annotate vext @ 1707:a4da817dc221 vext

Use vext only if we are in a Mercurial checkout

#!/bin/bash

# Disable shellcheck warnings for useless-use-of-cat. UUOC is good
# practice, not bad: clearer, safer, less error-prone.
# shellcheck disable=SC2002

sml="$VEXT_SML"

set -eu

mydir=$(dirname "$0")
program="$mydir/vext.sml"

# We need one of Poly/ML, SML/NJ, or MLton. Since we're running a
# single-file SML program as if it were a script, our order of
# preference is based on startup speed.

if [ -z "$sml" ]; then
    # I think there may be a race condition in the poly interpreter's
    # tests for open or closed I/O streams - without the "echo" here,
    # or with stderr redirection, this pipeline will sometimes hang
    if echo | poly -v 2>/dev/null | grep -q 'Poly/ML'; then
	sml="poly"
    elif sml -h 2>&1 | grep -q 'Standard ML of New Jersey'; then
	sml="smlnj"
    elif mlton 2>&1 | grep -q 'MLton'; then
	sml="mlton"
    else cat 1>&2 <<EOF

ERROR: No supported SML compiler or interpreter found       
EOF
	cat <<EOF

  The Vext external source code manager needs a Standard ML (SML)
  compiler or interpreter to run.

  Please ensure you have one of the following SML implementations
  installed and present in your PATH, and try again. These are listed
  approximately in order of preference for this task.

    1. Poly/ML
       - often found in a distribution package called: polyml
       - executable name: poly

    2. Standard ML of New Jersey
       - often found in a distribution package called: smlnj
       - executable name: sml

    3. MLton
       - often found in a distribution package called: mlton
       - executable name: mlton

EOF
	exit 2
    fi
fi

tmp_sml=$(mktemp /tmp/vext-XXXXXXXX.sml)
tmp_out=$(mktemp /tmp/vext-XXXXXXXX.bin)

trap 'rm -f $tmp_sml $tmp_out' 0

arglist=""
for arg in "$@"; do
    if [ -n "$arglist" ]; then arglist="$arglist,"; fi
    if echo "$arg" | grep -q '[^a-z]' ; then
	arglist="$arglist\"usage\""
    else
	arglist="$arglist\"$arg\""
    fi
done

case "$sml" in
    poly) echo 'use "'"$program"'"; vext ['"$arglist"'];' |
		poly -q --error-exit ;;
    mlton)
	cat "$program" > "$tmp_sml"
	echo 'val _ = main ()' >> "$tmp_sml"
	mlton -output "$tmp_out" "$tmp_sml"
	"$tmp_out" "$@" ;;
    smlnj)
	cat "$program" | (
	    cat <<EOF
val smlrun__cp = 
    let val x = !Control.Print.out in
        Control.Print.out := { say = fn _ => (), flush = fn () => () };
        x
    end;
val smlrun__prev = ref "";
Control.Print.out := { 
    say = fn s => 
        (if String.isSubstring " Error" s
         then (Control.Print.out := smlrun__cp;
               (#say smlrun__cp) (!smlrun__prev);
               (#say smlrun__cp) s)
         else (smlrun__prev := s; ())),
    flush = fn s => ()
};
EOF
	    cat -
	    cat <<EOF
val _ = vext [$arglist];
val _ = OS.Process.exit (OS.Process.success);
EOF
            ) > "$tmp_sml"
	CM_VERBOSE=false sml "$tmp_sml" ;;
    *)
	echo "Unknown SML implementation name: $sml";
	exit 2 ;;
esac