355 lines
8.0 KiB
C
355 lines
8.0 KiB
C
/**
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* See Copyright Notice in picrin.h
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*/
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#include "picrin.h"
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#include "picrin/object.h"
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KHASH_DEFINE(env, pic_id *, pic_sym *, kh_ptr_hash_func, kh_ptr_hash_equal)
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struct pic_env *
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pic_make_env(pic_state *pic, struct pic_env *up)
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{
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struct pic_env *env;
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assert(up != NULL);
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env = (struct pic_env *)pic_obj_alloc(pic, sizeof(struct pic_env), PIC_TYPE_ENV);
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env->up = up;
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env->lib = NULL;
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kh_init(env, &env->map);
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return env;
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}
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pic_sym *
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pic_add_identifier(pic_state *pic, pic_id *id, struct pic_env *env)
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{
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const char *name;
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pic_sym *uid;
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pic_value str;
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name = pic_str(pic, pic_id_name(pic, id));
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if (env->up == NULL && pic_sym_p(pic, pic_obj_value(id))) { /* toplevel & public */
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str = pic_strf_value(pic, "%s/%s", pic_str(pic, pic_obj_value(env->lib)), name);
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} else {
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str = pic_strf_value(pic, ".%s.%d", name, pic->ucnt++);
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}
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uid = pic_intern(pic, str);
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return pic_put_identifier(pic, id, uid, env);
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}
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pic_sym *
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pic_put_identifier(pic_state *pic, pic_id *id, pic_sym *uid, struct pic_env *env)
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{
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khiter_t it;
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int ret;
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it = kh_put(env, &env->map, id, &ret);
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kh_val(&env->map, it) = uid;
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return uid;
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}
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pic_sym *
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search_scope(pic_state *pic, pic_id *id, struct pic_env *env)
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{
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khiter_t it;
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it = kh_get(env, &env->map, id);
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if (it == kh_end(&env->map)) {
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return NULL;
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}
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return kh_val(&env->map, it);
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}
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static pic_sym *
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search(pic_state *pic, pic_id *id, struct pic_env *env)
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{
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pic_sym *uid = NULL;
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while (env != NULL) {
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uid = search_scope(pic, id, env);
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if (uid != NULL) {
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break;
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}
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env = env->up;
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}
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return uid;
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}
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pic_sym *
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pic_find_identifier(pic_state *pic, pic_id *id, struct pic_env *env)
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{
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pic_sym *uid;
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while ((uid = search(pic, id, env)) == NULL) {
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if (pic_sym_p(pic, pic_obj_value(id))) {
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break;
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}
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env = id->u.id.env; /* do not overwrite id first */
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id = id->u.id.id;
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}
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if (uid == NULL) {
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while (env->up != NULL) {
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env = env->up;
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}
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uid = pic_add_identifier(pic, id, env);
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}
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return uid;
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}
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/**
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* macro expander
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*/
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static void
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define_macro(pic_state *pic, pic_sym *uid, pic_value mac)
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{
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if (pic_weak_has(pic, pic->macros, uid)) {
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pic_warnf(pic, "redefining syntax variable: ~s", pic_obj_value(uid));
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}
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pic_weak_set(pic, pic->macros, uid, mac);
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}
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static pic_value
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find_macro(pic_state *pic, pic_sym *uid)
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{
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if (! pic_weak_has(pic, pic->macros, uid)) {
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return pic_false_value(pic);
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}
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return pic_weak_ref(pic, pic->macros, uid);
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}
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static void
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shadow_macro(pic_state *pic, pic_sym *uid)
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{
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if (pic_weak_has(pic, pic->macros, uid)) {
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pic_weak_del(pic, pic->macros, uid);
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}
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}
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static pic_value expand(pic_state *, pic_value, struct pic_env *, pic_value);
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static pic_value expand_lambda(pic_state *, pic_value, struct pic_env *);
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static pic_value
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expand_var(pic_state *pic, pic_id *id, struct pic_env *env, pic_value deferred)
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{
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pic_value mac;
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pic_sym *functor;
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functor = pic_find_identifier(pic, id, env);
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if (! pic_false_p(pic, mac = find_macro(pic, functor))) {
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return expand(pic, pic_call(pic, mac, 2, pic_obj_value(id), pic_obj_value(env)), env, deferred);
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}
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return pic_obj_value(functor);
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}
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static pic_value
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expand_quote(pic_state *pic, pic_value expr)
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{
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return pic_cons(pic, pic_obj_value(pic->sQUOTE), pic_cdr(pic, expr));
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}
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static pic_value
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expand_list(pic_state *pic, pic_value obj, struct pic_env *env, pic_value deferred)
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{
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size_t ai = pic_enter(pic);
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pic_value x, head, tail;
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if (pic_pair_p(pic, obj)) {
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head = expand(pic, pic_car(pic, obj), env, deferred);
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tail = expand_list(pic, pic_cdr(pic, obj), env, deferred);
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x = pic_cons(pic, head, tail);
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} else {
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x = expand(pic, obj, env, deferred);
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}
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pic_leave(pic, ai);
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pic_protect(pic, x);
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return x;
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}
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static pic_value
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expand_defer(pic_state *pic, pic_value expr, pic_value deferred)
