starship/src/init/starship.zsh

# ZSH has a quirk where `preexec` is only run if a command is actually run (i.e
# pressing ENTER at an empty command line will not cause preexec to fire). This
# can cause timing issues, as a user who presses "ENTER" without running a command
# will see the time to the start of the last command, which may be very large.

# To fix this, we create STARSHIP_START_TIME upon preexec() firing, and destroy it
# after drawing the prompt. This ensures that the timing for one command is only
# ever drawn once (for the prompt immediately after it is run).

zmodload zsh/parameter  # Needed to access jobstates variable for NUM_JOBS

starship_render() {
    # Use length of jobstates array as number of jobs. Expansion fails inside
    # quotes so we set it here and then use the value later on.
    NUM_JOBS=$#jobstates
    PROMPT="$(::STARSHIP:: prompt --keymap="${KEYMAP-}" --status=$STATUS --cmd-duration=${STARSHIP_DURATION-} --jobs="$NUM_JOBS")"
}

# Will be run before every prompt draw
starship_precmd() {
    # Save the status, because commands in this pipeline will change $?
    STATUS=$?

    # Compute cmd_duration, if we have a time to consume, otherwise clear the
    # previous duration
    if [[ -n "${STARSHIP_START_TIME+1}" ]]; then
        STARSHIP_END_TIME=$(::STARSHIP:: time)
        STARSHIP_DURATION=$((STARSHIP_END_TIME - STARSHIP_START_TIME))
        unset STARSHIP_START_TIME
    else
        unset STARSHIP_DURATION
    fi

    # Render the updated prompt
    starship_render
}
starship_preexec() {
    STARSHIP_START_TIME=$(::STARSHIP:: time)
}

# If precmd/preexec arrays are not already set, set them. If we don't do this,
# the code to detect whether starship_precmd is already in precmd_functions will
# fail because the array doesn't exist (and same for starship_preexec)
[[ -z "${precmd_functions+1}" ]] && precmd_functions=()
[[ -z "${preexec_functions+1}" ]] && preexec_functions=()

# If starship precmd/preexec functions are already hooked, don't double-hook them
# to avoid unnecessary performance degradation in nested shells
if [[ -z ${precmd_functions[(re)starship_precmd]} ]]; then
    precmd_functions+=(starship_precmd)
fi
if [[ -z ${preexec_function[(re)starship_preexec]} ]]; then
    preexec_functions+=(starship_preexec)
fi

# Set up a function to redraw the prompt if the user switches vi modes
zle-keymap-select() {
    starship_render
    zle reset-prompt
}

STARSHIP_START_TIME=$(::STARSHIP:: time)
zle -N zle-keymap-select
export STARSHIP_SHELL="zsh"