This attempts to optimize "diff-tree -[CM] --stdin", which
compares successible tree pairs.  This optimization does not
make much sense for other commands in the diff-* brothers.

When reading from --stdin and using rename/copy detection, the
patch makes diff-tree to read the current index file first.
This is done to reuse the optimization used by diff-cache in the
non-cached case.  Similarity estimator can avoid expanding a
blob if the index says what is in the work tree has an exact
copy of that blob already expanded.

Another optimization the patch makes is to check only file sizes
first to terminate similarity estimation early.  In order for
this to work, it needs a way to tell the size of the blob
without expanding it.  Since an obvious way of doing it, which
is to keep all the blobs previously used in the memory, is too
costly, it does so by keeping the filesize for each object it
has already seen in memory.
Signed-off-by: NJunio C Hamano <junkio@cox.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

When --pickaxe-all is given in addition to -S, pickaxe shows the
entire diffs contained in the changeset, not just the diffs for
the filepair that touched the sought-after string.  This is
useful to see the changes in context.
Signed-off-by: NJunio C Hamano <junkio@cox.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This changes the argument of diff_setup() from an integer that
says if we are feeding reversed diff to a bitmask, so that later
global options can be added more easily.
Signed-off-by: NJunio C Hamano <junkio@cox.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

For later stages to reorder patches, pruning logic and rename detection
logic should not decide which delete to discard (because another entry
said it will take over the file as a rename) until the very end.

Also fix some tests that were assuming the earlier "last one is rename
or keep everything else is copy" semantics of diff-raw format, which no
longer is true.
Signed-off-by: NJunio C Hamano <junkio@cox.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This changes the diff-raw format again, following the mailing
list discussion.  The new format explicitly expresses which one
is a rename and which one is a copy.

The documentation and tests are updated to match this change.
Signed-off-by: NJunio C Hamano <junkio@cox.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This moves the path selection logic from individual programs to a new
diffcore transformer (diff-tree still needs to have its own for
performance reasons).  Also the header printing code in diff-tree was
tweaked not to produce anything when pickaxe is in effect and there is
nothing interesting to report.  An interesting example is the following
in the GIT archive itself:

    $ git-whatchanged -p -C -S'or something in a real script'
Signed-off-by: NJunio C Hamano <junkio@cox.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Update the diff-raw format as Linus and I discussed, except that
it does not use sequence of underscore '_' letters to express
nonexistence.  All '0' mode is used for that purpose instead.

The new diff-raw format can express rename/copy, and the earlier
restriction that -M and -C _must_ be used with the patch format
output is no longer necessary.  The patch makes -M and -C flags
independent of -p flag, so you need to say git-whatchanged -M -p
to get the diff/patch format.

Updated are both documentations and tests.
Signed-off-by: NJunio C Hamano <junkio@cox.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This does not actually supress the extra headers when pickaxe is
used, but prepares enough support for diff-tree to implement it.
Signed-off-by: NJunio C Hamano <junkio@cox.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Constness fix for pickaxe option.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This steals the "pickaxe" feature from JIT and make it available
to the bare Plumbing layer.  From the command line, the user
gives a string he is intersted in.

Using the diff-core infrastructure previously introduced, it
filters the differences to limit the output only to the diffs
between <src> and <dst> where the string appears only in one but
not in the other.  For example:

 $ ./git-rev-list HEAD | ./git-diff-tree -Sdiff-tree-helper --stdin -M

would show the diffs that touch the string "diff-tree-helper".

In real software-archaeologist application, you would typically
look for a few to several lines of code and see where that code
came from.

The "pickaxe" module runs after "rename/copy detection" module,
so it even crosses the file rename boundary, as the above
example demonstrates.
Signed-off-by: NJunio C Hamano <junkio@cox.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This cleans up the way calls are made into the diff core from diff-tree
family and diff-helper.  Earlier, these programs had "if
(generating_patch)" sprinkled all over the place, but those ugliness are
gone and handled uniformly from the diff core, even when not generating
patch format.

This also allowed diff-cache and diff-files to acquire -R
(reverse) option to generate diff in reverse.  Users of
diff-tree can swap two trees easily so I did not add -R there.

