JEP (Java Expression Parser 2.4.2 API)

java.lang.Object
- org.nfunk.jep.JEP

Direct Known Subclasses:

GroupJep, VectorJep, XJep
```
public class JEP
extends Object
```
The JEP class is the main interface with which the user should interact. It contains all necessary methods to parse and evaluate expressions.
The most important methods are parseExpression(String), for parsing the mathematical expression, and getValue() for obtaining the value of the expression.
Visit http://www.singularsys.com/jep for the newest version of JEP, and complete documentation.

Since:

04/02/13 added Binom function

Author:

Nathan Funk

Field Summary

Fields
Modifier and Type	Field and Description
`protected boolean`	`allowAssignment` Allow undeclared variables option
`protected boolean`	`allowUndeclared` Allow undeclared variables option
`protected Vector`	`errorList` Error List
`protected EvaluatorVisitor`	`ev` Evaluator
`protected FunctionTable`	`funTab` Function Table
`protected boolean`	`implicitMul` Implicit multiplication option
`protected NumberFactory`	`numberFactory` Number factory
`protected OperatorSet`	`opSet` OperatorSet
`protected Parser`	`parser` The parser object
`protected SymbolTable`	`symTab` Symbol Table

Constructor Summary

Constructors
Modifier	Constructor and Description
	`JEP()` Creates a new JEP instance with the default settings.
	`JEP(boolean traverse_in, boolean allowUndeclared_in, boolean implicitMul_in, NumberFactory numberFactory_in)` Creates a new JEP instance with custom settings.
`protected`	`JEP(JEP j)` This constructor copies the SymbolTable and other components of the arguments to the new instance.

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`	`addConstant(String name, Object value)` Adds a constant.
`void`	`addFunction(String functionName, PostfixMathCommandI function)` Adds a new function to the parser.
`void`	`addStandardConstants()` Adds the constants pi and e to the parser.
`void`	`addStandardFunctions()` Adds the standard functions to the parser.
`Double`	`addVariable(String name, double value)` Adds a new variable to the parser, or updates the value of an existing variable.
`Complex`	`addVariable(String name, double re, double im)` Adds a new complex variable to the parser, or updates the value of an existing variable.
`void`	`addVariable(String name, Object object)` Adds a new variable to the parser as an object, or updates the value of an existing variable.
`Object`	`evaluate(Node node)` Evaluate an expression.
`boolean`	`getAllowAssignment()` Whether assignment equation `y=x+1` equations are allowed.
`boolean`	`getAllowUndeclared()` Returns the value of the allowUndeclared option.
`Complex`	`getComplexValue()` Evaluates and returns the value of the expression as a complex number.
`String`	`getErrorInfo()` Reports information on the errors that occurred during the most recent action.
`EvaluatorVisitor`	`getEvaluatorVisitor()` Returns the EvaluatorVisitor
`FunctionTable`	`getFunctionTable()` Returns the function table (the list of all functions that the parser recognizes).
`boolean`	`getImplicitMul()` Returns the value of the implicit multiplication option.
`NumberFactory`	`getNumberFactory()` Returns the number factory.
`OperatorSet`	`getOperatorSet()` Returns the operator set.
`Parser`	`getParser()` Returns the parse object.
`SymbolTable`	`getSymbolTable()` Returns the symbol table (the list of all variables that the parser recognizes).
`Node`	`getTopNode()` Returns the top node of the expression tree.
`boolean`	`getTraverse()` Returns the value of the traverse option.
`double`	`getValue()` Evaluates and returns the value of the expression as a double number.
`Object`	`getValueAsObject()` Evaluates and returns the value of the expression as an object.
`Variable`	`getVar(String name)` Gets the object representing the variable with a given name.
`Object`	`getVarValue(String name)` Returns the value of the variable with given name.
`boolean`	`hasError()` Returns true if an error occurred during the most recent action (parsing or evaluation).
`void`	`initFunTab()` Creates a new FunctionTable object as funTab.
`void`	`initSymTab()` Creates a new SymbolTable object as symTab.
`Node`	`parse(String expression)` Parses an expression.
`Node`	`parseExpression(String expression_in)` Parses the expression.
`Object`	`removeFunction(String name)` Removes a function from the parser.
`Object`	`removeVariable(String name)` Removes a variable from the parser.
`void`	`setAllowAssignment(boolean value)` Sets whether assignment equations like `y=x+1` are allowed.
`void`	`setAllowUndeclared(boolean value)` Sets the value for the undeclared variables option.
`void`	`setImplicitMul(boolean value)` Sets the value of the implicit multiplication option.
`void`	`setTraverse(boolean value)` Sets the value of the traverse option.
`void`	`setVarValue(String name, Object val)` Sets the value of a variable.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - allowUndeclared
```
protected boolean allowUndeclared
```
    Allow undeclared variables option
  - allowAssignment
```
protected boolean allowAssignment
```
    Allow undeclared variables option
  - implicitMul
```
protected boolean implicitMul
```
    Implicit multiplication option
  - symTab
```
protected SymbolTable symTab
```
    Symbol Table
  - funTab
```
protected FunctionTable funTab
```
    Function Table
  - errorList
```
protected Vector errorList
```
    Error List
  - parser
```
protected Parser parser
```
    The parser object
  - ev
```
protected EvaluatorVisitor ev
```
    Evaluator
  - numberFactory
```
protected NumberFactory numberFactory
```
    Number factory
  - opSet
```
protected OperatorSet opSet
```
    OperatorSet
- Constructor Detail
  - JEP
```
public JEP()
```
    Creates a new JEP instance with the default settings.
    Traverse = false
    Allow undeclared variables = false
    Implicit multiplication = false
    Number Factory = DoubleNumberFactory
  - JEP
```
public JEP(boolean traverse_in,
           boolean allowUndeclared_in,
           boolean implicitMul_in,
           NumberFactory numberFactory_in)
```
    Creates a new JEP instance with custom settings. If the numberFactory_in is null, the default number factory is used.
    
