texmath-0.12.8: src/Text/TeXMath/Writers/MathML.hs
{-# LANGUAGE ViewPatterns, ScopedTypeVariables, OverloadedStrings,
TupleSections #-}
{-
Copyright (C) 2009 John MacFarlane <jgm@berkeley.edu>
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 2 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, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
-}
{- | Functions for writing a parsed formula as MathML.
-}
module Text.TeXMath.Writers.MathML (writeMathML)
where
import Text.XML.Light
import Text.TeXMath.Types
import Text.TeXMath.Unicode.ToUnicode
import Data.Generics (everywhere, mkT)
import Text.TeXMath.Shared (getMMLType, handleDownup)
import Text.TeXMath.Readers.MathML.MMLDict (getMathMLOperator)
import qualified Data.Text as T
import Text.Printf
-- | Transforms an expression tree to a MathML XML tree
writeMathML :: DisplayType -> [Exp] -> Element
writeMathML dt exprs =
add_attr dtattr $ math $ showExp Nothing $ EGrouped
$ everywhere (mkT $ handleDownup dt) exprs
where dtattr = Attr (unqual "display") dt'
dt' = case dt of
DisplayBlock -> "block"
DisplayInline -> "inline"
math :: Element -> Element
math = add_attr (Attr (unqual "xmlns") "http://www.w3.org/1998/Math/MathML") . unode "math"
mrow :: [Element] -> Element
mrow = unode "mrow"
showFraction :: Maybe TextType -> FractionType -> Exp -> Exp -> Element
showFraction tt ft x y =
case ft of
NormalFrac -> unode "mfrac" [x', y']
InlineFrac -> withAttribute "displaystyle" "false" .
unode "mfrac" $ [x', y']
DisplayFrac -> withAttribute "displaystyle" "true" .
unode "mfrac" $ [x', y']
NoLineFrac -> withAttribute "linethickness" "0" .
unode "mfrac" $ [x', y']
where x' = showExp tt x
y' = showExp tt y
spaceWidth :: Rational -> Element
spaceWidth w =
withAttribute "width" (dropTrailing0s
(T.pack $ printf "%.3f" (fromRational w :: Double)) <> "em") $ unode "mspace" ()
makeStretchy :: FormType -> Element -> Element
makeStretchy (fromForm -> t) = withAttribute "stretchy" "true"
. withAttribute "form" t
fromForm :: FormType -> T.Text
fromForm FInfix = "infix"
fromForm FPostfix = "postfix"
fromForm FPrefix = "prefix"
makeScaled :: Rational -> Element -> Element
makeScaled x = withAttribute "minsize" s . withAttribute "maxsize" s
where s = dropTrailing0s $ T.pack $ printf "%.3f" (fromRational x :: Double)
dropTrailing0s :: T.Text -> T.Text
dropTrailing0s t = case T.unsnoc t of -- T.spanEnd does not exist
Just (ts, '0') -> addZero $ T.dropWhileEnd (== '0') ts
_ -> t
where
addZero x = case T.unsnoc x of
Just (_, '.') -> T.snoc x '0'
_ -> x
-- Note: Converts strings to unicode directly, as few renderers support those mathvariants.
makeText :: TextType -> T.Text -> Element
makeText a s = case (leadingSp, trailingSp) of
(False, False) -> s'
(True, False) -> mrow [sp, s']
(False, True) -> mrow [s', sp]
(True, True) -> mrow [sp, s', sp]
where sp = spaceWidth (1/3)
s' = withAttribute "mathvariant" attr $ tunode "mtext" $ toUnicode a s
trailingSp = case T.unsnoc s of
Just (_, c) -> T.any (== c) " \t"
_ -> False
leadingSp = case T.uncons s of
Just (c, _) -> T.any (== c) " \t"
_ -> False
attr = getMMLType a
makeArray :: Maybe TextType -> [Alignment] -> [ArrayLine] -> Element
makeArray tt as ls = unode "mtable" $
map (unode "mtr" .
zipWith (\a -> setAlignment a . unode "mtd". map (showExp tt)) as') ls
-- see #205 on the need for style attributes:
where setAlignment AlignLeft =
withAttribute "columnalign" "left" .
withAttribute "style" "text-align: left"
setAlignment AlignRight =
withAttribute "columnalign" "right" .
withAttribute "style" "text-align: right"
setAlignment AlignCenter =
withAttribute "columnalign" "center" .
