Compiler conversions

src/CSnakes.Runtime.Tests/Python/PyObjectTests.cs

@@ -1,4 +1,5 @@
 using CSnakes.Runtime.Python;
+using System.Collections;
 
 namespace CSnakes.Runtime.Tests.Python;
 public class PyObjectTests : RuntimeTestBase
@@ -61,7 +62,8 @@ public void TestObjectIsNone()
     }
 
     [Fact]
-    public void TestObjectIsSmallIntegers() {
+    public void TestObjectIsSmallIntegers()
+    {
         // Small numbers are the same object in Python, weird implementation detail.
         var obj1 = PyObject.From(42);
         var obj2 = PyObject.From(42);
@@ -157,4 +159,22 @@ public void TestObjectNotStrictInequality(object? o1, object? o2, bool expectedL
         Assert.Equal(expectedLT, obj1 <= obj2);
         Assert.Equal(expectedGT, obj1 >= obj2);
     }
+
+    [Fact]
+    public void TestAsCollection()
+    {
+        using PyObject o = PyObject.From<IEnumerable<string>>(new[] { "Hello", "World" })!;
+        var collection = o.AsCollection<IReadOnlyCollection<string>, string>();
+        Assert.NotNull(collection);
+        Assert.Equal(2, collection!.Count());
+    }
+
+    [Fact]
+    public void TestAsDictionary()
+    {
+        using PyObject o = PyObject.From<IDictionary<string, string>>(new Dictionary<string, string> { { "Hello", "World" } })!;
+        var dictionary = o.AsDictionary<IReadOnlyDictionary<string, string>, string, string>();
+        Assert.NotNull(dictionary);
+        Assert.Equal("World", dictionary!["Hello"]);
+    }
 }

src/CSnakes.Runtime.Tests/RuntimeTestBase.cs

@@ -20,7 +20,8 @@ public RuntimeTestBase()
                 var pb = services.WithPython();
                 pb.WithHome(Environment.CurrentDirectory);
 
-                pb.FromNuGet(pythonVersionWindows)
+                pb
+                  .FromNuGet(pythonVersionWindows)
                   .FromMacOSInstallerLocator(pythonVersionMacOS)
                   .FromEnvironmentVariable("Python3_ROOT_DIR", pythonVersionLinux); // This last one is for GitHub Actions
 

src/CSnakes.Runtime/CPython/Dict.cs

@@ -28,7 +28,7 @@ internal static nint PackDict(Span<string> kwnames, Span<IntPtr> kwvalues)
             int result = PyDict_SetItemRaw(dict, keyObj, kwvalues[i]);
             if (result == -1)
             {
-                PyObject.ThrowPythonExceptionAsClrException();
+                throw PyObject.ThrowPythonExceptionAsClrException();
             }
             Py_DecRefRaw(keyObj);
         }
@@ -55,7 +55,7 @@ internal static nint PyDict_GetItem(PyObject dict, PyObject key)
         var result = PyDict_GetItem_(dict, key);
         if (result == IntPtr.Zero)
         {
-            PyObject.ThrowPythonExceptionAsClrException();
+            throw PyObject.ThrowPythonExceptionAsClrException();
         }
         Py_IncRefRaw(result);
         return result;

src/CSnakes.Runtime/CPython/Float.cs

@@ -15,13 +15,23 @@ internal unsafe partial class CPythonAPI
     [LibraryImport(PythonLibraryName)]
     internal static partial nint PyFloat_FromDouble(double value);
 
+    internal static double PyFloat_AsDouble(PyObject p)
+    {
+        double result = PyFloat_AsDouble_(p);
+        if (result == -1 && PyErr_Occurred())
+        {
+            throw PyObject.ThrowPythonExceptionAsClrException("Error converting Python object to double, check that the object was a Python float. See InnerException for details.");
+        }
+        return result;
+    }
+
     /// <summary>
     /// Convery a PyFloat to a C double
     /// </summary>
     /// <param name="p"></param>
     /// <returns>The double value</returns>
-    [LibraryImport(PythonLibraryName)]
-    internal static partial double PyFloat_AsDouble(PyObject obj);
+    [LibraryImport(PythonLibraryName, EntryPoint = "PyFloat_AsDouble")]
+    private static partial double PyFloat_AsDouble_(PyObject obj);
 
