Github user viirya commented on a diff in the pull request: https://github.com/apache/spark/pull/16476#discussion_r97796700 --- Diff: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/conditionalExpressions.scala --- @@ -340,3 +344,99 @@ object CaseKeyWhen { CaseWhen(cases, elseValue) } } + +/** + * A function that returns the index of expr in (expr1, expr2, ...) list or 0 if not found. + * It takes at least 2 parameters, and all parameters should be subtype of AtomicType or NullType. + * It's also acceptable to give parameters of different types. When the parameters have different + * types, comparing will be done based on type firstly. For example, ''999'' 's type is StringType, + * while 999's type is IntegerType, so that no further comparison need to be done since they have + * different types. + * If the search expression is NULL, the return value is 0 because NULL fails equality comparison + * with any value. + * To also point out, no implicit cast will be done in this expression. + */ +@ExpressionDescription( + usage = "_FUNC_(expr, expr1, expr2, ...) - Returns the index of expr in the expr1, expr2, ... or 0 if not found.", + extended = """ + Examples: + > SELECT _FUNC_(10, 9, 3, 10, 4); + 3 + > SELECT _FUNC_('a', 'b', 'c', 'd', 'a'); + 4 + > SELECT _FUNC_('999', 'a', 999, 9.99, '999'); + 4 + """) +case class Field(children: Seq[Expression]) extends Expression { + + /** Even if expr is not found in (expr1, expr2, ...) list, the value will be 0, not null */ + override def nullable: Boolean = false + override def foldable: Boolean = children.forall(_.foldable) + + private lazy val ordering = TypeUtils.getInterpretedOrdering(children(0).dataType) + + private val dataTypeMatchIndex: Array[Int] = children.zipWithIndex.tail.filter( + _._1.dataType.sameType(children.head.dataType)).map(_._2).toArray + + override def checkInputDataTypes(): TypeCheckResult = { + if (children.length <= 1) { + TypeCheckResult.TypeCheckFailure(s"FIELD requires at least 2 arguments") + } else if (!children.forall( + e => e.dataType.isInstanceOf[AtomicType] || e.dataType.isInstanceOf[NullType])) { + TypeCheckResult.TypeCheckFailure(s"FIELD requires all arguments to be of AtomicType") + } else + TypeCheckResult.TypeCheckSuccess + } + + override def dataType: DataType = IntegerType + override def eval(input: InternalRow): Any = { + val target = children.head.eval(input) + @tailrec def findEqual(index: Int): Int = { + if (index == dataTypeMatchIndex.length) { + 0 + } else { + val value = children(dataTypeMatchIndex(index)).eval(input) + if (value != null && ordering.equiv(target, value)) { + dataTypeMatchIndex(index) + } else { + findEqual(index + 1) + } + } + } + if (target == null) 0 else findEqual(index = 0) + } + + protected def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = { + val evalChildren = children.map(_.genCode(ctx)) + val target = evalChildren(0) + val targetDataType = children(0).dataType + val dataTypes = children.map(_.dataType) + + def updateEval(evalWithIndex: ((ExprCode, DataType), Int)): String = { + val ((eval, _), index) = evalWithIndex + s""" + ${eval.code} + if (${ctx.genEqual(targetDataType, eval.value, target.value)}) { + ${ev.value} = ${index}; + } + """ + } + + def genIfElseStructure(code1: String, code2: String): String = { + s""" + ${code1} + else { + ${code2} + } + """ + } + + ev.copy(code = s""" + ${target.code} --- End diff -- If `target.value == null`, we don't need to evaluate the expressions.
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