icuSources/extra/scrptrun/scrptrun.cpp

   1 /*
   2  *******************************************************************************
   3  *
   4  *   Copyright (C) 1999-2016, International Business Machines
   5  *   Corporation and others.  All Rights Reserved.
   6  *
   7  *******************************************************************************
   8  *   file name:  scrptrun.cpp
   9  *
  10  *   created on: 10/17/2001
  11  *   created by: Eric R. Mader
  12  */
  13
  14 #include "unicode/utypes.h"
  15 #include "unicode/uscript.h"
  16
  17 #include "cmemory.h"
  18 #include "scrptrun.h"
  19
  20 const char ScriptRun::fgClassID=0;
  21
  22 UChar32 ScriptRun::pairedChars[] = {
  23     0x0028, 0x0029, // ascii paired punctuation
  24     0x003c, 0x003e,
  25     0x005b, 0x005d,
  26     0x007b, 0x007d,
  27     0x00ab, 0x00bb, // guillemets
  28     0x2018, 0x2019, // general punctuation
  29     0x201c, 0x201d,
  30     0x2039, 0x203a,
  31     0x3008, 0x3009, // chinese paired punctuation
  32     0x300a, 0x300b,
  33     0x300c, 0x300d,
  34     0x300e, 0x300f,
  35     0x3010, 0x3011,
  36     0x3014, 0x3015,
  37     0x3016, 0x3017,
  38     0x3018, 0x3019,
  39     0x301a, 0x301b
  40 };
  41
  42 const int32_t ScriptRun::pairedCharCount = UPRV_LENGTHOF(pairedChars);
  43 const int32_t ScriptRun::pairedCharPower = 1 << highBit(pairedCharCount);
  44 const int32_t ScriptRun::pairedCharExtra = pairedCharCount - pairedCharPower;
  45
  46 int8_t ScriptRun::highBit(int32_t value)
  47 {
  48     if (value <= 0) {
  49         return -32;
  50     }
  51
  52     int8_t bit = 0;
  53
  54     if (value >= 1 << 16) {
  55         value >>= 16;
  56         bit += 16;
  57     }
  58
  59     if (value >= 1 << 8) {
  60         value >>= 8;
  61         bit += 8;
  62     }
  63
  64     if (value >= 1 << 4) {
  65         value >>= 4;
  66         bit += 4;
  67     }
  68
  69     if (value >= 1 << 2) {
  70         value >>= 2;
  71         bit += 2;
  72     }
  73
  74     if (value >= 1 << 1) {
  75         value >>= 1;
  76         bit += 1;
  77     }
  78
  79     return bit;
  80 }
  81
  82 int32_t ScriptRun::getPairIndex(UChar32 ch)
  83 {
  84     int32_t probe = pairedCharPower;
  85     int32_t index = 0;
  86
  87     if (ch >= pairedChars[pairedCharExtra]) {
  88         index = pairedCharExtra;
  89     }
  90
  91     while (probe > (1 << 0)) {
  92         probe >>= 1;
  93
  94         if (ch >= pairedChars[index + probe]) {
  95             index += probe;
  96         }
  97     }
  98
  99     if (pairedChars[index] != ch) {
 100         index = -1;
 101     }
 102
 103     return index;
 104 }
 105
 106 UBool ScriptRun::sameScript(int32_t scriptOne, int32_t scriptTwo)
 107 {
 108     return scriptOne <= USCRIPT_INHERITED || scriptTwo <= USCRIPT_INHERITED || scriptOne == scriptTwo;
 109 }
 110
 111 UBool ScriptRun::next()
 112 {
 113     int32_t startSP  = parenSP;  // used to find the first new open character
 114     UErrorCode error = U_ZERO_ERROR;
 115
 116     // if we've fallen off the end of the text, we're done
 117     if (scriptEnd >= charLimit) {
 118         return false;
 119     }
 120
 121     scriptCode = USCRIPT_COMMON;
 122
 123     for (scriptStart = scriptEnd; scriptEnd < charLimit; scriptEnd += 1) {
 124         UChar   high = charArray[scriptEnd];
 125         UChar32 ch   = high;
 126
 127         // if the character is a high surrogate and it's not the last one
 128         // in the text, see if it's followed by a low surrogate
 129         if (high >= 0xD800 && high <= 0xDBFF && scriptEnd < charLimit - 1)
 130         {
 131             UChar low = charArray[scriptEnd + 1];
 132
 133             // if it is followed by a low surrogate,
 134             // consume it and form the full character
 135             if (low >= 0xDC00 && low <= 0xDFFF) {
 136                 ch = (high - 0xD800) * 0x0400 + low - 0xDC00 + 0x10000;
 137                 scriptEnd += 1;
 138             }
 139         }
 140
 141         UScriptCode sc = uscript_getScript(ch, &error);
 142         int32_t pairIndex = getPairIndex(ch);
 143
 144         // Paired character handling:
 145         //
 146         // if it's an open character, push it onto the stack.
 147         // if it's a close character, find the matching open on the
 148         // stack, and use that script code. Any non-matching open
 149         // characters above it on the stack will be poped.
 150         if (pairIndex >= 0) {
 151             if ((pairIndex & 1) == 0) {
 152                 parenStack[++parenSP].pairIndex = pairIndex;
 153                 parenStack[parenSP].scriptCode  = scriptCode;
 154             } else if (parenSP >= 0) {
 155                 int32_t pi = pairIndex & ~1;
 156
 157                 while (parenSP >= 0 && parenStack[parenSP].pairIndex != pi) {
 158                     parenSP -= 1;
 159                 }
 160
 161                 if (parenSP < startSP) {
 162                     startSP = parenSP;
 163                 }
 164
 165                 if (parenSP >= 0) {
 166                     sc = parenStack[parenSP].scriptCode;
 167                 }
 168             }
 169         }
 170
 171         if (sameScript(scriptCode, sc)) {
 172             if (scriptCode <= USCRIPT_INHERITED && sc > USCRIPT_INHERITED) {
 173                 scriptCode = sc;
 174
 175                 // now that we have a final script code, fix any open
 176                 // characters we pushed before we knew the script code.
 177                 while (startSP < parenSP) {
 178                     parenStack[++startSP].scriptCode = scriptCode;
 179                 }
 180             }
 181
 182             // if this character is a close paired character,
 183             // pop it from the stack
 184             if (pairIndex >= 0 && (pairIndex & 1) != 0 && parenSP >= 0) {
 185                 parenSP -= 1;
 186                 startSP -= 1;
 187             }
 188         } else {
 189             // if the run broke on a surrogate pair,
 190             // end it before the high surrogate
 191             if (ch >= 0x10000) {
 192                 scriptEnd -= 1;
 193             }
 194
 195             break;
 196         }
 197     }
 198
 199     return true;
 200 }
 201