From f448e2b9951e1893df9741e21dd9a786d2ca020c Mon Sep 17 00:00:00 2001
From: Earlopain <14981592+Earlopain@users.noreply.github.com>
Date: Wed, 26 Nov 2025 16:13:04 +0100
Subject: [PATCH] Optimize `Prism::Source#find_line`

This is more concise and ruby does a better job performance-wise.

This used to be `bsearch_index` already but https://github.com/ruby/prism/commit/6d8358c08395438d5924777c1fc3001a5ebf0aa3 changed it.
https://github.com/ruby/prism/pull/1733#discussion_r1373702087 said:
> Yeah the edge case was that the value matched an element exactly

But surely there would be a test to show this behaviour?

Gets called as part of pretty-printing nodes.
Further reduces the time for `SnapshotsTest` by ~16% for me.
---
 lib/prism/parse_result.rb | 17 ++---------------
 1 file changed, 2 insertions(+), 15 deletions(-)

diff --git a/lib/prism/parse_result.rb b/lib/prism/parse_result.rb
index 05c14e33f5..3570af136a 100644
--- a/lib/prism/parse_result.rb
+++ b/lib/prism/parse_result.rb
@@ -155,21 +155,8 @@ def deep_freeze
     # Binary search through the offsets to find the line number for the given
     # byte offset.
     def find_line(byte_offset)
-      left = 0
-      right = offsets.length - 1
-
-      while left <= right
-        mid = left + (right - left) / 2
-        return mid if (offset = offsets[mid]) == byte_offset
-
-        if offset < byte_offset
-          left = mid + 1
-        else
-          right = mid - 1
-        end
-      end
-
-      left - 1
+      index = offsets.bsearch_index { |offset| offset > byte_offset } || offsets.length
+      index - 1
     end
   end