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From: | Dmitry Gutov |
Subject: | Re: master 544db1e: Faster grep pattern for identifiers |
Date: | Wed, 15 Sep 2021 19:25:25 +0300 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 |
On 15.09.2021 18:56, Eli Zaretskii wrote:
branch: master commit 544db1ee8679eec9edd5cee81a340ee1c4d70158 Author: Mattias Engdegård<mattiase@acm.org> Faster grep pattern for identifiers* lisp/cedet/semantic/symref/grep.el (semantic-symref-perform-search):Use the `-w` flag instead of wrapping the pattern in regexps that make matching much slower. This speeds up `xref-find-references` by about 3× on macOS.Doesn't this change the semantics of the "word"? The Grep notion of the word is not necessarily identical to that of Emacs, since the latter depends on the major mode. The comment in the deleted code says that much, AFAICT. Or what am I missing?
Luckily, -w actually corresponds to the regexp which the previous version of the code was using. Rather than to \<...\> which one might surmise from reading the docs for some versions of Grep (or Ripgrep).
And the comment was about \< and \>. The latest Grep manual describes it correctly: -w, --word-regexpSelect only those lines containing matches that form whole words. The test is that the matching substring must either be at the beginning of the line, or preceded by a non-word constituent character. Similarly, it must be either at the end of the line or followed by a non-word constituent character. Word-constituent characters are letters, digits, and the
underscore.
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