org.lsmp.djep.xjep
Class XJep

java.lang.Object
  org.nfunk.jep.JEP
      org.lsmp.djep.xjep.XJep

Direct Known Subclasses:

DJep

public class XJep
extends JEP

An extended version of JEP adds various routines for working with trees. Has a NodeFactory, and OperatorSet, TreeUtils and Visitors DoNothingVisitor,

Author:

Rich Morris Created on 16-Nov-2003

Field Summary

protected CommandVisitor	commandv
protected DeepCopyVisitor	copier
protected NodeFactory	nf Creates new nodes
protected PrintVisitor	pv
protected SimplificationVisitor	simpv
protected SubstitutionVisitor	subv
protected TreeUtils	tu A few utility functions.

Fields inherited from class org.nfunk.jep.JEP

allowAssignment, allowUndeclared, errorList, ev, funTab, implicitMul, numberFactory, opSet, parser, symTab

Constructor Summary

	XJep() Create a new XJep will all the function of JEP plus printing and other features.
	XJep(JEP j) Conversion constructor.
protected	XJep(XJep j) Copy constructions, reuses all the components of argument.

Method Summary

void	addComplex() Call this function if you want to parse expressions which involve complex numbers.
void	addStandardConstants() Adds the constants pi and e to the parser.
void	addStandardFunctions() Adds the standard functions to the parser.
java.lang.Object	calcVarValue(java.lang.String name) Calculates the value for the variables equation and returns that value.
Node	continueParsing() Continue parsing without re-initilising the stream.
Node	deepCopy(Node node) Returns a deep copy of an expression tree.
java.lang.Object	evaluate(PostfixMathCommandI pfmc, Node node)
NodeFactory	getNodeFactory() Returns the node factory, used for constructing trees of Nodes.
PrintVisitor	getPrintVisitor() Returns the PrintVisitor, used for printing equations.
TreeUtils	getTreeUtils() Returns the TreeUtilitities, used for examining properties of nodes.
java.util.Vector	getVarsInEquation(Node n, java.util.Vector v) Finds all the variables in an equation.
XJep	newInstance() Creates a new instance of XJep with the same components as this one.
XJep	newInstance(SymbolTable st) Creates a new instance of XJep with the same components as this one and the specified symbol table.
Node	preprocess(Node node) Pre-processes an equation to allow the diff and eval operators to be used.
void	print(Node node) Prints the expression tree on standard output.
void	print(Node node, java.io.PrintStream out) Prints the expression tree on given stream.
void	println(Node node) Prints the expression tree on standard output with newline at end.
void	println(Node node, java.io.PrintStream out) Prints the expression tree on given stream with newline at end.
java.util.Vector	recursiveGetVarsInEquation(Node n, java.util.Vector v) Finds all the variables in an equation and if any of those variables are defined by equations find the variables in those equations as well.
void	restartParser(java.io.Reader reader) Restarts the parser with the given Reader.
void	restartParser(java.lang.String str) Restarts the parser with the given string.
Node	simplify(Node node) Returns a simplification of an expression tree.
Node	substitute(Node orig, java.lang.String[] names, Node[] replacements) Substitute all occurrences of a set of named variable with a set of expression tree.
Node	substitute(Node orig, java.lang.String name, Node replacement) Substitute all occurrences of a named variable with an expression tree.
java.lang.String	toString(Node node) Returns a string representation of a expression tree.

Methods inherited from class org.nfunk.jep.JEP

addConstant, addFunction, addVariable, addVariable, addVariable, evaluate, getAllowAssignment, getAllowUndeclared, getComplexValue, getErrorInfo, getEvaluatorVisitor, getFunctionTable, getImplicitMul, getNumberFactory, getOperatorSet, getParser, getSymbolTable, getTopNode, getTraverse, getValue, getValueAsObject, getVar, getVarValue, hasError, initFunTab, initSymTab, parse, parseExpression, removeFunction, removeVariable, setAllowAssignment, setAllowUndeclared, setImplicitMul, setTraverse, setVarValue

Methods inherited from class java.lang.Object

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

Field Detail

nf

protected NodeFactory nf

Creates new nodes

tu

protected TreeUtils tu

A few utility functions.

copier

protected DeepCopyVisitor copier

subv

protected SubstitutionVisitor subv

simpv

protected SimplificationVisitor simpv

commandv

protected CommandVisitor commandv

pv

protected PrintVisitor pv

Constructor Detail

XJep

public XJep()

Create a new XJep will all the function of JEP plus printing and other features.

XJep

protected XJep(XJep j)

Copy constructions, reuses all the components of argument.

XJep

public XJep(JEP j)

Conversion constructor. Turns a JEP object into an XJep object.

