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|
package assertions;
our $VERSION = '0.01';
# use strict;
# use warnings;
my $hint=0x01000000;
my $seen_hint=0x02000000;
sub syntax_error ($$) {
my ($expr, $why)=@_;
require Carp;
Carp::croak("syntax error on assertion filter '$expr' ($why)");
}
sub my_warn ($) {
my $error=shift;
require warnings;
if (warnings::enabled('assertions')) {
require Carp;
Carp::carp($error);
}
}
sub calc_expr {
my $expr=shift;
my @tokens=split / \s*
( && # and
| \|\| # or
| \( # parents
| \) )
\s*
| \s+ # spaces out
/x, $expr;
# print STDERR "tokens: -", join('-',@tokens), "-\n";
my @now=1;
my @op='start';
for my $t (@tokens) {
next if (!defined $t or $t eq '');
if ($t eq '(') {
unshift @now, 1;
unshift @op, 'start';
}
else {
if ($t eq '||') {
defined $op[0]
and syntax_error $expr, 'consecutive operators';
$op[0]='||';
}
elsif ($t eq '&&') {
defined $op[0]
and syntax_error $expr, 'consecutive operators';
$op[0]='&&';
}
else {
if ($t eq ')') {
@now==1 and
syntax_error $expr, 'unbalanced parens';
defined $op[0] and
syntax_error $expr, "key missing after operator '$op[0]'";
$t=shift @now;
shift @op;
}
elsif ($t eq '_') {
unless ($^H & $seen_hint) {
my_warn "assertion status '_' referenced but not previously defined";
}
$t=($^H & $hint) ? 1 : 0;
}
elsif ($t ne '0' and $t ne '1') {
# print STDERR "'$t' resolved as ";
$t=grep ({ $t=~$_ } @{^ASSERTING}) ? 1 : 0;
# print STDERR "$t\n";
}
defined $op[0] or
syntax_error $expr, 'operator expected';
if ($op[0] eq 'start') {
$now[0]=$t;
}
elsif ($op[0] eq '||') {
$now[0]||=$t;
}
else {
$now[0]&&=$t;
}
undef $op[0];
}
}
}
@now==1 or syntax_error $expr, 'unbalanced parens';
defined $op[0] and syntax_error $expr, "expression ends on operator '$op[0]'";
return $now[0];
}
sub import {
# print STDERR "\@_=", join("|", @_), "\n";
shift;
@_=(scalar(caller)) unless @_;
foreach my $expr (@_) {
unless (calc_expr $expr) {
# print STDERR "assertions deactived";
$^H &= ~$hint;
$^H |= $seen_hint;
return;
}
}
# print STDERR "assertions actived";
$^H |= $hint|$seen_hint;
}
sub unimport {
$^H &= ~$hint;
}
1;
__END__
=head1 NAME
assertions - selects assertions
=head1 SYNOPSIS
sub assert (&) : assertion { &{$_[0]}() }
use assertions 'foo';
assert { print "asserting 'foo'\n" };
{
use assertions qw( foo bar );
assert { print "asserting 'foo' & 'bar'\n" };
}
{
use assertions qw( bar );
assert { print "asserting 'bar'\n" };
}
{
use assertions ' _ && bar ';
assert { print "asserting 'foo' && 'bar'\n" };
}
assert { print "asserting 'foo' again\n" };
=head1 ABSTRACT
C<assertions> pragma selects the tags used to control assertion
execution.
=head1 DESCRIPTION
=head2 EXPORT
None by default.
=head1 SEE ALSO
=head1 AUTHOR
Salvador FandiE<ntilde>o, E<lt>sfandino@yahoo.comE<gt>
=head1 COPYRIGHT AND LICENSE
Copyright 2002 by Salvador FandiE<ntilde>o
This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.
=cut
|
