Add git information to your ZSH prompt.

## chpwd_update_git_vars.sh
update_current_git_vars

## precmd_update_git_vars.sh
if [ -n "$__EXECUTED_GIT_COMMAND" ]; then
	update_current_git_vars
	unset __EXECUTED_GIT_COMMAND
fi

## preexec_update_git_vars.sh
case "$1" in
	git*)
	__EXECUTED_GIT_COMMAND=1
	;;
esac

## prompt_git_info.sh
if [ -n "$__CURRENT_GIT_BRANCH" ]; then
	local s="("
	s+="$__CURRENT_GIT_BRANCH"
	case "$__CURRENT_GIT_BRANCH_STATUS" in
		ahead)
		s+="↑"
		;;
		diverged)
		s+="↕"
		;;
		behind)
		s+="↓"
		;;
	esac
	if [ -n "$__CURRENT_GIT_BRANCH_IS_DIRTY" ]; then
		s+="⚡"
	fi
	s+=")"

	printf " %s%s" "%{${fg[yellow]}%}" $s
fi

## update_current_git_vars.sh
unset __CURRENT_GIT_BRANCH
unset __CURRENT_GIT_BRANCH_STATUS
unset __CURRENT_GIT_BRANCH_IS_DIRTY

local st="$(git status 2>/dev/null)"
if [[ -n "$st" ]]; then
	local -a arr
	arr=(${(f)st})

	if [[ $arr[1] =~ 'Not currently on any branch.' ]]; then
		__CURRENT_GIT_BRANCH='no-branch'
	else
		__CURRENT_GIT_BRANCH="${arr[1][(w)4]}";
	fi

	if [[ $arr[2] =~ 'Your branch is' ]]; then
		if [[ $arr[2] =~ 'ahead' ]]; then
			__CURRENT_GIT_BRANCH_STATUS='ahead'
		elif [[ $arr[2] =~ 'diverged' ]]; then
			__CURRENT_GIT_BRANCH_STATUS='diverged'
		else
			__CURRENT_GIT_BRANCH_STATUS='behind'
		fi
	fi

	if [[ ! $st =~ 'nothing to commit' ]]; then
		__CURRENT_GIT_BRANCH_IS_DIRTY='1'
	fi
fi

## zshrc.sh
# Initialize colors.
autoload -U colors
colors

# Allow for functions in the prompt.
setopt PROMPT_SUBST

# Autoload zsh functions.
fpath=(~/.zsh/functions $fpath)
autoload -U ~/.zsh/functions/*(:t)

# Enable auto-execution of functions.
typeset -ga preexec_functions
typeset -ga precmd_functions
typeset -ga chpwd_functions

# Append git functions needed for prompt.
preexec_functions+='preexec_update_git_vars'
precmd_functions+='precmd_update_git_vars'
chpwd_functions+='chpwd_update_git_vars'

# Set the prompt.
PROMPT=$'%{${fg[cyan]}%}%B%~%b$(prompt_git_info)%{${fg[default]}%} '