Query DSL: `match_all` filter, closes #365.

modules/elasticsearch/src/main/java/org/elasticsearch/index/query/xcontent/FilterBuilders.java

@@ -26,6 +26,13 @@ package org.elasticsearch.index.query.xcontent;
  */
 public abstract class FilterBuilders {
 
+    /**
+     * A filter that matches all documents.
+     */
+    public static MatchAllFilterBuilder matchAllFilter() {
+        return new MatchAllFilterBuilder();
+    }
+
     /**
      * A filter for a field based on a term.
      *

modules/elasticsearch/src/main/java/org/elasticsearch/index/query/xcontent/MatchAllFilterBuilder.java

@@ -0,0 +1,42 @@
+/*
+ * Licensed to Elastic Search and Shay Banon under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. Elastic Search 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.index.query.xcontent;
+
+import org.elasticsearch.common.xcontent.builder.XContentBuilder;
+
+import java.io.IOException;
+
+/**
+ * A filter that simply wraps a query.
+ *
+ * @author kimchy (shay.banon)
+ */
+public class MatchAllFilterBuilder extends BaseFilterBuilder {
+
+    /**
+     * A filter that simply matches all docs.
+     */
+    public MatchAllFilterBuilder() {
+    }
+
+    @Override protected void doXContent(XContentBuilder builder, Params params) throws IOException {
+        builder.startObject(MatchAllFilterParser.NAME).endObject();
+    }
+}

modules/elasticsearch/src/main/java/org/elasticsearch/index/query/xcontent/MatchAllFilterParser.java

@@ -0,0 +1,59 @@
+/*
+ * Licensed to Elastic Search and Shay Banon under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. Elastic Search 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.index.query.xcontent;
+
+import org.apache.lucene.search.Filter;
+import org.elasticsearch.common.Strings;
+import org.elasticsearch.common.inject.Inject;
+import org.elasticsearch.common.lucene.search.Queries;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.xcontent.XContentParser;
+import org.elasticsearch.index.AbstractIndexComponent;
+import org.elasticsearch.index.Index;
+import org.elasticsearch.index.query.QueryParsingException;
+import org.elasticsearch.index.settings.IndexSettings;
+
+import java.io.IOException;
+
+/**
+ * @author kimchy (shay.banon)
+ */
+public class MatchAllFilterParser extends AbstractIndexComponent implements XContentFilterParser {
+
+    public static final String NAME = "match_all";
+
+    @Inject public MatchAllFilterParser(Index index, @IndexSettings Settings settings) {
+        super(index, settings);
+    }
+
+    @Override public String[] names() {
+        return new String[]{NAME, Strings.toCamelCase(NAME)};
+    }
+
+    @Override public Filter parse(QueryParseContext parseContext) throws IOException, QueryParsingException {
+        XContentParser parser = parseContext.parser();
+
+        XContentParser.Token token;
+        while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
+        }
+
+        return Queries.MATCH_ALL_FILTER;
+    }
+}

modules/elasticsearch/src/main/java/org/elasticsearch/index/query/xcontent/XContentQueryParserRegistry.java

@@ -95,6 +95,7 @@ public class XContentQueryParserRegistry {
         add(filterParsersMap, new AndFilterParser(index, indexSettings));
         add(filterParsersMap, new OrFilterParser(index, indexSettings));
         add(filterParsersMap, new NotFilterParser(index, indexSettings));
+        add(filterParsersMap, new MatchAllFilterParser(index, indexSettings));
 
         if (filterParsers != null) {
             for (XContentFilterParser filterParser : filterParsers) {