1 /* 2 * Copyright (c) 1989 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Ozan Yigit. 7 * 8 * %sccs.include.redist.c% 9 */ 10 11 #ifndef lint 12 static char sccsid[] = "@(#)look.c 5.3 (Berkeley) 02/26/91"; 13 #endif /* not lint */ 14 15 /* 16 * look.c 17 * Facility: m4 macro processor 18 * by: oz 19 */ 20 21 #include <stdio.h> 22 #include <stdlib.h> 23 #include <string.h> 24 #include "mdef.h" 25 #include "extr.h" 26 27 /* 28 * hash - compute hash value using the proverbial 29 * hashing function. Taken from K&R. 30 */ 31 hash (name) 32 register char *name; 33 { 34 register int h = 0; 35 while (*name) 36 h += *name++; 37 return (h % HASHSIZE); 38 } 39 40 /* 41 * lookup - find name in the hash table 42 * 43 */ 44 ndptr lookup(name) 45 char *name; 46 { 47 register ndptr p; 48 49 for (p = hashtab[hash(name)]; p != nil; p = p->nxtptr) 50 if (strcmp(name, p->name) == 0) 51 break; 52 return (p); 53 } 54 55 /* 56 * addent - hash and create an entry in the hash 57 * table. The new entry is added in front 58 * of a hash bucket. 59 */ 60 ndptr addent(name) 61 char *name; 62 { 63 register int h; 64 ndptr p; 65 66 h = hash(name); 67 if ((p = (ndptr) malloc(sizeof(struct ndblock))) != NULL) { 68 p->nxtptr = hashtab[h]; 69 hashtab[h] = p; 70 p->name = strdup(name); 71 } 72 else 73 error("m4: no more memory."); 74 return p; 75 } 76 77 /* 78 * remhash - remove an entry from the hashtable 79 * 80 */ 81 remhash(name, all) 82 char *name; 83 int all; 84 { 85 register int h; 86 register ndptr xp, tp, mp; 87 88 h = hash(name); 89 mp = hashtab[h]; 90 tp = nil; 91 while (mp != nil) { 92 if (strcmp(mp->name, name) == 0) { 93 mp = mp->nxtptr; 94 if (tp == nil) { 95 freent(hashtab[h]); 96 hashtab[h] = mp; 97 } 98 else { 99 xp = tp->nxtptr; 100 tp->nxtptr = mp; 101 freent(xp); 102 } 103 if (!all) 104 break; 105 } 106 else { 107 tp = mp; 108 mp = mp->nxtptr; 109 } 110 } 111 } 112 113 /* 114 * freent - free a hashtable information block 115 * 116 */ 117 freent(p) 118 ndptr p; 119 { 120 if (!(p->type & STATIC)) { 121 free(p->name); 122 if (p->defn != null) 123 free(p->defn); 124 } 125 free(p); 126 } 127 128