//========================================================================
//
// CharCodeToUnicode.cc
//
// Copyright 2001-2003 Glyph & Cog, LLC
//
//========================================================================

//========================================================================
//
// Modified under the Poppler project - http://poppler.freedesktop.org
//
// All changes made under the Poppler project to this file are licensed
// under GPL version 2 or later
//
// Copyright (C) 2006, 2008-2010, 2012 Albert Astals Cid <aacid@kde.org>
// Copyright (C) 2007 Julien Rebetez <julienr@svn.gnome.org>
// Copyright (C) 2007 Koji Otani <sho@bbr.jp>
// Copyright (C) 2008 Michael Vrable <mvrable@cs.ucsd.edu>
// Copyright (C) 2008 Vasile Gaburici <gaburici@cs.umd.edu>
// Copyright (C) 2010 William Bader <williambader@hotmail.com>
// Copyright (C) 2010 Jakub Wilk <jwilk@jwilk.net>
// Copyright (C) 2012 Thomas Freitag <Thomas.Freitag@alfa.de>
// Copyright (C) 2012, 2017 Adrian Johnson <ajohnson@redneon.com>
// Copyright (C) 2014 Jiri Slaby <jirislaby@gmail.com>
// Copyright (C) 2015 Marek Kasik <mkasik@redhat.com>
// Copyright (C) 2017 Jean Ghali <jghali@libertysurf.fr>
// Copyright (C) 2018 Klarälvdalens Datakonsult AB, a KDAB Group company, <info@kdab.com>. Work sponsored by the LiMux project of the city of Munich
// Copyright (C) 2018 Adam Reichold <adam.reichold@t-online.de>
//
// To see a description of the changes please see the Changelog file that
// came with your tarball or type make ChangeLog if you are building from git
//
//========================================================================

#include <config.h>

#ifdef USE_GCC_PRAGMAS
#pragma implementation
#endif

#include <stdio.h>
#include <string.h>
#include "goo/glibc.h"
#include "goo/gmem.h"
#include "goo/gfile.h"
#include "goo/GooLikely.h"
#include "goo/GooString.h"
#include "Error.h"
#include "GlobalParams.h"
#include "PSTokenizer.h"
#include "CharCodeToUnicode.h"
#include "UTF.h"

//------------------------------------------------------------------------

struct CharCodeToUnicodeString {
  CharCode c;
  Unicode *u;
  int len;
};

//------------------------------------------------------------------------

static int getCharFromString(void *data) {
  char *p;
  int c;

  p = *(char **)data;
  if (*p) {
    c = *p++;
    *(char **)data = p;
  } else {
    c = EOF;
  }
  return c;
}

static int getCharFromFile(void *data) {
  return fgetc((FILE *)data);
}

//------------------------------------------------------------------------

static int hexCharVals[256] = {
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0x
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 1x
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 2x
   0,  1,  2,  3,  4,  5,  6,  7,  8,  9, -1, -1, -1, -1, -1, -1, // 3x
  -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 4x
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 5x
  -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 6x
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 7x
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 8x
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 9x
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // Ax
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // Bx
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // Cx
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // Dx
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // Ex
  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1  // Fx
};

// Parse a <len>-byte hex string <s> into *<val>.  Returns false on
// error.
static GBool parseHex(char *s, int len, Guint *val) {
  int i, x;

  *val = 0;
  for (i = 0; i < len; ++i) {
    x = hexCharVals[s[i] & 0xff];
    if (x < 0) {
      return gFalse;
    }
    *val = (*val << 4) + x;
  }
  return gTrue;
}

//------------------------------------------------------------------------

CharCodeToUnicode *CharCodeToUnicode::makeIdentityMapping() {
  CharCodeToUnicode *ctu = new CharCodeToUnicode();
  ctu->isIdentity = gTrue;
  ctu->mapLen = 1;
  ctu->map = (Unicode *)gmallocn(ctu->mapLen, sizeof(Unicode));
  return ctu;
}

