Hi list,
I'm trying to use regular expressions to help me quickly extract the
contents of messages that my application will receive. I have worked
out most of the regex but the last section of the message has me
stumped. This is mostly because I want to pull the content out into
regex groups that I can easily access later. I have a regex to extract
the key/value pairs but it ends up with only the contents of the last
key/value pair encountered.
An example of the section of the message that is troubling me appears
like this:
{
option=value
foo=bar
another=42
option=7
}
So it's basically a bunch of lines. Every line is terminated with a
'\n' character. The number of key/value fields changes depending on
the particular message. Also notice that there are two 'option' keys.
This is allowable and I need to cater for it.
A couple of example messages are:
xpl-stat\n{\nhop=1\ nsource=vendor-device.instance \ntarget=*\n}
\nhbeat.basic\n {\ninterval=10\ n}\n
xpl-stat\n{\nhop=1\ nsource=vendor-device.instance \ntarget=vendor-
device.instance \n}\nconfig.lis t\n{\nreconf=ne wconf\noption=i nterval
\noption=group[16]\noption=filter[16]\n}\n
As all messages follow the same pattern I'm hoping to develop a
generic regex, instead of one for each message kind - because there
are many, that can pull a message from a received packet.
The regex I came up with looks like this:
# This should match any xPL message
GROUP_MESSAGE_T YPE = 'message_type'
GROUP_HOP = 'hop'
GROUP_SOURCE = 'source'
GROUP_TARGET = 'target'
GROUP_SRC_VENDO R_ID = 'source_vendor_ id'
GROUP_SRC_DEVIC E_ID = 'source_device_ id'
GROUP_SRC_INSTA NCE_ID = 'source_instanc e_id'
GROUP_TGT_VENDO R_ID = 'target_vendor_ id'
GROUP_TGT_DEVIC E_ID = 'target_device_ id'
GROUP_TGT_INSTA NCE_ID = 'target_instanc e_id'
GROUP_IDENTIFIE R_TYPE = 'identifier_typ e'
GROUP_SCHEMA = 'schema'
GROUP_SCHEMA_CL ASS = 'schema_class'
GROUP_SCHEMA_TY PE = 'schema_type'
GROUP_OPTION_KE Y = 'key'
GROUP_OPTION_VA LUE = 'value'
XplMessageGroup sRe = r'''(?P<%s>xpl-(cmnd|stat|trig ))
\n # message type
\
{\n
#
hop=(?P<%s>[1-9]{1})
\n # hop
count
source=(?P<%s>( ?P<%s>[a-z0-9]{1,8})-(?P<%s>[a-z0-9]{1,8})\.(?P<
%s>[a-z0-9]{1,16}))\n # source identifier
target=(?P<%s>( \*|(?P<%s>[a-z0-9]{1,8})-(?P<%s>[a-z0-9]{1,8})\.(?P<
%s>[a-z0-9]{1,16})))\n # target identifier
\}
\n
#
(?P<%s>(?P<%s>[a-z0-9]{1,8})\.(?P<%s>[a-z0-9]{1,8}))\n
# schema
\
{\n
#
(?:(?P<%s>[a-z0-9\-]{1,16})=(?P<%s>[\x20-\x7E]{0,128})\n){1,6 4} #
key/value pairs
\}\n''' % (GROUP_MESSAGE_ TYPE,
GROUP_HOP,
GROUP_SOURCE,
GROUP_SRC_VENDO R_ID,
GROUP_SRC_DEVIC E_ID,
GROUP_SRC_INSTA NCE_ID,
GROUP_TARGET,
GROUP_TGT_VENDO R_ID,
GROUP_TGT_DEVIC E_ID,
GROUP_TGT_INSTA NCE_ID,
GROUP_SCHEMA,
GROUP_SCHEMA_CL ASS,
GROUP_SCHEMA_TY PE,
GROUP_OPTION_KE Y,
GROUP_OPTION_VA LUE)
XplMessageGroup s = re.compile(XplM essageGroupsRe, re.VERBOSE |
re.DOTALL)
If I pass the second example message through this regex the 'key'
group ends up containing 'option' and the 'value' group ends up
containing 'filter[16]' which are the last key/value pairs in that
message.
So the problem I have lies in the key/value regex extraction section.
It handles multiple occurrences of the pattern and writes the content
into the single key/value group hence I can't extract and access all
fields.
Is there some other way to do this which allows me to store all the
key/value pairs into the regex match object for later retrieval?
Perhaps using the standard unnamed number groups?
Thanks,
Chris 2 1726
On Aug 10, 2:30*pm, clawsi...@gmail .com wrote:
I'm trying to use regular expressions to help me quickly extract the
contents of messages that my application will receive.
Don't use regexps for parsing complex data; they're limited,
completely unreadable, and hugely difficult to debug. Your code is
well written, and you've already reached the limits of the power of
regexps, and it's difficult to read.
Have a look at pyparsing for a simple solution to your problem. http://pyparsing.wikispaces.com/
--
Paul Hankin
Thanks all for your responses, especially Paul McGuire for the
excellent example usage of pyparsing.
I'm off to check out pyparsing.
Thanks,
Chris This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
by: Kenneth McDonald |
last post by:
I'm working on the 0.8 release of my 'rex' module, and would appreciate
feedback, suggestions, and criticism as I work towards finalizing the
API and feature sets. rex is a module intended to make regular expressions
easier to create and use (and in my experience as a regular expression
user, it makes them MUCH easier to create and use.)
I'm still working on formal documentation, and in any case, such
documentation isn't necessarily the...
|
by: Picho |
last post by:
Hi all,
first of all, does anyone know of a newsgroup dedicated for regular
expressions?
second - my problem:
I have a string that represents a formula of the format: "formula(...)"
the formula itself can contain other formula expressions like "Calc(...)",
"Assign(...)" etc
|
by: Laser Lu |
last post by:
Hello, everybody,
do you know how to use this Grouping Construct?
