title: How to verify and validate parsed Google Protobuf v2 file
body: <p>First, I'll just couch this in the acknowledgement, yes, I am aware of <code>protoc</code>, but I've got a specific requirement to extrapolate some specialized target language artifacts based on a <em>.proto</em> file parser outcome.</p>
  
  <p>That being established, I've already got the parser itself working. I am working on resolving imported <em>.proto</em> dependencies. Not a terribly difficult endeavor on the surface, in and of itself.</p>
  
  <p>The next steps after that, I think, are to perform a kind of "transitive linkage", as I've learned, but I am curious what I should be aware of. Prima facie, I think I should be collating a set (most likely map) of element paths to field numbers, as well as collating the reserved as well as extensions, then perhaps verifying as I traverse the <em>.proto</em> dependency tree.</p>
  
  <p>However, I'd like to get an idea of others' experience, guidance, feedback, along these lines.</p>
  
  <p>For what I'm wanting to accomplish, I do not think this verification step needs to be that elaborate, only enough to rule out invalid <em>.proto</em>, etc.</p>
  
  <p>Oh. last but not least, I need to handle this for Protobuf v2 language spec.</p>