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|
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE StrictData #-}
{- |
Module : Text.Pandoc.Transforms
Copyright : © 2006-2024 John MacFarlane
License : GPL-2.0-or-later
Maintainer : John MacFarlane <jgm@berkeley@edu>
Transformation of a Pandoc document post-parsing
-}
module Text.Pandoc.Transforms
( Transform
, applyTransforms
, adjustLinksAndIds
, eastAsianLineBreakFilter
, filterIpynbOutput
, headerShift
) where
import Data.List (sortOn)
import Data.Text (Text)
import Network.URI (unEscapeString)
import Text.DocLayout (charWidth)
import Text.Pandoc.Definition
( Pandoc (..), Attr, Block (..), Format (..), Inline (..) )
import Text.Pandoc.Generic (bottomUp)
import Text.Pandoc.Options (Extensions)
import Text.Pandoc.Shared (stringify, textToIdentifier)
import Text.Pandoc.Walk (walk)
import qualified Data.Text as T
import qualified Text.Pandoc.Builder as B
-- | Transformation of a Pandoc document post-parsing
type Transform = Pandoc -> Pandoc
-- | Apply a list of transforms to a document, in order.
applyTransforms :: Monad m => [Transform] -> Pandoc -> m Pandoc
applyTransforms transforms d = return $ foldr ($) d transforms
-- | Prefixes identifiers with a string derived from the filepath of
-- @thisfile@; fixes links to targets in @allfiles@ accordingly.
adjustLinksAndIds :: Extensions -- ^ defines how IDs are generated
-> Text -- ^ thisfile
-> [Text] -- ^ allfiles
-> Transform
adjustLinksAndIds exts thisfile allfiles
| length allfiles > 1 = walk fixInline . walk fixBlock
| otherwise = id
where
-- fix ids in blocks
fixBlock :: Block -> Block
fixBlock (CodeBlock attr t) = CodeBlock (fixAttrs attr) t
fixBlock (Header lev attr ils) = Header lev (fixAttrs attr) ils
fixBlock (Table attr cap cols th tbs tf) =
Table (fixAttrs attr) cap cols th tbs tf
fixBlock (Div attr bs) = Div (fixAttrs attr) bs
fixBlock x = x
-- fix ids and links in inlines
fixInline :: Inline -> Inline
fixInline (Code attr t) = Code (fixAttrs attr) t
fixInline (Link attr ils (url,tit)) =
Link (fixAttrs attr) ils (fixURL url,tit)
fixInline (Image attr ils (url,tit)) =
Image (fixAttrs attr) ils (fixURL url,tit)
fixInline (Span attr ils) = Span (fixAttrs attr) ils
fixInline x = x
-- add thisfile as prefix of identifier
fixAttrs :: Attr -> Attr
fixAttrs (i,cs,kvs)
| T.null i = (i,cs,kvs)
| otherwise =
(T.intercalate "__"
(filter (not . T.null) [toIdent thisfile, i]),
cs, kvs)
-- turns a filepath into an identifier
toIdent :: Text -> Text
toIdent = textToIdentifier exts . T.intercalate "__" .
T.split (\c -> c == '/' || c == '\\')
-- if URL begins with file from allfiles, convert to
-- an internal link with the appropriate identifier
fixURL :: Text -> Text
fixURL u =
let (a,b) = T.break (== '#') $ T.pack . unEscapeString . T.unpack $ u
filepart = if T.null a
then toIdent thisfile
else toIdent a
fragpart = T.dropWhile (== '#') b
in if T.null a || a `elem` allfiles
then "#" <> T.intercalate "__"
(filter (not . T.null) [filepart, fragpart])
else u
-- | Process ipynb output cells. If mode is Nothing,
-- remove all output. If mode is Just format, select
-- best output for the format. If format is not ipynb,
-- strip out ANSI escape sequences from CodeBlocks (see #5633).
filterIpynbOutput :: Maybe Format -> Pandoc -> Pandoc
filterIpynbOutput mode = walk go
where go (Div (ident, "output":os, kvs) bs) =
case mode of
Nothing -> Div (ident, "output":os, kvs) []
-- "best" for ipynb includes all formats:
Just fmt
| fmt == Format "ipynb"
-> Div (ident, "output":os, kvs) bs
| otherwise -> Div (ident, "output":os, kvs) $
walk removeANSI $
take 1 $ sortOn rank bs
where
rank (RawBlock (Format "html") _)
| fmt == Format "html" = 1 :: Int
| fmt == Format "markdown" = 3
| otherwise = 4
rank (RawBlock (Format "latex") _)
| fmt == Format "latex" = 1
| fmt == Format "markdown" = 3
| otherwise = 4
rank (RawBlock f _)
| fmt == f = 1
| otherwise = 4
rank (Para [Image{}]) = 2
rank _ = 3
removeANSI (CodeBlock attr code) =
CodeBlock attr (removeANSIEscapes code)
removeANSI x = x
removeANSIEscapes t
| Just cs <- T.stripPrefix "\x1b[" t =
removeANSIEscapes $ T.drop 1 $ T.dropWhile (/='m') cs
| Just (c, cs) <- T.uncons t = T.cons c $ removeANSIEscapes cs
| otherwise = ""
go x = x
-- | Remove soft breaks between East Asian characters.
eastAsianLineBreakFilter :: Pandoc -> Pandoc
eastAsianLineBreakFilter = bottomUp go
where go (x:SoftBreak:y:zs)
| Just (_, b) <- T.unsnoc $ stringify x
, Just (c, _) <- T.uncons $ stringify y
, charWidth b == 2
, charWidth c == 2
= x:y:zs
| otherwise
= x:SoftBreak:y:zs
go xs
= xs
-- | Shift header levels up or down.
headerShift :: Int -> Pandoc -> Pandoc
headerShift n (Pandoc meta (Header m _ ils : bs))
| n < 0
, m + n == 0 = headerShift n $
B.setTitle (B.fromList ils) $ Pandoc meta bs
headerShift n (Pandoc meta bs) = Pandoc meta (walk shift bs)
where
shift :: Block -> Block
shift (Header level attr inner)
| level + n > 0 = Header (level + n) attr inner
| otherwise = Para inner
shift x = x
|
