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[p5sagit/p5-mst-13.2.git] / lib / assertions.pm

diff --git a/lib/assertions.pm b/lib/assertions.pm
index 50e06a7..700abf4 100644 (file)
--- a/lib/assertions.pm
+++ b/lib/assertions.pm
@@ -6,23 +6,116 @@ our $VERSION = '0.01';
 # 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 @_;
-
-    if ($_[0] eq '&') {
-       return unless $^H & $hint;
-       shift;
-    }
-       
-    for my $tag (@_) {
-       unless (grep { $tag=~$_ } @{^ASSERTING}) {
+    foreach my $expr (@_) {
+       unless (calc_expr $expr) {
+           # print STDERR "assertions deactived";
            $^H &= ~$hint;
+           $^H |= $seen_hint;
            return;
        }
     }
-    $^H |= $hint;
+    # print STDERR "assertions actived";
+    $^H |= $hint|$seen_hint;
 }
 
 sub unimport {
@@ -35,7 +128,7 @@ __END__
 
 =head1 NAME
 
-assertions - selects assertions
+assertions - select assertions in blocks of code
 
 =head1 SYNOPSIS
 
@@ -46,49 +139,50 @@ assertions - selects assertions
 
   {
       use assertions qw( foo bar );
-      assert { print "asserting 'foo' & 'bar'\n" };
+      assert { print "asserting 'foo' and 'bar'\n" };
   }
 
   {
       use assertions qw( bar );
-      assert { print "asserting 'bar'\n" };
+      assert { print "asserting only 'bar'\n" };
   }
 
   {
-      use assertions qw( & bar );
-      assert { print "asserting 'foo' & '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
 
+The C<assertions> pragma specifies the tags used to enable and disable
+the execution of assertion subroutines.
 
+An assertion subroutine is declared with the C<:assertion> attribute.
+This subroutine is not normally executed : it's optimized away by perl
+at compile-time.
 
-
-=head2 EXPORT
-
-None by default.
+The C<assertion> pragma associates to its lexical scope one or several
+assertion tags. Then, to activate the execution of the assertions
+subroutines in this scope, these tags must be given to perl via the
+B<-A> command-line option.
 
 =head1 SEE ALSO
 
-
+L<perlrun>.
 
 =head1 AUTHOR
 
-Salvador Fandiño, E<lt>sfandino@yahoo.comE<gt>
+Salvador FandiE<ntilde>o, E<lt>sfandino@yahoo.comE<gt>
 
 =head1 COPYRIGHT AND LICENSE
 
-Copyright 2002 by Salvador Fandiño
+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
+
+TODO : Some more docs are to be added about assertion expressions.