Parsing: partition module into (internal) submodules (#7962)

1 files changed, 96 insertions, 0 deletions

diff --git a/src/Text/Pandoc/Parsing/Math.hs b/src/Text/Pandoc/Parsing/Math.hs
new file mode 100644
index 000000000..f234f9123
--- /dev/null
+++ b/src/Text/Pandoc/Parsing/Math.hs
@@ -0,0 +1,96 @@
+{-# LANGUAGE FlexibleContexts           #-}
+{-# LANGUAGE OverloadedStrings          #-}
+{- |
+Module      : Text.Pandoc.Parsing.Math
+Copyright   : © 2006-2022 John MacFarlane
+License     : GPL-2.0-or-later
+Maintainer  : John MacFarlane <[email protected]>
+
+Parsing of LaTeX math.
+-}
+
+module Text.Pandoc.Parsing.Math
+  ( mathDisplay
+  , mathInline
+  )
+where
+
+import Control.Monad (mzero, when)
+import Data.Text (Text)
+import Text.Parsec ((<|>), Stream(..), notFollowedBy, skipMany, try)
+import Text.Pandoc.Options
+  ( Extension(Ext_tex_math_dollars, Ext_tex_math_single_backslash,
+              Ext_tex_math_double_backslash) )
+import Text.Pandoc.Parsing.Capabilities (HasReaderOptions, guardEnabled)
+import Text.Pandoc.Parsing.Combinators
+import Text.Pandoc.Parsing.Types (ParserT)
+import Text.Pandoc.Shared (trimMath)
+import Text.Pandoc.Sources
+  (UpdateSourcePos, anyChar, char, digit, newline, satisfy, space, string)
+
+import qualified Data.Text as T
+
+mathInlineWith :: (Stream s m Char, UpdateSourcePos s Char)  => Text -> Text -> ParserT s st m Text
+mathInlineWith op cl = try $ do
+  textStr op
+  when (op == "$") $ notFollowedBy space
+  words' <- many1Till (
+                       (T.singleton <$>
+                          satisfy (\c -> not (isSpaceChar c || c == '\\')))
+                   <|> (char '\\' >>
+                           -- This next clause is needed because \text{..} can
+                           -- contain $, \(\), etc.
+                           (try (string "text" >>
+                                 (("\\text" <>) <$> inBalancedBraces 0 ""))
+                            <|>  (\c -> T.pack ['\\',c]) <$> anyChar))
+                   <|> do (blankline <* notFollowedBy' blankline) <|>
+                             (spaceChar <* skipMany spaceChar)
+                          notFollowedBy (char '$')
+                          return " "
+                    ) (try $ textStr cl)
+  notFollowedBy digit  -- to prevent capture of $5
+  return $ trimMath $ T.concat words'
+ where
+  inBalancedBraces :: (Stream s m Char, UpdateSourcePos s Char) => Int -> Text -> ParserT s st m Text
+  inBalancedBraces n = fmap T.pack . inBalancedBraces' n . T.unpack
+
+  inBalancedBraces' :: (Stream s m Char, UpdateSourcePos s Char) => Int -> String -> ParserT s st m String
+  inBalancedBraces' 0 "" = do
+    c <- anyChar
+    if c == '{'
+       then inBalancedBraces' 1 "{"
+       else mzero
+  inBalancedBraces' 0 s = return $ reverse s
+  inBalancedBraces' numOpen ('\\':xs) = do
+    c <- anyChar
+    inBalancedBraces' numOpen (c:'\\':xs)
+  inBalancedBraces' numOpen xs = do
+    c <- anyChar
+    case c of
+         '}' -> inBalancedBraces' (numOpen - 1) (c:xs)
+         '{' -> inBalancedBraces' (numOpen + 1) (c:xs)
+         _   -> inBalancedBraces' numOpen (c:xs)
+
+mathDisplayWith :: (Stream s m Char, UpdateSourcePos s Char) => Text -> Text -> ParserT s st m Text
+mathDisplayWith op cl = try $ fmap T.pack $ do
+  textStr op
+  many1Till (satisfy (/= '\n') <|> (newline <* notFollowedBy' blankline))
+            (try $ textStr cl)
+
+mathDisplay :: (HasReaderOptions st, Stream s m Char, UpdateSourcePos s Char)
+            => ParserT s st m Text
+mathDisplay =
+      (guardEnabled Ext_tex_math_dollars >> mathDisplayWith "$$" "$$")
+  <|> (guardEnabled Ext_tex_math_single_backslash >>
+       mathDisplayWith "\\[" "\\]")
+  <|> (guardEnabled Ext_tex_math_double_backslash >>
+       mathDisplayWith "\\\\[" "\\\\]")
+
+mathInline :: (HasReaderOptions st, Stream s m Char, UpdateSourcePos s Char)
+           => ParserT s st m Text
+mathInline =
+      (guardEnabled Ext_tex_math_dollars >> mathInlineWith "$" "$")
+  <|> (guardEnabled Ext_tex_math_single_backslash >>
+       mathInlineWith "\\(" "\\)")
+  <|> (guardEnabled Ext_tex_math_double_backslash >>
+       mathInlineWith "\\\\(" "\\\\)")