org.jetbrains.kotlin.utils.addToStdlib.kt Maven / Gradle / Ivy
/*
* Copyright 2010-2015 JetBrains s.r.o.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.jetbrains.kotlin.utils.addToStdlib
import java.lang.reflect.Modifier
import java.util.*
import java.util.concurrent.ConcurrentHashMap
fun T?.singletonOrEmptyList(): List = if (this != null) Collections.singletonList(this) else Collections.emptyList()
fun T.singletonList(): List = Collections.singletonList(this)
fun T?.singletonOrEmptySet(): Set = if (this != null) Collections.singleton(this) else Collections.emptySet()
inline fun Sequence<*>.firstIsInstanceOrNull(): T? {
for (element in this) if (element is T) return element
return null
}
inline fun Iterable<*>.firstIsInstanceOrNull(): T? {
for (element in this) if (element is T) return element
return null
}
inline fun Array<*>.firstIsInstanceOrNull(): T? {
for (element in this) if (element is T) return element
return null
}
inline fun Sequence<*>.firstIsInstance(): T {
for (element in this) if (element is T) return element
throw NoSuchElementException("No element of given type found")
}
inline fun Iterable<*>.firstIsInstance(): T {
for (element in this) if (element is T) return element
throw NoSuchElementException("No element of given type found")
}
inline fun Array<*>.firstIsInstance(): T {
for (element in this) if (element is T) return element
throw NoSuchElementException("No element of given type found")
}
inline fun Iterable<*>.lastIsInstanceOrNull(): T? {
when (this) {
is List<*> -> {
for (i in this.indices.reversed()) {
val element = this[i]
if (element is T) return element
}
return null
}
else -> {
return reversed().firstIsInstanceOrNull()
}
}
}
fun sequenceOfLazyValues(vararg elements: () -> T): Sequence = elements.asSequence().map { it() }
fun Pair.swap(): Pair = Pair(second, first)
fun T.check(predicate: (T) -> Boolean): T? = if (predicate(this)) this else null
fun constant(calculator: () -> T): T {
val cached = constantMap[calculator]
@Suppress("UNCHECKED_CAST")
if (cached != null) return cached as T
// safety check
val fields = calculator.javaClass.declaredFields.filter { it.modifiers.and(Modifier.STATIC) == 0 }
assert(fields.isEmpty()) {
"No fields in the passed lambda expected but ${fields.joinToString()} found"
}
val value = calculator()
constantMap[calculator] = value
return value
}
private val constantMap = ConcurrentHashMap, Any>()
fun String.indexOfOrNull(char: Char, startIndex: Int = 0, ignoreCase: Boolean = false): Int? {
val index = indexOf(char, startIndex, ignoreCase)
return if (index >= 0) index else null
}
fun String.lastIndexOfOrNull(char: Char, startIndex: Int = 0, ignoreCase: Boolean = false): Int? {
val index = lastIndexOf(char, startIndex, ignoreCase)
return if (index >= 0) index else null
}
inline fun Iterable.firstNotNullResult(transform: (T) -> R?): R? {
for (element in this) {
val result = transform(element)
if (result != null) return result
}
return null
}
inline fun Iterable.sumByLong(selector: (T) -> Long): Long {
var sum: Long = 0
for (element in this) {
sum += selector(element)
}
return sum
}
inline fun , O> C.ifNotEmpty(body: C.() -> O?): O? = if (isNotEmpty()) this.body() else null
inline fun Array.ifNotEmpty(body: Array.() -> O?): O? = if (isNotEmpty()) this.body() else null