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|
{-
Copyright (C) 2017 defanor <defanor@uberspace.net>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
-}
{- |
Module : Pancake.Rendering
Maintainer : defanor <defanor@uberspace.net>
Stability : unstable
Portability : portable
Document rendering: conversion from 'Pandoc' to 'RendererOutput'.
-}
{-# LANGUAGE OverloadedStrings #-}
module Pancake.Rendering ( Denotation(..)
, Styled(..)
, StyledLine
, RendererOutput(..)
, rLinks
, rLines
, rIdentifiers
, rBlocks
, rNotes
, renderDoc
) where
import qualified Text.Pandoc as P
import Network.URI
import Data.List
import System.Console.Terminfo.Color
import Data.String
import Control.Monad.Writer
import Control.Monad.State
import System.FilePath
import Data.Char
import Numeric
import Pancake.Configuration
-- | The type of a list item that should be rendered next.
data Listing = Bulleted
| Ordered Int
deriving (Show, Eq)
-- | Denotations: information that can be ignored, but can also be
-- used to improve the UI.
data Denotation = Link URI
| Image URI
| Math String
| Heading Int
deriving (Show, Eq)
-- | A styled string.
data Styled = Plain String
| Underline Styled
| Bold Styled
| Emph Styled
| Strikethrough Styled
| Subscript Styled
| Superscript Styled
| Fg Color Styled
| Denote Denotation Styled
deriving (Show, Eq)
-- | Just for convenience.
instance IsString Styled where
fromString = Plain
-- | A line of styled elements.
type StyledLine = [Styled]
-- | Renderer state.
data RS = RS { indentationLevel :: Int
, linkCount :: Int
, noteCount :: Int
, lineNumber :: Int
, listing :: Maybe Listing
, columns :: Int
, noWrap :: Bool
, rsConf :: Config
} deriving (Show, Eq)
-- | This is what gets rendered.
data RendererOutput = RLink URI
-- ^ An URI reference.
| RNote [RendererOutput]
-- ^ A note.
| RLine StyledLine
-- ^ A line to render.
| RIdentifier String Int
-- ^ An identifier.
| RBlock Int Int
-- ^ A fixed block's position (start line and end
-- line). These blocks reflect semantics and don't
-- vary as the terminal width changes, so they are
-- safe to rely on for position retention.
deriving (Show, Eq)
-- | Show a reference.
showRef :: String -> Int -> String
showRef digits n = showIntAtBase (length digits) (digits !!) n ""
-- | Extracts links.
rLinks :: [RendererOutput] -> [URI]
rLinks [] = []
rLinks (RLink l:xs) = l : rLinks xs
rLinks (_:xs) = rLinks xs
-- | Extracts text lines.
rLines :: [RendererOutput] -> [StyledLine]
rLines [] = []
rLines (RLine l:xs) = l : rLines xs
rLines (_:xs) = rLines xs
-- | Extracts identifiers.
rIdentifiers :: [RendererOutput] -> [(String, Int)]
rIdentifiers [] = []
rIdentifiers (RIdentifier s i:xs) = (s, i) : rIdentifiers xs
rIdentifiers (_:xs) = rIdentifiers xs
-- | Extracts fixed block positions.
rBlocks :: [RendererOutput] -> [(Int, Int)]
rBlocks [] = []
rBlocks (RBlock s e:xs) = (s, e) : rBlocks xs
rBlocks (_:xs) = rBlocks xs
-- | Extracts notes.
rNotes :: [RendererOutput] -> [[RendererOutput]]
rNotes [] = []
rNotes (RNote l:xs) = l : rNotes xs
rNotes (_:xs) = rNotes xs
-- | Used to render 'Pandoc' docs by writing text lines and collected
-- links using 'Writer'.
type Renderer a = WriterT [RendererOutput] (State RS) a
-- | Runs a 'Renderer'.
runRenderer :: Int
-- ^ Column count (line width).
-> Bool
-- ^ Leave line wrapping to UI.
-> Int
-- ^ Link number to start with.
-> Int
-- ^ Note number to start with.
-> Int
-- ^ Line number to start with.
-> Config
-- ^ Configuration.
-> Renderer a
-- ^ A renderer.
-> [RendererOutput]
-- ^ Collected links and text lines.
runRenderer cols llw ls ns ln cnf r =
let o = snd $ evalState (runWriterT r)
RS { indentationLevel = 0
, linkCount = ls
, noteCount = ns
, lineNumber = ln
, listing = Nothing
, columns = cols
, noWrap = llw
, rsConf = cnf
}
in o ++ concatMap (map RLine . rLines) (rNotes o)
-- | Stores a link, increasing the counter.
storeLink :: URI -> Renderer Int
storeLink u = do
tell [RLink u]
st <- get
put (st { linkCount = linkCount st + 1 })
pure $ linkCount st
-- | Stores a note, increasing the counter.
storeNote :: [RendererOutput] -> Renderer Int
storeNote ro = do
st <- get
put $ st { noteCount = noteCount st + 1 }
mapM_ storeLink $ rLinks ro
let cnt = noteCount st
mark = Superscript . Fg Red . fromString $ "note " ++ show cnt
ro' = case ro of
(RLine l:rest) -> RLine (mark:l):rest
_ -> RLine [mark] : ro
tell [RNote ro']
pure cnt
-- | Stores text lines.
storeLines :: [StyledLine] -> Renderer ()
storeLines l = do
modify (\s -> s { lineNumber = lineNumber s + length l })
tell $ map RLine l
-- | Stores attributes (identifier and line number).
storeAttr :: P.Attr -> Renderer ()
storeAttr ("", _, _) = pure ()
storeAttr (i, _, _) = do
l <- get
tell [RIdentifier i (lineNumber l)]
-- | Increases indentation level, runs a renderer, decreases
-- indentation level.
withIndent :: Renderer a -> Renderer a
withIndent x = do
modify (\s -> s { indentationLevel = indentationLevel s + 1 })
r <- x
modify (\s -> s { indentationLevel = indentationLevel s - 1 })
pure r
-- | Reads indentation level, runs a renderer, restores the original
-- indentation level.
keepIndent :: Renderer a -> Renderer a
keepIndent r = do
st <- get
ret <- r
modify $ \s -> s { indentationLevel = indentationLevel st }
pure ret
-- | Renders indented (with the current indent level) lines.
indented :: [StyledLine] -> Renderer ()
indented slines = do
st <- get
-- The following blocks of the same list item should not be marked.
modify $ \s -> s { listing = Nothing }
let il = indentationLevel st
prefix = case listing st of
Nothing -> ""
(Just Bulleted) -> Fg Yellow "* "
(Just (Ordered n)) -> Fg Yellow $ fromString $ show n ++ ". "
prefixLen = length $ unstyled [prefix]
indent = il + prefixLen
fittedLines = if noWrap st
then slines
else fitLines (columns st - indent) slines
pad = (fromString (replicate indent ' ') :)
padFirst x = fromString (replicate il ' ') : prefix : x
-- The following blocks of the same list item should be indented
-- with the same level. This should be reset to the original value
-- where the listing type is getting set.
modify $ \s -> s { indentationLevel = indent }
case fittedLines of
[] -> pure ()
(l:ls) -> storeLines $ padFirst l : map pad ls
-- This may be unreliable, especially for resulting length estimation,
-- but usually works. Maybe improve someday.
-- | Returns a string as it would be shown on a dumb terminal.
unstyled :: StyledLine -> String
unstyled = concatMap unstyled'
where
unstyled' (Plain s) = s
unstyled' (Underline s) = unstyled' s
unstyled' (Bold s) = unstyled' s
unstyled' (Emph s) = unstyled' s
unstyled' (Strikethrough s) = unstyled' s
unstyled' (Subscript s) = unstyled' s
unstyled' (Superscript s) = unstyled' s
unstyled' (Fg _ s) = unstyled' s
unstyled' (Denote _ s) = unstyled' s
-- | Fits words into terminal lines of a given width.
fitLines :: Int
-- ^ Line width.
-> [[Styled]]
-- ^ Strings: usually words and similar short elements.
