palindrome.go

benchmarks

BenchmarkIsPalindrome5Chars-8       	100000000	        19.8 ns/op
BenchmarkIsPalindrome10Chars-8      	50000000	        27.2 ns/op
BenchmarkIsPalindrome20Chars-8      	30000000	        48.1 ns/op
BenchmarkIsPalindrome40Chars-8      	20000000	       112 ns/op
BenchmarkIsPalindrome80Chars-8      	 5000000	       337 ns/op
BenchmarkIsPalindromeFalsy-8        	100000000	        13.8 ns/op
BenchmarkIsPalindromeFalsyVeryLong-8	 2000000	       709 ns/op

palindrome.go

package tests

func IsPalindrome(text string) bool {
	charLen := len(text)
	bytes := []byte(text)

	var byteLeft, byteRight byte

	for i, j := 0, charLen-1; i < charLen; i++ {
		byteLeft = bytes[i]
		if byteLeft < 'A' || byteLeft > 'z' || (byteLeft > 'Z' && byteLeft < 'a') {
			continue
		}

		for {
			byteRight = bytes[j]
			j--

			if byteRight < 'A' || byteRight > 'z' || (byteRight > 'Z' && byteRight < 'a') {
				continue
			}

			if byteLeft != byteRight && byteLeft-32 != byteRight && byteLeft+32 != byteRight {
				return false
			}

			break;
		}

		if i >= j {
			break
		}
	}

	return true
}

palindrome_test.go

package tests

import (
	"testing"
	"strings"
)

func TestIsPalindrome(t *testing.T) {
	var inputs map[string]bool = map[string]bool{
		"No 'X' in Nixon": true,
		"Step on no Pets": true,
		"Taco cat": true,
		"TacO cat Taco  CAt": true,
		"Stack cats": true,
		"Amor, Roma": true,
		"NommmoN": true,
		"Mom Mom Mom Mom Mom Mom\" Mom Mom` Mom _Mom Mom -MomMom": true,
		"Noooooooom ooooooooN": true,
		"A": true,
		"Aa": true,
		"NommnoN": false,
		"No X on Nixon": false,
		"Nixon Nixon": false,
		"Step on Pets": false,
	}

	for input, expectedOutput := range inputs {
		if IsPalindrome(input) != expectedOutput {
			t.Errorf("IsPalindrome(%s) was expected to be %#v.", input, expectedOutput)
		}
	}
}

func BenchmarkIsPalindrome5Chars(b *testing.B) {
	for i := 0; i < b.N; i++ {
		IsPalindrome("ooooo")
	}
}

func BenchmarkIsPalindrome10Chars(b *testing.B) {
	for i := 0; i < b.N; i++ {
		IsPalindrome("Ta co ca T")
	}
}

func BenchmarkIsPalindrome20Chars(b *testing.B) {
	for i := 0; i < b.N; i++ {
		IsPalindrome("Noooooooom ooooooooN")
	}
}

func BenchmarkIsPalindrome40Chars(b *testing.B) {
	for i := 0; i < b.N; i++ {
		IsPalindrome("Mo m Mom Mom Mom Mom Mom Mom Mom Mom Mom")
	}
}

func BenchmarkIsPalindrome80Chars(b *testing.B) {
	for i := 0; i < b.N; i++ {
		IsPalindrome(strings.Repeat("A", 80))
	}
}

func BenchmarkIsPalindromeFalsy(b *testing.B) {
	for i := 0; i < b.N; i++ {
		IsPalindrome("Not a palindrome")
	}
}

func BenchmarkIsPalindromeFalsyVeryLong(b *testing.B) {
	for i := 0; i < b.N; i++ {
		IsPalindrome(strings.Repeat("N", 500) + "o")
	}
}