     internal static bool IsPyFloat(PyObject p)
     {

src/CSnakes.Runtime/CPython/Import.cs

@@ -26,7 +26,7 @@ protected static nint GetBuiltin(string name)
         nint attr = PyObject_GetAttrRaw(module, pyAttrName);
         if (attr == IntPtr.Zero)
         {
-            PyObject.ThrowPythonExceptionAsClrException();
+            throw PyObject.ThrowPythonExceptionAsClrException();
         }
         Py_DecRefRaw(pyName);
         Py_DecRefRaw(pyAttrName);

src/CSnakes.Runtime/CPython/List.cs

@@ -34,7 +34,7 @@ internal static nint PyList_GetItem(PyObject obj, nint pos)
         nint item = PyList_GetItem_(obj, pos);
         if (item == IntPtr.Zero)
         {
-            PyObject.ThrowPythonExceptionAsClrException();
+            throw PyObject.ThrowPythonExceptionAsClrException();
         }
         Py_IncRefRaw(item);
         return item;

src/CSnakes.Runtime/CPython/Long.cs

@@ -13,11 +13,41 @@ internal unsafe partial class CPythonAPI
     [LibraryImport(PythonLibraryName)]
     internal static partial nint PyLong_FromLongLong(long v);
 
-    [LibraryImport(PythonLibraryName)]
-    internal static partial long PyLong_AsLongLong(PyObject p);
+    /// <summary>
+    /// Calls PyLong_AsLongLong and throws a Python Exception if an error occurs.
+    /// </summary>
+    /// <param name="p"></param>
+    /// <returns></returns>
+    internal static long PyLong_AsLongLong(PyObject p)
+    {
+        long result = PyLong_AsLongLong_(p);
+        if (result == -1 && PyErr_Occurred())
+        {
+            throw PyObject.ThrowPythonExceptionAsClrException("Error converting Python object to int, check that the object was a Python int or that the value wasn't too large. See InnerException for details.");
+        }
+        return result;
+    }
 
-    [LibraryImport(PythonLibraryName)]
-    internal static partial int PyLong_AsLong(PyObject p);
+    [LibraryImport(PythonLibraryName, EntryPoint = "PyLong_AsLongLong")]
+    private static partial long PyLong_AsLongLong_(PyObject p);
+
+    /// <summary>
+    /// Calls PyLong_AsLong and throws a Python Exception if an error occurs.
+    /// </summary>
+    /// <param name="p"></param>
+    /// <returns></returns>
+    internal static long PyLong_AsLong(PyObject p)
+    {
+        long result = PyLong_AsLong_(p);
+        if (result == -1 && PyErr_Occurred())
+        {
+            throw PyObject.ThrowPythonExceptionAsClrException("Error converting Python object to int, check that the object was a Python int or that the value wasn't too large. See InnerException for details.");
+        }
+        return result;
+    }
+
+    [LibraryImport(PythonLibraryName, EntryPoint = "PyLong_AsLong")]
+    private static partial int PyLong_AsLong_(PyObject p);
 
     internal static bool IsPyLong(PyObject p)
     {

src/CSnakes.Runtime/CPython/Object.cs

@@ -75,7 +75,7 @@ internal static bool PyObject_IsInstance(PyObject ob, IntPtr type)
         int result = PyObject_IsInstance_(ob, type);
         if (result == -1)
         {
-            PyObject.ThrowPythonExceptionAsClrException();
+            throw PyObject.ThrowPythonExceptionAsClrException();
         }
         return result == 1;
     }
@@ -173,7 +173,7 @@ internal static bool PyObject_RichCompare(PyObject ob1, PyObject ob2, RichCompar
         int result = PyObject_RichCompareBool(ob1, ob2, comparisonType);
         if (result == -1)
         {
-            PyObject.ThrowPythonExceptionAsClrException();
+            throw PyObject.ThrowPythonExceptionAsClrException();
         }
         return result == 1;
     }

