Skip to content
Cross-platform boolean expression parser and interpreter
C Ruby Java JavaScript Ragel in Ruby Host Shell C++
Latest commit 0a0d276 Jan 19, 2014 @aslakhellesoy aslakhellesoy Release 1.0.20
Failed to load latest commit information.
c Make travis pass May 14, 2013
csharp/bin Added gplex 1.2.0 and gppg 1.5.0 (Lex/Yacc clones for .NET). See #4 Feb 6, 2013
java
javascript Release 1.0.20 Jan 19, 2014
ruby Release 1.0.20 Jan 20, 2014
testdata First commit Jan 31, 2013
.gitignore Upgrade dependencies Aug 15, 2013
.travis.yml Make ruby build on different patchlevels Aug 19, 2013
CONTRIBUTING.md Update installation instructions and library versions May 2, 2013
HISTORY.md Release 1.0.20 Jan 20, 2014
LICENSE Added License and History. Feb 10, 2013
Makefile Upgrade to more recent dependencies Jan 19, 2014
README.md Explain what generators are used Aug 27, 2013
VERSION Release 1.0.20 Jan 20, 2014
bison Upgrade to more recent dependencies Jan 20, 2014
ragel

README.md

bool

Build Status

This is a cross-platform library for parsing boolean arithmetic expressions like a && b && (!c || !d) and evaluating them by assigning values to the variables.

Boolean expressions are parsed into an abstract syntax tree (AST).

This is done with a generated lexer and parser. The generators used are:

This choice of generators makes it easy to port the implementation to other languages since they are ported to most programming languages.

Evaluation of the boolean expressions is done by traversing the AST with a visitor. (This is obviously overkill for something as simple as boolean expressions, keep reading to understand why).

Supported platforms are Ruby, JRuby, Java and JavaScript. More platforms like Python, PHP and .NET may be added later.

The Ruby gem uses a C extension (for speed) and the JRuby gem uses a Java extension (also for speed). Support for e.g. Python could be added easily by using the same C code as the Ruby gem. Java programs (or any other JVM-based program such as Scala or Clojure) can also use the Java library as-is.

Why?

The purpose of this library is twofold.

First, it serves as a simple example of how to build a custom interpreted language with a fast lexer/parser that builds a visitor-traversable AST, and that runs on many different platforms. People who want to build a bigger cross-platform language could leverage the structure and build files in this project. For example, the Gherkin 3.0 project will use this project as a template.

Second, this project will be used by Cucumber to evaluate tag expressions in a more elegant way.

Building

See CONTRIBUTING.md

Something went wrong with that request. Please try again.