CharCodeToUnicode *CharCodeToUnicode::parseCIDToUnicode(const char *fileName,
							GooString *collection) {
  FILE *f;
  Unicode *mapA;
  CharCode size, mapLenA;
  char buf[64];
  Unicode u;
  CharCodeToUnicode *ctu;

  if (!(f = openFile(fileName, "r"))) {
    error(errIO, -1, "Couldn't open cidToUnicode file '{0:s}'",
	  fileName);
    return nullptr;
  }

  size = 32768;
  mapA = (Unicode *)gmallocn(size, sizeof(Unicode));
  mapLenA = 0;

  while (getLine(buf, sizeof(buf), f)) {
    if (mapLenA == size) {
      size *= 2;
      mapA = (Unicode *)greallocn(mapA, size, sizeof(Unicode));
    }
    if (sscanf(buf, "%x", &u) == 1) {
      mapA[mapLenA] = u;
    } else {
      error(errSyntaxWarning, -1, "Bad line ({0:d}) in cidToUnicode file '{1:s}'",
	    (int)(mapLenA + 1), fileName);
      mapA[mapLenA] = 0;
    }
    ++mapLenA;
  }
  fclose(f);

  ctu = new CharCodeToUnicode(collection->copy(), mapA, mapLenA, gTrue,
			      nullptr, 0, 0);
  gfree(mapA);
  return ctu;
}

CharCodeToUnicode *CharCodeToUnicode::parseUnicodeToUnicode(
						    GooString *fileName) {
  FILE *f;
  Unicode *mapA;
  CharCodeToUnicodeString *sMapA;
  CharCode size, oldSize, len, sMapSizeA, sMapLenA;
  char buf[256];
  char *tok;
  Unicode u0;
  int uBufSize = 8;
  Unicode *uBuf = (Unicode *)gmallocn(uBufSize, sizeof(Unicode));
  CharCodeToUnicode *ctu;
  int line, n, i;
  char *tokptr;

  if (!(f = openFile(fileName->getCString(), "r"))) {
    gfree(uBuf);
    error(errIO, -1, "Couldn't open unicodeToUnicode file '{0:t}'",
	  fileName);
    return nullptr;
  }

  size = 4096;
  mapA = (Unicode *)gmallocn(size, sizeof(Unicode));
  memset(mapA, 0, size * sizeof(Unicode));
  len = 0;
  sMapA = nullptr;
  sMapSizeA = sMapLenA = 0;

  line = 0;
  while (getLine(buf, sizeof(buf), f)) {
    ++line;
    if (!(tok = strtok_r(buf, " \t\r\n", &tokptr)) ||
	!parseHex(tok, strlen(tok), &u0)) {
      error(errSyntaxWarning, -1, "Bad line ({0:d}) in unicodeToUnicode file '{1:t}'",
	    line, fileName);
      continue;
    }
    n = 0;
    while ((tok = strtok_r(nullptr, " \t\r\n", &tokptr))) {
      if (n >= uBufSize)
      {
        uBufSize += 8;
        uBuf = (Unicode *)greallocn(uBuf, uBufSize, sizeof(Unicode));
      }
      if (!parseHex(tok, strlen(tok), &uBuf[n])) {
	error(errSyntaxWarning, -1, "Bad line ({0:d}) in unicodeToUnicode file '{1:t}'",
	      line, fileName);
	break;
      }
      ++n;
    }
    if (n < 1) {
      error(errSyntaxWarning, -1, "Bad line ({0:d}) in unicodeToUnicode file '{1:t}'",
	    line, fileName);
      continue;
    }
    if (u0 >= size) {
      oldSize = size;
      while (u0 >= size) {
	size *= 2;
      }
      mapA = (Unicode *)greallocn(mapA, size, sizeof(Unicode));
      memset(mapA + oldSize, 0, (size - oldSize) * sizeof(Unicode));
    }
    if (n == 1) {
      mapA[u0] = uBuf[0];
    } else {
      mapA[u0] = 0;
      if (sMapLenA == sMapSizeA) {
	sMapSizeA += 16;
	sMapA = (CharCodeToUnicodeString *)
	          greallocn(sMapA, sMapSizeA, sizeof(CharCodeToUnicodeString));
      }
      sMapA[sMapLenA].c = u0;
      sMapA[sMapLenA].u = (Unicode*)gmallocn(n, sizeof(Unicode));
      for (i = 0; i < n; ++i) {
	sMapA[sMapLenA].u[i] = uBuf[i];
      }
      sMapA[sMapLenA].len = n;
      ++sMapLenA;
    }
    if (u0 >= len) {
      len = u0 + 1;
    }
  }
  fclose(f);

