picrin/extlib/benz/var.c

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/**
* See Copyright Notice in picrin.h
*/
#include "picrin.h"
static pic_value
var_lookup(pic_state *pic, pic_value var)
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{
pic_value val, env, binding;
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val = pic_ref(pic, pic->PICRIN_BASE, "current-dynamic-environment");
if (pic_eq_p(val, var)) {
return pic_false_value();
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}
env = pic_apply0(pic, pic_proc_ptr(val));
while (! pic_nil_p(env)) {
binding = pic_car(pic, env);
while (! pic_nil_p(binding)) {
if (pic_eq_p(pic_caar(pic, binding), var)) {
return pic_car(pic, binding);
}
binding = pic_cdr(pic, binding);
}
env = pic_cdr(pic, env);
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}
return pic_false_value();
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}
static pic_value
var_call(pic_state *pic)
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{
struct pic_proc *self = pic_get_proc(pic);
pic_value val, tmp, box, conv;
int n;
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n = pic_get_args(pic, "|oo", &val, &tmp);
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box = var_lookup(pic, pic_obj_value(self));
if (! pic_test(box)) {
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box = pic_attr_ref(pic, pic_obj_value(self), "@@box");
}
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switch (n) {
case 0:
return pic_cdr(pic, box);
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case 1:
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conv = pic_attr_ref(pic, pic_obj_value(self), "@@converter");
if (pic_test(conv)) {
pic_assert_type(pic, conv, proc);
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val = pic_apply1(pic, pic_proc_ptr(conv), val);
}
pic_set_cdr(pic, box, val);
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return pic_none_value();
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case 2:
assert(pic_false_p(tmp));
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conv = pic_attr_ref(pic, pic_obj_value(self), "@@converter");
if (pic_test(conv)) {
pic_assert_type(pic, conv, proc);
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return pic_apply1(pic, pic_proc_ptr(conv), val);
} else {
return val;
}
}
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PIC_UNREACHABLE();
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}
struct pic_proc *
pic_make_var(pic_state *pic, pic_value init, struct pic_proc *conv)
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{
struct pic_proc *var;
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var = pic_make_proc(pic, var_call, "<var-call>");
pic_attr_set(pic, pic_obj_value(var), "@@box", pic_cons(pic, pic_false_value(), init));
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pic_attr_set(pic, pic_obj_value(var), "@@converter", conv ? pic_obj_value(conv) : pic_false_value());
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return var;
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}
static pic_value
pic_var_make_parameter(pic_state *pic)
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{
struct pic_proc *conv = NULL;
pic_value init;
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pic_get_args(pic, "o|l", &init, &conv);
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return pic_obj_value(pic_make_var(pic, init, conv));
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}
void
pic_init_var(pic_state *pic)
{
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pic_define_noexport(pic, "current-dynamic-environment", pic_false_value());
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pic_defun(pic, "make-parameter", pic_var_make_parameter);
pic_set(pic, pic->PICRIN_BASE, "current-dynamic-environment", pic_obj_value(pic_make_var(pic, pic_nil_value(), NULL)));
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}