helm/metadata/create4/METADATA/sthandler.c

   1 /*********************************************************************/
   2 /*  Copyright (C) 2000, HELM Team                                    */
   3 /*                                                                   */
   4 /* This file is part of HELM, an Hypertextual, Electronic            */
   5 /* Library of Mathematics, developed at the Computer Science         */
   6 /* Department, University of Bologna, Italy.                         */
   7 /*                                                                   */
   8 /* HELM is free software; you can redistribute it and/or             */
   9 /* modify it under the terms of the GNU General Public License       */
  10 /* as published by the Free Software Foundation; either version 2    */
  11 /* of the License, or (at your option) any later version.            */
  12 /*                                                                   */
  13 /* HELM is distributed in the hope that it will be useful,           */
  14 /* but WITHOUT ANY WARRANTY; without even the implied warranty of    */
  15 /* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the     */
  16 /* GNU General Public License for more details.                      */
  17 /*                                                                   */
  18 /* You should have received a copy of the GNU General Public License */
  19 /* along with HELM; if not, write to the Free Software               */
  20 /* Foundation, Inc., 59 Temple Place - Suite 330, Boston,            */
  21 /* MA  02111-1307, USA.                                              */
  22 /*                                                                   */
  23 /* For details, see the HELM World-Wide-Web page,                    */
  24 /* http://cs.unibo.it/helm/.                                         */
  25  /*********************************************************************/
  26
  27 /****************************************************************/
  28 /*                        STHANDLER.C                           */
  29 /****************************************************************/
  30 /* This module supplies routines for symbol table handling.     */
  31 /* - init_symbol_table(): it initializes the symbol table       */
  32 /*                        to void.                              */
  33 /* - search_bucket(): it searches the symbol table for the      */
  34 /*                    bucket containing a given identifier, and */
  35 /*                    inserts it if it is not present;          */
  36 /****************************************************************/
  37 /*           First draft 11/12/2001, by Andrea Asperti          */
  38 /****************************************************************/
  39
  40 /****************************************************************/
  41 /* 1. Inclusion of header files.                                */
  42 /****************************************************************/
  43
  44 #include                <stdio.h>
  45 #include                <malloc.h>
  46
  47 /****************************************************************/
  48 /* 2. Declarations                                              */
  49 /****************************************************************/
  50
  51
  52 #define         DICTSIZE                        211
  53 #define         HASH1                           4
  54 #define         HASH2                           0xf0000000
  55 #define         HASH3                           24
  56 #define         EOS                             '\0'
  57
  58 #define                 INBODY    0
  59 #define                 MAINHYP   1
  60 #define                 INHYP     2
  61 #define                 INCONCL   3
  62 #define                 MAINCONCL 4
  63 #define                 INTYPE    5
  64 #define                 NOTFOUND  6
  65
  66 /****************************************************************/
  67 /* 3. Types.                                                    */
  68 /****************************************************************/
  69
  70 struct st_bucket {
  71                 char                    *id;
  72                                                 /* identifier */
  73                 struct st_bucket        *next_st_bucket;
  74                                                 /* next bucket in the list */
  75                 struct st_bucket        *all_next;
  76                                                /* all buckets in symbol
  77                                                   table are linked together */
  78                 int                     pos[5];
  79
  80                   };
  81
  82 struct st_bucket    *dictionary[DICTSIZE];
  83                                /* pointers to bucket lists */
  84
  85 /****************************************************************/
  86 /* 4. Definitions of functions to be exported.                  */
  87 /****************************************************************/
  88
  89 struct st_bucket        *all;
  90
  91  /* The following function initializes the symbol table to NULL */
  92 void init_symbol_table()
  93 {
  94         struct st_bucket        *st;
  95         int                     i;
  96
  97         /* initialize the dictionary */
  98         for (i = 0; i < DICTSIZE; i++)
  99                 dictionary[i] = NULL;
 100         all = NULL;
 101 }
 102
 103  /* The following function searches the symbol table for an identifier */
 104  /* and inserts it if it is not present.
