apache/spark — pull request #2998 by OopsOutOfMemory (2014-10-29 12:09:33+00:00)
Title: [SQL] Add string operation function trim, ltrim, rtrim, length to support SparkSql (HiveQL)

@marmbrus @chenghao-intel
Add three string operation functions to support spark sql and hiveql.
eg:
sql("select trim(' a b ') from src ").collect() --> 'a b'
sql("select ltrim(' a b ') from src ").collect() --> 'a b '
sql("select rtrim(' a b ') from src ").collect() --> ' a b'
sql("select length('ab') from src ").collect() --> 2

And Rename the trait of stringOperations.scala.
I prefer to rename trait CaseConversionExpression to StringTransformationExpression, it is more make sence than before so that this trait can support more string transformation but not only caseconversion.

And also add a trait StringCalculationExpression that do string computation like length, indexof etc....