1 #! /usr/bin/perl

     2 use 5.014;

     3 use strict;

     4 use warnings;

     5 use List::MoreUtils qw(uniq);

     6 

     7 my $what = shift // die "$0: Usage {main} [spec.xfpt]\n";

     8 

     9 @ARGV = "$ENV{HOME}/src/exim/doc/doc-docbook/spec.xfpt"

    10   if not @ARGV;

    11 

    12 my $pattern = do {

    13     given ($what) {

    14         when ('main')  { qr/^\.option\s(")?(?<item>\S+)(?(1)\1)\smain/ }

    15         when ('vars')  { qr/^\.vitem\s&(?<item>\$\w+)/ }

    16         when ('ops')   { qr/^\.vitem\s&\*(?<item>\$\{\w+:)/ }

    17         when ('conds') { qr/^\.vitem\s&\*(?<item>\w+)\&~\{/ }

    18         when ('funcs') { qr/^\.vitem\s(")?&\*(?<item>\$\{\w+)\{/ }

    19         default        { die "$0: unknown search pattern\n" }

    20     }

    21 };

    22 

    23 say join "\n", sort uniq map { /$pattern/ ? $+{item} : () } <>;