Add cached proto3 grammar loader

Introduce a `proto3_grammar` function cached with `@lang.cached_function` to parse the protobuf ABNF grammar, update the module’s `_main` to use it, and integrate this loader into the A2A spec script for parsing and validating example specs.

Author: wrmsr

omxtra/specs/proto/abnf.py

@@ -1,14 +1,26 @@
 import os.path
 
 from omlish import check
+from omlish import lang
 from omlish.text import abnf
 
 
-def _main() -> None:
+##
+
+
+@lang.cached_function(lock=True)
+def proto3_grammar() -> abnf.Grammar:
     with open(os.path.join(os.path.dirname(__file__), 'proto3.abnf')) as f:
-        gram_src = f.read()
+        src = f.read()
+
+    return abnf.parse_grammar(src, root='proto-file')
 
-    gram = abnf.parse_grammar(gram_src, root='proto-file')
+
+##
+
+
+def _main() -> None:
+    gram = proto3_grammar()
 
     with open(os.path.join(os.path.dirname(__file__), 'tests', 'examples', 'addressbook.proto')) as f:
         addressbook_src = f.read()

x/specs/a2a/spec.py

@@ -26,6 +26,15 @@ def _main() -> None:
 
     print(spec_src)
 
+    from omlish import check
+    from omlish.text import abnf
+    from omxtra.specs.proto.abnf import proto3_grammar
+
+    parsed = check.not_none(proto3_grammar().parse(spec_src))
+    parsed = abnf.only_match_rules(parsed)
+
+    print(parsed)
+
 
 if __name__ == '__main__':
     _main()