[SPARK-9242] [SQL] Audit UDAF interface.

A few minor changes:

1. Improved documentation
2. Rename apply(distinct....) to distinct.
3. Changed MutableAggregationBuffer from a trait to an abstract class.
4. Renamed returnDataType to dataType to be more consistent with other expressions.

And unrelated to UDAFs:

1. Renamed file names in expressions to use suffix "Expressions" to be more consistent.
2. Moved regexp related expressions out to its own file.
3. Renamed StringComparison => StringPredicate.

Author: Reynold Xin <rxin@databricks.com>

Closes #8321 from rxin/SPARK-9242.

3 files changed, 3 insertions, 3 deletions

diff --git a/sql/hive/src/test/java/test/org/apache/spark/sql/hive/JavaDataFrameSuite.java b/sql/hive/src/test/java/test/org/apache/spark/sql/hive/JavaDataFrameSuite.java
index 21b053f07a..a30dfa554e 100644
--- a/sql/hive/src/test/java/test/org/apache/spark/sql/hive/JavaDataFrameSuite.java
+++ b/sql/hive/src/test/java/test/org/apache/spark/sql/hive/JavaDataFrameSuite.java
@@ -92,7 +92,7 @@ public class JavaDataFrameSuite {
     DataFrame aggregatedDF =
       df.groupBy()
         .agg(
-          udaf.apply(true, col("value")),
+          udaf.distinct(col("value")),
           udaf.apply(col("value")),
           registeredUDAF.apply(col("value")),
           callUDF("mydoublesum", col("value")));
diff --git a/sql/hive/src/test/java/test/org/apache/spark/sql/hive/aggregate/MyDoubleAvg.java b/sql/hive/src/test/java/test/org/apache/spark/sql/hive/aggregate/MyDoubleAvg.java
index a2247e3da1..2961b803f1 100644
--- a/sql/hive/src/test/java/test/org/apache/spark/sql/hive/aggregate/MyDoubleAvg.java
+++ b/sql/hive/src/test/java/test/org/apache/spark/sql/hive/aggregate/MyDoubleAvg.java
@@ -65,7 +65,7 @@ public class MyDoubleAvg extends UserDefinedAggregateFunction {
     return _bufferSchema;
   }
 
-  @Override public DataType returnDataType() {
+  @Override public DataType dataType() {
     return _returnDataType;
   }
 
diff --git a/sql/hive/src/test/java/test/org/apache/spark/sql/hive/aggregate/MyDoubleSum.java b/sql/hive/src/test/java/test/org/apache/spark/sql/hive/aggregate/MyDoubleSum.java
index da29e24d26..c71882a6e7 100644
--- a/sql/hive/src/test/java/test/org/apache/spark/sql/hive/aggregate/MyDoubleSum.java
+++ b/sql/hive/src/test/java/test/org/apache/spark/sql/hive/aggregate/MyDoubleSum.java
@@ -60,7 +60,7 @@ public class MyDoubleSum extends UserDefinedAggregateFunction {
     return _bufferSchema;
   }
 
-  @Override public DataType returnDataType() {
+  @Override public DataType dataType() {
     return _returnDataType;
   }