chemaxon.jep
Class ChemJEP

java.lang.Object
  chemaxon.nfunk.jep.JEP
      chemaxon.jep.ChemJEP

All Implemented Interfaces:

chemaxon.marvin.util.CallbackIface, java.io.Serializable

public class ChemJEP
extends chemaxon.nfunk.jep.JEP
implements chemaxon.marvin.util.CallbackIface

Expression parser and evaluator for chemical expressions.

Since:

JChem 2.2, Marvin 5.1

Author:

Nora Mate

See Also:

Serialized Form

Field Summary

static int	FALSE Logical result value: FALSE.
static int	TRUE Logical result value: TRUE.
static int	UNDECIDED Logical result value: UNDECIDED.

Fields inherited from class chemaxon.nfunk.jep.JEP

allowUndeclared, COMPILE_ERROR, errorList, EVALUATION_ERROR, funTab, implicitMul, symTab

Constructor Summary

ChemJEP()
Constructor.

ChemJEP(java.lang.Class contextClass)
Constructor.

Method Summary

void	addFunction(java.lang.String name, chemaxon.nfunk.jep.function.PostfixMathCommandI function) Adds a new function to the parser.
java.lang.Object	callback(java.lang.String method, java.lang.Object arg) Delegates CallbackIface.callback(String, Object) to the context.
void	compile(java.lang.String expression) Compiles the expression string to an inner structure.
boolean	evaluate_boolean(ChemContext context) Evaluates the expression and converts the result boolean.
boolean[]	evaluate_booleans(ChemContext context) Evaluates the expression and converts the result to boolean[].
double	evaluate_double(ChemContext context) Evaluates the expression and converts the result to double.
double[]	evaluate_doubles(ChemContext context) Evaluates the expression and converts the result to double[].
java.lang.Object	evaluate(ChemContext context) Evaluates the expression.
static int	getLogicalValue(java.lang.Object result) Returns the logical correspondent of the specified result object: TRUE, FALSE or UNDECIDED.
static boolean	isUndecided(java.lang.Object result) Returns whether the result object is undecided.
protected void	setSymbolTable(chemaxon.nfunk.jep.SymbolTable symTab) Sets the SymbolTable object.

Methods inherited from class chemaxon.nfunk.jep.JEP

addComplex, addComplexVariable, addError, addStandardConstants, addStandardFunctions, addVariable, addVariableAsObject, getComplexValue, getError, getErrorCount, getErrorInfo, getErrors, getFunction, getNumberFactory, getSymbolTable, getTopNode, getValue, getValueAsObject, hasError, initFunTab, initSymTab, parseExpression, removeFunction, removeVariable, setAllowUndeclared, setImplicitMul, setTraverse

Methods inherited from class java.lang.Object

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

Field Detail

FALSE

public static final int FALSE

Logical result value: FALSE.

See Also:

Constant Field Values

TRUE

public static final int TRUE

Logical result value: TRUE.

See Also:

Constant Field Values

UNDECIDED

public static final int UNDECIDED

Logical result value: UNDECIDED.

See Also:

Constant Field Values

Constructor Detail

ChemJEP

public ChemJEP()
        throws chemaxon.nfunk.jep.ParseException

Constructor. Initiates the this JEP with no context.

Throws:

chemaxon.nfunk.jep.ParseException - on error

ChemJEP

public ChemJEP(java.lang.Class contextClass)
        throws chemaxon.nfunk.jep.ParseException

Constructor. Sets the context class, adds context functions.

Parameters:

contextClass - is the context class

Throws:

chemaxon.nfunk.jep.ParseException - on error

Method Detail

addFunction

public void addFunction(java.lang.String name,
                        chemaxon.nfunk.jep.function.PostfixMathCommandI function)
                 throws chemaxon.nfunk.jep.ParseException

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.

Overrides:

addFunction in class chemaxon.nfunk.jep.JEP

Parameters:

name - is the name of the function

function - is the function object that is used for evaluating the function

Throws:

chemaxon.nfunk.jep.ParseException - if there exists a function with the same name

setSymbolTable

protected void setSymbolTable(chemaxon.nfunk.jep.SymbolTable symTab)

Sets the SymbolTable object.

Parameters:

symTab - is the SymbolTable object

compile

public void compile(java.lang.String expression)
             throws chemaxon.nfunk.jep.ParseException

Compiles the expression string to an inner structure. This speeds-up evaluation.

Parameters:

expression - is the expression string

Throws:

chemaxon.nfunk.jep.ParseException - on compile error

callback

public java.lang.Object callback(java.lang.String method,
                                 java.lang.Object arg)

Delegates CallbackIface.callback(String, Object) to the context.

Specified by:

callback in interface chemaxon.marvin.util.CallbackIface

Parameters:

method - is the method name

arg - is the method argument

evaluate

public java.lang.Object evaluate(ChemContext context)
                          throws chemaxon.nfunk.jep.ParseException

Evaluates the expression. The expression string must have been given and compiled beforehand by compile(String expression).

Parameters:

context - is the evaluation context

Returns:

the evaluation result

Throws:

chemaxon.nfunk.jep.ParseException - on evaluation error

evaluate_double

public double evaluate_double(ChemContext context)
                       throws chemaxon.nfunk.jep.ParseException

Evaluates the expression and converts the result to double. The expression string must have been given and compiled beforehand by compile(String expression).

Parameters:

context - is the evaluation context

Returns:

the evaluation result

Throws:

EvaluationException - on evaluation error

chemaxon.nfunk.jep.ParseException

evaluate_doubles

public double[] evaluate_doubles(ChemContext context)
                          throws chemaxon.nfunk.jep.ParseException

Evaluates the expression and converts the result to double[]. This is useful if the result is an object array in which case each element is converted to double. The expression string must have been given and compiled beforehand by compile(String expression).

Parameters:

context - is the evaluation context

Returns:

the evaluation result

Throws:

EvaluationException - on evaluation error

chemaxon.nfunk.jep.ParseException

evaluate_boolean

public boolean evaluate_boolean(ChemContext context)
                         throws chemaxon.nfunk.jep.ParseException

Evaluates the expression and converts the result boolean. Boolean return values are returned as double: 1.0 for true and 0.0 for false. This function returns true for a value greater than 0.5, false otherwise. This means that for boolean expressions the return value will be OK (and we also eliminated floating-point comparison inaccuracy :-). The expression string must have been given and compiled beforehand by compile(String expression).

Parameters:

context - is the evaluation context

Returns:

the evaluation result

Throws:

EvaluationException - on evaluation error

chemaxon.nfunk.jep.ParseException

evaluate_booleans

public boolean[] evaluate_booleans(ChemContext context)
                            throws chemaxon.nfunk.jep.ParseException

Evaluates the expression and converts the result to boolean[]. This is useful if the result is an object array in which case each element is converted to boolean. The expression string must have been given and compiled beforehand by compile(String expression).

Parameters:

context - is the evaluation context

Returns:

the evaluation result

Throws:

EvaluationException - on evaluation error

chemaxon.nfunk.jep.ParseException

getLogicalValue

public static int getLogicalValue(java.lang.Object result)

Returns the logical correspondent of the specified result object: TRUE, FALSE or UNDECIDED.

Parameters:

result - is the result object

Returns:

the corresponding logical value

Since:

JChem 3.2

isUndecided

public static boolean isUndecided(java.lang.Object result)

Returns whether the result object is undecided.

Returns:

true if the result is undecided