X-Git-Url: https://git.verplant.org/?a=blobdiff_plain;f=Documentation%2Fdiffcore.txt;h=a0ffe85a25365974c2d3c17ec2cafe26d94602cf;hb=bc6146d2abcf3800eb3683cfe972cabd38ff4796;hp=45620f8fb05ccfa9ee36f1a44b0f449e3c43e259;hpb=28f8fafff8511d4f03f956819f7819b481d7fd50;p=git.git diff --git a/Documentation/diffcore.txt b/Documentation/diffcore.txt index 45620f8f..a0ffe85a 100644 --- a/Documentation/diffcore.txt +++ b/Documentation/diffcore.txt @@ -6,7 +6,7 @@ June 2005 Introduction ------------ -The diff commands git-diff-cache, git-diff-files, and +The diff commands git-diff-index, git-diff-files, and git-diff-tree can be told to manipulate differences they find in unconventional ways before showing diff(1) output. The manipulation is collectively called "diffcore transformation". @@ -21,9 +21,9 @@ The chain of operation The git-diff-* family works by first comparing two sets of files: - - git-diff-cache compares contents of a "tree" object and the - working directory (when --cached flag is not used) or a - "tree" object and the index file (when --cached flag is + - git-diff-index compares contents of a "tree" object and the + working directory (when '--cached' flag is not used) or a + "tree" object and the index file (when '--cached' flag is used); - git-diff-files compares contents of the index file and the @@ -37,29 +37,31 @@ comparison is passed from these commands to what is internally called "diffcore", in a format similar to what is output when the -p option is not used. E.g. - in-place edit :100644 100644 bcd1234... 0123456... M file0 - create :000000 100644 0000000... 1234567... N file4 - delete :100644 000000 1234567... 0000000... D file5 - unmerged :000000 000000 0000000... 0000000... U file6 +------------------------------------------------ +in-place edit :100644 100644 bcd1234... 0123456... M file0 +create :000000 100644 0000000... 1234567... A file4 +delete :100644 000000 1234567... 0000000... D file5 +unmerged :000000 000000 0000000... 0000000... U file6 +------------------------------------------------ The diffcore mechanism is fed a list of such comparison results (each of which is called "filepair", although at this point each of them talks about a single file), and transforms such a list into another list. There are currently 6 such transformations: - - diffcore-pathspec - - diffcore-break - - diffcore-rename - - diffcore-merge-broken - - diffcore-pickaxe - - diffcore-order +- diffcore-pathspec +- diffcore-break +- diffcore-rename +- diffcore-merge-broken +- diffcore-pickaxe +- diffcore-order -These are applied in sequence. The set of filepairs git-diff-* +These are applied in sequence. The set of filepairs git-diff-\* commands find are used as the input to diffcore-pathspec, and the output from diffcore-pathspec is used as the input to the next transformation. The final result is then passed to the output routine and generates either diff-raw format (see Output -format sections of the manual for git-diff-* commands) or +format sections of the manual for git-diff-\* commands) or diff-patch format. @@ -87,13 +89,17 @@ used to detect a filepair that represents "complete rewrite" and break such filepair into two filepairs that represent delete and create. E.g. If the input contained this filepair: - :100644 100644 bcd1234... 0123456... M file0 +------------------------------------------------ +:100644 100644 bcd1234... 0123456... M file0 +------------------------------------------------ and if it detects that the file "file0" is completely rewritten, it changes it to: - :100644 000000 bcd1234... 0000000... D file0 - :000000 100644 0000000... 0123456... N file0 +------------------------------------------------ +:100644 000000 bcd1234... 0000000... D file0 +:000000 100644 0000000... 0123456... A file0 +------------------------------------------------ For the purpose of breaking a filepair, diffcore-break examines the extent of changes between the contents of the files before @@ -117,14 +123,18 @@ controlled by the -M option (to detect renames) and the -C option (to detect copies as well) to the git-diff-* commands. If the input contained these filepairs: - :100644 000000 0123456... 0000000... D fileX - :000000 100644 0000000... 0123456... N file0 +------------------------------------------------ +:100644 000000 0123456... 0000000... D fileX +:000000 100644 0000000... 0123456... A file0 +------------------------------------------------ and the contents of the deleted file fileX is similar enough to the contents of the created file file0, then rename detection merges these filepairs and creates: - :100644 100644 0123456... 0123456... R100 fileX file0 +------------------------------------------------ +:100644 100644 0123456... 0123456... R100 fileX file0 +------------------------------------------------ When the "-C" option is used, the original contents of modified files and contents of unchanged files are considered as @@ -133,15 +143,19 @@ addition to the deleted files. If the input were like these filepairs, that talk about a modified file fileY and a newly created file file0: - :100644 100644 0123456... 1234567... M fileY - :000000 100644 0000000... 0123456... N file0 +------------------------------------------------ +:100644 100644 0123456... 1234567... M fileY +:000000 100644 0000000... 0123456... A file0 +------------------------------------------------ the original contents of fileY and the resulting contents of file0 are compared, and if they are similar enough, they are changed to: - :100644 100644 0123456... 1234567... M fileY - :100644 100644 0123456... 0123456... C100 fileY file0 +------------------------------------------------ +:100644 100644 0123456... 1234567... M fileY +:100644 100644 0123456... 0123456... C100 fileY file0 +------------------------------------------------ In both rename and copy detection, the same "extent of changes" algorithm used in diffcore-break is used to determine if two @@ -150,15 +164,13 @@ similarity score different from the default 50% by giving a number after "-M" or "-C" option (e.g. "-M8" to tell it to use 8/10 = 80%). -Note. When the "-C" option is used, git-diff-cache and -git-diff-file commands feed not just modified filepairs but -unmodified ones to diffcore mechanism as well. This lets the -copy detector consider unmodified files as copy source -candidates at the expense of making it slower. Currently -git-diff-tree does not feed unmodified filepairs even when the -"-C" option is used, so it can detect copies only if the file -that was copied happened to have been modified in the same -changeset. +Note. When the "-C" option is used with --find-copies-harder +option, git-diff-\* commands feed unmodified filepairs to +diffcore mechanism as well as modified ones. This lets the copy +detector consider unmodified files as copy source candidates at +the expense of making it slower. Without --find-copies-harder, +git-diff-\* commands can detect copies only if the file that was +copied happened to have been modified in the same changeset. diffcore-merge-broken @@ -188,10 +200,19 @@ material is deleted, the broken pairs are merged back into a single modification) by giving a second number to -B option, like these: - -B50/60 (give 50% "break score" to diffcore-break, use - 60% for diffcore-merge-broken). - -B/60 (the same as above, since diffcore-break defautls to - 50%). +* -B50/60 (give 50% "break score" to diffcore-break, use 60% + for diffcore-merge-broken). + +* -B/60 (the same as above, since diffcore-break defaults to 50%). + +Note that earlier implementation left a broken pair as a separate +creation and deletion patches. This was unnecessary hack and +the latest implementation always merges all the broken pairs +back into modifications, but the resulting patch output is +formatted differently to still let the reviewing easier for such +a complete rewrite by showing the entire contents of old version +prefixed with '-', followed by the entire contents of new +version prefixed with '+'. diffcore-pickaxe @@ -230,12 +251,14 @@ in the file are output before ones that match a later line, and filepairs that do not match any glob pattern are output last. As an example, typical orderfile for the core GIT probably -should look like this: +would look like this: +------------------------------------------------ README Makefile Documentation *.h *.c t +------------------------------------------------