From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ramkumar Ramachandra Subject: [PATCH 2/2] diffcore-pickaxe doc: document -S and -G properly Date: Fri, 31 May 2013 17:42:15 +0530 Message-ID: <1370002335-6596-3-git-send-email-artagnon@gmail.com> References: <1370002335-6596-1-git-send-email-artagnon@gmail.com> Cc: Junio C Hamano To: Git List X-From: git-owner@vger.kernel.org Fri May 31 14:10:47 2013 Return-path: Envelope-to: gcvg-git-2@plane.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1UiOAL-0001P9-KI for gcvg-git-2@plane.gmane.org; Fri, 31 May 2013 14:10:41 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755423Ab3EaMKi (ORCPT ); Fri, 31 May 2013 08:10:38 -0400 Received: from mail-pb0-f41.google.com ([209.85.160.41]:46610 "EHLO mail-pb0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755018Ab3EaMKe (ORCPT ); Fri, 31 May 2013 08:10:34 -0400 Received: by mail-pb0-f41.google.com with SMTP id xb12so2118455pbc.14 for ; Fri, 31 May 2013 05:10:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id:x-mailer:in-reply-to:references; bh=KT7OxclGf3xLTvIzyCtZMKv4eia+rY6PBLvhbGBSyVo=; b=Oc6qtR49KzFyHcArVSJA69UzwtXbzmhhOMqTCFYSIghNNZFvacpqPgJy6YlgbDMSFI b+CmTVIYs8JVMAKi7XcFrpi5eUCxbBwUYCJEZwR7SNnj4M68ot+FrHLFO5JWS8j1uEcD D5/vXcHhsVDcdWfWYg7g8sqVRNANqc3keirKUnb/NWDqB/FxvcsCHTY++rrFoJ8nz5CJ +2LhJiMBGI3xRjQyAK63sDE+tHVdmIkeqUVCo+STV7EJxcoP3kGV7rQ56hv17ytVKq+T zWmvaha4Gn6rEt4YMhgACbVcrXKUeJkkXqbiM87B4on86hcdCwRCiZoEzn96b4IIy3En TMmw== X-Received: by 10.66.74.226 with SMTP id x2mr13121625pav.190.1370002233976; Fri, 31 May 2013 05:10:33 -0700 (PDT) Received: from luneth.maa.corp.collab.net ([182.71.239.158]) by mx.google.com with ESMTPSA id cp1sm46430663pbc.42.2013.05.31.05.10.31 for (version=TLSv1.2 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 31 May 2013 05:10:33 -0700 (PDT) X-Mailer: git-send-email 1.8.3.114.gcd03571 In-Reply-To: <1370002335-6596-1-git-send-email-artagnon@gmail.com> Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: The documentation of -S and -G is very sketchy. Completely rewrite the sections in Documentation/diff-options.txt and Documentation/gitdiffcore.txt. References: 52e9578 ([PATCH] Introducing software archaeologist's tool "pickaxe".) f506b8e (git log/diff: add -G that greps in the patch text) Inputs-from: Phil Hord Co-authored-by: Junio C Hamano Signed-off-by: Ramkumar Ramachandra --- Documentation/diff-options.txt | 38 +++++++++++++++++++++++++++-------- Documentation/gitdiffcore.txt | 45 +++++++++++++++++++++++++----------------- 2 files changed, 57 insertions(+), 26 deletions(-) diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt index b8a9b86..a85288f 100644 --- a/Documentation/diff-options.txt +++ b/Documentation/diff-options.txt @@ -383,14 +383,36 @@ ifndef::git-format-patch[] that matches other criteria, nothing is selected. -S:: - Look for differences that introduce or remove an instance of - . Note that this is different than the string simply - appearing in diff output; see the 'pickaxe' entry in - linkgit:gitdiffcore[7] for more details. + Look for differences that change the number of occurrences of + the specified string (i.e. addition/deletion) in a file. + Intended for the scripter's use. ++ +It is useful when you're looking for an exact block of code (like a +struct), and want to know the history of that block since it first +came into being: use the feature iteratively to feed the interesting +block in the preimage back into `-S`, and keep going until you get the +very first version of the block. -G:: - Look for differences whose added or removed line matches - the given . + Look for differences whose patch text contains added/removed + lines that match . ++ +To illustrate the difference between `-S --pickaxe-regex` and +`-G`, consider a commit with the following diff in the same +file: ++ +---- ++ return !regexec(regexp, two->ptr, 1, ®match, 0); +... +- hit = !regexec(regexp, mf2.ptr, 1, ®match, 0); +---- ++ +While `git log -G"regexec\(regexp"` will show this commit, `git log +-S"regexec\(regexp" --pickaxe-regex` will not (because the number of +occurrences of that string did not change). ++ +See the 'pickaxe' entry in linkgit:gitdiffcore[7] for more +information. --pickaxe-all:: When `-S` or `-G` finds a change, show all the changes in that @@ -398,8 +420,8 @@ ifndef::git-format-patch[] in . --pickaxe-regex:: - Make the not a plain string but an extended POSIX - regex to match. + Treat the given to `-S` as an extended POSIX regular + expression to match. endif::git-format-patch[] -O:: diff --git a/Documentation/gitdiffcore.txt b/Documentation/gitdiffcore.txt index 568d757..c8b3e51 100644 --- a/Documentation/gitdiffcore.txt +++ b/Documentation/gitdiffcore.txt @@ -222,26 +222,35 @@ version prefixed with '+'. diffcore-pickaxe: For Detecting Addition/Deletion of Specified String --------------------------------------------------------------------- -This transformation is used to find filepairs that represent -changes that touch a specified string, and is controlled by the --S option and the `--pickaxe-all` option to the 'git diff-*' -commands. - -When diffcore-pickaxe is in use, it checks if there are -filepairs whose "result" side and whose "origin" side have -different number of specified string. Such a filepair represents -"the string appeared in this changeset". It also checks for the -opposite case that loses the specified string. - -When `--pickaxe-all` is not in effect, diffcore-pickaxe leaves -only such filepairs that touch the specified string in its -output. When `--pickaxe-all` is used, diffcore-pickaxe leaves all -filepairs intact if there is such a filepair, or makes the -output empty otherwise. The latter behaviour is designed to -make reviewing of the changes in the context of the whole +This transformation limits the set of filepairs to those that change +specified strings between the preimage and the postimage in a certain +way. -S and -G options are used to +specify different ways these strings are sought. + +"-S" detects filepairs whose preimage and postimage +have different number of occurrences of the specified block of text. +By definition, it will not detect in-file moves. Also, when a +changeset moves a file wholesale without affecting the interesting +string, diffcore-rename kicks in as usual, and `-S` omits the filepair +(since the number of occurrences of that string didn't change in that +rename-detected filepair). When used with `--pickaxe-regex`, treat +the as an extended POSIX regular expression to match, +instead of a literal string. + +"-G" (mnemonic: grep) detects filepairs whose +textual diff has an added or a deleted line that matches the given +regular expression. This means that it will detect in-file (or what +rename-detection considers the same file) moves, which is noise. The +implementation runs diff twice and greps, and this can be quite +expensive. + +When `-S` or `-G` are used without `--pickaxe-all`, only filepairs +that match their respective criterion are kept in the output. When +`--pickaxe-all` is used, if even one filepair matches their respective +criterion in a changeset, the entire changeset is kept. This behavior +is designed to make reviewing changes in the context of the whole changeset easier. - diffcore-order: For Sorting the Output Based on Filenames --------------------------------------------------------- -- 1.8.3.114.gcd03571