May 2009
Intermediate to advanced
510 pages
15h
English
Content preview from Regular Expressions Cookbook
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7.6. Validating URNs
Problem
You want to check whether a string represents a valid Uniform Resource Name (URN), as specified in RFC 2141, or find URNs in a larger body of text.
Solution
Check whether a string consists entirely of a valid URN:
\Aurn:
# Namespace Identifier
[a-z0-9][a-z0-9-]{0,31}:
# Namespace Specific String
[a-z0-9()+,\-.:=@;$_!*'%/?#]+
\Z| Regex options: Free-spacing, case insensitive |
| Regex flavors: .NET, Java, PCRE, Perl, Python, Ruby |
^urn:[a-z0-9][a-z0-9-]{0,31}:[a-z0-9()+,\-.:=@;$_!*'%/?#]+$| Regex options: Case insensitive |
| Regex flavors: .NET, Java, JavaScript, PCRE, Perl, Python |
Find a URN in a larger body of text:
\burn:
# Namespace Identifier
[a-z0-9][a-z0-9-]{0,31}:
# Namespace Specific String
[a-z0-9()+,\-.:=@;$_!*'%/?#]+| Regex options: Free-spacing, case insensitive |
| Regex flavors: .NET, Java, PCRE, Perl, Python, Ruby |
\burn:[a-z0-9][a-z0-9-]{0,31}:[a-z0-9()+,\-.:=@;$_!*'%/?#]+| Regex options: Case insensitive |
| Regex flavors: .NET, Java, JavaScript, PCRE, Perl, Python, Ruby |
Find a URN in a larger body of text, assuming that punctuation at the end of the URN is part of the (English) text in which the URN is quoted rather than part of the URN itself:
\burn:
# Namespace Identifier
[a-z0-9][a-z0-9-]{0,31}:
# Namespace Specific String
[a-z0-9()+,\-.:=@;$_!*'%/?#]*[a-z0-9+=@$/]| Regex options: Free-spacing, case insensitive |
| Regex flavors: .NET, Java, PCRE, Perl, Python, Ruby |
\burn:[a-z0-9][a-z0-9-]{0,31}:[a-z0-9()+,\-.:=@;$_!*'%/?#]*[a-z0-9+=@$/]| Regex options: Case insensitive |
| Regex flavors: ... |
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