org.diirt.datasource.formula

Class ExpressionLanguage

java.lang.Object

org.diirt.datasource.formula.ExpressionLanguage

public class ExpressionLanguage
extends Object

Support for formula expressions.

Author:

carcassi

Method Summary

Modifier and Type	Method and Description
static String	channelFromFormula(String formula) If the formula represents a single channels it returns the name, null otherwise.
static DesiredRateReadWriteExpression<?,Object>	formula(FormulaAst ast) Returns the expression corresponding to the formula represented by the given Abstract Syntax Tree.
static DesiredRateReadWriteExpression<?,Object>	formula(String formula) Returns the expression that will return the live value of the given formula.
static <T> DesiredRateExpression<T>	formula(String formula, Class<T> readType) An expression that returns the value of the formula making sure it's of the given type.
static DesiredRateExpression<?>	formulaArg(String formula) An expression that returns the value of the formula and return null for empty or null formula.

Methods inherited from class java.lang.Object

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

Method Detail

channelFromFormula

public static String channelFromFormula(String formula)

If the formula represents a single channels it returns the name, null otherwise.

Parameters:

formula - the formula to parse

Returns:

the channel it represents or null

formula

public static DesiredRateReadWriteExpression<?,Object> formula(String formula)

Returns the expression that will return the live value of the given formula.

Parameters:

formula - the formula to parse

Returns:

an expression for the formula

formula

public static DesiredRateReadWriteExpression<?,Object> formula(FormulaAst ast)

Returns the expression corresponding to the formula represented by the given Abstract Syntax Tree.

Parameters:

ast - a formula abstract syntax tree

Returns:

an expression for the formula

formulaArg

public static DesiredRateExpression<?> formulaArg(String formula)

An expression that returns the value of the formula and return null for empty or null formula.

Some expressions allow for null expression arguments to handle optional elements. In those cases, using this method makes undeclared arguments fall through.

Parameters:

formula - the formula, can be null

Returns:

an expression of the given type; null if formula is null or empty

formula

public static <T> DesiredRateExpression<T> formula(String formula,
                                                   Class<T> readType)

An expression that returns the value of the formula making sure it's of the given type.

Type Parameters:

T - the type to read

Parameters:

formula - the formula

readType - the type to read

Returns:

an expression of the given type