michael@0: /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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:  * This file is based on usc_impl.c from ICU 4.2.0.1, slightly adapted
michael@0:  * for use within Mozilla Gecko, separate from a standard ICU build.
michael@0:  *
michael@0:  * The original ICU license of the code follows:
michael@0:  *
michael@0:  * ICU License - ICU 1.8.1 and later
michael@0:  *
michael@0:  * COPYRIGHT AND PERMISSION NOTICE
michael@0:  * 
michael@0:  * Copyright (c) 1995-2009 International Business Machines Corporation and
michael@0:  * others
michael@0:  *
michael@0:  * All rights reserved.
michael@0:  *
michael@0:  * Permission is hereby granted, free of charge, to any person obtaining a
michael@0:  * copy of this software and associated documentation files (the "Software"),
michael@0:  * to deal in the Software without restriction, including without limitation
michael@0:  * the rights to use, copy, modify, merge, publish, distribute, and/or sell
michael@0:  * copies of the Software, and to permit persons to whom the Software is
michael@0:  * furnished to do so, provided that the above copyright notice(s) and this
michael@0:  * permission notice appear in all copies of the Software and that both the
michael@0:  * above copyright notice(s) and this permission notice appear in supporting
michael@0:  * documentation.
michael@0:  *
michael@0:  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
michael@0:  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
michael@0:  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS.
michael@0:  * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR HOLDERS INCLUDED IN THIS NOTICE
michael@0:  * BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES,
michael@0:  * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
michael@0:  * WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
michael@0:  * ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
michael@0:  * SOFTWARE.
michael@0:  *
michael@0:  * Except as contained in this notice, the name of a copyright holder shall
michael@0:  * not be used in advertising or otherwise to promote the sale, use or other
michael@0:  * dealings in this Software without prior written authorization of the
michael@0:  * copyright holder.
michael@0:  *
michael@0:  * All trademarks and registered trademarks mentioned herein are the property
michael@0:  * of their respective owners. 
michael@0:  */
michael@0: 
michael@0: #include "gfxScriptItemizer.h"
michael@0: #include "nsUnicodeProperties.h"
michael@0: #include "nsCharTraits.h"
michael@0: #include "harfbuzz/hb.h"
michael@0: 
michael@0: #define MOD(sp) ((sp) % PAREN_STACK_DEPTH)
michael@0: #define LIMIT_INC(sp) (((sp) < PAREN_STACK_DEPTH)? (sp) + 1 : PAREN_STACK_DEPTH)
michael@0: #define INC(sp,count) (MOD((sp) + (count)))
michael@0: #define INC1(sp) (INC(sp, 1))
michael@0: #define DEC(sp,count) (MOD((sp) + PAREN_STACK_DEPTH - (count)))
michael@0: #define DEC1(sp) (DEC(sp, 1))
michael@0: #define STACK_IS_EMPTY() (pushCount <= 0)
michael@0: #define STACK_IS_NOT_EMPTY() (! STACK_IS_EMPTY())
michael@0: #define TOP() (parenStack[parenSP])
michael@0: #define SYNC_FIXUP() (fixupCount = 0)
michael@0: 
michael@0: void
michael@0: gfxScriptItemizer::push(uint32_t endPairChar, int32_t scriptCode)
michael@0: {
michael@0:     pushCount  = LIMIT_INC(pushCount);
michael@0:     fixupCount = LIMIT_INC(fixupCount);
michael@0: 
michael@0:     parenSP = INC1(parenSP);
michael@0:     parenStack[parenSP].endPairChar = endPairChar;
michael@0:     parenStack[parenSP].scriptCode = scriptCode;
michael@0: }
michael@0: 
michael@0: void
michael@0: gfxScriptItemizer::pop()
michael@0: {
michael@0:     if (STACK_IS_EMPTY()) {
michael@0:         return;
michael@0:     }
michael@0: 
michael@0:     if (fixupCount > 0) {
michael@0:         fixupCount -= 1;
michael@0:     }
michael@0: 
michael@0:     pushCount -= 1;
michael@0:     parenSP = DEC1(parenSP);
michael@0:   
michael@0:     /* If the stack is now empty, reset the stack
michael@0:        pointers to their initial values.
michael@0:      */
michael@0:     if (STACK_IS_EMPTY()) {
michael@0:         parenSP = -1;
michael@0:     }
michael@0: }
michael@0: 
michael@0: void
michael@0: gfxScriptItemizer::fixup(int32_t scriptCode)
michael@0: {
michael@0:     int32_t fixupSP = DEC(parenSP, fixupCount);
michael@0: 
michael@0:     while (fixupCount-- > 0) {
michael@0:         fixupSP = INC1(fixupSP);
michael@0:         parenStack[fixupSP].scriptCode = scriptCode;
michael@0:     }
michael@0: }
michael@0: 
michael@0: static inline bool
michael@0: SameScript(int32_t runScript, int32_t currCharScript)
michael@0: {
michael@0:     return runScript <= MOZ_SCRIPT_INHERITED ||
michael@0:            currCharScript <= MOZ_SCRIPT_INHERITED ||
michael@0:            currCharScript == runScript;
michael@0: }
michael@0: 
michael@0: // Return whether the char has a mirrored-pair counterpart.
