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Split PyProxy method definitions into separate js file (#1368)

This commit is contained in:
Hood Chatham 2021-03-24 10:50:13 -07:00 committed by GitHub
parent f2d6137673
commit d4525a188f
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3 changed files with 580 additions and 552 deletions
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4
docs/usage/api-reference.md
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@ -8,7 +8,3 @@
api/python-api.md
api/micropip-api.md
```

561
src/core/pyproxy.c
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@ -686,554 +686,6 @@ EM_JS_REF(JsRef, pyproxy_new, (PyObject * ptrobj), {
return Module.hiwire.new_value(proxy);
});
// clang-format off
EM_JS_NUM(int, pyproxy_init_js, (), {
Module.PyProxies = {};
function _getPtr(jsobj) {
let ptr = jsobj.$$.ptr;
if (ptr === null) {
throw new Error("Object has already been destroyed");
}
return ptr;
}
let _pyproxyClassMap = new Map();
/**
* Retreive the appropriate mixins based on the features requested in flags.
* Used by pyproxy_new. The "flags" variable is produced by the C function
* pyproxy_getflags. Multiple PyProxies with the same set of feature flags
* will share the same prototype, so the memory footprint of each individual
* PyProxy is minimal.
*/
Module.getPyProxyClass = function(flags){
let result = _pyproxyClassMap.get(flags);
if(result){
return result;
}
let descriptors = {};
for(let [feature_flag, methods] of [
[HAS_LENGTH, Module.PyProxyLengthMethods],
[HAS_GET, Module.PyProxyGetItemMethods],
[HAS_SET, Module.PyProxySetItemMethods],
[HAS_CONTAINS, Module.PyProxyContainsMethods],
[IS_ITERABLE, Module.PyProxyIterableMethods],
[IS_ITERATOR, Module.PyProxyIteratorMethods],
[IS_AWAITABLE, Module.PyProxyAwaitableMethods],
[IS_BUFFER, Module.PyProxyBufferMethods],
[IS_CALLABLE, Module.PyProxyCallableMethods],
]){
if(flags & feature_flag){
Object.assign(descriptors,
Object.getOwnPropertyDescriptors(methods)
);
}
}
let new_proto = Object.create(Module.PyProxyClass.prototype, descriptors);
function PyProxy(){};
PyProxy.prototype = new_proto;
_pyproxyClassMap.set(flags, PyProxy);
return PyProxy;
};
// Static methods
Module.PyProxy = {
_getPtr,
isPyProxy: function(jsobj) {
return jsobj && jsobj.$$ !== undefined && jsobj.$$.type === 'PyProxy';
},
};
Module.callPyObject = function(ptrobj, ...jsargs) {
let idargs = Module.hiwire.new_value(jsargs);
let idresult;
try {
idresult = __pyproxy_apply(ptrobj, idargs);
} catch(e){
Module.fatal_error(e);
} finally {
Module.hiwire.decref(idargs);
}
if(idresult === 0){
_pythonexc2js();
}
return Module.hiwire.pop_value(idresult);
};
// Now a lot of boilerplate to wrap the abstract Object protocol wrappers
// above in Javascript functions.
Module.PyProxyClass = class {
constructor(){
throw new TypeError('PyProxy is not a constructor');
}
get [Symbol.toStringTag] (){
return "PyProxy";
}
get type() {
let ptrobj = _getPtr(this);
return Module.hiwire.pop_value(__pyproxy_type(ptrobj));
}
toString() {
let ptrobj = _getPtr(this);
let jsref_repr;
try {
jsref_repr = __pyproxy_repr(ptrobj);
} catch(e){
Module.fatal_error(e);
}
if(jsref_repr === 0){
_pythonexc2js();
}
return Module.hiwire.pop_value(jsref_repr);
}
destroy() {
let ptrobj = _getPtr(this);
__pyproxy_destroy(ptrobj);
this.$$.ptr = null;
}
/**
* This one doesn't follow the pattern: the inner function
* _python2js_with_depth is defined in python2js.c and is not a Python
* Object Protocol wrapper.
