Github user hvanhovell commented on a diff in the pull request:
https://github.com/apache/spark/pull/18019#discussion_r117378356
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringExpressions.scala
---
@@ -1268,6 +1268,59 @@ case class Ascii(child: Expression) extends
UnaryExpression with ImplicitCastInp
}
/**
+ * Returns the ASCII character having the binary equivalent to n.
+ * If n is larger than 256 the result is equivalent to chr(n % 256)
+ */
+// scalastyle:off line.size.limit
+@ExpressionDescription(
+ usage = "_FUNC_(expr) - Returns the ASCII character having the binary
equivalent to `expr`. If n is larger than 256 the result is equivalent to chr(n
% 256)",
+ extended = """
+ Examples:
+ > SELECT _FUNC_(65);
+ A
+ """)
+// scalastyle:on line.size.limit
+case class Chr(child: Expression) extends UnaryExpression with
ImplicitCastInputTypes {
+
+ override def dataType: DataType = StringType
+ override def inputTypes: Seq[DataType] = Seq(LongType)
+
+ protected override def nullSafeEval(value: Any): Any = {
+ val longVal = value.asInstanceOf[Long]
+ val shortVal = if (longVal > 255) (longVal % 256).toShort else
longVal.toShort
+ val stringVal = if (shortVal == 0) {
+ String.valueOf('\u0000')
+ } else if (shortVal < 0) {
+ ""
+ } else {
+ shortVal.toChar.toString
+ }
+ UTF8String.fromString(stringVal)
+ }
+
+ override def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
+ defineCodeGen(ctx, ev, lon => {
+ s"""
+ long longVal = (long)${lon};
+ short shortVal;
+ if (longVal > 255) {
--- End diff --
It might be easier to something like this:
```java
if (lon < 0) {
${ev.value} = UTF8String.fromString(""); // This should be put in a
constant
} else if (($lon & 0xFF) == 0) {
${ev.value} = UTF8String.fromString("\u0000"); // This should be put in
a variable
} else {
char c = (char)($lon & 0xFF);
// This is quite slow, it might be better to create the bytes directly.
${ev.value} = UTF8String.fromString(String.valueOf(c));
}
```
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