meta.c

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/*
 * 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 "memory/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;
}