Added maths bracketing

src/Lexer.hs

@@ -29,15 +29,16 @@ data Token
   | BirdTrack
   | BoldOpen
   | BoldClose
-  | BracketOpen
-  | BracketClose
   | EmphasisOpen
   | EmphasisClose
   | MonospaceOpen
   | MonospaceClose
   | Newline
-  | ParenOpen
+  | Escape
-  | ParenClose
+  | MathsParenOpen
+  | MathsParenClose
+  | MathsBracketOpen
+  | MathsBracketClose
   | QuoteOpen
   | QuoteClose
   | Space
@@ -57,7 +58,10 @@ lexText = go
         toks <-
           choice $
             Parsec.try
-              <$> [ newlineToken
+              <$> [ mathsBracket
+                  , mathsParens
+                  , escape -- maths go before escape to avoid mismatch
+                  , newlineToken
                   , spaceToken
                   , quotes
                   , textElement
@@ -85,8 +89,6 @@ textElement =
       <$> [ emphasis
           , bold
           , monospace
-          , parens
-          , brackets
           , angles
           ]
 
@@ -110,8 +112,20 @@ delimited a b c d = delimitedMaybe a b c (Just d)
 delimitedSymmetric :: Parser a -> Token -> Token -> Parser [LocatedToken]
 delimitedSymmetric s t1 t2 = delimited s s t1 t2
 
+eol :: Parser ()
+eol = void "\n" <|> Parsec.eof
+
+mathsBracket :: Lexer
+mathsBracket = delimited (void $ "\\[") (void "\\]") MathsBracketOpen MathsBracketClose
+
+mathsParens :: Lexer
+mathsParens = delimited (void $ "\\(") (void "\\)") MathsParenOpen MathsParenClose
+
 birdTrack :: Lexer
-birdTrack = delimitedMaybe (void ">> ") (void "\n" <|> Parsec.eof) BirdTrack Nothing
+birdTrack = delimitedMaybe (void ">> ") eol BirdTrack Nothing
+
+escape :: Lexer
+escape = delimitedMaybe (void "\\") eol Escape Nothing
 
 quotes :: Lexer
 quotes = delimitedSymmetric "\"" QuoteOpen QuoteClose
@@ -125,11 +139,11 @@ bold = delimitedSymmetric "__" BoldOpen BoldClose
 monospace :: Lexer
 monospace = delimitedSymmetric "@" MonospaceOpen MonospaceClose
 
-parens :: Parser [LocatedToken]
+-- parens :: Parser [LocatedToken]
-parens = delimited "(" ")" ParenOpen ParenClose
+-- parens = delimited "(" ")" ParenOpen ParenClose
 
-brackets :: Lexer
+-- brackets :: Lexer
-brackets = delimited "[" "]" ParenOpen ParenClose
+-- brackets = delimited "[" "]" ParenOpen ParenClose
 
 angles :: Parser [LocatedToken]
 angles = delimited "<" ">" AngleOpen AngleClose

test/Spec.hs

@@ -17,6 +17,8 @@ main = hspec $ do
   describe "Lexer" do
     describe "minimal" do
       it "handles unicode" unicode
+      it "escapes" escaping
+      it "maths" maths
       it "space chars" space
       it "bare string" someString
       it "emphasis" emphatic
@@ -35,6 +37,26 @@ main = hspec $ do
 -- Tests
 ------------
 
+maths :: IO ()
+maths = do
+  "\\[some math\\]"
+    `shouldLexTo` [ (1, 1, MathsBracketOpen)
+                  , (1, 2, Token "some math")
+                  , (1, 13, MathsBracketClose)
+                  ]
+  "\\(other maths\\)"
+    `shouldLexTo` [ (1, 1, MathsParenOpen)
+                  , (1, 2, Token "other maths")
+                  , (1, 15, MathsParenClose)
+                  ]
+
+escaping :: Expectation
+escaping =
+  "\\("
+    `shouldLexTo` [ (1, 1, Escape)
+                  , (1, 2, Token "(")
+                  ]
+
 unicode :: Expectation
 unicode =
   "ドラゴンクエストの冒険者🐉"