#! /usr/bin/perl

# This is a skeleton of a perl script for processing the output of

# sgmls.  You must change the parts marked with "XXX".

# XXX This is for troff: in data, turn \ into \e (which prints as \).

# Backslashes in SDATA entities are left as backslashes.

$backslash_in_data = "\\e";

$prog = $0;

$prog =~ s|.*/||;

$level = 0;

while (<STDIN>) {

    chop;

    $command = substr($_, 0, 1);

    substr($_, 0, 1) = "";

    if ($command eq '(') {

	&start_element($_);

	$level++;

    }

    elsif ($command eq ')') {

	$level--;

	&end_element($_);

	foreach $key (keys %attribute_value) {

	    @splitkey = split($;, $key);

	    if ($splitkey[0] == $level) {

		delete $attribute_value{$key};

		delete $attribute_type{$key};

	    }

	}

    }

    elsif ($command eq '-') {

	&unescape_data($_);

	&data($_);

    }

    elsif ($command eq 'A') {

	@field = split(/ /, $_, 3);

	$attribute_type{$level,$field[0]} = $field[1];

	&unescape_data($field[2]);

	$attribute_value{$level,$field[0]} = $field[2];

    }

    elsif ($command eq '&') {

	&entity($_);

    }

    elsif ($command eq 'D') {

	@field = split(/ /, $_, 4);

	$data_attribute_type{$field[0], $field[1]} = $field[2];

	&unescape_data($field[3]);

	$data_attribute_value{$field[0], $field[1]} = $field[3];

    }

    elsif ($command eq 'N') {

	$notation{$_} = 1;

	if (defined($sysid)) {

	    $notation_sysid{$_} = $sysid;

	    undef($sysid);

	}

	if (defined($pubid)) {

	    $notation_pubid{$_} = $pubid;

	    undef($pubid);

	}

    }

    elsif ($command eq 'I') {

        @field = split(/ /, $_, 3);

	$entity_type{$field[0]} = $field[1];

	&unescape($field[2]);

	# You may want to substitute \e for \ if the type is CDATA.

	$entity_text{$field[0]} = $field[2];

	$entity_code{$field[0]} = 'I';

    }

    elsif ($command eq 'E') {

	@field = split(/ /, $_);

	$entity_code{$field[0]} = 'E';

	$entity_type{$field[0]} = $field[1];

	$entity_notation{$field[0]} = $field[2];

	if (defined(@files)) {

	    foreach $i (0..$#files) {

		$entity_filename{$field[0], $i} = $files[i];

	    }

	    undef(@files);

	}

	if (defined($sysid)) {

	    $entity_sysid{$field[0]} = $sysid;

	    undef($sysid);

	}

	if (defined($pubid)) {

	    $entity_pubid{$field[0]} = $pubid;

	    undef($pubid);

	}

    }

    elsif ($command eq 'S') {

	$entity_code{$_} = 'S';

	if (defined(@files)) {

	    foreach $i (0..$#files) {

		$entity_filename{$_, $i} = $files[i];

	    }

	    undef(@files);

	}

	if (defined($sysid)) {

	    $entity_sysid{$_} = $sysid;

	    undef($sysid);

	}

	if (defined($pubid)) {

	    $entity_pubid{$_} = $pubid;

	    undef($pubid);

	}

    }

    elsif ($command eq '?') {

	&unescape($_);

	&pi($_);

    }

    elsif ($command eq 'L') {

	@field = split(/ /, $_);

	$lineno = $field[0];

	if ($#field >= 1) {

	    &unescape($field[1]);

	    $filename = $field[1];

	}

    }

    elsif ($command eq 'V') {

	@field = split(/ /, $_, 2);

	&unescape($field[1]);

	$environment{$field[0]} = $field[1];

    }

    elsif ($command eq '{') {

	&start_subdoc($_);

    }

    elsif ($command eq '}') {

	&end_subdoc($_);

    }

    elsif ($command eq 'f') {

	&unescape($_);

	push(@files, $_);

    }

    elsif ($command eq 'p') {

	&unescape($_);

	$pubid = $_;

    }

    elsif ($command eq 's') {

	&unescape($_);

	$sysid = $_;

    }

    elsif ($command eq 'C') {

	$conforming = 1;

    }

    else {

	warn "$prog:$ARGV:$.: unrecognized command \`$command'\n";

    }

}

sub unescape {

    $_[0] =~ s/\\([0-7][0-7]?[0-7]?|.)/&esc($1)/eg;

}

sub esc {

    local($_) = $_[0];

    if ($_ eq '012' || $_ eq '12') {

	"";			# ignore RS

    }

    elsif (/^[0-7]/) {

	sprintf("%c", oct);

    }

    elsif ($_ eq 'n') {

	"\n";

    }

    elsif ($_ eq '|') {

	"";

    }

    elsif ($_ eq "\\") {

	"\\";

    }

    else {

	$_;

    }

}

sub unescape_data {

    local($sdata) = 0;

    $_[0] =~ s/\\([0-7][0-7]?[0-7]?|.)/&esc_data($1)/eg;

}

sub esc_data {

    local($_) = $_[0];

    if ($_ eq '012' || $_ eq '12') {

	"";			# ignore RS

    }

    elsif (/^[0-7]/) {

	sprintf("%c", oct);

    }

    elsif ($_ eq 'n') {

	"\n";

    }

    elsif ($_ eq '|') {

	$sdata = !$sdata;

	"";

    }

    elsif ($_ eq "\\") {

	$sdata ? "\\" : $backslash_in_data;

    }

    else {

	$_;

    }

}

sub start_element {

    local($gi) = $_[0];

    # XXX

}

sub end_element {

    local($gi) = $_[0];

    # XXX

}

sub data {

    local($data) = $_[0];

    # XXX

}

# A processing instruction.

sub pi {

    local($data) = $_[0];

    # XXX

}

# A reference to an external entity.

sub entity {

    local($name) = $_[0];

    # XXX

}

sub start_subdoc {

    local($name) = $_[0];

    # XXX

}

sub end_subdoc {

    local($name) = $_[0];

    # XXX

}