- About Scala
- Documentation
- Code Examples
- Software
- Scala Developers
Mirror Parser
Thu, 2009-02-05, 15:48
Using the parser combinator library, I'd like to have a parser that recognizes these constructs:
[ ]
[. .]
[| |]
[> <]
[+> <+]
Note a few things:
1) The series of opening symbols after the [ is an arbitrary sequence of a certain set of characters.
2) The closing symbols are defined by the opening symbols.
3) The closing symbols aren't simply the opening symbols in reverse order, but are a specific
"mirror" token ('[' mirrored by ']', '<' mirrored by '<', etc.)
4) Another parser will execute between open and close. But that's not a big deal.
Any tips on how to code up such a requirement? I'm a bit stumped on how to express that.
~~ Robert Fischer.
Grails Trainining http://GroovyMag.com/training
Smokejumper Consulting http://SmokejumperIT.com
Enfranchised Mind Blog http://EnfranchisedMind.com/blog
Check out my book, "Grails Persistence with GORM and GSQL"!
http://www.smokejumperit.com/redirect.html
Thu, 2009-02-05, 17:57
#2
Re: Mirror Parser
The #scala channel on IRC came through with a to use "into", which looks like it does what I want.
Here's an example of its usage:
http://paste.pocoo.org/show/102878/
~~ Robert Fischer.
Grails Trainining http://GroovyMag.com/training
Smokejumper Consulting http://SmokejumperIT.com
Enfranchised Mind Blog http://EnfranchisedMind.com/blog
Check out my book, "Grails Persistence with GORM and GSQL"!
http://www.smokejumperit.com/redirect.html
Jens Alfke wrote:
>
> On Feb 5, 2009, at 6:47 AM, Robert Fischer wrote:
>
>> Any tips on how to code up such a requirement? I'm a bit stumped on
>> how to express that.
>
> You may need to write a custom lexer for that. That's a type of
> tokenization that can't really be handled by a standard lexer. The
> chapter on parsing in the Artima book has a section that describes how
> to separate the lexing and parsing.
>
> (Disclaimer: I've never used the Scala parser classes, though I've
> written my own parsers in the dim past.)
>
> —Jens
On Feb 5, 2009, at 6:47 AM, Robert Fischer wrote:
> Any tips on how to code up such a requirement? I'm a bit stumped on
> how to express that.
You may need to write a custom lexer for that. That's a type of
tokenization that can't really be handled by a standard lexer. The
chapter on parsing in the Artima book has a section that describes how
to separate the lexing and parsing.
(Disclaimer: I've never used the Scala parser classes, though I've
written my own parsers in the dim past.)
—Jens