Package org.apache.drill.exec.expr.fn.impl

Class CharSubstring

java.lang.Object

org.apache.drill.exec.expr.fn.impl.CharSubstring

All Implemented Interfaces:

DrillFunc, DrillSimpleFunc

public class CharSubstring
extends Object
implements DrillSimpleFunc

Evaluate a substring expression for a given UTF-8 value; specifying the start position, and optionally the end position. - If the start position is negative, start from abs(start) characters from the end of the buffer. - If no length is specified, continue to the end of the string. - If the substring expression's length exceeds the value's upward bound, the value's length will be used. - If the substring is invalid, return an empty string. - NOTE: UTF-8 values range from 1 to 4 bytes per character, thus searching for the start, length, and negative length may result in 3 partial scans of the UTF-8 string. - TODO: implement optional length parameter

Constructor Summary

Constructors

Constructor	Description
CharSubstring()

Method Summary

Modifier and Type	Method	Description
void	eval()
void	setup()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

CharSubstring

public CharSubstring()

Method Details

setup

public void setup()

Specified by:

setup in interface DrillSimpleFunc

eval

public void eval()

Specified by:

eval in interface DrillSimpleFunc