  ctu = new CharCodeToUnicode(fileName->copy(), mapA, len, gTrue,
			      sMapA, sMapLenA, sMapSizeA);
  gfree(mapA);
  gfree(uBuf);
  return ctu;
}

CharCodeToUnicode *CharCodeToUnicode::make8BitToUnicode(Unicode *toUnicode) {
  return new CharCodeToUnicode(nullptr, toUnicode, 256, gTrue, nullptr, 0, 0);
}

CharCodeToUnicode *CharCodeToUnicode::parseCMap(GooString *buf, int nBits) {
  CharCodeToUnicode *ctu;
  char *p;

  ctu = new CharCodeToUnicode(nullptr);
  p = buf->getCString();
  ctu->parseCMap1(&getCharFromString, &p, nBits);
  return ctu;
}

CharCodeToUnicode *CharCodeToUnicode::parseCMapFromFile(GooString *fileName,
  int nBits) {
  CharCodeToUnicode *ctu;
  FILE *f;

  ctu = new CharCodeToUnicode(nullptr);
  if ((f = globalParams->findToUnicodeFile(fileName))) {
    ctu->parseCMap1(&getCharFromFile, f, nBits);
    fclose(f);
  } else {
    error(errSyntaxError, -1, "Couldn't find ToUnicode CMap file for '{0:t}'",
	  fileName);
  }
  return ctu;
}

void CharCodeToUnicode::mergeCMap(GooString *buf, int nBits) {
  char *p;

  p = buf->getCString();
  parseCMap1(&getCharFromString, &p, nBits);
}

void CharCodeToUnicode::parseCMap1(int (*getCharFunc)(void *), void *data,
				   int nBits) {
  PSTokenizer *pst;
  char tok1[256], tok2[256], tok3[256];
  int n1, n2, n3;
  CharCode i;
  CharCode maxCode, code1, code2;
  GooString *name;
  FILE *f;

