From 4cb764d312c0eb406d87d86cbd2faffe1bcf3350 Mon Sep 17 00:00:00 2001
From: Liang-Chi Hsieh <viirya@gmail.com>
Date: Wed, 10 Jun 2015 15:52:50 +0800
Subject: [PATCH] For comments.

---
 .../org/apache/spark/sql/catalyst/expressions/math.scala    | 3 +++
 .../spark/sql/catalyst/expressions/MathFunctionsSuite.scala | 3 ++-
 .../src/main/scala/org/apache/spark/sql/functions.scala     | 6 ++++--
 .../org/apache/spark/sql/DataFrameFunctionsSuite.scala      | 5 +++--
 4 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/math.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/math.scala
index 5938c8105f56d..2327836426379 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/math.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/math.scala
@@ -39,6 +39,9 @@ abstract class AbstractUnaryMathExpression[T, U](name: String)
   def funcName: String = name.toLowerCase
 }
 
+/**
+ * Base for [[AbstractUnaryMathExpression]] that accepts a Double and returns a Double.
+ */
 abstract class UnaryMathExpression(f: Double => Double, name: String)
   extends AbstractUnaryMathExpression[Double, Double](name) {
   self: Product =>
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/MathFunctionsSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/MathFunctionsSuite.scala
index 6bf9b933c6679..77163fb25e338 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/MathFunctionsSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/MathFunctionsSuite.scala
@@ -26,10 +26,11 @@ class MathFunctionsSuite extends SparkFunSuite with ExpressionEvalHelper {
    * Used for testing unary math expressions.
    *
    * @param c expression
-   * @param f The functions in scala.math
+   * @param f The functions in scala.math or elsewhere used to generate expected results
    * @param domain The set of values to run the function with
    * @param expectNull Whether the given values should return null or not
    * @tparam T Generic type for primitives
+   * @tparam U Generic type for the output of the given function `f`
    */
   private def testUnary[T, U](
       c: Expression => Expression,
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/functions.scala b/sql/core/src/main/scala/org/apache/spark/sql/functions.scala
index e401eb864583f..ef6a31ed3c56f 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/functions.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/functions.scala
@@ -1300,7 +1300,8 @@ object functions {
   def toRadians(columnName: String): Column = toRadians(Column(columnName))
 
   /**
-   * Computes the binary format of the given value.
+   * An expression that returns the string representation of the binary value of the given long
+   * column. For example, bin("12") returns "1100".
    *
    * @group math_funcs
    * @since 1.4.0
@@ -1308,7 +1309,8 @@ object functions {
   def bin(e: Column): Column = Bin(e.expr)
 
   /**
-   * Computes the binary format of the given value.
+   * An expression that returns the string representation of the binary value of the given long
+   * column. For example, bin("12") returns "1100".
    *
    * @group math_funcs
    * @since 1.4.0
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/DataFrameFunctionsSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/DataFrameFunctionsSuite.scala
index 10fd3c846874b..34f1ec8c2b357 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/DataFrameFunctionsSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/DataFrameFunctionsSuite.scala
@@ -94,8 +94,9 @@ class DataFrameFunctionsSuite extends QueryTest {
   }
 
   test("bin") {
+    val df = Seq[(Integer, Integer)]((12, null)).toDF("a", "b")
     checkAnswer(
-      testData2.select(bin($"a")),
-      testData2.collect().toSeq.map(r => Row(JLong.toBinaryString(r.getInt(0).toLong))))
+      df.select(bin("a"), bin("b")),
+      Row("1100", null))
   }
 }