Beefy Boxes and Bandwidth Generously Provided by pair Networks
No such thing as a small change
 
PerlMonks  

comment on

( [id://3333]=superdoc: print w/replies, xml ) Need Help??
Small problem: 3 + 4 6 5 7 is considered valid by your parser. You need to check to make sure all tokens were absorbed or return an EOF token and check if that's the next token. The latter method would remove the need for "no warnings 'uninitialized';".

Very good catch, thank you. I'll update the tutorial accordingly.

I think you could improve performance by generating a single regexp from @token_def (/\G(?>$ws)(?>$tok1(?{...}|$tok2(?{...}|...)/g).

Since (?{...}) is marked as experimental even in perl 5.10.0 and I (re)discovered some bugs in it, I won't use it, at least not in a tutorial at this level. Thanks for the suggestion anyway, it made me think about 5.10's named captures that could be used instead.

Also, it would be better if the lexer was an iterator instead of doing all the lexing up front. That would decrease the memory footprint.

Indeed. I decided against it because it slightly increases complexity (or at least makes it harder to understand), but I should at least mention it.

I guess I'll find some time tomorrow to incorporate your suggestions.


In reply to Re^2: Parsing with Regexes and Beyond by moritz
in thread Parsing with Regexes and Beyond by moritz

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or How to display code and escape characters are good places to start.
Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Chatterbox?
and the web crawler heard nothing...

How do I use this?Last hourOther CB clients
Other Users?
Others musing on the Monastery: (6)
As of 2024-03-28 10:38 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    No recent polls found