    Parameters:
    
    traverse_in - The traverse option.
    
    allowUndeclared_in - The "allow undeclared variables" option.
    
    implicitMul_in - The implicit multiplication option.
    
    numberFactory_in - The number factory to be used.
  - JEP
```
protected JEP(JEP j)
```
    This constructor copies the SymbolTable and other components of the arguments to the new instance. Subclasses can call this protected constructor and set the individual components themselves.
    
    Since:
    
    2.3.0 alpha
- Method Detail
  - initSymTab
```
public void initSymTab()
```
    Creates a new SymbolTable object as symTab.
  - initFunTab
```
public void initFunTab()
```
    Creates a new FunctionTable object as funTab.
  - addStandardFunctions
```
public void addStandardFunctions()
```
    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.
    
    Since:
    
    2.3.0 alpha added if and exp functions, 2.3.0 beta 1 added str function
  - addStandardConstants
```
public void addStandardConstants()
```
    Adds the constants pi and e to the parser. As addStandardFunctions(), this method should be called immediately after the JEP object is created.
  - addComplex
```
public void addComplex()
```
    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.
    
    Since:
    
    2.3.0 alpha The functions cmod and arg are added to get the modulus and argument., 2.3.0 beta 1 The functions complex and polar to convert x,y and r,theta to Complex., Feb 05 added complex conjugate conj.
  - addFunction
```
public void addFunction(String functionName,
                        PostfixMathCommandI function)
```
    Adds a new function to the parser. This must be done before parsing an expression so the parser is aware that the new function may be contained in the expression.
    
    Parameters:
    
    functionName - The name of the function
    
    function - The function object that is used for evaluating the function
  - addConstant
```
public void addConstant(String name,
                        Object value)
```
    Adds a constant. This is a variable whose value cannot be changed.
    
    Since:
    
    2.3.0 beta 1
  - addVariable
```
public Double addVariable(String name,
                          double value)
```
    Adds a new variable to the parser, or updates the value of an existing variable. This must be done before parsing an expression so the parser is aware that the new variable may be contained in the expression.
    
    Parameters:
    
    name - Name of the variable to be added
    
    value - Initial value or new value for the variable
    
    Returns:
    
    Double object of the variable
  - addVariable
```
public Complex addVariable(String name,
                           double re,
                           double im)
```
    Adds a new complex variable to the parser, or updates the value of an existing variable. This must be done before parsing an expression so the parser is aware that the new variable may be contained in the expression.
    
    Parameters:
    
    name - Name of the variable to be added
    
    re - Initial real value or new real value for the variable
    
    im - Initial imaginary value or new imaginary value for the variable
    
    Returns:
    
    Complex object of the variable
  - addVariable
```
public void addVariable(String name,
                        Object object)
```
    Adds a new variable to the parser as an object, or updates the value of an existing variable. This must be done before parsing an expression so the parser is aware that the new variable may be contained in the expression.
    