michael@0: // NOTE that this depends on the implementation of nsCharProps records in
michael@0: // nsUnicodeProperties, and may need to be updated if those structures change
michael@0: static inline bool
michael@0: HasMirroredChar(uint32_t aCh)
michael@0: {
michael@0:     return GetCharProps1(aCh).mMirrorOffsetIndex != 0;
michael@0: }
michael@0: 
michael@0: gfxScriptItemizer::gfxScriptItemizer(const char16_t *src, uint32_t length)
michael@0:     : textPtr(src), textLength(length)
michael@0: {
michael@0:     reset();
michael@0: }
michael@0: 
michael@0: void
michael@0: gfxScriptItemizer::SetText(const char16_t *src, uint32_t length)
michael@0: {
michael@0:     textPtr  = src;
michael@0:     textLength = length;
michael@0: 
michael@0:     reset();
michael@0: }
michael@0: 
michael@0: bool
michael@0: gfxScriptItemizer::Next(uint32_t& aRunStart, uint32_t& aRunLimit,
michael@0:                         int32_t& aRunScript)
michael@0: {
michael@0:     /* if we've fallen off the end of the text, we're done */
michael@0:     if (scriptLimit >= textLength) {
michael@0:         return false;
michael@0:     }
michael@0: 
michael@0:     SYNC_FIXUP();
michael@0:     scriptCode = MOZ_SCRIPT_COMMON;
michael@0: 
michael@0:     for (scriptStart = scriptLimit; scriptLimit < textLength; scriptLimit += 1) {
michael@0:         uint32_t ch;
michael@0:         int32_t sc;
michael@0:         uint32_t startOfChar = scriptLimit;
michael@0: 
michael@0:         ch = textPtr[scriptLimit];
michael@0: 
michael@0:         /* decode UTF-16 (may be surrogate pair) */
michael@0:         if (NS_IS_HIGH_SURROGATE(ch) && scriptLimit < textLength - 1) {
michael@0:             uint32_t low = textPtr[scriptLimit + 1];
michael@0:             if (NS_IS_LOW_SURROGATE(low)) {
michael@0:                 ch = SURROGATE_TO_UCS4(ch, low);
michael@0:                 scriptLimit += 1;
michael@0:             }
michael@0:         }
michael@0: 
michael@0:         // Get the nsCharProps2 record for the current character,
michael@0:         // so we can read the script and (if needed) the gen category
michael@0:         // without needing to do two multi-level lookups.
michael@0:         // NOTE that this means we're relying on an implementation detail
michael@0:         // of the nsUnicodeProperties tables, and might have to revise this
michael@0:         // if the nsCharProps records used there are modified in future.
michael@0:         const nsCharProps2& charProps = GetCharProps2(ch);
michael@0: 
michael@0:         // Initialize gc to UNASSIGNED; we'll only set it to the true GC
michael@0:         // if the character has script=COMMON, otherwise we don't care.
michael@0:         uint8_t gc = HB_UNICODE_GENERAL_CATEGORY_UNASSIGNED;
michael@0: 
michael@0:         sc = charProps.mScriptCode;
michael@0:         if (sc == MOZ_SCRIPT_COMMON) {
michael@0:             /*
michael@0:              * Paired character handling:
michael@0:              *
michael@0:              * if it's an open character, push it onto the stack.
michael@0:              * if it's a close character, find the matching open on the
michael@0:              * stack, and use that script code. Any non-matching open
michael@0:              * characters above it on the stack will be popped.
michael@0:              *
michael@0:              * We only do this if the script is COMMON; for chars with
michael@0:              * specific script assignments, we just use them as-is.
michael@0:              */
michael@0:             gc = charProps.mCategory;
michael@0:             if (gc == HB_UNICODE_GENERAL_CATEGORY_OPEN_PUNCTUATION) {
michael@0:                 uint32_t endPairChar = mozilla::unicode::GetMirroredChar(ch);
michael@0:                 if (endPairChar != ch) {
michael@0:                     push(endPairChar, scriptCode);
michael@0:                 }
michael@0:             } else if (gc == HB_UNICODE_GENERAL_CATEGORY_CLOSE_PUNCTUATION &&
michael@0:                 HasMirroredChar(ch))
michael@0:             {
michael@0:                 while (STACK_IS_NOT_EMPTY() && TOP().endPairChar != ch) {
michael@0:                     pop();
michael@0:                 }
michael@0: 
michael@0:                 if (STACK_IS_NOT_EMPTY()) {
michael@0:                     sc = TOP().scriptCode;
michael@0:                 }
michael@0:             }
michael@0:         }
michael@0: 
michael@0:         if (SameScript(scriptCode, sc)) {
michael@0:             if (scriptCode <= MOZ_SCRIPT_INHERITED &&
michael@0:                 sc > MOZ_SCRIPT_INHERITED)
michael@0:             {
michael@0:                 scriptCode = sc;
michael@0:                 fixup(scriptCode);
michael@0:             }
michael@0: 
michael@0:             /*
michael@0:              * if this character is a close paired character,
michael@0:              * pop the matching open character from the stack
michael@0:              */
michael@0:             if (gc == HB_UNICODE_GENERAL_CATEGORY_CLOSE_PUNCTUATION &&
michael@0:                 HasMirroredChar(ch)) {
michael@0:                 pop();
michael@0:             }
michael@0:         } else {
michael@0:             /*
michael@0:              * reset scriptLimit in case it was advanced during reading a
michael@0:              * multiple-code-unit character
michael@0:              */
michael@0:             scriptLimit = startOfChar;
michael@0: 
michael@0:             break;
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     aRunStart = scriptStart;
michael@0:     aRunLimit = scriptLimit;
michael@0:     aRunScript = scriptCode;
michael@0: 
michael@0:     return true;
michael@0: }