Copyright	Copyright (C) 2013 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

Documentation

class Walkable a b where Source #

Minimal complete definition

walk, walkM, query

Methods

walk :: (a -> a) -> b -> b Source #

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, Functor m) => (a -> m a) -> b -> m b Source #

A monadic version of walk.

query :: Monoid c => (a -> c) -> b -> c Source #

query f x walks the structure x (bottom up) and applies f to every a, appending the results.

Instances

Walkable Inline Citation Source #
Methods walk :: (Inline -> Inline) -> Citation -> Citation Source # walkM :: (Monad m, Functor m) => (Inline -> m Inline) -> Citation -> m Citation Source # query :: Monoid c => (Inline -> c) -> Citation -> c Source #
Walkable Inline Inline Source #
Methods walk :: (Inline -> Inline) -> Inline -> Inline Source # walkM :: (Monad m, Functor m) => (Inline -> m Inline) -> Inline -> m Inline Source # query :: Monoid c => (Inline -> c) -> Inline -> c Source #
Walkable Inline Block Source #
Methods walk :: (Inline -> Inline) -> Block -> Block Source # walkM :: (Monad m, Functor m) => (Inline -> m Inline) -> Block -> m Block Source # query :: Monoid c => (Inline -> c) -> Block -> c Source #
Walkable Inline MetaValue Source #
Methods walk :: (Inline -> Inline) -> MetaValue -> MetaValue Source # walkM :: (Monad m, Functor m) => (Inline -> m Inline) -> MetaValue -> m MetaValue Source # query :: Monoid c => (Inline -> c) -> MetaValue -> c Source #
Walkable Inline Meta Source #
Methods walk :: (Inline -> Inline) -> Meta -> Meta Source # walkM :: (Monad m, Functor m) => (Inline -> m Inline) -> Meta -> m Meta Source # query :: Monoid c => (Inline -> c) -> Meta -> c Source #
Walkable Inline Pandoc Source #
Methods walk :: (Inline -> Inline) -> Pandoc -> Pandoc Source # walkM :: (Monad m, Functor m) => (Inline -> m Inline) -> Pandoc -> m Pandoc Source # query :: Monoid c => (Inline -> c) -> Pandoc -> c Source #
Walkable Block Citation Source #
Methods walk :: (Block -> Block) -> Citation -> Citation Source # walkM :: (Monad m, Functor m) => (Block -> m Block) -> Citation -> m Citation Source # query :: Monoid c => (Block -> c) -> Citation -> c Source #
Walkable Block Inline Source #
Methods walk :: (Block -> Block) -> Inline -> Inline Source # walkM :: (Monad m, Functor m) => (Block -> m Block) -> Inline -> m Inline Source # query :: Monoid c => (Block -> c) -> Inline -> c Source #
Walkable Block Block Source #
Methods walk :: (Block -> Block) -> Block -> Block Source # walkM :: (Monad m, Functor m) => (Block -> m Block) -> Block -> m Block Source # query :: Monoid c => (Block -> c) -> Block -> c Source #
Walkable Block MetaValue Source #
Methods walk :: (Block -> Block) -> MetaValue -> MetaValue Source # walkM :: (Monad m, Functor m) => (Block -> m Block) -> MetaValue -> m MetaValue Source # query :: Monoid c => (Block -> c) -> MetaValue -> c Source #
Walkable Block Meta Source #
Methods walk :: (Block -> Block) -> Meta -> Meta Source # walkM :: (Monad m, Functor m) => (Block -> m Block) -> Meta -> m Meta Source # query :: Monoid c => (Block -> c) -> Meta -> c Source #
Walkable Block Pandoc Source #
Methods walk :: (Block -> Block) -> Pandoc -> Pandoc Source # walkM :: (Monad m, Functor m) => (Block -> m Block) -> Pandoc -> m Pandoc Source # query :: Monoid c => (Block -> c) -> Pandoc -> c Source #
Walkable Meta Meta Source #
Methods walk :: (Meta -> Meta) -> Meta -> Meta Source # walkM :: (Monad m, Functor m) => (Meta -> m Meta) -> Meta -> m Meta Source # query :: Monoid c => (Meta -> c) -> Meta -> c Source #
Walkable Pandoc Pandoc Source #
Methods walk :: (Pandoc -> Pandoc) -> Pandoc -> Pandoc Source # walkM :: (Monad m, Functor m) => (Pandoc -> m Pandoc) -> Pandoc -> m Pandoc Source # query :: Monoid c => (Pandoc -> c) -> Pandoc -> c Source #
(Foldable t, Traversable t, Walkable a b) => Walkable a (t b) Source #
Methods walk :: (a -> a) -> t b -> t b Source # walkM :: (Monad m, Functor m) => (a -> m a) -> t b -> m (t b) Source # query :: Monoid c => (a -> c) -> t b -> c Source #
(Walkable a b, Walkable a c) => Walkable a (b, c) Source #
Methods walk :: (a -> a) -> (b, c) -> (b, c) Source # walkM :: (Monad m, Functor m) => (a -> m a) -> (b, c) -> m (b, c) Source # query :: Monoid c => (a -> c) -> (b, c) -> c Source #