[SPARK-7886] Add built-in expressions to FunctionRegistry.

This patch switches to using FunctionRegistry for built-in expressions. It is based on #6463, but with some work to simplify it along with unit tests.

TODOs for future pull requests:
- Use static registration so we don't need to register all functions every time we start a new SQLContext
- Switch to using this in HiveContext

Author: Reynold Xin <rxin@databricks.com>
Author: Santiago M. Mola <santi@mola.io>

Closes #6710 from rxin/udf-registry and squashes the following commits:

6930822 [Reynold Xin] Fixed Python test.
b802c9a [Reynold Xin] Made UDF case insensitive.
e60d815 [Reynold Xin] Made UDF case insensitive.
852f9c0 [Reynold Xin] Fixed style violation.
e76a3c1 [Reynold Xin] Fixed parser.
52ddaba [Reynold Xin] Fixed compilation.
ee7854f [Reynold Xin] Improved error reporting.
ff906f2 [Reynold Xin] More robust constructor calling.
77b46f1 [Reynold Xin] Simplified the code.
2a2a149 [Reynold Xin] Merge pull request #6463 from smola/SPARK-7886
8616924 [Santiago M. Mola] [SPARK-7886] Add built-in expressions to FunctionRegistry.

2 files changed, 9 insertions, 14 deletions

diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala
index b8f294c262..3b8cafb4a6 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala
@@ -39,13 +39,12 @@ import org.apache.hadoop.hive.serde2.io.{DateWritable, TimestampWritable}
 import org.apache.spark.SparkContext
 import org.apache.spark.annotation.Experimental
 import org.apache.spark.sql._
-import org.apache.spark.sql.catalyst.analysis.{Analyzer, EliminateSubQueries, OverrideCatalog, OverrideFunctionRegistry}
+import org.apache.spark.sql.catalyst.analysis._
 import org.apache.spark.sql.catalyst.plans.logical._
 import org.apache.spark.sql.execution.{ExecutedCommand, ExtractPythonUdfs, SetCommand}
 import org.apache.spark.sql.hive.client._
 import org.apache.spark.sql.hive.execution.{DescribeHiveTableCommand, HiveNativeCommand}
 import org.apache.spark.sql.sources.DataSourceStrategy
-import org.apache.spark.sql.catalyst.CatalystConf
 import org.apache.spark.sql.types._
 import org.apache.spark.util.Utils
 
@@ -374,10 +373,8 @@ class HiveContext(sc: SparkContext) extends SQLContext(sc) {
 
   // Note that HiveUDFs will be overridden by functions registered in this context.
   @transient
-  override protected[sql] lazy val functionRegistry =
-    new HiveFunctionRegistry with OverrideFunctionRegistry {
-      override def conf: CatalystConf = currentSession().conf
-    }
+  override protected[sql] lazy val functionRegistry: FunctionRegistry =
+    new HiveFunctionRegistry with OverrideFunctionRegistry
 
   /* An analyzer that uses the Hive metastore. */
   @transient
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUdfs.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUdfs.scala
index 01f47352b2..6e6ac987b6 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUdfs.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUdfs.scala
@@ -17,11 +17,8 @@
 
 package org.apache.spark.sql.hive
 
-import org.apache.hadoop.hive.ql.udf.generic.GenericUDAFEvaluator.AggregationBuffer
-import org.apache.hadoop.hive.ql.udf.generic.GenericUDFUtils.ConversionHelper
-import org.apache.spark.sql.AnalysisException
-
 import scala.collection.mutable.ArrayBuffer
+import scala.collection.JavaConversions._
 
 import org.apache.hadoop.hive.serde2.objectinspector.{ObjectInspector, ConstantObjectInspector}
 import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorFactory.ObjectInspectorOptions
@@ -30,8 +27,11 @@ import org.apache.hadoop.hive.ql.exec._
 import org.apache.hadoop.hive.ql.udf.{UDFType => HiveUDFType}
 import org.apache.hadoop.hive.ql.udf.generic._
 import org.apache.hadoop.hive.ql.udf.generic.GenericUDF._
+import org.apache.hadoop.hive.ql.udf.generic.GenericUDAFEvaluator.AggregationBuffer
+import org.apache.hadoop.hive.ql.udf.generic.GenericUDFUtils.ConversionHelper
 
 import org.apache.spark.Logging
+import org.apache.spark.sql.AnalysisException
 import org.apache.spark.sql.catalyst.analysis
 import org.apache.spark.sql.catalyst.errors.TreeNodeException
 import org.apache.spark.sql.catalyst.expressions._
@@ -40,20 +40,18 @@ import org.apache.spark.sql.catalyst.rules.Rule
 import org.apache.spark.sql.hive.HiveShim._
 import org.apache.spark.sql.types._
 
-/* Implicit conversions */
-import scala.collection.JavaConversions._
 
 private[hive] abstract class HiveFunctionRegistry
   extends analysis.FunctionRegistry with HiveInspectors {
 
   def getFunctionInfo(name: String): FunctionInfo = FunctionRegistry.getFunctionInfo(name)
 
-  def lookupFunction(name: String, children: Seq[Expression]): Expression = {
+  override def lookupFunction(name: String, children: Seq[Expression]): Expression = {
     // We only look it up to see if it exists, but do not include it in the HiveUDF since it is
     // not always serializable.
     val functionInfo: FunctionInfo =
       Option(FunctionRegistry.getFunctionInfo(name.toLowerCase)).getOrElse(
-        sys.error(s"Couldn't find function $name"))
+        throw new AnalysisException(s"undefined function $name"))
 
     val functionClassName = functionInfo.getFunctionClass.getName