6 ms·

Just tried this, you are correct... http://imgur.com/J9tP7lk http://imgur.com/J9tP7lk (note the incorrect bracket highlighting)

by mjmasn 11y ago

Grue3 11y ago
Jesus, how did nobody catch this before? The least a code editor should do is to match parentheses correctly.
- toomanybeersies 11y ago
  Apparently that's easier said than done.
  - zamalek 11y ago
    ... with regex.
    - mbrock 11y ago
      With anything less than a full-featured lexer and parser of the latest edition of the language in question, I'd say. Including understanding of whatever metaprogramming features or preprocessors that are in play.
      - jerf 11y ago
        It's even more than full-featured for a code editor, really, you really want a language parser that can more gracefully handle partial statements than even the core language parser itself can handle. von Neumann help you if your language was complicated to parse even before you added that requirement.
        zamalek 11y ago
        Visual Studio doesn't even do a full-blown AST - even though it has a full-blown internal parser. It frequently messes up auto-indenting when using macros involving blocks. Lexing and producing tokens with a loop is probably enough given that auto-indentation works on a subset of states of the parser, if any. As my comment alluded to, using regex is harder to both write and read than a simple loop; it's also most likely slower.
- mbrock 11y ago
  I've never used a language mode that worked properly in all cases. That's why I've stopped using them, aside from very clever and extraordinarily useful ones like paredit. It terrifies me to think about how these language modes contain regexps for matching regexp syntax. Of course those are wrong.
  - masklinn 11y ago
    > I've never used a language mode that worked properly in all cases. You need a full parser for that to happen, most mode authors don't bother[0]. JS2-mode (https://github.com/mooz/js2-mode/ https://github.com/mooz/js2-mode/) does that (or attempts to). Most syntactic colorisers are souped-up tokenisers, not actual parsers. It suffices in 99% of cases, but breaks badly elsewhere. [0] it would help if more languages made fast parsing machinery externally available as a convenient API. ALAS, that's rarely the case, even less so for fast parsing machinery which doesn't throw the information you need for syntactic coloration out the window.
    - hvis 11y ago
      I'm fairly sure that Emacs's go-mode, which doesn't use a full-blown parser, won't make the mistake of treating a paren inside a string as if it were outside either. Or if it did, that would be easy to fix. Emacs has a generic lightweight parsing facility that can tell you if you're inside a string, or a comment, or how to skip over a string, or a pair of matching parens/braces/brackets, and so on.
    - mbrock 11y ago
      The issue tracker for js2-mode illustrates that such a parsing approach is no guarantee of real-world accuracy either. https://github.com/mooz/js2-mode/issues https://github.com/mooz/js2-mode/issues The goal just shifts from having a semi-accurate regexp tokenizer, to having the language mode's complex parser match the complex parser of the language it targets—which will pretty much never happen, unless the language is exquisitely simple, like maybe restricted dialects of Scheme... or Brainfuck.
      - 11y ago

Just tried this, you are correct... http://imgur.com/J9tP7lk http://imgur.com/J9tP7lk (note the incorrect bracket highlighting)

by mjmasn 11y ago

Just tried this, you are correct... http://imgur.com/J9tP7lk http://imgur.com/J9tP7lk (note the incorrect bracket highlighting)

Grue3 11y ago

Jesus, how did nobody catch this before? The least a code editor should do is to match parentheses correctly.

toomanybeersies 11y ago
Apparently that's easier said than done.
- zamalek 11y ago
  ... with regex.
  - mbrock 11y ago
    With anything less than a full-featured lexer and parser of the latest edition of the language in question, I'd say. Including understanding of whatever metaprogramming features or preprocessors that are in play.
    - jerf 11y ago
      It's even more than full-featured for a code editor, really, you really want a language parser that can more gracefully handle partial statements than even the core language parser itself can handle. von Neumann help you if your language was complicated to parse even before you added that requirement.
      - zamalek 11y ago
        Visual Studio doesn't even do a full-blown AST - even though it has a full-blown internal parser. It frequently messes up auto-indenting when using macros involving blocks. Lexing and producing tokens with a loop is probably enough given that auto-indentation works on a subset of states of the parser, if any. As my comment alluded to, using regex is harder to both write and read than a simple loop; it's also most likely slower.
mbrock 11y ago
I've never used a language mode that worked properly in all cases. That's why I've stopped using them, aside from very clever and extraordinarily useful ones like paredit. It terrifies me to think about how these language modes contain regexps for matching regexp syntax. Of course those are wrong.
- masklinn 11y ago
  > I've never used a language mode that worked properly in all cases. You need a full parser for that to happen, most mode authors don't bother[0]. JS2-mode (https://github.com/mooz/js2-mode/ https://github.com/mooz/js2-mode/) does that (or attempts to). Most syntactic colorisers are souped-up tokenisers, not actual parsers. It suffices in 99% of cases, but breaks badly elsewhere. [0] it would help if more languages made fast parsing machinery externally available as a convenient API. ALAS, that's rarely the case, even less so for fast parsing machinery which doesn't throw the information you need for syntactic coloration out the window.
  - hvis 11y ago
    I'm fairly sure that Emacs's go-mode, which doesn't use a full-blown parser, won't make the mistake of treating a paren inside a string as if it were outside either. Or if it did, that would be easy to fix. Emacs has a generic lightweight parsing facility that can tell you if you're inside a string, or a comment, or how to skip over a string, or a pair of matching parens/braces/brackets, and so on.
  - mbrock 11y ago
    The issue tracker for js2-mode illustrates that such a parsing approach is no guarantee of real-world accuracy either. https://github.com/mooz/js2-mode/issues https://github.com/mooz/js2-mode/issues The goal just shifts from having a semi-accurate regexp tokenizer, to having the language mode's complex parser match the complex parser of the language it targets—which will pretty much never happen, unless the language is exquisitely simple, like maybe restricted dialects of Scheme... or Brainfuck.
    - 11y ago