BF-31 #8
BF-31 #8
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Early return would cause a negative pm.bigint not resetting back to negative
… to JS functions `JS_NewUCStringCopyN` only copies by the specified length `u16Length`, so no need to make another `memcpy` call
src/jsTypeFactory.cc
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| PyObject *const inspect = PyImport_Import(PyUnicode_DecodeFSDefault("inspect")); | ||
| PyObject *const getfullargspec = PyObject_GetAttrString(inspect, "getfullargspec"); | ||
| PyObject *const getfullargspecArgs = PyTuple_New(1); | ||
| PyTuple_SetItem(getfullargspecArgs, 0, object); | ||
| PyObject *const argspec = PyObject_CallObject(getfullargspec, getfullargspecArgs); | ||
| PyObject *const args = PyObject_GetAttrString(argspec, "args"); |
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memory leaks,
PyImport_Import, PyObject_GetAttrString, PyTuple_New and PyObject_CallObject all return a new reference
see https://pythonextensionpatterns.readthedocs.io/en/latest/refcount.html#memory-leaks
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Is there a real use of argument count in JS?
JS functions should be all variadic in nature. (Not verified yet)
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It might be used by the JIT compiler for optimization purposes, but apart from that I don't think so
src/jsTypeFactory.cc
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| PyObject *const inspect = PyImport_Import(PyUnicode_DecodeFSDefault("inspect")); | ||
| PyObject *const getfullargspec = PyObject_GetAttrString(inspect, "getfullargspec"); | ||
| PyObject *const getfullargspecArgs = PyTuple_New(1); | ||
| PyTuple_SetItem(getfullargspecArgs, 0, object); | ||
| PyObject *const argspec = PyObject_CallObject(getfullargspec, getfullargspecArgs); | ||
| PyObject *const args = PyObject_GetAttrString(argspec, "args"); | ||
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| JSFunction *jsFunc = js::NewFunctionWithReserved(cx, callPyFunc, PyList_Size(args), 0, NULL); |
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The maximum argument count in SpiderMonkey is 65535 (haven't tested yet)
https://hg.mozilla.org/releases/mozilla-esr102/file/tip/js/src/vm/JSFunction.cpp#l1895
What's the limit in CPython? Would nargs overflow?
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Did some research, looks like before python 3.7, maximum number of arguments is 255, after 3.7 maximum number of arguments is theoretically unbounded (though realistically its bounded by sys.maxsize, which is 2^64 - 1 on 64-bit architectures).
So I'm thinking we should error out if nargs > 65535. Thoughts?
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PythonMonkey can actually handle such huge amount (> 65535) of arguments to a variadic function
import pythonmonkey as pm
js_fn = pm.eval("(...args) => { return args.length }")
def py_fn(*args):
return len(args)
l = range(2**16+1)
print(py_fn(*l)) # 65537
print(js_fn(*l)) # 65537.0There was a problem hiding this comment.
SpiderMonkey's limit is actually 500k arguments
https://hg.mozilla.org/releases/mozilla-esr102/file/tip/js/src/vm/Stack.h#l879
if (argc > ARGS_LENGTH_MAX) {
JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
JSMSG_TOO_MANY_ARGUMENTS);
return false;
}https://hg.mozilla.org/releases/mozilla-esr102/file/tip/js/src/vm/ArgumentsObject.h#l95
// Maximum supported value of arguments.length. This bounds the
// maximum number of arguments that can be supplied to a spread call
// or Function.prototype.apply. This value also bounds the number of
// elements parsed in an array initializer. NB: keep this in sync
// with the copy in builtin/SelfHostingDefines.h.
static const unsigned ARGS_LENGTH_MAX = 500 * 1000;There was a problem hiding this comment.
Verified in PythonMonkey
import pythonmonkey as pm
js_fn = pm.eval("(...args) => { return args.length }")
def py_fn(*args):
return len(args)
l = range(500 * 1000)
print(py_fn(*l)) # 500000
print(js_fn(*l)) # 500000.0
l = range(500 * 1000 + 1)
print(py_fn(*l)) # 500001
print(js_fn(*l)) # pythonmonkey.SpiderMonkeyError: RangeError: too many arguments provided for a function callThere was a problem hiding this comment.
I don't think it's necessary to error it out because
- no one would write a Python function with more than 500k formal arguments
- SpiderMonkey would error it out when passing more than 500k arguments to a JS function
inspect.getfullargspec(py_fn).argsonly contains positional parameter names, returns a empty list for thepy_fnfunction above
Co-authored-by: Tom Wenzheng Tang <xmader@distributive.network>
Co-authored-by: Tom Wenzheng Tang <xmader@distributive.network>
BF-42: UCS4-range strings do not work properly when passed as arguments to JS-defined functions
…-called `global` argument is actually the `this` value to a JS function
https://distributive.atlassian.net/jira/software/c/projects/BF2/issues/BF2-31
This MR implements coercion for python strings to javascript strings, and python functions to javascript functions.