json format for TreeNode

sql/catalyst/pom.xml

@@ -103,6 +103,22 @@
           </execution>
         </executions>
       </plugin>
+      <plugin>
+        <groupId>com.thoughtworks.paranamer</groupId>
+        <artifactId>paranamer-maven-plugin</artifactId>
+        <executions>
+          <execution>
+            <id>run</id>  <!-- id is optional -->
+            <configuration>
+              <sourceDirectory>${project.build.sourceDirectory}</sourceDirectory>
+              <outputDirectory>${project.build.outputDirectory}</outputDirectory>
+            </configuration>
+            <goals>
+              <goal>generate</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
     </plugins>
   </build>
   <profiles>

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/JavaTypeInference.scala

@@ -21,6 +21,8 @@ import java.beans.{PropertyDescriptor, Introspector}
 import java.lang.{Iterable => JIterable}
 import java.util.{Iterator => JIterator, Map => JMap, List => JList}
 
+import com.thoughtworks.paranamer.{BytecodeReadingParanamer, CachingParanamer, Paranamer}
+
 import scala.language.existentials
 
 import com.google.common.reflect.TypeToken
@@ -405,4 +407,11 @@ object JavaTypeInference {
       }
     }
   }
+
+  private val paranamer: Paranamer = new BytecodeReadingParanamer()
+
+  def getConstructorParaNames(cls: Class[_]): Seq[String] = {
+    val ctr = cls.getConstructors.maxBy(_.getParameterCount)
+    paranamer.lookupParameterNames(ctr)
+  }
 }

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/namedExpressions.scala

@@ -262,6 +262,10 @@ case class AttributeReference(
     }
   }
 
+  override protected final def otherCopyArgs: Seq[AnyRef] = {
+    exprId :: qualifiers :: Nil
+  }
+
   override def toString: String = s"$name#${exprId.id}$typeSuffix"
 
   // Since the expression id is not in the first constructor it is missing from the default

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/trees/TreeNode.scala

@@ -17,7 +17,12 @@
 
 package org.apache.spark.sql.catalyst.trees
 
+import org.apache.spark.sql.catalyst.JavaTypeInference
+
 import scala.collection.Map
+import org.json4s.JsonAST._
+import org.json4s.JsonDSL._
+import org.json4s.jackson.JsonMethods._
 
 import org.apache.spark.sql.catalyst.errors._
 import org.apache.spark.sql.types.{StructType, DataType}
@@ -463,4 +468,40 @@ abstract class TreeNode[BaseType <: TreeNode[BaseType]] extends Product {
     }
     s"$nodeName(${args.mkString(",")})"
   }
+
+  private[sql] def jsonValue: JValue = {
+    val fieldNames = JavaTypeInference.getConstructorParaNames(getClass)
+    val fieldValues = productIterator.toSeq ++ otherCopyArgs
+    assert(fieldNames.length == fieldValues.length, s"${getClass.getSimpleName} fields: " +
+      fieldNames.mkString(", ") + s", values: " + fieldValues.map(_.toString).mkString(", "))
+
+    val jsonFields: Seq[JField] = fieldNames.zip(fieldValues).flatMap {
+      case (name, value: TreeNode[_]) if containsChild(value) => None
+      case (name, value: TreeNode[_]) => Some(name -> value.allJsonValues)
+      case (name, value: Seq[BaseType]) if value.toSet.subsetOf(children.toSet) => None
+      case (name, value: Seq[_]) =>
+        if (value.length > 0 && value(0).isInstanceOf[TreeNode[_]]) {
+          Some(name -> JArray(value.map(_.asInstanceOf[TreeNode[_]].allJsonValues).toList))
+        } else {
+          Some(name -> JArray(value.map(v => JString(v.toString)).toList))
+        }
+      case (name, value: Set[_]) =>
+        Some(name -> JArray(value.map(v => JString(v.toString)).toList))
+      case (name, value) => Some(name -> JString(value.toString))
+    }
+
+    JObject(("node-name" -> JString(nodeName)) :: jsonFields.toList)
+  }
+
+  private def allJsonValues: JValue = {
+    val jsonValues = scala.collection.mutable.ArrayBuffer.empty[JValue]
+    def collectJsonValue(node: BaseType): Unit = {
+      jsonValues += node.jsonValue.merge(JObject("num-children" -> JInt(node.children.length)))
+      node.children.foreach(collectJsonValue)
+    }
+    collectJsonValue(this)
+    jsonValues
+  }
+
+  def toJSON: String = pretty(render(allJsonValues))
 }

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/util/TreeNodeJsonFormatSuite.scala

@@ -0,0 +1,30 @@
+/*
+* Licensed to the Apache Software Foundation (ASF) under one or more
+* contributor license agreements.  See the NOTICE file distributed with
+* this work for additional information regarding copyright ownership.
+* The ASF 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.apache.spark.sql.catalyst.util
+
+import org.apache.spark.SparkFunSuite
+import org.apache.spark.sql.catalyst.dsl.plans._
+import org.apache.spark.sql.catalyst.dsl.expressions._
+
+class TreeNodeJsonFormatSuite extends SparkFunSuite {
+  import org.apache.spark.sql.catalyst.analysis.TestRelations._
+
+  test("logical plan json format") {
+    println(testRelation.select(('a + 1).as("i"), ('a * 2).as("j")).sortBy('i.asc).toJSON)
+  }
+}