112 lines
4.1 KiB
C
112 lines
4.1 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/pso4.h"
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#include "memory/tags.h"
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#include "payloads/stack.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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#include "payloads/stack.h"
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/**
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* @brief reverse a sequence
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*
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* (reverse sequence)
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*/
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struct pso_pointer reverse( struct pso_pointer frame_pointer ) {
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struct pso_pointer result = nil;
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struct pso_pointer sequence =
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fetch_arg( pointer_to_pso4( frame_pointer ), 0 );
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for ( struct pso_pointer cursor = sequence; !c_nilp( cursor );
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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 = push_local( frame_pointer,
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make_cons( frame_pointer, c_car( cursor ),
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result ) );
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break;
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case KEYTV:
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result = push_local( frame_pointer,
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make_string_like_thing( frame_pointer,
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object->payload.
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string.character,
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result,
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KEYTAG ) );
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break;
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case STRINGTV:
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result = push_local( frame_pointer,
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make_string_like_thing( frame_pointer,
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object->payload.
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string.character,
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result,
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STRINGTAG ) );
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break;
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case SYMBOLTV:
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result = push_local( frame_pointer,
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make_string_like_thing( frame_pointer,
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object->payload.
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string.character,
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result,
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SYMBOLTAG ) );
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break;
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default:
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result = push_local( frame_pointer,
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make_exception( make_frame
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( 1, frame_pointer,
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make_cons
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( frame_pointer,
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c_string_to_lisp_string
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( frame_pointer,
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L"Invalid object in sequence" ),
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cursor ) ) ) );
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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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/**
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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 frame_pointer,
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struct pso_pointer sequence ) {
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struct pso_pointer result = nil;
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if ( stackp( frame_pointer ) ) {
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result = reverse( make_frame(1, frame_pointer, sequence) );
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}
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return result;
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}
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