 105  /* The bucket associated with the given identifier */
 106  /* becomes the first one in its list. */
 107
 108 search_bucket(id, where)
 109         char            *id;
 110                                         /* identifier */
 111         int             where;
 112 {
 113         int             dict_index;
 114                                         /* value returned by the */
 115                                         /* hash function */
 116         struct st_bucket
 117                         *prev,
 118                         *curr;
 119
 120         struct st_bucket *st;
 121
 122         /* apply the hash function */
 123         dict_index = hash_pjw(id);
 124         /* printf( "%d\n", dict_index); */
 125
 126         /* scan the bucket list indicated by the hash function */
 127         prev = curr = dictionary[dict_index];
 128         while ((curr != NULL) && (strcmp(id, curr->id)))
 129           {
 130             prev = curr;
 131             curr = curr->next_st_bucket;
 132           }
 133         if (curr == NULL)
 134           /* the identifier is not in the list */
 135           {
 136             allocate_bucket(&st,id,where);
 137             move_bucket(st,dict_index);
 138             return NOTFOUND;
 139           }
 140         else
 141           /* printf("uno=%s\n", id);
 142              printf("st=%s\n", curr->id); */
 143
 144           /* the identifier is already in the list */
 145           {
 146             /* st = curr; */
 147             curr->pos[where] = 1;
 148             if (where >= 1)
 149               curr->pos[0] = 0; /* it will never be set again to 1 */
 150             if (prev != curr)
 151               /* the identifier is not in the first position */
 152               {
 153                 prev->next_st_bucket = curr->next_st_bucket;
 154                 move_bucket(curr,
 155                             dict_index);
 156               };
 157             return where;
 158           }
 159 }
 160
 161 print_all()
 162 {
 163         int i;
 164         struct st_bucket *curr;
 165         curr = all;
 166
 167         while (curr != NULL)
 168           {
 169             for (i = 0; i < 5; ++i)
 170               if (curr->pos[i] == 1)
 171                print_one(curr->id,i);
 172             curr = curr->all_next;
 173           }
 174 }
 175
 176
 177 /****************************************************************/
 178 /* 5. Definitions of functions local to the module.             */
 179 /****************************************************************/
 180
 181 print_one(uri,pos)
 182      char    *uri;
 183      int     pos;
 184 {
 185     printf("<h:refObj>\n");
 186     printf("<h:Occurrence rdf:about=\"http://www.cs.unibo.it/helm/schemas/schema-h.rdf#");
 187     if (pos == INBODY)
 188        printf("InBody");
 189     else if (pos == MAINHYP)
 190        printf("MainHypothesis");
 191     else if (pos == INHYP)
 192        printf("InHypothesis");
 193     else if (pos == INCONCL)
 194        printf("InConclusion");
 195     else if (pos == MAINCONCL)
 196        printf("MainConclusion");
 197     printf("\" rdf:value=\"");
 198     printf("%s", uri);
 199     printf("\"/>\n");
 200     printf("</h:refObj>\n");
 201 }
 202
 203  /* The following function allocates a bucket for an identifier. */
 204 allocate_bucket(st, id, where)
 205         struct st_bucket
 206                         **st;
 207                                         /* pointer to the bucket to be */
 208                                         /* allocated */
 209         char            *id;
 210                                         /* identifier */
 211         int             where;
 212 {
 213         int i;
 214
 215         *st = (struct st_bucket *)malloc(sizeof(struct st_bucket));
 216         (*st)->id = (char *)malloc(sizeof('a')*strlen(id));
 217         strcpy((*st)->id,id);
 218         (*st)->next_st_bucket = NULL;
 219         (*st)->all_next = all;
 220         all = *st;
 221         for (i = 0; i < 5; ++i)
 222           (*st)->pos[i] = 0;
 223         (*st)->pos[where] = 1;
 224 }
 225
 226  /* The following function moves a bucket to the head of the */
 227  /* list in which it lies. */
 228 move_bucket(st, dict_index)
 229         struct st_bucket
 230                         *st;
 231                                         /* pointer to the bucket to */
 232                                         /* be moved */
 233         int             dict_index;
 234                                         /* index corresponding to */
 235                                         /* the list in which the */
 236                                         /* bucket lies */
 237 {
 238         st->next_st_bucket = dictionary[dict_index];
 239         dictionary[dict_index] = st;
 240 }
 241
 242  /* The following function implements Weinberger's hash function. */
 243 int
 244 hash_pjw(id)
 245         char            *id;
 246                                         /* identifier to be hashed */
 247 {
 248         unsigned        h,
 249                         g;
 250
 251         for (h = 0; *id != EOS; id++)
 252         {
 253                 h = (h << HASH1) + (*id);
 254                 if (g = h & HASH2)
 255                         h = h ^ (g >> HASH3) ^ g;
 256         }
 257         return(h % DICTSIZE);
 258 }
 259
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