  maxCode = (nBits == 8) ? 0xff : (nBits == 16) ? 0xffff : 0xffffffff;
  pst = new PSTokenizer(getCharFunc, data);
  pst->getToken(tok1, sizeof(tok1), &n1);
  while (pst->getToken(tok2, sizeof(tok2), &n2)) {
    if (!strcmp(tok2, "usecmap")) {
      if (tok1[0] == '/') {
	name = new GooString(tok1 + 1);
	if ((f = globalParams->findToUnicodeFile(name))) {
	  parseCMap1(&getCharFromFile, f, nBits);
	  fclose(f);
	} else {
	  error(errSyntaxError, -1, "Couldn't find ToUnicode CMap file for '{0:t}'",
		name);
	}
	delete name;
      }
      pst->getToken(tok1, sizeof(tok1), &n1);
    } else if (!strcmp(tok2, "beginbfchar")) {
      while (pst->getToken(tok1, sizeof(tok1), &n1)) {
	if (!strcmp(tok1, "endbfchar")) {
	  break;
	}
	if (!pst->getToken(tok2, sizeof(tok2), &n2) ||
	    !strcmp(tok2, "endbfchar")) {
	  error(errSyntaxWarning, -1, "Illegal entry in bfchar block in ToUnicode CMap");
	  break;
	}
	if (!(tok1[0] == '<' && tok1[n1 - 1] == '>' &&
	      tok2[0] == '<' && tok2[n2 - 1] == '>')) {
	  error(errSyntaxWarning, -1, "Illegal entry in bfchar block in ToUnicode CMap");
	  continue;
	}
	tok1[n1 - 1] = tok2[n2 - 1] = '\0';
	if (!parseHex(tok1 + 1, n1 - 2, &code1)) {
	  error(errSyntaxWarning, -1, "Illegal entry in bfchar block in ToUnicode CMap");
	  continue;
	}
	if (code1 > maxCode) {
	  error(errSyntaxWarning, -1,
		"Invalid entry in bfchar block in ToUnicode CMap");
	}
	addMapping(code1, tok2 + 1, n2 - 2, 0);
      }
      pst->getToken(tok1, sizeof(tok1), &n1);
    } else if (!strcmp(tok2, "beginbfrange")) {
      while (pst->getToken(tok1, sizeof(tok1), &n1)) {
	if (!strcmp(tok1, "endbfrange")) {
	  break;
	}
	if (!pst->getToken(tok2, sizeof(tok2), &n2) ||
	    !strcmp(tok2, "endbfrange") ||
	    !pst->getToken(tok3, sizeof(tok3), &n3) ||
	    !strcmp(tok3, "endbfrange")) {
	  error(errSyntaxWarning, -1, "Illegal entry in bfrange block in ToUnicode CMap");
	  break;
	}
	if (!(tok1[0] == '<' && tok1[n1 - 1] == '>' &&
	      tok2[0] == '<' && tok2[n2 - 1] == '>')) {
	  error(errSyntaxWarning, -1, "Illegal entry in bfrange block in ToUnicode CMap");
	  continue;
	}
	tok1[n1 - 1] = tok2[n2 - 1] = '\0';
	if (!parseHex(tok1 + 1, n1 - 2, &code1) ||
	    !parseHex(tok2 + 1, n2 - 2, &code2)) {
	  error(errSyntaxWarning, -1, "Illegal entry in bfrange block in ToUnicode CMap");
	  continue;
	}
	if (code1 > maxCode || code2 > maxCode) {
	  error(errSyntaxWarning, -1,
		"Invalid entry in bfrange block in ToUnicode CMap");
	  if (code1 > maxCode) {
	    code1 = maxCode;
	  }
	  if (code2 > maxCode) {
	    code2 = maxCode;
	  }
	}
	if (!strcmp(tok3, "[")) {
	  i = 0;
	  while (pst->getToken(tok1, sizeof(tok1), &n1) &&
		 code1 + i <= code2) {
	    if (!strcmp(tok1, "]")) {
	      break;
	    }
	    if (tok1[0] == '<' && tok1[n1 - 1] == '>') {
	      tok1[n1 - 1] = '\0';
	      addMapping(code1 + i, tok1 + 1, n1 - 2, 0);
	    } else {
	      error(errSyntaxWarning, -1, "Illegal entry in bfrange block in ToUnicode CMap");
	    }
	    ++i;
	  }
	} else if (tok3[0] == '<' && tok3[n3 - 1] == '>') {
	  tok3[n3 - 1] = '\0';
	  for (i = 0; code1 <= code2; ++code1, ++i) {
	    addMapping(code1, tok3 + 1, n3 - 2, i);
	  }

	} else {
	  error(errSyntaxWarning, -1, "Illegal entry in bfrange block in ToUnicode CMap");
	}
      }
      pst->getToken(tok1, sizeof(tok1), &n1);
    } else {
      strcpy(tok1, tok2);
    }
  }
  delete pst;
}

void CharCodeToUnicode::addMapping(CharCode code, char *uStr, int n,
				   int offset) {
  CharCode oldLen, i;
  Unicode u;
  int j;

