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1 | package O; |
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2 | |
3 | our $VERSION = '1.00'; |
4 | |
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5 | use B qw(minus_c save_BEGINs); |
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6 | use Carp; |
7 | |
8 | sub import { |
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9 | my ($class, @options) = @_; |
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10 | my ($quiet, $veryquiet) = (0, 0); |
11 | if ($options[0] eq '-q' || $options[0] eq '-qq') { |
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12 | $quiet = 1; |
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13 | open (SAVEOUT, ">&STDOUT"); |
14 | close STDOUT; |
15 | open (STDOUT, ">", \$O::BEGIN_output); |
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16 | if ($options[0] eq '-qq') { |
17 | $veryquiet = 1; |
18 | } |
19 | shift @options; |
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20 | } |
21 | my $backend = shift (@options); |
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22 | eval q[ |
23 | BEGIN { |
24 | minus_c; |
25 | save_BEGINs; |
26 | } |
27 | |
28 | CHECK { |
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29 | if ($quiet) { |
30 | close STDOUT; |
31 | open (STDOUT, ">&SAVEOUT"); |
32 | close SAVEOUT; |
33 | } |
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34 | use B::].$backend.q[ (); |
35 | if ($@) { |
36 | croak "use of backend $backend failed: $@"; |
37 | } |
38 | |
39 | |
40 | my $compilesub = &{"B::${backend}::compile"}(@options); |
41 | if (ref($compilesub) ne "CODE") { |
42 | die $compilesub; |
43 | } |
44 | |
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45 | local ($\,$",$,) = (undef,' ',''); |
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46 | &$compilesub(); |
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47 | |
48 | close STDERR if $veryquiet; |
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49 | } |
50 | ]; |
51 | die $@ if $@; |
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52 | } |
53 | |
54 | 1; |
55 | |
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56 | __END__ |
57 | |
58 | =head1 NAME |
59 | |
60 | O - Generic interface to Perl Compiler backends |
61 | |
62 | =head1 SYNOPSIS |
63 | |
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64 | perl -MO=[-q,]Backend[,OPTIONS] foo.pl |
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65 | |
66 | =head1 DESCRIPTION |
67 | |
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68 | This is the module that is used as a frontend to the Perl Compiler. |
69 | |
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70 | If you pass the C<-q> option to the module, then the STDOUT |
71 | filehandle will be redirected into the variable C<$O::BEGIN_output> |
72 | during compilation. This has the effect that any output printed |
73 | to STDOUT by BEGIN blocks or use'd modules will be stored in this |
74 | variable rather than printed. It's useful with those backends which |
75 | produce output themselves (C<Deparse>, C<Concise> etc), so that |
76 | their output is not confused with that generated by the code |
77 | being compiled. |
78 | |
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79 | The C<-qq> option behaves like C<-q>, except that it also closes |
80 | STDERR after deparsing has finished. This suppresses the "Syntax OK" |
81 | message normally produced by perl. |
82 | |
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83 | =head1 CONVENTIONS |
84 | |
85 | Most compiler backends use the following conventions: OPTIONS |
86 | consists of a comma-separated list of words (no white-space). |
87 | The C<-v> option usually puts the backend into verbose mode. |
88 | The C<-ofile> option generates output to B<file> instead of |
89 | stdout. The C<-D> option followed by various letters turns on |
90 | various internal debugging flags. See the documentation for the |
91 | desired backend (named C<B::Backend> for the example above) to |
92 | find out about that backend. |
93 | |
94 | =head1 IMPLEMENTATION |
95 | |
96 | This section is only necessary for those who want to write a |
97 | compiler backend module that can be used via this module. |
98 | |
99 | The command-line mentioned in the SYNOPSIS section corresponds to |
100 | the Perl code |
101 | |
102 | use O ("Backend", OPTIONS); |
103 | |
104 | The C<import> function which that calls loads in the appropriate |
105 | C<B::Backend> module and calls the C<compile> function in that |
106 | package, passing it OPTIONS. That function is expected to return |
107 | a sub reference which we'll call CALLBACK. Next, the "compile-only" |
108 | flag is switched on (equivalent to the command-line option C<-c>) |
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109 | and a CHECK block is registered which calls CALLBACK. Thus the main |
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110 | Perl program mentioned on the command-line is read in, parsed and |
111 | compiled into internal syntax tree form. Since the C<-c> flag is |
112 | set, the program does not start running (excepting BEGIN blocks of |
113 | course) but the CALLBACK function registered by the compiler |
114 | backend is called. |
115 | |
116 | In summary, a compiler backend module should be called "B::Foo" |
117 | for some foo and live in the appropriate directory for that name. |
118 | It should define a function called C<compile>. When the user types |
119 | |
120 | perl -MO=Foo,OPTIONS foo.pl |
121 | |
122 | that function is called and is passed those OPTIONS (split on |
123 | commas). It should return a sub ref to the main compilation function. |
124 | After the user's program is loaded and parsed, that returned sub ref |
125 | is invoked which can then go ahead and do the compilation, usually by |
126 | making use of the C<B> module's functionality. |
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127 | |
128 | =head1 AUTHOR |
129 | |
130 | Malcolm Beattie, C<mbeattie@sable.ox.ac.uk> |
131 | |
132 | =cut |