JEvaluator

© 2006,2007 Fabrizio Fiorucci

Welcome to the homepage of this project!

In case of requests, bugs, issues, questions and further developments you can reach me at:

e-mail: fiorucci@oasi.asti.it
ICQ: 6578881
MSN: fiorucci@oasi.asti.it
Skype: fabriziofiorucci

Commercial support

An agreement has been worked on with AT Technologies for all kinds of commercial support for this project.
Commercial enquiries should be addressed to jevaluator@at-technologies.it

Overview

JEvaluator is a Java class that implements a fast and flexible mathematical expressions parser and evaluator.
It's fully compatible with Java 1.4 and greater.
Complex mathematical expressions can be handled and combined together with virtually no limitations on length and number of used variables.

JEvaluator main features include:

No restrictions on the number and length of expressions
No restrictions on the number of variables that can be used
Dynamic and automatic creation of variables
No restrictions on variables names, they can be any alphanumeric string starting with a literal
Support for single-parameter and multi-parameter functions ( ie. abs(p), avg(p1,p2,...pn) ).
Functions parameters can be either values or expressions.

Functions that are currently provided with JEvaluator are:

Function	Description
Abs(p)	Absolute value of p
And(p1, p2)	Boolean AND (p1 && p2)
Avg(p1, p2, ..., pn)	Average value among p1, p2, ..., pn
Case(cond1,result1,cond2,result2,...)	Matches multiple conditions to multiple expressions. If cond1 is true, the result is result1, else if cond2 is true, the result is result2, ... In case no condition is matched, the result is NaN
If(cond,ifTrue,ifFalse)	if cond is true, result is the expression "ifTrue", "ifFalse" otherwise
Log(p)	Natural logarithm (base e) of p
Min(p1, p2, ..., pn)	Minimum value among p1, p2, ..., pn
Max(p1, p2, ..., pn)	Maximum value among p1, p2, ..., pn
Or(p1, p2)	Boolean OR (p1 \|\| p2)
Random(p)	Random value amon 0 and p
Rounddown(p)	p rounded down to the closest integer
Roundup(p)	p rounded up to the closest integer
Sqrt(p)	The square root for p
Strlen(s)	The length in characters of the string variable
Sum(p1, p2, ..., pn)	The sum of all parameters
Val(p)	The value of p

Support for arithmetical operators:

Operator

Description

+

Sum

-

Subtraction

*

Multiplication

/

Division

^

Power

Support for logical operators: logical operators return a boolean value, either 0 or 1

Operator	Description	Example
<	Lesser than	2<(a*(4-c)) sqrt(a^2)<7-log(22)
>	Greater than	avg(4-c,72,sum(1,2,3))>0
?	Equals to	2?0 (a+b)*(c-2/e)?avg(log(c-4),3)

Support for boolean operators: operands are implicitly converted into integer before performing the boolean operations

Operator	Description	Example
&	Bitwise AND	2&(a*(4-c)) sqrt(a^2)&7-log(22)
\|	Bitwise inclusive OR	avg(4-c,72,sum(1,2,3))\|32
!	Bitwise exclusive OR	3!35 (a+b)*(c-2/e)!avg(log(c-4),3)

Support for user-defined functions
LGPL-licensed ;-)

Quickstart

For a quickstart download the tarball and have a look at JEvaluatorTest.java and JEvaluator.conf.
User-defined functions are supported and can be easily implemented by implementing the BaseFunctionInterface interface. For some quick hint have a look at Sum.java.

Basic steps to start using JEvaluator are:

Initialization

Instantiate JEvaluator

JEvaluator expr = new JEvaluator();

Initialize instance against log4j configuration file

if ( expr.init ( "etc/JEvaluator.conf" ) ==false )
{
// LOG4J INIT ERROR, ABORTING
}

Variables definition

Using name and value

expr.setVar ( "base","120" );
expr.setVar ( "doubleBase","base*2" );

Using name and value as an expression

expr.setExpr ( "height=45" );
expr.setExpr ( "area=base*height/2" );

Variables retrieval

Using name

Double base = expr.getVar ( "base" );

Text parsing and expansion

expr.evaluateText ( "this is the average: ${output=average} and this is our final sum ${output=finalSum}", "output" );

Checking whether a variable is being used

if ( expr.isVarDefined ( "base" ) == true )
{
// VARIABLE "base" EXISTS
}

User-defined functions handling

Registration

expr.registerFunction ( new Avg() );

Unregistration by function object
Unregistration by function name

expr.unregisterFunction ( new Avg() );
expr.unregisterFunction ( "avg" );

Registration check by function object
Registration check by function name

expr.isFunctionRegistered ( new Avg() );
expr.isFunctionRegistered ( "avg" );

Download & documentation

JEvaluator can be downloaded here:

