Json support in painless

docs/painless/painless-api-reference/painless-api-reference-shared/index.asciidoc

@@ -420,6 +420,7 @@ The following classes are available grouped by their respective packages. Click
 <<painless-api-reference-shared-org-elasticsearch-painless-api, Expand details for org.elasticsearch.painless.api>>
 
 * <<painless-api-reference-shared-Debug, Debug>>
+* <<painless-api-reference-shared-Json, Json>>
 
 ==== org.elasticsearch.script
 <<painless-api-reference-shared-org-elasticsearch-script, Expand details for org.elasticsearch.script>>

docs/painless/painless-api-reference/painless-api-reference-shared/packages.asciidoc

@@ -8509,6 +8509,12 @@ See the <<painless-api-reference-shared, Shared API>> for a high-level overview
 === Shared API for package org.elasticsearch.script
 See the <<painless-api-reference-shared, Shared API>> for a high-level overview of all packages and classes.
 
+[[painless-api-reference-shared-Json]]
+==== Json
+*  static def load(String)
+*  static String dump(Object)
+*  static String dump(Object, boolean)
+
 [[painless-api-reference-shared-JodaCompatibleZonedDateTime]]
 ==== JodaCompatibleZonedDateTime
 * int {java11-javadoc}/java.base/java/time/chrono/ChronoZonedDateTime.html#compareTo(java.time.chrono.ChronoZonedDateTime)[compareTo](ChronoZonedDateTime)

modules/lang-painless/src/main/java/org/elasticsearch/painless/api/Json.java

@@ -0,0 +1,66 @@
+/*
+ * 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.painless.api;
+
+import org.elasticsearch.common.xcontent.DeprecationHandler;
+import org.elasticsearch.common.xcontent.NamedXContentRegistry;
+import org.elasticsearch.common.xcontent.XContentBuilder;
+import org.elasticsearch.common.xcontent.XContentParser;
+import org.elasticsearch.common.xcontent.json.JsonXContent;
+
+import java.io.IOException;
+
+public class Json {
+    public static Object load(String json) throws IOException{
+        XContentParser parser = JsonXContent.jsonXContent.createParser(
+            NamedXContentRegistry.EMPTY,
+            DeprecationHandler.THROW_UNSUPPORTED_OPERATION,
+            json);
+
+        switch (parser.nextToken()) {
+            case START_ARRAY:
+                return parser.list();
+            case START_OBJECT:
+                return parser.map();
+            case VALUE_NUMBER:
+                return parser.numberValue();
+            case VALUE_BOOLEAN:
+                return parser.booleanValue();
+            case VALUE_STRING:
+                return parser.text();
+            default:
+                return null;
+        }
+    }
+
+    public static String dump(Object data) throws IOException {
+      return dump(data, false);
+    }
+
+    public static String dump(Object data, boolean pretty) throws IOException {
+        XContentBuilder builder = JsonXContent.contentBuilder();
+        if (pretty) {
+            builder.prettyPrint();
+        }
+        builder.value(data);
+        builder.flush();
+        return builder.getOutputStream().toString();
+    }
+}

modules/lang-painless/src/main/resources/org/elasticsearch/painless/spi/org.elasticsearch.txt

@@ -57,6 +57,14 @@ class org.elasticsearch.painless.api.Debug {
   void explain(Object)
 }
 
+#### Painless Json API
+
+class org.elasticsearch.painless.api.Json {
+  def load(String)
+  String dump(Object)
+  String dump(Object, boolean)
+}
+
 #### ES Scripting API
 
 class org.elasticsearch.common.geo.GeoPoint {

modules/lang-painless/src/test/java/org/elasticsearch/painless/JsonTests.java

@@ -0,0 +1,49 @@
+/*
+ * 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.painless;
+
+import static java.util.Collections.singletonList;
+import static java.util.Collections.singletonMap;
+
+public class JsonTests extends ScriptTestCase {
+    public void testDump() {
+        // simple object dump
+        Object output = exec("Json.dump(params.data)", singletonMap("data", singletonMap("hello", "world")), true);
+        assertEquals("{\"hello\":\"world\"}", output);
+
+        output = exec("Json.dump(params.data)", singletonMap("data", singletonList(42)), true);
+        assertEquals("[42]", output);
+
+        // pretty print
+        output = exec("Json.dump(params.data, true)", singletonMap("data", singletonMap("hello", "world")), true);
+        assertEquals("{\n  \"hello\" : \"world\"\n}", output);
+    }
+
+    public void testLoad() {
+        String json = "{\"hello\":\"world\"}";
+        Object output = exec("Json.load(params.json)", singletonMap("json", json), true);
+        assertEquals(singletonMap("hello", "world"), output);
+
+        json = "[42]";
+        output = exec("Json.load(params.json)", singletonMap("json", json), true);
+        assertEquals(singletonList(42), output);
+    }
+
+}