megaparsec/tests/Combinator.hs

--
-- QuickCheck tests for Megaparsec's generic parser combinators.
--
-- Copyright © 2015–2016 Megaparsec contributors
--
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module Combinator (tests) where

import Control.Applicative
import Data.Char (isLetter, isDigit)
import Data.List (intersperse)
import Data.Maybe (fromMaybe, maybeToList, isNothing, fromJust)

import Test.Framework
import Test.Framework.Providers.QuickCheck2 (testProperty)
import Test.QuickCheck

import Text.Megaparsec.Char
import Text.Megaparsec.Combinator

import Util

tests :: Test
tests = testGroup "Generic parser combinators"
  [ testProperty "combinator between"   prop_between
  , testProperty "combinator choice"    prop_choice
  , testProperty "combinator count"     prop_count
  , testProperty "combinator count'"    prop_count'
  , testProperty "combinator eitherP"   prop_eitherP
  , testProperty "combinator endBy"     prop_endBy
  , testProperty "combinator endBy1"    prop_endBy1
  , testProperty "combinator manyTill"  prop_manyTill
  , testProperty "combinator someTill"  prop_someTill
  , testProperty "combinator option"    prop_option
  , testProperty "combinator sepBy"     prop_sepBy
  , testProperty "combinator sepBy1"    prop_sepBy1
  , testProperty "combinator sepEndBy"  prop_sepEndBy
  , testProperty "combinator sepEndBy1" prop_sepEndBy1
  , testProperty "combinator skipMany"  prop_skipMany
  , testProperty "combinator skipSome"  prop_skipSome ]

prop_between :: String -> Char -> NonNegative Int -> String -> Property
prop_between pre c n' post = checkParser p r s
  where p = between (string pre) (string post) (many (char c))
        n = getNonNegative n'
        b = length $ takeWhile (== c) post
        r | b > 0 = posErr (length pre + n + b) s $ exStr post :
                    if length post == b
                    then [uneEof, exCh c]
                    else [uneCh (post !! b), exCh c]
          | otherwise = Right z
        z = replicate n c
        s = pre ++ z ++ post

prop_choice :: NonEmptyList Char -> Char -> Property
prop_choice cs' s' = checkParser p r s
  where cs = getNonEmpty cs'
        p = choice $ char <$> cs
        r | s' `elem` cs = Right s'
          | otherwise    = posErr 0 s $ uneCh s' : (exCh <$> cs)
        s = [s']

prop_count :: Int -> NonNegative Int -> Property
prop_count n x' = checkParser p r s
  where x = getNonNegative x'
        p = count n (char 'x')
        r = simpleParse (count' n n (char 'x')) s
        s = replicate x 'x'

prop_count' :: Int -> Int -> NonNegative Int -> Property
prop_count' m n x' = checkParser p r s
  where x = getNonNegative x'
        p = count' m n (char 'x')
        r | n <= 0 || m > n  =
              if x == 0
              then Right ""
              else posErr 0 s [uneCh 'x', exEof]
          | m <= x && x <= n = Right s
          | x < m            = posErr x s [uneEof, exCh 'x']
          | otherwise        = posErr n s [uneCh 'x', exEof]
        s = replicate x 'x'

prop_eitherP :: Char -> Property
prop_eitherP ch = checkParser p r s
  where p = eitherP letterChar digitChar
        r | isLetter ch = Right (Left  ch)
          | isDigit  ch = Right (Right ch)
          | otherwise   = posErr 0 s [uneCh ch, exSpec "letter", exSpec "digit"]
        s = pure ch

prop_endBy :: NonNegative Int -> Char -> Property
prop_endBy n' c = checkParser p r s
  where n = getNonNegative n'
        p = endBy (char 'a') (char '-')
        r | c == 'a' && n == 0 = posErr 1 s [uneEof, exCh '-']
          | c == 'a'           = posErr (g n) s [uneCh 'a', exCh '-']
          | c == '-' && n == 0 = posErr 0 s [uneCh '-', exCh 'a', exEof]
          | c /= '-'           = posErr (g n) s $ uneCh c :
                                 (if n > 0 then exCh '-' else exEof) :
                                 [exCh 'a' | n == 0]
          | otherwise = Right (replicate n 'a')
        s = intersperse '-' (replicate n 'a') ++ [c]

prop_endBy1 :: NonNegative Int -> Char -> Property
prop_endBy1 n' c = checkParser p r s
  where n = getNonNegative n'
        p = endBy1 (char 'a') (char '-')
        r | c == 'a' && n == 0 = posErr 1 s [uneEof, exCh '-']
          | c == 'a'           = posErr (g n) s [uneCh 'a', exCh '-']
          | c == '-' && n == 0 = posErr 0 s [uneCh '-', exCh 'a']
          | c /= '-'           = posErr (g n) s $ uneCh c :
                                 [exCh '-' | n > 0] ++
                                 [exCh 'a' | n == 0]
          | otherwise = Right (replicate n 'a')
        s = intersperse '-' (replicate n 'a') ++ [c]

