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Regular Expressions Cookbook
book

Regular Expressions Cookbook

by Jan Goyvaerts, Steven Levithan
May 2009
Intermediate to advanced
510 pages
15h
English
O'Reilly Media, Inc.
Content preview from Regular Expressions Cookbook

7.12. Extracting the Path from a URL

Problem

You want to extract the path from a string that holds a URL. For example, you want to extract /index.html from http://www.regexcookbook.com/index.html or from /index.html#fragment.

Solution

Extract the path from a string known to hold a valid URL. The following finds a match for all URLs, even for URLs that have no path:

\A
# Skip over scheme and authority, if any
([a-z][a-z0-9+\-.]*:(//[^/?#]+)?)?
# Path
([a-z0-9\-._~%!$&'()*+,;=:@/]*)
Regex options: Free-spacing, case insensitive
Regex flavors: .NET, Java, PCRE, Perl, Python, Ruby
^([a-z][a-z0-9+\-.]*:(//[^/?#]+)?)?([a-z0-9\-._~%!$&'()*+,;=:@/]*)
Regex options: Case insensitive
Regex flavors: .NET, Java, JavaScript, PCRE, Perl, Python, Ruby

Extract the path from a string known to hold a valid URL. Only match URLs that actually have a path:

\A
# Skip over scheme and authority, if any
([a-z][a-z0-9+\-.]*:(//[^/?#]+)?)?
# Path
(/?[a-z0-9\-._~%!$&'()*+,;=@]+(/[a-z0-9\-._~%!$&'()*+,;=:@]+)*/?|/)
# Query, fragment, or end of URL
([#?]|\Z)
Regex options: Free-spacing, case insensitive
Regex flavors: .NET, Java, PCRE, Perl, Python, Ruby
^([a-z][a-z0-9+\-.]*:(//[^/?#]+)?)?(/?[a-z0-9\-._~%!$&'()*+,;=@]+↵
(/[a-z0-9\-._~%!$&'()*+,;=:@]+)*/?|/)([#?]|$)
Regex options: Case insensitive
Regex flavors: .NET, Java, JavaScript, PCRE, Perl, Python, Ruby

Extract the path from a string known to hold a valid URL. Use atomic grouping to match only those URLs that actually have a path:

\A # Skip over scheme and authority, if ...
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Publisher Resources

ISBN: 9780596802837Catalog PageErrata