Modulepandoc-types-1.23.1Haskell2010

Text.Pandoc.Walk

Functions for manipulating Pandoc documents or extracting information from them by walking the Pandoc structure (or intermediate structures like '[Block]' or '[Inline]'. These are faster (by a factor of four or five) than the generic functions defined in Text.Pandoc.Generic.

Here's a simple example, defining a function that replaces all the level 3+ headers in a document with regular paragraphs in ALL CAPS:

import Text.Pandoc.Definition
import Text.Pandoc.Walk
import Data.Char (toUpper)

modHeader :: Block -> Block
modHeader (Header n _ xs) | n >= 3 = Para $ walk allCaps xs
modHeader x = x

allCaps :: Inline -> Inline
allCaps (Str xs) = Str $ map toUpper xs
allCaps x = x

changeHeaders :: Pandoc -> Pandoc
changeHeaders = walk modHeader

query can be used, for example, to compile a list of URLs linked to in a document:

extractURL :: Inline -> [Text]
extractURL (Link _ _ (u,_)) = [u]
extractURL (Image _ _ (u,_)) = [u]
extractURL _ = []

extractURLs :: Pandoc -> [Text]
extractURLs = query extractURL

1 class
24 values

Packagepandoc-types-1.23.1
Exports25
LanguageHaskell2010
LicenceBSD-3-Clause
SourceWalk.hs

classclass Walkable a b where

Methods

walk :: (a -> a) -> b -> b
walk f x walks the structure x (bottom up) and replaces every occurrence of an a with the result of applying f to it.
walkM :: (Monad m, Applicative m, Functor m) => (a -> m a) -> b -> m b
A monadic version of walk.
query :: Monoid c => (a -> c) -> b -> c
query f x walks the structure x (bottom up) and applies f to every a, appending the results.

Instances58Walkable, …

Walkable Block BlockDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Block CaptionDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Block CellDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Block CitationDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Block InlineDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Block MetaDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Block MetaValueDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Block PandocDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Block RowDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Block TableBodyDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Block TableFootDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Block TableHeadDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Inline BlockDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Inline CaptionDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Inline CellDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Inline CitationDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Inline InlineDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Inline MetaDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Inline MetaValueDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Inline PandocDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Inline RowDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Inline TableBodyDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Inline TableFootDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Inline TableHeadDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Meta MetaDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Meta PandocDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable MetaValue MetaDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable MetaValue MetaValueDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable MetaValue PandocDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable Pandoc PandocDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
(Foldable t, Traversable t, Walkable a b) => Walkable a (t b)Defined in pandoc-types-1.23.1 · Text.Pandoc.Walk
(Walkable a b, Walkable a c) => Walkable a (b, c)Defined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Block] BlockDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Block] CaptionDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Block] CellDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Block] CitationDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Block] InlineDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Block] MetaDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Block] MetaValueDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Block] PandocDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Block] RowDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Block] TableBodyDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Block] TableFootDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Block] TableHeadDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Inline] BlockDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Inline] CaptionDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Inline] CellDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Inline] CitationDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Inline] InlineDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Inline] MetaDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Inline] MetaValueDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Inline] PandocDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Inline] RowDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Inline] TableBodyDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Inline] TableFootDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Inline] TableHeadDefined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Block] [Block]Defined in pandoc-types-1.23.1 · Text.Pandoc.Walk
Walkable [Inline] [Inline]Defined in pandoc-types-1.23.1 · Text.Pandoc.Walk

valuequeryBlock

:: (Walkable a Citation, Walkable a [Block], Walkable a Row, Walkable a Caption, Walkable a TableHead, Walkable a TableBody, Walkable a TableFoot, Walkable a [Inline], Monoid c)
=> a -> c
-> Block
-> c

Perform a query on elements nested below a Block element by querying all directly nested lists of Inlines or Blocks.

valuequeryCaption

:: (Walkable a [Block], Walkable a [Inline], Walkable a ShortCaption, Monoid c)
=> a -> c
-> Caption
-> c

Query the elements below a Cell element.

valuequeryRow :: (Walkable a Cell, Monoid c) => (a -> c) -> Row -> c

Query the elements below a Row element.

valuequeryTableHead :: (Walkable a Row, Monoid c) => (a -> c) -> TableHead -> c

Query the elements below a TableHead element.

valuequeryTableBody :: (Walkable a Row, Monoid c) => (a -> c) -> TableBody -> c

Query the elements below a TableBody element.

valuequeryTableFoot :: (Walkable a Row, Monoid c) => (a -> c) -> TableFoot -> c

Query the elements below a TableFoot element.

