edu.buffalo.fs7.mathlib
Class Parse

java.lang.Object
  |
  +--edu.buffalo.fs7.mathlib.Parse

public class Parse

extends java.lang.Object

class providing methods to parse an arithmetic expression. A string with an arithmetic expression is first preprocessed to allow certain short notations such like |01><01| for an outer product, then then string is divided into MathObject tokens by the Tokenizer class. The parse class finally evaluates the expression and returns the result of the expression or throws an exception in case of an error.

Since this class is the central class for evalutating an expression it also provides the mathlib event handling. Everytime there is for example an assignment in an expression and the expression was completely evaluated, a MathlibEvent is fired to notify listeners about the newly assigned variable. The MathlibEvent mechnism is very similar to the event model implemented in Java itself. Potential listener classes need to implement the MathlibEventListener interface and register themselves here in the Parse object.

For this class to have all features, a Mathlib object must be instantiated. Although this class provides static expression evalutation methods, it is strongly recommended to provide a mathlib object in order to use the full functinality (the Mathlib class provides the variable management).

MathlibEvent listeners are for example the classes Mathlib, QVarTree, GateTable.

See Also:

Tokenizer, Mathlib, MathlibEvent, MathlibEventListener

Field Summary

protected static java.lang.String	category
static boolean	echoAnswer still in use ?
protected static java.util.Vector	listeners holds the MathlibEventListeners
protected Mathlib	mathlib holds the Mathlib object

Constructor Summary

Parse(Mathlib mathlib)
creates a Parse object associated with a certain Mathlib object

Method Summary

static void	addMathlibEventListener(MathlibEventListener m) registers a MathlibEventListener
java.lang.String	evaluateExpression(java.lang.String str) this method fully evaluates an expression and assignes the result variable.
static void	fireMathlibEvent(java.lang.String objectName, MathObject mathObject, int action) creates a MathlibEvent and pumps it to processEvent
static void	fireMathlibEvent(java.lang.String objectName, java.lang.String newName) creates a MathlibEvent and pumps it to processEvent
static void	fireMathlibEvent(java.lang.String objectName, java.lang.String newName, java.lang.String category, MathObject mathObject, int action) creates a MathlibEvent and pumps it to processEvent
static MathObject	parseExpression(java.lang.String str) static method which can parse an expression without using variable and without any assignments.
protected static void	processEvent(MathlibEvent event) is called internally by fireMathlibEvent in order to dispatch the event
static void	removeMathlibEventListener(MathlibEventListener m) removes a MathlibEventListener
static java.lang.String	replaceSubstring(java.lang.String workStr, java.lang.String oldStr, java.lang.String newStr) static method replacing a substring by another substring used by the preprocessor
void	setCategory(java.lang.String newCategory) set a preset category in order to let all MathlibEvents generated by the parse methods belong to this preset category (not used anymore)

Methods inherited from class java.lang.Object

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

Field Detail

echoAnswer

public static boolean echoAnswer

still in use ?

listeners

protected static java.util.Vector listeners

holds the MathlibEventListeners

mathlib

protected Mathlib mathlib

holds the Mathlib object

category

protected static java.lang.String category

Constructor Detail

Parse

public Parse(Mathlib mathlib)

creates a Parse object associated with a certain Mathlib object

Method Detail

addMathlibEventListener

public static void addMathlibEventListener(MathlibEventListener m)

registers a MathlibEventListener

Parameters:

m - listener object

removeMathlibEventListener

public static void removeMathlibEventListener(MathlibEventListener m)

removes a MathlibEventListener

processEvent

protected static void processEvent(MathlibEvent event)

is called internally by fireMathlibEvent in order to dispatch the event

Parameters:

e - MathlibEvent to dispatch

fireMathlibEvent

public static void fireMathlibEvent(java.lang.String objectName,
                                    MathObject mathObject,
                                    int action)

creates a MathlibEvent and pumps it to processEvent

Parameters:

objectName - name of the mathobject

mathObject - the actual mathobject

the - action to perform

fireMathlibEvent

public static void fireMathlibEvent(java.lang.String objectName,
                                    java.lang.String newName,
                                    java.lang.String category,
                                    MathObject mathObject,
                                    int action)

creates a MathlibEvent and pumps it to processEvent

Parameters:

objectName - name of the mathobject

newName - new name of the mathobject in case of a CHANGE_NAM event

category - logical category of the mathobject

mathObject - the actual mathobject

the - action to perform

fireMathlibEvent

public static void fireMathlibEvent(java.lang.String objectName,
                                    java.lang.String newName)

creates a MathlibEvent and pumps it to processEvent

Parameters:

objectName - name of the mathobject

newName - new name of the mathobject

the - action to perform

setCategory

public void setCategory(java.lang.String newCategory)

set a preset category in order to let all MathlibEvents generated by the parse methods belong to this preset category (not used anymore)

parseExpression

public static MathObject parseExpression(java.lang.String str)
                                  throws java.lang.IllegalArgumentException

static method which can parse an expression without using variable and without any assignments.

Parameters:

str - string to parse

Returns:

the mathobject which was identified

evaluateExpression

public java.lang.String evaluateExpression(java.lang.String str)
                                    throws java.lang.IllegalArgumentException

this method fully evaluates an expression and assignes the result variable. If you just want to evaluate an algebraic expression without assigning the result variable use parseExpression

Parameters:

str - string to be evaluated

See Also:

.

replaceSubstring

public static java.lang.String replaceSubstring(java.lang.String workStr,
                                                java.lang.String oldStr,
                                                java.lang.String newStr)

static method replacing a substring by another substring used by the preprocessor

Parameters:

workStr - string to work in

oldStr - substring to replace

newStr - string to replace with