Parameters:

j -

Method Detail

newInstance

public XJep newInstance()

Creates a new instance of XJep with the same components as this one. Sub classes should overwrite this method to create objects of the correct type.

newInstance

public XJep newInstance(SymbolTable st)

Creates a new instance of XJep with the same components as this one and the specified symbol table. Sub classes should overwrite this method to create objects of the correct type.

addStandardFunctions

public void addStandardFunctions()

Description copied from class: JEP

Adds the standard functions to the parser. If this function is not called before parsing an expression, functions such as sin() or cos() would produce an "Unrecognized function..." error. In most cases, this method should be called immediately after the JEP object is created.

Overrides:

addStandardFunctions in class JEP

addStandardConstants

public void addStandardConstants()

Description copied from class: JEP

Adds the constants pi and e to the parser. As addStandardFunctions(), this method should be called immediately after the JEP object is created.

Overrides:

addStandardConstants in class JEP

addComplex

public void addComplex()

Description copied from class: JEP

Call this function if you want to parse expressions which involve complex numbers. This method specifies "i" as the imaginary unit (0,1). Two functions re() and im() are also added for extracting the real or imaginary components of a complex number respectively.

Overrides:

addComplex in class JEP

deepCopy

public Node deepCopy(Node node)
              throws ParseException

Returns a deep copy of an expression tree.

Throws:

ParseException

simplify

public Node simplify(Node node)
              throws ParseException

Returns a simplification of an expression tree.

Throws:

ParseException

preprocess

public Node preprocess(Node node)
                throws ParseException

Pre-processes an equation to allow the diff and eval operators to be used.

Throws:

ParseException

substitute

public Node substitute(Node orig,
                       java.lang.String name,
                       Node replacement)
                throws ParseException

Substitute all occurrences of a named variable with an expression tree.

Throws:

ParseException

substitute

public Node substitute(Node orig,
                       java.lang.String[] names,
                       Node[] replacements)
                throws ParseException

Substitute all occurrences of a set of named variable with a set of expression tree.

Throws:

ParseException

print

public void print(Node node)

Prints the expression tree on standard output.

print

public void print(Node node,
                  java.io.PrintStream out)

Prints the expression tree on given stream.

println

public void println(Node node)

Prints the expression tree on standard output with newline at end.

println

public void println(Node node,
                    java.io.PrintStream out)

Prints the expression tree on given stream with newline at end.

toString

public java.lang.String toString(Node node)

Returns a string representation of a expression tree.

getNodeFactory

public NodeFactory getNodeFactory()

Returns the node factory, used for constructing trees of Nodes.

getTreeUtils

public TreeUtils getTreeUtils()

Returns the TreeUtilitities, used for examining properties of nodes.

getPrintVisitor

public PrintVisitor getPrintVisitor()

Returns the PrintVisitor, used for printing equations.

calcVarValue

public java.lang.Object calcVarValue(java.lang.String name)
                              throws java.lang.Exception

Calculates the value for the variables equation and returns that value. If the variable does not have an equation just return its value.

Throws:

java.lang.Exception

continueParsing

public Node continueParsing()
                     throws ParseException

Continue parsing without re-initilising the stream. Allows re-entrance of parser so that strings like "x=1; y=2; z=3;" can be parsed. When a semi colon is encountered parsing finishes leaving the rest of the string unparsed. Parsing can be resumed from the current position by using this method. For example

 XJep j = new XJep();
 j.restartParser("x=1;y=2; z=3;");
 Node node;
 try {
 while((node = j.continueParsing())!=null) {
    j.println(node);
 } }catch(ParseException e) {}
 

Returns:

top node of equation parsed to date or null if empty equation

Throws:

ParseException

See Also:

restartParser(String)

restartParser

public void restartParser(java.lang.String str)

Restarts the parser with the given string.

Parameters:

str - String containing a sequence of equations separated by semi-colons.

See Also:

continueParsing()

restartParser

public void restartParser(java.io.Reader reader)

Restarts the parser with the given Reader.

Parameters:

reader - Reader from which equations separated by semi-colons will be read.

See Also:

continueParsing()

getVarsInEquation

public java.util.Vector getVarsInEquation(Node n,
                                          java.util.Vector v)

Finds all the variables in an equation.

Parameters:

n - the top node of the expression

v - a vector to store the list of variables (new variables will be added on end)

Returns:

v

recursiveGetVarsInEquation

public java.util.Vector recursiveGetVarsInEquation(Node n,
                                                   java.util.Vector v)
                                            throws ParseException

Finds all the variables in an equation and if any of those variables are defined by equations find the variables in those equations as well. The result is an ordered sequence, evaluating each variable in turn will correctly allow the final equation to be evaluated.

For example if the equation is a+b and a=c+d, b=c+e then the result will be the sequence (c,d,a,e,b)

Parameters:

n - top node

v - vector for storing results, new variables will be added on the end.

Returns:

v, the ordered sequence of variables

Throws:

ParseException - if equation is recursive i.e. x=y; y=x+1;

evaluate

public java.lang.Object evaluate(PostfixMathCommandI pfmc,
                                 Node node)
                          throws ParseException

Throws:

ParseException