foounparser.pm

用于词法分析的词法分析器

# $Id: FooUnparser.pm,v 1.3 1996/07/27 07:47:22 matt Exp $
#
# Foo unparser utility
#
# (c) June 96 Matt Phillips.

require 'FooObject.pm';

package FooUnparser;

# unparses object to file.
sub unparse
{
  my ($file, $object) = @_;

  doObject ($file, $object, 0);
}

sub doObject
{
  my ($file, $object, $indent) = @_;

  if ($object->isAtomic ())
  {
    my $value = $object->getAttr ();

    # change control/binary chars into \ddd form
    $value =~ s/([\x00-\x20\x80-\xff])/sprintf ("\\%02x", ord ($1))/ge;
    # escape any "'s
    $value =~ s/\"/\\\"/g;

    print $file ("\"$value\"");
  } else
  {
    my $first = 1;		# true if at first attribute

    print $file ('( ');

    # output each attribute
    for $attr ($object->getAttrNames ())
    {
      newlineAndIndent ($file, $indent + 1) if !$first;
      $first = 0;
      doAttr ($file, $attr, $object->getAttrs ($attr), $indent + 1);
    }

    newlineAndIndent ($file, $indent);
    print $file (')')
  }
}

sub doAttr
{
  my ($file, $attr, $values, $indent) = @_;

  print $file ($attr);

  if ($#$values == 0)
  {				# no []'s if single value for attr
    my $value = $$values[0];

    if ($value->isAtomic ())
    {				# put value on same line if atomic
      print $file ("\t");
    } else
    {
      newlineAndIndent ($file, $indent);
    }
    doObject ($file, $value, $indent);
  } else
  {				# use [] form for values
    my $first = 1;

    newlineAndIndent ($file, $indent);
    print $file ('[ ');

    for $value (@$values)
    {
      newlineAndIndent ($file, $indent + 1) if !$first;
      $first = 0;
      doObject ($file, $value, $indent + 1);
    }

    newlineAndIndent ($file, $indent);
    print $file (']');
  }
}

sub newlineAndIndent
{
  my ($file, $indent) = @_;

  print $file ("\n", '  'x$indent);
}