Introduced whileSelect convenience function

Author: elizarov

kotlinx-coroutines-core/src/main/kotlin/kotlinx/coroutines/experimental/selects/WhileSelect.kt

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2016-2017 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 kotlinx.coroutines.experimental.selects
+
+/**
+ * Loops while [select] expression returns `true`.
+ *
+ * The statement of the form:
+ *
+ * ```
+ * whileSelect {
+ *     /*body*/
+ * }
+ * ```
+ *
+ * is a shortcut for:
+ *
+ * ```
+ * while(select<Boolean> {
+ *    /*body*/
+ * }) {}
+ */
+suspend fun whileSelect(builder: SelectBuilder<Boolean>.() -> Unit) {
+    while(select<Boolean>(builder)) {}
+}