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In asciidoc 7, backticks like `foo` produced a typographic
effect, but did not otherwise affect the syntax. In asciidoc
8, backticks introduce an "inline literal" inside which markup
is not interpreted. To keep compatibility with existing
documents, asciidoc 8 has a "no-inline-literal" attribute to
keep the old behavior. We enabled this so that the
documentation could be built on either version.
It has been several years now, and asciidoc 7 is no longer
in wide use. We can now decide whether or not we want
inline literals on their own merits, which are:
1. The source is much easier to read when the literal
contains punctuation. You can use `master~1` instead
of `master{tilde}1`.
2. They are less error-prone. Because of point (1), we
tend to make mistakes and forget the extra layer of
quoting.
This patch removes the no-inline-literal attribute from the
Makefile and converts every use of backticks in the
documentation to an inline literal (they must be cleaned up,
or the example above would literally show "{tilde}" in the
output).
Problematic sites were found by grepping for '`.*[{\\]' and
examined and fixed manually. The results were then verified
by comparing the output of "html2text" on the set of
generated html pages. Doing so revealed that in addition to
making the source more readable, this patch fixes several
formatting bugs:
- HTML rendering used the ellipsis character instead of
literal "..." in code examples (like "git log A...B")
- some code examples used the right-arrow character
instead of '->' because they failed to quote
- api-config.txt did not quote tilde, and the resulting
HTML contained a bogus snippet like:
<tt><sub></tt> foo <tt></sub>bar</tt>
which caused some parsers to choke and omit whole
sections of the page.
- git-commit.txt confused ``foo`` (backticks inside a
literal) with ``foo'' (matched double-quotes)
- mentions of `A U Thor <author@example.com>` used to
erroneously auto-generate a mailto footnote for
author@example.com
- the description of --word-diff=plain incorrectly showed
the output as "[-removed-] and {added}", not "{+added+}".
- using "prime" notation like:
commit `C` and its replacement `C'`
confused asciidoc into thinking that everything between
the first backtick and the final apostrophe were meant
to be inside matched quotes
- asciidoc got confused by the escaping of some of our
asterisks. In particular,
`credential.\*` and `credential.<url>.\*`
properly escaped the asterisk in the first case, but
literally passed through the backslash in the second
case.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
283 lines
11 KiB
Plaintext
283 lines
11 KiB
Plaintext
gitdiffcore(7)
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==============
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NAME
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----
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gitdiffcore - Tweaking diff output
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SYNOPSIS
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--------
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[verse]
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'git diff' *
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DESCRIPTION
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-----------
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The diff commands 'git diff-index', 'git diff-files', and 'git diff-tree'
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can be told to manipulate differences they find in
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unconventional ways before showing 'diff' output. The manipulation
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is collectively called "diffcore transformation". This short note
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describes what they are and how to use them to produce 'diff' output
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that is easier to understand than the conventional kind.
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The chain of operation
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----------------------
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The 'git diff-{asterisk}' family works by first comparing two sets of
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files:
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- 'git diff-index' compares contents of a "tree" object and the
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working directory (when '\--cached' flag is not used) or a
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"tree" object and the index file (when '\--cached' flag is
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used);
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- 'git diff-files' compares contents of the index file and the
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working directory;
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- 'git diff-tree' compares contents of two "tree" objects;
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In all of these cases, the commands themselves first optionally limit
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the two sets of files by any pathspecs given on their command-lines,
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and compare corresponding paths in the two resulting sets of files.
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The pathspecs are used to limit the world diff operates in. They remove
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the filepairs outside the specified sets of pathnames. E.g. If the
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input set of filepairs included:
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------------------------------------------------
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:100644 100644 bcd1234... 0123456... M junkfile
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------------------------------------------------
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but the command invocation was `git diff-files myfile`, then the
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junkfile entry would be removed from the list because only "myfile"
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is under consideration.
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The result of comparison is passed from these commands to what is
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internally called "diffcore", in a format similar to what is output
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when the -p option is not used. E.g.
