[SPARK-14710][SQL] Rename gen/genCode to genCode/doGenCode to better reflect the semantics

## What changes were proposed in this pull request?

Per rxin's suggestions, this patch renames `s/gen/genCode` and `s/genCode/doGenCode` to better reflect the semantics of these 2 function calls.

## How was this patch tested?

N/A (refactoring only)

Author: Sameer Agarwal <sameer@databricks.com>

Closes #12475 from sameeragarwal/gencode.

9 files changed, 35 insertions, 32 deletions

diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/ExistingRDD.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/ExistingRDD.scala
index 392c48fb7b..3dc2aa33df 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/ExistingRDD.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/ExistingRDD.scala
@@ -192,7 +192,7 @@ private[sql] case class RowDataSourceScan(
     val row = ctx.freshName("row")
     ctx.INPUT_ROW = row
     ctx.currentVars = null
-    val columnsRowInput = exprRows.map(_.gen(ctx))
+    val columnsRowInput = exprRows.map(_.genCode(ctx))
     val inputRow = if (outputUnsafeRows) row else null
     s"""
        |while ($input.hasNext()) {
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/Expand.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/Expand.scala
index bd23b7e3ad..cc0382e5d4 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/Expand.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/Expand.scala
@@ -149,7 +149,7 @@ case class Expand(
       val firstExpr = projections.head(col)
       if (sameOutput(col)) {
         // This column is the same across all output rows. Just generate code for it here.
-        BindReferences.bindReference(firstExpr, child.output).gen(ctx)
+        BindReferences.bindReference(firstExpr, child.output).genCode(ctx)
       } else {
         val isNull = ctx.freshName("isNull")
         val value = ctx.freshName("value")
@@ -166,7 +166,7 @@ case class Expand(
       var updateCode = ""
       for (col <- exprs.indices) {
         if (!sameOutput(col)) {
-          val ev = BindReferences.bindReference(exprs(col), child.output).gen(ctx)
+          val ev = BindReferences.bindReference(exprs(col), child.output).genCode(ctx)
           updateCode +=
             s"""
                |${ev.code}
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/WholeStageCodegen.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/WholeStageCodegen.scala
index 29acc38ab3..12d08c8c45 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/WholeStageCodegen.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/WholeStageCodegen.scala
@@ -118,7 +118,7 @@ trait CodegenSupport extends SparkPlan {
         ctx.currentVars = null
         ctx.INPUT_ROW = row
         output.zipWithIndex.map { case (attr, i) =>
-          BoundReference(i, attr.dataType, attr.nullable).gen(ctx)
+          BoundReference(i, attr.dataType, attr.nullable).genCode(ctx)
         }
       } else {
         assert(outputVars != null)
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/TungstenAggregate.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/TungstenAggregate.scala
index f585759e58..d819a65993 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/TungstenAggregate.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/TungstenAggregate.scala
@@ -165,7 +165,7 @@ case class TungstenAggregate(
       ctx.addMutableState("boolean", isNull, "")
       ctx.addMutableState(ctx.javaType(e.dataType), value, "")
       // The initial expression should not access any column
-      val ev = e.gen(ctx)
+      val ev = e.genCode(ctx)
       val initVars = s"""
          | $isNull = ${ev.isNull};
          | $value = ${ev.value};
@@ -179,13 +179,13 @@ case class TungstenAggregate(
       // evaluate aggregate results
       ctx.currentVars = bufVars
       val aggResults = functions.map(_.evaluateExpression).map { e =>
-        BindReferences.bindReference(e, aggregateBufferAttributes).gen(ctx)
+        BindReferences.bindReference(e, aggregateBufferAttributes).genCode(ctx)
       }
       val evaluateAggResults = evaluateVariables(aggResults)
       // evaluate result expressions
       ctx.currentVars = aggResults
       val resultVars = resultExpressions.map { e =>
-        BindReferences.bindReference(e, aggregateAttributes).gen(ctx)
+        BindReferences.bindReference(e, aggregateAttributes).genCode(ctx)
       }
       (resultVars, s"""
         |$evaluateAggResults
@@ -196,7 +196,7 @@ case class TungstenAggregate(
       (bufVars, "")
     } else {
       // no aggregate function, the result should be literals
-      val resultVars = resultExpressions.map(_.gen(ctx))
+      val resultVars = resultExpressions.map(_.genCode(ctx))
       (resultVars, evaluateVariables(resultVars))
     }
 
