use b_plain

typedef char *keymap_t(void *)

def namespace_map_key(ns, key) ns->keymap ? ns->keymap(key) : key

struct namespace
	namespace *parent
	keymap_t *keymap
	hashtable hash

int namespace_buckets = 101

def namespace_init(ns)
	namespace_init(ns, NULL)
def namespace_init(ns, parent)
	namespace_init(ns, parent, NULL)
namespace_init(namespace *ns, namespace *parent, keymap_t *keymap)
	ns->parent = parent
	ns->keymap = keymap ? keymap : parent ? parent->keymap : NULL
	init(&ns->hash, hashtable, namespace_buckets)

namespace_free(namespace *ns)
	hashtable_free(&ns->hash)

namespace *namespace_child(namespace *ns)
	New(child, namespace, ns)
	return child

int lookup_max_depth = 64

def namespace_lookup(ns, key) namespace_lookup(ns, key, 0)

void *namespace_lookup(namespace *ns, void *key, int depth)
	cstr k = namespace_map_key(ns, key)
	if ++depth > lookup_max_depth
		error("namespace_lookup is caught in a loop while looking up %s", k)
	 # XXX this is repeated in parent namespaces,
	 # would they ever have different keymaps?
	let(kv, kv(&ns->hash, k))
	if kv
		return kv->v
	if ns->parent
		return namespace_lookup(ns->parent, key, depth)
	return NULL

void *namespace_lookup_skip(namespace *ns, void *key, int n)
	# this skips the first definition of something
	# and goes to the "next" one up, times n.
	if n == 0
		return namespace_lookup(ns, key)
	if !ns->parent
		return NULL
	cstr k = namespace_map_key(ns, key)
	let(kv, kv(&ns->hash, k))
	if kv
		--n
	return namespace_lookup_skip(ns->parent, key, n)

# use let, not set!
# set changes the meaning of the existing macro for parent scopes up to the last time it was defined but not above;
# probably NOT what you want.
#  ((WTF @ this)

# I could write a "kill" function and a "SET" function to completely redefine a macro for everyone, but YAGNI ATM

namespace_set(namespace *ns, void *key, void *val)
	cstr k = namespace_map_key(ns, key)
	set(&ns->hash, Strdup(k), val)
#	NOTE The perl has this which was not used:
#	$self->{hash_order}{$k} = $self->{counter}

namespace *namespace_let(namespace *ns, void *key, void *val)
	cstr k = namespace_map_key(ns, key)
	let(kv, kv(&ns->hash, k, val))
	if kv->v != val
		ns = namespace_child(ns)
		set(&ns->hash, Strdup(k), val)
	return ns

namespace *namespace_delete(namespace *ns, void *key)
	return namespace_let(ns, key, NULL)

boolean namespace_defined(namespace *ns, void *key)
	return namespace_lookup(ns, key) != NULL