Github user davies commented on a diff in the pull request:
https://github.com/apache/spark/pull/6762#discussion_r34216355
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringOperations.scala
---
@@ -188,6 +189,302 @@ case class EndsWith(left: Expression, right:
Expression)
}
/**
+ * A function that trim the spaces from both ends for the specified string.
+ */
+case class StringTrim(child: Expression)
+ extends UnaryExpression with String2StringExpression {
+
+ def convert(v: UTF8String): UTF8String = v.trim()
+
+ override def toString: String = s"TRIM($child)"
+
+ override def genCode(ctx: CodeGenContext, ev: GeneratedExpressionCode):
String = {
+ defineCodeGen(ctx, ev, c => s"($c).trim()")
+ }
+}
+
+/**
+ * A function that trim the spaces from left end for given string.
+ */
+case class StringTrimLeft(child: Expression)
+ extends UnaryExpression with String2StringExpression {
+
+ def convert(v: UTF8String): UTF8String = v.trimLeft()
+
+ override def toString: String = s"LTRIM($child)"
+
+ override def genCode(ctx: CodeGenContext, ev: GeneratedExpressionCode):
String = {
+ defineCodeGen(ctx, ev, c => s"($c).trimLeft()")
+ }
+}
+
+/**
+ * A function that trim the spaces from right end for given string.
+ */
+case class StringTrimRight(child: Expression)
+ extends UnaryExpression with String2StringExpression {
+
+ def convert(v: UTF8String): UTF8String = v.trimRight()
+
+ override def toString: String = s"RTRIM($child)"
+
+ override def genCode(ctx: CodeGenContext, ev: GeneratedExpressionCode):
String = {
+ defineCodeGen(ctx, ev, c => s"($c).trimRight()")
+ }
+}
+
+/**
+ * A function that returns the position of the first occurrence of substr
in the given string.
+ * Returns null if either of the arguments are null and
+ * returns 0 if substr could not be found in str.
+ *
+ * NOTE: that this is not zero based, but 1-based index. The first
character in str has index 1.
+ */
+case class StringInstr(str: Expression, substr: Expression)
+ extends BinaryExpression with ExpectsInputTypes {
+
+ override def left: Expression = str
+ override def right: Expression = substr
+ override def dataType: DataType = IntegerType
+ override def inputTypes: Seq[DataType] = Seq(StringType, StringType)
+
+ override def nullSafeEval(string: Any, sub: Any): Any = {
+ string.asInstanceOf[UTF8String].instr(sub.asInstanceOf[UTF8String], 0)
+ 1
+ }
+
+ override def toString: String = s"INSTR($str, $substr)"
+
+ override def genCode(ctx: CodeGenContext, ev: GeneratedExpressionCode):
String = {
+ defineCodeGen(ctx, ev, (l, r) =>
+ s"($l).instr($r, 0) + 1")
+ }
+}
+
+/**
+ * A function that returns the position of the first occurrence of substr
+ * in given string after position pos.
+ */
+case class StringLocate(substr: Expression, str: Expression, start:
Expression)
+ extends Expression with ExpectsInputTypes {
+
+ def this(substr: Expression, str: Expression) = {
+ this(substr, str, Literal(0))
+ }
+
+ override def children: Seq[Expression] = substr :: str :: start :: Nil
+ override def foldable: Boolean = children.forall(_.foldable)
+ override def nullable: Boolean = substr.nullable || str.nullable
+ override def dataType: DataType = IntegerType
+ override def inputTypes: Seq[DataType] = Seq(StringType, StringType,
IntegerType)
+
+ override def eval(input: InternalRow): Any = {
+ val s = start.eval(input)
+ if (s == null) {
+ // if the start position is null, we need to return 0, (keep it
conform to Hive)
+ 0
+ } else {
+ val r = substr.eval(input)
+ if (r == null) {
+ null
+ } else {
+ val l = str.eval(input)
+ if (l == null) {
--- End diff --
Then we should update `nullable ` to reflect that.
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