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#include "eval.h"
#include <stdio.h>
#include <string.h>
#include "mem.h"
#include "print.h"
void free_rules_until(fuspel* new, fuspel* old) {
while (new != old) {
fuspel* _new = new->rest;
free_rewrite_rule(&new->rule);
my_free(new);
new = _new;
}
}
typedef struct replacements {
char* what;
expression* with;
struct replacements* rest;
} replacements;
void replace(char* name, expression* new, expression* expr) {
if (!expr)
return;
switch (expr->kind) {
case EXPR_NAME:
if (!strcmp(expr->var1, name)) {
cpy_expression(expr, new);
break;
}
case EXPR_INT:
break;
case EXPR_TUPLE:
case EXPR_LIST:
case EXPR_APP:
replace(name, new, expr->var1);
replace(name, new, expr->var2);
break;
}
}
void replace_all(replacements* repls, expression* expr) {
while (repls) {
replace(repls->what, repls->with, expr);
repls = repls->rest;
}
}
replacements* push_replacement(char* what, expression* with, replacements* rest) {
replacements* new = my_calloc(1, sizeof(replacements));
new->what = what;
new->with = my_calloc(1, sizeof(expression));
cpy_expression(new->with, with);
new->rest = rest;
return new;
}
void free_replacements(replacements* repls) {
if (repls) {
free_replacements(repls->rest);
repls->rest = NULL;
free_expression(repls->with);
my_free(repls->with);
my_free(repls);
}
}
unsigned match_expr(fuspel* rules, expression* to_match, expression* expr,
replacements** repls) {
unsigned matches;
if (to_match->kind != EXPR_NAME) {
expr = eval_rnf(rules, expr);
if (!expr)
return 0;
}
switch (to_match->kind) {
case EXPR_NAME:
*repls = push_replacement(to_match->var1, expr, *repls);
return 1;
case EXPR_INT:
matches = eq_expression(to_match, expr);
free_expression(expr);
my_free(expr);
return matches;
case EXPR_LIST:
if (!to_match->var1) {
matches = eq_expression(to_match, expr);
free_expression(expr);
my_free(expr);
return matches;
}
case EXPR_TUPLE:
if (to_match->kind != expr->kind) {
free_expression(expr);
my_free(expr);
return 0;
}
matches =
match_expr(rules, to_match->var1, expr->var1, repls) &&
match_expr(rules, to_match->var2, expr->var2, repls);
free_expression(expr);
my_free(expr);
return matches;
default:
free_expression(expr);
my_free(expr);
return 0;
}
}
unsigned match_rule(fuspel* rules, rewrite_rule* rule, expression* expr,
replacements** repls) {
expression** expr_args;
unsigned char i;
switch (expr->kind) {
case EXPR_NAME:
return (!strcmp(expr->var1, rule->name) &&
empty_args_list(rule->args)) ? 1 : 0;
case EXPR_APP:
expr_args = flatten_app_args(expr);
i = 0;
if (!strcmp(expr_args[0]->var1, rule->name)) {
expression* _expr = expr_args[++i];
arg_list* args = rule->args;
fuspel* _rules = rules;
while (!empty_args_list(args)) {
if (!match_expr(_rules, &args->elem, _expr, repls)) {
free_rules_until(_rules, rules);
my_free(expr_args);
return 0;
}
args = args->rest;
_expr = expr_args[++i];
if (!empty_args_list(args) && !_expr) {
free_rules_until(_rules, rules);
my_free(expr_args);
return 0;
}
}
my_free(expr_args);
return 1;
}
my_free(expr_args);
default:
return 0;
}
}
expression* eval_rnf(fuspel* rules, expression* expr) {
expression* result = my_calloc(1, sizeof(expression));
fuspel* _rules = rules;
replacements** repls = my_calloc(1, sizeof(replacements*));
switch (expr->kind) {
case EXPR_INT:
case EXPR_TUPLE:
case EXPR_LIST:
cpy_expression(result, expr);
break;
case EXPR_NAME:
case EXPR_APP:
while (_rules) {
if (match_rule(rules, &_rules->rule, expr, repls)) {
expression* old_result = result;
cpy_expression(result, &_rules->rule.rhs);
replace_all(*repls, result);
free_replacements(*repls);
my_free(repls);
result = eval_rnf(rules, old_result);
free_expression(old_result);
my_free(old_result);
return result;
}
free_replacements(*repls);
my_free(repls);
repls = my_calloc(1, sizeof(replacements*));
_rules = _rules->rest;
}
cpy_expression(result, expr);
break;
}
free_replacements(*repls);
my_free(repls);
return result;
}
expression* eval(fuspel* rules, expression* expr) {
expression *e1, *e2;
fuspel* _rules = rules;
expression* result = my_calloc(1, sizeof(expression));
replacements** repls = my_calloc(1, sizeof(replacements*));
switch (expr->kind) {
case EXPR_INT:
cpy_expression(result, expr);
break;
case EXPR_NAME:
case EXPR_APP:
while (_rules) {
if (match_rule(rules, &_rules->rule, expr, repls)) {
expression* old_result = result;
cpy_expression(result, &_rules->rule.rhs);
replace_all(*repls, result);
result = eval(rules, result);
free_expression(old_result);
my_free(old_result);
free_replacements(*repls);
my_free(repls);
return result;
}
free_replacements(*repls);
my_free(repls);
repls = my_calloc(1, sizeof(replacements*));
_rules = _rules->rest;
}
cpy_expression(result, expr);
break;
case EXPR_LIST:
if (!expr->var1) {
cpy_expression(result, expr);
break;
}
case EXPR_TUPLE:
e1 = eval(rules, expr->var1);
e2 = eval(rules, expr->var2);
result->kind = expr->kind;
result->var1 = e1;
result->var2 = e2;
break;
}
free_replacements(*repls);
my_free(repls);
return result;
}
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