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## to Bracket Push in the PureScript Track

Published at Apr 05 2020 · 0 comments
Instructions
Test suite
Solution

Given a string containing brackets [], braces {} and parentheses (), verify that all the pairs are matched and nested correctly.

Ginna Baker

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### Main.purs

module Test.Main where

import Prelude

import Effect (Effect)
import Test.Unit.Assert as Assert
import Test.Unit (TestSuite, suite, test)
import Test.Unit.Main (runTest)
import BracketPush (isPaired)

main :: Effect Unit
main = runTest suites

suites :: TestSuite
suites = do
suite "BracketPush.isPaired" do

test "paired square brackets" $Assert.equal true (isPaired "[]") test "empty string"$
Assert.equal true
(isPaired "")

test "unpaired brackets" $Assert.equal false (isPaired "[[") test "wrong ordered brackets"$
Assert.equal false
(isPaired "}{")

test "paired with whitespace" $Assert.equal true (isPaired "{ }") test "simple nested brackets"$
Assert.equal true
(isPaired "{[]}")

test "several paired brackets" $Assert.equal true (isPaired "{}[]") test "paired and nested brackets"$
Assert.equal true
(isPaired "([{}({}[])])")

test "unopened closing brackets" $Assert.equal false (isPaired "{[)][]}") test "unpaired and nested brackets"$
Assert.equal false
(isPaired "([{])")

test "paired and wrong nested brackets" $Assert.equal false (isPaired "[({]})") test "math expression"$
Assert.equal true
(isPaired "(((185 + 223.85) * 15) - 543)/2")

test "complex latex expression" $Assert.equal true (isPaired "\\left(\\begin{array}{cc} \\frac{1}{3} & x\\\\ \\mathrm{e}^{x} &... x^2 \\end{array}\\right)") module BracketPush ( isPaired ) where import Prelude hiding (between) import Control.Lazy (fix) import Data.Array (many) import Data.Either (isRight) import Text.Parsing.Parser (runParser) import Text.Parsing.Parser.Combinators (between, choice, skipMany) import Text.Parsing.Parser.String (eof, noneOf, string) isPaired ∷ String → Boolean isPaired s = isRight$ runParser s $fix go *> eof where skip = skipMany$ noneOf ['{','}','[',']','(',')']
go p = (skip *> _)
$many$ choice
[ between (string "{") (string "}") p
, between (string "[") (string "]") p
, between (string "(") (string ")") p
]
*> skip

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