Add lexer for ShExC

ShExC [1] is one syntax for the ShEx (shape expressions) language [2] to
describe the structure of RDF graphs (the other two syntaxes are based on
JSON-LD and RDF and don?t need special lexers). It is syntactically similar to
SPARQL, which is why a lot of the productions of ShExCLexer are copied from
SparqlLexer, but at the same time has enough differences that I feel it?s
better to simply copy the productions rather than trying to share them between
the two lexers (compare e.?g. PN_LOCAL_ESCAPE_CHARS or IRIREF).

The example file purports to be a brief schema for Pygments lexers, which I put
together from scratch to avoid licensing issues with existing example schemas;
it should not be taken too seriously.

[1]: https://shex.io/shex-semantics/#shexc
[2]: https://shexspec.github.io/primer/

1 files changed, 20 insertions, 0 deletions

diff --git a/tests/examplefiles/example.shex b/tests/examplefiles/example.shex
new file mode 100644
index 00000000..8fab2c85
--- /dev/null
+++ b/tests/examplefiles/example.shex
@@ -0,0 +1,20 @@
+PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
+PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
+PREFIX schema: <http://schema.org/>
+PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
+PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
+PREFIX ex: <http://pygments.example/#>
+
+ex:Lexer {
+  rdfs:label xsd:string;
+  skos:altLabel xsd:string*;
+  ex:filenames xsd:string+;
+  ex:mimetypes xsd:string+;
+  ex:priority xsd:decimal MinInclusive 0.0 MaxExclusive 1.0; # seems to be the de facto range of currently defined priorities
+  ex:lexes @ex:Language*;
+}
+
+ex:Language {
+  schema:description rdf:langString*;
+  schema:url IRI?;
+}