Properly handle Numpy scalar types in python2js

src/python2js.c

@@ -2,6 +2,9 @@
 
 #include <emscripten.h>
 
+#include <endian.h>
+#include <stdint.h>
+
 #include "hiwire.h"
 #include "jsproxy.h"
 #include "pyproxy.h"
@@ -90,25 +93,6 @@ exit:
   return HW_ERROR;
 }
 
-static int
-is_type_name(PyObject* x, const char* name)
-{
-  PyObject* x_type = PyObject_Type(x);
-  if (x_type == NULL) {
-    // If we can't get a type, that's probably ok in this case...
-    PyErr_Clear();
-    return 0;
-  }
-
-  PyObject* x_type_name = PyObject_Repr(x_type);
-  Py_DECREF(x_type);
-
-  int result = (PyUnicode_CompareWithASCIIString(x_type_name, name) == 0);
-
-  Py_DECREF(x_type_name);
-  return result;
-}
-
 int
 _python2js_add_to_cache(PyObject* map, PyObject* pyparent, int jsparent);
 
@@ -250,6 +234,315 @@ _python2js_dict(PyObject* x, PyObject* map)
   return jsdict;
 }
 
+typedef int(scalar_converter)(char*);
+
+static int
+_convert_bool(char* data)
+{
+  char v = *((char*)data);
+  if (v) {
+    return hiwire_true();
+  } else {
+    return hiwire_false();
+  }
+}
+
+static int
+_convert_int8(char* data)
+{
+  int8_t v = *((int8_t*)data);
+  return hiwire_int(v);
+}
+
+static int
+_convert_uint8(char* data)
+{
+  uint8_t v = *((uint8_t*)data);
+  return hiwire_int(v);
+}
+
+static int
+_convert_int16(char* data)
+{
+  int16_t v = *((int16_t*)data);
+  return hiwire_int(v);
+}
+
+static int
+_convert_int16_swap(char* data)
+{
+  int16_t v = *((int16_t*)data);
+  return hiwire_int(be16toh(v));
+}
+
+static int
+_convert_uint16(char* data)
+{
+  uint16_t v = *((uint16_t*)data);
+  return hiwire_int(v);
+}
+
+static int
+_convert_uint16_swap(char* data)
+{
+  uint16_t v = *((uint16_t*)data);
+  return hiwire_int(be16toh(v));
+}
+
+static int
+_convert_int32(char* data)
+{
+  int32_t v = *((int32_t*)data);
+  return hiwire_int(v);
+}
+
+static int
+_convert_int32_swap(char* data)
+{
+  int32_t v = *((int32_t*)data);
+  return hiwire_int(be32toh(v));
+}
+
+static int
+_convert_uint32(char* data)
+{
+  uint32_t v = *((uint32_t*)data);
+  return hiwire_int(v);
+}
+
+static int
+_convert_uint32_swap(char* data)
+{
+  uint32_t v = *((uint32_t*)data);
+  return hiwire_int(be32toh(v));
+}
+
+static int
+_convert_int64(char* data)
+{
+  int64_t v = *((int64_t*)data);
+  return hiwire_int(v);
+}
+
+static int
+_convert_int64_swap(char* data)
+{
+  int64_t v = *((int64_t*)data);
+  return hiwire_int(be64toh(v));
+}
+
+static int
+_convert_uint64(char* data)
+{
+  uint64_t v = *((uint64_t*)data);
+  return hiwire_int(v);
+}
+
+static int
+_convert_uint64_swap(char* data)
+{
+  uint64_t v = *((uint64_t*)data);
+  return hiwire_int(be64toh(v));
+}
+
+static int
+_convert_float32(char* data)
+{
+  float v = *((float*)data);
+  return hiwire_double(v);
+}
+
+static int
+_convert_float32_swap(char* data)
+{
+  union float32_t
+  {
+    uint32_t i;
+    float f;
+  } v;
+
+  v.f = *((float*)data);
+  v.i = be32toh(v.i);
+  return hiwire_double(v.f);
+}
+
+static int
+_convert_float64(char* data)
+{
+  double v = *((double*)data);
+  return hiwire_double(v);
+}
+
+static int
+_convert_float64_swap(char* data)
+{
+  union float64_t
+  {
+    uint64_t i;
+    double f;
+  } v;
+
+  v.f = *((double*)data);
+  v.i = be64toh(v.i);
+  return hiwire_double(v.f);
+}
+
+static scalar_converter*
+_python2js_buffer_get_converter(Py_buffer* buff)
+{
+  // Uses Python's struct typecodes as defined here:
+  // https://docs.python.org/3.7/library/array.html
+
+  char format;
+  char swap;
+  if (buff->format == NULL) {
+    swap = 0;
+    format = 'B';
+  } else {
+    switch (buff->format[0]) {
+      case '>':
+      case '!':
+        swap = 1;
+        format = buff->format[1];
+        break;
+      case '=':
+      case '<':
+      case '@':
+        swap = 0;
+        format = buff->format[1];
+        break;
+      default:
+        swap = 0;
+        format = buff->format[0];
+    }
+  }
+
+  switch (format) {
+    case 'c':
+    case 'b':
+      return _convert_int8;
+    case 'B':
+      return _convert_uint8;
+    case '?':
+      return _convert_bool;
+    case 'h':
+      if (swap) {
+        return _convert_int16_swap;
+      } else {
+        return _convert_int16;
+      }
+    case 'H':
+      if (swap) {
+        return _convert_uint16_swap;
+      } else {
+        return _convert_uint16;
+      }
+    case 'i':
+    case 'l':
+    case 'n':
+      if (swap) {
+        return _convert_int32_swap;
+      } else {
+        return _convert_int32;
+      }
+    case 'I':
+    case 'L':
+    case 'N':
+      if (swap) {
+        return _convert_uint32_swap;
+      } else {
+        return _convert_uint32;
+      }
+    case 'q':
+      if (swap) {
+        return _convert_int64_swap;
+      } else {
+        return _convert_int64;
+      }
+    case 'Q':
+      if (swap) {
+        return _convert_uint64_swap;
+      } else {
+        return _convert_uint64;
+      }
+    case 'f':
+      if (swap) {
+        return _convert_float32_swap;
+      } else {
+        return _convert_float32;
+      }
+    case 'd':
+      if (swap) {
+        return _convert_float64_swap;
+      } else {
+        return _convert_float64;
+      }
+    default:
+      return NULL;
+  }
+}
+
+static int
+_python2js_buffer_recursive(Py_buffer* buff,
+                            char* ptr,
+                            int dim,
+                            scalar_converter* convert)
+{
+  // This function is basically a manual conversion of `recursive_tolist` in
+  // Numpy to use the Python buffer interface and output Javascript.
+
+  Py_ssize_t i, n, stride;
+  int jsarray, jsitem;
+
+  if (dim >= buff->ndim) {
+    return convert(ptr);
+  }
+
+  n = buff->shape[dim];
+  stride = buff->strides[dim];
+
+  jsarray = hiwire_array();
+
+  for (i = 0; i < n; ++i) {
+    jsitem = _python2js_buffer_recursive(buff, ptr, dim + 1, convert);
+    if (jsitem == HW_ERROR) {
+      hiwire_decref(jsarray);
+      return HW_ERROR;
+    }
+    hiwire_push_array(jsarray, jsitem);
+    hiwire_decref(jsitem);
+
+    ptr += stride;
+  }
+
+  return jsarray;
+}
+
+static int
+_python2js_buffer(PyObject* x)
+{
+  PyObject* memoryview = PyMemoryView_FromObject(x);
+  if (memoryview == NULL) {
+    PyErr_Clear();
+    return HW_ERROR;
+  }
+
+  Py_buffer* buff;
+  buff = PyMemoryView_GET_BUFFER(memoryview);
+
+  scalar_converter* convert = _python2js_buffer_get_converter(buff);
+  if (convert == NULL) {
+    Py_DECREF(memoryview);
+    return HW_ERROR;
+  }
+
+  int result = _python2js_buffer_recursive(buff, buff->buf, 0, convert);
+
+  Py_DECREF(memoryview);
+
+  return result;
+}
+
 static int
 _python2js(PyObject* x, PyObject* map)
 {
@@ -269,12 +562,18 @@ _python2js(PyObject* x, PyObject* map)
     return _python2js_bytes(x);
   } else if (JsProxy_Check(x)) {
     return JsProxy_AsJs(x);
-  } else if (PyList_Check(x) || PyTuple_Check(x) ||
-             is_type_name(x, "<class 'numpy.ndarray'>")) {
+  } else if (PyList_Check(x) || PyTuple_Check(x)) {
     return _python2js_sequence(x, map);
   } else if (PyDict_Check(x)) {
     return _python2js_dict(x, map);
   } else {
+    int jsbuff = _python2js_buffer(x);
+    if (jsbuff != HW_ERROR) {
+      return jsbuff;
+    }
+    if (PySequence_Check(x)) {
+      return _python2js_sequence(x, map);
+    }
     Py_INCREF(x);
     return pyproxy_new((int)x);
   }

