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Devel::CheckLib is a perl module that checks whether a particular C
library and its headers are available.

=head1 SYNOPSIS

    use Devel::CheckLib;

    check_lib_or_exit( lib => 'jpeg', header => 'jpeglib.h' );
    check_lib_or_exit( lib => [ 'iconv', 'jpeg' ] );
  
    # or prompt for path to library and then do this:
    check_lib_or_exit( lib => 'jpeg', libpath => $additional_path );

=head1 USING IT IN Makefile.PL or Build.PL

If you want to use this from Makefile.PL or Build.PL, do
not simply copy the module into your distribution as this may cause
problems when PAUSE and search.cpan.org index the distro.  Instead, use
the use-devel-checklib script.

=head1 HOW IT WORKS

You pass named parameters to a function, describing to it how to build
and link to the libraries.

It works by trying to compile some code - which defaults to this:

    int main(int argc, char *argv[]) { return 0; }

and linking it to the specified libraries.  If something pops out the end
which looks executable, it gets executed, and if main() returns 0 we know
that it worked.  That tiny program is
built once for each library that you specify, and (without linking) once
for each header file.

If you want to check for the presence of particular functions in a
library, or even that those functions return particular results, then
you can pass your own function body for main() thus:

    check_lib_or_exit(
        function => 'foo();if(libversion() > 5) return 0; else return 1;'
        incpath  => ...
        libpath  => ...
        lib      => ...
        header   => ...
    );

In that case, it will fail to build if either foo() or libversion() don't
exist, and main() will return the wrong value if libversion()'s return
value isn't what you want.

=head1 FUNCTIONS

All of these take the same named parameters and are exported by default.
To avoid exporting them, C<use Devel::CheckLib ()>.

=head2 assert_lib

This takes several named parameters, all of which are optional, and dies
with an error message if any of the libraries listed can
not be found.  B<Note>: dying in a Makefile.PL or Build.PL may provoke
a 'FAIL' report from CPAN Testers' automated smoke testers.  Use 
C<check_lib_or_exit> instead.

The named parameters are:

=over

=item lib

Must be either a string with the name of a single 
library or a reference to an array of strings of library names.  Depending
on the compiler found, library names will be fed to the compiler either as
C<-l> arguments or as C<.lib> file names.  (E.g. C<-ljpeg> or C<jpeg.lib>)

=item libpath

a string or an array of strings
representing additional paths to search for libraries.

=item LIBS

a C<ExtUtils::MakeMaker>-style space-separated list of
libraries (each preceded by '-l') and directories (preceded by '-L').

This can also be supplied on the command-line.

=item debug

If true - emit information during processing that can be used for
debugging.

=back

And libraries are no use without header files, so ...

=over

=item header

Must be either a string with the name of a single 
header file or a reference to an array of strings of header file names.

=item incpath

a string or an array of strings
representing additional paths to search for headers.

=item INC

a C<ExtUtils::MakeMaker>-style space-separated list of
incpaths, each preceded by '-I'.

This can also be supplied on the command-line.

=item ccflags

Extra flags to pass to the compiler.

=item ldflags

Extra flags to pass to the linker.

=item analyze_binary

a callback function that will be invoked in order to perform custom
analysis of the generated binary. The callback arguments are the
library name and the path to the binary just compiled.

It is possible to use this callback, for instance, to inspect the
binary for further dependencies.

=back

=head2 check_lib_or_exit

This behaves exactly the same as C<assert_lib()> except that instead of
dieing, it warns (with exactly the same error message) and exits.
This is intended for use in Makefile.PL / Build.PL
when you might want to prompt the user for various paths and
things before checking that what they've told you is sane.

If any library or header is missing, it exits with an exit value of 0 to avoid
causing a CPAN Testers 'FAIL' report.  CPAN Testers should ignore this
result -- which is what you want if an external library dependency is not
available.

=head2 check_lib

This behaves exactly the same as C<assert_lib()> except that it is silent,
returning false instead of dieing, or true otherwise.

=cut

sub check_lib_or_exit {
    eval 'assert_lib(@_)';
    if($@) {
        warn $@;
        exit;
    }
}

sub check_lib {
    eval 'assert_lib(@_)';
    return $@ ? 0 : 1;
}

# borrowed from Text::ParseWords
sub _parse_line {
    my($delimiter, $keep, $line) = @_;
    my($word, @pieces);

    no warnings 'uninitialized';  # we will be testing undef strings

    while (length($line)) {
        # This pattern is optimised to be stack conservative on older perls.
        # Do not refactor without being careful and testing it on very long strings.
        # See Perl bug #42980 for an example of a stack busting input.
        $line =~ s/^
                    (?:
                        # double quoted string
                        (")                             # $quote
                        ((?>[^\\"]*(?:\\.[^\\"]*)*))"   # $quoted
        | # --OR--
                        # singe quoted string
                        (')                             # $quote
                        ((?>[^\\']*(?:\\.[^\\']*)*))'   # $quoted
                    |   # --OR--
                        # unquoted string
                        (                               # $unquoted
                            (?:\\.|[^\\"'])*?
                        )
                        # followed by
                        (                               # $delim
                            \Z(?!\n)                    # EOL
                        |   # --OR--
                            (?-x:$delimiter)            # delimiter
                        |   # --OR--