#include "eval.h"

#include "env.h"

#include <assert.h>

static void eval_atom(am_t *am)
{
	switch (am->expr->atom.type) {
	case ATOM_TYPE_EMPTY_LIST:
	case ATOM_TYPE_INTEGER:
	case ATOM_TYPE_PRIM_PROC:
		am->val = am->expr;
		break;
	case ATOM_TYPE_SYMBOL:
		env_fetch(am);
		break;
	}
}

static void eval_list(am_t *am)
{
	am->argl = am->expr->pair.cdr;
	am->expr = am->expr->pair.car;

	assert(am->expr->is_atom);
	assert(am->expr->atom.type == ATOM_TYPE_SYMBOL);
	env_fetch(am);

	assert(am->val->is_atom);
	assert(am->val->atom.type == ATOM_TYPE_PRIM_PROC);
	assert(am->val->atom.prim_proc != NULL);
	am->val->atom.prim_proc(am);
}

void eval(am_t *am)
{
	if (am->expr->is_atom)
		eval_atom(am);
	else
		eval_list(am);
}