ENH: Support arbitrary-length Python ints in QuadPrecision constructor

quaddtype/numpy_quaddtype/src/scalar.c

@@ -41,6 +41,52 @@ QuadPrecision_raw_new(QuadBackendType backend)
     return new;
 }
 
+static QuadPrecisionObject *
+quad_from_py_int(PyObject *py_int, QuadBackendType backend, QuadPrecisionObject *self_to_cleanup)
+{
+    int overflow = 0;
+    long long lval = PyLong_AsLongLongAndOverflow(py_int, &overflow);
+
+    if (overflow != 0) {
+        // Integer is too large, convert to string and recursively call QuadPrecision_from_object
+        PyObject *str_obj = PyObject_Str(py_int);
+        if (str_obj == NULL) {
+            if (self_to_cleanup) {
+                Py_DECREF(self_to_cleanup);
+            }
+            return NULL;
+        }
+
+        QuadPrecisionObject *result = QuadPrecision_from_object(str_obj, backend);
+        Py_DECREF(str_obj);
+        if (self_to_cleanup) {
+            Py_DECREF(self_to_cleanup);  // discard the default one
+        }
+        return result;
+    }
+    else if (lval == -1 && PyErr_Occurred()) {
+        if (self_to_cleanup) {
+            Py_DECREF(self_to_cleanup);
+        }
+        return NULL;
+    }
+
+    // No overflow, use the integer value directly
+    QuadPrecisionObject *self = self_to_cleanup ? self_to_cleanup : QuadPrecision_raw_new(backend);
+    if (!self) {
+        return NULL;
+    }
+
+    if (backend == BACKEND_SLEEF) {
+        self->value.sleef_value = Sleef_cast_from_int64q1(lval);
+    }
+    else {
+        self->value.longdouble_value = (long double)lval;
+    }
+    return self;
+
+}
+
 QuadPrecisionObject *
 QuadPrecision_from_object(PyObject *value, QuadBackendType backend)
 {   
@@ -76,16 +122,10 @@ QuadPrecision_from_object(PyObject *value, QuadBackendType backend)
                 Py_DECREF(self);
                 return NULL;
             }
-            long long lval = PyLong_AsLongLong(py_int);
-            Py_DECREF(py_int);
 
-            if (backend == BACKEND_SLEEF) {
-                self->value.sleef_value = Sleef_cast_from_int64q1(lval);
-            }
-            else {
-                self->value.longdouble_value = (long double)lval;
-            }
-            return self;
+            QuadPrecisionObject *result = quad_from_py_int(py_int, backend, self);
+            Py_DECREF(py_int);
+            return result;
         }
         // Try as boolean
         else if (PyArray_IsScalar(value, Bool)) {
@@ -94,9 +134,16 @@ QuadPrecision_from_object(PyObject *value, QuadBackendType backend)
                 Py_DECREF(self);
                 return NULL;
             }
+
+            // Booleans are always 0 or 1, so no overflow check needed
             long long lval = PyLong_AsLongLong(py_int);
             Py_DECREF(py_int);
 
+            if (lval == -1 && PyErr_Occurred()) {
+                Py_DECREF(self);
+                return NULL;
+            }
+
             if (backend == BACKEND_SLEEF) {
                 self->value.sleef_value = Sleef_cast_from_int64q1(lval);
             }
@@ -145,7 +192,7 @@ QuadPrecision_from_object(PyObject *value, QuadBackendType backend)
             self->value.longdouble_value = (long double)dval;
         }
     }
-    else if (PyUnicode_CheckExact(value)) {
+    else if (PyUnicode_Check(value)) {
         const char *s = PyUnicode_AsUTF8(value);
         char *endptr = NULL;
         if (backend == BACKEND_SLEEF) {
@@ -161,18 +208,7 @@ QuadPrecision_from_object(PyObject *value, QuadBackendType backend)
         }
     }
     else if (PyLong_Check(value)) {
-        long long val = PyLong_AsLongLong(value);
-        if (val == -1 && PyErr_Occurred()) {
-            PyErr_SetString(PyExc_OverflowError, "Overflow Error, value out of range");
-            Py_DECREF(self);
-            return NULL;
-        }
-        if (backend == BACKEND_SLEEF) {
-            self->value.sleef_value = Sleef_cast_from_int64q1(val);
-        }
-        else {
-            self->value.longdouble_value = (long double)val;
-        }
+        return quad_from_py_int(value, backend, self);
     }
     else if (Py_TYPE(value) == &QuadPrecision_Type) {
         Py_DECREF(self);  // discard the default one

quaddtype/tests/test_quaddtype.py

@@ -16,6 +16,66 @@ def test_create_scalar_simple():
     assert isinstance(QuadPrecision(1), QuadPrecision)
 