*/
toJs(depth = -1){
let idresult = _python2js_with_depth(_getPtr(this), depth);
let result = Module.hiwire.get_value(idresult);
Module.hiwire.decref(idresult);
return result;
}
apply(jsthis, jsargs) {
return Module.callPyObject(_getPtr(this), ...jsargs);
}
call(jsthis, ...jsargs){
return Module.callPyObject(_getPtr(this), ...jsargs);
}
};
// Controlled by HAS_LENGTH, appears for any object with __len__ or sq_length
// or mp_length methods
Module.PyProxyLengthMethods = {
get length(){
let ptrobj = _getPtr(this);
let length;
try {
length = _PyObject_Size(ptrobj);
} catch(e) {
Module.fatal_error(e);
}
if(length === -1){
_pythonexc2js();
}
return length;
}
};
// Controlled by HAS_GET, appears for any class with __getitem__,
// mp_subscript, or sq_item methods
Module.PyProxyGetItemMethods = {
get : function(key){
let ptrobj = _getPtr(this);
let idkey = Module.hiwire.new_value(key);
let idresult;
try {
idresult = __pyproxy_getitem(ptrobj, idkey);
} catch(e) {
Module.fatal_error(e);
} finally {
Module.hiwire.decref(idkey);
}
if(idresult === 0){
if(Module._PyErr_Occurred()){
_pythonexc2js();
} else {
return undefined;
}
}
return Module.hiwire.pop_value(idresult);
},
};
// Controlled by HAS_SET, appears for any class with __setitem__, __delitem__,
// mp_ass_subscript, or sq_ass_item.
Module.PyProxySetItemMethods = {
set : function(key, value){
let ptrobj = _getPtr(this);
let idkey = Module.hiwire.new_value(key);
let idval = Module.hiwire.new_value(value);
let errcode;
try {
errcode = __pyproxy_setitem(ptrobj, idkey, idval);
} catch(e) {
Module.fatal_error(e);
} finally {
Module.hiwire.decref(idkey);
Module.hiwire.decref(idval);
}
if(errcode === -1){
_pythonexc2js();
}
},
delete : function(key) {
let ptrobj = _getPtr(this);
let idkey = Module.hiwire.new_value(key);
let errcode;
try {
errcode = __pyproxy_delitem(ptrobj, idkey);
} catch(e) {
Module.fatal_error(e);
} finally {
Module.hiwire.decref(idkey);
}
if(errcode === -1){
_pythonexc2js();
}
}
};
// Controlled by HAS_CONTAINS flag, appears for any class with __contains__ or
// sq_contains
Module.PyProxyContainsMethods = {
has : function(key) {
let ptrobj = _getPtr(this);
let idkey = Module.hiwire.new_value(key);
let result;
try {
result = __pyproxy_contains(ptrobj, idkey);
} catch(e) {
Module.fatal_error(e);
} finally {
Module.hiwire.decref(idkey);
}
if(result === -1){
_pythonexc2js();
}
return result === 1;
},
};
// Controlled by IS_ITERABLE, appears for any object with __iter__ or tp_iter, unless
// they are iterators.
// See:
// https://docs.python.org/3/c-api/iter.html
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols
// This avoids allocating a PyProxy wrapper for the temporary iterator.
Module.PyProxyIterableMethods = {
[Symbol.iterator] : function*() {
let iterptr = _PyObject_GetIter(_getPtr(this));
if(iterptr === 0){
pythonexc2js();
}
let item;
while((item = __pyproxy_iter_next(iterptr))){
yield Module.hiwire.pop_value(item);
}
if(_PyErr_Occurred()){
pythonexc2js();
}
_Py_DecRef(iterptr);
}
};
// Controlled by IS_ITERATOR, appears for any object with a __next__ or
// tp_iternext method.
Module.PyProxyIteratorMethods = {
[Symbol.iterator] : function() {
return this;
},
next : function(arg) {
let idresult;
// Note: arg is optional, if arg is not supplied, it will be undefined
// which gets converted to "Py_None". This is as intended.
let idarg = Module.hiwire.new_value(arg);
try {
idresult = __pyproxyGen_Send(_getPtr(this), idarg);
} catch(e) {
Module.fatal_error(e);
} finally {
Module.hiwire.decref(idarg);
}
let done = false;
if(idresult === 0){
idresult = __pyproxyGen_FetchStopIterationValue();
if (idresult){
done = true;
} else {
_pythonexc2js();
}
}
let value = Module.hiwire.pop_value(idresult);
return { done, value };
},
};
// Another layer of boilerplate. The PyProxyHandlers have some annoying logic
// to deal with straining out the spurious "Function" properties "prototype",
// "arguments", and "length", to deal with correctly satisfying the Proxy
// invariants, and to deal with the mro
function python_hasattr(jsobj, jskey){
let ptrobj = _getPtr(jsobj);
let idkey = Module.hiwire.new_value(jskey);
let result;
try {
result = __pyproxy_hasattr(ptrobj, idkey);
} catch(e){
Module.fatal_error(e);
} finally {
Module.hiwire.decref(idkey);
}
if(result === -1){
_pythonexc2js();
}
return result !== 0;
}
// Returns a JsRef in order to allow us to differentiate between "not found"
// (in which case we return 0) and "found 'None'" (in which case we return
// Js_undefined).
