vim-session

#!/bin/bash -e

SESSION_FILE_DEFAULT="./session"

DBG=false
VIM=vim
while [ ${#} -gt 0 ]
do
    case "${1}" in
        --) shift 1; break;;
        -D) shift 1; DBG=true;;
        -e) shift 1; VIM=${1}; shift 1;;
        -*) echo "unknown option ${1}" >&1; exit 1;;
    esac
done

main()
{
    local session_files=("${@}")
    [ ${#session_files[@]} -eq 0 ] && session_files=("${SESSION_FILE_DEFAULT}")

    local vim_files
    vim_files=(
        $(parse_session_files "${session_files[@]}" || return ${?})
    ) || return ${?}

    local cmd
    cmd="TERM=screen-256color ${VIM} -- $(echo "${vim_files[@]}")" || return ${?}
    ${DBG} && echo "${cmd}" >&2 || eval "${cmd}"

    return 0
}

#
# Parse multiple sessions files for file paths.
#
parse_session_files()
{
    local files=("${@}")
    ${DBG} && echo "parse_session_files" >&2
    ${DBG} && echo "| files: ${files[@]}" >&2
    local file
    for file in "${files[@]}"
    do
        parse_session_file "${file}" || return ${?}
    done
    return 0
}

#
# Parse single sessions file (possibly nested) for file paths.
#
parse_session_file()
{
    local file="${1}"
    ${DBG} && echo "parse_session_file" >&2
    ${DBG} && echo "| file: ${file}" >&2
    [ ! -f "${file}" ] && { echo "no such file: '${file}'" >&2; return 1; }
    local root="$(realpath --relative-to="." "$(dirname ${file})")"
    ${DBG} && echo "> root: ${root}" >&2
    ${DBG} && echo "> read lines from ${file}" >&2
    local line
    while read line
    do
        ${DBG} && echo "  '${line}'" >&2
        line="$(echo ${line})"  # strip whitespace
        if [ "${line:0:1}" == '<' ]
        then
            local sub_file="${root}/$(echo ${line:1})"  # strip whitespace
            ${DBG} && echo "  - sub_file: ${sub_file}" >&2
            parse_session_file "${sub_file}" "${root}/$(dirname "${sub_file}")" || return ${?}
        else
            parse_session_line "${line}" "${root}" || return ${?}
        fi
    done < "${file}"
    return 0
}

#
# Parse a line in a sessions file for file paths.
#
parse_session_line()
{
    local line="${1}"
    local root="${2}"
    ${DBG} && echo "parse_session_line" >&2
    ${DBG} && echo "| line: ${line}" >&2
    ${DBG} && echo "| root: ${root}" >&2
    line="$(echo "${line}" | sed -e 's/^ \+//' -e 's/#.*$//')"
    [ "${line}" == '' ] && return 0
    local file="$(echo "${root}/${line}" | sed -e 's@\./@@' -e 's@/./@/@g')"
    echo "${file}"
    return 0
}

main "$@"