@@ -240,7 +240,7 @@ case class TungstenAggregate(
     }
     ctx.currentVars = bufVars ++ input
     // TODO: support subexpression elimination
-    val aggVals = updateExpr.map(BindReferences.bindReference(_, inputAttrs).gen(ctx))
+    val aggVals = updateExpr.map(BindReferences.bindReference(_, inputAttrs).genCode(ctx))
     // aggregate buffer should be updated atomic
     val updates = aggVals.zipWithIndex.map { case (ev, i) =>
       s"""
@@ -394,25 +394,25 @@ case class TungstenAggregate(
       ctx.currentVars = null
       ctx.INPUT_ROW = keyTerm
       val keyVars = groupingExpressions.zipWithIndex.map { case (e, i) =>
-        BoundReference(i, e.dataType, e.nullable).gen(ctx)
+        BoundReference(i, e.dataType, e.nullable).genCode(ctx)
       }
       val evaluateKeyVars = evaluateVariables(keyVars)
       ctx.INPUT_ROW = bufferTerm
       val bufferVars = aggregateBufferAttributes.zipWithIndex.map { case (e, i) =>
-        BoundReference(i, e.dataType, e.nullable).gen(ctx)
+        BoundReference(i, e.dataType, e.nullable).genCode(ctx)
       }
       val evaluateBufferVars = evaluateVariables(bufferVars)
       // evaluate the aggregation result
       ctx.currentVars = bufferVars
       val aggResults = declFunctions.map(_.evaluateExpression).map { e =>
-        BindReferences.bindReference(e, aggregateBufferAttributes).gen(ctx)
+        BindReferences.bindReference(e, aggregateBufferAttributes).genCode(ctx)
       }
       val evaluateAggResults = evaluateVariables(aggResults)
       // generate the final result
       ctx.currentVars = keyVars ++ aggResults
       val inputAttrs = groupingAttributes ++ aggregateAttributes
       val resultVars = resultExpressions.map { e =>
-        BindReferences.bindReference(e, inputAttrs).gen(ctx)
+        BindReferences.bindReference(e, inputAttrs).genCode(ctx)
       }
       s"""
        $evaluateKeyVars
@@ -437,7 +437,7 @@ case class TungstenAggregate(
       ctx.INPUT_ROW = keyTerm
       ctx.currentVars = null
       val eval = resultExpressions.map{ e =>
-        BindReferences.bindReference(e, groupingAttributes).gen(ctx)
+        BindReferences.bindReference(e, groupingAttributes).genCode(ctx)
       }
       consume(ctx, eval)
     }
@@ -576,7 +576,7 @@ case class TungstenAggregate(
     // generate hash code for key
     val hashExpr = Murmur3Hash(groupingExpressions, 42)
     ctx.currentVars = input
-    val hashEval = BindReferences.bindReference(hashExpr, child.output).gen(ctx)
+    val hashEval = BindReferences.bindReference(hashExpr, child.output).genCode(ctx)
 
