NAME

       PDL::VectorValued::Dev - development utilities for vector-valued PDLs

SYNOPSIS

        use PDL;
        use PDL::VectorValued::Dev;

        ##---------------------------------------------------------------------
        ## ... stuff happens

DESCRIPTION

       PDL::VectorValued::Dev provides some developer utilities for vector-valued PDLs.  It
       produces code for processing with PDL::PP.

PDL::PP Utilities

   vvpp_def($funcName,%args)
       Wrapper for pp_def() which calls vvpp_expand() on 'Code' and 'BadCode' values in %args.

   $pp_code = vvpp_expand($vvpp_code)
       Expand PDL::VectorValued macros in $vvpp_code.  Currently known PDL::VectorValued macros
       include:

         MACRO_NAME            EXPANSION_SUBROUTINE
         ----------------------------------------------------------------------
         $CMPVEC(...)          vvpp_expand_cmpvec(...)
         $CMPVAL(...)          vvpp_expand_cmpval(...)
         $LB(...)              vvpp_expand_lb(...)

       See the documentation of the individual expansion subroutines for details on calling
       conventions.

       You can add your own expansion macros by pushing an expansion manipulating the array

        @PDL::VectorValued::Dev::MACROS

       which is just a list of expansion subroutines which take a single argument (string for
       Code or BadCode) and should return the expanded string.

Type Utilities

   vv_indx_sig()
       Returns a signature type for representing PDL indices.  For PDL >= v2.007 this should be
       "PDL_Indx", otherwise it will be "int".

   vv_indx_typedef()
       Returns a C typedef for the "PDL_Indx" type if running under PDL <= v2.007, otherwise just
       a comment.  You can call this from client PDL::PP modules as

        pp_addhdr(PDL::VectorValued::Dev::vv_indx_typedef);

Macro Expansion Utilities

   vvpp_pdlvar_basename($pdlVarString)
       Gets basename of a PDL::PP variable by removing leading '$' and anything at or following
       the first open parenthesis:

        $base = vvpp_pdlvar_basename('$a(n=>0)'); ##-- $base is now 'a'

   vvpp_cmpvec_code($vec1,$vec2,$dimName,$retvar,%options)
       Returns PDL::PP code for lexicographically comparing two vectors $vec1 and $vec2 along the
       dimension named $dim, storing the comparison result in the C variable $retvar, similar to
       what:

        $retvar = ($vec1 <=> $vec2);

       "ought to" do.

       Parameters:

       $vec1
       $vec2
           PDL::PP string forms of vector PDLs to be compared.  Need not be physical.

       $dimName
           Name of the dimension along which vectors should be compared.

       $retvar
           Name of a C variable to store the comparison result.

       $options{cvar1}
       $options{cvar2}
           If specified, temporary values for $vec1 (rsp. $vec2) will be stored in the C variable
           $options{cvar1} (rsp. $options{cvar2}).  If unspecified, a new locally scoped C
           variable "_vvpp_cmpvec_val1" (rsp. "_vvpp_cmpvec_val2") will be declared and used.

       The PDL::PP code for cmpvec() looks something like this:

        use PDL::VectorValued::Dev;
        pp_def('cmpvec',
               Pars => 'a(n); b(n); int [o]cmp()',
               Code => (
                        'int cmpval;'
                        .vvpp_cmpvec_code( '$a()', '$b()', 'n', 'cmpval' )
                        .$cmp() = cmpval'
                       );
               );

   vvpp_cmpval_code($val1,$val2)
       Returns PDL::PP expression code for lexicographically comparing two values $val1 and
       $val2, storing the comparison result in the C variable $retvar, similar to what:

        ($vec1 <=> $vec2);

       "ought to" do.

       Parameters:

       $val1
       $val2
           PDL::PP string forms of values to be compared.  Need not be physical.

   vvpp_lb_code($find,$vals, $imin,$imax, $retvar, %options)
       Returns PDL::PP code for binary lower-bound search for the value $find() in the sorted pdl
       $vals($imin:$imax-1).  Parameters:

       $find
           Value to search for or PDL::PP string form of such a value.

       $vals
           PDL::PP string form of PDL to be searched. $vals should contain a placeholder $_
           representing the dimension to be searched.

       $retvar
           Name of a C variable to store the result.  On return, $retvar holds the maximum value
           for $_ in "$vals($imin:$imax-1)" such that "$vals($_=$retvar) <= $find" and
           "$vals($_=$j) < $find" for all $j with "$imin <= $j < $retvar", or $imin if no such
           value for $retvar exists, "$imin <= $retvar < $imax".  In other words, returns the
           least index $_ of a match for $find in $vals($imin:$imax-1) whenever a match exists,
           otherwise the greatest index whose value in $vals($imin:$imax-1) is strictly less than
           $find if that exists, and $imin if all values in $vals($imin:$imax-1) are strictly
           greater than $find.

       $options{lovar}
       $options{hivar}
       $options{midvar}
       $options{cmpvar}
           If specified, temporary indices and comparison values will be stored in the C
           variables $options{lovar}, $options{hivar}, $options{midvar}, and $options{cmpvar}.
           If unspecified, new locally scoped C variables "_vvpp_lb_loval" etc. will be declared
           and used.

       $options{ubmaxvar}
           If specified, should be a C variable to hold the index of the last inspected value for
           $_ in $vals($imin:$imax-1) strictly greater than $find.

   Low-Level Functions
       Some additional low-level functions are provided in the PDL::Ngrams::Utils package.  See
       PDL::Ngrams::Utils for details.

KNOWN BUGS

   Why not PDL::PP macros?
       All of these functions would be more intuitive if implemented directly as PDL::PP macros,
       and thus expanded directly by pp_def() rather than requiring vvpp_def().

       At the time of this module's writing, I was unable to figure out how to use the (then
       undocumented) PDL::PP macro expansion mechanism.  As of 2022, PDL::PP offers support for
       user-defined macros, and this module should be refactored to take advantage of that... but
       that hasn't happened yet.

ACKNOWLEDGEMENTS

       perl by Larry Wall.

AUTHOR

       Bryan Jurish <moocow@cpan.org>

       PDL by Karl Glazebrook, Tuomas J. Lukka, Christian Soeller, and others.

COPYRIGHT

       Copyright (c) 2007-2022, Bryan Jurish.  All rights reserved.

       This package is free software.  You may redistribute it and/or modify it under the same
       terms as Perl itself.

SEE ALSO

       perl(1), PDL::PP(3perl).