1 /***********************************************************************
2 *                                                                      *
3 *               This software is part of the ast package               *
4 *          Copyright (c) 1985-2011 AT&T Intellectual Property          *
5 *                      and is licensed under the                       *
6 *                 Eclipse Public License, Version 1.0                  *
7 *                    by AT&T Intellectual Property                     *
8 *                                                                      *
9 *                A copy of the License is available at                 *
10 *          http://www.eclipse.org/org/documents/epl-v10.html           *
11 *         (with md5 checksum b35adb5213ca9657e911e9befb180842)         *
12 *                                                                      *
13 *              Information and Software Systems Research               *
14 *                            AT&T Research                             *
15 *                           Florham Park NJ                            *
16 *                                                                      *
17 *                 Glenn Fowler <gsf@research.att.com>                  *
18 *                  David Korn <dgk@research.att.com>                   *
19 *                   Phong Vo <kpv@research.att.com>                    *
20 *                                                                      *
21 ***********************************************************************/
22 #pragma prototyped
23 /*
24  * Glenn Fowler
25  * AT&T Research
26  *
27  * token stream routines
28  */
29 
30 #include <ast.h>
31 #include <tok.h>
32 
33 #define FLG_RESTORE	01		/* restore string on close	*/
34 #define FLG_NEWLINE	02		/* return newline token next	*/
35 
36 typedef struct Tok_s			/* token stream state		*/
37 {
38 	union
39 	{
40 	char*		end;		/* end ('\0') of last token	*/
41 	struct Tok_s*	nxt;		/* next in free list		*/
42 	}		ptr;
43 	char		chr;		/* replace *end with this	*/
44 	char		flg;		/* FLG_*			*/
45 } Tok_t;
46 
47 static Tok_t*		freelist;
48 
49 /*
50  * open a new token stream on s
51  * if f==0 then string is not restored
52  */
53 
54 char*
tokopen(register char * s,int f)55 tokopen(register char* s, int f)
56 {
57 	register Tok_t*	p;
58 
59 	if (p = freelist)
60 		freelist = freelist->ptr.nxt;
61 	else if (!(p = newof(0, Tok_t, 1, 0)))
62 		return 0;
63 	p->chr = *(p->ptr.end = s);
64 	p->flg = f ? FLG_RESTORE : 0;
65 	return (char*)p;
66 }
67 
68 /*
69  * close a token stream
70  * restore the string to its original state
71  */
72 
73 void
tokclose(char * u)74 tokclose(char* u)
75 {
76 	register Tok_t*	p = (Tok_t*)u;
77 
78 	if (p->flg == FLG_RESTORE && *p->ptr.end != p->chr)
79 		*p->ptr.end = p->chr;
80 	p->ptr.nxt = freelist;
81 	freelist = p;
82 }
83 
84 /*
85  * return next space separated token
86  * "\n" is returned as a token
87  * 0 returned when no tokens remain
88  * "..." and '...' quotes are honored with \ escapes
89  */
90 
91 char*
tokread(char * u)92 tokread(char* u)
93 {
94 	register Tok_t*	p = (Tok_t*)u;
95 	register char*	s;
96 	register char*	r;
97 	register int	q;
98 	register int	c;
99 
100 	/*
101 	 * restore string on each call
102 	 */
103 
104 	if (!p->chr)
105 		return 0;
106 	s = p->ptr.end;
107 	switch (p->flg)
108 	{
109 	case FLG_NEWLINE:
110 		p->flg = 0;
111 		return "\n";
112 	case FLG_RESTORE:
113 		if (*s != p->chr)
114 			*s = p->chr;
115 		break;
116 	default:
117 		if (!*s)
118 			s++;
119 		break;
120 	}
121 
122 	/*
123 	 * skip leading space
124 	 */
125 
126 	while (*s == ' ' || *s == '\t')
127 		s++;
128 	if (!*s)
129 	{
130 		p->ptr.end = s;
131 		p->chr = 0;
132 		return 0;
133 	}
134 
135 	/*
136 	 * find the end of this token
137 	 */
138 
139 	r = s;
140 	q = 0;
141 	for (;;)
142 		switch (c = *r++)
143 		{
144 		case '\n':
145 			if (!q)
146 			{
147 				if (s == (r - 1))
148 				{
149 					if (!p->flg)
150 					{
151 						p->ptr.end = r;
152 						return "\n";
153 					}
154 					r++;
155 				}
156 				else if (!p->flg)
157 					p->flg = FLG_NEWLINE;
158 			}
159 			/*FALLTHROUGH*/
160 		case ' ':
161 		case '\t':
162 			if (q)
163 				break;
164 			/*FALLTHROUGH*/
165 		case 0:
166 			if (s == --r)
167 			{
168 				p->ptr.end = r;
169 				p->chr = 0;
170 			}
171 			else
172 			{
173 				p->chr = *(p->ptr.end = r);
174 				if (*r)
175 					*r = 0;
176 			}
177 			return s;
178 		case '\\':
179 			if (*r)
180 				r++;
181 			break;
182 		case '"':
183 		case '\'':
184 			if (c == q)
185 				q = 0;
186 			else if (!q)
187 				q = c;
188 			break;
189 		}
190 }
191