first Kotlin version

src/main/kotlin/mods/octarinecore/Utils.kt

@@ -0,0 +1,70 @@
+@file:JvmName("Utils")
+@file:Suppress("NOTHING_TO_INLINE")
+package mods.octarinecore
+
+import net.minecraft.util.ResourceLocation
+import kotlin.reflect.KProperty
+import java.lang.Math.*
+
+const val PI2 = 2.0 * PI
+
+inline fun String.stripStart(str: String) = if (startsWith(str)) substring(str.length) else this
+inline fun ResourceLocation.stripStart(str: String) = ResourceLocation(resourceDomain, resourcePath.stripStart(str))
+
+/** Mutating version of _map_. Replace each element of the list with the result of the given transformation. */
+inline fun <reified T> MutableList<T>.replace(transform: (T) -> T) = forEachIndexed { idx, value -> this[idx] = transform(value) }
+
+/** Exchange the two elements of the list with the given indices */
+inline fun <T> MutableList<T>.exchange(idx1: Int, idx2: Int) {
+    val e = this[idx1]
+    this[idx1] = this[idx2]
+    this[idx2] = e
+}
+
+/** Cross product of this [Iterable] with the parameter. */
+fun <A, B> Iterable<A>.cross(other: Iterable<B>) = flatMap { a -> other.map { b -> a to b } }
+
+/**
+ * Property-level delegate backed by a [ThreadLocal].
+ *
+ * @param[init] Lambda to get initial value
+ */
+class ThreadLocalDelegate<T>(init: () -> T) {
+    var tlVal = ThreadLocal.withInitial(init)
+    operator fun getValue(thisRef: Any?, property: KProperty<*>): T = tlVal.get()
+    operator fun setValue(thisRef: Any?, property: KProperty<*>, value: T) { tlVal.set(value) }
+}
+
+/**
+ * Starting with the second element of this [Iterable] until the last, call the supplied lambda with
+ * the parameters (index, element, previous element).
+ */
+inline fun <reified T> Iterable<T>.forEachPairIndexed(func: (Int, T, T)->Unit) {
+    var previous: T? = null
+    forEachIndexed { idx, current ->
+        if (previous != null) func(idx, current, previous!!)
+        previous = current
+    }
+}
+
+/** Call the supplied lambda and return its result, or the given default value if an exception is thrown. */
+fun <T> tryDefault(default: T, work: ()->T) = try { work() } catch (e: Throwable) { default }
+
+/** Return a random [Double] value between the given two limits (inclusive min, exclusive max). */
+fun random(min: Double, max: Double) = Math.random().let { min + (max - min) * it }
+
+/**
+ * Return this [Double] value if it lies between the two limits. If outside, return the
+ * minimum/maximum value correspondingly.
+ */
+fun Double.minmax(minVal: Double, maxVal: Double) = min(max(this, minVal), maxVal)
+
+/**
+ * Return this [Int] value if it lies between the two limits. If outside, return the
+ * minimum/maximum value correspondingly.
+ */
+fun Int.minmax(minVal: Int, maxVal: Int) = min(max(this, minVal), maxVal)
+
+fun nextPowerOf2(x: Int): Int {
+    return 1 shl (if (x == 0) 0 else 32 - Integer.numberOfLeadingZeros(x - 1))
+}