Implement comment lines in subject strings in pcre2test (and perltest.sh) input files.

ChangeLog

@@ -184,6 +184,9 @@ is specified, a valgrind suppressions file is set up to ignore "Invalid read of
 size 16" errors because these are false positives when the hardware supports
 the SSE2 instruction set.
 
+52. It is now possible to have comment lines amid the subject strings in 
+pcre2test (and perltest.sh) input.
+
 
 Version 10.20 30-June-2015
 --------------------------

doc/pcre2test.1

@@ -1,4 +1,4 @@
-.TH PCRE2TEST 1 "12 September 2015" "PCRE 10.21"
+.TH PCRE2TEST 1 "14 September 2015" "PCRE 10.21"
 .SH NAME
 pcre2test - a program for testing Perl-compatible regular expressions.
 .SH SYNOPSIS
@@ -443,6 +443,12 @@ the start of a modifier list. For example:
 .sp
   abc\e=notbol,notempty
 .sp
+If the subject string is empty and \e= is followed by whitespace, the line is 
+treated as a comment line, and is not used for matching. For example:
+.sp
+  \e= This is a comment.
+  abc\e= This is an invalid modifier list.
+.sp    
 A backslash followed by any other non-alphanumeric character just escapes that
 character. A backslash followed by anything else causes an error. However, if
 the very last character in the line is a backslash (and there is no modifier
@@ -1519,6 +1525,6 @@ Cambridge, England.
 .rs
 .sp
 .nf
-Last updated: 12 September 2015
+Last updated: 14 September 2015
 Copyright (c) 1997-2015 University of Cambridge.
 .fi

perltest.sh

@@ -210,6 +210,8 @@ for (;;)
     s/^\s+//;  # Remove leading space
 
     last if ($_ eq "");
+    next if $_ =~ /^\\=(?:\s|$)/;   # Comment line
+ 
     $x = eval "\"$_\"";   # To get escapes processed
 
     # Empty array for holding results, ensure $REGERROR and $REGMARK are

src/pcre2test.c

@@ -6975,7 +6975,8 @@ while (notdone)
       skipping = FALSE;
       setlocale(LC_CTYPE, "C");
       }
-    else if (!skipping) rc = process_data();
+    else if (!skipping && !(p[0] == '\\' && p[1] == '=' && isspace(p[2]))) 
+      rc = process_data();
     }
 
   /* We do not have a pattern set up for testing. Lines starting with # are