1 files changed, 119 insertions, 0 deletions
diff --git a/examples/debflex.awk b/examples/debflex.awk
new file mode 100644
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+# Clarify the flex debug trace by substituting first line of each rule.
+# Francois Pinard <pinard@iro.umontreal.ca>, July 1990.
+#
+# Rewritten to process correctly \n's in scanner input.
+# BEGIN section modified to correct a collection of rules.
+# Michal Jaegermann <michal@phys.ualberta.ca>, December 1993
+#
+# Sample usage:
+#	flex -d PROGRAM.l
+#	gcc -o PROGRAM PROGRAM.c -lfl
+#	PROGRAM 2>&1 | gawk -f debflex.awk PROGRAM.l
+#
+# (VP's note: this script presently does not work with either "old" or
+#  "new" awk; fixes so it does will be welcome)
+
+BEGIN {
+    # Insure proper usage.
+
+    if (ARGC != 2) {
+	print "usage: gawk -f debflex.awk FLEX_SOURCE <DEBUG_OUTPUT";
+	exit (1);
+    }
+
+    # Remove and save the name of flex source.
+
+    source = ARGV[1];
+    ARGC--;
+
+    # Swallow the flex source file.
+
+    line = 0;
+    section = 1;
+    while (getline <source) {
+
+	# Count the lines.
+
+	line++;
+
+	# Count the sections.  When encountering section 3,
+	# break out of the awk BEGIN block.
+
+	if (match ($0, /^%%/)) {
+	    section++;
+	    if (section == 3) {
+		break;
+	    }
+	}
+	else {
+	    # Only the lines in section 2 which do not begin in a
+	    # tab or space might be referred to by the flex debug
+	    # trace.  Save only those lines.
+
+	    if (section == 2 && match ($0, /^[^ \t]/)) {
+		rules[line] = $0;
+	    }
+	}
+    }
+    dashes = "-----------------------------------------------------------";
+    collect = "";
+    line = 0;
+}
+
+# collect complete rule output from a scanner
+$0 !~ /^--/ {
+    collect = collect "\n" $0;
+    next;
+}
+# otherwise we have a new rule - process what we got so far
+{
+    process();
+}
+# and the same thing if we hit EOF
+END {
+    process();
+}
+
+function process() {
+
+    # splitting this way we loose some double dashes and
+    # left parentheses from echoed input - a small price to pay
+    n = split(collect, field, "\n--|[(]");
+
+    # this loop kicks in only when we already collected something
+    for (i = 1; i <= n; i++) {
+	if (0 != line) {
+	    # we do not care for traces of newlines.
+	    if (0 == match(field[i], /\"\n+\"[)]/)) {
+		if (rules[line]) {
+		    text = field[i];
+		    while ( ++i <= n) {
+			text = text field[i];
+		    }
+		    printf("%s:%d: %-8s -- %s\n",
+			   source, line, text, rules[line]);
+		}
+		else {
+		    print;
+		    printf "%s:%d: *** No such rule.\n", source, line;
+		}
+	    }
+	    line = 0;
+	    break;
+	}
+	if ("" != field[i]) {
+	    if ("end of buffer or a NUL)" == field[i]) {
+		print dashes;  # Simplify trace of buffer reloads
+		continue;
+	    }
+	    if (match(field[i], /accepting rule at line /)) {
+		# force interpretation of line as a number
+		line = 0 + substr(field[i], RLENGTH);
+		continue;
+	    }
+	    # echo everything else
+	    printf("--%s\n", field[i]);
+	}
+    }
+    collect = "\n" $0;  # ... and start next trace
+}