Have you tried leaving actions? It sounds like that is what you want.
-Adrian
On 10-09-29 10:34 AM, Jonathan Castello wrote:
Hi Adrian,
Thanks for your help. Actually, I know how I want to buffer them; the
problem is actually extracting them when I want to. I need some way to
extract the characters only when the next character isn't plain_text
or there is no next character. I've tried adding an entry action to
cr_sequence and iac_sequence, but that doesn't work when you reach the
end of the subject data without seeing a CR or IAC. What I was hoping
to do is maintain a 'left' pointer to the first plain_text character,
and use fpc as the 'right' pointer when I reach the last contiguous
plain_text character. Then I would pass the left pointer and the
length of that contiguous stretch (fpc-left) to the user-provided
callback.
I could copy each character to a temporary buffer, but I was hoping to
avoid extra allocations. I want to just pass pointers into the
original block of text being parsed, so the calling code can do any
copying and allocating required. My entry action attempt was the
closest I could get: it would properly fire before a non plain_text
sequence, but the major issue is that it wouldn't fire at all when it
reached the end of the subject line.
Thanks again,
~Jonathan
On Wed, Sep 29, 2010 at 10:07 AM, Adrian Thurston
<[email protected]> wrote:
Hi Jonathan,
Ragel does not do any buffering of text for you. It's up to you to decide
how you want to do that, then implement it yourself. There are a couple
options. You can copy text to a buffer as you move over characters, or you
can extract them from the input buffer when you need them. The first
approach is simpler and guaranteed to work without hitches. The second
technique is faster, but you have to consider buffer block boundaries.
-Adrian
On 10-09-28 08:30 PM, Jonathan Castello wrote:
Hello,
I'm building a Telnet parser using Ragel, and I'm having an issue
making the actions do what I want. I've pasted the machine definition
to a gist: http://gist.github.com/602242
The issue is a little hard for me to describe, so I'll try to
illustrate it as best as I can. If I have a stream of input, and some
part of it is "abcdef<IAC><GA>ghi" (where<x> is a mnemonic for a
single byte), I want to emit events as such: text("abcdef"),
command("<GA>"), text("ghi"). The caller provides callbacks, and I
would pass the data to them as I interpret it.
The problem is that I can't figure out how to define actions that
would only trigger when the next character doesn't match plain_text
(or there's no more data left to parse in that particular packet), so
I can get that full stretch of characters. At the moment, I can only
get text("a"), text("b"), text("c") etc. to work, i.e. one plain_text
match at a time.
I suspect the problem is that cr_sequence and iac_sequence are
supposed to behave this way - they, too, match singular "terms" each
time before returning to the start - but here I am, wanting to give
plain_text special treatment. Am I even coming at this from the right
angle?
Thanks in advance for any advice!
~Jonathan Castello
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