Copyright	Copyright (C) 2013-2019 John MacFarlane
License	BSD3
Maintainer	John MacFarlane <jgm@berkeley.edu>
Stability	alpha
Portability	portable
Safe Haskell	None
Language	Haskell98

Text.Pandoc.Walk

Description

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 -> [String]
extractURL (Link _ _ (u,_)) = [u]
extractURL (Image _ _ (u,_)) = [u]
extractURL _ = []

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

Synopsis

class Walkable a b where
- walk :: (a -> a) -> b -> b
- walkM :: (Monad m, Applicative m, Functor m) => (a -> m a) -> b -> m b
- query :: Monoid c => (a -> c) -> b -> c
queryBlock :: (Walkable a Citation, Walkable a [Block], Walkable a [Inline], Monoid c) => (a -> c) -> Block -> c
queryCitation :: (Walkable a [Inline], Monoid c) => (a -> c) -> Citation -> c
queryInline :: (Walkable a Citation, Walkable a [Block], Walkable a [Inline], Monoid c) => (a -> c) -> Inline -> c
queryMetaValue :: (Walkable a MetaValue, Walkable a [Block], Walkable a [Inline], Monoid c) => (a -> c) -> MetaValue -> c
queryPandoc :: (Walkable a Meta, Walkable a [Block], Monoid c) => (a -> c) -> Pandoc -> c
walkBlockM :: (Walkable a [Block], Walkable a [Inline], Monad m, Applicative m, Functor m) => (a -> m a) -> Block -> m Block
walkCitationM :: (Walkable a [Inline], Monad m, Applicative m, Functor m) => (a -> m a) -> Citation -> m Citation
walkInlineM :: (Walkable a Citation, Walkable a [Block], Walkable a [Inline], Monad m, Applicative m, Functor m) => (a -> m a) -> Inline -> m Inline
walkMetaValueM :: (Walkable a MetaValue, Walkable a [Block], Walkable a [Inline], Monad f, Applicative f, Functor f) => (a -> f a) -> MetaValue -> f MetaValue
walkPandocM :: (Walkable a Meta, Walkable a [Block], Monad m, Applicative m, Functor m) => (a -> m a) -> Pandoc -> m Pandoc

Documentation

class Walkable a b where #

Minimal complete definition

walkM, query

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.

