Revert PositionHelper refactor. Looks like it crashes on some themes.

Author: charlespwd

lib/theme_check/position_helper.rb

@@ -3,19 +3,36 @@
 
 module ThemeCheck
   module PositionHelper
+    # Apparently this old implementation is 2x slower (with benchmark/ips),
+    # so dropping with the following one... It's ugly af but
+    # this shit runs 100K+ times in one theme-check so it gotta go
+    # fast!
+    #
     def from_row_column_to_index(content, row, col)
       return 0 unless content.is_a?(String) && !content.empty?
       return 0 unless row.is_a?(Integer) && col.is_a?(Integer)
       i = 0
       safe_row = bounded(0, row, content.count("\n"))
-      charpos = -1
-      charpos = content.index("\n", charpos + 1) while i < safe_row && (i += 1) && charpos
-      result = charpos ? charpos + 1 : 0
-      next_line = content.index("\n", result)
-      upper_bound = next_line ? next_line : content.size - 1
-      bounded(result, result + col, upper_bound)
+      scanner = StringScanner.new(content)
+      scanner.scan_until(/\n/) while i < safe_row && (i += 1)
+      result = scanner.charpos || 0
+      scanner.scan_until(/\n|\z/)
+      bounded(result, result + col, scanner.pre_match.size)
     end
 
+    # def from_row_column_to_index(content, row, col)
+    #   return 0 unless content.is_a?(String) && !content.empty?
+    #   return 0 unless row.is_a?(Integer) && col.is_a?(Integer)
+    #   i = 0
+    #   safe_row = bounded(0, row, content.count("\n"))
+    #   charpos = -1
+    #   charpos = content.index("\n", charpos + 1) while i < safe_row && (i += 1) && charpos
+    #   result = charpos ? charpos + 1 : 0
+    #   next_line = content.index("\n", result)
+    #   upper_bound = next_line ? next_line : content.size - 1
+    #   bounded(result, result + col, upper_bound)
+    # end
+
     def from_index_to_row_column(content, index)
       return [0, 0] unless content.is_a?(String) && !content.empty?
       return [0, 0] unless index.is_a?(Integer)