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// Copyright (c) 2023, Marvin Borner <dev@marvinborner.de>
// SPDX-License-Identifier: MIT
#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
#include <log.h>
#include <term.h>
#include <map.h>
struct term *term_new(term_type_t type, hash_t hash, size_t depth)
{
struct term *term = malloc(sizeof(*term));
if (!term)
fatal("out of memory!\n");
term->type = type;
term->refs = 1;
term->hash = hash;
term->depth = depth;
term->parents = hashmap_new(sizeof(struct term *), 0, 0);
return term;
}
void term_print(struct term *term)
{
switch (term->type) {
case ABS:
fprintf(stderr, "[");
term_print(term->u.abs.term);
fprintf(stderr, "]");
break;
case APP:
fprintf(stderr, "(");
term_print(term->u.app.lhs);
fprintf(stderr, " ");
term_print(term->u.app.rhs);
fprintf(stderr, ")");
break;
case VAR:
fprintf(stderr, "%ld", term->u.var.index);
break;
default:
fatal("invalid type %d\n", term->type);
}
}
struct term *term_rehash_abs(struct term *head, struct term *term)
{
hash_t res =
hash((uint8_t *)&head->type, sizeof(head->type), term->hash);
if (res == head->hash)
return head;
struct term *match = map_get(map_all_terms(), res);
if (match) { // already exists
return match;
} else { // create new
struct term *new = term_new(ABS, res, head->depth);
new->u.abs.term = term;
map_set(map_all_terms(), new);
map_set(term->parents, new);
return new;
}
}
struct term *term_rehash_app(struct term *head, struct term *lhs,
struct term *rhs)
{
hash_t res =
hash((uint8_t *)&head->type, sizeof(head->type), lhs->hash);
res = hash((uint8_t *)&res, sizeof(res), rhs->hash);
if (res == head->hash)
return head;
struct term *match = map_get(map_all_terms(), res);
if (match) { // already exists
return match;
} else { // create new
struct term *new = term_new(APP, res, head->depth);
new->u.app.lhs = lhs;
new->u.app.rhs = rhs;
map_set(map_all_terms(), new);
map_set(lhs->parents, new);
map_set(rhs->parents, new);
return new;
}
}
struct term *term_rehash_var(struct term *head, size_t index)
{
hash_t res = hash((uint8_t *)&head->type, sizeof(head->type), index);
if (res == head->hash)
return head;
struct term *match = map_get(map_all_terms(), res);
if (match) { // already exists
return match;
} else { // create new
struct term *new = term_new(APP, res, head->depth);
new->u.var.index = index;
map_set(map_all_terms(), new);
return new;
}
}
struct term *term_rehash(struct term *term)
{
if (term->type == ABS) {
return term_rehash_abs(term, term->u.abs.term);
} else if (term->type == APP) {
return term_rehash_app(term, term->u.app.lhs, term->u.app.rhs);
} else if (term->type == VAR) {
return term_rehash_var(term, term->u.var.index);
}
return term;
}
// returns the direct parent
void term_rehash_parents(struct term *term)
{
if (!term->parents)
return;
// we need to convert the parent hashmap to a list
// so we can replace the rehashed elements while looping
// TODO: Abstract list lib?
struct parent_list {
struct term *term;
struct parent_list *next;
};
struct parent_list *parents = calloc(sizeof(*parents), 1);
size_t iter = 0;
void *iter_val;
while (hashmap_iter(term->parents, &iter, &iter_val)) {
struct parent_list *new = malloc(sizeof(*parents));
new->term = *(struct term **)iter_val;
new->next = parents;
parents = new;
}
struct parent_list *iterator = parents;
while (iterator && iterator->term) {
struct term *parent = iterator->term;
hash_t previous = parent->hash;
struct term *new = term_rehash(parent);
if (previous == new->hash) {
struct parent_list *next = iterator->next;
free(iterator);
iterator = next;
}
map_delete(term->parents, parent);
map_set(term->parents, new);
term_rehash_parents(new);
struct parent_list *next = iterator->next;
free(iterator);
iterator = next;
}
}
void term_refer_head(struct term *term, size_t depth)
{
term->refs++;
if (depth < term->depth) // lower depths are more important
term->depth = depth;
}
void term_refer(struct term *term, size_t depth)
{
if (term->type == ABS) {
term_refer(term->u.abs.term, depth + 1);
} else if (term->type == APP) {
term_refer(term->u.app.lhs, depth + 1);
term_refer(term->u.app.rhs, depth + 1);
}
term_refer_head(term, depth);
}
void term_deref_head(struct term *term)
{
term->refs--;
if (term->refs == 0) {
map_delete(map_all_terms(), term);
map_destroy(term->parents);
free(term);
}
}
void term_deref(struct term *term)
{
if (term->type == ABS) {
term_deref(term->u.abs.term);
} else if (term->type == APP) {
term_deref(term->u.app.lhs);
term_deref(term->u.app.rhs);
}
term_deref_head(term);
}
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