com.ff.JEvaluator
Class JEvaluator

java.lang.Object
  com.ff.JEvaluator.JEvaluator

public class JEvaluator
extends java.lang.Object

Author:

fiorucci

Field Summary

private java.util.HashMap<java.lang.String,JEvaluatorNodeBaseClass>	evaluatorExprs
private java.util.HashMap<java.lang.String,BaseFunctionInterface>	evaluatorFuncs
private java.util.HashMap<java.lang.String,java.lang.String>	evaluatorNames
protected static org.apache.commons.logging.Log	log

Constructor Summary

JEvaluator()

JEvaluator(java.lang.String varEqualsExpr)
Creates an evaluator from an expression such as "varName=expr"

JEvaluator(java.lang.String varName, java.lang.String expr)

Method Summary

protected java.util.List<java.lang.String>	buildParamList(JEvaluatorNodeFunc f) Computes function parameter values and builds list of "double" values to be later passed to the compute() method of the selected function
protected java.lang.String	compute(JEvaluatorNodeBaseClass n) Recursively computes a subtree starting from the given rootNode
private java.lang.String	computeFunction(JEvaluatorNodeBaseClass n)
boolean	delVar(java.lang.String varName) Deletes a variable for the current evaluator instance
void	dump(java.lang.String varName)
private void	exprCharDump(JEvaluatorExprChar[] exprChars, int startPosition, int endPosition)
private java.lang.String	getExpressionRecursive(JEvaluatorNodeBaseClass n) Recursively traverses this evaluator instance's tree, rebuilding the mathematical expression string for later printout
java.lang.String	getVar(java.lang.String varName) Gets a variable's value for the current evaluator instance
boolean	init(java.lang.String configFile)
protected BaseFunctionInterface	initFunctionClass(java.lang.String fName) Instantiates a BaseFunctionInterface for later computation, based on the function's name
boolean	isFunctionRegistered(BaseFunctionInterface f) Checks to see whether a function was registered
boolean	isFunctionRegistered(java.lang.String functionName) Checks to see whether a function was registered
boolean	isVarDefined(java.lang.String varName) Checks to see whether varName is defined for the current evaluator instance
private JEvaluatorNodeBaseClass	parse(java.lang.String expression) Parses the specified mathematical expression
private void	recursiveDumper(JEvaluatorNodeBaseClass n)
private JEvaluatorNodeBaseClass	recursiveParser(JEvaluatorExprChar[] exprChars, int startPosition, int endPosition) Recursively parses the specified mathematical expression
void	registerFunction(BaseFunctionInterface f) Registers a customized function to JEvaluator
boolean	setExpr(java.lang.String expression) Sets a variable's value for the current evaluator instance, based on an expression in the format "varName=expression"
boolean	setVar(java.lang.String varName, java.lang.String expr) Sets a variable's value for the current evaluator instance
void	unregisterFunction(BaseFunctionInterface f) Unregisters a customized function to JEvaluator
boolean	unregisterFunction(java.lang.String functionName) Unregisters a customized function to JEvaluator

Methods inherited from class java.lang.Object

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

Field Detail

log

protected static org.apache.commons.logging.Log log

evaluatorNames

private java.util.HashMap<java.lang.String,java.lang.String> evaluatorNames

evaluatorExprs

private java.util.HashMap<java.lang.String,JEvaluatorNodeBaseClass> evaluatorExprs

evaluatorFuncs

private java.util.HashMap<java.lang.String,BaseFunctionInterface> evaluatorFuncs

Constructor Detail

JEvaluator

public JEvaluator()

JEvaluator

public JEvaluator(java.lang.String varName,
                  java.lang.String expr)

JEvaluator

public JEvaluator(java.lang.String varEqualsExpr)

Creates an evaluator from an expression such as "varName=expr"

Parameters:

varEqualsExpr -

Method Detail

init

public boolean init(java.lang.String configFile)

recursiveDumper

private void recursiveDumper(JEvaluatorNodeBaseClass n)

dump

public void dump(java.lang.String varName)

exprCharDump

private void exprCharDump(JEvaluatorExprChar[] exprChars,
                          int startPosition,
                          int endPosition)

recursiveParser

private JEvaluatorNodeBaseClass recursiveParser(JEvaluatorExprChar[] exprChars,
                                                int startPosition,
                                                int endPosition)