function python_getattr(jsobj, jskey){
let ptrobj = _getPtr(jsobj);
let idkey = Module.hiwire.new_value(jskey);
let idresult;
try {
idresult = __pyproxy_getattr(ptrobj, idkey);
} catch(e) {
Module.fatal_error(e);
} finally {
Module.hiwire.decref(idkey);
}
if(idresult === 0){
if(_PyErr_Occurred()){
_pythonexc2js();
}
}
return idresult;
}
function python_setattr(jsobj, jskey, jsval){
let ptrobj = _getPtr(jsobj);
let idkey = Module.hiwire.new_value(jskey);
let idval = Module.hiwire.new_value(jsval);
let errcode;
try {
errcode = __pyproxy_setattr(ptrobj, idkey, idval);
} catch(e) {
Module.fatal_error(e);
} finally {
Module.hiwire.decref(idkey);
Module.hiwire.decref(idval);
}
if(errcode === -1){
_pythonexc2js();
}
}
function python_delattr(jsobj, jskey){
let ptrobj = _getPtr(jsobj);
let idkey = Module.hiwire.new_value(jskey);
let errcode;
try {
errcode = __pyproxy_delattr(ptrobj, idkey);
} catch(e) {
Module.fatal_error(e);
} finally {
Module.hiwire.decref(idkey);
}
if(errcode === -1){
_pythonexc2js();
}
}
// See explanation of which methods should be defined here and what they do here:
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy
Module.PyProxyHandlers = {
isExtensible: function() { return true },
has: function (jsobj, jskey) {
// Note: must report "prototype" in proxy when we are callable.
// (We can return the wrong value from "get" handler though.)
let objHasKey = Reflect.has(jsobj, jskey);
if(objHasKey){
return true;
}
// python_hasattr will crash when given a Symbol.
if(typeof(jskey) === "symbol"){
return false;
}
return python_hasattr(jsobj, jskey);
},
get: function (jsobj, jskey) {
// Preference order:
// 1. things we have to return to avoid making Javascript angry
// 2. the result of Python getattr
// 3. stuff from the prototype chain
// 1. things we have to return to avoid making Javascript angry
// This conditional looks funky but it's the only thing I found that
// worked right in all cases.
if((jskey in jsobj) && !(jskey in Object.getPrototypeOf(jsobj)) ){
return Reflect.get(jsobj, jskey);
}
// python_getattr will crash when given a Symbol
if(typeof(jskey) === "symbol"){
return Reflect.get(jsobj, jskey);
}
// 2. The result of getattr
let idresult = python_getattr(jsobj, jskey);
if(idresult !== 0){
return Module.hiwire.pop_value(idresult);
}
// 3. stuff from the prototype chain.
return Reflect.get(jsobj, jskey);
},
set: function (jsobj, jskey, jsval) {
// We're only willing to set properties on the python object, throw an
// error if user tries to write over any key of type 1. things we have to
// return to avoid making Javascript angry
if(typeof(jskey) === "symbol"){
throw new TypeError(`Cannot set read only field '${jskey.description}'`);
}
// Again this is a funny looking conditional, I found it as the result of
// a lengthy search for something that worked right.
let descr = Object.getOwnPropertyDescriptor(jsobj, jskey);
if(descr && !descr.writable){
throw new TypeError(`Cannot set read only field '${jskey}'`);
}
python_setattr(jsobj, jskey, jsval);
return true;
},
deleteProperty: function (jsobj, jskey) {
// We're only willing to delete properties on the python object, throw an
// error if user tries to write over any key of type 1. things we have to
// return to avoid making Javascript angry
if(typeof(jskey) === "symbol"){
throw new TypeError(`Cannot delete read only field '${jskey.description}'`);
}
let descr = Object.getOwnPropertyDescriptor(jsobj, jskey);
if(descr && !descr.writable){
throw new TypeError(`Cannot delete read only field '${jskey}'`);
}
python_delattr(jsobj, jskey);
// Must return "false" if "jskey" is a nonconfigurable own property.
