Simon Brooke
f915a9993f
But did that by switching away from using Lisp calling convention, because that broke horribly. This is bad news and must be sorted out.
77 lines
2.4 KiB
C
77 lines
2.4 KiB
C
/**
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* ops/reverse.c
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*
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* Post Scarcity Software Environment: reverse.
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*
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* Reverse a sequence. Didn'e want to do this in the substrate, but I need
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* if for reading atoms!.
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*
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* (c) 2026 Simon Brooke <simon@journeyman.cc>
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* Licensed under GPL version 2.0, or, at your option, any later version.
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*/
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#include <stdbool.h>
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#include "memory/node.h"
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#include "memory/pointer.h"
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#include "memory/pso.h"
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#include "memory/pso2.h"
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#include "memory/tags.h"
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#include "payloads/cons.h"
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#include "payloads/exception.h"
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#include "payloads/psse_string.h"
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#include "ops/string_ops.h"
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#include "ops/truth.h"
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/**
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* @brief reverse a sequence.
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*
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* A sequence is a list or a string-like-thing. A dotted pair is not a
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* sequence.
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*
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* @param sequence a pointer to a sequence.
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* @return a sequence like the `sequence` passed, but reversed; or `nil` if
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* the argument was not a sequence.
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*/
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struct pso_pointer c_reverse( struct pso_pointer sequence ) {
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struct pso_pointer result = nil;
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for ( struct pso_pointer cursor = sequence; !nilp( sequence );
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cursor = c_cdr( cursor ) ) {
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struct pso2 *object = pointer_to_object( cursor );
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switch ( get_tag_value( cursor ) ) {
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case CONSTV:
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result = c_cons( c_car( cursor ), result );
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break;
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case KEYTV:
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// TODO: should you be able to reverse keywords and symbols?
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result =
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make_string_like_thing( object->payload.string.character,
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result, KEYTAG );
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break;
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case STRINGTV:
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result =
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make_string_like_thing( object->payload.string.character,
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result, STRINGTAG );
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break;
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case SYMBOLTV:
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// TODO: should you be able to reverse keywords and symbols?
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result =
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make_string_like_thing( object->payload.string.character,
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result, SYMBOLTAG );
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break;
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default:
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result =
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make_exception( c_string_to_lisp_string
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( L"Invalid object in sequence" ), nil,
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nil );
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goto exit;
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break;
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}
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}
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exit:
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return result;
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}
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