added capitalize/decapitalize of strings and isUpper/LowerCase helpers to Char

libraries/stdlib/src/kotlin/Char.kt

@@ -25,3 +25,12 @@ public inline fun Char.isJavaLetterOrDigit(): Boolean = Character.isJavaLetterOr
  */
 public inline fun Char.isWhitespace(): Boolean = Character.isWhitespace(this)
 
+/**
+ * Returns true if this character is upper case
+ */
+public inline fun Char.isUpperCase(): Boolean = Character.isUpperCase(this)
+
+/**
+ * Returns true if this character is lower case
+ */
+public inline fun Char.isLowerCase(): Boolean = Character.isLowerCase(this)

libraries/stdlib/src/kotlin/Strings.kt

@@ -35,6 +35,24 @@ public inline fun String.trimLeading(prefix: String): String {
     return answer
 }
 
+/**
+ * Returns a copy of this string capitalised if it is not empty or already starting with an uppper case letter, otherwise returns this
+ *
+ * @includeFunctionBody ../../test/StringTest.kt capitalize
+ */
+public inline fun String.capitalize(): String {
+    return if (notEmpty() && charAt(0).isLowerCase()) substring(0, 1).toUpperCase() + substring(1) else this
+}
+
+/**
+ * Returns a copy of this string with the first letter lower case if it is not empty or already starting with a lower case letter, otherwise returns this
+ *
+ * @includeFunctionBody ../../test/StringTest.kt decapitalize
+ */
+public inline fun String.decapitalize(): String {
+    return if (notEmpty() && charAt(0).isUpperCase()) substring(0, 1).toLowerCase() + substring(1) else this
+}
+
 /** Returns the string with the trailing postfix of this string removed */
 public inline fun String.trimTrailing(postfix: String): String {
     var answer = this

libraries/stdlib/test/StringTest.kt

@@ -78,4 +78,19 @@ class StringTest {
         assertFalse("".endsWith('a'))
     }
 
+    test fun capitalize() {
+        assertEquals("A", "A".capitalize())
+        assertEquals("A", "a".capitalize())
+        assertEquals("Abcd", "abcd".capitalize())
+        assertEquals("Abcd", "Abcd".capitalize())
+    }
+
+    test fun decapitalize() {
+        assertEquals("a", "A".decapitalize())
+        assertEquals("a", "a".decapitalize())
+        assertEquals("abcd", "abcd".decapitalize())
+        assertEquals("abcd", "Abcd".decapitalize())
+        assertEquals("uRL", "URL".decapitalize())
+    }
+
 }