test/test_python.py

@@ -67,6 +67,52 @@ def test_python2js_long_ints(selenium):
     assert selenium.run('-2**31') == -2**31
 
 
+def test_python2js_numpy_dtype(selenium_standalone):
+    selenium = selenium_standalone
+
+    selenium.load_package('numpy')
+    selenium.run("import numpy as np")
+
+    expected_result = [[[0, 1], [2, 3]],
+                       [[4, 5], [6, 7]]]
+
+    for order in ('C', 'F'):
+        for dtype in (
+                'int8',
+                'uint8',
+                'int16',
+                'uint16',
+                'int32',
+                'uint32',
+                'int64',
+                'uint64',
+                'float32',
+                'float64'
+        ):
+            assert selenium.run(
+                f"""
+                x = np.arange(8, dtype=np.{dtype})
+                x = x.reshape((2, 2, 2))
+                x = x.copy({order!r})
+                x
+                """
+            ) == expected_result
+            assert selenium.run(
+                """
+                x.byteswap().newbyteorder()
+                """
+            ) == expected_result
+
+    assert selenium.run("np.array([True, False])") == [True, False]
+
+    selenium.run(
+        "x = np.array([['string1', 'string2'], ['string3', 'string4']])"
+    )
+    assert selenium.run_js("return pyodide.pyimport('x').length") == 2
+    assert selenium.run_js("return pyodide.pyimport('x')[0][0]") == 'string1'
+    assert selenium.run_js("return pyodide.pyimport('x')[1][1]") == 'string4'
+
+
 def test_pythonexc2js(selenium):
     try:
         selenium.run_js('return pyodide.runPython("5 / 0")')