8187443: Forest Consolidation: Move files to unified layout

Reviewed-by: darcy, ihse

src/java.base/share/classes/java/util/function/Function.java

@@ -0,0 +1,100 @@
+/*
+ * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package java.util.function;
+
+import java.util.Objects;
+
+/**
+ * Represents a function that accepts one argument and produces a result.
+ *
+ * <p>This is a <a href="package-summary.html">functional interface</a>
+ * whose functional method is {@link #apply(Object)}.
+ *
+ * @param <T> the type of the input to the function
+ * @param <R> the type of the result of the function
+ *
+ * @since 1.8
+ */
+@FunctionalInterface
+public interface Function<T, R> {
+
+    /**
+     * Applies this function to the given argument.
+     *
+     * @param t the function argument
+     * @return the function result
+     */
+    R apply(T t);
+
+    /**
+     * Returns a composed function that first applies the {@code before}
+     * function to its input, and then applies this function to the result.
+     * If evaluation of either function throws an exception, it is relayed to
+     * the caller of the composed function.
+     *
+     * @param <V> the type of input to the {@code before} function, and to the
+     *           composed function
+     * @param before the function to apply before this function is applied
+     * @return a composed function that first applies the {@code before}
+     * function and then applies this function
+     * @throws NullPointerException if before is null
+     *
+     * @see #andThen(Function)
+     */
+    default <V> Function<V, R> compose(Function<? super V, ? extends T> before) {
+        Objects.requireNonNull(before);
+        return (V v) -> apply(before.apply(v));
+    }
+
+    /**
+     * Returns a composed function that first applies this function to
+     * its input, and then applies the {@code after} function to the result.
+     * If evaluation of either function throws an exception, it is relayed to
+     * the caller of the composed function.
+     *
+     * @param <V> the type of output of the {@code after} function, and of the
+     *           composed function
+     * @param after the function to apply after this function is applied
+     * @return a composed function that first applies this function and then
+     * applies the {@code after} function
+     * @throws NullPointerException if after is null
+     *
+     * @see #compose(Function)
+     */
+    default <V> Function<T, V> andThen(Function<? super R, ? extends V> after) {
+        Objects.requireNonNull(after);
+        return (T t) -> after.apply(apply(t));
+    }
+
+    /**
+     * Returns a function that always returns its input argument.
+     *
+     * @param <T> the type of the input and output objects to the function
+     * @return a function that always returns its input argument
+     */
+    static <T> Function<T, T> identity() {
+        return t -> t;
+    }
+}