cg-switch

   1 #!/usr/bin/env bash
   2 #
   3 # Switch the working tree to a different (or new) local branch
   4 # Copyright (c) Yann Dirson, Petr Baudis  2005
   5 #
   6 # `cg-switch` can switch your current local branch (and working copy)
   7 # to an existing branch, or create a new branch based on a given commit.
   8 #
   9 # Terminology note: This command concerns local branches (also called
  10 # "heads"), not remote branches (those managed by `cg-branch-add`).
  11 #
  12 # Note that `cg-switch` is meant for permanent switching of your current
  13 # local branch (permanent in the sense that you are going to work on it;
  14 # you can obviously `cg-switch` again later). If you want to just casually
  15 # explore the current state of a particular branch of commit, use `cg-seek`.
  16 #
  17 # OPTIONS
  18 # -------
  19 # -c:: Create new branch based on HEAD
  20 #       Create a new branch of given name, based on your current commit
  21 #       (HEAD). This option is equivalent to specifying '-r HEAD'. If
  22 #       '-f' is passed and the branch already exists, it is forcibly
  23 #       repointed to point to the current commit.
  24 #
  25 # -f:: Enable overwriting of existing branches
  26 #       Force the branch's head pointer to be updated to whatever you
  27 #       passed as the '-r' argument even if the branch already exists.
  28 #       WARNING: The pointer to the original contents of the branch will
  29 #       be lost! The contents itself will not be deleted right away,
  30 #       `git-fsck-objects --unreachable` might help you to find it.
  31 #       Besides, this can get very troublesome if you are pushing the
  32 #       branch out - please refer to the documentation of a close
  33 #       relative, `cg-admin-uncommit`.
  34 #
  35 # -l:: Preserve local changes in the branch
  36 #       If your working tree has uncommitted local changes, the default
  37 #       behaviour is that the changes will be reapplied to the new
  38 #       branch after switching. With this option, however, the local
  39 #       changes will be "kept" with your previous branch, you will
  40 #       get a pristine tree of the new branch and when you switch back
  41 #       to the original branch you will also get back the local changes.
  42 #       (You do not need to pass any special switches when switching
  43 #       back, '-l' has effect only on the branch you are switching _away_
  44 #       from.)
  45 #
  46 # -n:: No switch; only create and update the branch
  47 #       Do not switch your current branch to the given branch. This
  48 #       will make cg-switch to only create or update the branch, but
  49 #       leave your working copy alone.
  50 #
  51 # -o REMBRANCH:: Set the default remote branch for the branch
  52 #       Along switching the branches, this will also set the default
  53 #       remote branch to be associated with the target branch (used as
  54 #       default by e.g. `cg-update` and `cg-push`, falls back to 'origin').
  55 #       You may want to combine this with '-n' to change this for a branch
  56 #       other than the current one without actual switching. As a special
  57 #       present just for you, in case of '-o' the BRANCH `cg-switch` argument
  58 #       defaults to the current branch.
  59 #
  60 #       This setting is saved in Git configuration file under the key
  61 #       'branch.<name>.merge' and is understood by core Git as well.
  62 #
  63 # -p:: Do not touch the working copy
  64 #       Do not touch the working copy when switching. This _will_ switch
  65 #       your current branch, but the checked out working copy will have
  66 #       the original contents kept (so further `cg-diff` will list a lot
  67 #       of changes, relative to the new branch).
  68 #
  69 # -r COMMIT_ID:: Branch off the given COMMIT_ID, create branch if non-existing
  70 #       Point the branch at the given commit. Required when creating
  71 #       a new branch. When switching to an existing branch, the branch
  72 #       pointer is modified if '-r' is passed and confirmed by '-f'.
