Scripting: Add Multi-Valued Field Methods to Expressions

Add methods to operate on multi-valued fields in the expressions language.
Note that users will still not be able to access individual values
within a multi-valued field.

The following methods will be included:

* min
* max
* avg
* median
* count
* sum

Additionally, changes have been made to MultiValueMode to support the
new median method.

closes #11105

docs/reference/search/request/sort.asciidoc

@@ -50,6 +50,8 @@ to. The `mode` option can have the following values:
         number based array fields.
 `avg`:: Use the average of all values as sort value. Only applicable
         for number based array fields.
+`median`:: Use the median of all values as sort value.  Only applicable
+           for number based array fields.
 
 ===== Sort mode example usage
 

src/main/java/org/elasticsearch/script/expression/CountMethodFunctionValues.java

@@ -0,0 +1,44 @@
+/*
+ * 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.script.expression;
+
+import org.apache.lucene.queries.function.ValueSource;
+import org.apache.lucene.queries.function.docvalues.DoubleDocValues;
+import org.elasticsearch.index.fielddata.AtomicNumericFieldData;
+import org.elasticsearch.index.fielddata.SortedNumericDoubleValues;
+
+/**
+ * FunctionValues to get the count of the number of values in a field for a document.
+ */
+public class CountMethodFunctionValues extends DoubleDocValues {
+    SortedNumericDoubleValues values;
+
+    CountMethodFunctionValues(ValueSource parent, AtomicNumericFieldData fieldData) {
+        super(parent);
+
+        values = fieldData.getDoubleValues();
+    }
+
+    @Override
+    public double doubleVal(int doc) {
+        values.setDocument(doc);
+        return values.count();
+    }
+}

src/main/java/org/elasticsearch/script/expression/CountMethodValueSource.java

@@ -0,0 +1,73 @@
+/*
+ * 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.script.expression;
+
+import org.apache.lucene.index.LeafReaderContext;
+import org.apache.lucene.queries.function.FunctionValues;
+import org.apache.lucene.queries.function.ValueSource;
+import org.elasticsearch.index.fielddata.AtomicFieldData;
+import org.elasticsearch.index.fielddata.AtomicNumericFieldData;
+import org.elasticsearch.index.fielddata.IndexFieldData;
+import org.elasticsearch.search.MultiValueMode;
+
+import java.io.IOException;
+import java.util.Map;
+import java.util.Objects;
+
+/**
+ * A ValueSource to create FunctionValues to get the count of the number of values in a field for a document.
+ */
+public class CountMethodValueSource extends ValueSource {
+    protected IndexFieldData<?> fieldData;
+
+    protected CountMethodValueSource(IndexFieldData<?> fieldData) {
+        Objects.requireNonNull(fieldData);
+
+        this.fieldData = fieldData;
+    }
+
+    @Override
+    public FunctionValues getValues(Map context, LeafReaderContext leaf) throws IOException {
+        AtomicFieldData leafData = fieldData.load(leaf);
+        assert(leafData instanceof AtomicNumericFieldData);
+
+        return new CountMethodFunctionValues(this, (AtomicNumericFieldData)leafData);
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        FieldDataValueSource that = (FieldDataValueSource) o;
+
+        return fieldData.equals(that.fieldData);
+    }
+
+    @Override
+    public int hashCode() {
+        return fieldData.hashCode();
+    }
+
+    @Override
+    public String description() {
+        return "count: field(" + fieldData.getFieldNames().toString() + ")";
+    }
+}

src/main/java/org/elasticsearch/script/expression/DateMethodFunctionValues.java

@@ -25,13 +25,14 @@
 
 import org.apache.lucene.queries.function.ValueSource;
 import org.elasticsearch.index.fielddata.AtomicNumericFieldData;
+import org.elasticsearch.search.MultiValueMode;
 
 class DateMethodFunctionValues extends FieldDataFunctionValues {
     private final int calendarType;
     private final Calendar calendar;
 
