mapnik/src/text/scrptrun.cpp

/*
 *******************************************************************************
 *
 *   Copyright (C) 1999-2001, International Business Machines
 *   Corporation and others.  All Rights Reserved.
 *
 *******************************************************************************
 *   file name:  scrptrun.cpp
 *
 *   created on: 10/17/2001
 *   created by: Eric R. Mader
 *
 * NOTE: This file is copied from ICU.
 * http://source.icu-project.org/repos/icu/icu/trunk/license.html
 */

#include <mapnik/warning.hpp>
MAPNIK_DISABLE_WARNING_PUSH
#include <mapnik/warning_ignore.hpp>
#include <unicode/utypes.h>
#include <unicode/uscript.h>
MAPNIK_DISABLE_WARNING_POP

#include <mapnik/text/scrptrun.hpp>

template<class T, std::size_t N>
constexpr std::size_t ARRAY_SIZE(const T (&array)[N]) noexcept
{
    return N;
}

const char ScriptRun::fgClassID = 0;

UChar32 ScriptRun::pairedChars[] = {0x0028, 0x0029, // ascii paired punctuation
                                    0x003c, 0x003e, 0x005b, 0x005d, 0x007b, 0x007d, 0x00ab, 0x00bb, // guillemets
                                    0x2018, 0x2019,                                 // general punctuation
                                    0x201c, 0x201d, 0x2039, 0x203a, 0x3008, 0x3009, // chinese paired punctuation
                                    0x300a, 0x300b, 0x300c, 0x300d, 0x300e, 0x300f, 0x3010, 0x3011,
                                    0x3014, 0x3015, 0x3016, 0x3017, 0x3018, 0x3019, 0x301a, 0x301b};

const int32_t ScriptRun::pairedCharCount = ARRAY_SIZE(pairedChars);
const int32_t ScriptRun::pairedCharPower = 1 << highBit(pairedCharCount);
const int32_t ScriptRun::pairedCharExtra = pairedCharCount - pairedCharPower;

int8_t ScriptRun::highBit(int32_t value)
{
    if (value <= 0)
    {
        return -32;
    }

    int8_t bit = 0;

    if (value >= 1 << 16)
    {
        value >>= 16;
        bit += 16;
    }

    if (value >= 1 << 8)
    {
        value >>= 8;
        bit += 8;
    }

    if (value >= 1 << 4)
    {
        value >>= 4;
        bit += 4;
    }

    if (value >= 1 << 2)
    {
        value >>= 2;
        bit += 2;
    }

    if (value >= 1 << 1)
    {
        value >>= 1;
        bit += 1;
    }

    return bit;
}

int32_t ScriptRun::getPairIndex(UChar32 ch)
{
    int32_t probe = pairedCharPower;
    int32_t index = 0;

    if (ch >= pairedChars[pairedCharExtra])
    {
        index = pairedCharExtra;
    }

    while (probe > (1 << 0))
    {
        probe >>= 1;

        if (ch >= pairedChars[index + probe])
        {
            index += probe;
        }
    }

    if (pairedChars[index] != ch)
    {
        index = -1;
    }

    return index;
}

UBool ScriptRun::sameScript(int32_t scriptOne, int32_t scriptTwo)
{
    return scriptOne <= USCRIPT_INHERITED || scriptTwo <= USCRIPT_INHERITED || scriptOne == scriptTwo;
}

UBool ScriptRun::next()
{
    int32_t startSP = parenSP; // used to find the first new open character
    UErrorCode error = U_ZERO_ERROR;

    // if we've fallen off the end of the text, we're done
    if (scriptEnd >= charLimit)
    {
        return false;
    }

    scriptCode = USCRIPT_COMMON;

    for (scriptStart = scriptEnd; scriptEnd < charLimit; scriptEnd += 1)
    {
        UChar high = charArray[scriptEnd];
        UChar32 ch = high;

        // if the character is a high surrogate and it's not the last one
        // in the text, see if it's followed by a low surrogate
        if (high >= 0xD800 && high <= 0xDBFF && scriptEnd < charLimit - 1)
        {
            UChar low = charArray[scriptEnd + 1];

            // if it is followed by a low surrogate,
            // consume it and form the full character
            if (low >= 0xDC00 && low <= 0xDFFF)
            {
                ch = (high - 0xD800) * 0x0400 + low - 0xDC00 + 0x10000;
                scriptEnd += 1;
            }
        }

        UScriptCode sc = uscript_getScript(ch, &error);
        int32_t pairIndex = getPairIndex(ch);

        // 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 poped.
        if (pairIndex >= 0)
        {
            if ((pairIndex & 1) == 0)
            {
                ++parenSP;
                if (static_cast<std::size_t>(parenSP) < parenStack.size())
                    parenStack[parenSP] = {pairIndex, scriptCode};
                else
                    parenStack.emplace_back(pairIndex, scriptCode);
                startSP = parenSP;
            }
            else if (parenSP >= 0)
            {
                int32_t pi = pairIndex & ~1;

                while (parenSP >= 0 && parenStack[parenSP].pairIndex != pi)
                {
                    parenSP -= 1;
                }

                if (parenSP < startSP)
                {
                    startSP = parenSP;
                }

                if (parenSP >= 0)
                {
                    sc = parenStack[parenSP].scriptCode;
                }
            }
        }

        if (sameScript(scriptCode, sc))
        {
            if (scriptCode <= USCRIPT_INHERITED && sc > USCRIPT_INHERITED)
            {
                scriptCode = sc;
                // now that we have a final script code, fix any open
                // characters we pushed before we knew the script code.
                while (startSP < parenSP)
                {
                    parenStack[++startSP].scriptCode = scriptCode;
                }
            }

            // if this character is a close paired character,
            // pop it from the stack
            if (pairIndex >= 0 && (pairIndex & 1) != 0 && parenSP >= 0)
            {
                parenSP -= 1;
                startSP -= 1;
            }
        }
        else
        {
            // if the run broke on a surrogate pair,
            // end it before the high surrogate
            if (ch >= 0x10000)
            {
                scriptEnd -= 1;
            }

            break;
        }
    }

    return true;
}