git-identify-revision

   1 #!/bin/sh
   2
   3 # situation: work tree is unknown rev
   4 # arguments: git rev-list arguments
   5 # we now identify the one revision with least differences
   6
   7 usage()
   8 {
   9         echo "Usage: $0 [--cached] git-rev-list args..."
  10         echo
  11         echo "Example: $0 --all"
  12         echo "Compares current work tree to all revisions, and identifies the"
  13         echo "closest match."
  14         echo
  15         echo "Example: $0 --cached v1.0..HEAD"
  16         echo "Compares current work tree to all revisions between v1.0 and HEAD,"
  17         echo "and identifies the closest match."
  18 }
  19
  20 case "$1" in
  21         --cached)
  22                 use_worktree=false
  23                 shift
  24                 ;;
  25         --help|-h)
  26                 usage
  27                 exit 0
  28                 ;;
  29         *)
  30                 use_worktree=true
  31                 ;;
  32 esac
  33
  34 if [ $# = 0 ]; then
  35         usage >&2
  36         exit 1
  37 fi
  38
  39 diffopts="-M -C"
  40
  41 if $use_worktree; then
  42         echo >&2 "Saving index..."
  43         oldindex=`git write-tree`
  44         # set up resetting
  45         trap 'echo >&2 "Restoring index..."; git reset "$oldindex" .' EXIT
  46         trap 'exit 1' INT TERM
  47
  48         echo >&2 "Creating index..."
  49         git add -A
  50 fi
  51
  52 echo >&2 "Listing candidates..."
  53 allrevs=`git rev-list "$@"`
  54
  55 echo >&2 "Evaluating candidates..."
  56 bestrev=
  57 bestrevscore=
  58 for rev in $allrevs; do
  59         score=`git diff $diffopts --cached "$rev" | wc -l`
  60         if [ -z "$bestrevscore" ] || [ "$score" -lt "$bestrevscore" ]; then
  61                 echo >&2 "Improved to $rev (score: $score)"
  62                 bestrev=$rev
  63                 bestrevscore=$score
  64                 if [ $score -eq 0 ]; then
  65                         break
  66                 fi
  67         fi
  68 done
  69 echo >&2 "Done."
  70
  71 echo "$bestrev"
  72 git diff $diffopts --cached "$bestrev" >&2