    Parameters:
    
    name - Name of the variable to be added
    
    object - Initial value or new value for the variable
  - removeVariable
```
public Object removeVariable(String name)
```
    Removes a variable from the parser. For example after calling addStandardConstants(), removeVariable("e") might be called to remove the euler constant from the set of variables.
    
    Returns:
    
    The value of the variable if it was added earlier. If the variable is not in the table of variables, null is returned.
  - getVarValue
```
public Object getVarValue(String name)
```
    Returns the value of the variable with given name.
    
    Parameters:
    
    name - name of the variable.
    
    Returns:
    
    the current value of the variable.
    
    Since:
    
    2.3.0 alpha
  - setVarValue
```
public void setVarValue(String name,
                        Object val)
```
    Sets the value of a variable. The variable must exist before hand.
    
    Parameters:
    
    name - name of the variable.
    
    val - the initial value of the variable.
    
    Throws:
    
    NullPointerException - if the variable has not been previously created with addVariable(String,Object) first.
    
    Since:
    
    2.3.0 alpha, April 05 - throws an exception if variable unset.
  - getVar
```
public Variable getVar(String name)
```
    Gets the object representing the variable with a given name.
    
    Parameters:
    
    name - the name of the variable to find.
    
    Returns:
    
    the Variable object or null if name not found.
    
    Since:
    
    2.3.0 alpha
  - removeFunction
```
public Object removeFunction(String name)
```
    Removes a function from the parser.
    
    Returns:
    
    If the function was added earlier, the function class instance is returned. If the function was not present, null is returned.
  - setTraverse
```
public void setTraverse(boolean value)
```
    Sets the value of the traverse option. setTraverse is useful for debugging purposes. When traverse is set to true, the parse-tree will be dumped to the standard output device.
    The default value is false.
    
    Parameters:
    
    value - The boolean traversal option.
  - getTraverse
```
public boolean getTraverse()
```
    Returns the value of the traverse option.
    
    Returns:
    
    True if the traverse option is enabled. False otherwise.
  - setImplicitMul
```
public void setImplicitMul(boolean value)
```
    Sets the value of the implicit multiplication option. If this option is set to true before parsing, implicit multiplication will be allowed. That means that an expression such as
```
"1 2"
```
    is valid and is interpreted as
```
"1*2"
```
    .
    The default value is false.
    Parameters:
    
    value - The boolean implicit multiplication option.
  - getImplicitMul
```
public boolean getImplicitMul()
```
    Returns the value of the implicit multiplication option.
    
    Returns:
    
    True if the implicit multiplication option is enabled. False otherwise.
  - setAllowUndeclared
```
public void setAllowUndeclared(boolean value)
```
    Sets the value for the undeclared variables option. If this option is set to true, expressions containing variables that were not previously added to JEP will not produce an "Unrecognized Symbol" error. The new variables will automatically be added while parsing, and initialized to 0.
    If this option is set to false, variables that were not previously added to JEP will produce an error while parsing.
    The default value is false.
    
    Parameters:
    
    value - The boolean option for allowing undeclared variables.
  - getAllowUndeclared
```
public boolean getAllowUndeclared()
```
    Returns the value of the allowUndeclared option.
    
    Returns:
    
    True if the allowUndeclared option is enabled. False otherwise.
  - setAllowAssignment
```
public void setAllowAssignment(boolean value)
```
    Sets whether assignment equations like y=x+1 are allowed.
    
    Since:
    
    2.3.0 alpha
  - getAllowAssignment
```
public boolean getAllowAssignment()
```
    Whether assignment equation y=x+1 equations are allowed.
    
    Since:
    
    2.3.0 alpha
  - parseExpression
```
public Node parseExpression(String expression_in)
```
    Parses the expression. If there are errors in the expression, they are added to the errorList member. Errors can be obtained through getErrorInfo().
    
    Parameters:
    
    expression_in - The input expression string
    
    Returns:
    
    the top node of the expression tree if the parse was successful, null otherwise
  - parse
```
public Node parse(String expression)
           throws ParseException
```
    Parses an expression. Returns a object of type Node, does not catch errors. Does not set the topNode variable of the JEP instance. This method should generally be used with the evaluate method rather than getValueAsObject.
    