(?> )
I've found its reference on MSDN, but still can not understand it totally.
The following is its description:
Nonbacktracking subexpression (also known as a "greedy" subexpression). The
subexpression is fully matched once, and then does not participate piecemeal
|
by: Billa |
last post by:
Hi,
I am replaceing a big string using different regular expressions (see
some example at the end of the message). The problem is whenever I
apply a "replace" it makes a new copy of string and I want to avoid
that. My question here is if there is a way to pass either a memory
stream or array of "find", "replace" expressions or any other way to
avoid multiple copies of a string.
Any help will be highly appreciated
|
by: Pete Davis |
last post by:
I'm using regular expressions to extract some data and some links from some
web pages. I download the page and then I want to get a list of certain
links.
For building regular expressions, I use an app call The Regulator, which
makes it pretty easy to build and test regular expressions.
As a warning, I'm real weak with regular expressions. Let's say my regular
expression is:
| |
by: Cylix |
last post by:
I am going to write a function that the search engine done.
in search engine, we may using double quotation to specify a pharse
like "I love you",
How can I using regular expression to sperate each pharse?
test case:
"I love" all "of you"
I would like it return:
|
by: Mike |
last post by:
I have a regular expression (^(.+)(?=\s*).*\1 ) that results in
matches. I would like to get what the actual regular expression is.
In other words, when I apply ^(.+)(?=\s*).*\1 to " HEART (CONDUCTION
DEFECT) 37.33/2 HEART (CONDUCTION DEFECT) WITH
CATHETER 37.34/2 " the expression is "HEART (CONDUCTION DEFECT)". How
do I gain access to the expression (not the matches) at runtime?
Thanks,
Mike
|
by: shawnmkramer |
last post by:
Anyone every heard of the Regex.IsMatch and Regex.Match methods just
hanging and eventually getting a message "Requested Service not
found"?
I have the following pattern:
^(?<OrgCity>(+)+), City of, (?<OrgState>(()|(
+\.)))( \((?<OrgCountry>{2,})\))?$
(ignore the line wrap)
|
by: altavim |
last post by:
Usually when you make regular expression to extract text you are starting from simple expression. When you got to know target text, you are extending your expression. Subsequently very hard to ready long set of special symbols and impossible to improve such expression.
We have to create ’smart’ regular expression. Instead of write one line expression we prepare multi line text from which we shall generate our long expression. Here is a simple...
|
by: Hystou |
last post by:
Most computers default to English, but sometimes we require a different language, especially when relocating. Forgot to request a specific language before your computer shipped? No problem! You can effortlessly switch the default language on Windows 10 without reinstalling. I'll walk you through it.
First, let's disable language synchronization. With a Microsoft account, language settings sync across devices. To prevent any complications,...
|
by: Oralloy |
last post by:
Hello folks,
I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>".
The problem is that using the GNU compilers, it seems that the internal comparison operator "<=>" tries to promote arguments from unsigned to signed.
This is as boiled down as I can make it.
Here is my compilation command:
g++-12 -std=c++20 -Wnarrowing bit_field.cpp
Here is the code in...
| |
by: jinu1996 |
last post by:
In today's digital age, having a compelling online presence is paramount for businesses aiming to thrive in a competitive landscape. At the heart of this digital strategy lies an intricately woven tapestry of website design and digital marketing. It's not merely about having a website; it's about crafting an immersive digital experience that captivates audiences and drives business growth.
The Art of Business Website Design
Your website is...
|
by: Hystou |
last post by:
Overview:
Windows 11 and 10 have less user interface control over operating system update behaviour than previous versions of Windows. In Windows 11 and 10, there is no way to turn off the Windows Update option using the Control Panel or Settings app; it automatically checks for updates and installs any it finds, whether you like it or not. For most users, this new feature is actually very convenient. If you want to control the update process,...
|
by: tracyyun |
last post by:
Dear forum friends,
With the development of smart home technology, a variety of wireless communication protocols have appeared on the market, such as Zigbee, Z-Wave, Wi-Fi, Bluetooth, etc. Each protocol has its own unique characteristics and advantages, but as a user who is planning to build a smart home system, I am a bit confused by the choice of these technologies. I'm particularly interested in Zigbee because I've heard it does some...
|
by: agi2029 |
last post by:
Let's talk about the concept of autonomous AI software engineers and no-code agents. These AIs are designed to manage the entire lifecycle of a software development project—planning, coding, testing, and deployment—without human intervention. Imagine an AI that can take a project description, break it down, write the code, debug it, and then launch it, all on its own....
Now, this would greatly impact the work of software developers. The idea...
|
by: TSSRALBI |
last post by:
Hello
I'm a network technician in training and I need your help.
I am currently learning how to create and manage the different types of VPNs and I have a question about LAN-to-LAN VPNs.
The last exercise I practiced was to create a LAN-to-LAN VPN between two Pfsense firewalls, by using IPSEC protocols.
I succeeded, with both firewalls in the same network. But I'm wondering if it's possible to do the same thing, with 2 Pfsense firewalls...
|
by: 6302768590 |
last post by:
Hai team
i want code for transfer the data from one system to another through IP address by using C# our system has to for every 5mins then we have to update the data what the data is updated we have to send another system
| |
by: bsmnconsultancy |
last post by:
In today's digital era, a well-designed website is crucial for businesses looking to succeed. Whether you're a small business owner or a large corporation in Toronto, having a strong online presence can significantly impact your brand's success. BSMN Consultancy, a leader in Website Development in Toronto offers valuable insights into creating effective websites that not only look great but also perform exceptionally well. In this comprehensive...
| |