Package com.randomnoun.common.jexl.eval

Class EvalContext

java.lang.Object

com.randomnoun.common.jexl.eval.EvalContext

public class EvalContext
extends Object

Provides variables and functions for an expression to be evaluated with

Author:

knoxg

Constructor Summary

Constructors

Constructor	Description
EvalContext()

Method Summary

Modifier and Type	Method	Description
Object	getFunction(String function)	Returns the value of a variable (used in the Evaluator class).
Object	getVariable(String varName)	Returns the value of a variable (used in the Evaluator class).
Object	getVariableComponent(Object varObj, String baseName, String componentName)	Returns a component of a compound variable (which must currently be a Map object).
boolean	hasVariable(String varName)	Returns true if the variable exists.
boolean	hasVariableComponent(Object varObj, String baseName, String componentName)	DOCUMENT ME!
void	setFunction(String name, EvalFunction function)	Set a specific function
void	setFunctions(Map<String,EvalFunction> functions)	Sets all variables accessible to an expression.
void	setVariable(String name, Object value)	Set a specific variable binding
void	setVariables(Map<String,Object> variables)	Sets all variables accessable to an expression.
void	unsetVariable(String name)	Removes a specific variable binding

Methods inherited from class java.lang.Object

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

Constructor Details

EvalContext

public EvalContext()

Method Details

setVariables

public void setVariables(Map<String,Object> variables)

Sets all variables accessable to an expression.

setVariable

public void setVariable(String name,
 Object value)

Set a specific variable binding

unsetVariable

public void unsetVariable(String name)

Removes a specific variable binding

getVariable

public Object getVariable(String varName)

Returns the value of a variable (used in the Evaluator class).

hasVariable

public boolean hasVariable(String varName)

Returns true if the variable exists.

setFunctions

public void setFunctions(Map<String,EvalFunction> functions)

Sets all variables accessible to an expression.

setFunction

public void setFunction(String name,
 EvalFunction function)

Set a specific function

getFunction

public Object getFunction(String function)

Returns the value of a variable (used in the Evaluator class).

getVariableComponent

public Object getVariableComponent(Object varObj,
 String baseName,
 String componentName)
                            throws EvalException

Returns a component of a compound variable (which must currently be a Map object). The component name is the key of the map. e.g. if a Map variable called 'x' contains a key 'y' with the value 'z', then the following code could be used to retrieve this value:

   x = evalContext.getVariable("x")
   value = evalContext.getVariableComponent(x, "x", "y")  // evaluates to 'z'
 

Note that this is only useful in the Evaluator to retrieve compound variables, outside the evaluator you should be just be evaluating the value "x.y" directly.

Parameters:

varObj - the compound variable value that is being evaluated (as returned by the getVariable() method)

baseName - the name of the variable

componentName - the name of the component in varObj to return.

Throws:

EvalException

hasVariableComponent

public boolean hasVariableComponent(Object varObj,
 String baseName,
 String componentName)

DOCUMENT ME!

Parameters:

varObj - DOCUMENT ME!

baseName - DOCUMENT ME!

componentName - DOCUMENT ME!

Returns:

DOCUMENT ME!