Filename	MD5 checksum	Documentation	Release date	Java compatibility
JEvaluator 0.9.J4	b5fb5e523eb73a8e5df179c7006df9bb	Javadoc	October 6th, 2007	1.4
JEvaluator 0.9.J5	d36fa4e987e14b7dfc075bab4159c784	Javadoc	October 6th, 2007	1.5
JEvaluator 0.9.J6	0e0ef45078d4b8be215d061ef509ee6d	Javadoc	October 6th, 2007	1.6
JEvaluator 0.8.J4	420776f9cc63afbfb7057c735820ee1e	Javadoc	August 29th, 2007	1.4
JEvaluator 0.8.J5	44949138c9f9c3c1dbfa86922a6c6f6d	Javadoc	August 29th, 2007	1.5
JEvaluator 0.8.J6	1dd05d83e7515e39e4aebc023ae64e25	Javadoc	August 29th, 2007	1.6
JEvaluator 0.7.1	28d8d59b88768d35fbd4587f943f6f57	Javadoc	August 6th, 2007	1.4
JEvaluator 0.7	254e7f1130f95e72717d90b132a2778c	Javadoc	July 30th, 2007	1.5
JEvaluator 0.6	1482b642518bd2b155a65b07017b25e0	Javadoc	November 8th, 2006	1.5
JEvaluator 0.5	d34d290be29d1eb506218820074dbc70	Javadoc	October 9th, 2006	1.5
JEvaluator 0.4	f785db936951b9a3fa8315ae1c79fad3	Javadoc	September 7th, 2006	1.5
JEvaluator 0.3	b4efa40a4627f2beb38b25e43059865b	Javadoc	July 27th, 2006	1.4 & 1.5
JEvaluator 0.2	9dadbceb09a9f19537471085ffeff7ed	Javadoc	July 27th, 2006	1.4 & 1.5
JEvaluator 0.1b	deae23dfb03f54b570f65fb5668b9890	Javadoc	July 9th, 2006	1.4 & 1.5

JEvaluator distribution files can be imported directly as an Eclipse project

License

JEvaluator - A Java parsing and evaluation class
Copyright (C) 2006, 2007  Fabrizio Fiorucci

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

http://www.gnu.org/licenses/lgpl.html

Credits

JEvaluator uses log4j by the Apache Software Foundation.

To do

Support for more logical operators
Improved support for conditional branching and loops
Code cleanup
...

In case of feature requests please drop me an e-mail

ChangeLog

0.9 - Major enhancements: support for boolean operators and boolean bitwise operators (three subreleases for Java 1.4, 1.5 and 1.6) - October 6th, 2007
0.8 - Major enhancements: support for text with inline expressions expansion (three subreleases for Java 1.4, 1.5 and 1.6) - August 28th, 2007
0.7.1 - Minor enhancements: 0.7 release backported to be compatible with Java 1.4 - August 6th, 2007
0.7 - Minor enhancements: small bugfixes - July 30th, 2007
0.6 - Major enhancements: support for literal and string variables - November 8th, 2006
0.5 - Major enhancements: support for conditional and branch-case expressions - October 9th, 2006
0.4 - Minor enhancements: strict declarations according to Java 5 specifications added. Script to run the example code fixed - September 7th, 2006
0.3 - License changed from GPL to LGPL - July 27th, 2006
0.2 - Added support for dynamic registration/unregistration of user-defined functions - July 27th, 2006
0.1b - First public release - July 9th, 2006

Listed on:

Related projects:

STX Expression Parser C++ Framework by Timo Bingmann

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Operator	Description
+	Sum
-	Subtraction
*	Multiplication
/	Division
^	Power

Initialization
Instantiate JEvaluator	JEvaluator expr = new JEvaluator();
Initialize instance against log4j configuration file	if ( expr.init ( "etc/JEvaluator.conf" ) ==false ) { // LOG4J INIT ERROR, ABORTING }
Variables definition
Using name and value	expr.setVar ( "base","120" ); expr.setVar ( "doubleBase","base*2" );
Using name and value as an expression	expr.setExpr ( "height=45" ); expr.setExpr ( "area=base*height/2" );
Variables retrieval
Using name	Double base = expr.getVar ( "base" );
Text parsing and expansion
expr.evaluateText ( "this is the average: ${output=average} and this is our final sum ${output=finalSum}", "output" );
Checking whether a variable is being used	if ( expr.isVarDefined ( "base" ) == true ) { // VARIABLE "base" EXISTS }
User-defined functions handling
Registration	expr.registerFunction ( new Avg() );
Unregistration by function object Unregistration by function name	expr.unregisterFunction ( new Avg() ); expr.unregisterFunction ( "avg" );
Registration check by function object Registration check by function name	expr.isFunctionRegistered ( new Avg() ); expr.isFunctionRegistered ( "avg" );