Recursively parses the specified mathematical expression

Parameters:

exprChars - An evaluatorExprChar array

startPosition - The leftmost evaluatorExprChar array element to consider

endPosition - The number of items in the array

Returns:

an evaluatorNode

parse

private JEvaluatorNodeBaseClass parse(java.lang.String expression)

Parses the specified mathematical expression

Parameters:

expression - The expression to be parsed

Returns:

an EvaluatorNode if parsing was successful, null if expression has unbalanced parenthesis

getExpressionRecursive

private java.lang.String getExpressionRecursive(JEvaluatorNodeBaseClass n)

Recursively traverses this evaluator instance's tree, rebuilding the mathematical expression string for later printout

Parameters:

n - the root node

Returns:

the expression string for this subtree

compute

protected java.lang.String compute(JEvaluatorNodeBaseClass n)
                            throws java.lang.Exception

Recursively computes a subtree starting from the given rootNode

Parameters:

n - the rootNode

Returns:

the subtree result

Throws:

java.lang.Exception

computeFunction

private java.lang.String computeFunction(JEvaluatorNodeBaseClass n)
                                  throws java.lang.Exception

Throws:

java.lang.Exception

initFunctionClass

protected BaseFunctionInterface initFunctionClass(java.lang.String fName)
                                           throws JEvaluatorException

Instantiates a BaseFunctionInterface for later computation, based on the function's name

Parameters:

fName - the function's name (sum, avg, ...)

Returns:

a BaseFunctionInterface instance, for later bfi.compute() call

Throws:

JEvaluatorException

buildParamList

protected java.util.List<java.lang.String> buildParamList(JEvaluatorNodeFunc f)
                                                   throws java.lang.Exception

Computes function parameter values and builds list of "double" values to be later passed to the compute() method of the selected function

Parameters:

f - the evaluator node function

Returns:

the list of Double parameters to be passed to the function

Throws:

java.lang.Exception

setExpr

public boolean setExpr(java.lang.String expression)

Sets a variable's value for the current evaluator instance, based on an expression in the format "varName=expression"

Parameters:

expression - the expression in the format "varName=expression"

Returns:

false if varName was newly created, false in case varName's previous value was overridden

setVar

public boolean setVar(java.lang.String varName,
                      java.lang.String expr)

Sets a variable's value for the current evaluator instance

Parameters:

varName - the variable's name

expr - the value/expression to set

Returns:

false if varName was newly created, false in case varName's previous value was overridden

getVar

public java.lang.String getVar(java.lang.String varName)
                        throws java.lang.Exception

Gets a variable's value for the current evaluator instance

Parameters:

varName - the variable name

Returns:

the variable value

Throws:

java.lang.Exception

delVar

public boolean delVar(java.lang.String varName)

Deletes a variable for the current evaluator instance

Parameters:

varName - the variable name

Returns:

true if deletion was successful, false otherwise (variable not found)

isVarDefined

public boolean isVarDefined(java.lang.String varName)

Checks to see whether varName is defined for the current evaluator instance

Parameters:

varName - the variable's name

Returns:

true is varName is defined, false otherwise

registerFunction

public void registerFunction(BaseFunctionInterface f)

Registers a customized function to JEvaluator

Parameters:

f - the Function object to register

unregisterFunction

public void unregisterFunction(BaseFunctionInterface f)

Unregisters a customized function to JEvaluator

Parameters:

f - the Function object to unregister

unregisterFunction

public boolean unregisterFunction(java.lang.String functionName)

Unregisters a customized function to JEvaluator

Parameters:

functionName - the Function object to unregister

Returns:

true if unregistration was successful, false otherwise

isFunctionRegistered

public boolean isFunctionRegistered(BaseFunctionInterface f)

Checks to see whether a function was registered

Parameters:

f - the function object

Returns:

true if function was registered, false otherwise

isFunctionRegistered

public boolean isFunctionRegistered(java.lang.String functionName)

Checks to see whether a function was registered

Parameters:

functionName - the function name

Returns:

true if function was registered, false otherwise