The "diff" gitattribute is somewhat overloaded right now. It
can say one of three things:
1. this file is definitely binary, or definitely not
(i.e., diff or !diff)
2. this file should use an external diff engine (i.e.,
diff=foo, diff.foo.command = custom-script)
3. this file should use particular funcname patterns
(i.e., diff=foo, diff.foo.(x?)funcname = some-regex)
Most of the time, there is no conflict between these uses,
since using one implies that the other is irrelevant (e.g.,
an external diff engine will decide for itself whether the
file is binary).
However, there is at least one conflicting situation: there
is no way to say "use the regular rules to determine whether
this file is binary, but if we do diff it textually, use
this funcname pattern." That is, currently setting diff=foo
indicates that the file is definitely text.
This patch introduces a "binary" config option for a diff
driver, so that one can explicitly set diff.foo.binary. We
default this value to "don't know". That is, setting a diff
attribute to "foo" and using "diff.foo.funcname" will have
no effect on the binaryness of a file. To get the current
behavior, one can set diff.foo.binary to true.
This patch also has one additional advantage: it cleans up
the interface to the userdiff code a bit. Before, calling
code had to know more about whether attributes were false,
true, or unset to determine binaryness. Now that binaryness
is a property of a driver, we can represent these situations
just by passing back a driver struct.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Both sets of code assume that one specifies a diff profile
as a gitattribute via the "diff=foo" attribute. They then
pull information about that profile from the config as
diff.foo.*.
The code for each is currently completely separate from the
other, which has several disadvantages:
- there is duplication as we maintain code to create and
search the separate lists of external drivers and
funcname patterns
- it is difficult to add new profile options, since it is
unclear where they should go
- the code is difficult to follow, as we rely on the
"check if this file is binary" code to find the funcname
pattern as a side effect. This is the first step in
refactoring the binary-checking code.
This patch factors out these diff profiles into "userdiff"
drivers. A file with "diff=foo" uses the "foo" driver, which
is specified by a single struct.
Note that one major difference between the two pieces of
code is that the funcname patterns are always loaded,
whereas external drivers are loaded only for the "git diff"
porcelain; the new code takes care to retain that situation.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
