ref: faa625a1d5ab47ac0438b2cea5b2bde1ea747b8b
dir: /sys/src/cmd/mk/varsub.c/
#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 *); 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); 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) { Word *w; Symtab *sym; sym = symlook(name, S_VAR, 0); if(sym){ /* check for at least one non-NULL value */ for (w = sym->u.ptr; w; w = w->next) if(w->s && *w->s) return wdup(w); } 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); 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->u.value == 0) w = newword(buf->start); else w = subsub(sym->u.ptr, 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; }