override def toString()

in modules/spark-ext/spark/src/main/scala/org/apache/ignite/spark/impl/optimization/SystemExpressions.scala [73:121]
38 lines of code
17 McCabe index (conditional complexity)

    override def toString(expr: Expression, childToString: Expression ⇒ String, useQualifier: Boolean,
        useAlias: Boolean, caseSensitive: Boolean): Option[String] = expr match {
        case Coalesce(children) ⇒
            Some(s"COALESCE(${children.map(childToString(_)).mkString(", ")})")

        case Greatest(children) ⇒
            Some(s"GREATEST(${children.map(childToString(_)).mkString(", ")})")

        case IfNull(left, right, _) ⇒
            Some(s"IFNULL(${childToString(left)}, ${childToString(right)})")

        case Least(children) ⇒
            Some(s"LEAST(${children.map(childToString(_)).mkString(", ")})")

        case NullIf(left, right, _) ⇒
            Some(s"NULLIF(${childToString(left)}, ${childToString(right)})")

        case Nvl2(expr1, expr2, expr3, _) ⇒
            Some(s"NVL2(${childToString(expr1)}, ${childToString(expr2)}, ${childToString(expr3)})")

        case If(predicate, trueValue, falseValue) ⇒
            predicate match {
                case IsNotNull(child) ⇒
                    Some(s"NVL2(${childToString(child)}, ${childToString(trueValue)}, ${childToString(falseValue)})")

                case IsNull(child) ⇒
                    Some(s"NVL2(${childToString(child)}, ${childToString(falseValue)}, ${childToString(trueValue)})")

                case EqualTo(left, right) ⇒
                    trueValue match {
                        case Literal(null, _) ⇒
                            if (left == falseValue)
                                Some(s"NULLIF(${childToString(left)}, ${childToString(right)})")
                            else if (right == falseValue)
                                Some(s"NULLIF(${childToString(right)}, ${childToString(left)})")
                            else
                                throw new IgniteException(s"Expression not supported. $expr")

                        case _ ⇒
                            throw new IgniteException(s"Expression not supported. $expr")
                    }

                case _ ⇒
                    throw new IgniteException(s"Expression not supported. $expr")
            }

        case _ ⇒
            None
    }