 
+@pytest.mark.parametrize("int_val", [
+    # Very large integers that exceed long double range
+    2 ** 1024,
+    2 ** 2048,
+    10 ** 308,
+    10 ** 4000,
+    # Edge cases
+    0,
+    1,
+    -1,
+    # Negative large integers
+    -(2 ** 1024),
+])
+def test_create_scalar_from_large_int(int_val):
+    """Test that QuadPrecision can handle very large integers beyond long double range.
+
+    This test ensures that integers like 2**1024, which overflow standard long double,
+    are properly converted via string representation to QuadPrecision without raising
+    overflow errors. The conversion should match the string-based conversion.
+    """
+    # Convert large int to QuadPrecision
+    result = QuadPrecision(int_val)
+    assert isinstance(result, QuadPrecision)
+
+    # String conversion should give the same result
+    str_val = str(int_val)
+    result_from_str = QuadPrecision(str_val)
+
+    # Both conversions should produce the same value
+    # (can be inf==inf on some platforms for very large values)
+    assert result == result_from_str
+
+    # For zero and small values, verify exact conversion
+    if int_val == 0:
+        assert float(result) == 0.0
+    elif abs(int_val) == 1:
+        assert float(result) == float(int_val)
+
+
+def test_create_scalar_from_int_with_broken_str():
+    """Test that QuadPrecision handles errors when __str__ fails on large integers.
+
+    This test checks the error handling path in scalar.c where PyObject_Str(py_int)
+    returns NULL. We simulate this by subclassing int with a __str__ method
+    that raises an exception.
+    """
+    class BrokenInt(int):
+        def __str__(self):
+            raise RuntimeError("Intentionally broken __str__ method")
+
+    # Create an instance with a value that will overflow long long (> 2**63 - 1)
+    # This triggers the string conversion path in quad_from_py_int
+    broken_int = BrokenInt(2 ** 1024)
+
+    # When PyLong_AsLongLongAndOverflow returns overflow,
+    # it tries to convert to string, which should fail and propagate the error
+    with pytest.raises(RuntimeError, match="Intentionally broken __str__ method"):
+        QuadPrecision(broken_int)
+
+
 class TestQuadPrecisionArrayCreation:
     """Test suite for QuadPrecision array creation from sequences and arrays."""
 
@@ -248,6 +308,68 @@ def test_string_roundtrip():
         )
 
 
+def test_string_subclass_parsing():
+    """Test that QuadPrecision handles string subclasses correctly.
+
+    This tests the PyUnicode_Check path in scalar.c lines 195-209,
+    verifying that string subclasses work and that parsing errors
+    are properly handled.
+    """
+    class MyString(str):
+        """A custom string subclass"""
+        pass
+
+    # Test valid string subclass - should parse correctly
+    valid_str = MyString("3.14159265358979323846")
+    result = QuadPrecision(valid_str)
+    assert isinstance(result, QuadPrecision)
+    expected = QuadPrecision("3.14159265358979323846")
+    assert result == expected
+
+    # Test with scientific notation
+    sci_str = MyString("1.23e-100")
+    result = QuadPrecision(sci_str)
+    assert isinstance(result, QuadPrecision)
+
+    # Test with negative value
+    neg_str = MyString("-42.5")
+    result = QuadPrecision(neg_str)
+    assert float(result) == -42.5
+
+    # Test invalid string - should raise ValueError
+    invalid_str = MyString("not a number")
+    with pytest.raises(ValueError, match="Unable to parse string to QuadPrecision"):
+        QuadPrecision(invalid_str)
+
+    # Test partially valid string (has trailing garbage)
+    partial_str = MyString("3.14abc")
+    with pytest.raises(ValueError, match="Unable to parse string to QuadPrecision"):
+        QuadPrecision(partial_str)
+
+    # Test empty string
+    empty_str = MyString("")
+    with pytest.raises(ValueError, match="Unable to parse string to QuadPrecision"):
+        QuadPrecision(empty_str)
+
+    # Test string with leading garbage
+    leading_garbage = MyString("abc3.14")
+    with pytest.raises(ValueError, match="Unable to parse string to QuadPrecision"):
+        QuadPrecision(leading_garbage)
+
+    # Test special values
+    inf_str = MyString("inf")
+    result = QuadPrecision(inf_str)
+    assert np.isinf(float(result))
+
+    neg_inf_str = MyString("-inf")
+    result = QuadPrecision(neg_inf_str)
+    assert np.isinf(float(result)) and float(result) < 0
+
+    nan_str = MyString("nan")
+    result = QuadPrecision(nan_str)
+    assert np.isnan(float(result))
+
+
 @pytest.mark.parametrize("name,expected", [("pi", np.pi), ("e", np.e), ("log2e", np.log2(np.e)), ("log10e", np.log10(np.e)), ("ln2", np.log(2.0)), ("ln10", np.log(10.0))])
 def test_math_constant(name, expected):
     assert isinstance(getattr(numpy_quaddtype, name), QuadPrecision)