     val inputAttr = aggregateBufferAttributes ++ child.output
     ctx.currentVars = new Array[ExprCode](aggregateBufferAttributes.length) ++ input
@@ -613,7 +613,8 @@ case class TungstenAggregate(
     val updateRowInVectorizedHashMap: Option[String] = {
       if (isVectorizedHashMapEnabled) {
         ctx.INPUT_ROW = vectorizedRowBuffer
-        val vectorizedRowEvals = updateExpr.map(BindReferences.bindReference(_, inputAttr).gen(ctx))
+        val vectorizedRowEvals =
+          updateExpr.map(BindReferences.bindReference(_, inputAttr).genCode(ctx))
         val updateVectorizedRow = vectorizedRowEvals.zipWithIndex.map { case (ev, i) =>
           val dt = updateExpr(i).dataType
           ctx.updateColumn(vectorizedRowBuffer, dt, i, ev, updateExpr(i).nullable)
@@ -663,7 +664,7 @@ case class TungstenAggregate(
     val updateRowInUnsafeRowMap: String = {
       ctx.INPUT_ROW = unsafeRowBuffer
       val unsafeRowBufferEvals =
-        updateExpr.map(BindReferences.bindReference(_, inputAttr).gen(ctx))
+        updateExpr.map(BindReferences.bindReference(_, inputAttr).genCode(ctx))
       val updateUnsafeRowBuffer = unsafeRowBufferEvals.zipWithIndex.map { case (ev, i) =>
         val dt = updateExpr(i).dataType
         ctx.updateColumn(unsafeRowBuffer, dt, i, ev, updateExpr(i).nullable)
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/basicOperators.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/basicOperators.scala
index 344aaff348..c689fc3fbb 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/basicOperators.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/basicOperators.scala
@@ -53,7 +53,7 @@ case class Project(projectList: Seq[NamedExpression], child: SparkPlan)
     val exprs = projectList.map(x =>
       ExpressionCanonicalizer.execute(BindReferences.bindReference(x, child.output)))
     ctx.currentVars = input
-    val resultVars = exprs.map(_.gen(ctx))
+    val resultVars = exprs.map(_.genCode(ctx))
     // Evaluation of non-deterministic expressions can't be deferred.
     val nonDeterministicAttrs = projectList.filterNot(_.deterministic).map(_.toAttribute)
     s"""
@@ -122,7 +122,7 @@ case class Filter(condition: Expression, child: SparkPlan)
       val evaluated = evaluateRequiredVariables(child.output, in, c.references)
 
       // Generate the code for the predicate.
-      val ev = ExpressionCanonicalizer.execute(bound).gen(ctx)
+      val ev = ExpressionCanonicalizer.execute(bound).genCode(ctx)
       val nullCheck = if (bound.nullable) {
         s"${ev.isNull} || "
       } else {
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/BroadcastHashJoin.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/BroadcastHashJoin.scala
index a8f854136c..b94b0d26b2 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/BroadcastHashJoin.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/BroadcastHashJoin.scala
@@ -118,7 +118,7 @@ case class BroadcastHashJoin(
     ctx.currentVars = input
     if (streamedKeys.length == 1 && streamedKeys.head.dataType == LongType) {
       // generate the join key as Long
-      val ev = streamedKeys.head.gen(ctx)
+      val ev = streamedKeys.head.genCode(ctx)
       (ev, ev.isNull)
     } else {
       // generate the join key as UnsafeRow
@@ -134,7 +134,7 @@ case class BroadcastHashJoin(
     ctx.currentVars = null
     ctx.INPUT_ROW = matched
     buildPlan.output.zipWithIndex.map { case (a, i) =>
-      val ev = BoundReference(i, a.dataType, a.nullable).gen(ctx)
+      val ev = BoundReference(i, a.dataType, a.nullable).genCode(ctx)
       if (joinType == Inner) {
         ev
       } else {
@@ -170,7 +170,8 @@ case class BroadcastHashJoin(
       val eval = evaluateRequiredVariables(buildPlan.output, buildVars, expr.references)
       // filter the output via condition
       ctx.currentVars = input ++ buildVars
-      val ev = BindReferences.bindReference(expr, streamedPlan.output ++ buildPlan.output).gen(ctx)
+      val ev =
+        BindReferences.bindReference(expr, streamedPlan.output ++ buildPlan.output).genCode(ctx)
       s"""
          |$eval
          |${ev.code}
@@ -244,7 +245,8 @@ case class BroadcastHashJoin(
       // evaluate the variables from build side that used by condition
       val eval = evaluateRequiredVariables(buildPlan.output, buildVars, expr.references)
       ctx.currentVars = input ++ buildVars
-      val ev = BindReferences.bindReference(expr, streamedPlan.output ++ buildPlan.output).gen(ctx)
+      val ev =
+        BindReferences.bindReference(expr, streamedPlan.output ++ buildPlan.output).genCode(ctx)
       s"""
          |boolean $conditionPassed = true;
          |${eval.trim}
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/SortMergeJoin.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/SortMergeJoin.scala
index 0e7b2f2f31..443a7b43b6 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/SortMergeJoin.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/SortMergeJoin.scala
@@ -226,7 +226,7 @@ case class SortMergeJoin(
       keys: Seq[Expression],
       input: Seq[Attribute]): Seq[ExprCode] = {
     ctx.INPUT_ROW = row
-    keys.map(BindReferences.bindReference(_, input).gen(ctx))
+    keys.map(BindReferences.bindReference(_, input).genCode(ctx))
   }
 