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------------------------------------------------
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in-place edit :100644 100644 bcd1234... 0123456... M file0
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create :000000 100644 0000000... 1234567... A file4
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delete :100644 000000 1234567... 0000000... D file5
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unmerged :000000 000000 0000000... 0000000... U file6
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------------------------------------------------
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The diffcore mechanism is fed a list of such comparison results
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(each of which is called "filepair", although at this point each
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of them talks about a single file), and transforms such a list
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into another list. There are currently 5 such transformations:
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- diffcore-break
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- diffcore-rename
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- diffcore-merge-broken
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- diffcore-pickaxe
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- diffcore-order
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These are applied in sequence. The set of filepairs 'git diff-{asterisk}'
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commands find are used as the input to diffcore-break, and
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the output from diffcore-break is used as the input to the
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next transformation. The final result is then passed to the
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output routine and generates either diff-raw format (see Output
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format sections of the manual for 'git diff-{asterisk}' commands) or
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diff-patch format.
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diffcore-break: For Splitting Up "Complete Rewrites"
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----------------------------------------------------
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The second transformation in the chain is diffcore-break, and is
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controlled by the -B option to the 'git diff-{asterisk}' commands. This is
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used to detect a filepair that represents "complete rewrite" and
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break such filepair into two filepairs that represent delete and
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create. E.g. If the input contained this filepair:
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------------------------------------------------
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:100644 100644 bcd1234... 0123456... M file0
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------------------------------------------------
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and if it detects that the file "file0" is completely rewritten,
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it changes it to:
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------------------------------------------------
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:100644 000000 bcd1234... 0000000... D file0
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:000000 100644 0000000... 0123456... A file0
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------------------------------------------------
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For the purpose of breaking a filepair, diffcore-break examines
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the extent of changes between the contents of the files before
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and after modification (i.e. the contents that have "bcd1234..."
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and "0123456..." as their SHA1 content ID, in the above
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example). The amount of deletion of original contents and
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insertion of new material are added together, and if it exceeds
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the "break score", the filepair is broken into two. The break
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score defaults to 50% of the size of the smaller of the original
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and the result (i.e. if the edit shrinks the file, the size of
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the result is used; if the edit lengthens the file, the size of
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the original is used), and can be customized by giving a number
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after "-B" option (e.g. "-B75" to tell it to use 75%).
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diffcore-rename: For Detection Renames and Copies
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-------------------------------------------------
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This transformation is used to detect renames and copies, and is
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controlled by the -M option (to detect renames) and the -C option
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(to detect copies as well) to the 'git diff-{asterisk}' commands. If the
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input contained these filepairs:
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------------------------------------------------
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:100644 000000 0123456... 0000000... D fileX
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:000000 100644 0000000... 0123456... A file0
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------------------------------------------------
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and the contents of the deleted file fileX is similar enough to
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the contents of the created file file0, then rename detection
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merges these filepairs and creates:
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------------------------------------------------
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:100644 100644 0123456... 0123456... R100 fileX file0
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------------------------------------------------
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When the "-C" option is used, the original contents of modified files,
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and deleted files (and also unmodified files, if the
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"\--find-copies-harder" option is used) are considered as candidates
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of the source files in rename/copy operation. If the input were like
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these filepairs, that talk about a modified file fileY and a newly
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created file file0:
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------------------------------------------------
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:100644 100644 0123456... 1234567... M fileY
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:000000 100644 0000000... bcd3456... A file0
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------------------------------------------------
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the original contents of fileY and the resulting contents of
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file0 are compared, and if they are similar enough, they are
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changed to:
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------------------------------------------------
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:100644 100644 0123456... 1234567... M fileY
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:100644 100644 0123456... bcd3456... C100 fileY file0
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------------------------------------------------
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In both rename and copy detection, the same "extent of changes"
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algorithm used in diffcore-break is used to determine if two
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files are "similar enough", and can be customized to use
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a similarity score different from the default of 50% by giving a
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number after the "-M" or "-C" option (e.g. "-M8" to tell it to use
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8/10 = 80%).
