Tools : Jell: Parser Generator

Tools Jell: Parser Generator

3 Jell: Parser Generator

Jell is a parser generator that generates recursive descent parsers from LL(1) grammars. You can also embed extra directives to get past any of that tricky non LL(1) stuff. Now why might you want to consider a LL(1) generator over more powerful LALR recognizers?

In practice, LL(1) grammars seem to cover most portions of languages, and recursive parsers are usually easier to debug than wading through the state transitions of an LALR parser. L-attributed definitions are naturally added to the parser, and dont cause the occasional weird conflicts that an LALR parser generates when adding semantic actions. The icing on jell's particular cake is that you can define rules in a convenient extended BNF format, and you get a degree of error report and repair for free.

Other parsers which I know exist for Java -- JavaCUP, a very nice LALR parser. Also available is jb, a tcl script that postprocesses bison output and converts it to Java.

Jell is alpha code, and all I know for sure is that its parser can bootstrap itself identically. If you mail me bug reports, I'll fix them as quick as I can. Jell is freely available with source, and can be used/modified/sold/processed for llama fodder with absolutely no restrictions -- just add a note saying where you got it from.

gzip tar of source 114300 bytes
zip archive of source 155683 bytes

3.1 Sample usage
- 3.1.1 Expression grammar
- 3.1.2 Adding actions
- 3.1.3 Inheriting attributes
3.2 Using other features
- 3.2.1 Resolving ambiguous rules
- 3.2.2 Error reports
- 3.2.3 Actions and errors
- 3.2.4 Misc stuff
3.3 Reference
- 3.3.1 Options
- 3.3.2 Formal Syntax
- 3.3.3 Internals
- 3.3.4 Other java parser generators
- 3.3.5 What was stolen from whom and where

KB Sriram
Comments, bug reports: kbs@sbktech.org

Revised: Sat May 25 13:47:47 1996
URL: http://www.sbktech.org/jell.html