+/*********************************************************************/
+/* Copyright (C) 2000, HELM Team */
+/* */
+/* This file is part of HELM, an Hypertextual, Electronic */
+/* Library of Mathematics, developed at the Computer Science */
+/* Department, University of Bologna, Italy. */
+/* */
+/* HELM is free software; you can redistribute it and/or */
+/* modify it under the terms of the GNU General Public License */
+/* as published by the Free Software Foundation; either version 2 */
+/* of the License, or (at your option) any later version. */
+/* */
+/* HELM is distributed in the hope that it will be useful, */
+/* but WITHOUT ANY WARRANTY; without even the implied warranty of */
+/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the */
+/* GNU General Public License for more details. */
+/* */
+/* You should have received a copy of the GNU General Public License */
+/* along with HELM; if not, write to the Free Software */
+/* Foundation, Inc., 59 Temple Place - Suite 330, Boston, */
+/* MA 02111-1307, USA. */
+/* */
+/* For details, see the HELM World-Wide-Web page, */
+/* http://cs.unibo.it/helm/. */
+ /*********************************************************************/
+
+/****************************************************************/
+/* STHANDLER.C */
+/****************************************************************/
+/* This module supplies routines for symbol table handling. */
+/* - init_symbol_table(): it initializes the symbol table */
+/* to void. */
+/* - search_bucket(): it searches the symbol table for the */
+/* bucket containing a given identifier, and */
+/* inserts it if it is not present; */
+/****************************************************************/
+/* First draft 11/12/2001, by Andrea Asperti */
+/****************************************************************/
+
+/****************************************************************/
+/* 1. Inclusion of header files. */
+/****************************************************************/
+
+#include <stdio.h>
+#include <malloc.h>
+
+/****************************************************************/
+/* 2. Declarations */
+/****************************************************************/
+
+
+#define DICTSIZE 211
+#define HASH1 4
+#define HASH2 0xf0000000
+#define HASH3 24
+#define EOS '\0'
+
+#define INBODY 0
+#define MAINHYP 1
+#define INHYP 2
+#define INCONCL 3
+#define MAINCONCL 4
+#define INTYPE 5
+#define NOTFOUND 6
+
+/****************************************************************/
+/* 3. Types. */
+/****************************************************************/
+
+struct st_bucket {
+ char *id;
+ /* identifier */
+ struct st_bucket *next_st_bucket;
+ /* next bucket in the list */
+ struct st_bucket *all_next;
+ /* all buckets in symbol
+ table are linked together */
+ int pos[5];
+
+ };
+
+struct st_bucket *dictionary[DICTSIZE];
+ /* pointers to bucket lists */
+
+/****************************************************************/
+/* 4. Definitions of functions to be exported. */
+/****************************************************************/
+
+struct st_bucket *all;
+
+ /* The following function initializes the symbol table to NULL */
+void init_symbol_table()
+{
+ struct st_bucket *st;
+ int i;
+
+ /* initialize the dictionary */
+ for (i = 0; i < DICTSIZE; i++)
+ dictionary[i] = NULL;
+ all = NULL;
+}
+
+ /* The following function searches the symbol table for an identifier */
+ /* and inserts it if it is not present.
+ /* The bucket associated with the given identifier */
+ /* becomes the first one in its list. */
+
+search_bucket(id, where)
+ char *id;
+ /* identifier */
+ int where;
+{
+ int dict_index;
+ /* value returned by the */
+ /* hash function */
+ struct st_bucket
+ *prev,
+ *curr;
+
+ struct st_bucket *st;
+
+ /* apply the hash function */
+ dict_index = hash_pjw(id);
+ /* printf( "%d\n", dict_index); */
+
+ /* scan the bucket list indicated by the hash function */
+ prev = curr = dictionary[dict_index];
+ while ((curr != NULL) && (strcmp(id, curr->id)))
+ {
+ prev = curr;
+ curr = curr->next_st_bucket;
+ }
+ if (curr == NULL)
+ /* the identifier is not in the list */
+ {
+ allocate_bucket(&st,id,where);
+ move_bucket(st,dict_index);
+ return NOTFOUND;
+ }
+ else
+ /* printf("uno=%s\n", id);
+ printf("st=%s\n", curr->id); */
+
+ /* the identifier is already in the list */
+ {
+ /* st = curr; */
+ curr->pos[where] = 1;
+ if (where >= 1)
+ curr->pos[0] = 0; /* it will never be set again to 1 */
+ if (prev != curr)
+ /* the identifier is not in the first position */
+ {
+ prev->next_st_bucket = curr->next_st_bucket;
+ move_bucket(curr,
+ dict_index);
+ };
+ return where;
+ }
+}
+
+print_all()
+{
+ int i;
+ struct st_bucket *curr;
+ curr = all;
+
+ while (curr != NULL)
+ {
+ for (i = 0; i < 5; ++i)
+ if (curr->pos[i] == 1)
+ print_one(curr->id,i);
+ curr = curr->all_next;
+ }
+}
+
+
+/****************************************************************/
+/* 5. Definitions of functions local to the module. */
+/****************************************************************/
+
+print_one(uri,pos)
+ char *uri;
+ int pos;
+{
+ printf("<h:refObj>\n");
+ printf("<h:Occurrence rdf:about=\"http://www.cs.unibo.it/helm/schemas/schema-h.rdf#");
+ if (pos == INBODY)
+ printf("InBody");
+ else if (pos == MAINHYP)
+ printf("MainHypothesis");
+ else if (pos == INHYP)
+ printf("InHypothesis");
+ else if (pos == INCONCL)
+ printf("InConclusion");
+ else if (pos == MAINCONCL)
+ printf("MainConclusion");
+ printf("\" rdf:value=\"");
+ printf("%s", uri);
+ printf("\"/>\n");
+ printf("</h:refObj>\n");
+}
+
+ /* The following function allocates a bucket for an identifier. */
+allocate_bucket(st, id, where)
+ struct st_bucket
+ **st;
+ /* pointer to the bucket to be */
+ /* allocated */
+ char *id;
+ /* identifier */
+ int where;
+{
+ int i;
+
+ *st = (struct st_bucket *)malloc(sizeof(struct st_bucket));
+ (*st)->id = (char *)malloc(sizeof('a')*strlen(id));
+ strcpy((*st)->id,id);
+ (*st)->next_st_bucket = NULL;
+ (*st)->all_next = all;
+ all = *st;
+ for (i = 0; i < 5; ++i)
+ (*st)->pos[i] = 0;
+ (*st)->pos[where] = 1;
+}
+
+ /* The following function moves a bucket to the head of the */
+ /* list in which it lies. */
+move_bucket(st, dict_index)
+ struct st_bucket
+ *st;
+ /* pointer to the bucket to */
+ /* be moved */
+ int dict_index;
+ /* index corresponding to */
+ /* the list in which the */
+ /* bucket lies */
+{
+ st->next_st_bucket = dictionary[dict_index];
+ dictionary[dict_index] = st;
+}
+
+ /* The following function implements Weinberger's hash function. */
+int
+hash_pjw(id)
+ char *id;
+ /* identifier to be hashed */
+{
+ unsigned h,
+ g;
+
+ for (h = 0; *id != EOS; id++)
+ {
+ h = (h << HASH1) + (*id);
+ if (g = h & HASH2)
+ h = h ^ (g >> HASH3) ^ g;
+ }
+ return(h % DICTSIZE);
+}
+
+
+
+
+