perf(filetype): implement parent pattern pre-matching (#29660)

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Problem: calling `vim.filetype.match()` has performance bottleneck in
  that it has to match a lot of Lua patterns against several versions of
  input file name. This might be the problem if users need to call it
  synchronously a lot of times.

Solution: add "parent pattern pre-matching" which can be used to quickly
  reject several potential pattern matches at (usually rare) cost of
  adding time for one extra Lua pattern match.

  "Parent pattern" is a manually added/tracked grouping of filetype
  patterns which should have two properties:
    - Match at least the same set of strings as its filetype patterns.
      But not too much more.
    - Be fast to match.

  For them to be effective, group should consist from at least three
  filetype patterns.

  Example: for a filetpye pattern ".*/etc/a2ps/.*%.cfg", both "/etc/"
  and "%.cfg" are good parent patterns (prefer the one which can group
  more filetype patterns).

  After this commit, `vim.filetype.match()` on most inputs runs ~3.4
  times faster (while some inputs may see less impact if they match
  many parent patterns).

...

This commit is contained in:

Evgeni Chasnovski

2024-07-18 18:26:27 +03:00

committed by GitHub

parent c69ea53c9d

commit f61efe3fe7

2 changed files with 641 additions and 510 deletions

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