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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" Pandoc::Filter \- process Pandoc abstract syntax tree .SH "SYNOPSIS" .IX Header "SYNOPSIS" Filter \f(CW\*(C`flatten.pl\*(C'\fR, adopted from pandoc scripting documentation , converts level 2+ headers to regular paragraphs: .PP .Vb 2 \& use Pandoc::Filter; \& use Pandoc::Elements; \& \& pandoc_filter Header => sub { \& return unless $_\->level >= 2; # keep \& return Para [ Emph $_\->content ]; # replace \& }; .Ve .PP Apply this filter on a Markdown file like this: .PP .Vb 1 \& pandoc \-\-filter flatten.pl \-t markdown < input.md .Ve .PP See for more examples of filters. .SH "DESCRIPTION" .IX Header "DESCRIPTION" Pandoc::Filter provides tools to modify the abstract syntax tree (\s-1AST\s0) of Pandoc documents. See Pandoc::Elements for \s-1AST\s0 elements that can be modified by filters. .PP The function interface (see \*(L"\s-1FUNCTIONS\*(R"\s0) directly reads \s-1AST\s0 and format from \&\s-1STDIN\s0 and \s-1ARGV\s0 and prints the transformed \s-1AST\s0 to \s-1STDOUT. \s0 .PP The object oriented interface (see \*(L"\s-1METHODS\*(R"\s0) requires to: .PP .Vb 2 \& my $filter = Pandoc::Filter\->new( ... ); # create a filter object \& $filter\->apply( $ast, $format ); # pass it an AST for processing .Ve .PP If you don't need the \f(CW\*(C`format\*(C'\fR parameter, consider using the interface provided by module Pandoc::Walker instead. It can be used both: .PP .Vb 2 \& transform $ast, ...; # as function \& $ast\->transform( ... ); # or as method .Ve .SH "ACTIONS" .IX Header "ACTIONS" An action is a code reference that is executed on matching document elements of an \s-1AST.\s0 The action is passed a reference to the current element, the output format (the empty string by default), and the document metadata (an empty hash by default). The current element is also given in the special variable \f(CW$_\fR for convenience. .PP The action is expected to return an element, an empty array reference, or \&\f(CW\*(C`undef\*(C'\fR to modify, remove, or keep a traversed element in the \s-1AST. \s0 .SH "METHODS" .IX Header "METHODS" .ie n .SS "new( @actions | %actions )" .el .SS "new( \f(CW@actions\fP | \f(CW%actions\fP )" .IX Subsection "new( @actions | %actions )" Create a new filter object with one or more actions (see \*(L"\s-1ACTIONS\*(R"\s0). If actions are given as hash, key values are used to check which elements to apply for, e.g. .PP .Vb 4 \& Pandoc::Filter\->new( \& Header => sub { ... }, \& \*(AqSuscript|Superscript\*(Aq => sub { ... } \& ) .Ve .ie n .SS "apply( $ast [, $format [, $metadata ] ] )" .el .SS "apply( \f(CW$ast\fP [, \f(CW$format\fP [, \f(CW$metadata\fP ] ] )" .IX Subsection "apply( $ast [, $format [, $metadata ] ] )" Apply all actions to a given abstract syntax tree (\s-1AST\s0). The \s-1AST\s0 is modified in place and also returned for convenience. Additional argument format and metadata are also passed to the action function. Metadata is taken from the Document by default (if the \s-1AST\s0 is a Document root). .SS "action" .IX Subsection "action" Return a code reference to call all actions. .SH "FUNCTIONS" .IX Header "FUNCTIONS" The following functions are exported by default. .ie n .SS "pandoc_filter( @actions | %actions )" .el .SS "pandoc_filter( \f(CW@actions\fP | \f(CW%actions\fP )" .IX Subsection "pandoc_filter( @actions | %actions )" Read a single line of \s-1JSON\s0 from \s-1STDIN,\s0 apply actions on the document content and print the resulting \s-1AST\s0 as single line of \s-1JSON. \s0Pandoc::Filter::Usage is used to print filter documentation if called with command line argument \&\f(CW\*(C`\-\-help\*(C'\fR, \f(CW\*(C`\-h\*(C'\fR, or \f(CW\*(C`\-?\*(C'\fR. .SH "FILTER MODULES" .IX Header "FILTER MODULES" .IP "Pandoc::Filter::HeaderIdentifiers" 4 .IX Item "Pandoc::Filter::HeaderIdentifiers" .PD 0 .IP "Pandoc::Filter::Multifilter" 4 .IX Item "Pandoc::Filter::Multifilter" .IP "Pandoc::Filter::ImagesFromCode" 4 .IX Item "Pandoc::Filter::ImagesFromCode" .PD .SH "SEE ALSO" .IX Header "SEE ALSO" This module is a port of pandocfilters from Python to modern Perl. .SH "COPYRIGHT AND LICENSE" .IX Header "COPYRIGHT AND LICENSE" Copyright 2014\- Jakob Vo\*8 .PP \&\s-1GNU\s0 General Public License, Version 2 .PP This module is heavily based on Pandoc by John MacFarlane.