[bd82]

Incremental parsing is indeed amazing for IDE scenarios. But you still have to parse the entire file at least once.

For example it takes 15 seconds to parse lodash.js with Ohm (on my machine) using the sample EcmaScript grammar. But what happens if my IDE has 200 files and 400KLOC of code?

From my personal experience, if you want high performance you have to treat it as an ongoing feature, this could mean:

  * Inspect each new version for performance regressions.

  * Reinspect previous feature implementations for possible 
    performance optimizations.

  * keep track of underlying performance characteristics of your 
    runtime, for example V8 hidden class changes and other 
    de-optimization causes. These characteristics may (and do!) 
    change over time with newer releases of V8...

It would be interesting to try and optimize Ohm.js I even contributed some optimizations to Nearley.js in the past. But I'm afraid I just don't know when I will get around to trying this with too many projects and ideas competing for my time. :(