Date: Add DateFormatters class that uses java.time

server/src/main/java/org/elasticsearch/common/time/DateFormatter.java

@@ -0,0 +1,76 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you 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.elasticsearch.common.time;
+
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
+import java.time.format.DateTimeParseException;
+import java.time.temporal.TemporalAccessor;
+import java.util.Arrays;
+import java.util.stream.Stream;
+
+/**
+ * wrapper class around java.time.DateTimeFormatter that supports multiple formats for easier parsing
+ */
+public class DateFormatter {
+
+    private DateTimeFormatter printer;
+    private DateTimeFormatter[] parsers;
+
+    public DateFormatter(DateTimeFormatter printer, DateTimeFormatter ... parsers) {
+        this.printer = printer;
+        this.parsers = parsers;
+    }
+
+    public TemporalAccessor parse(String input) {
+        if (parsers.length > 0) {
+            for (int i = 0; i < parsers.length; i++) {
+                try {
+                    return parsers[i].parse(input);
+                } catch (DateTimeParseException e) {}
+            }
+        }
+
+        return printer.parse(input);
+    }
+
+    public DateFormatter withZone(ZoneId zoneId) {
+        printer = printer.withZone(zoneId);
+        for (int i = 0; i < parsers.length; i++) {
+            parsers[i] = parsers[i].withZone(zoneId);
+        }
+
+        return this;
+    }
+
+    public String format(TemporalAccessor accessor) {
+        return printer.format(accessor);
+    }
+
+    // for internal use only
+    private DateTimeFormatter[] all() {
+        return Stream.concat(Arrays.stream(new DateTimeFormatter[] { printer }), Arrays.stream(parsers)).toArray(DateTimeFormatter[]::new);
+    }
+
+    public static DateFormatter merge(DateFormatter ... dateFormatters) {
+        DateTimeFormatter[] parsers = Arrays.stream(dateFormatters).map(DateFormatter::all)
+            .flatMap(Arrays::stream).toArray(DateTimeFormatter[]::new);
+        return new DateFormatter(dateFormatters[0].printer, parsers);
+    }
+}