-    DateMethodFunctionValues(ValueSource parent, AtomicNumericFieldData data, int calendarType) {
-        super(parent, data);
+    DateMethodFunctionValues(ValueSource parent, MultiValueMode multiValueMode,  AtomicNumericFieldData data, int calendarType) {
+        super(parent, multiValueMode, data);
 
         this.calendarType = calendarType;
         calendar = Calendar.getInstance(TimeZone.getTimeZone("UTC"), Locale.ROOT);

src/main/java/org/elasticsearch/script/expression/DateMethodValueSource.java

@@ -29,21 +29,35 @@
 import org.elasticsearch.index.fielddata.AtomicFieldData;
 import org.elasticsearch.index.fielddata.AtomicNumericFieldData;
 import org.elasticsearch.index.fielddata.IndexFieldData;
+import org.elasticsearch.search.MultiValueMode;
 
 class DateMethodValueSource extends FieldDataValueSource {
 
     protected final String methodName;
     protected final int calendarType;
 
-    DateMethodValueSource(IndexFieldData<?> indexFieldData, String methodName, int calendarType) {
-        super(indexFieldData);
+    DateMethodValueSource(IndexFieldData<?> indexFieldData, MultiValueMode multiValueMode, String methodName, int calendarType) {
+        super(indexFieldData, multiValueMode);
 
         Objects.requireNonNull(methodName);
 
         this.methodName = methodName;
         this.calendarType = calendarType;
     }
 
+    @Override
+    public FunctionValues getValues(Map context, LeafReaderContext leaf) throws IOException {
+        AtomicFieldData leafData = fieldData.load(leaf);
+        assert(leafData instanceof AtomicNumericFieldData);
+
+        return new DateMethodFunctionValues(this, multiValueMode, (AtomicNumericFieldData)leafData, calendarType);
+    }
+
+    @Override
+    public String description() {
+        return methodName + ": field(" + fieldData.getFieldNames().toString() + ")";
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
@@ -64,17 +78,4 @@ public int hashCode() {
         result = 31 * result + calendarType;
         return result;
     }
-
-    @Override
-    public FunctionValues getValues(Map context, LeafReaderContext leaf) throws IOException {
-        AtomicFieldData leafData = fieldData.load(leaf);
-        assert(leafData instanceof AtomicNumericFieldData);
-
-        return new DateMethodFunctionValues(this, (AtomicNumericFieldData)leafData, calendarType);
-    }
-
-    @Override
-    public String description() {
-        return methodName + ": field(" + fieldData.getFieldNames().toString() + ")";
-    }
 }

src/main/java/org/elasticsearch/script/expression/ExpressionScriptEngineService.java

@@ -39,6 +39,7 @@
 import org.elasticsearch.script.ExecutableScript;
 import org.elasticsearch.script.ScriptEngineService;
 import org.elasticsearch.script.SearchScript;
+import org.elasticsearch.search.MultiValueMode;
 import org.elasticsearch.search.lookup.SearchLookup;
 
 import java.text.ParseException;
@@ -60,6 +61,13 @@ public class ExpressionScriptEngineService extends AbstractComponent implements
     protected static final String GET_MINUTES_METHOD      = "getMinutes";
     protected static final String GET_SECONDS_METHOD      = "getSeconds";
 
+    protected static final String MINIMUM_METHOD          = "min";
+    protected static final String MAXIMUM_METHOD          = "max";
+    protected static final String AVERAGE_METHOD          = "avg";
+    protected static final String MEDIAN_METHOD           = "median";
+    protected static final String SUM_METHOD              = "sum";
+    protected static final String COUNT_METHOD            = "count";
+
     @Inject
     public ExpressionScriptEngineService(Settings settings) {
         super(settings);
@@ -156,7 +164,7 @@ public SearchScript search(Object compiledScript, SearchLookup lookup, @Nullable
 
