coreLib and Java collections utilities

core/util.runtime/src/org/jetbrains/jet/utils/coreLib.kt

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+/*
+ * Copyright 2010-2013 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.util
+
+fun Boolean.iif<T>(then: T, _else: T): T = if (this) then else _else
+
+// These two functions are needed in conjunction with iif:
+// foo.eq(bar).iif(a, b)
+fun <T> T.eq(eq: T): Boolean = this == eq
+fun <T> T.neq(eq: T): Boolean = this != eq

core/util.runtime/src/org/jetbrains/jet/utils/javaCollections.kt

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+package org.jetbrains.jet.utils
+
+import java.util.Collections
+
+public fun <T> emptyList(): MutableList<T> = Collections.emptyList<T>() as MutableList
+public fun <T: Any> emptyOrSingletonList(item: T?): MutableList<T> = if (item == null) emptyList() else Collections.singletonList(item) as MutableList
+
+public fun <T> emptySet(): MutableSet<T> = Collections.emptySet<T>() as MutableSet
+public fun <K, V> emptyMap(): MutableMap<K, V> = Collections.emptyMap<K, V>() as MutableMap
+