post-scarcity/src/ops/meta.c
2019-01-29 22:36:20 +00:00

46 lines
1.3 KiB
C

/*
* meta.c
*
* Get metadata from a cell which has it.
*
* (c) 2019 Simon Brooke <simon@journeyman.cc>
* Licensed under GPL version 2.0, or, at your option, any later version.
*/
#include "conspage.h"
#include "debug.h"
/**
* Function: get metadata describing my first argument.
*
* * (metadata any)
*
* @return a pointer to the metadata of my first argument, or nil if none.
*/
struct cons_pointer lisp_metadata( struct stack_frame *frame,
struct cons_pointer frame_pointer,
struct cons_pointer env ) {
debug_print( L"lisp_metadata: entered\n", DEBUG_EVAL );
debug_dump_object( frame->arg[0], DEBUG_EVAL );
struct cons_pointer result = NIL;
struct cons_space_object cell = pointer2cell( frame->arg[0] );
switch ( cell.tag.value ) {
case FUNCTIONTV:
result = cell.payload.function.meta;
break;
case SPECIALTV:
result = cell.payload.special.meta;
break;
case READTV:
case WRITETV:
result = cell.payload.stream.meta;
break;
}
return make_cons( make_cons( c_string_to_lisp_keyword( L"type" ),
c_type( frame->arg[0] ) ), result );
// return result;
}