Add ir interpreter tests

compiler/testData/ir/interpreter/helpers/Strings.kt

@@ -0,0 +1,84 @@
+@file:kotlin.jvm.JvmMultifileClass
+@file:kotlin.jvm.JvmName("StringsKt")
+
+package kotlin.text
+
+public inline fun CharSequence.trim(predicate: (Char) -> Boolean): CharSequence {
+    var startIndex = 0
+    var endIndex = length - 1
+    var startFound = false
+
+    while (startIndex <= endIndex) {
+        val index = if (!startFound) startIndex else endIndex
+        val match = predicate(this[index])
+
+        if (!startFound) {
+            if (!match)
+                startFound = true
+            else
+                startIndex += 1
+        } else {
+            if (!match)
+                break
+            else
+                endIndex -= 1
+        }
+    }
+
+    return subSequence(startIndex, endIndex + 1)
+}
+
+public fun CharSequence.trim(): CharSequence = trim(Char::isWhitespace)
+
+public inline fun String.trim(): String = (this as CharSequence).trim().toString()
+
+public inline fun CharSequence.isEmpty(): Boolean = length == 0
+
+public inline fun CharSequence.isNotEmpty(): Boolean = length > 0
+
+public operator fun CharSequence.iterator(): CharIterator = object : CharIterator() {
+    private var index = 0
+
+    public override fun nextChar(): Char = get(index++)
+
+    public override fun hasNext(): Boolean = index < length
+}
+
+public fun CharSequence.first(): Char {
+    if (isEmpty())
+        throw NoSuchElementException("Char sequence is empty.")
+    return this[0]
+}
+
+public val CharSequence.indices: IntRange
+    get() = 0..length - 1
+
+public val CharSequence.lastIndex: Int
+    get() = this.length - 1
+
+public inline fun CharSequence.substring(startIndex: Int, endIndex: Int = length): String = subSequence(startIndex, endIndex).toString()
+
+public fun CharSequence.substring(range: IntRange): String = subSequence(range.start, range.endInclusive + 1).toString()
+
+public inline fun CharSequence.elementAtOrElse(index: Int, defaultValue: (Int) -> Char): Char {
+    return if (index >= 0 && index <= lastIndex) get(index) else defaultValue(index)
+}
+
+public fun CharSequence.toList(): List<Char> {
+    return when (length) {
+        0 -> emptyList()
+        1 -> listOf(this[0])
+        else -> this.toMutableList()
+    }
+}
+
+public fun CharSequence.toMutableList(): MutableList<Char> {
+    return toCollection(ArrayList<Char>(length))
+}
+
+public fun <C : MutableCollection<in Char>> CharSequence.toCollection(destination: C): C {
+    for (item in this) {
+        destination.add(item)
+    }
+    return destination
+}