Query refactoring: Introduce toQuery() and fromXContent() in QueryBuilders and QueryParsers

The planed refactoring of search queries layed out in #9901 requires to split the "parse()"
method in QueryParsers into two methods, first a "fromXContent(...)" method that allows parsing
to an intermediate query representation (currently called FooQueryBuilder) and second a
"Query toQuery(...)" method on these intermediate representations that create the actual lucene queries.

This PR is a first step in that direction as it introduces the interface changes necessary for the further
refactoring. It introduces the new interface methods while for now keeping the old Builder/Parsers still
in place by delegating the new "toQuery()" implementations to the existing "parse()" methods, and by
introducing a "catch-all" "fromXContent()" implementation in a BaseQueryParser that returns a temporary
QueryBuilder wrapper implementation. This allows us to refactor the existing QueryBuilders step by step
while already beeing able to start refactoring queries with nested inner queries.

Closes #10580

Author: Christoph Büscher

src/main/java/org/elasticsearch/index/query/BaseQueryBuilder.java

@@ -19,6 +19,7 @@
 
 package org.elasticsearch.index.query;
 
+import org.apache.lucene.search.Query;
 import org.elasticsearch.ElasticsearchException;
 import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.xcontent.XContentBuilder;
@@ -68,5 +69,14 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
         return builder;
     }
 
+    public Query toQuery(QueryParseContext parseContext) throws QueryParsingException, IOException {
+        return parseContext.indexQueryParserService().queryParser(parserName()).parse(parseContext);
+    }
+
+    /**
+     * @return the name of the parser class the default toQuery() method delegates to
+     */
+    protected abstract String parserName();
+
     protected abstract void doXContent(XContentBuilder builder, Params params) throws IOException;
 }

src/main/java/org/elasticsearch/index/query/BaseQueryParser.java

@@ -0,0 +1,37 @@
+/*
+ * 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.index.query;
+
+import org.apache.lucene.search.Query;
+
+import java.io.IOException;
+
+/**
+ * Class used during the query parsers refactoring.
+ * All query parsers that have a refactored "fromXContent" method can be changed to extend this instead of {@link BaseQueryParserTemp}.
+ * Keeps old {@link QueryParser#parse(QueryParseContext)} method as a stub delegating to
+ * {@link QueryParser#fromXContent(QueryParseContext)} and {@link QueryBuilder#toQuery(QueryParseContext)}}
+ */
+public abstract class BaseQueryParser implements QueryParser {
+
+    public final Query parse(QueryParseContext parseContext) throws IOException, QueryParsingException {
+        return fromXContent(parseContext).toQuery(parseContext);
+    }
+}

src/main/java/org/elasticsearch/index/query/BaseQueryParserTemp.java

@@ -0,0 +1,37 @@
+/*
+ * 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.index.query;
+
+import org.apache.lucene.search.Query;
+
+import java.io.IOException;
+
+/**
+ * This class with method impl is an intermediate step in the refactoring.
+ * Method should be should be overwritten for all queries that already implement the toQuery/fromXContent split correctly.
+ * To be removed once all queries are refactored.
+ */
+public abstract class BaseQueryParserTemp implements QueryParser {
+
+    public QueryBuilder fromXContent(QueryParseContext parseContext) throws IOException, QueryParsingException {
+        Query query = parse(parseContext);
+        return new QueryWrappingQueryBuilder(query);
+    }
+}

src/main/java/org/elasticsearch/index/query/BoolQueryBuilder.java

@@ -42,7 +42,7 @@ public class BoolQueryBuilder extends BaseQueryBuilder implements BoostableQuery
     private Boolean disableCoord;
 
     private String minimumShouldMatch;
-    
+
     private Boolean adjustPureNegative;
 
     private String queryName;
@@ -126,7 +126,7 @@ public BoolQueryBuilder minimumShouldMatch(String minimumShouldMatch) {
     public boolean hasClauses() {
         return !(mustClauses.isEmpty() && shouldClauses.isEmpty() && mustNotClauses.isEmpty());
     }
-    
+
     /**
      * If a boolean query contains only negative ("must not") clauses should the
      * BooleanQuery be enhanced with a {@link MatchAllDocsQuery} in order to act
@@ -185,4 +185,7 @@ private void doXArrayContent(String field, List<QueryBuilder> clauses, XContentB
         }
     }
 
