Mutually exclusive regular expressions

Posted by CaptnCraig on Stack Overflow See other posts from Stack Overflow or by CaptnCraig
Published on 2010-06-03T16:40:41Z Indexed on 2010/06/03 16:44 UTC
Read the original article Hit count: 186

Filed under:

regex

|

mutual-exclusion

If I have a list of regular expressions, is there an easy way to determine that no two of them will both return a match for the same string?

That is, the list is valid if and only if for all strings a maximum of one item in the list will match the entire string.

It seems like this will be very hard (maybe impossible?) to prove definitively, but I can't seem to find any work on the subject.

The reason I ask is that I am working on a tokenizer that accepts regexes, and I would like to ensure only one token at a time can match the head of the input.

© Stack Overflow or respective owner

Related posts about regex

Find multiple regex in each line and skip result if one of the regex doesn't match

as seen on Stack Overflow - Search for 'Stack Overflow'
I have a list of variables: variables = ['VariableA', 'VariableB','VariableC'] which I'm going to search for, line by line ifile = open("temp.txt",'r') d = {} match = zeros(len(variables)) for line in ifile: emptyCells=0 for i in range(len(variables)): regex = r'('+variables[i]+r')[:|=|\(](-… >>> More
OWASP Regex Repository: Is this regex correct?

as seen on Stack Overflow - Search for 'Stack Overflow'
I was looking at the regular expression for validating various data types from the (OWASP Regex Repository). One of the regular expressions in there is called safetext and looks like: ^[a-zA-Z0-9\s.\-]+$ My first question is: Is this regular expression correct? complementary question If this… >>> More
Make a Perl-style regex interpreter behave like a basic or extended regex interpreter

as seen on Stack Overflow - Search for 'Stack Overflow'
I am writing a tool to help students learn regular expressions. I will probably be writing it in Java. The idea is this: the student types in a regular expression and the tool shows which parts of a text will get matched by the regex. Simple enough. But I want to support several different regex… >>> More
JS regex isn't matching, even thought it works with a regex tester

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm writing a piece of client-side javascript code that takes a function and finds the derivative of it, however, the regex that's supposed to match with the power rule fails to work in the context of the javascript program, even though it sucessfully matches when it's used with an independent regex… >>> More
c# RegEx with "|"

as seen on Stack Overflow - Search for 'Stack Overflow'
I need to be able to check for a pattern with | in them. For example an expression like d*|*t should return true for a string like "dtest|test". I'm no regex hero so I just tried a couple of things, like: Regex Pattern = new Regex("s*\|*d"); //unable to build because of single backslash Regex Pattern… >>> More

Related posts about mutual-exclusion

PHP mutual exclusion (mutex)

as seen on Stack Overflow - Search for 'Stack Overflow'
Read some texts about locking in PHP. They all, mainly, direct to http://php.net/manual/en/function.flock.php . This page talks about opening a file on the hard-disk!! Is it really so? I mean, this makes locking really expensive - it means each time I want to lock I'll have to access the hard-disk… >>> More
Difference Between Monitor & Lock?

as seen on Stack Overflow - Search for 'Stack Overflow'
What's the difference between a monitor and a lock? If a lock is simply an implementation of mutual exclusion, then is a monitor simply a way of making use of the waiting time inbetween method executions? A good explanation would be really helpful thanks.... regards >>> More
How to prevent multiple access to a webpage?

as seen on Stack Overflow - Search for 'Stack Overflow'
Say I have a web service where I want to serve the content only once. After it is served any other access to that url should generate an error message. How would I go about doing something like this? What if 2 clients access the url in the same exact moment? >>> More
Using SQL dB column as a lock for concurrent operations in Entity Framework

as seen on Stack Overflow - Search for 'Stack Overflow'
We have a long running user operation that is handled by a pool of worker processes. Data input and output is from Azure SQL. The master Azure SQL table structure columns are approximated to [UserId, col1, col2, ... , col N, beingProcessed, lastTimeProcessed ] beingProcessed is boolean and lastTimeProcessed… >>> More
Mutually exclusive regular expressions

as seen on Stack Overflow - Search for 'Stack Overflow'
If I have a list of regular expressions, is there an easy way to determine that no two of them will both return a match for the same string? That is, the list is valid if and only if for all strings a maximum of one item in the list will match the entire string. It seems like this will be very hard… >>> More