src/roff/troff/symbol.cpp

   1 // -*- C++ -*-
   2 /* Copyright (C) 1989, 1990, 1991, 1992, 2002 Free Software Foundation, Inc.
   3      Written by James Clark (jjc@jclark.com)
   4
   5 This file is part of groff.
   6
   7 groff is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 2, or (at your option) any later
  10 version.
  11
  12 groff is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License along
  18 with groff; see the file COPYING.  If not, write to the Free Software
  19 Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
  20
  21
  22 #include "troff.h"
  23 #include "symbol.h"
  24
  25 const char **symbol::table = 0;
  26 int symbol::table_used = 0;
  27 int symbol::table_size = 0;
  28 char *symbol::block = 0;
  29 int symbol::block_size = 0;
  30
  31 const symbol NULL_SYMBOL;
  32 const symbol EMPTY_SYMBOL("");
  33
  34 #ifdef BLOCK_SIZE
  35 #undef BLOCK_SIZE
  36 #endif
  37
  38 const int BLOCK_SIZE = 1024;
  39 // the table will increase in size as necessary
  40 // the size will be chosen from the following array
  41 // add some more if you want
  42 static const unsigned int table_sizes[] = {
  43   101, 503, 1009, 2003, 3001, 4001, 5003, 10007, 20011, 40009, 80021,
  44   160001, 500009, 1000003, 1500007, 2000003, 0
  45 };
  46 const double FULL_MAX = 0.3;    // don't let the table get more than this full
  47
  48 static unsigned int hash_string(const char *p)
  49 {
  50   // compute a hash code; this assumes 32-bit unsigned ints
  51   // see p436 of  Compilers by Aho, Sethi & Ullman
  52   // give special treatment to two-character names
  53   unsigned int hc = 0, g;
  54   if (*p != 0) {
  55     hc = *p++;
  56     if (*p != 0) {
  57       hc <<= 7;
  58       hc += *p++;
  59       for (; *p != 0; p++) {
  60         hc <<= 4;
  61         hc += *p;
  62         if ((g = (hc & 0xf0000000)) == 0) {
  63           hc ^= g >> 24;
  64           hc ^= g;
  65         }
  66       }
  67     }
  68   }
  69   return hc;
  70 }
  71
  72 // Tell compiler that a variable is intentionally unused.
  73 inline void unused(void *) { }
  74
  75 symbol::symbol(const char *p, int how)
  76 {
  77   if (p == 0) {
  78     s = 0;
  79     return;
  80   }
  81   if (*p == 0) {
  82     s = "";
  83     return;
  84   }
  85   if (table == 0) {
  86     table_size = table_sizes[0];
  87     table = (const char **)new char*[table_size];
  88     for (int i = 0; i < table_size; i++)
  89       table[i] = 0;
  90     table_used = 0;
  91   }
  92   unsigned int hc = hash_string(p);
  93   const char **pp;
  94   for (pp = table + hc % table_size;
  95        *pp != 0;
  96        (pp == table ? pp = table + table_size - 1 : --pp))
  97     if (strcmp(p, *pp) == 0) {
  98       s = *pp;
  99       return;
 100     }
 101   if (how == MUST_ALREADY_EXIST) {
 102     s = 0;
 103     return;
 104   }
 105   if (table_used  >= table_size - 1 || table_used >= table_size*FULL_MAX) {
 106     const char **old_table = table;
 107     unsigned int old_table_size = table_size;
 108     int i;
 109     for (i = 1; table_sizes[i] <= old_table_size; i++)
 110       if (table_sizes[i] == 0)
 111         fatal("too many symbols");
 112     table_size = table_sizes[i];
 113     table_used = 0;
 114     table = (const char **)new char*[table_size];
 115     for (i = 0; i < table_size; i++)
 116       table[i] = 0;
 117     for (pp = old_table + old_table_size - 1;
 118          pp >= old_table;
 119          --pp) {
 120            symbol temp(*pp, 1); /* insert it into the new table */
 121            unused(&temp);
 122          }
 123     a_delete old_table;
 124     for (pp = table + hc % table_size;
 125          *pp != 0;
 126          (pp == table ? pp = table + table_size - 1 : --pp))
 127       ;
 128   }
 129   ++table_used;
 130   if (how == DONT_STORE) {
 131     s = *pp = p;
 132   }
 133   else {
 134     int len = strlen(p)+1;
 135     if (block == 0 || block_size < len) {
 136       block_size = len > BLOCK_SIZE ? len : BLOCK_SIZE;
 137       block = new char [block_size];
 138     }
 139     (void)strcpy(block, p);
 140     s = *pp = block;
 141     block += len;
 142     block_size -= len;
 143   }
 144 }
 145
 146 symbol concat(symbol s1, symbol s2)
 147 {
 148   char *buf = new char [strlen(s1.contents()) + strlen(s2.contents()) + 1];
 149   strcpy(buf, s1.contents());
 150   strcat(buf, s2.contents());
 151   symbol res(buf);
 152   a_delete buf;
 153   return res;
 154 }