janet via python's ctypes

janet_via_ctypes.py

from ctypes import *

# macos may need .dylib
# windows may need WinDLL and .dll
dll = CDLL("./libjanet.so")

dll.janet_init()

# http://michas.eu/blog/c_ints.php?lang=en
# https://stackoverflow.com/a/13293860
class Janet(Union):
    _fields_ = [("u64", c_uint64), # uint64_t
                ("i64", c_int64), # int64_t
                ("number", c_double),
                ("pointer", c_void_p)]

class JanetKV(Structure):
    _fields_ = [("key", Janet),
                ("value", Janet)]

# https://stackoverflow.com/a/1228447
class JanetGCObject(Structure):
    pass

JanetGCObject._fields_ = \
    [("flags", c_int32),
     ("next", POINTER(JanetGCObject))]

class JanetTable(Structure):
    pass

JanetTable._fields_ = \
    [("gc", JanetGCObject),
     ("count", c_int32),
     ("capacity", c_int32),
     ("deleted", c_int32),
     ("data", POINTER(JanetKV)),
     ("proto", POINTER(JanetTable))]

# typedef const uint8_t *JanetSymbol;
# JANET_API JanetSymbol janet_symbol(const uint8_t *str, int32_t len);

dll.janet_symbol.restype = c_char_p

plus = dll.janet_symbol(c_char_p(bytes('+', "utf8")), 1)

dll.janet_core_env.restype = POINTER(JanetTable)

env = dll.janet_core_env(None)

env

env.contents

# JANET_API JanetKV *janet_table_find(JanetTable *t, Janet key);

dll.janet_table_find.restype = POINTER(JanetKV)

dll.janet_table_find(env, plus)

v = dll.janet_table_find(env, plus)

v.contents

v.contents.key

v.contents.value

dll.janet_dostring(env, c_char_p(bytes('(print "hi")', "utf8")), None, None)

out = Janet()

dll.janet_dostring(env, c_char_p(bytes('(+ 1 2)', "utf8")), None, byref(out))

out

# 0 means number - see JanetType
dll.janet_type(out)

dll.janet_unwrap_number.restype = c_double

dll.janet_unwrap_number(out)

dll.janet_deinit()

# thanks to ahungry for:
#   https://github.com/ahungry/puny-gui/blob/0f77f43b3adb88fd997e539c2daa1366602ad08d/app.c