parse.c revision a6ce1349539f866334ef3d5758bc2ee44a454acd 
1/*
2 * Copyright 1987, 1988 by MIT Student Information Processing Board
3 *
4 * Permission to use, copy, modify, and distribute this software and
5 * its documentation for any purpose is hereby granted, provided that
6 * the names of M.I.T. and the M.I.T. S.I.P.B. not be used in
7 * advertising or publicity pertaining to distribution of the software
8 * without specific, written prior permission.  M.I.T. and the
9 * M.I.T. S.I.P.B. make no representations about the suitability of
10 * this software for any purpose.  It is provided "as is" without
11 * express or implied warranty.
12 */
13
14#ifdef HAS_STDLIB_H
15#include <stdlib.h>
16#endif
17#include <string.h>
18#ifdef HAVE_ERRNO_H
19#include <errno.h>
20#endif
21
22#include "ss_internal.h"
23
24enum parse_mode { WHITESPACE, TOKEN, QUOTED_STRING };
25
26/*
27 * parse(line_ptr, argc_ptr)
28 *
29 * Function:
30 *      Parses line, dividing at whitespace, into tokens, returns
31 *      the "argc" and "argv" values.
32 * Arguments:
33 *      line_ptr (char *)
34 *              Pointer to text string to be parsed.
35 *      argc_ptr (int *)
36 *              Where to put the "argc" (number of tokens) value.
37 * Returns:
38 *      argv (char **)
39 *              Series of pointers to parsed tokens.
40 */
41
42#define NEW_ARGV(old,n) (char **)realloc((char *)old,\
43					 (unsigned)(n+2)*sizeof(char*))
44
45char **ss_parse (sci_idx, line_ptr, argc_ptr)
46    int sci_idx;
47    register char *line_ptr;
48    int *argc_ptr;
49{
50    register char **argv, *cp;
51    register int argc;
52    register enum parse_mode parse_mode;
53
54    argv = (char **) malloc (sizeof(char *));
55    if (argv == (char **)NULL) {
56	ss_error(sci_idx, errno, "Can't allocate storage");
57	*argc_ptr = 0;
58	return(argv);
59    }
60    *argv = (char *)NULL;
61
62    argc = 0;
63
64    parse_mode = WHITESPACE;	/* flushing whitespace */
65    cp = line_ptr;		/* cp is for output */
66    while (1) {
67#ifdef DEBUG
68	{
69	    printf ("character `%c', mode %d\n", *line_ptr, parse_mode);
70	}
71#endif
72	while (parse_mode == WHITESPACE) {
73	    if (*line_ptr == '\0')
74		goto end_of_line;
75	    if (*line_ptr == ' ' || *line_ptr == '\t') {
76		line_ptr++;
77		continue;
78	    }
79	    if (*line_ptr == '"') {
80		/* go to quoted-string mode */
81		parse_mode = QUOTED_STRING;
82		cp = line_ptr++;
83		argv = NEW_ARGV (argv, argc);
84		argv[argc++] = cp;
85		argv[argc] = NULL;
86	    }
87	    else {
88		/* random-token mode */
89		parse_mode = TOKEN;
90		cp = line_ptr;
91		argv = NEW_ARGV (argv, argc);
92		argv[argc++] = line_ptr;
93		argv[argc] = NULL;
94	    }
95	}
96	while (parse_mode == TOKEN) {
97	    if (*line_ptr == '\0') {
98		*cp++ = '\0';
99		goto end_of_line;
100	    }
101	    else if (*line_ptr == ' ' || *line_ptr == '\t') {
102		*cp++ = '\0';
103		line_ptr++;
104		parse_mode = WHITESPACE;
105	    }
106	    else if (*line_ptr == '"') {
107		line_ptr++;
108		parse_mode = QUOTED_STRING;
109	    }
110	    else {
111		*cp++ = *line_ptr++;
112	    }
113	}
114	while (parse_mode == QUOTED_STRING) {
115	    if (*line_ptr == '\0') {
116		ss_error (sci_idx, 0,
117			  "Unbalanced quotes in command line");
118		free (argv);
119		*argc_ptr = 0;
120		return NULL;
121	    }
122	    else if (*line_ptr == '"') {
123		if (*++line_ptr == '"') {
124		    *cp++ = '"';
125		    line_ptr++;
126		}
127		else {
128		    parse_mode = TOKEN;
129		}
130	    }
131	    else {
132		*cp++ = *line_ptr++;
133	    }
134	}
135    }
136end_of_line:
137    *argc_ptr = argc;
138#ifdef DEBUG
139    {
140	int i;
141	printf ("argc = %d\n", argc);
142	for (i = 0; i <= argc; i++)
143	    printf ("\targv[%2d] = `%s'\n", i,
144		    argv[i] ? argv[i] : "<NULL>");
145    }
146#endif
147    return(argv);
148}
149