NAME

App::podsel - Select Pod::Elemental nodes using CSel syntax

VERSION

This document describes version 0.008 of App::podsel (from Perl distribution App-podsel), released on 2020-04-29.

SYNOPSIS

FUNCTIONS

podsel

Usage:

 podsel(%args) -> [status, msg, payload, meta]

Select Pod::Elemental nodes using CSel syntax.

This function is not exported.

Arguments ('*' denotes required arguments):

  • expr => str

  • file => filename (default: "-")

  • node_actions => array[str] (default: ["print_as_string"])

    Specify action(s) to perform on matching nodes.

    Each action can be one of the following:

    • count will print the number of matching nodes.

    • print_method will call on or more of the node object's methods and print the result. Example:

      print_method:as_string

    • dump will show a indented text representation of the node and its descendants. Each line will print information about a single node: its class, followed by the value of one or more attributes. You can specify which attributes to use in a dot-separated syntax, e.g.:

      dump:tag.id.class

      which will result in a node printed like this:

      HTML::Element tag=p id=undef class=undef

    By default, if no attributes are specified, id is used. If the node class does not support the attribute, or if the value of the attribute is undef, then undef is shown.

    • eval will execute Perl code for each matching node. The Perl code will be called with arguments: ($node). For convenience, $_ is also locally set to the matching node. Example in htmlsel you can add this action:

      eval:'print $_->tag'

      which will print the tag name for each matching HTML::Element node.

  • node_actions_on_descendants => str (default: "")

    Specify how descendants should be actioned upon.

    This option sets how node action is performed (See node_actions option).

    When set to '' (the default), then only matching nodes are actioned upon.

    When set to 'descendants_depth_first', then after each matching node is actioned upon by an action, the descendants of the matching node are also actioned, in depth-first order. This option is sometimes necessary e.g. when your node's as_string() method shows a node's string representation that does not include its descendants.

  • select_action => str (default: "csel")

    Specify how we should select nodes.

    The default is csel, which will select nodes from the tree using the CSel expression. Note that the root node itself is not included. For more details on CSel expression, refer to Data::CSel.

    root will return a single node which is the root node.

  • transforms => array[str]

    Apply one or more Pod::Elemental::Transform's.

    TRANSFORMS

    First of all, by default, the "stock" Pod::Elemental parser will be generic and often not very helpful in parsing your typical POD (Perl 5 variant) documents. You often want to add:

     -t Pod5 -t Nester

    or -5 for short, which is equivalent to the above. Except in some simple cases. See examples below.

    The following are available transforms:

    • Pod5

    Equivalent to this:

     Pod::Elemental::Transformer::Pod5->new->transform_node($tree);
    • Nester

    Equivalent to this:

     my $nester;
     
     $nester = Pod::Elemental::Transformer::Nester->new({
         top_selector      => Pod::Elemental::Selectors::s_command('head3'),
         content_selectors => [
             Pod::Elemental::Selectors::s_command([ qw(head4) ]),
             Pod::Elemental::Selectors::s_flat(),
         ],
     });
     $nester->new->transform_node($tree);
     
     $nester = Pod::Elemental::Transformer::Nester->new({
         top_selector      => Pod::Elemental::Selectors::s_command('head2'),
         content_selectors => [
             Pod::Elemental::Selectors::s_command([ qw(head3 head4) ]),
             Pod::Elemental::Selectors::s_flat(),
         ],
     });
     $nester->new->transform_node($tree);
     
     $nester = Pod::Elemental::Transformer::Nester->new({
         top_selector      => Pod::Elemental::Selectors::s_command('head1'),
         content_selectors => [
             Pod::Elemental::Selectors::s_command([ qw(head2 head3 head4) ]),
             Pod::Elemental::Selectors::s_flat(),
         ],
     });
     $nester->new->transform_node($tree);

    EXAMPLES

    Note: pmpath is a CLI utility that returns the path of a locally installed Perl module. It's distributed in App::PMUtils distribution.

    Select all head1 commands (only print the command lines and not the content):

     % podsel C<pmpath strict> 'Command[command=head1]'
     =head1 NAME
     
     =head1 SYNOPSIS
     
     =head1 DESCRIPTION
     
     =head1 HISTORY

    Select all head1 commands that contain "SYN" in them (only print the command lines and not the content):

     % podsel C<pmpath strict> 'Command[command=head1][content =~ /synopsis/i]'
     =head1 SYNOPSIS

    Select all head1 commands that contain "SYN" in them (but now also print the content; note now the use of the Nested class selector and the -5 flag to create a nested document tree instead of a flat one):

     % podsel -5 C<pmpath strict> 'Nested[command=head1][content =~ /synopsis/i]'
     =head1 SYNOPSIS
     
         use strict;
     
         use strict "vars";
         use strict "refs";
         use strict "subs";
     
         use strict;
         no strict "vars";

    List of head commands in POD of List::Util:

     % podsel C<pmpath List::Util> 'Command[command =~ /head/]'
     =head1 NAME
     
     =head1 SYNOPSIS
     
     =head1 DESCRIPTION
     
     =head1 LIST-REDUCTION FUNCTIONS
     
     =head2 reduce
     
     =head2 reductions
     
     ...
     
     =head1 KEY/VALUE PAIR LIST FUNCTIONS
     
     =head2 pairs
     
     =head2 unpairs
     
     =head2 pairkeys
     
     =head2 pairvalues
     
     ...

    List only key/value pair list functions and not list-reduction ones:

     % podsel -5 C<pmpath List::Util> 'Nested[command=head1][content =~ /pair/i] Nested[command=head2]' --print-method content
     pairs
     unpairs
     pairkeys
     pairvalues
     pairgrep
     pairfirst
     pairmap

Returns an enveloped result (an array).

First element (status) is an integer containing HTTP status code (200 means OK, 4xx caller error, 5xx function error). Second element (msg) is a string containing error message, or 'OK' if status is 200. Third element (payload) is optional, the actual result. Fourth element (meta) is called result metadata and is optional, a hash that contains extra information.

Return value: (any)

HOMEPAGE

Please visit the project's homepage at https://metacpan.org/release/App-podsel.

SOURCE

Source repository is at https://github.com/perlancar/perl-App-podsel.

BUGS

Please report any bugs or feature requests on the bugtracker website https://rt.cpan.org/Public/Dist/Display.html?Name=App-podsel

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.

SEE ALSO

AUTHOR

perlancar <perlancar@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2020, 2019 by perlancar@cpan.org.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.