XJep (Java Expression Parser 2.4.2 API)

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

Fields
Modifier and Type	Field and Description
`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

Constructors
Modifier	Constructor and Description
	`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

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`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.
`Object`	`calcVarValue(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.
`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.
`Vector`	`getVarsInEquation(Node n, 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, 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, PrintStream out)` Prints the expression tree on given stream with newline at end.
`Vector`	`recursiveGetVarsInEquation(Node n, 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(Reader reader)` Restarts the parser with the given Reader.
`void`	`restartParser(String str)` Restarts the parser with the given string.
`Node`	`simplify(Node node)` Returns a simplification of an expression tree.
`Node`	`substitute(Node orig, String[] names, Node[] replacements)` Substitute all occurrences of a set of named variable with a set of expression tree.
`Node`	`substitute(Node orig, String name, Node replacement)` Substitute all occurrences of a named variable with an expression tree.
`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,
                       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,
                       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,
                  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,
                    PrintStream out)
```
    Prints the expression tree on given stream with newline at end.
  - toString
```
public 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 Object calcVarValue(String name)
                    throws 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:
    
    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(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(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 Vector getVarsInEquation(Node n,
                                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 Vector recursiveGetVarsInEquation(Node n,
                                         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 Object evaluate(PostfixMathCommandI pfmc,
                       Node node)
                throws ParseException
```
    Throws:
    
    ParseException

Class XJep

Field Summary

Fields inherited from class org.nfunk.jep.JEP

Constructor Summary

Method Summary

Methods inherited from class org.nfunk.jep.JEP

Methods inherited from class java.lang.Object

Field Detail

nf

tu

copier

subv

simpv

commandv

pv

Constructor Detail

XJep

XJep

XJep

Method Detail

newInstance

newInstance

addStandardFunctions

addStandardConstants

addComplex

deepCopy

simplify

preprocess

substitute

substitute

print

print

println

println

toString

getNodeFactory

getTreeUtils

getPrintVisitor

calcVarValue

continueParsing

restartParser

restartParser

getVarsInEquation

recursiveGetVarsInEquation

evaluate