Runs qgraf in a one-liner. #bin #sh #qgraf

qgraf.sh

#! /bin/sh
#
# @qgraf.sh
#
# Runs qgraf in a one-liner. The output file goes to the standard output, while
# the qgraf output goes to the standard error.
#
set -eu

# The program name.
prog=`basename "$0"`

# Wraps "mktemp -d $1XXXXXXXXXX"
mktemp_d() {(
  umask 077
  {
    # Use mktemp if available.
    dir=`mktemp -d "$1XXXXXXXXXX" 2>/dev/null` && [ -d "$dir" ]
  } || {
    # Fall back on mkdir.
    dir=
    i=0
    while [ $i -lt 100 ]; do
      next_dir=$1$$$i$RANDOM$RANDOM
      if mkdir "$next_dir" >/dev/null 2>&1; then
        dir=$next_dir
        break
      fi
      i=`expr $i + 1`
    done
    [ "x$dir" != x ] && [ -d "$dir" ]
  } || {
    echo "$prog: failed to create a temporary directory" >&2
    exit 1
  }
  echo "$dir"
  exit 0
)}

# Prints the absolute path.
abs_path() {(
  if [ ! -f "$1" ]; then
    echo "$prog: \"$1\" not found" >&2
    exit 1
  fi
  rel_dir=`dirname "$1"`
  abs_dir=`cd "$rel_dir"; pwd`
  fname=`basename "$1"`
  echo "$abs_dir/$fname"
)}

# Prints the usage.
print_usage() {
  cat << END
Usage:
  $prog style=<style-file> model=<model-file>
           in=<in-particles..> out=<out-particles..> loops=<number-of_loops>
           [loop_momentum=<prefix>] [options=<options..>] [<logicals..>]

Options include:
  onepi, onshell, nosigma, nosnail, notadpole, simple,
  onepr, offshell, sigma, snail, tadpole, notsimple,
  floop, topol

  <logical>=<operator>[<arg1>,...,<arg_k>]
  where <logical> is true or false and <operator> is one of
  bridge, chord, iprop, rbridge, sbridge, vsum, psum

Example:
  $ $prog style=form.sty model=qcd in=qua out=qua,glu loops=5 \\
    options=notadpole,onshell,nosnail
END
}

# Determine the path to qgraf.
if [ -z "${QGRAF:-}" ]; then
  if [ -f ./qgraf ]; then
    # Priority goes to qgraf in the current directory.
    QGRAF=./qgraf
  else
    # Hopefully in $PATH.
    QGRAF=`command -v qgraf || :`
  fi
fi
# Convert it into the absolute path when it looks like a relative path.
case "$QGRAF" in
  */*)
    if [ ! -f "$QGRAF" ]; then
      echo "$prog: \"$QGRAF\" not found" >&2
      exit 1
    fi
    QGRAF=`abs_path "$QGRAF"`
    ;;
esac

# Parse the command line arguments.
opt_style=
opt_model=
opt_in=
opt_out=
opt_loops=
opt_loop_momentum=
opt_options=
opt_logicals=

for opt_arg in "$@"; do
  case $opt_arg in
    style=*|model=*|in=*|out=*|loops=*|loop_momentum=*|options=*)
      opt_var=`expr "$opt_arg" : '\([^=]*\)=.*' | sed 's/-/_/g'`
      opt_val=`{ expr "$opt_arg" : '[^=]*=\(.*\)' || :; }`
      eval "opt_$opt_var=\"\$opt_val\""
      ;;
    true=*|false=*)
      opt_logicals="$opt_logicals$opt_arg;
"
      ;;
    *)
      echo "$prog: unrecognized option: $opt_arg" >&2
      print_usage >&2
      exit 1
      ;;
  esac
done

# Check the arguments.
for a in style model in out loops; do
  if [ -z `eval echo "\\$opt_$a"` ]; then
    echo "$prog: forgotten \"$a\". It must have a value" >&2
    print_usage >&2
    exit 1
  fi
done

opt_style=`abs_path "$opt_style"`
opt_model=`abs_path "$opt_model"`

# Make a temporary directory.
tmpdir=`mktemp_d "${TMPDIR:-/tmp}/qgraf"`
trap 'rm -rf "$tmpdir"' 0 1 2 13 15

# Make links to the style and model files.
ln -s "$opt_style" "$tmpdir"
ln -s "$opt_model" "$tmpdir"

# Move to the temporary directory.
(
  cd "$tmpdir"

  # Write qgraf.dat.

  cat << END >qgraf.dat
 output = 'qgraf.out';
 style  = '`basename "$opt_style"`';
 model  = '`basename "$opt_model"`';
 in     = $opt_in;
 out    = $opt_out;
 loops  = $opt_loops;
 loop_momentum  = $opt_loop_momentum;
 options = $opt_options;
 $opt_logicals
END

  # Run qgraf.
  $QGRAF >&2

  # qgraf always returns with an exit code of 0. Check if the output file was
  # actually written.
  if [ ! -f qgraf.out ]; then
    echo "$prog: qgraf failed" >&2
    exit 1
  fi

  # Print the output file.
  cat qgraf.out
)