> For roslyn, we aim for microsecond (not millisecond) parsing. Even for very large files, even if the initial parse is milliseconds, we have an incremental parser design [] that makes 99.99+% of edits happen in microseconds
I'm curious how you can make such statements involving absolute time values, without specifying what the minimum hardware requirements are.
I often write code on a 10-year-old Celeron, and I've opted for tree-sitter on the assumption that a language server would show unbearable latency, but I might have been wrong all this time. Do you claim your engine would give me sub-ms feedback on such hardware?
> I'm curious how you can make such statements involving absolute time values, without specifying what the minimum hardware requirements are.
That's a very fair point. In this case. I'm using the minimum requirements for visual studio
> Do you claim your engine would give me sub-ms feedback on such hardware?
I would expect yes, for nearly all edits. See the links I've provided in this discussion to our incremental parsing architecture.
Briefly, you can expect an edit to only cause a small handful of allocations. And the parser will be able to reuse almost the entirety of the other tree, skipping over vast swaths of it (before and after the edit) trivially.
Say you have a 100 types, each with a 100 members, each with 100 statements. An edit to a statement will trivially blow through 99 of the types, reusing them. Then in the type surrounding the edited statement, it will reuse 99 members. Then in the edited member, it will reuse 99 statements and just reparse the one affected one.
So basically it's just the computer walking 297 nodes (absolutely cheap on any machine), and reparsing a statement (also cheap).
So this should still be microseconds.
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Now. That relates to parsing. But you did say: would give me sub-ms feedback on such hardware?
So it depends on what you mean by feedback. I don't make any claims here about layers higher up and how they operate. But I can make real, measured, claims about incremental parsing performance.