Module hat.duktape
Python ctypes wrapper for duktape JavaScript interpreter
Expand source code
"""Python ctypes wrapper for duktape JavaScript interpreter"""
from pathlib import Path
import ctypes
import sys
class Interpreter:
"""JavaScript interpreter
High-level python wrapper to duktape JavaScript interpreter.
Current implementation caches all function objects for preventing
garbage collection.
"""
def __init__(self):
@_lib.duk_fatal_function
def fatal_handler(udata, msg):
try:
print(f"duktape fatal error: {msg.decode('utf-8')}")
finally:
sys.exit(1)
self._ctx = _lib.duk_create_heap(None, None, None, None, fatal_handler)
self._fns = [fatal_handler]
def __del__(self):
_lib.duk_destroy_heap(self._ctx)
self._fns = []
def eval(self, code):
"""Evaluate JS code
Args:
code (str): JS code
Returns:
Any
"""
top = _lib.duk_get_top(self._ctx)
try:
_lib.duk_eval_string(self._ctx, code.encode('utf-8'))
return self._peek(-1)
finally:
_lib.duk_set_top(self._ctx, top)
def get(self, name):
"""Get global value
Args:
name (str): global name
Returns:
Any
"""
top = _lib.duk_get_top(self._ctx)
try:
key = name.encode('utf-8')
_lib.duk_get_global_string(self._ctx, key)
return self._peek(-1)
finally:
_lib.duk_set_top(self._ctx, top)
def set(self, name, value):
"""Set global value
Args:
name (str): global name
value (Any): value
"""
top = _lib.duk_get_top(self._ctx)
try:
self._push(value)
key = name.encode('utf-8')
_lib.duk_put_global_string(self._ctx, key)
finally:
_lib.duk_set_top(self._ctx, top)
def _peek(self, idx):
if _lib.duk_is_null_or_undefined(self._ctx, idx):
return
if _lib.duk_is_boolean(self._ctx, idx):
return self._peek_boolean(idx)
if _lib.duk_is_number(self._ctx, idx):
return self._peek_number(idx)
if _lib.duk_is_string(self._ctx, idx):
return self._peek_string(idx)
if _lib.duk_is_array(self._ctx, idx):
return self._peek_array(idx)
if _lib.duk_is_function(self._ctx, idx):
return self._peek_function(idx)
if _lib.duk_is_object(self._ctx, idx):
return self._peek_object(idx)
raise ValueError()
def _peek_boolean(self, idx):
return bool(_lib.duk_get_boolean(self._ctx, idx))
def _peek_number(self, idx):
return _lib.duk_get_number(self._ctx, idx)
def _peek_string(self, idx):
return _lib.duk_get_string(self._ctx, idx).decode('utf-8')
def _peek_array(self, idx):
result = []
top = _lib.duk_get_top(self._ctx)
_lib.duk_enum(self._ctx, idx, _lib.DUK_ENUM_ARRAY_INDICES_ONLY)
try:
while _lib.duk_next(self._ctx, top, 1):
result.append(self._peek(-1))
finally:
_lib.duk_set_top(self._ctx, top)
return result
def _peek_object(self, idx):
result = {}
top = _lib.duk_get_top(self._ctx)
_lib.duk_enum(self._ctx, idx, _lib.DUK_ENUM_OWN_PROPERTIES_ONLY)
try:
while _lib.duk_next(self._ctx, top, 1):
key = self._peek(-2)
value = self._peek(-1)
result[key] = value
finally:
_lib.duk_set_top(self._ctx, top)
return result
def _peek_function(self, idx):
fn_ptr = _lib.duk_get_heapptr(self._ctx, idx)
self._stash(fn_ptr)
def wrapper(*args):
top = _lib.duk_push_heapptr(self._ctx, fn_ptr)
try:
for arg in args:
self._push(arg)
_lib.duk_call(self._ctx, len(args))
return self._peek(-1)
finally:
_lib.duk_set_top(self._ctx, top)
return wrapper
def _push(self, value):
if value is None:
self._push_null()
elif isinstance(value, bool):
self._push_boolean(value)
elif isinstance(value, int) or isinstance(value, float):
self._push_number(value)
elif isinstance(value, str):
self._push_string(value)
elif isinstance(value, list) or isinstance(value, tuple):
self._push_array(value)
elif isinstance(value, dict):
self._push_object(value)
elif callable(value):
self._push_function(value)
else:
raise ValueError()
def _push_null(self):
_lib.duk_push_null(self._ctx)
def _push_boolean(self, value):
_lib.duk_push_boolean(self._ctx, value)
def _push_number(self, value):
