com.google.visualization.datasource.query.scalarfunction
Class Lower

java.lang.Object
  com.google.visualization.datasource.query.scalarfunction.Lower

All Implemented Interfaces:

ScalarFunction

public class Lower
extends java.lang.Object
implements ScalarFunction

A unary scalar function that changes text to lower case.

Author:

Yaniv S.

Method Summary

Value	evaluate(java.util.List<Value> values) Executes the scalar function on the given list of values, and returns the Value which is the result of the execution the function.
java.lang.String	getFunctionName() Returns the function's name.
static Lower	getInstance()
ValueType	getReturnType(java.util.List<ValueType> types) Returns the return type of the function, given specific types for its parameters.
java.lang.String	toQueryString(java.util.List<java.lang.String> argumentsQueryStrings) Returns a string that when given to the query parser will yield a similar scalar function.
void	validateParameters(java.util.List<ValueType> types) Validates that the number and types of the function parameters are valid.

Methods inherited from class java.lang.Object

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

Method Detail

getInstance

public static Lower getInstance()

Returns:

The singleton instance of this class.

getFunctionName

public java.lang.String getFunctionName()

Returns the function's name.

Specified by:

getFunctionName in interface ScalarFunction

Returns:

The function's name.

evaluate

public Value evaluate(java.util.List<Value> values)

Description copied from interface: ScalarFunction

Executes the scalar function on the given list of values, and returns the Value which is the result of the execution the function.

Specified by:

evaluate in interface ScalarFunction

Parameters:

values - A list that contains one text value.

Returns:

A lower-case version of the input text value.

getReturnType

public ValueType getReturnType(java.util.List<ValueType> types)

Description copied from interface: ScalarFunction

Returns the return type of the function, given specific types for its parameters. Some functions can be polymorphic, i.e., their return type changes according to the types of their parameters.

Specified by:

getReturnType in interface ScalarFunction

Parameters:

types - A list of the types of the function's parameters.

Returns:

The return type of this function - TEXT.

validateParameters

public void validateParameters(java.util.List<ValueType> types)
                        throws InvalidQueryException

Validates that the number and types of the function parameters are valid. Throws an exception if they are not valid.

Specified by:

validateParameters in interface ScalarFunction

Parameters:

types - The given types of the function's parameters.

Throws:

InvalidQueryException - Thrown when the parameters are invalid.

toQueryString

public java.lang.String toQueryString(java.util.List<java.lang.String> argumentsQueryStrings)

Returns a string that when given to the query parser will yield a similar scalar function. Takes as arguments the query strings of the arguments.

Specified by:

toQueryString in interface ScalarFunction

Parameters:

argumentsQueryStrings - The query strings of the actual arguments.

Returns:

The query string.