withAttribute "style" "text-align: center"
as' = as ++ cycle [AlignCenter]
-- Kept as String for Text.XML.Light
withAttribute :: String -> T.Text -> Element -> Element
withAttribute a = add_attr . Attr (unqual a) . T.unpack
accent :: T.Text -> Element
accent = add_attr (Attr (unqual "accent") "true") .
tunode "mo"
makeFence :: FormType -> Element -> Element
makeFence (fromForm -> t) = withAttribute "stretchy" "false" . withAttribute "form" t
showExp' :: Maybe TextType -> Exp -> Element
showExp' tt e =
case e of
ESymbol Accent x -> accent x
ESymbol _ x ->
let isaccent = case (elem "accent") . properties <$>
getMathMLOperator x FPostfix of
Just True -> "true"
_ -> "false"
in withAttribute "accent" isaccent $ tunode "mo" x
_ -> showExp tt e
showExp :: Maybe TextType -> Exp -> Element
showExp tt e =
let toUnicodeMaybe :: TextType -> T.Text -> Maybe T.Text
toUnicodeMaybe textStyle t =
T.pack <$> mapM (toUnicodeChar . (textStyle,)) (T.unpack t)
-- variant node: tries to convert text to appropriate unicode
-- characters depending on style
vnode :: String -> T.Text -> Element
vnode elname t
= case tt of
Nothing -> tunode elname t
Just TextNormal -> withAttribute "mathvariant" "normal" $
tunode elname t
Just textStyle ->
case toUnicodeMaybe textStyle t of
-- if we can't find unicode equivalents, rely on mathvariant:
Nothing -> withAttribute "mathvariant" (getMMLType textStyle) $
tunode elname t
Just t' -> tunode elname t'
in case e of
ENumber x -> vnode "mn" x
EGrouped [x] -> showExp tt x
EGrouped xs -> mrow $ map (showExp tt) xs
EDelimited start end xs -> mrow $
[ makeStretchy FPrefix (vnode "mo" start) | not (T.null start) ] ++
map (either (makeStretchy FInfix . vnode "mo") (showExp tt)) xs ++
[ makeStretchy FPostfix (vnode "mo" end)
| not (T.null end) ]
EIdentifier x -> vnode "mi" x
EMathOperator x -> vnode "mo" x
ESymbol Open x -> makeFence FPrefix $ vnode "mo" x
ESymbol Close x -> makeFence FPostfix $ vnode "mo" x
ESymbol Ord x -> vnode "mi" x
ESymbol _ x -> vnode "mo" x
ESpace x -> spaceWidth x
EFraction ft x y -> showFraction tt ft x y
ESub x y -> unode "msub" $ map (showExp tt) [x, y]
ESuper x y -> unode "msup" $ map (showExp tt) [x, y]
ESubsup x y z -> unode "msubsup" $ map (showExp tt) [x, y, z]
EUnder _ x y -> unode "munder" [showExp tt x, showExp' tt y]
EOver _ x (ESymbol Accent "\8407") -- see #218, gives better rendering for vectors
-> unode "mover" [showExp tt x, showExp' tt (ESymbol Accent "\8594")]
EOver _ x y -> unode "mover" [showExp tt x, showExp' tt y]
EUnderover _ x y z -> unode "munderover"
[showExp tt x, showExp' tt y, showExp' tt z]
EPhantom x -> unode "mphantom" $ showExp tt x
EBoxed x -> withAttribute "notation" "box" .
unode "menclose" $ showExp tt x
ESqrt x -> unode "msqrt" $ showExp tt x
ERoot i x -> unode "mroot" [showExp tt x, showExp tt i]
EScaled s x -> makeScaled s $ showExp tt x
EArray as ls -> makeArray tt as ls
EText a s -> case (tt, a) of
(Just ty, TextNormal) -> makeText ty s
_ -> makeText a s
EStyled a es -> showExp (Just a) (EGrouped es)
-- see https://developer.mozilla.org/en-US/docs/Web/MathML/Element/mstyle
-- Historically, this element accepted almost all the MathML attributes and
-- it was used to override the default attribute values of its descendants.
-- It was later restricted to only a few relevant styling attributes that
-- were used in existing web pages. Nowadays, these styling attributes are
-- common to all MathML elements and so <mstyle> is really just equivalent
-- to an <mrow> element. However, <mstyle> may still be relevant for
-- compatibility with MathML implementations outside browsers.
-- Kept as String for Text.XML.Light
tunode :: String -> T.Text -> Element
tunode s = unode s . T.unpack