Document elements are encoded as Perl data structures equivalent to the JSON structure, emitted with
pandoc output format "json". This JSON structure is subject to minor changes between versions of pandoc.
All elements are blessed objects that provide common element methods (all elements), attribute methods
(elements with attributes), and additional element-specific methods.
COMMONMETHODSto_json
Return the element as JSON encoded string. The following are equivalent:
$element->to_json;
JSON->new->utf8->canonical->convert_blessed->encode($element);
The serialization format can be adjusted to different pandoc versions with module and environment
variable "PANDOC_VERSION" or with Document element properties "api_version" and "pandoc_version".
When writing filters you can normally just rely on the api version value obtained from pandoc, since
pandoc expects to receive the same JSON format as it emits.
name
Return the name of the element, e.g. "Para" for a paragraph element.
content
Return the element content. For most elements (Para, Emph, Str...) the content is an array reference with
child elements. Other elements consist of multiple parts; for instance the Link element has attributes
("attr", "id", "class", "classes", "keyvals") a link text ("content") and a link target ("target") with
"url" and "title".
is_block
True if the element is a Block element
is_inline
True if the element is an inline Inline element
is_meta
True if the element is a Metadata element
is_document
True if the element is a Document element
as_block
Return the element unmodified if it is a block element or wrapped in a Plain or Div otherwise.
match($selector)
Check whether the element matches a given Pandoc::Selector (given as instance or string).
walk(...)
Walk the element tree with Pandoc::Walker
query(...)
Query the element to extract results with Pandoc::Walker
transform(...)
Transform the element tree with Pandoc::Walker
string
Returns a concatenated string of element content, leaving out all formatting.
ATTRIBUTEMETHODS
Some elements have attributes which can be an identifier, ordered class names and ordered key-value
pairs. Elements with attributes provide the following methods:
attr
Get or set the attributes in Pandoc internal structure:
[ $id, [ @classes ], [ [ key => $value ], ... ] ]
See helper function attributes to create this structure.
keyvals
Get all attributes (id, class, and key-value pairs) as new Hash::MultiValue instance, or replace all key-
value pairs plus id and/or class if these are included as field names. All class fields are split by
whitespaces.
$e->keyvals # return new Hash::MultiValue
$e->keyvals( $HashMultiValue ) # update by instance of Hash::MultiValue
$e->keyvals( key => $value, ... ) # update by list of key-value pairs
$e->keyvals( \%hash ) # update by hash reference
$e->keyvals( { } ) # remove all key-value pairs
$e->keyvals( id => '', class => '' ) # remove all key-value pairs, id, class
id
Get or set the identifier. See also Pandoc::Filter::HeaderIdentifiers for utility functions to handle
Header identifiers.
class
Get or set the list of classes, separated by whitespace.
add_attribute($name=>$value)
Append an attribute. The special attribute names "id" and "class" set or append identifier or class,
respectively.
DOCUMENTELEMENTDocument
Root element, consisting of metadata hash ("meta"), document element array ("content"="blocks") and
optional "api_version". The constructor accepts either two arguments and an optional named parameter
"api_version":
Document { %meta }, [ @blocks ], api_version => $version_string
or a hash with three fields for metadata, document content, and an optional pandoc API version:
{
meta => { %metadata },
blocks => [ @content ],
pandoc-api-version => [ $major, $minor, $revision ]
}
The latter form is used as pandoc JSON format since pandoc release 1.18. If no api version is given, it
will be set to 1.21 which was also introduced with pandoc release 2.10.
A third ("old") form is accepted for compatibility with pandoc JSON format before release 1.18 and since
release 1.12.1: an array with two elements for metadata and document content respectively.
[ { unMeta => { %meta } }, [ @blocks ] ]
The api version is set to 1.16 in this case, but older versions down to 1.12.3 used the same format.
Document elements provide the following special methods in addition to common element methods:
api_version([$api_version])
Return the pandoc-types version (aka "pandoc-api-version") of this document as Pandoc::Version object
or sets it to a new value. This version determines how method to_json serializes the document.