  73 #
  74 # EXAMPLE USAGE
  75 # -------------
  76 # To create a "v1.x" branch based on the commit "v1.0" and switch the
  77 # working copy to it, making it your current branch, do:
  78 #
  79 #       $ cg-switch -r v1.0 v1.x
  80 #
  81 # If you want to create the branch (let's say based on the current
  82 # commit) but don't switch your working copy to it (so that your
  83 # current branch stays the same as before), do:
  84 #
  85 #       $ cg-switch -n -c v1.x
  86 #
  87 # If you want to go back to the 'master' branch, just do:
  88 #
  89 #       $ cg-switch master
  90 #
  91 # To change the "v1.x" branch to refer to the latest commit on the
  92 # "testing" branch, do (WARNING: you will lose the pointer to the
  93 # original contents of the "v1.x" branch, be careful!):
  94 #
  95 #       $ cg-switch -f -r testing v1.x
  96
  97 # Testsuite: TODO
  98
  99 USAGE="cg-switch [-f] [-l | -n | -p] [-o REMBRANCH] [-c | -r COMMIT_ID] BRANCH"
 100 _git_requires_root=1
 101 _git_wc_unneeded=1
 102
 103 . "${COGITO_LIB}"cg-Xlib || exit 1
 104
 105 set -e
 106
 107
 108 repoint_head() {
 109         # $oldcommit is optional
 110         local dsthead="$1" dstcommit="$2" oldcommit="$3"
 111         git-update-ref "refs/heads/$dsthead" "$dstcommit" $oldcommit
 112 }
 113
 114
 115 force=
 116 savelocal=
 117 seek=1
 118 dstcommit=
 119 roll=1
 120 origin=
 121 while optparse; do
 122         if optparse -f; then
 123                 force=1
 124         elif optparse -l; then
 125                 savelocal=1
 126         elif optparse -n; then
 127                 seek=
 128         elif optparse -o=; then
 129                 origin="$OPTARG"
 130         elif optparse -p; then
 131                 roll=
 132         elif optparse -r=; then
 133                 dstcommit="$(cg-object-id -c "$OPTARG")" || exit 1
 134         elif optparse -c; then
 135                 dstcommit="$(cg-object-id -c)" || exit 1
 136         else
 137                 optfail
 138         fi
 139 done
 140
 141 [ "$origin" -o "${#ARGS[@]}" -eq "1" ] || usage
 142 [ "$seek$roll" = "" ] && usage
 143 [ "$savelocal" = "1" -a "$seek$roll" != "11" ] && usage
 144
 145 [ "$_git_no_wc" ] && [ "$seek" ] &&
 146         die "only cg-switch -n allowed outside a working copy"
 147
 148 if [ "${#ARGS[@]}" -gt 0 ]; then
 149         dsthead="${ARGS[0]}"
 150 else
 151         dsthead="$_git_head"
 152 fi
 153 [ -s "$_git/branches/$dsthead" ] &&
 154         die "refusing to switch to a remote branch - see README for lengthy explanation; use cg-seek to just quickly inspect it"
 155
 156 if [ "$seek" -a "$dsthead" != "$_git_head" ]; then
 157         [ -s "$_git/blocked" ] && die "switch blocked: $(cat "$_git/blocked")"
 158 fi
 159
 160
 161 if [ "$origin" ]; then
 162         [ -s "$_git/branches/$origin" ] ||
 163                 die "$origin is not a valid remote branch"
 164         echo "Setting $dsthead's origin: $origin"
 165         git-repo-config "branch.$dsthead.merge" "refs/heads/$origin" || exit 1
 166 fi
 167
 168
 169 if ! [ "$(git-symbolic-ref HEAD)" != "refs/heads/$dsthead" -o -n "$dstcommit" ]; then
 170         if [ "$origin" ]; then
 171                 exit 0
 172         else
 173                 die "already on branch $dsthead"
 174         fi
 175 fi
 176
 177
 178 curcommit="$(cg-object-id -c)"
 179
 180 if exists_ref "refs/heads/$dsthead"; then
 181         # Existing branch
 182         if [ -n "$dstcommit" ]; then
 183                 [ "$force" ] ||
 184                         die "branch $dsthead already exists - use -f to force the switch"
 185                 srccommit="$(cg-object-id -c "$dsthead")"
 186                 echo "Repointing branch $dsthead: $srccommit -> $dstcommit"
 187                 repoint_head "$dsthead" "$dstcommit" "$srccommit"
 188         fi
 189
 190 else
 191         # New branch
 192         [ "$dstcommit" ] || die "branch $dsthead does not exist - you must pass -r if you want to create a new branch"
 193         echo "Creating new branch $dsthead: $dstcommit"
 194         repoint_head "$dsthead" "$dstcommit"
 195 fi
 196
 197
 198 if [ "$seek" ]; then
 199         [ -n "$dstcommit" ] || dstcommit="$(cg-object-id -c "$dsthead")"
 200         if [ "$roll" ] && [ "x$curcommit" != "x$dstcommit" ]; then
 201                 # Shelve local changes
 202                 if [ "$savelocal" ]; then
 203                         echo "Saving local changes..."
 204                         shelve_changes # Sets $curcommit
 205                 fi
 206
 207                 echo "Switching to branch $dsthead..."
 208                 if ! tree_timewarp --no-head-update "along" "please rollback" "$curcommit" "$dstcommit"; then
 209                         abort_shelve "$curcommit"
 210                         exit 1
 211                 fi
 212
 213                 export _git_head="$dsthead"
 214                 unshelve_changes # Eats $dstcommit
 215         else
 216                 # Shelve local changes
 217                 if [ "$savelocal" ]; then
 218                         echo "Saving local changes..."
 219                         shelve_changes # Sets $curcommit
 220                 fi
 221
 222                 echo "Switching to branch $dsthead..."
 223
 224                 export _git_head="$dsthead"
 225                 unshelve_changes # Eats $dstcommit
 226         fi
 227         git-symbolic-ref HEAD "refs/heads/$dsthead"
 228 fi