Add 'from js import X' on Python side

Makefile

@@ -22,7 +22,7 @@ LDFLAGS=$(OPTFLAGS) \
 all: build/pyodide.asm.html build/pyodide.js
 
 
-build/pyodide.asm.html: src/main.bc src/jsproxy.bc src/js2python.bc src/pylocals.bc \
+build/pyodide.asm.html: src/main.bc src/jsimport.bc src/jsproxy.bc src/js2python.bc \
                         src/pyproxy.bc src/python2js.bc src/runpython.bc root
 	$(CC) -s EXPORT_NAME="'pyodide'" --bind -o $@ $(filter %.bc,$^) $(LDFLAGS) \
 		$(foreach d,$(wildcard root/*),--preload-file $d@/$(notdir $d))

src/jsimport.cpp

@@ -0,0 +1,104 @@
+#include "jsimport.hpp"
+
+#include "js2python.hpp"
+
+using emscripten::val;
+
+static PyObject *original__import__;
+PyObject *globals = NULL;
+PyObject *original_globals = NULL;
+
+typedef struct {
+  PyObject_HEAD
+} JsImport;
+
+static PyObject *JsImport_Call(PyObject *self, PyObject *args, PyObject *kwargs) {
+  PyObject *name = PyTuple_GET_ITEM(args, 0);
+  if (PyUnicode_CompareWithASCIIString(name, "js") == 0) {
+    PyObject *locals = PyTuple_GET_ITEM(args, 2);
+    PyObject *fromlist = PyTuple_GET_ITEM(args, 3);
+    Py_ssize_t n = PySequence_Size(fromlist);
+    PyObject *jsmod = PyModule_New("js");
+    PyObject *d = PyModule_GetDict(jsmod);
+    for (Py_ssize_t i = 0; i < n; ++i) {
+      PyObject *key = PySequence_GetItem(fromlist, i);
+      if (key == NULL) {
+        return NULL;
+      }
+      char *c = PyUnicode_AsUTF8(key);
+      if (c == NULL) {
+        Py_DECREF(key);
+        return NULL;
+      }
+
+      val jsval = val::global(c);
+      PyObject *pyval = jsToPython(jsval);
+      if (PyDict_SetItem(d, key, pyval)) {
+        Py_DECREF(key);
+        Py_DECREF(pyval);
+        return NULL;
+      }
+      Py_DECREF(key);
+      Py_DECREF(pyval);
+    }
+
+    return jsmod;
+  } else {
+    return PyObject_Call(original__import__, args, kwargs);
+  }
+}
+
+static PyTypeObject JsImportType = {
+  .tp_name = "JsImport",
+  .tp_basicsize = sizeof(JsImport),
+  .tp_flags = Py_TPFLAGS_DEFAULT,
+  .tp_call = JsImport_Call,
+  .tp_doc = "An import hook that imports things from Javascript."
+};
+
+static PyObject *JsImport_New() {
+  JsImport *self;
+  self = (JsImport *)JsImportType.tp_alloc(&JsImportType, 0);
+  return (PyObject *)self;
+}
+
+int JsImport_Ready() {
+  if (PyType_Ready(&JsImportType)) {
+    return 1;
+  }
+
+  PyObject *m = PyImport_AddModule("builtins");
+  if (m == NULL) {
+    return 1;
+  }
+  PyObject *d = PyModule_GetDict(m);
+  if (d == NULL) {
+    return 1;
+  }
+  original__import__ = PyDict_GetItemString(d, "__import__");
+  if (original__import__ == NULL) {
+    return 1;
+  }
+  Py_INCREF(original__import__);
+
+  PyObject *importer = JsImport_New();
+  if (importer == NULL) {
+    return 1;
+  }
+
+  if (PyDict_SetItemString(d, "__import__", importer)) {
+    return 1;
+  }
+
+  m = PyImport_AddModule("__main__");
+  if (m == NULL)
+    return 1;
+  globals = PyModule_GetDict(m);
+
+  m = PyImport_AddModule("builtins");
+  PyDict_Update(globals, PyModule_GetDict(m));
+
+  original_globals = PyDict_Copy(globals);
+
+  return 0;
+}

src/jsimport.hpp

@@ -0,0 +1,10 @@
+#ifndef JSIMPORT_H
+#define JSIMPORT_H
+
+#include <Python.h>
+
+int JsImport_Ready();
+extern PyObject *globals;
+extern PyObject *original_globals;
+
+#endif /* JSIMPORT_H */

src/main.cpp

@@ -4,9 +4,9 @@
 #include <Python.h>
 #include <node.h>  // from CPython
 
+#include "jsimport.hpp"
 #include "jsproxy.hpp"
 #include "js2python.hpp"
-#include "pylocals.hpp"
 #include "pyproxy.hpp"
 #include "python2js.hpp"
 #include "runpython.hpp"
@@ -39,7 +39,7 @@ extern "C" {
     if (JsProxy_Ready() ||
         jsToPython_Ready() ||
         pythonToJs_Ready() ||
-        PyLocals_Ready()) {
+        JsImport_Ready()) {
       return 1;
     }
 