+    final protected String parserName() {
+        return BoolQueryParser.NAME;
+    }
 }

src/main/java/org/elasticsearch/index/query/BoolQueryParser.java

@@ -37,7 +37,7 @@
 /**
  *
  */
-public class BoolQueryParser implements QueryParser {
+public class BoolQueryParser extends BaseQueryParserTemp {
 
     public static final String NAME = "bool";
 
@@ -62,7 +62,7 @@ public Query parse(QueryParseContext parseContext) throws IOException, QueryPars
         List<BooleanClause> clauses = newArrayList();
         boolean adjustPureNegative = true;
         String queryName = null;
-        
+
         String currentFieldName = null;
         XContentParser.Token token;
         while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {

src/main/java/org/elasticsearch/index/query/BoostingQueryBuilder.java

@@ -95,4 +95,8 @@ protected void doXContent(XContentBuilder builder, Params params) throws IOExcep
         }
         builder.endObject();
     }
+
+    final protected String parserName() {
+        return BoostingQueryParser.NAME;
+    }
 }

src/main/java/org/elasticsearch/index/query/BoostingQueryParser.java

@@ -29,7 +29,7 @@
 /**
  *
  */
-public class BoostingQueryParser implements QueryParser {
+public class BoostingQueryParser extends BaseQueryParserTemp {
 
     public static final String NAME = "boosting";
 

src/main/java/org/elasticsearch/index/query/CommonTermsQueryBuilder.java

@@ -19,6 +19,9 @@
 
 package org.elasticsearch.index.query;
 
+import org.apache.lucene.index.Term;
+import org.apache.lucene.search.BooleanQuery;
+import org.apache.lucene.search.similarities.Similarity;
 import org.elasticsearch.ElasticsearchIllegalArgumentException;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
@@ -198,4 +201,8 @@ public void doXContent(XContentBuilder builder, Params params) throws IOExceptio
         builder.endObject();
         builder.endObject();
     }
+
+    final protected String parserName() {
+        return CommonTermsQueryParser.NAME;
+    }
 }

src/main/java/org/elasticsearch/index/query/CommonTermsQueryParser.java

@@ -39,7 +39,7 @@
 /**
  *
  */
-public class CommonTermsQueryParser implements QueryParser {
+public class CommonTermsQueryParser extends BaseQueryParserTemp {
 
     public static final String NAME = "common";
 

src/main/java/org/elasticsearch/index/query/ConstantScoreQueryBuilder.java

@@ -19,6 +19,7 @@
 
 package org.elasticsearch.index.query;
 
+import org.apache.lucene.search.Query;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
@@ -35,7 +36,7 @@ public class ConstantScoreQueryBuilder extends BaseQueryBuilder implements Boost
     private final QueryBuilder queryBuilder;
 
     private float boost = -1;
-    
+
 
     /**
      * A query that wraps a filter and simply returns a constant score equal to the
@@ -56,7 +57,7 @@ public ConstantScoreQueryBuilder(FilterBuilder filterBuilder) {
     public ConstantScoreQueryBuilder(QueryBuilder queryBuilder) {
         this.filterBuilder = null;
         this.queryBuilder = queryBuilder;
-    }    
+    }
 
     /**
      * Sets the boost for this query.  Documents matching this query will (in addition to the normal
@@ -77,12 +78,16 @@ protected void doXContent(XContentBuilder builder, Params params) throws IOExcep
             queryBuilder.toXContent(builder, params);
         } else {
             builder.field("filter");
-            filterBuilder.toXContent(builder, params);  
+            filterBuilder.toXContent(builder, params);
         }
-        
+
         if (boost != -1) {
             builder.field("boost", boost);
         }
         builder.endObject();
     }
-}
+
+    final protected String parserName() {
+        return ConstantScoreQueryParser.NAME;
+    }
+}