                 IndexFieldData<?> fieldData = lookup.doc().fieldDataService().getForField((NumberFieldMapper)field);
                 if (methodname == null) {
-                    bindings.add(variable, new FieldDataValueSource(fieldData));
+                    bindings.add(variable, new FieldDataValueSource(fieldData, MultiValueMode.MIN));
                 } else {
                     bindings.add(variable, getMethodValueSource(field, fieldData, fieldname, methodname));
                 }
@@ -180,6 +188,18 @@ protected ValueSource getMethodValueSource(FieldMapper<?> field, IndexFieldData<
                 return getDateMethodValueSource(field, fieldData, fieldName, methodName, Calendar.MINUTE);
             case GET_SECONDS_METHOD:
                 return getDateMethodValueSource(field, fieldData, fieldName, methodName, Calendar.SECOND);
+            case MINIMUM_METHOD:
+                return new FieldDataValueSource(fieldData, MultiValueMode.MIN);
+            case MAXIMUM_METHOD:
+                return new FieldDataValueSource(fieldData, MultiValueMode.MAX);
+            case AVERAGE_METHOD:
+                return new FieldDataValueSource(fieldData, MultiValueMode.AVG);
+            case MEDIAN_METHOD:
+                return new FieldDataValueSource(fieldData, MultiValueMode.MEDIAN);
+            case SUM_METHOD:
+                return new FieldDataValueSource(fieldData, MultiValueMode.SUM);
+            case COUNT_METHOD:
+                return new CountMethodValueSource(fieldData);
             default:
                 throw new IllegalArgumentException("Member method [" + methodName + "] does not exist.");
         }
@@ -190,7 +210,7 @@ protected ValueSource getDateMethodValueSource(FieldMapper<?> field, IndexFieldD
             throw new IllegalArgumentException("Member method [" + methodName + "] can only be used with a date field type, not the field [" + fieldName + "].");
         }
 
-        return new DateMethodValueSource(fieldData, methodName, calendarType);
+        return new DateMethodValueSource(fieldData, MultiValueMode.MIN, methodName, calendarType);
     }
 
     @Override

src/main/java/org/elasticsearch/script/expression/FieldDataFunctionValues.java

@@ -31,9 +31,9 @@
 class FieldDataFunctionValues extends DoubleDocValues {
     NumericDoubleValues dataAccessor;
 
-    FieldDataFunctionValues(ValueSource parent, AtomicNumericFieldData d) {
+    FieldDataFunctionValues(ValueSource parent, MultiValueMode m, AtomicNumericFieldData d) {
         super(parent);
-        dataAccessor = MultiValueMode.MIN.select(d.getDoubleValues(), 0d);
+        dataAccessor = m.select(d.getDoubleValues(), 0d);
     }
 
     @Override

src/main/java/org/elasticsearch/script/expression/FieldDataValueSource.java

@@ -25,6 +25,7 @@
 import org.elasticsearch.index.fielddata.AtomicFieldData;
 import org.elasticsearch.index.fielddata.AtomicNumericFieldData;
 import org.elasticsearch.index.fielddata.IndexFieldData;
+import org.elasticsearch.search.MultiValueMode;
 
 import java.io.IOException;
 import java.util.Map;
@@ -36,18 +37,14 @@
 class FieldDataValueSource extends ValueSource {
 
     protected IndexFieldData<?> fieldData;
+    protected MultiValueMode multiValueMode;
 
-    protected FieldDataValueSource(IndexFieldData<?> d) {
+    protected FieldDataValueSource(IndexFieldData<?> d, MultiValueMode m) {
         Objects.requireNonNull(d);
+        Objects.requireNonNull(m);
 
         fieldData = d;
-    }
-
-    @Override
-    public FunctionValues getValues(Map context, LeafReaderContext leaf) throws IOException {
-        AtomicFieldData leafData = fieldData.load(leaf);
-        assert(leafData instanceof AtomicNumericFieldData);
-        return new FieldDataFunctionValues(this, (AtomicNumericFieldData)leafData);
+        multiValueMode = m;
     }
 
     @Override
@@ -57,12 +54,23 @@ public boolean equals(Object o) {
 
         FieldDataValueSource that = (FieldDataValueSource) o;
 
-        return fieldData.equals(that.fieldData);
+        if (!fieldData.equals(that.fieldData)) return false;
+        return multiValueMode == that.multiValueMode;
+
     }
 
     @Override
     public int hashCode() {
-        return fieldData.hashCode();
+        int result = fieldData.hashCode();
+        result = 31 * result + multiValueMode.hashCode();
+        return result;
+    }
+
+    @Override
+    public FunctionValues getValues(Map context, LeafReaderContext leaf) throws IOException {
+        AtomicFieldData leafData = fieldData.load(leaf);
+        assert(leafData instanceof AtomicNumericFieldData);
+        return new FieldDataFunctionValues(this, multiValueMode, (AtomicNumericFieldData)leafData);
     }
 
     @Override