Instances

Instances details

Walkable Inline Citation #
Instance details Defined in Text.Pandoc.Walk Methods walk :: (Inline -> Inline) -> Citation -> Citation # walkM :: (Monad m, Applicative m, Functor m) => (Inline -> m Inline) -> Citation -> m Citation # query :: Monoid c => (Inline -> c) -> Citation -> c #
Walkable Inline Inline #
Instance details Defined in Text.Pandoc.Walk Methods walk :: (Inline -> Inline) -> Inline -> Inline # walkM :: (Monad m, Applicative m, Functor m) => (Inline -> m Inline) -> Inline -> m Inline # query :: Monoid c => (Inline -> c) -> Inline -> c #
Walkable Inline Block #
Instance details Defined in Text.Pandoc.Walk Methods walk :: (Inline -> Inline) -> Block -> Block # walkM :: (Monad m, Applicative m, Functor m) => (Inline -> m Inline) -> Block -> m Block # query :: Monoid c => (Inline -> c) -> Block -> c #
Walkable Inline MetaValue #
Instance details Defined in Text.Pandoc.Walk Methods walk :: (Inline -> Inline) -> MetaValue -> MetaValue # walkM :: (Monad m, Applicative m, Functor m) => (Inline -> m Inline) -> MetaValue -> m MetaValue # query :: Monoid c => (Inline -> c) -> MetaValue -> c #
Walkable Inline Meta #
Instance details Defined in Text.Pandoc.Walk Methods walk :: (Inline -> Inline) -> Meta -> Meta # walkM :: (Monad m, Applicative m, Functor m) => (Inline -> m Inline) -> Meta -> m Meta # query :: Monoid c => (Inline -> c) -> Meta -> c #
Walkable Inline Pandoc #
Instance details Defined in Text.Pandoc.Walk Methods walk :: (Inline -> Inline) -> Pandoc -> Pandoc # walkM :: (Monad m, Applicative m, Functor m) => (Inline -> m Inline) -> Pandoc -> m Pandoc # query :: Monoid c => (Inline -> c) -> Pandoc -> c #
Walkable Block Citation #
Instance details Defined in Text.Pandoc.Walk Methods walk :: (Block -> Block) -> Citation -> Citation # walkM :: (Monad m, Applicative m, Functor m) => (Block -> m Block) -> Citation -> m Citation # query :: Monoid c => (Block -> c) -> Citation -> c #
Walkable Block Inline #
Instance details Defined in Text.Pandoc.Walk Methods walk :: (Block -> Block) -> Inline -> Inline # walkM :: (Monad m, Applicative m, Functor m) => (Block -> m Block) -> Inline -> m Inline # query :: Monoid c => (Block -> c) -> Inline -> c #
Walkable Block Block #
Instance details Defined in Text.Pandoc.Walk Methods walk :: (Block -> Block) -> Block -> Block # walkM :: (Monad m, Applicative m, Functor m) => (Block -> m Block) -> Block -> m Block # query :: Monoid c => (Block -> c) -> Block -> c #
Walkable Block MetaValue #
Instance details Defined in Text.Pandoc.Walk Methods walk :: (Block -> Block) -> MetaValue -> MetaValue # walkM :: (Monad m, Applicative m, Functor m) => (Block -> m Block) -> MetaValue -> m MetaValue # query :: Monoid c => (Block -> c) -> MetaValue -> c #
Walkable Block Meta #
Instance details Defined in Text.Pandoc.Walk Methods walk :: (Block -> Block) -> Meta -> Meta # walkM :: (Monad m, Applicative m, Functor m) => (Block -> m Block) -> Meta -> m Meta # query :: Monoid c => (Block -> c) -> Meta -> c #
Walkable Block Pandoc #
Instance details Defined in Text.Pandoc.Walk Methods walk :: (Block -> Block) -> Pandoc -> Pandoc # walkM :: (Monad m, Applicative m, Functor m) => (Block -> m Block) -> Pandoc -> m Pandoc # query :: Monoid c => (Block -> c) -> Pandoc -> c #
Walkable Meta Meta #
Instance details Defined in Text.Pandoc.Walk Methods walk :: (Meta -> Meta) -> Meta -> Meta # walkM :: (Monad m, Applicative m, Functor m) => (Meta -> m Meta) -> Meta -> m Meta # query :: Monoid c => (Meta -> c) -> Meta -> c #
Walkable Pandoc Pandoc #
Instance details Defined in Text.Pandoc.Walk Methods walk :: (Pandoc -> Pandoc) -> Pandoc -> Pandoc # walkM :: (Monad m, Applicative m, Functor m) => (Pandoc -> m Pandoc) -> Pandoc -> m Pandoc # query :: Monoid c => (Pandoc -> c) -> Pandoc -> c #
(Foldable t, Traversable t, Walkable a b) => Walkable a (t b) #
Instance details Defined in Text.Pandoc.Walk Methods walk :: (a -> a) -> t b -> t b # walkM :: (Monad m, Applicative m, Functor m) => (a -> m a) -> t b -> m (t b) # query :: Monoid c => (a -> c) -> t b -> c #
(Walkable a b, Walkable a c) => Walkable a (b, c) #
Instance details Defined in Text.Pandoc.Walk Methods walk :: (a -> a) -> (b, c) -> (b, c) # walkM :: (Monad m, Applicative m, Functor m) => (a -> m a) -> (b, c) -> m (b, c) # query :: Monoid c0 => (a -> c0) -> (b, c) -> c0 #
Walkable [Inline] Citation #
Instance details Defined in Text.Pandoc.Walk Methods walk :: ([Inline] -> [Inline]) -> Citation -> Citation # walkM :: (Monad m, Applicative m, Functor m) => ([Inline] -> m [Inline]) -> Citation -> m Citation # query :: Monoid c => ([Inline] -> c) -> Citation -> c #
