68 lines
1.5 KiB
C
68 lines
1.5 KiB
C
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#ifndef RHASHTABLE_H
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#define RHASHTABLE_H
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/*
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ORIGINAL SOURCE IS FROM K&R
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*/
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#include "rmalloc.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#define HASHSIZE 101
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// Structure for the table entries
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typedef struct rnlist {
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struct rnlist *next;
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char *name;
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char *defn;
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} rnlist;
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// Hash table array
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static rnlist *rhashtab[HASHSIZE];
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// Hash function
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unsigned rhash(char *s) {
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unsigned hashval;
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for (hashval = 0; *s != '\0'; s++)
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hashval = *s + 31 * hashval;
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return hashval % HASHSIZE;
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}
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rnlist *rlget(char *s) {
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rnlist *np;
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for (np = rhashtab[rhash(s)]; np != NULL; np = np->next)
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if (strcmp(s, np->name) == 0)
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return np; // Found
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return NULL; // Not found
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}
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// Lookup function
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char *rget(char *s) {
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rnlist *np = rlget(s);
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return np ? np->defn : NULL;
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}
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// Install function (adds a name and definition to the table)
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struct rnlist *rset(char *name, char *defn) {
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struct rnlist *np = NULL;
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unsigned hashval;
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if ((rlget(name)) == NULL) { // Not found
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np = (struct rnlist *)malloc(sizeof(*np));
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if (np == NULL || (np->name = strdup(name)) == NULL)
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return NULL;
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hashval = rhash(name);
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np->next = rhashtab[hashval];
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rhashtab[hashval] = np;
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} else {
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if (np->defn)
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free((void *)np->defn);
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np->defn = NULL;
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}
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if ((np->defn = strdup(defn)) == NULL)
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return NULL;
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return np;
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}
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#endif
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