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Note. When the "-C" option is used with `--find-copies-harder`
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option, 'git diff-{asterisk}' commands feed unmodified filepairs to
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diffcore mechanism as well as modified ones. This lets the copy
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detector consider unmodified files as copy source candidates at
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the expense of making it slower. Without `--find-copies-harder`,
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'git diff-{asterisk}' commands can detect copies only if the file that was
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copied happened to have been modified in the same changeset.
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diffcore-merge-broken: For Putting "Complete Rewrites" Back Together
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--------------------------------------------------------------------
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This transformation is used to merge filepairs broken by
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diffcore-break, and not transformed into rename/copy by
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diffcore-rename, back into a single modification. This always
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runs when diffcore-break is used.
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For the purpose of merging broken filepairs back, it uses a
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different "extent of changes" computation from the ones used by
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diffcore-break and diffcore-rename. It counts only the deletion
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from the original, and does not count insertion. If you removed
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only 10 lines from a 100-line document, even if you added 910
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new lines to make a new 1000-line document, you did not do a
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complete rewrite. diffcore-break breaks such a case in order to
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help diffcore-rename to consider such filepairs as candidate of
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rename/copy detection, but if filepairs broken that way were not
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matched with other filepairs to create rename/copy, then this
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transformation merges them back into the original
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"modification".
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The "extent of changes" parameter can be tweaked from the
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default 80% (that is, unless more than 80% of the original
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material is deleted, the broken pairs are merged back into a
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single modification) by giving a second number to -B option,
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like these:
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* -B50/60 (give 50% "break score" to diffcore-break, use 60%
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for diffcore-merge-broken).
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* -B/60 (the same as above, since diffcore-break defaults to 50%).
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Note that earlier implementation left a broken pair as a separate
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creation and deletion patches. This was an unnecessary hack and
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the latest implementation always merges all the broken pairs
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back into modifications, but the resulting patch output is
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formatted differently for easier review in case of such
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a complete rewrite by showing the entire contents of old version
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prefixed with '-', followed by the entire contents of new
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version prefixed with '+'.
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diffcore-pickaxe: For Detecting Addition/Deletion of Specified String
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---------------------------------------------------------------------
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This transformation is used to find filepairs that represent
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changes that touch a specified string, and is controlled by the
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-S option and the `--pickaxe-all` option to the 'git diff-*'
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commands.
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When diffcore-pickaxe is in use, it checks if there are
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filepairs whose "result" side and whose "origin" side have
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different number of specified string. Such a filepair represents
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"the string appeared in this changeset". It also checks for the
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opposite case that loses the specified string.
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When `--pickaxe-all` is not in effect, diffcore-pickaxe leaves
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only such filepairs that touch the specified string in its
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output. When `--pickaxe-all` is used, diffcore-pickaxe leaves all
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filepairs intact if there is such a filepair, or makes the
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output empty otherwise. The latter behaviour is designed to
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make reviewing of the changes in the context of the whole
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changeset easier.
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diffcore-order: For Sorting the Output Based on Filenames
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---------------------------------------------------------
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This is used to reorder the filepairs according to the user's
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(or project's) taste, and is controlled by the -O option to the
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'git diff-{asterisk}' commands.
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This takes a text file each of whose lines is a shell glob
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pattern. Filepairs that match a glob pattern on an earlier line
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in the file are output before ones that match a later line, and
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filepairs that do not match any glob pattern are output last.
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As an example, a typical orderfile for the core git probably
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would look like this:
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------------------------------------------------
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README
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Makefile
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Documentation
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*.h
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*.c
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t
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------------------------------------------------
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SEE ALSO
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--------
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linkgit:git-diff[1],
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linkgit:git-diff-files[1],
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linkgit:git-diff-index[1],
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linkgit:git-diff-tree[1],
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linkgit:git-format-patch[1],
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linkgit:git-log[1],
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linkgit:gitglossary[7],
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link:user-manual.html[The Git User's Manual]
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GIT
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---
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Part of the linkgit:git[1] suite.
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