  if (code > 0xffffff) {
    // This is an arbitrary limit to avoid integer overflow issues.
    // (I've seen CMaps with mappings for <ffffffff>.)
    return;
  }
  if (code >= mapLen) {
    oldLen = mapLen;
    mapLen = mapLen ? 2 * mapLen : 256;
    if (code >= mapLen) {
      mapLen = (code + 256) & ~255;
    }
    if (unlikely(code >= mapLen)) {
      error(errSyntaxWarning, -1, "Illegal code value in CharCodeToUnicode::addMapping");
      return;
    } else {
      map = (Unicode *)greallocn(map, mapLen, sizeof(Unicode));
      for (i = oldLen; i < mapLen; ++i) {
        map[i] = 0;
      }
    }
  }
  if (n <= 4) {
    if (!parseHex(uStr, n, &u)) {
      error(errSyntaxWarning, -1, "Illegal entry in ToUnicode CMap");
      return;
    }
    map[code] = u + offset;
    if (!UnicodeIsValid(map[code])) {
      map[code] = 0xfffd;
    }
  } else {
    if (sMapLen >= sMapSize) {
      sMapSize = sMapSize + 16;
      sMap = (CharCodeToUnicodeString *)
	       greallocn(sMap, sMapSize, sizeof(CharCodeToUnicodeString));
    }
    map[code] = 0;
    sMap[sMapLen].c = code;
    int utf16Len = n / 4;
    Unicode *utf16 = (Unicode*)gmallocn(utf16Len, sizeof(Unicode));
    for (j = 0; j < utf16Len; ++j) {
      if (!parseHex(uStr + j*4, 4, &utf16[j])) {
	gfree(utf16);
	error(errSyntaxWarning, -1, "Illegal entry in ToUnicode CMap");
	return;
      }
    }
    utf16[utf16Len - 1] += offset;
    sMap[sMapLen].len = UTF16toUCS4(utf16, utf16Len, &sMap[sMapLen].u);
    gfree(utf16);
    ++sMapLen;
  }
}

CharCodeToUnicode::CharCodeToUnicode() {
  tag = nullptr;
  map = nullptr;
  mapLen = 0;
  sMap = nullptr;
  sMapLen = sMapSize = 0;
  refCnt = 1;
  isIdentity = gFalse;
#ifdef MULTITHREADED
  gInitMutex(&mutex);
#endif
}

CharCodeToUnicode::CharCodeToUnicode(GooString *tagA) {
  CharCode i;

  tag = tagA;
  mapLen = 256;
  map = (Unicode *)gmallocn(mapLen, sizeof(Unicode));
  for (i = 0; i < mapLen; ++i) {
    map[i] = 0;
  }
  sMap = nullptr;
  sMapLen = sMapSize = 0;
  refCnt = 1;
  isIdentity = gFalse;
#ifdef MULTITHREADED
  gInitMutex(&mutex);
#endif
}

CharCodeToUnicode::CharCodeToUnicode(GooString *tagA, Unicode *mapA,
				     CharCode mapLenA, GBool copyMap,
				     CharCodeToUnicodeString *sMapA,
				     int sMapLenA, int sMapSizeA) {
  tag = tagA;
  mapLen = mapLenA;
  if (copyMap) {
    map = (Unicode *)gmallocn(mapLen, sizeof(Unicode));
    memcpy(map, mapA, mapLen * sizeof(Unicode));
  } else {
    map = mapA;
  }
  sMap = sMapA;
  sMapLen = sMapLenA;
  sMapSize = sMapSizeA;
  refCnt = 1;
  isIdentity = gFalse;
#ifdef MULTITHREADED
  gInitMutex(&mutex);
#endif
}

CharCodeToUnicode::~CharCodeToUnicode() {
  if (tag) {
    delete tag;
  }
  gfree(map);
  if (sMap) {
    for (int i = 0; i < sMapLen; ++i) gfree(sMap[i].u);
    gfree(sMap);
  }
#ifdef MULTITHREADED
  gDestroyMutex(&mutex);
#endif
}

void CharCodeToUnicode::incRefCnt() {
#ifdef MULTITHREADED
  gLockMutex(&mutex);
#endif
  ++refCnt;
#ifdef MULTITHREADED
  gUnlockMutex(&mutex);
#endif
}

void CharCodeToUnicode::decRefCnt() {
  GBool done;

#ifdef MULTITHREADED
  gLockMutex(&mutex);
#endif
  done = --refCnt == 0;
#ifdef MULTITHREADED
  gUnlockMutex(&mutex);
#endif
  if (done) {
    delete this;
  }
}