Walkable [Inline] Inline #
Instance details Defined in Text.Pandoc.Walk Methods walk :: ([Inline] -> [Inline]) -> Inline -> Inline # walkM :: (Monad m, Applicative m, Functor m) => ([Inline] -> m [Inline]) -> Inline -> m Inline # query :: Monoid c => ([Inline] -> c) -> Inline -> c #
Walkable [Inline] Block #
Instance details Defined in Text.Pandoc.Walk Methods walk :: ([Inline] -> [Inline]) -> Block -> Block # walkM :: (Monad m, Applicative m, Functor m) => ([Inline] -> m [Inline]) -> Block -> m Block # query :: Monoid c => ([Inline] -> c) -> Block -> c #
Walkable [Inline] MetaValue #
Instance details Defined in Text.Pandoc.Walk Methods walk :: ([Inline] -> [Inline]) -> MetaValue -> MetaValue # walkM :: (Monad m, Applicative m, Functor m) => ([Inline] -> m [Inline]) -> MetaValue -> m MetaValue # query :: Monoid c => ([Inline] -> c) -> MetaValue -> c #
Walkable [Inline] Meta #
Instance details Defined in Text.Pandoc.Walk Methods walk :: ([Inline] -> [Inline]) -> Meta -> Meta # walkM :: (Monad m, Applicative m, Functor m) => ([Inline] -> m [Inline]) -> Meta -> m Meta # query :: Monoid c => ([Inline] -> c) -> Meta -> c #
Walkable [Inline] Pandoc #
Instance details Defined in Text.Pandoc.Walk Methods walk :: ([Inline] -> [Inline]) -> Pandoc -> Pandoc # walkM :: (Monad m, Applicative m, Functor m) => ([Inline] -> m [Inline]) -> Pandoc -> m Pandoc # query :: Monoid c => ([Inline] -> c) -> Pandoc -> c #
Walkable [Block] Citation #
Instance details Defined in Text.Pandoc.Walk Methods walk :: ([Block] -> [Block]) -> Citation -> Citation # walkM :: (Monad m, Applicative m, Functor m) => ([Block] -> m [Block]) -> Citation -> m Citation # query :: Monoid c => ([Block] -> c) -> Citation -> c #
Walkable [Block] Inline #
Instance details Defined in Text.Pandoc.Walk Methods walk :: ([Block] -> [Block]) -> Inline -> Inline # walkM :: (Monad m, Applicative m, Functor m) => ([Block] -> m [Block]) -> Inline -> m Inline # query :: Monoid c => ([Block] -> c) -> Inline -> c #
Walkable [Block] Block #
Instance details Defined in Text.Pandoc.Walk Methods walk :: ([Block] -> [Block]) -> Block -> Block # walkM :: (Monad m, Applicative m, Functor m) => ([Block] -> m [Block]) -> Block -> m Block # query :: Monoid c => ([Block] -> c) -> Block -> c #
Walkable [Block] MetaValue #
Instance details Defined in Text.Pandoc.Walk Methods walk :: ([Block] -> [Block]) -> MetaValue -> MetaValue # walkM :: (Monad m, Applicative m, Functor m) => ([Block] -> m [Block]) -> MetaValue -> m MetaValue # query :: Monoid c => ([Block] -> c) -> MetaValue -> c #
Walkable [Block] Meta #
Instance details Defined in Text.Pandoc.Walk Methods walk :: ([Block] -> [Block]) -> Meta -> Meta # walkM :: (Monad m, Applicative m, Functor m) => ([Block] -> m [Block]) -> Meta -> m Meta # query :: Monoid c => ([Block] -> c) -> Meta -> c #
Walkable [Block] Pandoc #
Instance details Defined in Text.Pandoc.Walk Methods walk :: ([Block] -> [Block]) -> Pandoc -> Pandoc # walkM :: (Monad m, Applicative m, Functor m) => ([Block] -> m [Block]) -> Pandoc -> m Pandoc # query :: Monoid c => ([Block] -> c) -> Pandoc -> c #
Walkable [Inline] [Inline] #
Instance details Defined in Text.Pandoc.Walk Methods walk :: ([Inline] -> [Inline]) -> [Inline] -> [Inline] # walkM :: (Monad m, Applicative m, Functor m) => ([Inline] -> m [Inline]) -> [Inline] -> m [Inline] # query :: Monoid c => ([Inline] -> c) -> [Inline] -> c #
Walkable [Block] [Block] #
Instance details Defined in Text.Pandoc.Walk Methods walk :: ([Block] -> [Block]) -> [Block] -> [Block] # walkM :: (Monad m, Applicative m, Functor m) => ([Block] -> m [Block]) -> [Block] -> m [Block] # query :: Monoid c => ([Block] -> c) -> [Block] -> c #

queryBlock :: (Walkable a Citation, Walkable a [Block], 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.

queryCitation :: (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.

queryInline :: (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.

queryMetaValue :: (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.

queryPandoc :: (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.

walkBlockM :: (Walkable a [Block], Walkable a [Inline], 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.

walkCitationM :: (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.

walkInlineM :: (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.

walkMetaValueM :: (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.

walkPandocM :: (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.