See "PANDOC VERSIONS" for details.
pandoc_version([$pandoc_version])
Return the minimum required version of pandoc executable compatible with the api_version of this
document. The following are equivalent:
$doc->pandoc_version;
pandoc_version( $doc );
If used as setter, sets the api version of this document to be compatible with the given pandoc
version.
content or blocks
Get or set the array of block elements of the document.
meta([$metadata])
Get and/or set combined document metadata. Use method "value" to get selected metadata fields and
values.
value([$pointer][%options])
Get selected document metadata field value(s). See Pandoc::Metadata for documentation. Can also be
called as "metavalue", so the following are equivalent:
$doc->value( ... );
$doc->meta->value( ... );
$doc->metavalue( ... );
to_pandoc([[$pandoc,]@arguments])
Process the document with Pandoc executable and return its output:
$doc->to_pandoc( -o => 'doc.html' );
my $markdown = $doc->to_pandoc( -t => 'markdown' );
The first argument can optionally be an instance of Pandoc to use a specific executable.
to_...([@arguments])
Process the document into "markdown" (pandoc's extended Markdown), "latex" (LaTeX), "html" (HTML),
"rst" (reStructuredText), or "plain" (plain text). The following are equivalent:
$doc->to_markdown( @args );
$doc->to_pandoc( @args, '-t' => 'markdown' );
outline([$depth])
Returns an outline of the document structure based on Header elements. The outline is a hierarchical
hash reference with the following fields:
header
Header element (not included at the document root)
blocks
List of block elements before the next Header element (of given depth or less if a maximum depth
was given)
sections
List of subsections, each having the same outline structure.
BLOCKELEMENTSBlockQuote
Block quote, consisting of a list of blocks ("content")
BlockQuote [ @blocks ]
BulletList
Unnumbered list of items ("content"="items"), each a list of blocks
BulletList [ [ @blocks ] ]
CodeBlock
Code block (literal string "content") with attributes ("attr", "id", "class", "classes", "keyvals")
CodeBlock $attributes, $content
DefinitionList
Definition list, consisting of a list of pairs ("content"="items"), each a term ("term", a list of
inlines) and one or more definitions ("definitions", a list of blocks).
DefinitionList [ @definitions ]
# each item in @definitions being a pair of the form
[ [ @inlines ], [ @blocks ] ]
Div
Generic container of blocks ("content") with attributes ("attr", "id", "class", "classes", "keyvals").
Div $attributes, [ @blocks ]
Header
Header with "level" (integer), attributes ("attr", "id", "class", "classes", "keyvals"), and text
("content", a list of inlines).
Header $level, $attributes, [ @inlines ]
HorizontalRule
Horizontal rule
HorizontalRule
LineBlock
List of lines ("content"), each a list of inlines.
LineBlock [ @lines ]
This element was added in pandoc 1.18. Before it was represented Para elements with embedded LineBreak
elements. This old serialization form can be enabled by setting $PANDOC_VERSION package variable to a
lower version number.
Null
Nothing
Null
OrderedList
Numbered list of items ("content"="items"), each a list of blocks), preceded by list attributes (start
number, numbering style, and delimiter).
OrderedList [ $start, $style, $delim ], [ [ @blocks ] ]
Supported styles are "DefaultStyle", "Example", "Decimal", "LowerRoman", "UpperRoman", "LowerAlpha", and
"UpperAlpha".
Supported delimiters are "DefaultDelim", "Period", "OneParen", and "TwoParens".
Para
Paragraph, consisting of a list of Inline elements ("content").
Para [ $elements ]
Plain
Plain text, not a paragraph, consisting of a list of Inline elements ("content").
Plain [ @inlines ]
RawBlock
Raw block with "format" and "content" string.
RawBlock $format, $content
Table
Table, with "caption", column "alignments", relative column "widths" (0 = default), column "headers"
(each a list of blocks), and "rows" (each a list of lists of blocks).
Table [ @inlines ], [ @alignments ], [ @width ], [ @headers ], [ @rows ]
Possible alignments are "AlignLeft", "AlignRight", "AlignCenter", and "AlignDefault".
