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Diffstat (limited to 'Master/tlpkg/tlperl/lib/O.pm')
| -rwxr-xr-x | Master/tlpkg/tlperl/lib/O.pm | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/Master/tlpkg/tlperl/lib/O.pm b/Master/tlpkg/tlperl/lib/O.pm new file mode 100755 index 00000000000..2976a894208 --- /dev/null +++ b/Master/tlpkg/tlperl/lib/O.pm @@ -0,0 +1,143 @@ +package O; + +our $VERSION = '1.01'; + +use B qw(minus_c save_BEGINs); +use Carp; + +sub import { + my ($class, @options) = @_; + my ($quiet, $veryquiet) = (0, 0); + if ($options[0] eq '-q' || $options[0] eq '-qq') { + $quiet = 1; + open (SAVEOUT, ">&STDOUT"); + close STDOUT; + open (STDOUT, ">", \$O::BEGIN_output); + if ($options[0] eq '-qq') { + $veryquiet = 1; + } + shift @options; + } + my $backend = shift (@options); + eval q[ + BEGIN { + minus_c; + save_BEGINs; + } + + CHECK { + if ($quiet) { + close STDOUT; + open (STDOUT, ">&SAVEOUT"); + close SAVEOUT; + } + + # Note: if you change the code after this 'use', please + # change the fudge factors in B::Concise (grep for + # "fragile kludge") so that its output still looks + # nice. Thanks. --smcc + use B::].$backend.q[ (); + if ($@) { + croak "use of backend $backend failed: $@"; + } + + + my $compilesub = &{"B::${backend}::compile"}(@options); + if (ref($compilesub) ne "CODE") { + die $compilesub; + } + + local $savebackslash = $\; + local ($\,$",$,) = (undef,' ',''); + &$compilesub(); + + close STDERR if $veryquiet; + } + ]; + die $@ if $@; +} + +1; + +__END__ + +=head1 NAME + +O - Generic interface to Perl Compiler backends + +=head1 SYNOPSIS + + perl -MO=[-q,]Backend[,OPTIONS] foo.pl + +=head1 DESCRIPTION + +This is the module that is used as a frontend to the Perl Compiler. + +If you pass the C<-q> option to the module, then the STDOUT +filehandle will be redirected into the variable C<$O::BEGIN_output> +during compilation. This has the effect that any output printed +to STDOUT by BEGIN blocks or use'd modules will be stored in this +variable rather than printed. It's useful with those backends which +produce output themselves (C<Deparse>, C<Concise> etc), so that +their output is not confused with that generated by the code +being compiled. + +The C<-qq> option behaves like C<-q>, except that it also closes +STDERR after deparsing has finished. This suppresses the "Syntax OK" +message normally produced by perl. + +=head1 CONVENTIONS + +Most compiler backends use the following conventions: OPTIONS +consists of a comma-separated list of words (no white-space). +The C<-v> option usually puts the backend into verbose mode. +The C<-ofile> option generates output to B<file> instead of +stdout. The C<-D> option followed by various letters turns on +various internal debugging flags. See the documentation for the +desired backend (named C<B::Backend> for the example above) to +find out about that backend. + +=head1 IMPLEMENTATION + +This section is only necessary for those who want to write a +compiler backend module that can be used via this module. + +The command-line mentioned in the SYNOPSIS section corresponds to +the Perl code + + use O ("Backend", OPTIONS); + +The C<O::import> function loads the appropriate C<B::Backend> module +and calls its C<compile> function, passing it OPTIONS. That function +is expected to return a sub reference which we'll call CALLBACK. Next, +the "compile-only" flag is switched on (equivalent to the command-line +option C<-c>) and a CHECK block is registered which calls +CALLBACK. Thus the main Perl program mentioned on the command-line is +read in, parsed and compiled into internal syntax tree form. Since the +C<-c> flag is set, the program does not start running (excepting BEGIN +blocks of course) but the CALLBACK function registered by the compiler +backend is called. + +In summary, a compiler backend module should be called "B::Foo" +for some foo and live in the appropriate directory for that name. +It should define a function called C<compile>. When the user types + + perl -MO=Foo,OPTIONS foo.pl + +that function is called and is passed those OPTIONS (split on +commas). It should return a sub ref to the main compilation function. +After the user's program is loaded and parsed, that returned sub ref +is invoked which can then go ahead and do the compilation, usually by +making use of the C<B> module's functionality. + +=head1 BUGS + +The C<-q> and C<-qq> options don't work correctly if perl isn't +compiled with PerlIO support : STDOUT will be closed instead of being +redirected to C<$O::BEGIN_output>. + +=head1 AUTHOR + +Malcolm Beattie, C<mbeattie@sable.ox.ac.uk> + +=cut |