Locale-agnostic case conversions by default #KT-43023

libraries/stdlib/js/src/kotlin/text/char.kt

@@ -8,11 +8,79 @@ package kotlin.text
 // actually \s is enough to match all whitespace, but \xA0 added because of different regexp behavior of Rhino used in Selenium tests
 public actual fun Char.isWhitespace(): Boolean = toString().matches("[\\s\\xA0]")
 
+/**
+ * Converts this character to lower case using Unicode mapping rules of the invariant locale.
+ */
+@OptIn(ExperimentalStdlibApi::class)
 @kotlin.internal.InlineOnly
-public actual inline fun Char.toLowerCase(): Char = js("String.fromCharCode")(toInt()).toLowerCase().charCodeAt(0).unsafeCast<Int>().toChar()
+public actual inline fun Char.toLowerCase(): Char = lowercaseChar()
 
+/**
+ * Converts this character to lower case using Unicode mapping rules of the invariant locale.
+ *
+ * This function performs one-to-one character mapping.
+ * To support one-to-many character mapping use the [lowercase] function.
+ * If this character has no mapping equivalent, the character itself is returned.
+ *
+ * @sample samples.text.Chars.lowercase
+ */
+@SinceKotlin("1.4")
+@ExperimentalStdlibApi
 @kotlin.internal.InlineOnly
-public actual inline fun Char.toUpperCase(): Char = js("String.fromCharCode")(toInt()).toUpperCase().charCodeAt(0).unsafeCast<Int>().toChar()
+public actual inline fun Char.lowercaseChar(): Char = toString().asDynamic().toLowerCase().charCodeAt(0).unsafeCast<Int>().toChar()
+
+/**
+ * Converts this character to lower case using Unicode mapping rules of the invariant locale.
+ *
+ * This function supports one-to-many character mapping, thus the length of the returned string can be greater than one.
+ * For example, `'\u0130'.lowercase()` returns `"\u0069\u0307"`,
+ * where `'\u0130'` is the LATIN CAPITAL LETTER I WITH DOT ABOVE character (`İ`).
+ * If this character has no lower case mapping, the result of `toString()` of this char is returned.
+ *
+ * @sample samples.text.Chars.lowercase
+ */
+@SinceKotlin("1.4")
+@ExperimentalStdlibApi
+@kotlin.internal.InlineOnly
+public actual inline fun Char.lowercase(): String = toString().asDynamic().toLowerCase() as String
+
+/**
+ * Converts this character to upper case using Unicode mapping rules of the invariant locale.
+ */
+@OptIn(ExperimentalStdlibApi::class)
+@kotlin.internal.InlineOnly
+public actual inline fun Char.toUpperCase(): Char = uppercaseChar()
+
+/**
+ * Converts this character to upper case using Unicode mapping rules of the invariant locale.
+ *
+ * This function performs one-to-one character mapping.
+ * To support one-to-many character mapping use the [uppercase] function.
+ * If this character has no mapping equivalent, the character itself is returned.
+ *
+ * @sample samples.text.Chars.uppercase
+ */
+@SinceKotlin("1.4")
+@ExperimentalStdlibApi
+public actual fun Char.uppercaseChar(): Char {
+    val uppercase = uppercase()
+    return if (uppercase.length > 1) this else uppercase[0]
+}
+
+/**
+ * Converts this character to upper case using Unicode mapping rules of the invariant locale.
+ *
+ * This function supports one-to-many character mapping, thus the length of the returned string can be greater than one.
+ * For example, `'\uFB00'.uppercase()` returns `"\u0046\u0046"`,
+ * where `'\uFB00'` is the LATIN SMALL LIGATURE FF character (`ff`).
+ * If this character has no upper case mapping, the result of `toString()` of this char is returned.
+ *
+ * @sample samples.text.Chars.uppercase
+ */
+@SinceKotlin("1.4")
+@ExperimentalStdlibApi
+@kotlin.internal.InlineOnly
+public actual inline fun Char.uppercase(): String = toString().asDynamic().toUpperCase() as String
 
 /**
  * Returns `true` if this character is a Unicode high-surrogate code unit (also known as leading-surrogate code unit).

libraries/stdlib/js/src/kotlin/text/numberConversions.kt

@@ -17,8 +17,9 @@ public actual inline fun String.toBoolean(): Boolean = this.toBoolean()
 /**
  * Returns `true` if this string is not `null` and its content is equal to the word "true", ignoring case, and `false` otherwise.
  */
+@OptIn(ExperimentalStdlibApi::class)
 @SinceKotlin("1.4")
-public actual fun String?.toBoolean(): Boolean = this != null && this.toLowerCase() == "true"
+public actual fun String?.toBoolean(): Boolean = this != null && this.lowercase() == "true"
 