An example:
Table [Str "Example"], [AlignLeft,AlignRight], [0.0,0.0],
[[Plain [Str "name"]]
,[Plain [Str "number"]]],
[[[Plain [Str "Alice"]]
,[Plain [Str "42"]]]
,[[Plain [Str "Bob"]]
,[Plain [Str "23"]]]];
INLINEELEMENTSCite
Citation, a list of "citations" and a list of inlines ("content"). See helper function citation to
construct citations.
Cite [ @citations ], [ @inlines ]
Code
Inline code, a literal string ("content") with attributes ("attr", "id", "class", "classes", "keyvals")
Code attributes { %attr }, $content
Emph
Emphasized text, a list of inlines ("content").
Emph [ @inlines ]
Image
Image with alt text ("content", a list of inlines) and "target" (list of "url" and "title") with
attributes ("attr", "id", "class", "classes", "keyvals").
Image attributes { %attr }, [ @inlines ], [ $url, $title ]
Serializing the attributes is disabled in api version less then 1.16.
LineBreak
Hard line break
LineBreak
Link
Hyperlink with link text ("content", a list of inlines) and "target" (list of "url" and "title") with
attributes ("attr", "id", "class", "classes", "keyvals").
Link attributes { %attr }, [ @inlines ], [ $url, $title ]
Serializing the attributes is disabled in api version less then 1.16.
Math
TeX math, given as literal string ("content") with "type" (one of "DisplayMath" and "InlineMath").
Math $type, $content
Note
Footnote or Endnote, a list of blocks ("content").
Note [ @blocks ]
Quoted
Quoted text with quote "type" (one of "SingleQuote" and "DoubleQuote") and a list of inlines ("content").
Quoted $type, [ @inlines ]
RawInline
Raw inline with "format" (a string) and "content" (a string).
RawInline $format, $content
SmallCaps
Small caps text, a list of inlines ("content").
SmallCaps [ @inlines ]
SoftBreak
Soft line break
SoftBreak
This element was added in pandoc 1.16 as a matter of editing convenience to preserve line breaks (as
opposed to paragraph breaks) from input source to output. If you are going to feed a document containing
"SoftBreak" elements to Pandoc < 1.16 you will have to set the package variable or environment variable
"PANDOC_VERSION" to 1.15 or below.
Space
Inter-word space
Space
Span
Generic container of inlines ("content") with attributes ("attr", "id", "class", "classes", "keyvals").
Span attributes { %attr }, [ @inlines ]
Str
Plain text, a string ("content").
Str $content
Strikeout
Strikeout text, a list of inlines ("content").
Strikeout [ @inlines ]
Strong
Strongly emphasized text, a list of inlines ("content").
Strong [ @inlines ]
Subscript
Subscripted text, a list of inlines ("content").
Supscript [ @inlines ]
Superscript
Superscripted text, a list of inlines ("content").
Superscript [ @inlines ]
Underline
Underlined text, a list of inlines ("content").
Underline [ @inlines ]
This element was added in pandoc 2.10. If you are going to feed a document containing "Underline"
elements to Pandoc < 2.10 you will have to set the package variable or environment variable
"PANDOC_VERSION" to 2.9 or below.
Table
Underlined text, a list of inlines ("content").
Underline [ @inlines ]
This element was added in pandoc 2.10. If you are going to feed a document containing "Underline"
elements to Pandoc < 2.10 you will have to set the package variable or environment variable
"PANDOC_VERSION" to 2.9 or below.
METADATAELEMENTS
See Pandoc::Metadata for documentation of metadata elements "MetaBool", "MetaString", "MetaMap",
"MetaInlines", "MetaList", and "MetaBlocks".
Helper function "metadata" can be used to convert scalars, hash references, array references, and Pandoc
Inline/Block elements into metadata elements.
TYPEKEYWORDS
The following document elements are only as used as type keywords in other document elements:
• "SingleQuote", "DoubleQuote"
• "DisplayMath", "InlineMath"
• "AuthorInText", "SuppressAuthor", "NormalCitation"
• "AlignLeft", "AlignRight", "AlignCenter", "AlignDefault"
• "DefaultStyle", "Example", "Decimal", "LowerRoman", "UpperRoman", "LowerAlpha", "UpperAlpha"
• "DefaultDelim", "Period", "OneParen", "TwoParens"
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