// Otherwise Javascript will throw a TypeError.
return !descr || descr.configurable;
},
ownKeys: function (jsobj) {
let ptrobj = _getPtr(jsobj);
let idresult;
try {
idresult = __pyproxy_ownKeys(ptrobj);
} catch(e) {
Module.fatal_error(e);
}
let result = Module.hiwire.pop_value(idresult);
result.push(...Reflect.ownKeys(jsobj));
return result;
},
apply: function (jsobj, jsthis, jsargs) {
return jsobj.apply(jsthis, jsargs);
},
};
/**
* The Promise / javascript awaitable API.
*/
Module.PyProxyAwaitableMethods = {
/**
* This wraps __pyproxy_ensure_future and makes a function that converts a
* Python awaitable to a promise, scheduling the awaitable on the Python
* event loop if necessary.
*/
_ensure_future : function(){
let resolve_handle_id = 0;
let reject_handle_id = 0;
let resolveHandle;
let rejectHandle;
let promise;
try {
promise = new Promise((resolve, reject) => {
resolveHandle = resolve;
rejectHandle = reject;
});
resolve_handle_id = Module.hiwire.new_value(resolveHandle);
reject_handle_id = Module.hiwire.new_value(rejectHandle);
let ptrobj = _getPtr(this);
let errcode = __pyproxy_ensure_future(ptrobj, resolve_handle_id, reject_handle_id);
if(errcode === -1){
_pythonexc2js();
}
} finally {
Module.hiwire.decref(resolve_handle_id);
Module.hiwire.decref(reject_handle_id);
}
return promise;
},
then : function(onFulfilled, onRejected){
let promise = this._ensure_future();
return promise.then(onFulfilled, onRejected);
},
catch : function(onRejected){
let promise = this._ensure_future();
return promise.catch(onRejected);
},
finally : function(onFinally){
let promise = this._ensure_future();
return promise.finally(onFinally);
}
};
Module.PyProxyCallableMethods = { prototype : Function.prototype };
Module.PyProxyBufferMethods = {};
// A special proxy that we use to wrap pyodide.globals to allow property access
// like `pyodide.globals.x`.
let globalsPropertyAccessWarned = false;
let globalsPropertyAccessWarningMsg =
"Access to pyodide.globals via pyodide.globals.key is deprecated and " +
"will be removed in version 0.18.0. Use pyodide.globals.get('key'), " +
"pyodide.globals.set('key', value), pyodide.globals.delete('key') instead.";
let NamespaceProxyHandlers = {
has : function(obj, key){
return Reflect.has(obj, key) || obj.has(key);
},
get : function(obj, key){
if(Reflect.has(obj, key)){
return Reflect.get(obj, key);
}
let result = obj.get(key);
if(!globalsPropertyAccessWarned && result !== undefined){
console.warn(globalsPropertyAccessWarningMsg);
globalsPropertyAccessWarned = true;
}
return result;
},
set : function(obj, key, value){
if(Reflect.has(obj, key)){
throw new Error(`Cannot set read only field ${key}`);
}
if(!globalsPropertyAccessWarned){
globalsPropertyAccessWarned = true;
console.warn(globalsPropertyAccessWarningMsg);
}
obj.set(key, value);
},
ownKeys: function (obj) {
let result = new Set(Reflect.ownKeys(obj));
let iter = obj.keys();
for(let key of iter){
result.add(key);
}
iter.destroy();
return Array.from(result);
}
};
Module.wrapNamespace = function wrapNamespace(ns){
return new Proxy(ns, NamespaceProxyHandlers);
};
return 0;
});
// clang-format on
EM_JS_REF(JsRef, create_once_callable, (PyObject * obj), {
@ -1348,6 +800,19 @@ static PyMethodDef pyproxy_methods[] = {
{ NULL } /* Sentinel */
};
// Some special helper macros to hack it so that "pyproxy.js" parses as a
// javascript file for JsDoc. See comment with explanation there.
