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Annotation of gcc/cpphash.c, revision 1.1

1.1     ! root        1: /* Part of CPP library.  (Macro hash table support.)
        !             2:    Copyright (C) 1986, 87, 89, 92, 93, 94, 1995 Free Software Foundation, Inc.
        !             3:    Written by Per Bothner, 1994.
        !             4:    Based on CCCP program by by Paul Rubin, June 1986
        !             5:    Adapted to ANSI C, Richard Stallman, Jan 1987
        !             6: 
        !             7: This program is free software; you can redistribute it and/or modify it
        !             8: under the terms of the GNU General Public License as published by the
        !             9: Free Software Foundation; either version 2, or (at your option) any
        !            10: later version.
        !            11: 
        !            12: This program is distributed in the hope that it will be useful,
        !            13: but WITHOUT ANY WARRANTY; without even the implied warranty of
        !            14: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
        !            15: GNU General Public License for more details.
        !            16: 
        !            17: You should have received a copy of the GNU General Public License
        !            18: along with this program; if not, write to the Free Software
        !            19: Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
        !            20: 
        !            21:  In other words, you are welcome to use, share and improve this program.
        !            22:  You are forbidden to forbid anyone else to use, share and improve
        !            23:  what you give them.   Help stamp out software-hoarding!  */
        !            24: 
        !            25: #include "cpplib.h"
        !            26: #include "cpphash.h"
        !            27: 
        !            28: extern char *xmalloc PARAMS ((unsigned));
        !            29: 
        !            30: /* Define a generic NULL if one hasn't already been defined.  */
        !            31: 
        !            32: #ifndef NULL
        !            33: #define NULL 0
        !            34: #endif
        !            35: 
        !            36: #ifndef __STDC__
        !            37: #define const
        !            38: #define volatile
        !            39: #endif
        !            40: 
        !            41: /*
        !            42:  * return hash function on name.  must be compatible with the one
        !            43:  * computed a step at a time, elsewhere
        !            44:  */
        !            45: int
        !            46: hashf (name, len, hashsize)
        !            47:      register const U_CHAR *name;
        !            48:      register int len;
        !            49:      int hashsize;
        !            50: {
        !            51:   register int r = 0;
        !            52: 
        !            53:   while (len--)
        !            54:     r = HASHSTEP (r, *name++);
        !            55: 
        !            56:   return MAKE_POS (r) % hashsize;
        !            57: }
        !            58: 
        !            59: /*
        !            60:  * find the most recent hash node for name name (ending with first
        !            61:  * non-identifier char) installed by install
        !            62:  *
        !            63:  * If LEN is >= 0, it is the length of the name.
        !            64:  * Otherwise, compute the length by scanning the entire name.
        !            65:  *
        !            66:  * If HASH is >= 0, it is the precomputed hash code.
        !            67:  * Otherwise, compute the hash code.
        !            68:  */
        !            69: HASHNODE *
        !            70: cpp_lookup (pfile, name, len, hash)
        !            71:      struct parse_file *pfile;
        !            72:      const U_CHAR *name;
        !            73:      int len;
        !            74:      int hash;
        !            75: {
        !            76:   register const U_CHAR *bp;
        !            77:   register HASHNODE *bucket;
        !            78: 
        !            79:   if (len < 0)
        !            80:     {
        !            81:       for (bp = name; is_idchar[*bp]; bp++) ;
        !            82:       len = bp - name;
        !            83:     }
        !            84: 
        !            85:   if (hash < 0)
        !            86:     hash = hashf (name, len, HASHSIZE);
        !            87: 
        !            88:   bucket = hashtab[hash];
        !            89:   while (bucket) {
        !            90:     if (bucket->length == len && strncmp (bucket->name, name, len) == 0)
        !            91:       return bucket;
        !            92:     bucket = bucket->next;
        !            93:   }
        !            94:   return (HASHNODE*) 0;
        !            95: }
        !            96: 
        !            97: /*
        !            98:  * Delete a hash node.  Some weirdness to free junk from macros.
        !            99:  * More such weirdness will have to be added if you define more hash
        !           100:  * types that need it.
        !           101:  */
        !           102: 
        !           103: /* Note that the DEFINITION of a macro is removed from the hash table
        !           104:    but its storage is not freed.  This would be a storage leak
        !           105:    except that it is not reasonable to keep undefining and redefining
        !           106:    large numbers of macros many times.