-> [StyledLine]
-- ^ Fitted lines.
fitLines 0 _ = []
fitLines maxLen inlineBits = concatMap (map reverse . fitWords') inlineBits
where
splitStyled :: Styled -> [Styled]
splitStyled (Plain s)
| length s > maxLen =
case reverse (takeWhile (<= maxLen) (findIndices isSpace s)) of
(n:_) -> let (t, _:d) = splitAt n s
in Plain t : splitStyled (Plain d)
[] -> let (t, d) = splitAt maxLen s
in Plain t : splitStyled (Plain d)
| otherwise = [Plain s]
splitStyled (Underline s) = map Underline $ splitStyled s
splitStyled (Bold s) = map Bold $ splitStyled s
splitStyled (Emph s) = map Emph $ splitStyled s
splitStyled (Strikethrough s) = map Strikethrough $ splitStyled s
splitStyled (Subscript s) = map Subscript $ splitStyled s
splitStyled (Superscript s) = map Superscript $ splitStyled s
splitStyled (Fg c s) = map (Fg c) $ splitStyled s
splitStyled (Denote d s) = map (Denote d) $ splitStyled s
fitWords' :: [Styled] -> [StyledLine]
fitWords' ws
-- handle empty lines
| null (unstyled ws) = [[]]
| otherwise = fitWords [] 0 ws
fitWords :: [Styled] -> Int -> [Styled] -> [StyledLine]
fitWords curLine curLen (w:ws)
-- handle newline characters
| unstyled [w] == "\n" = curLine : fitWords [] 0 ws
-- a new line
| curLen == 0 = if length (unstyled [w]) <= maxLen
then fitWords [w] (length $ unstyled [w]) ws
else map pure (splitStyled w) ++ fitWords [] 0 ws
-- add a word to a line
| otherwise = let wLen = length (unstyled [w])
spaceAhead = case ws of
(" " : _) -> True
_ -> False
in if curLen + wLen <= maxLen
then fitWords (w:curLine) (curLen + wLen) $
-- if there's an unnecessary space ahead, skip it
if curLen + wLen + 1 > maxLen && spaceAhead
then tail ws
else ws
else curLine : fitWords [] 0 (w:ws)
-- end, no words pending
fitWords _ 0 [] = []
-- end, with words pending
fitWords curLine _ [] = [curLine]
-- | A helper function to put inline elements between two strings
-- (such as parens or quotes).
wrappedInlines :: Styled
-- ^ String on the left.
-> Styled
-- ^ String on the right.
-> [P.Inline]
-- ^ Inlines to wrap.
-> Renderer [Styled]
-- ^ Resulting inlines.
wrappedInlines s e r = do
r' <- concat <$> mapM readInline r
pure $ s : r' ++ [e]
-- | Reads an inline element, producing styled strings. Doesn't render
-- them (i.e., using 'Writer') on its own, but collects links.
readInline :: P.Inline -> Renderer [Styled]
readInline (P.Str s)
| all isSpace s = pure []
| otherwise = pure [fromString s]
readInline (P.Emph s) = concatMap (map Emph) <$> mapM readInline s
readInline (P.Strong s) = concatMap (map Bold) <$> mapM readInline s
readInline (P.Strikeout s) = map Strikethrough <$> wrappedInlines "-" "-" s
readInline (P.Superscript s) = map Superscript <$> wrappedInlines "^{" "}" s
readInline (P.Subscript s) = map Subscript <$> wrappedInlines "_{" "}" s
readInline (P.SmallCaps s) = wrappedInlines "\\sc{" "}" s
readInline (P.Quoted P.SingleQuote s) = wrappedInlines "‘" "’" s
readInline (P.Quoted P.DoubleQuote s) = wrappedInlines "“" "”" s
readInline (P.Cite _ s) = concat <$> mapM readInline s
readInline (P.Code attr s) = do
storeAttr attr
pure . map (Fg Green . fromString) $ intersperse "\n" $ lines s
readInline P.Space = pure [" "]
readInline P.SoftBreak = pure [" "]
readInline P.LineBreak = pure ["\n"]
readInline (P.Math _ s) = pure [Denote (Math s) $ fromString s]
readInline (P.RawInline _ s) = pure [fromString s]
readInline (P.Link attr alt (url, title)) = do
storeAttr attr
case parseURIReference url of
Just uri -> do
a <- mapM readInline alt
let t = case (title, concat a) of
("", []) -> [fromString url]
("", alt') -> alt'
(title', []) -> [fromString title']
(_, alt') -> alt'
cnt <- storeLink uri
let color = case uri of
(URI "" Nothing "" "" ('#':_)) -> Magenta
_ -> Cyan
st <- get
pure $ map (Denote (Link uri) . Fg color) t ++
[Fg Blue $ fromString
(concat ["[", showRef (referenceDigits $ rsConf st) cnt, "]"])]
Nothing -> pure [fromString title]
readInline (P.Image attr alt (url, title)) = do
storeAttr attr
case parseURIReference url of
Nothing -> pure [Fg Red "i", fromString title]
Just uri -> do
a <- mapM readInline alt
let t = case (title, concat a) of
("", []) -> [fromString $ takeFileName $ uriPath uri]
("", alt') -> alt'
(title', []) -> [fromString title']
(_, alt') -> alt'
cnt <- storeLink uri
st <- get
pure $ Denote (Image uri) (Fg Red "i") :
map (Denote (Link uri) . Fg Cyan) t ++
[Fg Blue $ fromString
(concat ["[", showRef (referenceDigits $ rsConf st) cnt, "]"])]
readInline (P.Note bs) = do
-- Minor issues are quite likely with this.