#define UNPAIRED_OPEN_BRACE {
#define UNPAIRED_CLOSE_BRACE } // Just here to help text editors pair braces up
#define TEMP_EMJS_HELPER(a, args...) \
EM_JS_NUM(int, pyproxy_init_js, (), UNPAIRED_OPEN_BRACE { args return 0; })
#include "pyproxy.js"
#undef TEMP_EMJS_HELPER
#undef UNPAIRED_OPEN_BRACE
#undef UNPAIRED_CLOSE_BRACE
int
pyproxy_init(PyObject* core)
{

567
src/core/pyproxy.js Normal file
View File

@ -0,0 +1,567 @@
// This file to be included from pyproxy.c
//
// The point is to make a file that works with JsDoc. JsDoc will give up if it
// fails to parse the file as javascript. Thus, it's key that this file should
// parse as valid javascript. `TEMP_EMJS_HELPER` is a specially designed macro
// to allow us to do this. We need TEMP_EMJS_HELPER to parse like a javascript
// function call. The easiest way to get it to parse is to make the "argument"
// look like a function call, which we do with `()=>{`. However, `()=>{` is an
// invalid C string so the macro needs to remove it. We put `()=>{0,`,
// TEMP_EMJS_HELPER removes everything up to the comma and replace it with a
// single open brace.
//
// See definition of TEMP_EMJS_HELPER:
// #define TEMP_EMJS_HELPER(a, args...) \
// EM_JS(int, pyproxy_init, (), UNPAIRED_OPEN_BRACE { args return 0; })
// clang-format off
TEMP_EMJS_HELPER(() => {0, /* Magic, see comment */
Module.PyProxies = {};
// clang-format on
function _getPtr(jsobj) {
let ptr = jsobj.$$.ptr;
if (ptr === null) {
throw new Error("Object has already been destroyed");
}
return ptr;
}
let _pyproxyClassMap = new Map();
/**
* Retreive the appropriate mixins based on the features requested in flags.
* Used by pyproxy_new. The "flags" variable is produced by the C function
* pyproxy_getflags. Multiple PyProxies with the same set of feature flags
* will share the same prototype, so the memory footprint of each individual
* PyProxy is minimal.
*/
Module.getPyProxyClass = function(flags) {
let result = _pyproxyClassMap.get(flags);
if (result) {
return result;
}
let descriptors = {};
// clang-format off
for(let [feature_flag, methods] of [
[HAS_LENGTH, Module.PyProxyLengthMethods],
[HAS_GET, Module.PyProxyGetItemMethods],
[HAS_SET, Module.PyProxySetItemMethods],
[HAS_CONTAINS, Module.PyProxyContainsMethods],
[IS_ITERABLE, Module.PyProxyIterableMethods],
[IS_ITERATOR, Module.PyProxyIteratorMethods],
[IS_AWAITABLE, Module.PyProxyAwaitableMethods],
[IS_BUFFER, Module.PyProxyBufferMethods],
[IS_CALLABLE, Module.PyProxyCallableMethods],
]){
// clang-format on
if (flags & feature_flag) {
Object.assign(descriptors, Object.getOwnPropertyDescriptors(methods));
}
}
let new_proto = Object.create(Module.PyProxyClass.prototype, descriptors);
function PyProxy() {};
PyProxy.prototype = new_proto;
_pyproxyClassMap.set(flags, PyProxy);
return PyProxy;
};
// Static methods
Module.PyProxy = {
_getPtr,
isPyProxy : function(jsobj) {
return jsobj && jsobj.$$ !== undefined && jsobj.$$.type === 'PyProxy';
},
};
Module.callPyObject = function(ptrobj, ...jsargs) {
let idargs = Module.hiwire.new_value(jsargs);
let idresult;
try {
idresult = __pyproxy_apply(ptrobj, idargs);
} catch (e) {
Module.fatal_error(e);
} finally {
Module.hiwire.decref(idargs);
}
if (idresult === 0) {
_pythonexc2js();
}
return Module.hiwire.pop_value(idresult);
};
// Now a lot of boilerplate to wrap the abstract Object protocol wrappers
// above in Javascript functions.
Module.PyProxyClass = class {
constructor() { throw new TypeError('PyProxy is not a constructor'); }
get[Symbol.toStringTag]() { return "PyProxy"; }
get type() {
let ptrobj = _getPtr(this);
return Module.hiwire.pop_value(__pyproxy_type(ptrobj));
}
toString() {
let ptrobj = _getPtr(this);
let jsref_repr;
try {
jsref_repr = __pyproxy_repr(ptrobj);
} catch (e) {
Module.fatal_error(e);
}
if (jsref_repr === 0) {
_pythonexc2js();
}
return Module.hiwire.pop_value(jsref_repr);
}
destroy() {
let ptrobj = _getPtr(this);
__pyproxy_destroy(ptrobj);
this.$$.ptr = null;
}
/**
* This one doesn't follow the pattern: the inner function
* _python2js_with_depth is defined in python2js.c and is not a Python
* Object Protocol wrapper.
