Git checkout alias that accepts regular expressions

.gitconfig

[alias]
  co = !"find_and_checkout_branch(){\
    for last; do true; done ; \
    pattern='^/.*/$' ;\
    if [[ $# -eq 1 && $last =~ $pattern ]] ;\
    then \
      branch_pattern=`echo $last | sed -e 's/^\\///' -e 's/\\/$//'` ;\
      branch=`git for-each-ref --sort=-committerdate --format='%(refname:short)' refs/heads/ | grep -E -i $branch_pattern | head -n1` ;\
      if [[ $branch ]] ; then \
        git checkout $branch ;\
      else \
        echo "No local branch found matching $branch_pattern. Checking remote branches." ; \
        branch=`git for-each-ref --sort=-committerdate --format='%(refname:short)' refs/remotes/ | grep -E -i $branch_pattern | head -n1 | sed -e 's|origin/||'` ;\
        if [[ $branch ]] ; then \
            echo "Found $branch. Open it now? [y]/n: " ;\
            exec < /dev/tty ;\
            read response ;\
            if [ -z "$response" ] || [ "$response" = "y" ] ; then \
                echo "git checkout $branch" ; \
                git checkout $branch ; \
            fi ;\
        else \
            echo "No remote branch found matching $branch_pattern." ; \
        fi \
      fi \
    else \
      git checkout $@ ;\
    fi \
  } ; find_and_checkout_branch"

a.md

The below co alias allows you to pass in a basic regular expression (specified by a leading and ending /) for checking out a recently worked on branch. If no local branch is found it searches the remote branches and prints a prompt to confirm a possible match. If the given branch name isn't a regex it falls back to normal checkout behavior.

Example

With regex:

git co /cool-feature/
Switched to branch 'spike/1234/cool-feature'

With regex, only matching a remote branch:

git co /cool-feature/
No local branch found matching cool-feature. Checking remote branches.
Found spike/1234/cool-feature. Open it now? [y]/n:

git checkout spike/1234/cool-feature
Branch spike/1234/cool-feature set up to track remote branch spike/1234/cool-feature from origin
Switched to a new branch 'spike/1234/cool-feature'

With regex, no matching branch:

git co /non-existent/
No local branch found matching non-existent. Checking remote branches.
No remote branch found matching non-existent.

Without regex:

git co spike/1234/cool-feature

It works as expected (at least how I expect it to work) with multiple arguments:

git co -b my-new-branch-here
git co -b my-new-branch-here parent-branch-here

If you provide more than one argument it doesn't use regular expression matching.

For convenience it helps to set up a function to call the alias. For example for Bash in ~/.bash_aliases, which allows to simply call gco branch_pattern to check out the given branch.

gco() {
    if [[ ! -z "$1" ]]; then
        git co "/$1/"
    fi
}