sys/src/cmd/mk/lex.c

   1 #include        "mk.h"
   2
   3 static  int     bquote(Biobuf*, Bufblock*);
   4
   5 /*
   6  *      Assemble a line skipping blank lines, comments, and eliding
   7  *      escaped newlines
   8  */
   9 int
  10 assline(Biobuf *bp, Bufblock *buf)
  11 {
  12         int c;
  13         int lastc;
  14
  15         buf->current=buf->start;
  16         while ((c = nextrune(bp, 1)) >= 0){
  17                 switch(c)
  18                 {
  19                 case '\r':              /* consumes CRs for Win95 */
  20                         continue;
  21                 case '\n':
  22                         if (buf->current != buf->start) {
  23                                 insert(buf, 0);
  24                                 return 1;
  25                         }
  26                         break;          /* skip empty lines */
  27                 case '\\':
  28                 case '\'':
  29                 case '"':
  30                         rinsert(buf, c);
  31                         if (escapetoken(bp, buf, 1, c) == 0)
  32                                 Exit();
  33                         break;
  34                 case '`':
  35                         if (bquote(bp, buf) == 0)
  36                                 Exit();
  37                         break;
  38                 case '#':
  39                         lastc = '#';
  40                         while ((c = Bgetc(bp)) != '\n') {
  41                                 if (c < 0)
  42                                         goto eof;
  43                                 if(c != '\r')
  44                                         lastc = c;
  45                         }
  46                         mkinline++;
  47                         if (lastc == '\\')
  48                                 break;          /* propagate escaped newlines??*/
  49                         if (buf->current != buf->start) {
  50                                 insert(buf, 0);
  51                                 return 1;
  52                         }
  53                         break;
  54                 default:
  55                         rinsert(buf, c);
  56                         break;
  57                 }
  58         }
  59 eof:
  60         insert(buf, 0);
  61         return *buf->start != 0;
  62 }
  63
  64 /*
  65  *      assemble a back-quoted shell command into a buffer
  66  */
  67 static int
  68 bquote(Biobuf *bp, Bufblock *buf)
  69 {
  70         int c, line, term, depth;
  71         int start;
  72
  73         line = mkinline;
  74         while((c = Bgetrune(bp)) == ' ' || c == '\t')
  75                         ;
  76         if(c == '{'){
  77                 term = '}';             /* rc style */
  78                 while((c = Bgetrune(bp)) == ' ' || c == '\t')
  79                         ;
  80         } else
  81                 term = '`';             /* sh style */
  82
  83         depth = 1;
  84         start = buf->current-buf->start;
  85         for(;c > 0; c = nextrune(bp, 0)){
  86                 if(c == '{' && term == '}')
  87                         depth++;
  88                 if(c == term && --depth == 0){
  89                         insert(buf, '\n');
  90                         insert(buf,0);
  91                         buf->current = buf->start+start;
  92                         execinit();
  93                         execsh(0, buf->current, buf, envy);
  94                         return 1;
  95                 }
  96                 if(c == '\n')
  97                         break;
  98                 if(c == '\'' || c == '"' || c == '\\'){
  99                         insert(buf, c);
 100                         if(!escapetoken(bp, buf, 1, c))
 101                                 return 0;
 102                         continue;
 103                 }
 104                 rinsert(buf, c);
 105         }
 106         SYNERR(line);
 107         fprint(2, "missing closing %c after `\n", term);
 108         return 0;
 109 }
 110
 111 /*
 112  *      get next character stripping escaped newlines
 113  *      the flag specifies whether escaped newlines are to be elided or
 114  *      replaced with a blank.
 115  */
 116 int
 117 nextrune(Biobuf *bp, int elide)
 118 {
 119         int c;
 120
 121         for (;;) {
 122                 c = Bgetrune(bp);
 123                 if (c == '\\') {
 124                         if (Bgetrune(bp) == '\n') {
 125                                 mkinline++;
 126                                 if (elide)
 127                                         continue;
 128                                 return ' ';
 129                         }
 130                         Bungetrune(bp);
 131                 }
 132                 if (c == '\n')
 133                         mkinline++;
 134                 return c;
 135         }
 136 }