Delphi's IDE implements its code completion etc. using the real compiler parser, and has done for over a decade. The chief "tricks" are skipping method bodies other than the one the cursor is in, and otherwise having a fast parser (hand-written recursive descent / operator precedence hybrid in Delphi's case).
But completion / analysis etc. is still triggered on a pause after typing - it's not fast enough to run on every keystroke, not least because of basic reasons like having to page in referenced modules.
I agree that parsers or grammars should be reusable. I'd put parsers ahead of grammars, because frequently in practice there are some ambiguities around the edges in production grammars that are resolved using type and semantic analysis. What you want is something which can turn the text into a parse tree with the thorniest ambiguities already resolved.
Of course, doing interesting analysis with that tree is still pretty awkward if you have things like overloads in your language, to take a single example which needs pretty complete type analysis to resolve correctly in all cases.
But completion / analysis etc. is still triggered on a pause after typing - it's not fast enough to run on every keystroke, not least because of basic reasons like having to page in referenced modules.
Well, not to mention that you wouldn't want to be corrected after each keystroke anyway. "Yes, I know 'whil' is not correct, that's "why" I'm about to type an 'e'".
I actually wish there was more of a delay in Qt Creator's syntax highlighting - of course the stuff I'm working right now isn't correct yet.
But completion / analysis etc. is still triggered on a pause after typing - it's not fast enough to run on every keystroke, not least because of basic reasons like having to page in referenced modules.
I agree that parsers or grammars should be reusable. I'd put parsers ahead of grammars, because frequently in practice there are some ambiguities around the edges in production grammars that are resolved using type and semantic analysis. What you want is something which can turn the text into a parse tree with the thorniest ambiguities already resolved.
Of course, doing interesting analysis with that tree is still pretty awkward if you have things like overloads in your language, to take a single example which needs pretty complete type analysis to resolve correctly in all cases.