Github user tarekauel commented on a diff in the pull request:
https://github.com/apache/spark/pull/7208#discussion_r33947548
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringOperations.scala
---
@@ -298,3 +299,56 @@ case class StringLength(child: Expression) extends
UnaryExpression with ExpectsI
override def prettyName: String = "length"
}
+
+/**
+ * A function that return soundex code of the given string expression.
+ */
+case class SoundEx(child: Expression) extends UnaryExpression with
ExpectsInputTypes {
+ @transient lazy val so = new Soundex
+
+ 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 {
+ val str: String = string.toString
+ UTF8String.fromString(so.encode(str))
+ }
+ }
+}
+
+/**
+ * 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 {
+ @transient lazy val so = new Soundex
+
+ 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 {
+ val str: String = string.toString
+ val sb = new StringBuilder
--- End diff --
On the surface this might be true, but look in the implementation
http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/8u40-b25/java/lang/AbstractStringBuilder.java#AbstractStringBuilder.append%28java.lang.CharSequence%2Cint%2Cint%29
http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/8u40-b25/java/lang/AbstractStringBuilder.java#AbstractStringBuilder.charAt%28int%29
`append` calls `charAt` `length` times. We would save every `chartAt` call
that is triggered when you replace a character. The second optimisation is to
initialise `StringBuilder` with `str.length`. This avoids that `StringBuilder`
has to expand it's size.
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