[ Linus' note: I'll add -R to "diff-tree" too, since a "commit
  diff" doesn't have another tree to switch around: the other
  tree is always the parent(s) of the commit ]

Also -M<digits-as-mantissa> suggestion made by Linus has been
implemented.

Documentation updates are also included.
Signed-off-by: NJunio C Hamano <junkio@cox.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This rips out the rename detection engine from diff-helper and moves it
to the diff core, and updates the internal calling convention used by
diff-tree family into the diff core.  In order to give the same option
name to diff-tree family as well as to diff-helper, I've changed the
earlier diff-helper '-r' option to '-M' (stands for Move; sorry but the
natural abbreviation 'r' for 'rename' is already taken for 'recursive').

Although I did a fair amount of test with the git-diff-tree with
existing rename commits in the core GIT repository, this should still be
considered beta (preview) release.  This patch depends on the diff-delta
infrastructure just committed.

This implements almost everything I wanted to see in this series of
patch, except a few minor cleanups in the calling convention into diff
core, but that will be a separate cleanup patch.
Signed-off-by: NJunio C Hamano <junkio@cox.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch adds a framework and a stub implementation of rename
detection to diff-helper program.

The current stub code is just enough to detect pure renames in
diff-tree output and not fancier.  The plan is perhaps to use
the same delta code when Nico's delta storage patch is merged
for similarity evaluation purposes.
Signed-off-by: NJunio C Hamano <junkio@cox.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

It used to be that diff-tree needed helper support to parse its
raw output to generate diffs, but these days git-diff-* family
produces the same output and the helper is not tied to diff-tree
anymore.  Drop "tree" from its name.

This commit is done separately to record just the rename and no
file content changes. The changes in the renamed files are recorded
in the next commit.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Bundled with the changes in the unrenamed files.
Signed-off-by: NPetr Baudis <pasky@ucw.cz>

This patch optimizes "diff-cache -p --cached" by avoiding to
inflate blobs into temporary files when the blob recorded in the
cache matches the corresponding file in the work tree.  The file
in the work tree is passed as the comparison source in such a
case instead.

This optimization kicks in only when we have already read the
cache this optimization and this is deliberate.  Especially,
diff-tree does not use this code, because changes are contained
in small number of files relative to the project size most of
the time, and reading cache is so expensive for a large project
that the cost of reading it outweighs the savings by not
inflating blobs.

Also this patch cleans up the structure passed from diff clients
by removing one unused structure member.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This introduces three public functions for diff-cache and friends can
use to call out to the GIT_EXTERNAL_DIFF program when they wish to.

A normal "add/remove/change" entry is turned into 7-parameter process
invocation of GIT_EXTERNAL_DIFF program as before.  In addition, the
program can now be called with a single parameter when diff-cache and
friends want to report an unmerged path. 
Signed-off-by: NJunio C Hamano <junkio@cox.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This reworks the diff-tree-helper and show-diff to further make external
diff command interface simpler.

These commands now honor GIT_EXTERNAL_DIFF environment variable which
can point at an arbitrary program that takes 7 parameters:

  name file1 file1-sha1 file1-mode file2 file2-sha1 file2-mode

The parameters for an external diff command are as follows:

  name        this invocation of the command is to emit diff
	      for the named cache/tree entry.

  file1       pathname that holds the contents of the first
	      file.  This can be a file inside the working
	      tree, or a temporary file created from the blob
	      object, or /dev/null.  The command should not
	      attempt to unlink it -- the temporary is
	      unlinked by the caller.

  file1-sha1  sha1 hash if file1 is a blob object, or "."
	      otherwise.

  file1-mode  mode bits for file1, or "." for a deleted file.

If GIT_EXTERNAL_DIFF environment variable is not set, the
default is to invoke diff with the set of parameters old
show-diff used to use.  This built-in implementation honors the
GIT_DIFF_CMD and GIT_DIFF_OPTS environment variables as before.
Signed-off-by: NJunio C Hamano <junkio@cox.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

With this patch, the non-core'ish part of show-diff command that
invokes an external "diff" comand to obtain patches is split
into a separate file.  The next patch will introduce a new
command, diff-tree-helper, which uses this common diff interface
to format diff-tree and diff-cache output into a patch form.
Signed-off-by: NJunio C Hamano <junkio@cox.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>