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Diffstat (limited to 'Documentation/gitdiffcore.txt')
| -rw-r--r-- | Documentation/gitdiffcore.txt | 106 |
1 files changed, 48 insertions, 58 deletions
diff --git a/Documentation/gitdiffcore.txt b/Documentation/gitdiffcore.txt index 4d56c85260..daf1782a31 100644 --- a/Documentation/gitdiffcore.txt +++ b/Documentation/gitdiffcore.txt @@ -3,44 +3,59 @@ gitdiffcore(7) NAME ---- -gitdiffcore - Tweaking diff output (June 2005) +gitdiffcore - Tweaking diff output SYNOPSIS -------- -git diff * +[verse] +'git diff' * DESCRIPTION ----------- -The diff commands git-diff-index, git-diff-files, and git-diff-tree +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 +unconventional ways before showing 'diff' output. The manipulation is collectively called "diffcore transformation". This short note -describes what they are and how to use them to produce diff outputs -that are easier to understand than the conventional kind. +describes what they are and how to use them to produce 'diff' output +that is easier to understand than the conventional kind. The chain of operation ---------------------- -The git-diff-* family works by first comparing two sets of +The 'git diff-{asterisk}' family works by first comparing two sets of files: - - git-diff-index compares contents of a "tree" object and the + - '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 + - 'git diff-files' compares contents of the index file and the working directory; - - git-diff-tree compares contents of two "tree" objects; + - 'git diff-tree' compares contents of two "tree" objects; -In all of these cases, the commands themselves compare -corresponding paths in the two sets of files. The result of -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 all of these cases, the commands themselves first optionally limit +the two sets of files by any pathspecs given on their command-lines, +and compare corresponding paths in the two resulting sets of files. + +The pathspecs are used to limit the world diff operates in. They remove +the filepairs outside the specified sets of pathnames. E.g. If the +input set of filepairs included: + +------------------------------------------------ +:100644 100644 bcd1234... 0123456... M junkfile +------------------------------------------------ + +but the command invocation was `git diff-files myfile`, then the +junkfile entry would be removed from the list because only "myfile" +is under consideration. + +The result of 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 @@ -52,53 +67,28 @@ 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: +into another list. There are currently 5 such transformations: -- diffcore-pathspec - diffcore-break - diffcore-rename - diffcore-merge-broken - diffcore-pickaxe - diffcore-order -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 +These are applied in sequence. The set of filepairs 'git diff-{asterisk}' +commands find are used as the input to diffcore-break, and +the output from diffcore-break 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-{asterisk}' commands) or diff-patch format. -diffcore-pathspec: For Ignoring Files Outside Our Consideration ---------------------------------------------------------------- - -The first transformation in the chain is diffcore-pathspec, and -is controlled by giving the pathname parameters to the -git-diff-* commands on the command line. The pathspec is used -to limit the world diff operates in. It removes the filepairs -outside the specified set of pathnames. E.g. If the input set -of filepairs included: - ------------------------------------------------- -:100644 100644 bcd1234... 0123456... M junkfile ------------------------------------------------- - -but the command invocation was "git-diff-files myfile", then the -junkfile entry would be removed from the list because only "myfile" -is under consideration. - -Implementation note. For performance reasons, git-diff-tree -uses the pathname parameters on the command line to cull set of -filepairs it feeds the diffcore mechanism itself, and does not -use diffcore-pathspec, but the end result is the same. - - diffcore-break: For Splitting Up "Complete Rewrites" ---------------------------------------------------- The second transformation in the chain is diffcore-break, and is -controlled by the -B option to the git-diff-* commands. This is +controlled by the -B option to the 'git diff-{asterisk}' commands. This is 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: @@ -134,7 +124,7 @@ diffcore-rename: For Detection Renames and Copies This transformation is used to detect renames and copies, and is controlled by the -M option (to detect renames) and the -C option -(to detect copies as well) to the git-diff-* commands. If the +(to detect copies as well) to the 'git diff-{asterisk}' commands. If the input contained these filepairs: ------------------------------------------------ @@ -178,12 +168,12 @@ a similarity score different from the default of 50% by giving a number after the "-M" or "-C" option (e.g. "-M8" to tell it to use 8/10 = 80%). -Note. When the "-C" option is used with `\--find-copies-harder` -option, git-diff-\* commands feed unmodified filepairs to +Note. When the "-C" option is used with `--find-copies-harder` +option, 'git diff-{asterisk}' 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 +the expense of making it slower. Without `--find-copies-harder`, +'git diff-{asterisk}' commands can detect copies only if the file that was copied happened to have been modified in the same changeset. @@ -234,18 +224,18 @@ 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-* +-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 "original" side has the specified string and -whose "result" side does not. Such a filepair represents "the -string appeared in this changeset". It also checks for the +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 +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 +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 @@ -257,7 +247,7 @@ diffcore-order: For Sorting the Output Based on Filenames This is used to reorder the filepairs according to the user's (or project's) taste, and is controlled by the -O option to the -git-diff-* commands. +'git diff-{asterisk}' commands. This takes a text file each of whose lines is a shell glob pattern. Filepairs that match a glob pattern on an earlier line |