GBool CharCodeToUnicode::match(GooString *tagA) {
  return tag && !tag->cmp(tagA);
}

void CharCodeToUnicode::setMapping(CharCode c, Unicode *u, int len) {
  int i, j;

  if (!map || isIdentity) {
    return;
  }
  if (len == 1) {
    map[c] = u[0];
  } else {
    for (i = 0; i < sMapLen; ++i) {
      if (sMap[i].c == c) {
	gfree(sMap[i].u);
	break;
      }
    }
    if (i == sMapLen) {
      if (sMapLen == sMapSize) {
	sMapSize += 8;
	sMap = (CharCodeToUnicodeString *)
	         greallocn(sMap, sMapSize, sizeof(CharCodeToUnicodeString));
      }
      ++sMapLen;
    }
    map[c] = 0;
    sMap[i].c = c;
    sMap[i].len = len;
    sMap[i].u = (Unicode*)gmallocn(len, sizeof(Unicode));
    for (j = 0; j < len; ++j) {
      if (UnicodeIsValid(u[j])) {
        sMap[i].u[j] = u[j];
      } else {
        sMap[i].u[j] = 0xfffd;
      }
    }
  }
}

int CharCodeToUnicode::mapToUnicode(CharCode c, Unicode **u) {
  int i;

  if (isIdentity) {
    map[0] = (Unicode)c;
    *u = map;
    return 1;
  }
  if (c >= mapLen) {
    return 0;
  }
  if (map[c]) {
    *u = &map[c];
    return 1;
  }
  for (i = sMapLen - 1; i >= 0; --i) { // in reverse so CMap takes precedence
    if (sMap[i].c == c) {
      *u = sMap[i].u;
      return sMap[i].len;
    }
  }
  return 0;
}

int CharCodeToUnicode::mapToCharCode(Unicode* u, CharCode *c, int usize) const {
  //look for charcode in map
  if (usize == 1 || (usize > 1 && !(*u & ~0xff))) {
    if (isIdentity) {
      *c = (CharCode) *u;
      return 1;
    }
    for (CharCode i=0; i<mapLen; i++) {
      if (map[i] == *u) {
        *c = i;
        return 1;
      }
    }
    *c = 'x';
  } else {
    int i, j;
    //for each entry in the sMap
    for (i=0; i<sMapLen; i++) {
      //if the entry's unicode length isn't the same are usize, the strings 
      // are obviously differents
      if (sMap[i].len != usize) continue;
      //compare the string char by char
      for (j=0; j<sMap[i].len; j++) {
        if (sMap[i].u[j] != u[j]) {
          break;
        }
      }

      //we have the same strings
      if (j==sMap[i].len) { 
        *c = sMap[i].c;
        return 1;
      }
    }
  }
  return 0;
}

//------------------------------------------------------------------------

CharCodeToUnicodeCache::CharCodeToUnicodeCache(int sizeA) {
  int i;

  size = sizeA;
  cache = (CharCodeToUnicode **)gmallocn(size, sizeof(CharCodeToUnicode *));
  for (i = 0; i < size; ++i) {
    cache[i] = nullptr;
  }
}

CharCodeToUnicodeCache::~CharCodeToUnicodeCache() {
  int i;

  for (i = 0; i < size; ++i) {
    if (cache[i]) {
      cache[i]->decRefCnt();
    }
  }
  gfree(cache);
}

CharCodeToUnicode *CharCodeToUnicodeCache::getCharCodeToUnicode(GooString *tag) {
  CharCodeToUnicode *ctu;
  int i, j;

  if (cache[0] && cache[0]->match(tag)) {
    cache[0]->incRefCnt();
    return cache[0];
  }
  for (i = 1; i < size; ++i) {
    if (cache[i] && cache[i]->match(tag)) {
      ctu = cache[i];
      for (j = i; j >= 1; --j) {
	cache[j] = cache[j - 1];
      }
      cache[0] = ctu;
      ctu->incRefCnt();
      return ctu;
    }
  }
  return nullptr;
}

void CharCodeToUnicodeCache::add(CharCodeToUnicode *ctu) {
  int i;

  if (cache[size - 1]) {
    cache[size - 1]->decRefCnt();
  }
  for (i = size - 1; i >= 1; --i) {
    cache[i] = cache[i - 1];
  }
  cache[0] = ctu;
  ctu->incRefCnt();
}