whitespace tolerance

src/Lib.hs

@@ -1,5 +1,5 @@
 module Lib
-    ( exprparser, evaluate, replaceVars, Expr, extractVariableDefinitions, updateVariables
+    ( exprparser, evaluate, replaceVars, Expr, extractVariableDefinitions, updateVariables, parseFullString
     ) where
 import Control.Applicative((<*))
 
@@ -40,11 +40,14 @@ TokenParser{ parens = m_parens
            , integer    = m_integer
            , whiteSpace = m_whiteSpace } = makeTokenParser def
 
+parseFullString s = parse (m_whiteSpace *> exprparser <* eof) "<stdin>" s
+
 exprparser :: Parser Expr
 exprparser = buildExpressionParser table term <?> "expression"
 
 table = [
             [
+                Infix (m_reservedOp "^" >> return (Binary Power)) AssocLeft,
                 Infix (m_reservedOp "^" >> return (Binary Power)) AssocLeft
             ],
             [
@@ -59,7 +62,9 @@ table = [
 
 constantInteger :: Parser Rational
 constantInteger = try (do
+        _ <- m_whiteSpace
         n <- m_integer
+        _ <- m_whiteSpace
         notFollowedBy . char $ '.'
         return (n % 1)
     )
@@ -68,7 +73,9 @@ constantRational :: Parser Rational
 constantRational = do
     natural        <- m_natural
     _              <- char '.'
-    decimal_digits <- many digit
+    _              <- m_whiteSpace
+    decimal_digits <- many1 digit
+    _              <- m_whiteSpace
     let decimal = read decimal_digits :: Integer
     let natural_length = length . show $ natural
     let decimal_length = length decimal_digits
@@ -137,9 +144,10 @@ rationalPower a b = rationalPower' (numerator a, denominator a) (numerator b, de
 
 evaluate :: Expr -> Rational
 evaluate (Constant c) = c
-evaluate (Binary Plus     a b) = evaluate a + evaluate b
-evaluate (Binary Minus    a b) = evaluate a - evaluate b
-evaluate (Binary Divide   a b) = evaluate a / evaluate b
-evaluate (Binary Multiply a b) = evaluate a * evaluate b
-evaluate (Binary Power    a b) = rationalPower (evaluate a) (evaluate b)
-evaluate (Variable _)          = error "Unreachable Code"
+evaluate (Binary Plus     a b)    = evaluate a + evaluate b
+evaluate (Binary Minus    a b)    = evaluate a - evaluate b
+evaluate (Binary Divide   a b)    = evaluate a / evaluate b
+evaluate (Binary Multiply a b)    = evaluate a * evaluate b
+evaluate (Binary Power    a b)    = rationalPower (evaluate a) (evaluate b)
+evaluate (VariableDefinition _ _) = error "Unreachable Code"
+evaluate (Variable _)             = error "Unreachable Code"