Add parsing for single bucket aggregations (#24564)

This adds parsing to all implementations of SingleBucketAggregations. They are mostly similar, so they share the common
base class `ParsedSingleBucketAggregation` and the shared base test `InternalSingleBucketAggregationTestCase`.

Author: cbuescher

core/src/main/java/org/elasticsearch/search/aggregations/ParsedAggregation.java

@@ -41,7 +41,7 @@ protected static void declareAggregationFields(ObjectParser<? extends ParsedAggr
     }
 
     private String name;
-    Map<String, Object> metadata;
+    protected Map<String, Object> metadata;
 
     @Override
     public final String getName() {

core/src/main/java/org/elasticsearch/search/aggregations/bucket/ParsedSingleBucketAggregation.java

@@ -0,0 +1,93 @@
+/*
+ * 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.search.aggregations.bucket;
+
+import org.elasticsearch.common.xcontent.XContentBuilder;
+import org.elasticsearch.common.xcontent.XContentParser;
+import org.elasticsearch.common.xcontent.XContentParserUtils;
+import org.elasticsearch.search.aggregations.Aggregation;
+import org.elasticsearch.search.aggregations.Aggregations;
+import org.elasticsearch.search.aggregations.ParsedAggregation;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import static org.elasticsearch.common.xcontent.XContentParserUtils.ensureExpectedToken;
+
+/**
+ * A base class for all the single bucket aggregations.
+ */
+public abstract class ParsedSingleBucketAggregation extends ParsedAggregation implements SingleBucketAggregation {
+
+    private long docCount;
+    protected Aggregations aggregations = new Aggregations(Collections.emptyList());
+
+    @Override
+    public long getDocCount() {
+        return docCount;
+    }
+
+    protected void setDocCount(long docCount) {
+        this.docCount = docCount;
+    }
+
+    @Override
+    public Aggregations getAggregations() {
+        return aggregations;
+    }
+
+    @Override
+    public XContentBuilder doXContentBody(XContentBuilder builder, Params params) throws IOException {
+        builder.field(CommonFields.DOC_COUNT.getPreferredName(), docCount);
+        aggregations.toXContentInternal(builder, params);
+        return builder;
+    }
+
+    protected static <T extends ParsedSingleBucketAggregation> T parseXContent(final XContentParser parser, T aggregation, String name)
+            throws IOException {
+        aggregation.setName(name);
+        XContentParser.Token token = parser.currentToken();
+        String currentFieldName = parser.currentName();
+        if (token == XContentParser.Token.FIELD_NAME) {
+            token = parser.nextToken();
+        }
+        ensureExpectedToken(XContentParser.Token.START_OBJECT, token, parser::getTokenLocation);
+
+        List<Aggregation> aggregations = new ArrayList<>();
+        while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
+            if (token == XContentParser.Token.FIELD_NAME) {
+                currentFieldName = parser.currentName();
+            } else if (token.isValue()) {
+                if (CommonFields.DOC_COUNT.getPreferredName().equals(currentFieldName)) {
+                    aggregation.setDocCount(parser.longValue());
+                }
+            } else if (token == XContentParser.Token.START_OBJECT) {
+                if (CommonFields.META.getPreferredName().equals(currentFieldName)) {
+                    aggregation.metadata = parser.map();
+                } else {
+                    aggregations.add(XContentParserUtils.parseTypedKeysObject(parser, Aggregation.TYPED_KEYS_DELIMITER, Aggregation.class));
+                }
+            }
+        }
+        aggregation.aggregations = new Aggregations(aggregations);
+        return aggregation;
+    }
+}

core/src/main/java/org/elasticsearch/search/aggregations/bucket/children/ParsedChildren.java

@@ -0,0 +1,36 @@
+/*
+ * 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.search.aggregations.bucket.children;
+
+import org.elasticsearch.common.xcontent.XContentParser;
+import org.elasticsearch.search.aggregations.bucket.ParsedSingleBucketAggregation;
+
+import java.io.IOException;
+
+public class ParsedChildren extends ParsedSingleBucketAggregation implements Children {
+
+    @Override
+    public String getType() {
+        return ChildrenAggregationBuilder.NAME;
+    }
+
+    public static ParsedChildren fromXContent(XContentParser parser, final String name) throws IOException {
+        return parseXContent(parser, new ParsedChildren(), name);
+    }
+}

core/src/main/java/org/elasticsearch/search/aggregations/bucket/filter/ParsedFilter.java

