git wrapper: DWIM mistyped commands

This patch introduces a modified Damerau-Levenshtein algorithm into
Git's code base, and uses it with the following penalties to show some
similar commands when an unknown command was encountered:

	swap = 0, insertion = 1, substitution = 2, deletion = 4

A typical output would now look like this:

	$ git sm
	git: 'sm' is not a git-command. See 'git --help'.

	Did you mean one of these?
		am
		rm

The cut-off is at similarity rating 6, which was empirically determined
to give sensible results.

As a convenience, if there is only one candidate, Git continues under
the assumption that the user mistyped it.  Example:

	$ git reabse
	WARNING: You called a Git program named 'reabse', which does
	not exist.
	Continuing under the assumption that you meant 'rebase'
	[...]

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Alex Riesen <raa.lkml@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/Makefile b/Makefile
index bf400e64f3..3daa6dcdb0 100644
--- a/Makefile
+++ b/Makefile
@@ -358,6 +358,7 @@ LIB_H += graph.h
 LIB_H += grep.h
 LIB_H += hash.h
 LIB_H += help.h
+LIB_H += levenshtein.h
 LIB_H += list-objects.h
 LIB_H += ll-merge.h
 LIB_H += log-tree.h
@@ -433,6 +434,7 @@ LIB_OBJS += hash.o
 LIB_OBJS += help.o
 LIB_OBJS += ident.o
 LIB_OBJS += interpolate.o
+LIB_OBJS += levenshtein.o
 LIB_OBJS += list-objects.o
 LIB_OBJS += ll-merge.o
 LIB_OBJS += lockfile.o