mirror of
https://github.com/mrkkrp/megaparsec.git
synced 2024-12-18 22:01:41 +03:00
190 lines
6.6 KiB
Haskell
190 lines
6.6 KiB
Haskell
--
|
||
-- QuickCheck tests for Megaparsec's expression parsers.
|
||
--
|
||
-- Copyright © 2015–2016 Megaparsec contributors
|
||
--
|
||
-- Redistribution and use in source and binary forms, with or without
|
||
-- modification, are permitted provided that the following conditions are
|
||
-- met:
|
||
--
|
||
-- * Redistributions of source code must retain the above copyright notice,
|
||
-- this list of conditions and the following disclaimer.
|
||
--
|
||
-- * Redistributions in binary form must reproduce the above copyright
|
||
-- notice, this list of conditions and the following disclaimer in the
|
||
-- documentation and/or other materials provided with the distribution.
|
||
--
|
||
-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS “AS IS” AND ANY
|
||
-- EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
|
||
-- WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
|
||
-- DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
|
||
-- DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
||
-- DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
||
-- OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
||
-- HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
|
||
-- STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
|
||
-- ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
||
-- POSSIBILITY OF SUCH DAMAGE.
|
||
|
||
{-# LANGUAGE CPP #-}
|
||
{-# LANGUAGE FlexibleContexts #-}
|
||
{-# LANGUAGE TypeFamilies #-}
|
||
|
||
module Expr (tests) where
|
||
|
||
import Control.Applicative (some, (<|>))
|
||
import Data.Char (isDigit, digitToInt)
|
||
|
||
import Test.Framework
|
||
import Test.Framework.Providers.QuickCheck2 (testProperty)
|
||
import Test.QuickCheck
|
||
|
||
import Text.Megaparsec.Char
|
||
import Text.Megaparsec.Combinator
|
||
import Text.Megaparsec.Expr
|
||
import Text.Megaparsec.Prim
|
||
|
||
import Util
|
||
|
||
#if !MIN_VERSION_base(4,8,0)
|
||
import Control.Applicative ((<$>), (<*), (<*>), (*>), pure)
|
||
#endif
|
||
|
||
tests :: Test
|
||
tests = testGroup "Expression parsers"
|
||
[ testProperty "correctness of expression parser" prop_correctness
|
||
, testProperty "error message on empty input" prop_empty_error
|
||
, testProperty "error message on missing term" prop_missing_term
|
||
, testProperty "error message on missing op" prop_missing_op ]
|
||
|
||
-- Algebraic structures to build abstract syntax tree of our expression.
|
||
|
||
data Node
|
||
= Val Integer -- ^ literal value
|
||
| Neg Node -- ^ negation (prefix unary)
|
||
| Fac Node -- ^ factorial (postfix unary)
|
||
| Mod Node Node -- ^ modulo
|
||
| Sum Node Node -- ^ summation (addition)
|
||
| Sub Node Node -- ^ subtraction
|
||
| Pro Node Node -- ^ product
|
||
| Div Node Node -- ^ division
|
||
| Exp Node Node -- ^ exponentiation
|
||
deriving (Eq, Show)
|
||
|
||
instance Enum Node where
|
||
fromEnum (Val _) = 0
|
||
fromEnum (Neg _) = 0
|
||
fromEnum (Fac _) = 0
|
||
fromEnum (Mod _ _) = 0
|
||
fromEnum (Exp _ _) = 1
|
||
fromEnum (Pro _ _) = 2
|
||
fromEnum (Div _ _) = 2
|
||
fromEnum (Sum _ _) = 3
|
||
fromEnum (Sub _ _) = 3
|
||
toEnum _ = error "Oops!"
|
||
|
||
instance Ord Node where
|
||
x `compare` y = fromEnum x `compare` fromEnum y
|
||
|
||
showNode :: Node -> String
|
||
showNode (Val x) = show x
|
||
showNode n@(Neg x) = "-" ++ showGT n x
|
||
showNode n@(Fac x) = showGT n x ++ "!"