st <- get
-- 12 is somewhat arbitrary, but narrowing the rendered notes so
-- that "^{note xxx}" could be added without overflow.
let ro = runRenderer (columns st - 12) (noWrap st) (linkCount st) (noteCount st) 0
(rsConf st) (renderBlocks bs)
cnt <- storeNote ro
pure [Superscript . Fg Red . fromString $ "[" ++ show cnt ++ "]"]
readInline (P.Span attr i) = do
storeAttr attr
concat <$> mapM readInline i
-- | Reads lines of inline elements.
readInlines :: [P.Inline] -> Renderer [StyledLine]
readInlines i = do
inlineBits <- concat <$> mapM readInline i
pure $ styledLines inlineBits
-- | Like 'readLines', but renders the lines at once, one-by-one,
-- making sure that identifier positions are correct.
renderInlines :: [P.Inline] -> Renderer ()
renderInlines i = do
inlineBits <- concat <$> mapM readInline i
mapM_ (\l -> fixed $ indented [l]) $ styledLines inlineBits
-- | Splits a list of styled elements into styled lines, similar to
-- 'lines'.
styledLines :: [Styled] -> [StyledLine]
styledLines = styledLines' []
where
styledLines' cur [] = [cur]
styledLines' cur (x:xs)
| unstyled [x] == "\n" = cur : styledLines' [] xs
| otherwise = styledLines' (cur ++ [x]) xs
-- | Renders a block element.
renderBlock :: P.Block -> Renderer ()
renderBlock (P.Plain i) = renderInlines i
renderBlock (P.Para i) = renderInlines i
renderBlock (P.LineBlock i) = mapM_ renderInlines i
renderBlock (P.CodeBlock attr s) = do
storeAttr attr
mapM_ (fixed . indented . pure . pure . Fg Green . fromString)
(lines s)
renderBlock (P.RawBlock _ s) =
indented $ map (pure . fromString) $ lines s
renderBlock (P.BlockQuote bs) = withIndent $ renderBlocks bs
renderBlock (P.OrderedList _ bs) = do
st <- get
zipWithM_ (\b n -> modify (\s -> s { listing = Just (Ordered n)
, noWrap = False })
>> fixed (keepIndent (renderBlocks b)))
bs [1..]
modify $ \s -> s { listing = Nothing, noWrap = noWrap st }
renderBlock (P.BulletList bs) = do
st <- get
mapM_ (\b -> modify (\s -> s { listing = Just Bulleted
, noWrap = False })
>> fixed (keepIndent (renderBlocks b)))
bs
modify $ \s -> s { listing = Nothing, noWrap = noWrap st }
renderBlock (P.DefinitionList dl) =
let renderDefinition (term, definition) = do
indented =<< map (map (Fg Yellow)) <$> readInlines term
withIndent $ mapM_ renderBlocks definition
in mapM_ (fixed . renderDefinition) dl
renderBlock (P.Header level attr i) = do
storeAttr attr
indented =<< map (map (Denote (Heading level) . Bold . Fg Green)
. ([fromString (replicate level '#'), " "] ++))
<$> readInlines i
renderBlock P.HorizontalRule = do
st <- get
indented [[Fg Black $
fromString $ replicate (columns st - indentationLevel st * 2) '-']]
renderBlock (P.Table caption aligns widths headers rows) = do
indented =<< readInlines caption
-- Use pandoc-provided widths if they are set, calculate them
-- otherwise.