valuequeryCell :: (Walkable a [Block], Monoid c) => (a -> c) -> Cell -> c

Query the elements below a Cell element.

valuequeryCitation

:: (Walkable a [Inline], Monoid c)
=> a -> c
-> Citation
-> c

Perform a query on elements nested below a Citation element by querying the prefix and postfix Inline lists.

valuequeryInline

:: (Walkable a Citation, Walkable a [Block], Walkable a [Inline], Monoid c)
=> a -> c
-> Inline
-> c

Perform a query on elements nested below an Inline element by querying nested lists of Inlines, Blocks, or Citations.

valuequeryMetaValue

:: (Walkable a MetaValue, Walkable a [Block], Walkable a [Inline], Monoid c)
=> a -> c
-> MetaValue
-> c

Perform a query on elements nested below a MetaValue element by querying all directly nested lists of Inlines, list of Blocks, or lists or maps of MetaValues.

valuequeryMetaValue' :: Monoid c => (MetaValue -> c) -> MetaValue -> c

Perform a query on MetaValue elements nested below a MetaValue element

valuequeryPandoc

:: (Walkable a Meta, Walkable a [Block], Monoid c)
=> a -> c
-> Pandoc
-> c

Query a pandoc element by recursing first into its Meta data and then append the result of recursing into the list of Blocks.

valuewalkBlockM

:: (Walkable a [Block], Walkable a [Inline], Walkable a Row, Walkable a Caption, Walkable a TableHead, Walkable a TableBody, Walkable a TableFoot, Monad m, Applicative m, Functor m)
=> a -> m a
-> Block
-> m Block

Helper method to walk to elements nested below Block nodes.

When walking a block with this function, only the contents of the traversed block element may change. The element itself, i.e. its constructor, its Attr, and its raw text value, will remain unchanged.

valuewalkCaptionM

:: (Walkable a [Block], Walkable a [Inline], Monad m, Walkable a ShortCaption)
=> a -> m a
-> Caption
-> m Caption

Helper method to walk the elements nested below Caption nodes.

valuewalkRowM :: (Walkable a Cell, Monad m) => (a -> m a) -> Row -> m Row

Helper method to walk the elements nested below Row nodes. The Attr component is not changed by this operation.

valuewalkTableHeadM

:: (Walkable a Row, Monad m)
=> a -> m a
-> TableHead
-> m TableHead

Helper method to walk the elements nested below TableHead nodes. The Attr component is not changed by this operation.

valuewalkTableBodyM

:: (Walkable a Row, Monad m)
=> a -> m a
-> TableBody
-> m TableBody

Helper method to walk the elements nested below TableBody nodes. The Attr and RowHeadColumns components are not changed by this operation.

valuewalkTableFootM

:: (Walkable a Row, Monad m)
=> a -> m a
-> TableFoot
-> m TableFoot

Helper method to walk the elements nested below TableFoot nodes. The Attr component is not changed by this operation.

valuewalkCellM :: (Walkable a [Block], Monad m) => (a -> m a) -> Cell -> m Cell

Helper method to walk the elements nested below Cell nodes. Only the [Block] cell content is changed by this operation.

valuewalkCitationM

:: (Walkable a [Inline], Monad m, Applicative m, Functor m)
=> a -> m a
-> Citation
-> m Citation

Helper method to walk to elements nested below Citation nodes.

The non-inline contents of a citation will remain unchanged during traversal. Only the inline contents, viz. the citation's prefix and postfix, will be traversed further and can thus be changed during this operation.

valuewalkInlineM

:: (Walkable a Citation, Walkable a [Block], Walkable a [Inline], Monad m, Applicative m, Functor m)
=> a -> m a
-> Inline
-> m Inline

Helper method to walk to elements nested below Inline nodes.

When walking an inline with this function, only the contents of the traversed inline element may change. The element itself, i.e. its constructor, cannot be changed.

valuewalkMetaValueM

:: (Walkable a MetaValue, Walkable a [Block], Walkable a [Inline], Monad f, Applicative f, Functor f)
=> a -> f a
-> MetaValue
-> f MetaValue

Helper method to walk to elements nested below MetaValue nodes.

When walking a meta value with this function, only the contents of the traversed meta value element may change. MetaBool and MetaString will always remain unchanged.

valuewalkMetaValueM'

:: (Monad f, Applicative f, Functor f)
=> MetaValue -> f MetaValue
-> MetaValue
-> f MetaValue

Helper method to walk MetaValue nodes nested below MetaValue nodes.

valuewalkPandocM

:: (Walkable a Meta, Walkable a [Block], Monad m, Applicative m, Functor m)
=> a -> m a
-> Pandoc
-> m Pandoc

Helper method to walk the components of a Pandoc element.