sys/src/cmd/mk/varsub.c

   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 *);
   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);
  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)
  61 {
  62         Word *w;
  63         Symtab *sym;
  64
  65         sym = symlook(name, S_VAR, 0);
  66         if(sym){
  67                         /* check for at least one non-NULL value */
  68                 for (w = sym->u.ptr; w; w = w->next)
  69                         if(w->s && *w->s)
  70                                 return wdup(w);
  71         }
  72         return 0;
  73 }
  74
  75 static Word*
  76 expandvar(char **s)
  77 {
  78         Word *w;
  79         Bufblock *buf;
  80         Symtab *sym;
  81         char *cp, *begin, *end;
  82
  83         begin = *s;
  84         (*s)++;                                         /* skip the '{' */
  85         buf = varname(s);
  86         if (buf == 0)
  87                 return 0;
  88         cp = *s;
  89         if (*cp == '}') {                               /* ${name} variant*/
  90                 (*s)++;                                 /* skip the '}' */
  91                 w = varmatch(buf->start);
  92                 freebuf(buf);
  93                 return w;
  94         }
  95         if (*cp != ':') {
  96                 SYNERR(-1);
  97                 fprint(2, "bad variable name <%s>\n", buf->start);
  98                 freebuf(buf);
  99                 return 0;
 100         }
 101         cp++;
 102         end = charin(cp , "}");
 103         if(end == 0){
 104                 SYNERR(-1);
 105                 fprint(2, "missing '}': %s\n", begin);
 106                 Exit();
 107         }
 108         *end = 0;
 109         *s = end+1;
 110
 111         sym = symlook(buf->start, S_VAR, 0);
 112         if(sym == 0 || sym->u.value == 0)
 113                 w = newword(buf->start);
 114         else
 115                 w = subsub(sym->u.ptr, cp, end);
 116         freebuf(buf);
 117         return w;
 118 }
 119
 120 static Word*
 121 extractpat(char *s, char **r, char *term, char *end)
 122 {
 123         int save;
 124         char *cp;
 125         Word *w;
 126
 127         cp = charin(s, term);
 128         if(cp){
 129                 *r = cp;
 130                 if(cp == s)
 131                         return 0;
 132                 save = *cp;
 133                 *cp = 0;
 134                 w = stow(s);
 135                 *cp = save;
 136         } else {
 137                 *r = end;
 138                 w = stow(s);
 139         }
 140         return w;
 141 }
 142
 143 static Word*
 144 subsub(Word *v, char *s, char *end)
 145 {
 146         int nmid;
 147         Word *head, *tail, *w, *h;
 148         Word *a, *b, *c, *d;
 149         Bufblock *buf;
 150         char *cp, *enda;
 151
 152         a = extractpat(s, &cp, "=%&", end);
 153         b = c = d = 0;
 154         if(PERCENT(*cp))
 155                 b = extractpat(cp+1, &cp, "=", end);
 156         if(*cp == '=')
 157                 c = extractpat(cp+1, &cp, "&%", end);
 158         if(PERCENT(*cp))
 159                 d = stow(cp+1);
 160         else if(*cp)
 161                 d = stow(cp);
 162
 163         head = tail = 0;
 164         buf = newbuf();
 165         for(; v; v = v->next){
 166                 h = w = 0;
 167                 if(submatch(v->s, a, b, &nmid, &enda)){
 168                         /* enda points to end of A match in source;
 169                          * nmid = number of chars between end of A and start of B
 170                          */
 171                         if(c){
 172                                 h = w = wdup(c);
 173                                 while(w->next)
 174                                         w = w->next;
 175                         }
 176                         if(PERCENT(*cp) && nmid > 0){
 177                                 if(w){
 178                                         bufcpy(buf, w->s, strlen(w->s));
 179                                         bufcpy(buf, enda, nmid);
 180                                         insert(buf, 0);
 181                                         free(w->s);
 182                                         w->s = strdup(buf->start);
 183                                 } else {
 184                                         bufcpy(buf, enda, nmid);
 185                                         insert(buf, 0);
 186                                         h = w = newword(buf->start);
 187                                 }
 188                                 buf->current = buf->start;
 189                         }
 190                         if(d && *d->s){
 191                                 if(w){
 192
 193                                         bufcpy(buf, w->s, strlen(w->s));
 194                                         bufcpy(buf, d->s, strlen(d->s));
 195                                         insert(buf, 0);
 196                                         free(w->s);
 197                                         w->s = strdup(buf->start);
 198                                         w->next = wdup(d->next);
 199                                         while(w->next)
 200                                                 w = w->next;
 201                                         buf->current = buf->start;
 202                                 } else
 203                                         h = w = wdup(d);
 204                         }
 205                 }
 206                 if(w == 0)
 207                         h = w = newword(v->s);
 208
 209                 if(head == 0)
 210                         head = h;
 211                 else
 212                         tail->next = h;
 213                 tail = w;
 214         }
 215         freebuf(buf);
 216         delword(a);
 217         delword(b);
 218         delword(c);
 219         delword(d);
 220         return head;
 221 }
 222
 223 static int
 224 submatch(char *s, Word *a, Word *b, int *nmid, char **enda)
 225 {
 226         Word *w;
 227         int n;
 228         char *end;
 229
 230         n = 0;
 231         for(w = a; w; w = w->next){
 232                 n = strlen(w->s);
 233                 if(strncmp(s, w->s, n) == 0)
 234                         break;
 235         }
 236         if(a && w == 0)         /*  a == NULL matches everything*/
 237                 return 0;
 238
 239         *enda = s+n;            /* pointer to end a A part match */
 240         *nmid = strlen(s)-n;    /* size of remainder of source */
 241         end = *enda+*nmid;
 242         for(w = b; w; w = w->next){
 243                 n = strlen(w->s);
 244                 if(strcmp(w->s, end-n) == 0){
 245                         *nmid -= n;
 246                         break;
 247                 }
 248         }
 249         if(b && w == 0)         /* b == NULL matches everything */
 250                 return 0;
 251         return 1;
 252 }