src/pylocals.cpp

@@ -1,123 +0,0 @@
-#include "pylocals.hpp"
-#include "js2python.hpp"
-
-#include <emscripten.h>
-#include <emscripten/bind.h>
-#include <emscripten/val.h>
-
-using emscripten::val;
-
-////////////////////////////////////////////////////////////
-// PyLocals
-//
-// This is an object designed to be used as a "locals" namespace dictionary.
-// It first looks for things in its own internal dictionary, and failing that,
-// looks in the Javascript global namespace.  This is a way of merging the
-// Python and Javascript namespaces without fullying copying either one.
-
-PyObject *locals = NULL;
-PyObject *globals = NULL;
-PyObject *original_globals = NULL;
-
-typedef struct {
-  PyObject_HEAD
-  PyObject *locals;
-} PyLocals;
-
-static void PyLocals_dealloc(PyLocals *self) {
-  Py_DECREF(self->locals);
-  Py_TYPE(self)->tp_free((PyObject *)self);
-}
-
-static Py_ssize_t PyLocals_length(PyObject *o) {
-  PyLocals *self = (PyLocals *)o;
-
-  return PyDict_Size(self->locals);
-}
-
-PyObject* PyLocals_get(PyObject *o, PyObject *key) {
-  PyLocals *self = (PyLocals *)o;
-
-  {
-    PyObject *str = PyObject_Str(key);
-    if (str == NULL) {
-      return NULL;
-    }
-    char *c = PyUnicode_AsUTF8(str);
-    Py_DECREF(str);
-  }
-
-  PyObject *py_val = PyDict_GetItem(self->locals, key);
-  if (py_val != NULL) {
-    Py_INCREF(py_val);
-    return py_val;
-  }
-
-  PyObject *str = PyObject_Str(key);
-  if (str == NULL) {
-    return NULL;
-  }
-  char *c = PyUnicode_AsUTF8(str);
-  val v = val::global(c);
-  Py_DECREF(str);
-  return jsToPython(v);
-}
-
-int PyLocals_set(PyObject *o, PyObject *k, PyObject *v) {
-  PyLocals *self = (PyLocals *)o;
-
-  if (v == NULL) {
-    // TODO: This might not actually be here to delete...
-    return PyDict_DelItem(self->locals, k);
-  } else {
-    return PyDict_SetItem(self->locals, k, v);
-  }
-}
-
-static PyMappingMethods PyLocals_as_mapping = {
-  PyLocals_length,
-  PyLocals_get,
-  PyLocals_set
-};
-
-static PyTypeObject PyLocalsType = {
-  .tp_name = "PyLocals",
-  .tp_basicsize = sizeof(PyLocals),
-  .tp_dealloc = (destructor)PyLocals_dealloc,
-  .tp_as_mapping = &PyLocals_as_mapping,
-  .tp_flags = Py_TPFLAGS_DEFAULT,
-  .tp_doc = "A proxy that looks in a dict first, otherwise in the global JS namespace"
-};
-
-static PyObject *PyLocals_cnew(PyObject *d)
-{
-  PyLocals *self;
-  self = (PyLocals *)PyLocalsType.tp_alloc(&PyLocalsType, 0);
-  if (self != NULL) {
-    Py_INCREF(d);
-    self->locals = d;
-  }
-
-  return (PyObject *)self;
-}
-
-int PyLocals_Ready() {
-  if (PyType_Ready(&PyLocalsType) < 0)
-    return 1;
-
-  PyObject *m = PyImport_AddModule("__main__");
-  if (m == NULL)
-    return 1;
-  globals = PyModule_GetDict(m);
-
-  m = PyImport_AddModule("builtins");
-  PyDict_Update(globals, PyModule_GetDict(m));
-
-  original_globals = PyDict_Copy(globals);
-
-  locals = PyLocals_cnew(globals);
-  if (locals == NULL)
-    return 1;
-
-  return 0;
-}

src/pylocals.hpp

@@ -1,12 +0,0 @@
-#ifndef PYLOCALS_H
-#define PYLOCALS_H
-
-#include <Python.h>
-
-int PyLocals_Ready();
-
-extern PyObject *locals;
-extern PyObject *globals;
-extern PyObject *original_globals;
-
-#endif /* PYLOCALS_H */

src/runpython.cpp

@@ -6,7 +6,7 @@
 #include <Python.h>
 #include <node.h> // from Python
 
-#include "pylocals.hpp"
+#include "jsimport.hpp"
 #include "python2js.hpp"
 
 using emscripten::val;
@@ -57,7 +57,7 @@ val runPython(std::wstring code) {
       *last_line = 0;
       last_line++;
     }
-    ret = PyRun_StringFlags(&*code_utf8.begin(), Py_file_input, globals, locals, &cf);
+    ret = PyRun_StringFlags(&*code_utf8.begin(), Py_file_input, globals, globals, &cf);
     if (ret == NULL) {
       return pythonExcToJs();
     }
@@ -70,10 +70,10 @@ val runPython(std::wstring code) {
     ret = Py_None;
     break;
   case 1:
-    ret = PyRun_StringFlags(&*last_line, Py_eval_input, globals, locals, &cf);
+    ret = PyRun_StringFlags(&*last_line, Py_eval_input, globals, globals, &cf);
     break;
   case 2:
-    ret = PyRun_StringFlags(&*last_line, Py_file_input, globals, locals, &cf);
+    ret = PyRun_StringFlags(&*last_line, Py_file_input, globals, globals, &cf);
     break;
   }
 
@@ -81,19 +81,6 @@ val runPython(std::wstring code) {
     return pythonExcToJs();
   }
 
-  // Now copy all the variables over to the Javascript side
-  {
-    val js_globals = val::global("window");
-    PyObject *k, *v;
-    Py_ssize_t pos = 0;
-
-    while (PyDict_Next(globals, &pos, &k, &v)) {
-      if (!PyDict_Contains(original_globals, k)) {
-        js_globals.set(pythonToJs(k), pythonToJs(v));
-      }
-    }
-  }
-
   val result = pythonToJs(ret);
   Py_DECREF(ret);
   return result;