|
||
showNode n@(Mod x y) = showGE n x ++ " % " ++ showGE n y
|
||
showNode n@(Sum x y) = showGT n x ++ " + " ++ showGE n y
|
||
showNode n@(Sub x y) = showGT n x ++ " - " ++ showGE n y
|
||
showNode n@(Pro x y) = showGT n x ++ " * " ++ showGE n y
|
||
showNode n@(Div x y) = showGT n x ++ " / " ++ showGE n y
|
||
showNode n@(Exp x y) = showGE n x ++ " ^ " ++ showGT n y
|
||
|
||
showGT :: Node -> Node -> String
|
||
showGT parent node = (if node > parent then showCmp else showNode) node
|
||
|
||
showGE :: Node -> Node -> String
|
||
showGE parent node = (if node >= parent then showCmp else showNode) node
|
||
|
||
showCmp :: Node -> String
|
||
showCmp node = (if fromEnum node == 0 then showNode else inParens) node
|
||
|
||
inParens :: Node -> String
|
||
inParens x = "(" ++ showNode x ++ ")"
|
||
|
||
instance Arbitrary Node where
|
||
arbitrary = sized arbitraryN0
|
||
|
||
arbitraryN0 :: Int -> Gen Node
|
||
arbitraryN0 n = frequency [ (1, Mod <$> leaf <*> leaf)
|
||
, (9, arbitraryN1 n) ]
|
||
where leaf = arbitraryN1 (n `div` 2)
|
||
|
||
arbitraryN1 :: Int -> Gen Node
|
||
arbitraryN1 n =
|
||
frequency [ (1, Neg <$> arbitraryN2 n)
|
||
, (1, Fac <$> arbitraryN2 n)
|
||
, (7, arbitraryN2 n)]
|
||
|
||
arbitraryN2 :: Int -> Gen Node
|
||
arbitraryN2 0 = Val . getNonNegative <$> arbitrary
|
||
arbitraryN2 n = elements [Sum,Sub,Pro,Div,Exp] <*> leaf <*> leaf
|
||
where leaf = arbitraryN0 (n `div` 2)
|
||
|
||
-- Some helpers are put here since we don't want to depend on
|
||
-- "Text.Megaparsec.Lexer".
|
||
|
||
lexeme :: (MonadParsec e s m, Token s ~ Char) => m a -> m a
|
||
lexeme p = p <* hidden space
|
||
|
||
symbol :: (MonadParsec e s m, Token s ~ Char) => String -> m String
|
||
symbol = lexeme . string
|
||
|
||
parens :: (MonadParsec e s m, Token s ~ Char) => m a -> m a
|
||
parens = between (symbol "(") (symbol ")")
|
||
|
||
integer :: (MonadParsec e s m, Token s ~ Char) => m Integer
|
||
integer = lexeme (read <$> some digitChar <?> "integer")
|
||
|
||
-- Here we use table of operators that makes use of all features of
|
||
-- 'makeExprParser'. Then we generate abstract syntax tree (AST) of complex
|
||
-- but valid expressions and render them to get their textual
|
||
-- representation.
|
||
|
||
expr :: (MonadParsec e s m, Token s ~ Char) => m Node
|
||
expr = makeExprParser term table
|
||
|
||
term :: (MonadParsec e s m, Token s ~ Char) => m Node
|
||
term = parens expr <|> (Val <$> integer) <?> "term"
|
||
|
||
table :: (MonadParsec e s m, Token s ~ Char) => [[Operator m Node]]
|
||
table = [ [ Prefix (symbol "-" *> pure Neg)
|
||
, Postfix (symbol "!" *> pure Fac)
|
||
, InfixN (symbol "%" *> pure Mod) ]
|
||
, [ InfixR (symbol "^" *> pure Exp) ]
|
||
, [ InfixL (symbol "*" *> pure Pro)
|
||
, InfixL (symbol "/" *> pure Div) ]
|
||
, [ InfixL (symbol "+" *> pure Sum)
|
||
, InfixL (symbol "-" *> pure Sub)] ]
|
||
|
||
prop_correctness :: Node -> Property
|
||
prop_correctness node = checkParser expr (Right node) (showNode node)
|
||
|
||
prop_empty_error :: Property
|
||
prop_empty_error = checkParser expr r s
|
||
where r = posErr 0 s [ueof, elabel "term"]
|
||
s = ""
|
||
|
||
prop_missing_term :: Char -> Property
|
||
prop_missing_term c = checkParser expr r s
|
||
where r | c `elem` "-(" = posErr 1 s [ueof, elabel "term"]
|
||
| isDigit c = Right . Val . fromIntegral . digitToInt $ c
|
||
| otherwise = posErr 0 s [utok c, elabel "term"]
|
||
s = pure c
|
||
|
||
prop_missing_op :: Node -> Node -> Property
|
||
prop_missing_op a b = checkParser expr r s
|
||
where a' = inParens a
|
||
c = s !! n
|
||
n = succ $ length a'
|
||
r | c == '-' = Right $ Sub a b
|
||
| otherwise = posErr n s [utok c, eeof, elabel "operator"]
|
||
s = a' ++ " " ++ inParens b
|