Re: [PATCH] git-prompt.sh: shorter equal upstream branch name

On 2014-09-30 11:36, Julien Carsique wrote:

From: Julien Carsique <redacted>

When using the "name" option of GIT_PS1_SHOWUPSTREAM to show the upstream
abbrev name, if the upstream name is the same as the local name, then some
space could be saved in the prompt. This is especially needed on long branch
names.

Replace the upstream name with the sign '=' if equal to the local one.
Example:    [master * u= origin/=]$
instead of: [master * u= origin/master]$

Seems like a good idea to me.

Signed-off-by: Julien Carsique <redacted>
---
 contrib/completion/git-prompt.sh | 7 +++++++
 1 file changed, 7 insertions(+)

Please add some new tests in t/9903-bash-prompt.sh.  In particular:
  * upstream ref in refs/heads
  * upstream is git-svn
  * branch names containing slashes

To avoid colliding with other stuff, this variable should either be
local or prefixed with '__git_ps1'.

+			if [ "$__head" = "${__git_ps1_upstream_name##*/}" ]; then

This comparison breaks on branches containing a slash (e.g., foo/bar).

Also, how does this interact with git-svn?  (I don't use git-svn so I'm
not very familiar with how it manages refs.)

Assuming remote names can't contain a slash (which I think is true), a
safer approach might be parse the full ref and special-case refs/remotes:

    __git_ps1_upstream_name=$(git rev-parse \
        --abbrev-ref "${upstream}" 2>/dev/null)
    local tmp
    tmp=$(git rev-parse --symbolic-full-name "${upstream}" 2>/dev/null)
    case ${tmp} in
    refs/remotes/*)
        # todo: can ${b} be something other than refs/heads/* here?
        [ "${__git_ps1_upstream_name#*/}" != "${b#refs/heads/}" ] \
            || __git_ps1_upstream_name=${__git_ps1_upstream_name%%/*}/\=
        ;;
    esac

Additional cases could be added to handle git-svn if needed.

+				__git_ps1_upstream_name=${__git_ps1_upstream_name/$__head/=}

  * This could break if ${__head} contains any pattern-special
    characters.

  * While this syntax works in both Bash and Zsh (assuming no
    pattern-special characters), my preference is to stick to POSIX[1]
    when possible.  For example, assuming the upstream name is
    always in refs/remotes (which is not true, but this is an example)
    and remote names can't contain a '/', you could do this:

        __git_ps1_upstream_name=${__git_ps1_upstream_name%%/*}/\=

  * I don't think the CodingGuidelines explicitly prohibit long lines
    for shell code, and this file already contains plenty of long
    lines, but I really dislike lines longer than 80 characters.

[1] http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html

+			fi
+			unset __head
+
 			if [ $pcmode = yes ] && [ $ps1_expanded = yes ]; then
 				p="$p \${__git_ps1_upstream_name}"
 			else

-Richard