    Parameters:
    
    expression - represented as a string.
    
    Returns:
    
    The top node of a tree representing the parsed expression.
    
    Throws:
    
    ParseException
    
    Since:
    
    2.3.0 alpha, 2.3.0 beta - will raise exception if errorList non empty
  - evaluate
```
public Object evaluate(Node node)
                throws ParseException
```
    Evaluate an expression. This method evaluates the argument rather than the topNode of the JEP instance. It should be used in conjunction with parse rather than parseExpression.
    
    Parameters:
    
    node - the top node of the tree representing the expression.
    
    Returns:
    
    The value of the expression
    
    Throws:
    
    ParseException - if for some reason the expression could not be evaluated
    
    RuntimeException - could potentially be thrown.
    
    Since:
    
    2.3.0 alpha
  - getValue
```
public double getValue()
```
    Evaluates and returns the value of the expression as a double number.
    
    Returns:
    
    The calculated value of the expression as a double number. If the type of the value does not implement the Number interface (e.g. Complex), NaN is returned. If an error occurs during evaluation, NaN is returned and hasError() will return true.
    
    See Also:
    
    getComplexValue()
  - getComplexValue
```
public Complex getComplexValue()
```
    Evaluates and returns the value of the expression as a complex number.
    
    Returns:
    
    The calculated value of the expression as a complex number if no errors occur. Returns null otherwise.
  - getValueAsObject
```
public Object getValueAsObject()
```
    Evaluates and returns the value of the expression as an object. The EvaluatorVisitor member ev is used to do the evaluation procedure. This method is useful when the type of the value is unknown, or not important.
    
    Returns:
    
    The calculated value of the expression if no errors occur. Returns null otherwise.
  - hasError
```
public boolean hasError()
```
    Returns true if an error occurred during the most recent action (parsing or evaluation).
    
    Returns:
    
    Returns true if an error occurred during the most recent action (parsing or evaluation).
  - getErrorInfo
```
public String getErrorInfo()
```
    Reports information on the errors that occurred during the most recent action.
    
    Returns:
    
    A string containing information on the errors, each separated by a newline character; null if no error has occurred
  - getTopNode
```
public Node getTopNode()
```
    Returns the top node of the expression tree. Because all nodes are pointed to either directly or indirectly, the entire expression tree can be accessed through this node. It may be used to manipulate the expression, and subsequently evaluate it manually.
    
    Returns:
    
    The top node of the expression tree
  - getSymbolTable
```
public SymbolTable getSymbolTable()
```
    Returns the symbol table (the list of all variables that the parser recognizes).
    
    Returns:
    
    The symbol table
  - getFunctionTable
```
public FunctionTable getFunctionTable()
```
    Returns the function table (the list of all functions that the parser recognizes).
    
    Returns:
    
    The function table
  - getEvaluatorVisitor
```
public EvaluatorVisitor getEvaluatorVisitor()
```
    Returns the EvaluatorVisitor
    
    Returns:
    
    the EvaluatorVisitor.
  - getNumberFactory
```
public NumberFactory getNumberFactory()
```
    Returns the number factory.
    
    Returns:
    
    the NumberFactory used by this JEP instance.
  - getOperatorSet
```
public OperatorSet getOperatorSet()
```
    Returns the operator set.
    
    Returns:
    
    the OperatorSet used by this JEP instance.
    
    Since:
    
    2.3.0 alpha
  - getParser
```
public Parser getParser()
```
    Returns the parse object.
    
    Returns:
    
    the Parse used by this JEP.
    
    Since:
    
    2.3.0 beta 1

Class JEP

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

allowUndeclared

allowAssignment

implicitMul

symTab

funTab

errorList

parser

ev

numberFactory

opSet

Constructor Detail

JEP

JEP

JEP

Method Detail

initSymTab

initFunTab

addStandardFunctions

addStandardConstants

addComplex

addFunction

addConstant

addVariable

addVariable

addVariable

removeVariable

getVarValue

setVarValue

getVar

removeFunction

setTraverse

getTraverse

setImplicitMul

getImplicitMul

setAllowUndeclared

getAllowUndeclared

setAllowAssignment

getAllowAssignment

parseExpression

parse

evaluate

getValue

getComplexValue

getValueAsObject

hasError

getErrorInfo

getTopNode

getSymbolTable

getFunctionTable

getEvaluatorVisitor

getNumberFactory

getOperatorSet

getParser