Wyjec - general-purpose expression language

The Wyjec is a general-purpose expression language with simple prefix notation. It's also a name of pure-Java implementation of the language, that can be embedded in various Java applications and customised for their specific needs. Wyjec is Free Software so you can read, modify and redistribute its source code, as long as you conform to its license requirements.

Latest release

2005-12-05: Wyjec 1.0

Features:

Generic engine for processing arbitrarily complex expressions written using prefix notation.
Supported data types: boolean, integer, string, float, date.
Support for overloaded function names.
Lazy evaluation of parameters for selected functions.
Separation of parsing and evaluating phases allows caching parsed forms of expressions.
Implementations of functions are simple Java classes.
Over 100 standard functions available in the library.
Full documentation for the library API and for standard functions.
Real-time applications friendly. Up to predefined level of expression complexity no objects are created during expression processing (covers both parsing and evaluating engine and all standard functions).
Pure Java implementation.
Designed for Java 1.4. Slightly modified Java 1.2 version of the library is also available.
Works with gcj and classpath.

See release history for information about previous releases.

Documentation

As a first step, you should read Wyjec language tutorial, which describes the most important concepts of the language without touching any implementation aspects.

After reading the language tutorial, look over Wyjec standard functions documentation so that you know what kinds of functions are available with Wyjec implementation by default. Also keep this document at hand when using Wyjec language with any Wyjec-based application.

For a short introduction to using Wyjec in your application read Wyjec applications developers tutorial.

After gaining some experience with Wyjec you may want to implement your own Functions. Start with reading Wyjec functions developers tutorial.

When integrating Wyjec with your application or implementing your own functions, please refer to Wyjec API documentation.

No matter what's your area of interest in Wyjec, you should take a look at Wyjec Tools.

You can see the simplicity of the expression language by looking at its grammar.

Testing

A set of JUnit tests for wyjec library is available as "wyjec-tests" package (available in download section). According to EMMA reports these tests cover over 99% of code blocks and lines of code of the library. 100% of the tests pass successfully.

Coding style

I use Checkstyle to assure uniform coding style across the project and to check many other aspects of the source code. Checkstyle configuration file used for Wyjec is available here.

Download

Package: wyjec
Version: 1.0
Description: core part of the Wyjec implementation, for use in Java applications as a library; it doesn't contain any directly executable parts.
License: GNU Lesser General Public License (GNU LGPL)
Source: wyjec-1.0.tar.bz2, wyjec-1.0.zip
Java byte-code binary: wyjec-1.0.jar
Source for Java 1.2: wyjec-1.0-java1.2.tar.bz2, wyjec-1.0-java1.2.zip
Java byte-code binary for Java 1.2: wyjec-1.0-java1.2.jar

Package: wyjec-tests
Version: 1.0
Description: JUnit tests for core part of the Wyjec implementation ("wyjec" package).
License: GNU General Public License (GNU GPL)
Source: wyjec-tests-1.0.tar.bz2, wyjec-tests-1.0.zip
Java byte-code binary: wyjec-tests-1.0.jar

Package: wyjec-tools
Version: 1.0
Description: a set of tools for developers of Wyjec functions and (in the limited scope) for end-users writing Wyjec expressions.
License: GNU General Public License (GNU GPL)
Source: wyjec-tools-1.0.tar.bz2, wyjec-tools-1.0.zip
Java byte-code binary: wyjec-tools-1.0.jar