| Copyright | Copyright (C) 2013-2019 John MacFarlane | 
|---|---|
| License | BSD3 | 
| Maintainer | John MacFarlane <jgm@berkeley.edu> | 
| Stability | alpha | 
| Portability | portable | 
| Safe Haskell | None | 
| Language | Haskell2010 | 
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 -> [Text] extractURL (Link _ _ (u,_)) = [u] extractURL (Image _ _ (u,_)) = [u] extractURL _ = [] extractURLs :: Pandoc -> [Text] extractURLs = query extractURL
Synopsis
- class Walkable a b where
- queryBlock :: (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
- queryCaption :: (Walkable a [Block], Walkable a [Inline], Walkable a ShortCaption, Monoid c) => (a -> c) -> Caption -> c
- queryRow :: (Walkable a Cell, Monoid c) => (a -> c) -> Row -> c
- queryTableHead :: (Walkable a Row, Monoid c) => (a -> c) -> TableHead -> c
- queryTableBody :: (Walkable a Row, Monoid c) => (a -> c) -> TableBody -> c
- queryTableFoot :: (Walkable a Row, Monoid c) => (a -> c) -> TableFoot -> c
- queryCell :: (Walkable a [Block], Monoid c) => (a -> c) -> Cell -> 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], 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
- walkCaptionM :: (Walkable a [Block], Walkable a [Inline], Monad m, Walkable a ShortCaption) => (a -> m a) -> Caption -> m Caption
- walkRowM :: (Walkable a Cell, Monad m) => (a -> m a) -> Row -> m Row
- walkTableHeadM :: (Walkable a Row, Monad m) => (a -> m a) -> TableHead -> m TableHead
- walkTableBodyM :: (Walkable a Row, Monad m) => (a -> m a) -> TableBody -> m TableBody
- walkTableFootM :: (Walkable a Row, Monad m) => (a -> m a) -> TableFoot -> m TableFoot
- walkCellM :: (Walkable a [Block], Monad m) => (a -> m a) -> Cell -> m Cell
- 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 Source #
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, Applicative 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
queryBlock :: (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 Source #
Perform a query on elements nested below a BlockInlines or Blocks.
queryCaption :: (Walkable a [Block], Walkable a [Inline], Walkable a ShortCaption, Monoid c) => (a -> c) -> Caption -> c Source #
Query the elements below a Cell element.
queryRow :: (Walkable a Cell, Monoid c) => (a -> c) -> Row -> c Source #
Query the elements below a Row element.
queryTableHead :: (Walkable a Row, Monoid c) => (a -> c) -> TableHead -> c Source #
Query the elements below a TableHead element.
queryTableBody :: (Walkable a Row, Monoid c) => (a -> c) -> TableBody -> c Source #
Query the elements below a TableBody element.
queryTableFoot :: (Walkable a Row, Monoid c) => (a -> c) -> TableFoot -> c Source #
Query the elements below a TableFoot element.
queryCell :: (Walkable a [Block], Monoid c) => (a -> c) -> Cell -> c Source #
Query the elements below a Cell element.
queryCitation :: (Walkable a [Inline], Monoid c) => (a -> c) -> Citation -> c Source #
Perform a query on elements nested below a CitationInline lists.
queryInline :: (Walkable a Citation, Walkable a [Block], Walkable a [Inline], Monoid c) => (a -> c) -> Inline -> c Source #
Perform a query on elements nested below an InlineInlines, Blocks, or Citations.
queryMetaValue :: (Walkable a MetaValue, Walkable a [Block], Walkable a [Inline], Monoid c) => (a -> c) -> MetaValue -> c Source #
Perform a query on elements nested below a MetaValueInlines, list of Blocks, or
 lists or maps of MetaValues.
walkBlockM :: (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 Source #
walkCaptionM :: (Walkable a [Block], Walkable a [Inline], Monad m, Walkable a ShortCaption) => (a -> m a) -> Caption -> m Caption Source #
Helper method to walk the elements nested below Caption
 nodes.
walkTableBodyM :: (Walkable a Row, Monad m) => (a -> m a) -> TableBody -> m TableBody Source #
Helper method to walk the elements nested below TableBodyAttrRowHeadColumns
walkCitationM :: (Walkable a [Inline], Monad m, Applicative m, Functor m) => (a -> m a) -> Citation -> m Citation Source #
Helper method to walk to elements nested below Citation
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 Source #
Helper method to walk to elements nested below Inline
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 Source #
Helper method to walk to elements nested below MetaValue
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.