antlr4cs | The original , highly-optimized C # Target for ANTLR

I don't parse after every keystroke, but I do parse the entire file. This works great for intermediate-size files in the domain-specific languages I've created. Instead of trying parse only parts of the file, I use a mixed approach, parsing when the first of either of three conditions exists:

1. User types n characters
2. A timer has said that there's no change in m milliseconds.
3. For some grammars, user types line terminator/separator character;

Bottom line is, you might be surprised at how much time people spend pausing and thinking as they're typing in anything that imposes a grammar on them. These pauses can be exploited to do useful work while the user thinks, even for 400 milliseconds. I use #1 and #2 in the DSLs I've created for work due to their syntax.

The "no change" clock gets reset after every keystroke event and the n characters counter of course gets set when parsing occurs after n characters. I've found that a combination approach like this works well in an IDE type environment.

One thing to remember is, if you do this, don't mess with the text control's insertion point upon finding a syntax error, because errors are inescapable as they type. I simply show a message in a label: