some shapes use unanchored patterns

[VladimirAlexiev]

(Related to #21)

Some ERA shapes use sh:pattern with an unanchored regex, eg "foo". But:

https://w3c.github.io/data-shapes/shacl/#PatternConstraintComponent refers to https://www.w3.org/TR/sparql11-query/#func-regex which refers to https://www.w3.org/TR/xpath-functions/#func-matches which says

Unless the metacharacters ^ and $ are used as anchors, the string is considered to match the pattern if any substring matches the pattern.

You can check the same at https://shacl.org/playground/

This means an unanchored pattern doesn't check the whole string. So you always want to use an anchored regex like "^foo$".

Count of such problems from search in github:

• RINF-sidings-sparql.ttl: 4 unanchored (one is commented out), 3 anchored
• RINF-contact-line-systems-sparql.ttl: 3 unanchored

I guess that public/doc/era-shapes.ttl is a concatenation of all individual shape files. Here's a grep of such problems in that file, which confirms the number 4+3:

grep -n 'sh:pattern' era-shapes.ttl |grep -Pv '"\^.*?\$"'
130:    sh:pattern "[1-9]\\d{0,5}|0" ;
146:    sh:pattern "[1-9]\\d{0,3}|0" ;
162:    sh:pattern "[1-9]\\d{0,2}|0" ; #TODO check pattern, it is defined as double
1714:   sh:pattern "([1-9]\\d{3}|[1-9]\\d{2}|[1-9]\\d{1}|[0-9])" ;
1732:   sh:pattern "([1-9]\\d{1}|[0-9])\\.[0-9]" ;
1749:   #sh:pattern "([1-9]\\d{2}|[1-9]\\d{1}|[0-9])" ;
1896:   sh:pattern "([1-9]\\d{2}|[1-9]\\d{1}|[0-9])" ;

[ednaru]

Thanks. We will add these indications to the ticket already created for issue #21