Translate parse_git_branch function to zsh from bash (for prompt)

Question

I am using this function in Bash

function parse_git_branch {
  git_status="$(git status 2> /dev/null)"
  pattern="^# On branch ([^${IFS}]*)"
  if [[ ! ${git_status}} =~ "working directory clean" ]]; then
    state="*"
  fi
  # add an else if or two here if you want to get more specific

  if [[ ${git_status} =~ ${pattern} ]]; then
    branch=${BASH_REMATCH[1]}
    echo "(${branch}${state})"
  fi
}

but I'm determined to use zsh. While I can use this perfectly as a shell script (even without a shebang) in my .zshrc the error is a parse error on this line if [[ ! ${git_status}}...

What do I need to do to get it ready for zshell?

Edit: The "actual error" I'm getting is " parse error near } and it refers to the line with the strange double }}, which works on Bash.

Edit: Here's the final code, just for fun:

parse_git_branch() {
    git_status="$(git status 2> /dev/null)"
pattern="^# On branch ([^[:space:]]*)"
    if [[ ! ${git_status} =~ "working directory clean" ]]; then
        state="*"
    fi
    if [[ ${git_status} =~ ${pattern} ]]; then
      branch=${match[1]}
      echo "(${branch}${state})"
    fi
}

setopt PROMPT_SUBST
PROMPT='$PR_GREEN%n@$PR_GREEN%m%u$PR_NO_COLOR:$PR_BLUE%2c$PR_NO_COLOR%(!.#.$)'
RPROMPT='$PR_GREEN$(parse_git_branch)$PR_NO_COLOR'

Thanks to everybody for your patience and help.

Edit: The best answer has schooled us all: git status is porcelain (UI). Good scripting goes against GIT plumbing. Here's the final function:

# The latest version of Chris' function below

PROMPT='$PR_GREEN%n@$PR_GREEN%m%u$PR_NO_COLOR:$PR_BLUE%2c$PR_NO_COLOR%(!.#.$)'
RPROMPT='$PR_GREEN$(parse_git_branch)$PR_NO_COLOR'

Note that only the prompt is zsh-specific. In Bash it would be your prompt plus "\$(parse_git_branch)".

This might be slower (more calls to GIT, but that's an empirical question) but it won't be broken by changes in GIT (they don't change the plumbing). And that is very important for a good script moving forward.

Answer 1

Get rid of the extra }? ${git_status}} should be ${git_status}.

---

Once the extra } is removed, the only potential issue that I see is the use of ${BASH_REMATCH[1]}. You can use that in zsh, but it requires enabling the option to do so. As zsh docs on conditional expressions show, you would need to use something like

if [[ ${git_status} =~ ${pattern} ]]; then
  branch=${match[1]}
  echo "(${branch}${state})"
fi

Answer 2

May be this zsh Git repository will contain Tests which can give you some clue:

• A01grammar.ztst
• A07control.ztst

Answer 3

If you don't want to learn zsh, I'd suggest you to use another language, like Python, for that kind of parsing.

Check out the git status Python parser and the zsh-git-prompt project on github to see how to get a nice zsh prompt for git.

Answer 4

If you are getting error failed to compile regex: illegal byte sequence then remove NULL from IFS. (Replace ${IFS} with ${IFS//$'\0'/}).

Answer 5

You can use the array match instead of $BASH_REMATCH. You can also escape the extra closing curly brace.

Untested:

function parse_git_branch {
  git_status="$(git status 2> /dev/null)"
  pattern="^# On branch ([^${IFS}]*)"
  if [[ ! ${git_status}\} =~ "working directory clean" ]]; then
    state="*"
  fi
  # add an else if or two here if you want to get more specific

  if [[ ${git_status} =~ ${pattern} ]]; then
    branch=${match[1]}
    echo "(${branch}${state})"
  fi
}

Give that a try and see if it helps.

Answer 6

You should really use Git “plumbing” commands to extract the info you want. The output from the “porcelain” commands (e.g.git status) may change over time, but the behavior of the “plumbing” commands is much more stable.

With the porcelain interfaces, it can also be done without “bashisms” or “zshisms” (i.e. the =~ matching operator):

parse_git_branch() {
    in_wd="$(git rev-parse --is-inside-work-tree 2>/dev/null)" || return
    test "$in_wd" = true || return
    state=''
    git update-index --refresh -q >/dev/null # avoid false positives with diff-index
    if git rev-parse --verify HEAD >/dev/null 2>&1; then
        git diff-index HEAD --quiet 2>/dev/null || state='*'
    else
        state='#'
    fi
    (
        d="$(git rev-parse --show-cdup)" &&
        cd "$d" &&
        test -z "$(git ls-files --others --exclude-standard .)"
    ) >/dev/null 2>&1 || state="${state}+"
    branch="$(git symbolic-ref HEAD 2>/dev/null)"
    test -z "$branch" && branch='<detached-HEAD>'
    echo "${branch#refs/heads/}${state}"
}

Integrating the output into the prompt is still shell specific (i.e. escape or quote the $ (for both bash and zsh) and set PROMPT_SUBST (for zsh)).