*/
toJs(depth = -1) {
let idresult = _python2js_with_depth(_getPtr(this), depth);
let result = Module.hiwire.get_value(idresult);
Module.hiwire.decref(idresult);
return result;
}
apply(jsthis, jsargs) {
return Module.callPyObject(_getPtr(this), ...jsargs);
}
call(jsthis, ...jsargs) {
return Module.callPyObject(_getPtr(this), ...jsargs);
}
};
// Controlled by HAS_LENGTH, appears for any object with __len__ or sq_length
// or mp_length methods
Module.PyProxyLengthMethods = {
get length() {
let ptrobj = _getPtr(this);
let length;
try {
length = _PyObject_Size(ptrobj);
} catch (e) {
Module.fatal_error(e);
}
if (length === -1) {
_pythonexc2js();
}
return length;
}
};
// Controlled by HAS_GET, appears for any class with __getitem__,
// mp_subscript, or sq_item methods
Module.PyProxyGetItemMethods = {
get : function(key) {
let ptrobj = _getPtr(this);
let idkey = Module.hiwire.new_value(key);
let idresult;
try {
idresult = __pyproxy_getitem(ptrobj, idkey);
} catch (e) {
Module.fatal_error(e);
} finally {
Module.hiwire.decref(idkey);
}
if (idresult === 0) {
if (Module._PyErr_Occurred()) {
_pythonexc2js();
} else {
return undefined;
}
}
return Module.hiwire.pop_value(idresult);
},
};
// Controlled by HAS_SET, appears for any class with __setitem__, __delitem__,
// mp_ass_subscript, or sq_ass_item.
Module.PyProxySetItemMethods = {
set : function(key, value) {
let ptrobj = _getPtr(this);
let idkey = Module.hiwire.new_value(key);
let idval = Module.hiwire.new_value(value);
let errcode;
try {
errcode = __pyproxy_setitem(ptrobj, idkey, idval);
} catch (e) {
Module.fatal_error(e);
} finally {
Module.hiwire.decref(idkey);
Module.hiwire.decref(idval);
}
if (errcode === -1) {
_pythonexc2js();
}
},
delete : function(key) {
let ptrobj = _getPtr(this);
let idkey = Module.hiwire.new_value(key);
let errcode;
try {
errcode = __pyproxy_delitem(ptrobj, idkey);
} catch (e) {
Module.fatal_error(e);
} finally {
Module.hiwire.decref(idkey);
}
if (errcode === -1) {
_pythonexc2js();
}
}
};
// Controlled by HAS_CONTAINS flag, appears for any class with __contains__ or
// sq_contains
Module.PyProxyContainsMethods = {
has : function(key) {
let ptrobj = _getPtr(this);
let idkey = Module.hiwire.new_value(key);
let result;
try {
result = __pyproxy_contains(ptrobj, idkey);
} catch (e) {
Module.fatal_error(e);
} finally {
Module.hiwire.decref(idkey);
}
if (result === -1) {
_pythonexc2js();
}
return result === 1;
},
};
// Controlled by IS_ITERABLE, appears for any object with __iter__ or tp_iter,
// unless they are iterators. See: https://docs.python.org/3/c-api/iter.html
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols
// This avoids allocating a PyProxy wrapper for the temporary iterator.
Module.PyProxyIterableMethods = {
[Symbol.iterator] : function*() {
let iterptr = _PyObject_GetIter(_getPtr(this));
if (iterptr === 0) {
pythonexc2js();
}
let item;
while ((item = __pyproxy_iter_next(iterptr))) {
yield Module.hiwire.pop_value(item);
}
if (_PyErr_Occurred()) {
pythonexc2js();
}
_Py_DecRef(iterptr);
}
};
// Controlled by IS_ITERATOR, appears for any object with a __next__ or
// tp_iternext method.
