implement multiple regex support and icase and negate flags

tablizer.pod

@@ -5,7 +5,7 @@ tablizer - Manipulate tabular output of other programs
 =head1 SYNOPSIS
 
     Usage:
-      tablizer [regex] [file, ...] [flags]
+      tablizer [regex,...] [file, ...] [flags]
     
     Operational Flags:
       -c, --columns string              Only show the speficied columns (separated by ,)
@@ -142,32 +142,44 @@ useful for the developer.
 
 =head2 PATTERNS AND FILTERING
 
-You can reduce the rows being  displayed by using a regular expression
-pattern.  The  regexp is  PCRE compatible, refer  to the  syntax cheat
-sheet here: L<https://github.com/google/re2/wiki/Syntax>.  If you want
-to read  a more comprehensive  documentation about the topic  and have
-perl installed you can read it with:
+You can reduce  the rows being displayed by using  one or more regular
+expression patterns.   The regexp  language being used  is the  one of
+GOLANG,     refer    to     the    syntax     cheat    sheet     here:
+L<https://pkg.go.dev/regexp/syntax>.
+
+If you  want to  read a more  comprehensive documentation  about the
+topic and have perl installed you can read it with:
 
     perldoc perlre
 
-Or read it online: L<https://perldoc.perl.org/perlre>.
+Or read it online: L<https://perldoc.perl.org/perlre>. But please note
+that the GO regexp engine does NOT support all perl regex terms,
+especially look-ahead and look-behind.
 
-A note on  modifiers: the regexp engine used in  tablizer uses another
-modifier syntax:
+If you want to supply flags to a regex, then surround it with slashes
+and append the flag. The following flags are supported:
 
-    (?MODIFIER)
-
-The most important modifiers are:
-
-C<i> ignore case
-C<m> multiline mode
-C<s> single line mode
+    i => case insensitive
+    ! => negative match
 
 Example for a case insensitive search:
 
-    kubectl get pods -A | tablizer "(?i)account"
+    kubectl get pods -A | tablizer "/account/i"
 
-You  can use  the experimental  fuzzy search  feature by  providing the
+If you use the C<!> flag, then the regex match will be negated, that
+is, if a line in the input matches the given regex, but C<!> is
+supplied, tablizer will NOT include it in the output.
+
+For example, here we want to get all lines matching "foo" but not
+"bar":
+
+    cat table | tablizer foo '/bar/!'
+
+This would match a line "foo zorro" but not "foo bar".
+
+The flags can also be combined.
+
+You  can also use  the experimental  fuzzy search  feature by  providing the
 option B<-z>, in which case the  pattern is regarded as a fuzzy search
 term, not a regexp.