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Annotation of 42BSD/ucb/dbx/keywords.c, revision 1.1

1.1     ! root        1: /* Copyright (c) 1982 Regents of the University of California */
        !             2: 
        !             3: static char sccsid[] = "@(#)keywords.c 1.3 5/18/83";
        !             4: 
        !             5: /*
        !             6:  * Keyword management.
        !             7:  */
        !             8: 
        !             9: #include "defs.h"
        !            10: #include "keywords.h"
        !            11: #include "scanner.h"
        !            12: #include "names.h"
        !            13: #include "symbols.h"
        !            14: #include "tree.h"
        !            15: #include "y.tab.h"
        !            16: 
        !            17: #ifndef public
        !            18: #include "scanner.h"
        !            19: #endif
        !            20: 
        !            21: private String reserved[] ={
        !            22:     "alias", "and", "assign", "at", "call", "catch", "cont",
        !            23:     "debug", "delete", "div", "dump", "edit", "file", "func",
        !            24:     "gripe", "help", "if", "ignore", "in",
        !            25:     "list", "mod", "next", "nexti", "nil", "not", "or",
        !            26:     "print", "psym", "quit", "run",
        !            27:     "sh", "skip", "source", "status", "step", "stepi",
        !            28:     "stop", "stopi", "trace", "tracei",
        !            29:     "use", "whatis", "when", "where", "whereis", "which",
        !            30:     "INT", "REAL", "NAME", "STRING",
        !            31:     "LFORMER", "RFORMER", "#^", "->"
        !            32: };
        !            33: 
        !            34: /*
        !            35:  * The keyword table is a traditional hash table with collisions
        !            36:  * resolved by chaining.
        !            37:  */
        !            38: 
        !            39: #define HASHTABLESIZE 503
        !            40: 
        !            41: typedef struct Keyword {
        !            42:     Name name;
        !            43:     Token toknum : 16;
        !            44:     Boolean isalias : 16;
        !            45:     struct Keyword *chain;
        !            46: } *Keyword;
        !            47: 
        !            48: typedef unsigned int Hashvalue;
        !            49: 
        !            50: private Keyword hashtab[HASHTABLESIZE];
        !            51: 
        !            52: #define hash(n) ((((unsigned) n) >> 2) mod HASHTABLESIZE)
        !            53: 
        !            54: /*
        !            55:  * Enter all the reserved words into the keyword table.
        !            56:  */
        !            57: 
        !            58: public enterkeywords()
        !            59: {
        !            60:     register Integer i;
        !            61: 
        !            62:     for (i = ALIAS; i <= WHICH; i++) {
        !            63:        keyword(reserved[ord(i) - ord(ALIAS)], i, false);
        !            64:     }
        !            65:     keyword("set", ASSIGN, false);
        !            66: }
        !            67: 
        !            68: /*
        !            69:  * Deallocate the keyword table.
        !            70:  */
        !            71: 
        !            72: public keywords_free()
        !            73: {
        !            74:     register Integer i;
        !            75:     register Keyword k, nextk;
        !            76: 
        !            77:     for (i = 0; i < HASHTABLESIZE; i++) {
        !            78:        k = hashtab[i];
        !            79:        while (k != nil) {
        !            80:            nextk = k->chain;
        !            81:            dispose(k);
        !            82:            k = nextk;
        !            83:        }
        !            84:        hashtab[i] = nil;
        !            85:     }
        !            86: }
        !            87: 
        !            88: /*
        !            89:  * Enter a keyword into the name table.  It is assumed to not be there already.
        !            90:  * The string is assumed to be statically allocated.
        !            91:  */
        !            92: 
        !            93: private keyword(s, t, isalias)
        !            94: String s;
        !            95: Token t;
        !            96: Boolean isalias;
        !            97: {
        !            98:     register Hashvalue h;
        !            99:     register Keyword k;
        !           100:     Name n;
        !           101: 
        !           102:     n = identname(s, true);
        !           103:     h = hash(n);
        !           104:     k = new(Keyword);
        !           105:     k->name = n;
        !           106:     k->toknum = t;
        !           107:     k->isalias = isalias;
        !           108:     k->chain = hashtab[h];
        !           109:     hashtab[h] = k;
        !           110: }
        !           111: 
        !           112: /*
        !           113:  * Return the string associated with a token corresponding to a keyword.
        !           114:  */
        !           115: 
        !           116: public String keywdstring(t)
        !           117: Token t;
        !           118: {
        !           119:     return reserved[ord(t) - ord(ALIAS)];
        !           120: }
        !           121: 
        !           122: /*
        !           123:  * Find a keyword in the keyword table.
        !           124:  * We assume that tokens cannot legitimately be nil (0).
        !           125:  */
        !           126: 
        !           127: public Token findkeyword(n)
        !           128: Name n;
        !           129: {
        !           130:     register Hashvalue h;
        !           131:     register Keyword k;
        !           132:     Token t;
        !           133: 
        !           134:     h = hash(n);
        !           135:     k = hashtab[h];
        !           136:     while (k != nil and k->name != n) {
        !           137:        k = k->chain;
        !           138:     }
        !           139:     if (k == nil) {
        !           140:        t = nil;
        !           141:     } else {
        !           142:        t = k->toknum;
        !           143:     }
        !           144:     return t;
        !           145: }
        !           146: 
        !           147: /*
        !           148:  * Create an alias.
        !           149:  */
        !           150: 
        !           151: public enter_alias(newcmd, oldcmd)
        !           152: Name newcmd;
        !           153: Name oldcmd;
        !           154: {
        !           155:     Token t;
        !           156: 
        !           157:     t = findkeyword(oldcmd);
        !           158:     if (t == nil) {
        !           159:        error("\"%s\" is not a command", ident(oldcmd));
        !           160:     } else {
        !           161:        keyword(ident(newcmd), t, true);
        !           162:     }
        !           163: }
        !           164: 
        !           165: /*
        !           166:  * Print out an alias.
        !           167:  */
        !           168: 
        !           169: public print_alias(cmd)
        !           170: Name cmd;
        !           171: {
        !           172:     register Keyword k;
        !           173:     register Integer i;
        !           174:     Token t;
        !           175: 
        !           176:     if (cmd == nil) {
        !           177:        for (i = 0; i < HASHTABLESIZE; i++) {
        !           178:            for (k = hashtab[i]; k != nil; k = k->chain) {
        !           179:                if (k->isalias) {
        !           180:                    if (isredirected()) {
        !           181:                        printf("alias ");
        !           182:                    }
        !           183:                    printf("%s\t%s\n", ident(k->name), keywdstring(k->toknum));
        !           184:                }
        !           185:            }
        !           186:        }
        !           187:     } else {
        !           188:        t = findkeyword(cmd);
        !           189:        if (t == nil) {
        !           190:            printf("\n");
        !           191:        } else {
        !           192:            printf("%s\n", keywdstring(t));
        !           193:        }
        !           194:     }
        !           195: }

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