Module.PyProxyIteratorMethods = {
[Symbol.iterator] : function() { return this; },
next : function(arg) {
let idresult;
// Note: arg is optional, if arg is not supplied, it will be undefined
// which gets converted to "Py_None". This is as intended.
let idarg = Module.hiwire.new_value(arg);
try {
idresult = __pyproxyGen_Send(_getPtr(this), idarg);
} catch (e) {
Module.fatal_error(e);
} finally {
Module.hiwire.decref(idarg);
}
let done = false;
if (idresult === 0) {
idresult = __pyproxyGen_FetchStopIterationValue();
if (idresult) {
done = true;
} else {
_pythonexc2js();
}
}
let value = Module.hiwire.pop_value(idresult);
return {done, value};
},
};
// Another layer of boilerplate. The PyProxyHandlers have some annoying logic
// to deal with straining out the spurious "Function" properties "prototype",
// "arguments", and "length", to deal with correctly satisfying the Proxy
// invariants, and to deal with the mro
function python_hasattr(jsobj, jskey) {
let ptrobj = _getPtr(jsobj);
let idkey = Module.hiwire.new_value(jskey);
let result;
try {
result = __pyproxy_hasattr(ptrobj, idkey);
} catch (e) {
Module.fatal_error(e);
} finally {
Module.hiwire.decref(idkey);
}
if (result === -1) {
_pythonexc2js();
}
return result !== 0;
}
// Returns a JsRef in order to allow us to differentiate between "not found"
// (in which case we return 0) and "found 'None'" (in which case we return
// Js_undefined).
function python_getattr(jsobj, jskey) {
let ptrobj = _getPtr(jsobj);
let idkey = Module.hiwire.new_value(jskey);
let idresult;
try {
idresult = __pyproxy_getattr(ptrobj, idkey);
} catch (e) {
Module.fatal_error(e);
} finally {
Module.hiwire.decref(idkey);
}
if (idresult === 0) {
if (_PyErr_Occurred()) {
_pythonexc2js();
}
}
return idresult;
}
function python_setattr(jsobj, jskey, jsval) {
let ptrobj = _getPtr(jsobj);
let idkey = Module.hiwire.new_value(jskey);
let idval = Module.hiwire.new_value(jsval);
let errcode;
try {
errcode = __pyproxy_setattr(ptrobj, idkey, idval);
} catch (e) {
Module.fatal_error(e);
} finally {
Module.hiwire.decref(idkey);
Module.hiwire.decref(idval);
}
if (errcode === -1) {
_pythonexc2js();
}
}
function python_delattr(jsobj, jskey) {
let ptrobj = _getPtr(jsobj);
let idkey = Module.hiwire.new_value(jskey);
let errcode;
try {
errcode = __pyproxy_delattr(ptrobj, idkey);
} catch (e) {
Module.fatal_error(e);
} finally {
Module.hiwire.decref(idkey);
}
if (errcode === -1) {
_pythonexc2js();
}
}
// See explanation of which methods should be defined here and what they do
// here:
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy
Module.PyProxyHandlers = {
isExtensible : function() { return true },
has : function(jsobj, jskey) {
// Note: must report "prototype" in proxy when we are callable.
// (We can return the wrong value from "get" handler though.)
let objHasKey = Reflect.has(jsobj, jskey);
if (objHasKey) {
return true;
}
// python_hasattr will crash when given a Symbol.
if (typeof (jskey) === "symbol") {
return false;
}
return python_hasattr(jsobj, jskey);
},
get : function(jsobj, jskey) {
// Preference order:
// 1. things we have to return to avoid making Javascript angry
// 2. the result of Python getattr
// 3. stuff from the prototype chain
// 1. things we have to return to avoid making Javascript angry
// This conditional looks funky but it's the only thing I found that
// worked right in all cases.
if ((jskey in jsobj) && !(jskey in Object.getPrototypeOf(jsobj))) {
return Reflect.get(jsobj, jskey);
}
// python_getattr will crash when given a Symbol
if (typeof (jskey) === "symbol") {
return Reflect.get(jsobj, jskey);
}
// 2. The result of getattr
let idresult = python_getattr(jsobj, jskey);
if (idresult !== 0) {
return Module.hiwire.pop_value(idresult);
}
// 3. stuff from the prototype chain.
return Reflect.get(jsobj, jskey);
},
set : function(jsobj, jskey, jsval) {
// We're only willing to set properties on the python object, throw an
// error if user tries to write over any key of type 1. things we have to
// return to avoid making Javascript angry
if (typeof (jskey) === "symbol") {
throw new TypeError(
`Cannot set read only field '${jskey.description}'`);
}
// Again this is a funny looking conditional, I found it as the result of
// a lengthy search for something that worked right.
