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authorLibravatar Junio C Hamano <gitster@pobox.com>2013-07-03 15:41:17 -0700
committerLibravatar Junio C Hamano <gitster@pobox.com>2013-07-03 15:41:17 -0700
commit4efd16543fe1c0871742dbd33d6adc2acfd11c3c (patch)
tree322061af94a0b48657d617e47c3b2705381dac31 /Documentation
parentMerge branch 'cr/git-work-tree-sans-git-dir' into maint (diff)
parentdiffcore-pickaxe doc: document -S and -G properly (diff)
downloadtgif-4efd16543fe1c0871742dbd33d6adc2acfd11c3c.tar.xz
Merge branch 'rr/diffcore-pickaxe-doc' into maint
* rr/diffcore-pickaxe-doc: diffcore-pickaxe doc: document -S and -G properly diffcore-pickaxe: make error messages more consistent
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/diff-options.txt38
-rw-r--r--Documentation/gitdiffcore.txt45
2 files changed, 57 insertions, 26 deletions
diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt
index b8a9b86375..a85288f23e 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<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[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<regex>::
- Look for differences whose added or removed line matches
- the given <regex>.
+ Look for differences whose patch text contains added/removed
+ lines that match <regex>.
++
+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, &regmatch, 0);
+...
+- hit = !regexec(regexp, mf2.ptr, 1, &regmatch, 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 <string>.
--pickaxe-regex::
- Make the <string> not a plain string but an extended POSIX
- regex to match.
+ Treat the <string> given to `-S` as an extended POSIX regular
+ expression to match.
endif::git-format-patch[]
-O<orderfile>::
diff --git a/Documentation/gitdiffcore.txt b/Documentation/gitdiffcore.txt
index 568d75783a..c8b3e51c84 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<block of text> and -G<regular expression> options are used to
+specify different ways these strings are sought.
+
+"-S<block of text>" 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 <block of text> as an extended POSIX regular expression to match,
+instead of a literal string.
+
+"-G<regular expression>" (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
---------------------------------------------------------