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<regexp> that greps in the patch text) Inputs-from: Phil Hord <phil.h...@gmail.com> Signed-off-by: Ramkumar Ramachandra <artag...@gmail.com> --- Documentation/diff-options.txt | 37 ++++++++++++++++++++++++++------- Documentation/gitdiffcore.txt | 47 +++++++++++++++++++++++++----------------- 2 files changed, 57 insertions(+), 27 deletions(-) diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt index 104579d..b61a666 100644 --- a/Documentation/diff-options.txt +++ b/Documentation/diff-options.txt @@ -383,14 +383,35 @@ ifndef::git-format-patch that matches other criteria, nothing is selected. -S<string>:: - Look for differences that introduce or remove an instance of - <string>. Note that this is different than the string simply - appearing in diff output; see the 'pickaxe' entry in - linkgit:gitdiffcore for more details. + Look for commits 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 especially 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. -G<regex>:: - Look for differences whose added or removed line matches - the given <regex>. + Grep through the patch text of commits for added/removed lines + that match <regex>. `--pickaxe-regex` is implied in this + mode. ++ +To illustrate the difference between `-S<regex> --pickaxe-regex` and +`-G<regex>`, 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 didn't change). ++ +See the 'pickaxe' entry in linkgit:gitdiffcore for more +information. --pickaxe-all:: When `-S` or `-G` finds a change, show all the changes in that @@ -398,8 +419,8 @@ ifndef::git-format-patch in <string>. --pickaxe-regex:: - Make the <string> not a plain string but an extended POSIX - regex to match. + Treat the <string> not as a plain string, but an extended + POSIX regex to match. It is implied when `-G` is used. endif::git-format-patch -O<orderfile>:: diff --git a/Documentation/gitdiffcore.txt b/Documentation/gitdiffcore.txt index 568d757..d0f2b91 100644 --- a/Documentation/gitdiffcore.txt +++ b/Documentation/gitdiffcore.txt @@ -222,25 +222,34 @@ 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 -changeset easier. - +There are two kinds of pickaxe: the S kind (corresponding to 'git log +-S') and the G kind (mnemonic: grep; corresponding to 'git log -G'). + +The S kind detects filepairs whose "result" side and "origin" side +have different number of occurrences of specified string. By +definition, it will not detect in-file moves. Also, when a commit +moves a file wholesale without affecting the string being looked at, +rename detection kicks in as usual, and 'git log -S' omits the commit +(since the number of occurrences of that string didn't change in that +rename-detected filepair). The implementation essentially runs a +count, and is significantly cheaper than the G kind. + +The G kind detects filepairs whose patch text has an added or a +deleted line that matches the given regexp. This means that it can +detect in-file (or what rename-detection considers the same file) +moves. The implementation of 'git log -G' runs diff twice and greps, +and this can be quite expensive. + +When `--pickaxe-regex` is used with `-S`, treat the <string> not as a +plain string, but an extended POSIX regex to match. It is implied +when `-G` is used. + +When `--pickaxe-all` is not in effect, diffcore-pickaxe leaves only +the filepairs that touch the specified string in its output. When in +effect, diffcore-pickaxe leaves all filepairs intact if there is such +a filepair, or makes the output empty otherwise. The latter behavior +is designed to make reviewing of the changes in the context of the +whole changeset easier. diffcore-order: For Sorting the Output Based on Filenames --------------------------------------------------------- -- 220.127.116.11.432.g070c57d -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html