let descr = Object.getOwnPropertyDescriptor(jsobj, jskey);
if (descr && !descr.writable) {
throw new TypeError(`Cannot set read only field '${jskey}'`);
}
python_setattr(jsobj, jskey, jsval);
return true;
},
deleteProperty : function(jsobj, jskey) {
// We're only willing to delete properties on the python object, throw an
// error if user tries to write over any key of type 1. things we have to
// return to avoid making Javascript angry
if (typeof (jskey) === "symbol") {
throw new TypeError(
`Cannot delete read only field '${jskey.description}'`);
}
let descr = Object.getOwnPropertyDescriptor(jsobj, jskey);
if (descr && !descr.writable) {
throw new TypeError(`Cannot delete read only field '${jskey}'`);
}
python_delattr(jsobj, jskey);
// Must return "false" if "jskey" is a nonconfigurable own property.
// Otherwise Javascript will throw a TypeError.
return !descr || descr.configurable;
},
ownKeys : function(jsobj) {
let ptrobj = _getPtr(jsobj);
let idresult;
try {
idresult = __pyproxy_ownKeys(ptrobj);
} catch (e) {
Module.fatal_error(e);
}
let result = Module.hiwire.pop_value(idresult);
result.push(...Reflect.ownKeys(jsobj));
return result;
},
// clang-format off
apply : function(jsobj, jsthis, jsargs) {
return jsobj.apply(jsthis, jsargs);
},
// clang-format on
};
/**
* The Promise / javascript awaitable API.
*/
Module.PyProxyAwaitableMethods = {
/**
* This wraps __pyproxy_ensure_future and makes a function that converts a
* Python awaitable to a promise, scheduling the awaitable on the Python
* event loop if necessary.
*/
_ensure_future : function() {
let resolve_handle_id = 0;
let reject_handle_id = 0;
let resolveHandle;
let rejectHandle;
let promise;
try {
promise = new Promise((resolve, reject) => {
resolveHandle = resolve;
rejectHandle = reject;
});
resolve_handle_id = Module.hiwire.new_value(resolveHandle);
reject_handle_id = Module.hiwire.new_value(rejectHandle);
let ptrobj = _getPtr(this);
let errcode = __pyproxy_ensure_future(ptrobj, resolve_handle_id,
reject_handle_id);
if (errcode === -1) {
_pythonexc2js();
}
} finally {
Module.hiwire.decref(resolve_handle_id);
Module.hiwire.decref(reject_handle_id);
}
return promise;
},
then : function(onFulfilled, onRejected) {
let promise = this._ensure_future();
return promise.then(onFulfilled, onRejected);
},
catch : function(onRejected) {
let promise = this._ensure_future();
return promise.catch(onRejected);
},
finally : function(onFinally) {
let promise = this._ensure_future();
return promise.finally(onFinally);
}
};
Module.PyProxyCallableMethods = {prototype : Function.prototype};
Module.PyProxyBufferMethods = {};
// A special proxy that we use to wrap pyodide.globals to allow property
// access like `pyodide.globals.x`.
let globalsPropertyAccessWarned = false;
let globalsPropertyAccessWarningMsg =
"Access to pyodide.globals via pyodide.globals.key is deprecated and " +
"will be removed in version 0.18.0. Use pyodide.globals.get('key'), " +
"pyodide.globals.set('key', value), pyodide.globals.delete('key') instead.";
let NamespaceProxyHandlers = {
// clang-format off
has : function(obj, key) {
return Reflect.has(obj, key) || obj.has(key);
},
// clang-format on
get : function(obj, key) {
if (Reflect.has(obj, key)) {
return Reflect.get(obj, key);
}
let result = obj.get(key);
if (!globalsPropertyAccessWarned && result !== undefined) {
console.warn(globalsPropertyAccessWarningMsg);
globalsPropertyAccessWarned = true;
}
return result;
},
set : function(obj, key, value) {
if (Reflect.has(obj, key)) {
throw new Error(`Cannot set read only field ${key}`);
}
if (!globalsPropertyAccessWarned) {
globalsPropertyAccessWarned = true;
console.warn(globalsPropertyAccessWarningMsg);
}
obj.set(key, value);
},
ownKeys : function(obj) {
let result = new Set(Reflect.ownKeys(obj));
let iter = obj.keys();
for (let key of iter) {
result.add(key);
}
iter.destroy();
return Array.from(result);
}
};
// clang-format off
Module.wrapNamespace = function wrapNamespace(ns) {
return new Proxy(ns, NamespaceProxyHandlers);
};
// clang-format on
return 0;
});