[SPARK-8749][SQL] Remove HiveTypeCoercion trait.

Moved all the rules into the companion object.

Author: Reynold Xin <rxin@databricks.com>

Closes #7147 from rxin/SPARK-8749 and squashes the following commits:

c1c6dc0 [Reynold Xin] [SPARK-8749][SQL] Remove HiveTypeCoercion trait.

3 files changed, 33 insertions, 44 deletions

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
index 117c87a785..15e84e68b9 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
@@ -43,7 +43,7 @@ class Analyzer(
     registry: FunctionRegistry,
     conf: CatalystConf,
     maxIterations: Int = 100)
-  extends RuleExecutor[LogicalPlan] with HiveTypeCoercion with CheckAnalysis {
+  extends RuleExecutor[LogicalPlan] with CheckAnalysis {
 
   def resolver: Resolver = {
     if (conf.caseSensitiveAnalysis) {
@@ -76,7 +76,7 @@ class Analyzer(
       ExtractWindowExpressions ::
       GlobalAggregates ::
       UnresolvedHavingClauseAttributes ::
-      typeCoercionRules ++
+      HiveTypeCoercion.typeCoercionRules ++
       extendedResolutionRules : _*)
   )
 
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercion.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercion.scala
index e525ad623f..a9d396d1fa 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercion.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercion.scala
@@ -22,7 +22,32 @@ import org.apache.spark.sql.catalyst.plans.logical.{LogicalPlan, Project, Union}
 import org.apache.spark.sql.catalyst.rules.Rule
 import org.apache.spark.sql.types._
 
+
+/**
+ * A collection of [[Rule Rules]] that can be used to coerce differing types that
+ * participate in operations into compatible ones.  Most of these rules are based on Hive semantics,
+ * but they do not introduce any dependencies on the hive codebase.  For this reason they remain in
+ * Catalyst until we have a more standard set of coercions.
+ */
 object HiveTypeCoercion {
+
+  val typeCoercionRules =
+    PropagateTypes ::
+      ConvertNaNs ::
+      InConversion ::
+      WidenTypes ::
+      PromoteStrings ::
+      DecimalPrecision ::
+      BooleanEquality ::
+      StringToIntegralCasts ::
+      FunctionArgumentConversion ::
+      CaseWhenCoercion ::
+      IfCoercion ::
+      Division ::
+      PropagateTypes ::
+      AddCastForAutoCastInputTypes ::
+      Nil
+
   // See https://cwiki.apache.org/confluence/display/Hive/LanguageManual+Types.
   // The conversion for integral and floating point types have a linear widening hierarchy:
   private val numericPrecedence =
@@ -79,7 +104,6 @@ object HiveTypeCoercion {
     })
   }
 
-
   /**
    * Find the tightest common type of a set of types by continuously applying
    * `findTightestCommonTypeOfTwo` on these types.
@@ -90,34 +114,6 @@ object HiveTypeCoercion {
       case Some(d) => findTightestCommonTypeOfTwo(d, c)
     })
   }
-}
-
-/**
- * A collection of [[Rule Rules]] that can be used to coerce differing types that
- * participate in operations into compatible ones.  Most of these rules are based on Hive semantics,
- * but they do not introduce any dependencies on the hive codebase.  For this reason they remain in
- * Catalyst until we have a more standard set of coercions.
- */
-trait HiveTypeCoercion {
-
-  import HiveTypeCoercion._
-
-  val typeCoercionRules =
-    PropagateTypes ::
-    ConvertNaNs ::
-    InConversion ::
-    WidenTypes ::
-    PromoteStrings ::
-    DecimalPrecision ::
-    BooleanEquality ::
-    StringToIntegralCasts ::
-    FunctionArgumentConversion ::
-    CaseWhenCoercion ::
-    IfCoercion ::
-    Division ::
-    PropagateTypes ::
-    AddCastForAutoCastInputTypes ::
-    Nil
 