@@ -0,0 +1,36 @@
+/*
+ * 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.search.aggregations.bucket.filter;
+
+import org.elasticsearch.common.xcontent.XContentParser;
+import org.elasticsearch.search.aggregations.bucket.ParsedSingleBucketAggregation;
+
+import java.io.IOException;
+
+public class ParsedFilter extends ParsedSingleBucketAggregation implements Filter {
+
+    @Override
+    public String getType() {
+        return FilterAggregationBuilder.NAME;
+    }
+
+    public static ParsedFilter fromXContent(XContentParser parser, final String name) throws IOException {
+        return parseXContent(parser, new ParsedFilter(), name);
+    }
+}

core/src/main/java/org/elasticsearch/search/aggregations/bucket/global/ParsedGlobal.java

@@ -0,0 +1,36 @@
+/*
+ * 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.search.aggregations.bucket.global;
+
+import org.elasticsearch.common.xcontent.XContentParser;
+import org.elasticsearch.search.aggregations.bucket.ParsedSingleBucketAggregation;
+
+import java.io.IOException;
+
+public class ParsedGlobal extends ParsedSingleBucketAggregation implements Global {
+
+    @Override
+    public String getType() {
+        return GlobalAggregationBuilder.NAME;
+    }
+
+    public static ParsedGlobal fromXContent(XContentParser parser, final String name) throws IOException {
+        return parseXContent(parser, new ParsedGlobal(), name);
+    }
+}

core/src/main/java/org/elasticsearch/search/aggregations/bucket/missing/ParsedMissing.java

@@ -0,0 +1,36 @@
+/*
+ * 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.search.aggregations.bucket.missing;
+
+import org.elasticsearch.common.xcontent.XContentParser;
+import org.elasticsearch.search.aggregations.bucket.ParsedSingleBucketAggregation;
+
+import java.io.IOException;
+
+public class ParsedMissing extends ParsedSingleBucketAggregation implements Missing {
+
+    @Override
+    public String getType() {
+        return MissingAggregationBuilder.NAME;
+    }
+
+    public static ParsedMissing fromXContent(XContentParser parser, final String name) throws IOException {
+        return parseXContent(parser, new ParsedMissing(), name);
+    }
+}

core/src/main/java/org/elasticsearch/search/aggregations/bucket/nested/ParsedNested.java

@@ -0,0 +1,36 @@
+/*
+ * 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.search.aggregations.bucket.nested;
+
+import org.elasticsearch.common.xcontent.XContentParser;
+import org.elasticsearch.search.aggregations.bucket.ParsedSingleBucketAggregation;
+
+import java.io.IOException;
+
+public class ParsedNested extends ParsedSingleBucketAggregation implements Nested {
+
+    @Override
+    public String getType() {
+        return NestedAggregationBuilder.NAME;
+    }
+
+    public static ParsedNested fromXContent(XContentParser parser, final String name) throws IOException {
+        return parseXContent(parser, new ParsedNested(), name);
+    }
+}

core/src/main/java/org/elasticsearch/search/aggregations/bucket/nested/ParsedReverseNested.java

@@ -0,0 +1,36 @@
+/*
+ * 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.search.aggregations.bucket.nested;
+
+import org.elasticsearch.common.xcontent.XContentParser;
+import org.elasticsearch.search.aggregations.bucket.ParsedSingleBucketAggregation;
+
+import java.io.IOException;
+
+public class ParsedReverseNested extends ParsedSingleBucketAggregation implements Nested {
+
+    @Override
+    public String getType() {
+        return ReverseNestedAggregationBuilder.NAME;
+    }
+
+    public static ParsedReverseNested fromXContent(XContentParser parser, final String name) throws IOException {
+        return parseXContent(parser, new ParsedReverseNested(), name);
+    }
+}

core/src/main/java/org/elasticsearch/search/aggregations/bucket/sampler/InternalSampler.java

@@ -49,7 +49,7 @@ public String getWriteableName() {
 
     @Override
     public String getType() {
-        return "sampler";
+        return NAME;
     }
 
     @Override

core/src/main/java/org/elasticsearch/search/aggregations/bucket/sampler/ParsedSampler.java

@@ -0,0 +1,36 @@
+/*
+ * 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.search.aggregations.bucket.sampler;
+
+import org.elasticsearch.common.xcontent.XContentParser;
+import org.elasticsearch.search.aggregations.bucket.ParsedSingleBucketAggregation;
+
+import java.io.IOException;
+
+public class ParsedSampler extends ParsedSingleBucketAggregation implements Sampler {
+
+    @Override
+    public String getType() {
+        return InternalSampler.NAME;
+    }
+
+    public static ParsedSampler fromXContent(XContentParser parser, final String name) throws IOException {
+        return parseXContent(parser, new ParsedSampler(), name);
+    }
+}