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{
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pic_value skel = pic_cons(pic, pic_invalid_value(), pic_invalid_value());
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pic_set_car(pic, deferred, pic_cons(pic, pic_cons(pic, expr, skel), pic_car(pic, deferred)));
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return skel;
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}
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static void
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expand_deferred(pic_state *pic, pic_value deferred, struct pic_env *env)
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{
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pic_value defer, val, src, dst, it;
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deferred = pic_car(pic, deferred);
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pic_for_each (defer, pic_reverse(pic, deferred), it) {
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src = pic_car(pic, defer);
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dst = pic_cdr(pic, defer);
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val = expand_lambda(pic, src, env);
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/* copy */
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pic_set_car(pic, dst, pic_car(pic, val));
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pic_set_cdr(pic, dst, pic_cdr(pic, val));
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}
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}
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static pic_value
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expand_lambda(pic_state *pic, pic_value expr, struct pic_env *env)
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{
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pic_value formal, body;
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struct pic_env *in;
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pic_value a, deferred;
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in = pic_make_env(pic, env);
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for (a = pic_cadr(pic, expr); pic_pair_p(pic, a); a = pic_cdr(pic, a)) {
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pic_add_identifier(pic, pic_id_ptr(pic_car(pic, a)), in);
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}
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if (pic_id_p(pic, a)) {
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pic_add_identifier(pic, pic_id_ptr(a), in);
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}
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deferred = pic_list(pic, 1, pic_nil_value(pic));
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formal = expand_list(pic, pic_list_ref(pic, expr, 1), in, deferred);
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body = expand(pic, pic_list_ref(pic, expr, 2), in, deferred);
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expand_deferred(pic, deferred, in);
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return pic_list(pic, 3, pic_obj_value(pic->sLAMBDA), formal, body);
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}
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static pic_value
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expand_define(pic_state *pic, pic_value expr, struct pic_env *env, pic_value deferred)
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{
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pic_sym *uid;
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pic_id *id;
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pic_value val;
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id = pic_id_ptr(pic_cadr(pic, expr));
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if ((uid = search_scope(pic, id, env)) == NULL) {
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uid = pic_add_identifier(pic, id, env);
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} else {
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shadow_macro(pic, uid);
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}
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val = expand(pic, pic_list_ref(pic, expr, 2), env, deferred);
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return pic_list(pic, 3, pic_obj_value(pic->sDEFINE), pic_obj_value(uid), val);
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}
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static pic_value
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expand_defmacro(pic_state *pic, pic_value expr, struct pic_env *env)
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{
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pic_value pic_compile(pic_state *, pic_value);
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pic_id *id;
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pic_value val;
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pic_sym *uid;
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id = pic_id_ptr(pic_cadr(pic, expr));
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if ((uid = search_scope(pic, id, env)) == NULL) {
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uid = pic_add_identifier(pic, id, env);
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}
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val = pic_call(pic, pic_compile(pic, pic_expand(pic, pic_list_ref(pic, expr, 2), env)), 0);
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if (! pic_proc_p(pic, val)) {
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pic_errorf(pic, "macro definition \"%s\" evaluates to non-procedure object", pic_str(pic, pic_id_name(pic, id)));
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}
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define_macro(pic, uid, val);
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return pic_undef_value(pic);
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}
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static pic_value
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expand_node(pic_state *pic, pic_value expr, struct pic_env *env, pic_value deferred)
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{
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switch (pic_type(pic, expr)) {
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case PIC_TYPE_ID:
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case PIC_TYPE_SYMBOL: {
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return expand_var(pic, pic_id_ptr(expr), env, deferred);
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}
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case PIC_TYPE_PAIR: {
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pic_value mac;
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if (! pic_list_p(pic, expr)) {
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pic_errorf(pic, "cannot expand improper list: ~s", expr);
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}
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if (pic_id_p(pic, pic_car(pic, expr))) {
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pic_sym *functor;
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functor = pic_find_identifier(pic, pic_id_ptr(pic_car(pic, expr)), env);
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if (functor == pic->sDEFINE_MACRO) {
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return expand_defmacro(pic, expr, env);
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}
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else if (functor == pic->sLAMBDA) {
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return expand_defer(pic, expr, deferred);
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}
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else if (functor == pic->sDEFINE) {
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return expand_define(pic, expr, env, deferred);
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}
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else if (functor == pic->sQUOTE) {
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return expand_quote(pic, expr);
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}
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if (! pic_false_p(pic, mac = find_macro(pic, functor))) {
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return expand(pic, pic_call(pic, mac, 2, expr, pic_obj_value(env)), env, deferred);
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}
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}
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return expand_list(pic, expr, env, deferred);
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}
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default:
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return expr;
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}
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}
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static pic_value
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expand(pic_state *pic, pic_value expr, struct pic_env *env, pic_value deferred)
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{
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size_t ai = pic_enter(pic);
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pic_value v;
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v = expand_node(pic, expr, env, deferred);
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pic_leave(pic, ai);
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pic_protect(pic, v);
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return v;
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}
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pic_value
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pic_expand(pic_state *pic, pic_value expr, struct pic_env *env)
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{
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pic_value v, deferred;
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#if DEBUG
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puts("before expand:");
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pic_debug(pic, expr);
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puts("");
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#endif
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deferred = pic_list(pic, 1, pic_nil_value(pic));
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v = expand(pic, expr, env, deferred);
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expand_deferred(pic, deferred, env);
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#if DEBUG
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puts("after expand:");
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pic_debug(pic, v);
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puts("");
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#endif
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return v;
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}
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