prop_manyTill :: NonNegative Int -> NonNegative Int
              -> NonNegative Int -> Property
prop_manyTill a' b' c' = checkParser p r s
  where [a,b,c] = getNonNegative <$> [a',b',c']
        p = (,) <$> manyTill letterChar (char 'c') <*> many letterChar
        r | c == 0    = posErr (a + b) s [uneEof, exCh 'c', exSpec "letter"]
          | otherwise = let (pre, post) = break (== 'c') s
                        in Right (pre, drop 1 post)
        s = abcRow a b c

prop_someTill :: NonNegative Int -> NonNegative Int
              -> NonNegative Int -> Property
prop_someTill a' b' c' = checkParser p r s
  where [a,b,c] = getNonNegative <$> [a',b',c']
        p = (,) <$> someTill letterChar (char 'c') <*> many letterChar
        r | null s    = posErr 0 s [uneEof, exSpec "letter"]
          | c == 0    = posErr (a + b) s [uneEof, exCh 'c', exSpec "letter"]
          | s == "c"  = posErr 1 s [uneEof, exCh 'c', exSpec "letter"]
          | head s == 'c' = Right ("c", drop 2 s)
          | otherwise = let (pre, post) = break (== 'c') s
                        in Right (pre, drop 1 post)
        s = abcRow a b c

prop_option :: String -> String -> String -> Property
prop_option d a s = checkParser p r s
  where p = option d (string a)
        r = simpleParse (fromMaybe d <$> optional (string a)) s

prop_sepBy :: NonNegative Int -> Maybe Char -> Property
prop_sepBy n' c' = checkParser p r s
  where n = getNonNegative n'
        c = fromJust c'
        p = sepBy (char 'a') (char '-')
        r | isNothing c' = Right (replicate n 'a')
          | c == 'a' && n == 0 = Right "a"
          | n == 0    = posErr 0 s [uneCh c, exCh 'a', exEof]
          | c == '-'  = posErr (length s) s [uneEof, exCh 'a']
          | otherwise = posErr (g n) s [uneCh c, exCh '-', exEof]
        s = intersperse '-' (replicate n 'a') ++ maybeToList c'

prop_sepBy1 :: NonNegative Int -> Maybe Char -> Property
prop_sepBy1 n' c' = checkParser p r s
  where n = getNonNegative n'
        c = fromJust c'
        p = sepBy1 (char 'a') (char '-')
        r | isNothing c' && n >= 1 = Right (replicate n 'a')
          | isNothing c' = posErr 0 s [uneEof, exCh 'a']
          | c == 'a' && n == 0 = Right "a"
          | n == 0    = posErr 0 s [uneCh c, exCh 'a']
          | c == '-'  = posErr (length s) s [uneEof, exCh 'a']
          | otherwise = posErr (g n) s [uneCh c, exCh '-', exEof]
        s = intersperse '-' (replicate n 'a') ++ maybeToList c'

prop_sepEndBy :: NonNegative Int -> Maybe Char -> Property
prop_sepEndBy n' c' = checkParser p r s
  where n = getNonNegative n'
        c = fromJust c'
        p = sepEndBy (char 'a') (char '-')
        a = Right $ replicate n 'a'
        r | isNothing c' = a
          | c == 'a' && n == 0 = Right "a"
          | n == 0    = posErr 0 s [uneCh c, exCh 'a', exEof]
          | c == '-'  = a
          | otherwise = posErr (g n) s [uneCh c, exCh '-', exEof]
        s = intersperse '-' (replicate n 'a') ++ maybeToList c'

prop_sepEndBy1 :: NonNegative Int -> Maybe Char -> Property
prop_sepEndBy1 n' c' = checkParser p r s
  where n = getNonNegative n'
        c = fromJust c'
        p = sepEndBy1 (char 'a') (char '-')
        a = Right $ replicate n 'a'
        r | isNothing c' && n >= 1 = a
          | isNothing c' = posErr 0 s [uneEof, exCh 'a']
          | c == 'a' && n == 0 = Right "a"
          | n == 0    = posErr 0 s [uneCh c, exCh 'a']
          | c == '-'  = a
          | otherwise = posErr (g n) s [uneCh c, exCh '-', exEof]
        s = intersperse '-' (replicate n 'a') ++ maybeToList c'

prop_skipMany :: Char -> NonNegative Int -> String -> Property
prop_skipMany c n' a = checkParser p r s
  where p = skipMany (char c) *> string a
        n = getNonNegative n'
        r = simpleParse (many (char c) >> string a) s
        s = replicate n c ++ a

prop_skipSome :: Char -> NonNegative Int -> String -> Property
prop_skipSome c n' a = checkParser p r s
  where p = skipSome (char c) *> string a
        n = getNonNegative n'
        r = simpleParse (some (char c) >> string a) s
        s = replicate n c ++ a

g :: Int -> Int
g x = x + if x > 0 then x - 1 else 0