        !           107:    In any case, this is necessary, because a macro can be #undef'd
        !           108:    in the middle of reading the arguments to a call to it.
        !           109:    If #undef freed the DEFINITION, that would crash.  */
        !           110: 
        !           111: void
        !           112: delete_macro (hp)
        !           113:      HASHNODE *hp;
        !           114: {
        !           115: 
        !           116:   if (hp->prev != NULL)
        !           117:     hp->prev->next = hp->next;
        !           118:   if (hp->next != NULL)
        !           119:     hp->next->prev = hp->prev;
        !           120: 
        !           121:   /* make sure that the bucket chain header that
        !           122:      the deleted guy was on points to the right thing afterwards. */
        !           123:   if (hp == *hp->bucket_hdr)
        !           124:     *hp->bucket_hdr = hp->next;
        !           125: 
        !           126:   if (hp->type == T_MACRO)
        !           127:     {
        !           128:       DEFINITION *d = hp->value.defn;
        !           129:       struct reflist *ap, *nextap;
        !           130: 
        !           131:       for (ap = d->pattern; ap != NULL; ap = nextap)
        !           132:        {
        !           133:          nextap = ap->next;
        !           134:          free (ap);
        !           135:        }
        !           136:       if (d->nargs >= 0)
        !           137:        free (d->args.argnames);
        !           138:       free (d);
        !           139:     }
        !           140: 
        !           141:   free (hp);
        !           142: }
        !           143: /*
        !           144:  * install a name in the main hash table, even if it is already there.
        !           145:  *   name stops with first non alphanumeric, except leading '#'.
        !           146:  * caller must check against redefinition if that is desired.
        !           147:  * delete_macro () removes things installed by install () in fifo order.
        !           148:  * this is important because of the `defined' special symbol used
        !           149:  * in #if, and also if pushdef/popdef directives are ever implemented.
        !           150:  *
        !           151:  * If LEN is >= 0, it is the length of the name.
        !           152:  * Otherwise, compute the length by scanning the entire name.
        !           153:  *
        !           154:  * If HASH is >= 0, it is the precomputed hash code.
        !           155:  * Otherwise, compute the hash code.
        !           156:  */
        !           157: HASHNODE *
        !           158: install (name, len, type, ivalue, value, hash)
        !           159:      U_CHAR *name;
        !           160:      int len;
        !           161:      enum node_type type;
        !           162:      int ivalue;
        !           163:      char *value;
        !           164:      int hash;
        !           165: {
        !           166:   register HASHNODE *hp;
        !           167:   register int i, bucket;
        !           168:   register U_CHAR *p, *q;
        !           169: 
        !           170:   if (len < 0) {
        !           171:     p = name;
        !           172:     while (is_idchar[*p])
        !           173:       p++;
        !           174:     len = p - name;
        !           175:   }
        !           176: 
        !           177:   if (hash < 0)
        !           178:     hash = hashf (name, len, HASHSIZE);
        !           179: 
        !           180:   i = sizeof (HASHNODE) + len + 1;
        !           181:   hp = (HASHNODE *) xmalloc (i);
        !           182:   bucket = hash;
        !           183:   hp->bucket_hdr = &hashtab[bucket];
        !           184:   hp->next = hashtab[bucket];
        !           185:   hashtab[bucket] = hp;
        !           186:   hp->prev = NULL;
        !           187:   if (hp->next != NULL)
        !           188:     hp->next->prev = hp;
        !           189:   hp->type = type;
        !           190:   hp->length = len;
        !           191:   if (hp->type == T_CONST)
        !           192:     hp->value.ival = ivalue;
        !           193:   else
        !           194:     hp->value.cpval = value;
        !           195:   hp->name = ((U_CHAR *) hp) + sizeof (HASHNODE);
        !           196:   p = hp->name;
        !           197:   q = name;
        !           198:   for (i = 0; i < len; i++)
        !           199:     *p++ = *q++;
        !           200:   hp->name[len] = 0;
        !           201:   return hp;
        !           202: }
        !           203: 
        !           204: void
        !           205: cpp_hash_cleanup (pfile)
        !           206:      cpp_reader *pfile;
        !           207: {
        !           208:   register int i;
        !           209:   for (i = HASHSIZE; --i >= 0; )
        !           210:     {
        !           211:       while (hashtab[i])
        !           212:        delete_macro (hashtab[i]);
        !           213:     }
        !           214: }

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