_lib.duk_push_number(self._ctx, value)
def _push_string(self, value):
_lib.duk_push_string(self._ctx, value.encode('utf-8'))
def _push_array(self, value):
arr_idx = _lib.duk_push_array(self._ctx)
try:
for index, element in enumerate(value):
self._push(element)
if _lib.duk_put_prop_index(self._ctx, arr_idx,
index) != 1:
raise Exception('could not add element to array')
except Exception:
_lib.duk_set_top(self._ctx, arr_idx)
raise
def _push_object(self, value):
obj_idx = _lib.duk_push_object(self._ctx)
try:
for k, v in value.items():
self._push(v)
if _lib.duk_put_prop_string(self._ctx, obj_idx,
k.encode('utf-8')) != 1:
raise Exception('could not add property to object')
except Exception:
_lib.duk_set_top(self._ctx, obj_idx)
raise
def _push_function(self, value):
@_lib.duk_c_function
def wrapper(ctx):
args = []
args_count = _lib.duk_get_top(self._ctx)
try:
for i in range(args_count):
args.append(self._peek(i))
result = value(*args)
self._push(result)
except Exception:
return _lib.DUK_RET_ERROR
return 1
_lib.duk_push_c_function(self._ctx, wrapper, _lib.DUK_VARARGS)
self._fns.append(wrapper)
def _stash(self, ptr):
top = _lib.duk_get_top(self._ctx)
try:
ptr_id = int(ptr)
_lib.duk_push_heap_stash(self._ctx)
_lib.duk_push_heapptr(self._ctx, ptr)
if _lib.duk_put_prop_index(self._ctx, -2, ptr_id) != 1:
raise Exception("couldn't stash pointer")
finally:
_lib.duk_set_top(self._ctx, top)
class _Lib:
def __init__(self, path):
lib = ctypes.cdll.LoadLibrary(str(path))
self._init_functions(lib)
self._init_constants(lib)
def _init_functions(self, lib):
duk_size_t = ctypes.c_size_t
duk_int_t = ctypes.c_int
duk_uint_t = ctypes.c_uint
duk_small_int_t = ctypes.c_int
duk_small_uint_t = ctypes.c_uint
duk_bool_t = duk_small_uint_t
duk_idx_t = duk_int_t
duk_uarridx_t = duk_uint_t
duk_ret_t = duk_small_int_t
duk_double_t = ctypes.c_double
duk_context_p = ctypes.c_void_p
self.duk_c_function = ctypes.CFUNCTYPE(duk_ret_t,
duk_context_p)
self.duk_fatal_function = ctypes.CFUNCTYPE(None,
ctypes.c_void_p,
ctypes.c_char_p)
functions = [
(None, 'duk_call', [duk_context_p,
duk_idx_t]),
(duk_context_p, 'duk_create_heap', [ctypes.c_void_p,
ctypes.c_void_p,
ctypes.c_void_p,
ctypes.c_void_p,
self.duk_fatal_function]),
(None, 'duk_destroy_heap', [duk_context_p]),
(None, 'duk_enum', [duk_context_p,
duk_idx_t,
duk_uint_t]),
(duk_int_t, 'duk_eval_raw', [duk_context_p,
ctypes.c_char_p,
duk_size_t,
duk_uint_t]),
(duk_bool_t, 'duk_get_boolean', [duk_context_p,
duk_idx_t]),
(duk_bool_t, 'duk_get_global_string', [duk_context_p,
ctypes.c_char_p]),
(ctypes.c_void_p, 'duk_get_heapptr', [duk_context_p,
duk_idx_t]),
(duk_double_t, 'duk_get_number', [duk_context_p,
duk_idx_t]),
(ctypes.c_char_p, 'duk_get_string', [duk_context_p,
duk_idx_t]),
(duk_idx_t, 'duk_get_top', [duk_context_p]),
(duk_uint_t, 'duk_get_type_mask', [duk_context_p,
duk_idx_t]),
(duk_bool_t, 'duk_is_array', [duk_context_p,
duk_idx_t]),
(duk_bool_t, 'duk_is_boolean', [duk_context_p,
duk_idx_t]),
(duk_bool_t, 'duk_is_function', [duk_context_p,
duk_idx_t]),
(duk_bool_t, 'duk_is_number', [duk_context_p,
duk_idx_t]),
(duk_bool_t, 'duk_is_object', [duk_context_p,
duk_idx_t]),
(duk_bool_t, 'duk_is_string', [duk_context_p,
duk_idx_t]),
(duk_bool_t, 'duk_next', [duk_context_p,
duk_idx_t,
duk_bool_t]),
(duk_idx_t, 'duk_push_array', [duk_context_p]),
(None, 'duk_push_boolean', [duk_context_p,
duk_bool_t]),
(duk_idx_t, 'duk_push_c_function', [duk_context_p,
self.duk_c_function,
duk_idx_t]),
(duk_idx_t, 'duk_push_heapptr', [duk_context_p,
ctypes.c_void_p]),
(None, 'duk_push_heap_stash', [duk_context_p]),
(None, 'duk_push_null', [duk_context_p]),
(None, 'duk_push_number', [duk_context_p,
duk_double_t]),
(duk_idx_t, 'duk_push_object', [duk_context_p]),
(ctypes.c_char_p, 'duk_push_string', [duk_context_p,
ctypes.c_char_p]),
