flex-2.5.33/examples/debflex.awk

   1 # Clarify the flex debug trace by substituting first line of each rule.
   2 # Francois Pinard <pinard@iro.umontreal.ca>, July 1990.
   3 #
   4 # Rewritten to process correctly \n's in scanner input.
   5 # BEGIN section modified to correct a collection of rules.
   6 # Michal Jaegermann <michal@phys.ualberta.ca>, December 1993
   7 #
   8 # Sample usage:
   9 #       flex -d PROGRAM.l
  10 #       gcc -o PROGRAM PROGRAM.c -lfl
  11 #       PROGRAM 2>&1 | gawk -f debflex.awk PROGRAM.l
  12 #
  13 # (VP's note: this script presently does not work with either "old" or
  14 #  "new" awk; fixes so it does will be welcome)
  15
  16 BEGIN {
  17     # Insure proper usage.
  18
  19     if (ARGC != 2) {
  20         print "usage: gawk -f debflex.awk FLEX_SOURCE <DEBUG_OUTPUT";
  21         exit (1);
  22     }
  23
  24     # Remove and save the name of flex source.
  25
  26     source = ARGV[1];
  27     ARGC--;
  28
  29     # Swallow the flex source file.
  30
  31     line = 0;
  32     section = 1;
  33     while (getline <source) {
  34
  35         # Count the lines.
  36
  37         line++;
  38
  39         # Count the sections.  When encountering section 3,
  40         # break out of the awk BEGIN block.
  41
  42         if (match ($0, /^%%/)) {
  43             section++;
  44             if (section == 3) {
  45                 break;
  46             }
  47         }
  48         else {
  49             # Only the lines in section 2 which do not begin in a
  50             # tab or space might be referred to by the flex debug
  51             # trace.  Save only those lines.
  52
  53             if (section == 2 && match ($0, /^[^ \t]/)) {
  54                 rules[line] = $0;
  55             }
  56         }
  57     }
  58     dashes = "-----------------------------------------------------------";
  59     collect = "";
  60     line = 0;
  61 }
  62
  63 # collect complete rule output from a scanner
  64 $0 !~ /^--/ {
  65     collect = collect "\n" $0;
  66     next;
  67 }
  68 # otherwise we have a new rule - process what we got so far
  69 {
  70     process();
  71 }
  72 # and the same thing if we hit EOF
  73 END {
  74     process();
  75 }
  76
  77 function process() {
  78
  79     # splitting this way we loose some double dashes and
  80     # left parentheses from echoed input - a small price to pay
  81     n = split(collect, field, "\n--|[(]");
  82
  83     # this loop kicks in only when we already collected something
  84     for (i = 1; i <= n; i++) {
  85         if (0 != line) {
  86             # we do not care for traces of newlines.
  87             if (0 == match(field[i], /\"\n+\"[)]/)) {
  88                 if (rules[line]) {
  89                     text = field[i];
  90                     while ( ++i <= n) {
  91                         text = text field[i];
  92                     }
  93                     printf("%s:%d: %-8s -- %s\n",
  94                            source, line, text, rules[line]);
  95                 }
  96                 else {
  97                     print;
  98                     printf "%s:%d: *** No such rule.\n", source, line;
  99                 }
 100             }
 101             line = 0;
 102             break;
 103         }
 104         if ("" != field[i]) {
 105             if ("end of buffer or a NUL)" == field[i]) {
 106                 print dashes;  # Simplify trace of buffer reloads
 107                 continue;
 108             }
 109             if (match(field[i], /accepting rule at line /)) {
 110                 # force interpretation of line as a number
 111                 line = 0 + substr(field[i], RLENGTH);
 112                 continue;
 113             }
 114             # echo everything else
 115             printf("--%s\n", field[i]);
 116         }
 117     }
 118     collect = "\n" $0;  # ... and start next trace
 119 }