visad.formula
Class FormulaManager

java.lang.Object
  visad.formula.FormulaManager

public class FormulaManager

extends Object

The FormulaManager class is the gateway into the visad.formula package, a general-purpose formula parser and evaluator. Variables update automatically when the variables upon which they depend change. For an example of usage, see the FormulaUtil.createStandardManager() method.

Field Summary

(package private) Method[]	bMethods binary method signatures
(package private) String[]	bOps binary operators
(package private) int[]	bPrec binary operator precedences
(package private) Method[]	fMethods function method signatures
(package private) String[]	funcs function names
(package private) Method[]	iMethods implicit function methods
(package private) int	iPrec implicit function precedence
(package private) Method	ppMethod formula text pre-parsing method.
(package private) Method[]	uMethods unary method signatures
(package private) String[]	uOps unary operators
(package private) int[]	uPrec unary operator precedences

Constructor Summary

FormulaManager(String[] binOps, int[] binPrec, String[] binMethods, String[] unaryOps, int[] unaryPrec, String[] unaryMethods, String[] functions, String[] funcMethods, int implicitPrec, String[] implicitMethods, String preParseMethod)
construct a new FormulaManager object

Method Summary

void	assignFormula(String name, String formula) assign a formula to a variable
boolean	canBeRemoved(String name) check whether it is safe to remove a variable from the database
void	createVar(String name, ThingReference tr) add a variable to the database that uses tr as its ThingReference
boolean	exists(String name) check whether a given variable is currently in the database
(package private) int	getBinaryPrec(String op) returns a binary operator's level of precedence
String[]	getErrors(String name) get the current list of errors that occurred when evaluating "name" and clear the list
String	getFormula(String name) get a variable's current formula
ThingReference	getReference(String name) get a variable's associated ThingReference
Thing	getThing(String name) get a variable's current value
(package private) int	getUnaryPrec(String op) returns a unary operator's level of precedence
(package private) FormulaVar	getVarByName(String name) return the variable "name"
(package private) FormulaVar	getVarByNameOrCreate(String name) return the variable "name", creating it if necessary
(package private) boolean	isBinaryOp(String op) identify whether a given token is a binary operator
(package private) boolean	isFunction(String token) identify whether a given token is a defined function
(package private) boolean	isUnaryOp(String op) identify whether a given token is a unary operator
void	remove(String name) remove a variable from the database
void	setReference(String name, ThingReference tr) set a variable's ThingReference
void	setTextRef(String name, ThingReference textRef) set a variable to auto-update its formula based on a Text object referenced by a ThingReference (useful for remote formula updates)
void	setThing(String name, Thing t) set a variable's value directly
void	waitForFormula(String name) blocks until this variable's formula is finished computing

Methods inherited from class java.lang.Object

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

Field Detail

bOps

String[] bOps

binary operators

bPrec

int[] bPrec

binary operator precedences

bMethods

Method[] bMethods

binary method signatures

uOps

String[] uOps

unary operators

uPrec

int[] uPrec

unary operator precedences

uMethods

Method[] uMethods

unary method signatures

funcs

String[] funcs

function names

fMethods

Method[] fMethods

function method signatures

iPrec

int iPrec

implicit function precedence

iMethods

Method[] iMethods

implicit function methods

ppMethod

Method ppMethod

formula text pre-parsing method. For an application to support unusual non-standard syntaxes, such as brackets (e.g., VAR[0]), that application should supply a "pre-parsing" method in the preParseMethod argument, which converts non-standard syntax to standard syntax (e.g., VAR[0] could become getElement(VAR, 0)). The supplied method should be a static method taking a String argument (the formula) and a FormulaManager argument (this FormulaManager). If the application does not need such functionality, the preParseMethod argument can be null.

Constructor Detail

FormulaManager

public FormulaManager(String[] binOps,
                      int[] binPrec,
                      String[] binMethods,
                      String[] unaryOps,
                      int[] unaryPrec,
                      String[] unaryMethods,
                      String[] functions,
                      String[] funcMethods,
                      int implicitPrec,
                      String[] implicitMethods,
                      String preParseMethod)
               throws FormulaException

construct a new FormulaManager object

Method Detail

createVar

public void createVar(String name,
                      ThingReference tr)
               throws VisADException

add a variable to the database that uses tr as its ThingReference

Throws:

VisADException

assignFormula

public void assignFormula(String name,
                          String formula)
                   throws VisADException

assign a formula to a variable

Throws:

VisADException

waitForFormula

public void waitForFormula(String name)
                    throws VisADException

blocks until this variable's formula is finished computing

Throws:

VisADException

setTextRef

public void setTextRef(String name,
                       ThingReference textRef)
                throws VisADException,
                       RemoteException

set a variable to auto-update its formula based on a Text object referenced by a ThingReference (useful for remote formula updates)

Throws:

VisADException

RemoteException

getErrors

public String[] getErrors(String name)

get the current list of errors that occurred when evaluating "name" and clear the list

canBeRemoved

public boolean canBeRemoved(String name)
                     throws FormulaException

check whether it is safe to remove a variable from the database

Throws:

FormulaException

exists

public boolean exists(String name)

check whether a given variable is currently in the database

remove

public void remove(String name)
            throws FormulaException

remove a variable from the database

Throws:

FormulaException

setThing

public void setThing(String name,
                     Thing t)
              throws VisADException,
                     RemoteException

set a variable's value directly

Throws:

VisADException

RemoteException

setReference

public void setReference(String name,
                         ThingReference tr)
                  throws VisADException

set a variable's ThingReference

Throws:

VisADException

getThing

public Thing getThing(String name)
               throws FormulaException

get a variable's current value

Throws:

FormulaException

getReference

public ThingReference getReference(String name)
                            throws FormulaException

get a variable's associated ThingReference

Throws:

FormulaException

getFormula

public String getFormula(String name)
                  throws FormulaException

get a variable's current formula

Throws:

FormulaException

getVarByName

FormulaVar getVarByName(String name)
                  throws FormulaException

return the variable "name"

Throws:

FormulaException

getVarByNameOrCreate

FormulaVar getVarByNameOrCreate(String name)
                          throws VisADException

return the variable "name", creating it if necessary

Throws:

VisADException

isUnaryOp

boolean isUnaryOp(String op)

identify whether a given token is a unary operator

isBinaryOp

boolean isBinaryOp(String op)

identify whether a given token is a binary operator

isFunction

boolean isFunction(String token)

identify whether a given token is a defined function

getUnaryPrec

int getUnaryPrec(String op)

returns a unary operator's level of precedence

getBinaryPrec

int getBinaryPrec(String op)

returns a binary operator's level of precedence