   /**
    * Applies any changes to [[AttributeReference]] data types that are made by other rules to
@@ -202,8 +198,6 @@ trait HiveTypeCoercion {
    * - LongType to DoubleType
    */
   object WidenTypes extends Rule[LogicalPlan] {
-    import HiveTypeCoercion._
-
     def apply(plan: LogicalPlan): LogicalPlan = plan transform {
       // TODO: unions with fixed-precision decimals
       case u @ Union(left, right) if u.childrenResolved && !u.resolved =>
@@ -655,8 +649,6 @@ trait HiveTypeCoercion {
    * Coerces the type of different branches of a CASE WHEN statement to a common type.
    */
   object CaseWhenCoercion extends Rule[LogicalPlan] {
-    import HiveTypeCoercion._
-
     def apply(plan: LogicalPlan): LogicalPlan = plan transformAllExpressions {
       case c: CaseWhenLike if c.childrenResolved && !c.valueTypesEqual =>
         logDebug(s"Input values for null casting ${c.valueTypes.mkString(",")}")
@@ -714,7 +706,6 @@ trait HiveTypeCoercion {
    * [[AutoCastInputTypes]].
    */
   object AddCastForAutoCastInputTypes extends Rule[LogicalPlan] {
-
     def apply(plan: LogicalPlan): LogicalPlan = plan transformAllExpressions {
       // Skip nodes who's children have not been resolved yet.
       case e if !e.childrenResolved => e
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercionSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercionSuite.scala
index f7b8e21bed..eae3666595 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercionSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercionSuite.scala
@@ -113,8 +113,7 @@ class HiveTypeCoercionSuite extends PlanTest {
   }
 
   test("coalesce casts") {
-    val fac = new HiveTypeCoercion { }.FunctionArgumentConversion
-    ruleTest(fac,
+    ruleTest(HiveTypeCoercion.FunctionArgumentConversion,
       Coalesce(Literal(1.0)
         :: Literal(1)
         :: Literal.create(1.0, FloatType)
@@ -123,7 +122,7 @@ class HiveTypeCoercionSuite extends PlanTest {
         :: Cast(Literal(1), DoubleType)
         :: Cast(Literal.create(1.0, FloatType), DoubleType)
         :: Nil))
-    ruleTest(fac,
+    ruleTest(HiveTypeCoercion.FunctionArgumentConversion,
       Coalesce(Literal(1L)
         :: Literal(1)
         :: Literal(new java.math.BigDecimal("1000000000000000000000"))
@@ -135,7 +134,7 @@ class HiveTypeCoercionSuite extends PlanTest {
   }
 
   test("type coercion for If") {
-    val rule = new HiveTypeCoercion { }.IfCoercion
+    val rule = HiveTypeCoercion.IfCoercion
     ruleTest(rule,
       If(Literal(true), Literal(1), Literal(1L)),
       If(Literal(true), Cast(Literal(1), LongType), Literal(1L))
@@ -148,19 +147,18 @@ class HiveTypeCoercionSuite extends PlanTest {
   }
 
   test("type coercion for CaseKeyWhen") {
-    val cwc = new HiveTypeCoercion {}.CaseWhenCoercion
-    ruleTest(cwc,
+    ruleTest(HiveTypeCoercion.CaseWhenCoercion,
       CaseKeyWhen(Literal(1.toShort), Seq(Literal(1), Literal("a"))),
       CaseKeyWhen(Cast(Literal(1.toShort), IntegerType), Seq(Literal(1), Literal("a")))
     )
-    ruleTest(cwc,
+    ruleTest(HiveTypeCoercion.CaseWhenCoercion,
       CaseKeyWhen(Literal(true), Seq(Literal(1), Literal("a"))),
       CaseKeyWhen(Literal(true), Seq(Literal(1), Literal("a")))
     )
   }
 
   test("type coercion simplification for equal to") {
-    val be = new HiveTypeCoercion {}.BooleanEquality
+    val be = HiveTypeCoercion.BooleanEquality
 
     ruleTest(be,
       EqualTo(Literal(true), Literal(1)),