1 #include	"mk.h"
2 
3 static	Word		*subsub(Word*, char*, char*);
4 static	Word		*expandvar(char**);
5 static	Bufblock	*varname(char**);
6 static	Word		*extractpat(char*, char**, char*, char*);
7 static	int		submatch(char*, Word*, Word*, int*, char**);
8 static	Word		*varmatch(char *, char**);
9 
10 Word *
11 varsub(char **s)
12 {
13 	Bufblock *b;
14 	Word *w;
15 
16 	if(**s == '{')		/* either ${name} or ${name: A%B==C%D}*/
17 		return expandvar(s);
18 
19 	b = varname(s);
20 	if(b == 0)
21 		return 0;
22 
23 	w = varmatch(b->start, s);
24 	freebuf(b);
25 	return w;
26 }
27 
28 /*
29  *	extract a variable name
30  */
31 static Bufblock*
32 varname(char **s)
33 {
34 	Bufblock *b;
35 	char *cp;
36 	Rune r;
37 	int n;
38 
39 	b = newbuf();
40 	cp = *s;
41 	for(;;){
42 		n = chartorune(&r, cp);
43 		if (!WORDCHR(r))
44 			break;
45 		rinsert(b, r);
46 		cp += n;
47 	}
48 	if (b->current == b->start){
49 		SYNERR(-1);
50 		fprint(2, "missing variable name <%s>\n", *s);
51 		freebuf(b);
52 		return 0;
53 	}
54 	*s = cp;
55 	insert(b, 0);
56 	return b;
57 }
58 
59 static Word*
60 varmatch(char *name, char **s)
61 {
62 	Word *w;
63 	Symtab *sym;
64 	char *cp;
65 	
66 	sym = symlook(name, S_VAR, 0);
67 	if(sym){
68 			/* check for at least one non-NULL value */
69 		for (w = (Word*)sym->value; w; w = w->next)
70 			if(w->s && *w->s)
71 				return wdup(w);
72 	}
73 	for(cp = *s; *cp == ' ' || *cp == '\t'; cp++)	/* skip trailing whitespace */
74 			;
75 	*s = cp;
76 	return 0;
77 }
78 
79 static Word*
80 expandvar(char **s)
81 {
82 	Word *w;
83 	Bufblock *buf;
84 	Symtab *sym;
85 	char *cp, *begin, *end;
86 
87 	begin = *s;
88 	(*s)++;						/* skip the '{' */
89 	buf = varname(s);
90 	if (buf == 0)
91 		return 0;
92 	cp = *s;
93 	if (*cp == '}') {				/* ${name} variant*/
94 		(*s)++;					/* skip the '}' */
95 		w = varmatch(buf->start, s);
96 		freebuf(buf);
97 		return w;
98 	}
99 	if (*cp != ':') {
100 		SYNERR(-1);
101 		fprint(2, "bad variable name <%s>\n", buf->start);
102 		freebuf(buf);
103 		return 0;
104 	}
105 	cp++;
106 	end = shellt->charin(cp , "}");
107 	if(end == 0){
108 		SYNERR(-1);
109 		fprint(2, "missing '}': %s\n", begin);
110 		Exit();
111 	}
112 	*end = 0;
113 	*s = end+1;
114 	
115 	sym = symlook(buf->start, S_VAR, 0);
116 	if(sym == 0 || sym->value == 0)
117 		w = newword(buf->start);
118 	else
119 		w = subsub((Word*) sym->value, cp, end);
120 	freebuf(buf);
121 	return w;
122 }
123 
124 static Word*
125 extractpat(char *s, char **r, char *term, char *end)
126 {
127 	int save;
128 	char *cp;
129 	Word *w;
130 
131 	cp = shellt->charin(s, term);
132 	if(cp){
133 		*r = cp;
134 		if(cp == s)
135 			return 0;
136 		save = *cp;
137 		*cp = 0;
138 		w = stow(s);
139 		*cp = save;
140 	} else {
141 		*r = end;
142 		w = stow(s);
143 	}
144 	return w;
145 }
146 
147 static Word*
148 subsub(Word *v, char *s, char *end)
149 {
150 	int nmid;
151 	Word *head, *tail, *w, *h;
152 	Word *a, *b, *c, *d;
153 	Bufblock *buf;
154 	char *cp, *enda;
155 
156 	a = extractpat(s, &cp, "=%&", end);
157 	b = c = d = 0;
158 	if(PERCENT(*cp))
159 		b = extractpat(cp+1, &cp, "=", end);
160 	if(*cp == '=')
161 		c = extractpat(cp+1, &cp, "&%", end);
162 	if(PERCENT(*cp))
163 		d = stow(cp+1);
164 	else if(*cp)
165 		d = stow(cp);
166 
167 	head = tail = 0;
168 	buf = newbuf();
169 	for(; v; v = v->next){
170 		h = w = 0;
171 		if(submatch(v->s, a, b, &nmid, &enda)){
172 			/* enda points to end of A match in source;
173 			 * nmid = number of chars between end of A and start of B
174 			 */
175 			if(c){
176 				h = w = wdup(c);
177 				while(w->next)
178 					w = w->next;
179 			}
180 			if(PERCENT(*cp) && nmid > 0){	
181 				if(w){
182 					bufcpy(buf, w->s, strlen(w->s));
183 					bufcpy(buf, enda, nmid);
184 					insert(buf, 0);
185 					free(w->s);
186 					w->s = strdup(buf->start);
187 				} else {
188 					bufcpy(buf, enda, nmid);
189 					insert(buf, 0);
190 					h = w = newword(buf->start);
191 				}
192 				buf->current = buf->start;
193 			}
194 			if(d && *d->s){
195 				if(w){
196 
197 					bufcpy(buf, w->s, strlen(w->s));
198 					bufcpy(buf, d->s, strlen(d->s));
199 					insert(buf, 0);
200 					free(w->s);
201 					w->s = strdup(buf->start);
202 					w->next = wdup(d->next);
203 					while(w->next)
204 						w = w->next;
205 					buf->current = buf->start;
206 				} else
207 					h = w = wdup(d);
208 			}
209 		}
210 		if(w == 0)
211 			h = w = newword(v->s);
212 	
213 		if(head == 0)
214 			head = h;
215 		else
216 			tail->next = h;
217 		tail = w;
218 	}
219 	freebuf(buf);
220 	delword(a);
221 	delword(b);
222 	delword(c);
223 	delword(d);
224 	return head;
225 }
226 
227 static int
228 submatch(char *s, Word *a, Word *b, int *nmid, char **enda)
229 {
230 	Word *w;
231 	int n;
232 	char *end;
233 
234 	n = 0;
235 	for(w = a; w; w = w->next){
236 		n = strlen(w->s);
237 		if(strncmp(s, w->s, n) == 0)
238 			break;
239 	}
240 	if(a && w == 0)		/*  a == NULL matches everything*/
241 		return 0;
242 
243 	*enda = s+n;		/* pointer to end a A part match */
244 	*nmid = strlen(s)-n;	/* size of remainder of source */
245 	end = *enda+*nmid;
246 	for(w = b; w; w = w->next){
247 		n = strlen(w->s);
248 		if(strcmp(w->s, end-n) == 0){
249 			*nmid -= n;
250 			break;
251 		}
252 	}
253 	if(b && w == 0)		/* b == NULL matches everything */
254 		return 0;
255 	return 1;
256 }