   private def copyKeys(ctx: CodegenContext, vars: Seq[ExprCode]): Seq[ExprCode] = {
@@ -376,7 +376,7 @@ case class SortMergeJoin(
   private def createRightVar(ctx: CodegenContext, rightRow: String): Seq[ExprCode] = {
     ctx.INPUT_ROW = rightRow
     right.output.zipWithIndex.map { case (a, i) =>
-      BoundReference(i, a.dataType, a.nullable).gen(ctx)
+      BoundReference(i, a.dataType, a.nullable).genCode(ctx)
     }
   }
 
@@ -427,7 +427,7 @@ case class SortMergeJoin(
       val (rightBefore, rightAfter) = splitVarsByCondition(right.output, rightVars)
       // Generate code for condition
       ctx.currentVars = leftVars ++ rightVars
-      val cond = BindReferences.bindReference(condition.get, output).gen(ctx)
+      val cond = BindReferences.bindReference(condition.get, output).genCode(ctx)
       // evaluate the columns those used by condition before loop
       val before = s"""
            |boolean $loaded = false;
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/objects.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/objects.scala
index d2ab18ef0e..784b1e8c26 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/objects.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/objects.scala
@@ -48,7 +48,7 @@ case class DeserializeToObject(
     val bound = ExpressionCanonicalizer.execute(
       BindReferences.bindReference(deserializer, child.output))
     ctx.currentVars = input
-    val resultVars = bound.gen(ctx) :: Nil
+    val resultVars = bound.genCode(ctx) :: Nil
     consume(ctx, resultVars)
   }
 
@@ -82,7 +82,7 @@ case class SerializeFromObject(
       ExpressionCanonicalizer.execute(BindReferences.bindReference(expr, child.output))
     }
     ctx.currentVars = input
-    val resultVars = bound.map(_.gen(ctx))
+    val resultVars = bound.map(_.genCode(ctx))
     consume(ctx, resultVars)
   }
 
@@ -173,13 +173,13 @@ case class MapElements(
     val bound = ExpressionCanonicalizer.execute(
       BindReferences.bindReference(callFunc, child.output))
     ctx.currentVars = input
-    val evaluated = bound.gen(ctx)
+    val evaluated = bound.genCode(ctx)
 
     val resultObj = LambdaVariable(evaluated.value, evaluated.isNull, resultObjType)
     val outputFields = serializer.map(_ transform {
       case _: BoundReference => resultObj
     })
-    val resultVars = outputFields.map(_.gen(ctx))
+    val resultVars = outputFields.map(_.genCode(ctx))
     s"""
       ${evaluated.code}
       ${consume(ctx, resultVars)}
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/subquery.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/subquery.scala
index 4b3091ba22..03defc121c 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/subquery.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/subquery.scala
@@ -54,8 +54,8 @@ case class ScalarSubquery(
 
   override def eval(input: InternalRow): Any = result
 
-  override def genCode(ctx: CodegenContext, ev: ExprCode): String = {
-    Literal.create(result, dataType).genCode(ctx, ev)
+  override def doGenCode(ctx: CodegenContext, ev: ExprCode): String = {
+    Literal.create(result, dataType).doGenCode(ctx, ev)
   }
 }