strings: add IsPalindrome (#50)

Author: mgstabrani

DIRECTORY.md

@@ -36,4 +36,5 @@
 
 ## Strings
 - [Issubsequence](strings/issubsequence.jule)
+- [Palindrome](strings/palindrome.jule)
 - [Reverse](strings/reverse.jule)

strings/palindrome.jule

@@ -0,0 +1,10 @@
+fn IsPalindrome(s: string): bool {
+	mut runes := []rune(s)
+	mut i, mut j := 0, len(runes)-1
+	for i < j; i, j = i+1, j-1 {
+		if runes[i] != runes[j] {
+			return false
+		}
+	}
+	return true
+}

strings/palindrome_test.jule

@@ -0,0 +1,52 @@
+#build test
+
+use "std/testing"
+
+struct palindromeTest {
+	name:     string
+	s:        string
+	expected: bool
+}
+
+let palindromeTests: []palindromeTest = [
+	{
+		"Simple palindrome",
+		"madam",
+		true,
+	},
+	{
+		"Simple non-palindrome",
+		"hello",
+		false,
+	},
+	{
+		"Empty string",
+		"",
+		true,
+	},
+	{
+		"Single character",
+		"a",
+		true,
+	},
+	{
+		"Even length palindrome",
+		"abba",
+		true,
+	},
+	{
+		"Case sensitive mismatch",
+		"Madam",
+		false,
+	},
+]
+
+#test
+fn testIsPalindrome(t: &testing::T) {
+	for _, test in palindromeTests {
+		funcResult := IsPalindrome(test.s)
+		if test.expected != funcResult {
+			t.Errorf("expected: {}, got {}", test.expected, funcResult)
+		}
+	}
+}