90 lines
2.7 KiB
C
90 lines
2.7 KiB
C
/**
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* ops/assoc.c
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*
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* Post Scarcity Software Environment: assoc.
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*
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* Search a store for the value associated with a key.
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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/pso2.h"
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#include "memory/tags.h"
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#include "payloads/cons.h"
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#include "ops/eq.h"
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#include "ops/truth.h"
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/**
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* @brief: fundamental search function; only knows about association lists
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*
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* @param key a pointer indicating the key to search for;
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* @param store a pointer indicating the store to search;
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* @param return_key if a binding is found for `key` in `store`, if true
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* return the key found in the store, else return the value
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*
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* @return nil if no binding for `key` is found in `store`; otherwise, if
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* `return_key` is true, return the key from the store; else
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* return the binding.
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*/
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struct pso_pointer search( struct pso_pointer key,
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struct pso_pointer store, bool return_key ) {
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struct pso_pointer result = nil;
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bool found = false;
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if ( consp( store ) ) {
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for ( struct pso_pointer cursor = store;
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consp( store ) && found == false; cursor = cdr( cursor ) ) {
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struct pso_pointer pair = car( cursor );
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if ( consp( pair ) && c_equal( car( pair ), key ) ) {
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found = true;
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result = return_key ? car( pair ) : cdr( pair );
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}
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}
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}
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return result;
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}
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/**
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* @prief: bootstap layer assoc; only knows about association lists.
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*
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* @param key a pointer indicating the key to search for;
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* @param store a pointer indicating the store to search;
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*
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* @return a pointer to the value of the key in the store, or nil if not found
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*/
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struct pso_pointer assoc( struct pso_pointer key, struct pso_pointer store ) {
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return search( key, store, false );
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}
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/**
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* @prief: bootstap layer interned; only knows about association lists.
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*
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* @param key a pointer indicating the key to search for;
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* @param store a pointer indicating the store to search;
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*
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* @return a pointer to the copy of the key in the store, or nil if not found.
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*/
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struct pso_pointer interned( struct pso_pointer key, struct pso_pointer store ) {
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return search( key, store, true );
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}
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/**
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* @prief: bootstap layer interned; only knows about association lists.
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*
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* @param key a pointer indicating the key to search for;
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* @param store a pointer indicating the store to search;
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*
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* @return `true` if a pointer the key was found in the store..
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*/
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bool internedp( struct pso_pointer key, struct pso_pointer store ) {
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return !nilp( search( key, store, true ) );
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}
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