 /**
  * Parses the string as a signed [Byte] number and returns the result.
@@ -130,7 +131,8 @@ public actual inline fun Short.toString(radix: Int): String = this.toInt().toStr
 @SinceKotlin("1.2")
 public actual fun Int.toString(radix: Int): String = asDynamic().toString(checkRadix(radix))
 
-private fun String.isNaN(): Boolean = when (this.toLowerCase()) {
+@OptIn(ExperimentalStdlibApi::class)
+private fun String.isNaN(): Boolean = when (this.lowercase()) {
     "nan", "+nan", "-nan" -> true
     else -> false
 }

libraries/stdlib/js/src/kotlin/text/string.kt

@@ -168,20 +168,42 @@ public actual fun String.encodeToByteArray(
 
 /**
  * Returns a copy of this string converted to upper case using the rules of the default locale.
- *
- * @sample samples.text.Strings.toUpperCase
  */
 @kotlin.internal.InlineOnly
 public actual inline fun String.toUpperCase(): String = asDynamic().toUpperCase()
 
 /**
- * Returns a copy of this string converted to lower case using the rules of the default locale.
+ * Returns a copy of this string converted to upper case using Unicode mapping rules of the invariant locale.
  *
- * @sample samples.text.Strings.toLowerCase
+ * This function supports one-to-many and many-to-one character mapping,
+ * thus the length of the returned string can be different from the length of the original string.
+ *
+ * @sample samples.text.Strings.uppercase
+ */
+@SinceKotlin("1.4")
+@ExperimentalStdlibApi
+@kotlin.internal.InlineOnly
+public actual inline fun String.uppercase(): String = asDynamic().toUpperCase()
+
+/**
+ * Returns a copy of this string converted to lower case using the rules of the default locale.
  */
 @kotlin.internal.InlineOnly
 public actual inline fun String.toLowerCase(): String = asDynamic().toLowerCase()
 
+/**
+ * Returns a copy of this string converted to lower case using Unicode mapping rules of the invariant locale.
+ *
+ * This function supports one-to-many and many-to-one character mapping,
+ * thus the length of the returned string can be different from the length of the original string.
+ *
+ * @sample samples.text.Strings.lowercase
+ */
+@SinceKotlin("1.4")
+@ExperimentalStdlibApi
+@kotlin.internal.InlineOnly
+public actual inline fun String.lowercase(): String = asDynamic().toLowerCase()
+
 @kotlin.internal.InlineOnly
 internal actual inline fun String.nativeIndexOf(str: String, fromIndex: Int): Int = asDynamic().indexOf(str, fromIndex)
 
@@ -212,6 +234,7 @@ public inline fun String.match(regex: String): Array<String>? = asDynamic().matc
 @kotlin.internal.InlineOnly
 internal inline fun String.nativeReplace(pattern: RegExp, replacement: String): String = asDynamic().replace(pattern, replacement)
 
+@OptIn(ExperimentalStdlibApi::class)
 @SinceKotlin("1.2")
 @Suppress("ACTUAL_FUNCTION_WITH_DEFAULT_ARGUMENTS")
 public actual fun String.compareTo(other: String, ignoreCase: Boolean = false): Int {
@@ -226,11 +249,11 @@ public actual fun String.compareTo(other: String, ignoreCase: Boolean = false):
             var s1 = this.substring(start, end)
             var s2 = other.substring(start, end)
             if (s1 != s2) {
-                s1 = s1.toUpperCase()
-                s2 = s2.toUpperCase()
+                s1 = s1.uppercase()
+                s2 = s2.uppercase()
                 if (s1 != s2) {
-                    s1 = s1.toLowerCase()
-                    s2 = s2.toLowerCase()
+                    s1 = s1.lowercase()
+                    s2 = s2.lowercase()
                     if (s1 != s2) {
                         return s1.compareTo(s2)
                     }

libraries/stdlib/js/src/kotlin/text/stringsCode.kt

@@ -54,6 +54,7 @@ public fun String.matches(regex: String): Boolean {
 
 public actual fun CharSequence.isBlank(): Boolean = length == 0 || (if (this is String) this else this.toString()).matches("^[\\s\\xA0]+$")
 
+@OptIn(ExperimentalStdlibApi::class)
 @Suppress("ACTUAL_FUNCTION_WITH_DEFAULT_ARGUMENTS")
 public actual fun String?.equals(other: String?, ignoreCase: Boolean = false): Boolean =
     if (this == null)
@@ -61,7 +62,7 @@ public actual fun String?.equals(other: String?, ignoreCase: Boolean = false): B
     else if (!ignoreCase)
         this == other
     else
-        other != null && this.toLowerCase() == other.toLowerCase()
+        other != null && this.lowercase() == other.lowercase()
 
 
 @Suppress("ACTUAL_FUNCTION_WITH_DEFAULT_ARGUMENTS")