Initial revision

src/cmd/mk/varsub.c

@@ -0,0 +1,256 @@
+#include	"mk.h"
+
+static	Word		*subsub(Word*, char*, char*);
+static	Word		*expandvar(char**);
+static	Bufblock	*varname(char**);
+static	Word		*extractpat(char*, char**, char*, char*);
+static	int		submatch(char*, Word*, Word*, int*, char**);
+static	Word		*varmatch(char *, char**);
+
+Word *
+varsub(char **s)
+{
+	Bufblock *b;
+	Word *w;
+
+	if(**s == '{')		/* either ${name} or ${name: A%B==C%D}*/
+		return expandvar(s);
+
+	b = varname(s);
+	if(b == 0)
+		return 0;
+
+	w = varmatch(b->start, s);
+	freebuf(b);
+	return w;
+}
+
+/*
+ *	extract a variable name
+ */
+static Bufblock*
+varname(char **s)
+{
+	Bufblock *b;
+	char *cp;
+	Rune r;
+	int n;
+
+	b = newbuf();
+	cp = *s;
+	for(;;){
+		n = chartorune(&r, cp);
+		if (!WORDCHR(r))
+			break;
+		rinsert(b, r);
+		cp += n;
+	}
+	if (b->current == b->start){
+		SYNERR(-1);
+		fprint(2, "missing variable name <%s>\n", *s);
+		freebuf(b);
+		return 0;
+	}
+	*s = cp;
+	insert(b, 0);
+	return b;
+}
+
+static Word*
+varmatch(char *name, char **s)
+{
+	Word *w;
+	Symtab *sym;
+	char *cp;
+	
+	sym = symlook(name, S_VAR, 0);
+	if(sym){
+			/* check for at least one non-NULL value */
+		for (w = (Word*)sym->value; w; w = w->next)
+			if(w->s && *w->s)
+				return wdup(w);
+	}
+	for(cp = *s; *cp == ' ' || *cp == '\t'; cp++)	/* skip trailing whitespace */
+			;
+	*s = cp;
+	return 0;
+}
+
+static Word*
+expandvar(char **s)
+{
+	Word *w;
+	Bufblock *buf;
+	Symtab *sym;
+	char *cp, *begin, *end;
+
+	begin = *s;
+	(*s)++;						/* skip the '{' */
+	buf = varname(s);
+	if (buf == 0)
+		return 0;
+	cp = *s;
+	if (*cp == '}') {				/* ${name} variant*/
+		(*s)++;					/* skip the '}' */
+		w = varmatch(buf->start, s);
+		freebuf(buf);
+		return w;
+	}
+	if (*cp != ':') {
+		SYNERR(-1);
+		fprint(2, "bad variable name <%s>\n", buf->start);
+		freebuf(buf);
+		return 0;
+	}
+	cp++;
+	end = charin(cp , "}");
+	if(end == 0){
+		SYNERR(-1);
+		fprint(2, "missing '}': %s\n", begin);
+		Exit();
+	}
+	*end = 0;
+	*s = end+1;
+	
+	sym = symlook(buf->start, S_VAR, 0);
+	if(sym == 0 || sym->value == 0)
+		w = newword(buf->start);
+	else
+		w = subsub((Word*) sym->value, cp, end);
+	freebuf(buf);
+	return w;
+}
+
+static Word*
+extractpat(char *s, char **r, char *term, char *end)
+{
+	int save;
+	char *cp;
+	Word *w;
+
+	cp = charin(s, term);
+	if(cp){
+		*r = cp;
+		if(cp == s)
+			return 0;
+		save = *cp;
+		*cp = 0;
+		w = stow(s);
+		*cp = save;
+	} else {
+		*r = end;
+		w = stow(s);
+	}
+	return w;
+}
+
+static Word*
+subsub(Word *v, char *s, char *end)
+{
+	int nmid;
+	Word *head, *tail, *w, *h;
+	Word *a, *b, *c, *d;
+	Bufblock *buf;
+	char *cp, *enda;
+
+	a = extractpat(s, &cp, "=%&", end);
+	b = c = d = 0;
+	if(PERCENT(*cp))
+		b = extractpat(cp+1, &cp, "=", end);
+	if(*cp == '=')
+		c = extractpat(cp+1, &cp, "&%", end);
+	if(PERCENT(*cp))
+		d = stow(cp+1);
+	else if(*cp)
+		d = stow(cp);
+
+	head = tail = 0;
+	buf = newbuf();
+	for(; v; v = v->next){
+		h = w = 0;
+		if(submatch(v->s, a, b, &nmid, &enda)){
+			/* enda points to end of A match in source;
+			 * nmid = number of chars between end of A and start of B
+			 */
+			if(c){
+				h = w = wdup(c);
+				while(w->next)
+					w = w->next;
+			}
+			if(PERCENT(*cp) && nmid > 0){	
+				if(w){
+					bufcpy(buf, w->s, strlen(w->s));
+					bufcpy(buf, enda, nmid);
+					insert(buf, 0);
+					free(w->s);
+					w->s = strdup(buf->start);
+				} else {
+					bufcpy(buf, enda, nmid);
+					insert(buf, 0);
+					h = w = newword(buf->start);
+				}
+				buf->current = buf->start;
+			}
+			if(d && *d->s){
+				if(w){
+
+					bufcpy(buf, w->s, strlen(w->s));
+					bufcpy(buf, d->s, strlen(d->s));
+					insert(buf, 0);
+					free(w->s);
+					w->s = strdup(buf->start);
+					w->next = wdup(d->next);
+					while(w->next)
+						w = w->next;
+					buf->current = buf->start;
+				} else
+					h = w = wdup(d);
+			}
+		}
+		if(w == 0)
+			h = w = newword(v->s);
+	
+		if(head == 0)
+			head = h;
+		else
+			tail->next = h;
+		tail = w;
+	}
+	freebuf(buf);
+	delword(a);
+	delword(b);
+	delword(c);
+	delword(d);
+	return head;
+}
+
+static int
+submatch(char *s, Word *a, Word *b, int *nmid, char **enda)
+{
+	Word *w;
+	int n;
+	char *end;
+
+	n = 0;
+	for(w = a; w; w = w->next){
+		n = strlen(w->s);
+		if(strncmp(s, w->s, n) == 0)
+			break;
+	}
+	if(a && w == 0)		/*  a == NULL matches everything*/
+		return 0;
+
+	*enda = s+n;		/* pointer to end a A part match */
+	*nmid = strlen(s)-n;	/* size of remainder of source */
+	end = *enda+*nmid;
+	for(w = b; w; w = w->next){
+		n = strlen(w->s);
+		if(strcmp(w->s, end-n) == 0){
+			*nmid -= n;
+			break;
+		}
+	}
+	if(b && w == 0)		/* b == NULL matches everything */
+		return 0;
+	return 1;
+}