(duk_bool_t, 'duk_put_global_string', [duk_context_p,
ctypes.c_char_p]),
(duk_bool_t, 'duk_put_prop_index', [duk_context_p,
duk_idx_t,
duk_uarridx_t]),
(duk_bool_t, 'duk_put_prop_string', [duk_context_p,
duk_idx_t,
ctypes.c_char_p]),
(None, 'duk_set_top', [duk_context_p,
duk_idx_t])
]
for restype, name, argtypes in functions:
function = getattr(lib, name)
function.argtypes = argtypes
function.restype = restype
setattr(self, name, function)
def _init_constants(self, lib):
DUK_ERR_ERROR = 1
DUK_COMPILE_EVAL = (1 << 3)
DUK_COMPILE_NOSOURCE = (1 << 9)
DUK_COMPILE_STRLEN = (1 << 10)
DUK_COMPILE_NOFILENAME = (1 << 11)
DUK_TYPE_MASK_UNDEFINED = (1 << 1)
DUK_TYPE_MASK_NULL = (1 << 2)
self.DUK_ENUM_OWN_PROPERTIES_ONLY = (1 << 4)
self.DUK_ENUM_ARRAY_INDICES_ONLY = (1 << 5)
self.DUK_VARARGS = -1
self.DUK_RET_ERROR = - DUK_ERR_ERROR
self.duk_eval_string = lambda ctx, src: lib.duk_eval_raw(
ctx, src, 0,
0 | DUK_COMPILE_EVAL | DUK_COMPILE_NOSOURCE |
DUK_COMPILE_STRLEN | DUK_COMPILE_NOFILENAME)
self.duk_is_null_or_undefined = lambda ctx, idx: bool(
lib.duk_get_type_mask(ctx, idx) &
(DUK_TYPE_MASK_NULL | DUK_TYPE_MASK_UNDEFINED))
if sys.platform == 'win32':
_lib_suffix = '.dll'
elif sys.platform == 'darwin':
_lib_suffix = '.dylib'
else:
_lib_suffix = '.so'
_lib = _Lib(Path(__file__).parent / f'duktape{_lib_suffix}')Classes
class Interpreter-
JavaScript interpreter
High-level python wrapper to duktape JavaScript interpreter.
Current implementation caches all function objects for preventing garbage collection.
Expand source code
class Interpreter: """JavaScript interpreter High-level python wrapper to duktape JavaScript interpreter. Current implementation caches all function objects for preventing garbage collection. """ def __init__(self): @_lib.duk_fatal_function def fatal_handler(udata, msg): try: print(f"duktape fatal error: {msg.decode('utf-8')}") finally: sys.exit(1) self._ctx = _lib.duk_create_heap(None, None, None, None, fatal_handler) self._fns = [fatal_handler] def __del__(self): _lib.duk_destroy_heap(self._ctx) self._fns = [] def eval(self, code): """Evaluate JS code Args: code (str): JS code Returns: Any """ top = _lib.duk_get_top(self._ctx) try: _lib.duk_eval_string(self._ctx, code.encode('utf-8')) return self._peek(-1) finally: _lib.duk_set_top(self._ctx, top) def get(self, name): """Get global value Args: name (str): global name Returns: Any """ top = _lib.duk_get_top(self._ctx) try: key = name.encode('utf-8') _lib.duk_get_global_string(self._ctx, key) return self._peek(-1) finally: _lib.duk_set_top(self._ctx, top) def set(self, name, value): """Set global value Args: name (str): global name value (Any): value """ top = _lib.duk_get_top(self._ctx) try: self._push(value) key = name.encode('utf-8') _lib.duk_put_global_string(self._ctx, key) finally: _lib.duk_set_top(self._ctx, top) def _peek(self, idx): if _lib.duk_is_null_or_undefined(self._ctx, idx): return if _lib.duk_is_boolean(self._ctx, idx): return self._peek_boolean(idx) if _lib.duk_is_number(self._ctx, idx): return self._peek_number(idx) if _lib.duk_is_string(self._ctx, idx): return self._peek_string(idx) if _lib.duk_is_array(self._ctx, idx): return self._peek_array(idx) if _lib.duk_is_function(self._ctx, idx): return self._peek_function(idx) if _lib.duk_is_object(self._ctx, idx): return self._peek_object(idx) raise ValueError() def _peek_boolean(self, idx): return bool(_lib.duk_get_boolean(self._ctx, idx)) def _peek_number(self, idx): return _lib.duk_get_number(self._ctx, idx) def _peek_string(self, idx): return _lib.duk_get_string(self._ctx, idx).decode('utf-8') def _peek_array(self, idx): result = [] top = _lib.duk_get_top(self._ctx) _lib.duk_enum(self._ctx, idx, _lib.DUK_ENUM_ARRAY_INDICES_ONLY) try: while _lib.duk_next(self._ctx, top, 1): result.append(self._peek(-1)) finally: _lib.duk_set_top(self._ctx, top) return result def _peek_object(self, idx): result = {} top = _lib.duk_get_top(self._ctx) _lib.duk_enum(self._ctx, idx, _lib.DUK_ENUM_OWN_PROPERTIES_ONLY) try: while _lib.duk_next(self._ctx, top, 1): key = self._peek(-2) value = self._peek(-1) result[key] = value finally: _lib.duk_set_top(self._ctx, top) return result def _peek_function(self, idx): fn_ptr = _lib.duk_get_heapptr(self._ctx, idx) self._stash(fn_ptr) def wrapper(*args): top = _lib.duk_push_heapptr(self._ctx, fn_ptr) try: for arg in args: self._push(arg) _lib.duk_call(self._ctx, len(args)) return self._peek(-1) finally: _lib.duk_set_top(self._ctx, top) return wrapper def _push(self, value): if value is None: self._push_null() elif isinstance(value, bool): self._push_boolean(value) elif isinstance(value, int) or isinstance(value, float): self._push_number(value) elif isinstance(value, str): self._push_string(value) elif isinstance(value, list) or isinstance(value, tuple): self._push_array(value) elif isinstance(value, dict): self._push_object(value) elif callable(value): self._push_function(value) else: raise ValueError() def _push_null(self): _lib.duk_push_null(self._ctx) def _push_boolean(self, value): _lib.duk_push_boolean(self._ctx, value) def _push_number(self, value): _lib.duk_push_number(self._ctx, value) def _push_string(self, value): _lib.duk_push_string(self._ctx, value.encode('utf-8')) def _push_array(self, value): arr_idx = _lib.duk_push_array(self._ctx) try: for index, element in enumerate(value): self._push(element) if _lib.duk_put_prop_index(self._ctx, arr_idx, index) != 1: raise Exception('could not add element to array') except Exception: _lib.duk_set_top(self._ctx, arr_idx) raise def _push_object(self, value): obj_idx = _lib.duk_push_object(self._ctx) try: for k, v in value.items(): self._push(v) if _lib.duk_put_prop_string(self._ctx, obj_idx, k.encode('utf-8')) != 1: raise Exception('could not add property to object') except Exception: _lib.duk_set_top(self._ctx, obj_idx) raise def _push_function(self, value): @_lib.duk_c_function def wrapper(ctx): args = [] args_count = _lib.duk_get_top(self._ctx) try: for i in range(args_count): args.append(self._peek(i)) result = value(*args) self._push(result) except Exception: return _lib.DUK_RET_ERROR return 1 _lib.duk_push_c_function(self._ctx, wrapper, _lib.DUK_VARARGS) self._fns.append(wrapper) def _stash(self, ptr): top = _lib.duk_get_top(self._ctx) try: ptr_id = int(ptr) _lib.duk_push_heap_stash(self._ctx) _lib.duk_push_heapptr(self._ctx, ptr) if _lib.duk_put_prop_index(self._ctx, -2, ptr_id) != 1: raise Exception("couldn't stash pointer") finally: _lib.duk_set_top(self._ctx, top)Methods
def eval(self, code)-
Evaluate JS code
Args
code:str- JS code
Returns
Any
Expand source code
def eval(self, code): """Evaluate JS code Args: code (str): JS code Returns: Any """ top = _lib.duk_get_top(self._ctx) try: _lib.duk_eval_string(self._ctx, code.encode('utf-8')) return self._peek(-1) finally: _lib.duk_set_top(self._ctx, top) def get(self, name)-
Get global value
Args
name:str- global name
Returns
Any
Expand source code
def get(self, name): """Get global value Args: name (str): global name Returns: Any """ top = _lib.duk_get_top(self._ctx) try: key = name.encode('utf-8') _lib.duk_get_global_string(self._ctx, key) return self._peek(-1) finally: _lib.duk_set_top(self._ctx, top) def set(self, name, value)-
Set global value
Args
name:str- global name
value:Any- value
Expand source code
def set(self, name, value): """Set global value Args: name (str): global name value (Any): value """ top = _lib.duk_get_top(self._ctx) try: self._push(value) key = name.encode('utf-8') _lib.duk_put_global_string(self._ctx, key) finally: _lib.duk_set_top(self._ctx, top)