4 ms·

GNU grep 2.17, 10x faster

• almosnow 13y ago
  Someone knows how was this achieved?
• reirob 13y ago
  From the NEWS section in the page: Improvements grep -i in a multibyte locale is now typically 10 times faster for patterns that do not contain \ or [. grep (without -i) in a multibyte locale is now up to 7 times faster when processing many matched lines.
• TobalJackson 13y ago
  taken from http://git.savannah.gnu.org/gitweb/?p=grep.git;a=commit;h=97318f5e59a1ef6feb8a378434a00932a3fc1e0b http://git.savannah.gnu.org/gitweb/?p=grep.git;a=commit;h=97... it seems like the speedup was achieved in the most common case of usage, which is with the -i switch (for case insensitive searching). taken from the commit log: "The trick is to realize that for some search strings, it is easy to convert to an equivalent one that is handled much more efficiently. E.G. convert this command: grep -i foobar k to this: grep '[fF][oO][oO][bB][aA][rR]' k That allows the matcher to search in buffer mode, rather than having to extract/case-convert/search each line separately. Currently, we perform this conversion only when search strings contain neither '\' nor '['."