set -o errexit # in case caller did not have -e in #! line

function extern () { (exec "$@") || return; }

isset () { test -n "${!1+isset}"; }

realpath () { readlink -f -- "$1"; }

include_guard_var () { realpath "$1"|"extern" sed 's/[^a-zA-Z0-9_]/_/g'; }

self_not_included () # usage: if self_not_included; then ... fi

	test $# -ge 1 || set -- "${BASH_SOURCE[1]}"

	local include_guard="$(include_guard_var "$1")"

	alias self_being_included=false

	! isset "$include_guard" && \

	{ eval "$include_guard"=1; alias self_being_included=true; }

}

# to load newly-defined aliases for use in functions in the same file:

if self_not_included "${BASH_SOURCE[0]}"; then

shopt -s expand_aliases

unalias () { builtin unalias "$@" 2>&- || true; } # no error if undefined

#### exceptions

alias rethrow='return "$e"'

fi # load new aliases

function log_e () # usage: log_e cmd... [ || use $e (or $?) ]

	if ! "save_e" "$@"; then

		echo "! $*" >&2

alias log_e='declare e; log_e ' # last space alias-expands next word

# usage: try cmd...; ignore status; if catch status; then ...; fi; end_try

function try () { "save_e" "$@" || true; }

alias end_try='rethrow'

#### integers

bool2int () { save_e test -z "$1"; echo "$e"; } # empty->0; non-empty->1

#### arrays

join () { local IFS="$delim"; echo "$*"; } # usage: delim=... join elems...

reverse () # usage: array=($(reverse args...))

#### verbose output

# usage: (stdout2stderr; cmd...) || return

stdout2stderr () { exec >&2; }

# set verbosity

if isset verbose; then : "${verbosity:=$(bool2int "$verbose")}"; fi

: "${verbosity=3}" # default

declare -i verbosity # ensure integer

export verbosity # propagate the verbosity to invoked commands

can_log () { test "$verbosity" -gt 0; } # verbosity=0 turns off all logging

: "${log_indent=  }"

# usage: in func:      inc_log_level; ...

alias inc_log_level='declare verbosity="$verbosity" PS4="$log_indent$PS4"

fi # load new aliases

# usage: (limit_stderr; cmd...) || return

# `|| return` needed on Mac because of bug where -e doesn't apply to ()

limit_stderr () { inc_log_level; if ! can_log; then exec 2>/dev/null; fi; }

limit_stderr_cmd () # usage: [stdout2stderr=1] limit_stderr_cmd cmd...

{

	case "$1" in echo_run) shift; echo_cmd "$@";; esac

	(limit_stderr

		if test -n "$stdout2stderr"; then stdout2stderr; fi

	) || return

}

alias limit_stderr_cmd='limit_stderr_cmd ' # last space alias-expands next word

echo_cmd () { if can_log; then echo "$PS4$*" >&2; fi; }

echo_run () { echo_cmd "$@"; "$@"; }

# auto-echo common external commands

# echo all external commands

alias self='extern "$FUNCNAME"' # usage: wrapper () { self ...; }

# commands that are always external

canon_rel_path ()

	path="$(realpath "$path")" # canonicalize

	path="${path#$(pwd -P)/}" # remove any shared prefix with the current dir

	echo "$path"

fi # load new aliases

if self_being_included; then

function echo_func ()

{

	inc_log_level

	local script="$(canon_rel_path "${BASH_SOURCE[1]}")"

}

# usage: cmd1 | { pipe_delay; cmd2; }

echo_stdin () # usage: input|echo_stdin|cmd

	inc_log_level

	if can_log; then

		pipe_delay

		echo ----- >&2

}

echo_vars () # usage: echo_vars var...

{

	inc_log_level; inc_log_level

	if can_log; then

}

	builtin export "$@"

	echo_vars "$@"

if test "$verbosity" -ge 2; then

	alias export="echo_export" # automatically echo env vars when they are set

usage () { echo "Usage: $1" >&2; (exit 2); }

fi # load new aliases

#### strings

sed () { self -"$sed_ere_flag" "$@";}

#### vars

set_inv () { set_var no_"$1" "$(test -n "${!1}" || echo 1)"; }

# usage: local var=...; local_inv

alias local_inv='declare "no_$var=$(test -n "${!var}" || echo 1)"'

# usage: local prefix=..._; import_vars

#### commands

top_script="$0" # outermost script

# auto-removes a command's output file on error (like make's .DELETE_ON_ERROR)

run_args_cmd () # runs the command line args command

{

	test $? -eq 0 || return

	eval set -- "$(reverse "${BASH_ARGV[@]}")"

	test $# -ge 1 || set -- all

	echo_cmd "$(canon_rel_path "$0")" "$@"; "$@"

}

fwd () # usage: subdirs=(...); fwd "$FUNCNAME" "$@"

{

	echo_func

	: "${subdirs?}"

	for subdir in "${subdirs[@]}"; do

		"$(dirname "${BASH_SOURCE[1]}")"/"$subdir"/run "$@"

	done

#### URLs

fi