Github user tarekauel commented on a diff in the pull request:
https://github.com/apache/spark/pull/7208#discussion_r34008740
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringOperations.scala
---
@@ -298,3 +299,36 @@ case class StringLength(child: Expression) extends
UnaryExpression with ExpectsI
override def prettyName: String = "length"
}
+
+/**
+ * Returns string, with the first letter of each word in uppercase,
+ * all other letters in lowercase. Words are delimited by whitespace.
+ */
+case class InitCap(child: Expression) extends UnaryExpression with
ExpectsInputTypes {
+ override def dataType: DataType = StringType
+
+ override def inputTypes: Seq[DataType] = Seq(StringType)
+
+ override def eval(input: InternalRow): Any = {
+ val string = child.eval(input)
+ if (string == null) {
+ null
+ }
+ else if (string.toString.length == 0) {
+ return UTF8String.fromString(string.toString)
+ }
+ else {
+ val str: String = string.toString
+ val sb = new StringBuilder
--- End diff --
I don't understand your comment. What should I improve? StringBuilder of
Scala and Java are more or less identical,
see
https://github.com/scala/scala/blob/70f0b1ded880ec9b3a9478d02f1898fcfeee230c/src/library/scala/collection/mutable/StringBuilder.scala
Initialising the `StringBuilder` with the proper size has nothing to do
with blank strings or null checks. If you call a StringBuilder without a size,
it gets initialised with 16 (see
http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/8u40-b25/java/lang/StringBuilder.java#StringBuilder.%3Cinit%3E%28%29).
The result is that `StringBuilder` will reserve space for 16 characters. But
we know already the size of the result string (`str.length`). This allows us to
initialise the `StringBuilder` with the expected size. The advantage is that
`ensureCapacity` will never call `expandCapacity`, see
http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/8u40-b25/java/lang/AbstractStringBuilder.java#AbstractStringBuilder.ensureCapacity%28int%29
. If the string is not 16 characters long it saves some memory.
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