32_t fixupSP = DEC(parenSP, fixupCount);

     while (fixupCount-- > 0) {

         fixupSP = INC1(fixupSP);

         parenStack[fixupSP].scriptCode = scriptCode;

     }

 }

 static inline bool

 SameScript(int32_t runScript, int32_t currCharScript)

 {

     return runScript <= MOZ_SCRIPT_INHERITED ||

            currCharScript <= MOZ_SCRIPT_INHERITED ||

            currCharScript == runScript;

 }

 // Return whether the char has a mirrored-pair counterpart.

 // NOTE that this depends on the implementation of nsCharProps records in

 // nsUnicodeProperties, and may need to be updated if those structures change

 static inline bool

 HasMirroredChar(uint32_t aCh)

 {

     return GetCharProps1(aCh).mMirrorOffsetIndex != 0;

 }

 gfxScriptItemizer::gfxScriptItemizer(const char16_t *src, uint32_t length)

     : textPtr(src), textLength(length)

 {

     reset();

 }

 void

 gfxScriptItemizer::SetText(const char16_t *src, uint32_t length)

 {

     textPtr  = src;

     textLength = length;

     reset();

 }

 bool

 gfxScriptItemizer::Next(uint32_t& aRunStart, uint32_t& aRunLimit,

                         int32_t& aRunScript)

 {

     /* if we've fallen off the end of the text, we're done */

     if (scriptLimit >= textLength) {

         return false;

     }

     SYNC_FIXUP();

     scriptCode = MOZ_SCRIPT_COMMON;

     for (scriptStart = scriptLimit; scriptLimit < textLength; scriptLimit += 1) {

         uint32_t ch;

         int32_t sc;

         uint32_t startOfChar = scriptLimit;

         ch = textPtr[scriptLimit];

         /* decode UTF-16 (may be surrogate pair) */

         if (NS_IS_HIGH_SURROGATE(ch) && scriptLimit < textLength - 1) {

             uint32_t low = textPtr[scriptLimit + 1];

             if (NS_IS_LOW_SURROGATE(low)) {

                 ch = SURROGATE_TO_UCS4(ch, low);

                 scriptLimit += 1;

             }

         }

         // Get the nsCharProps2 record for the current character,

         // so we can read the script and (if needed) the gen category

         // without needing to do two multi-level lookups.

         // NOTE that this means we're relying on an implementation detail

         // of the nsUnicodeProperties tables, and might have to revise this

         // if the nsCharProps records used there are modified in future.

         const nsCharProps2& charProps = GetCharProps2(ch);

         // Initialize gc to UNASSIGNED; we'll only set it to the true GC

         // if the character has script=COMMON, otherwise we don't care.

         uint8_t gc = HB_UNICODE_GENERAL_CATEGORY_UNASSIGNED;

         sc = charProps.mScriptCode;

         if (sc == MOZ_SCRIPT_COMMON) {

             /*

              * Paired character handling:

              *

              * if it's an open character, push it onto the stack.

              * if it's a close character, find the matching open on the

              * stack, and use that script code. Any non-matching open

              * characters above it on the stack will be popped.

              *

              * We only do this if the script is COMMON; for chars with

              * specific script assignments, we just use them as-is.

              */

             gc = charProps.mCategory;

             if (gc == HB_UNICODE_GENERAL_CATEGORY_OPEN_PUNCTUATION) {

                 uint32_t endPairChar = mozilla::unicode::GetMirroredChar(ch);

                 if (endPairChar != ch) {

                     push(endPairChar, scriptCode);

                 }

             } else if (gc == HB_UNICODE_GENERAL_CATEGORY_CLOSE_PUNCTUATION &&

                 HasMirroredChar(ch))

             {

                 while (STACK_IS_NOT_EMPTY() && TOP().endPairChar != ch) {

                     pop();

                 }

                 if (STACK_IS_NOT_EMPTY()) {

                     sc = TOP().scriptCode;

                 }

             }

         }

         if (SameScript(scriptCode, sc)) {

             if (scriptCode <= MOZ_SCRIPT_INHERITED &&

                 sc > MOZ_SCRIPT_INHERITED)

             {

                 scriptCode = sc;

                 fixup(scriptCode);

             }

             /*

              * if this character is a close paired character,

              * pop the matching open character from the stack

              */

             if (gc == HB_UNICODE_GENERAL_CATEGORY_CLOSE_PUNCTUATION &&

                 HasMirroredChar(ch)) {

                 pop();

             }

         } else {

             /*

              * reset scriptLimit in case it was advanced during reading a

              * multiple-code-unit character

              */

             scriptLimit = startOfChar;

             break;

         }

     }

     aRunStart = scriptStart;

     aRunLimit = scriptLimit;

     aRunScript = scriptCode;

     return true;

 }