let widthsAreSet = case widths of
[] -> False
w -> minimum w /= maximum w
ws <- if widthsAreSet then pure widths else do
lens <- map sum . transpose <$> mapM
(mapM (fmap (length . unstyled . concat . rLines) . renderCell 80)) rows
pure $ map (\l -> if sum lens == 0
then 0
else fromIntegral l / fromIntegral (sum lens) * 0.7
+ 1 / fromIntegral (length lens) * 0.3) lens
let withHead = if all null headers then id else (headers :)
mapM_ (\r -> fixed (renderBlock P.HorizontalRule) >> fixed (tableRow ws r))
(withHead rows)
fixed $ renderBlock P.HorizontalRule
where
renderCell :: Int -> [P.Block] -> Renderer [RendererOutput]
renderCell w blocks = do
st <- get
pure $ runRenderer w False (linkCount st) (noteCount st)
(lineNumber st) (rsConf st) $ renderBlocks blocks
tableCell :: (P.Alignment, Int, [P.Block]) -> Renderer [StyledLine]
tableCell (a, w, blocks) = do
l <- renderCell w blocks
mapM_ storeLink $ rLinks l
modify (\s -> s { noteCount = noteCount s + length (rNotes l) })
tell $ map (uncurry RIdentifier) $ rIdentifiers l
pure $ map (padCell a w) $ rLines l
padCell :: P.Alignment -> Int -> StyledLine -> StyledLine
padCell a w x =
let pLen = w - length (unstyled x)
halfLen :: Rational
halfLen = fromIntegral pLen / 2
(lPad, rPad) = case a of
P.AlignRight -> (pLen, 0)
P.AlignCenter -> ( ceiling halfLen, floor halfLen )
_ -> (0, pLen)
mkPadding l = [fromString (replicate l ' ')]
in concat [mkPadding lPad, x, mkPadding rPad]
tableRow :: [Double] -> [[P.Block]] -> Renderer ()
tableRow ws cols = do
st <- get
let maxWidth = columns st - indentationLevel st - ((length cols - 1) * 3)
widths' = map (\w -> floor (fromIntegral maxWidth * w)) ws
cells <- mapM tableCell $ zip3 aligns widths' cols
let maxLines = foldr (max . length) 0 cells
padded = zipWith (\w c -> c ++ replicate (maxLines - length c)
[fromString $ replicate w ' ']) widths' cells
indented $ map (mconcat . intersperse (pure $ Fg Black " | "))
$ transpose padded
renderBlock (P.Div attr b) = do
storeAttr attr
st <- get
let i = if indentDivs $ rsConf st
then withIndent
else id
i $ renderBlocks b
renderBlock P.Null = pure ()
-- | Checks whether a block is a list (ordered-, bullet-, or
-- definition-).
isList :: P.Block -> Bool
isList P.OrderedList {} = True
isList P.BulletList {} = True
isList P.DefinitionList {} = True
isList _ = False
-- | Determines whether a line should be skipped before a block.
skipBefore :: P.Block -> Bool
skipBefore P.Header {} = True
skipBefore P.Para {} = True
skipBefore (P.Div _ (b:_)) = skipBefore b
skipBefore _ = False
-- | Determines whether a line should be skipped after a block.
skipAfter :: P.Block -> Bool
skipAfter P.Header {} = True
skipAfter P.Para {} = True
skipAfter (P.Div _ bs@(_:_)) = skipAfter $ last bs
skipAfter b = isList b
-- | Stores an element position for fixed elements.
fixed :: Renderer a -> Renderer a
fixed r = do
st <- get
ret <- r
st' <- get
tell [RBlock (lineNumber st) (lineNumber st')]
pure ret
-- | Renders block elements with empty lines between some of them.
renderBlocks :: [P.Block] -> Renderer ()
renderBlocks [] = pure ()
renderBlocks [b] = fixed $ renderBlock b
renderBlocks (b1:bs@(b2:_)) = do
fixed $ renderBlock b1
when (skipAfter b1 || skipBefore b2) $
fixed $ storeLines [[]]
renderBlocks bs
-- | Renders a document.
renderDoc :: Int
-- ^ Number of columns.
-> Bool
-- ^ Leave line wrapping to UI.
-> Config
-- ^ Configuration.
-> P.Pandoc
-- ^ Document to render.
-> [RendererOutput]
-- ^ Rendered document.
renderDoc cols llw cnf (P.Pandoc _ blocks) =
runRenderer cols llw 0 0 1 cnf $ renderBlocks blocks
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