src/CSnakes.Runtime/CPython/Tuple.cs

@@ -72,7 +72,7 @@ internal static nint PyTuple_GetItemWithNewRef(PyObject ob, nint pos)
         nint item = PyTuple_GetItem(ob, pos);
         if (item == IntPtr.Zero)
         {
-            PyObject.ThrowPythonExceptionAsClrException();
+            throw PyObject.ThrowPythonExceptionAsClrException();
         }
         Py_IncRefRaw(item);
         return item;
@@ -83,7 +83,7 @@ internal static nint PyTuple_GetItemWithNewRefRaw(nint ob, nint pos)
         nint item = PyTuple_GetItemRaw(ob, pos);
         if (item == IntPtr.Zero)
         {
-            PyObject.ThrowPythonExceptionAsClrException();
+            throw PyObject.ThrowPythonExceptionAsClrException();
         }
         Py_IncRefRaw(item);
         return item;

src/CSnakes.Runtime/CPython/Unicode.cs

@@ -17,14 +17,25 @@ internal static nint AsPyUnicodeObject(string s)
     [LibraryImport(PythonLibraryName)]
     internal static partial nint PyUnicode_DecodeUTF16(char* str, nint size, IntPtr errors, IntPtr byteorder);
 
+    /// <summary>
+    /// Calls PyUnicode_AsUTF8 and throws a Python Exception if an error occurs.
+    /// </summary>
+    /// <param name="s"></param>
+    /// <returns></returns>
+    internal static string PyUnicode_AsUTF8(PyObject s)
+    {
+        var result = PyUnicode_AsUTF8_(s);
+        return result is null ? throw PyObject.ThrowPythonExceptionAsClrException() : result;
+    }
+
     /// <summary>
     /// Convert the string object to a UTF-8 encoded string and return a pointer to the internal buffer.
     /// This function does a type check and returns null if the object is not a string.
     /// </summary>
     /// <param name="s"></param>
     /// <returns></returns>
-    [LibraryImport(PythonLibraryName, StringMarshalling = StringMarshalling.Custom, StringMarshallingCustomType = typeof(NonFreeUtf8StringMarshaller))]
-    internal static partial string? PyUnicode_AsUTF8(PyObject s);
+    [LibraryImport(PythonLibraryName, StringMarshalling = StringMarshalling.Custom, StringMarshallingCustomType = typeof(NonFreeUtf8StringMarshaller), EntryPoint = "PyUnicode_AsUTF8")]
+    private static partial string? PyUnicode_AsUTF8_(PyObject s);
 
     [LibraryImport(PythonLibraryName, StringMarshalling = StringMarshalling.Custom, StringMarshallingCustomType = typeof(NonFreeUtf8StringMarshaller), EntryPoint = "PyUnicode_AsUTF8")]
     internal static partial string? PyUnicode_AsUTF8Raw(nint s);

src/CSnakes.Runtime/PyObjectTypeConverter.BigInteger.cs

@@ -5,11 +5,11 @@
 namespace CSnakes.Runtime;
 internal partial class PyObjectTypeConverter
 {
-    private static object? ConvertToBigInteger(PyObject pyObject, Type destinationType) =>
+    internal static BigInteger ConvertToBigInteger(PyObject pyObject, Type destinationType) =>
         // There is no practical API for this in CPython. Use str() instead. 
         BigInteger.Parse(pyObject.ToString());
 
-    private static PyObject ConvertFromBigInteger(BigInteger integer)
+    internal static PyObject ConvertFromBigInteger(BigInteger integer)
     {
         using PyObject pyUnicode = PyObject.Create(CPythonAPI.AsPyUnicodeObject(integer.ToString()));
         return PyObject.Create(CPythonAPI.PyLong_FromUnicodeObject(pyUnicode, 10));

src/CSnakes.Runtime/PyObjectTypeConverter.Dictionary.cs

@@ -6,7 +6,7 @@
 namespace CSnakes.Runtime;
 internal partial class PyObjectTypeConverter
 {
-    private object? ConvertToDictionary(PyObject pyObject, Type destinationType, bool useMappingProtocol = false)
+    private object ConvertToDictionary(PyObject pyObject, Type destinationType, bool useMappingProtocol = false)
     {
         using PyObject items = useMappingProtocol ? 
             PyObject.Create(CPythonAPI.PyMapping_Items(pyObject)) : 
@@ -45,9 +45,9 @@ internal partial class PyObjectTypeConverter
                 if (keyAsString is null)
                 {
                     CPythonAPI.Py_DecRefRaw(itemKey);
-                    PyObject.ThrowPythonExceptionAsClrException();
+                    throw PyObject.ThrowPythonExceptionAsClrException();
                 }
-                object? convertedValue = ConvertTo(value, valueType);
+                object? convertedValue = value.As(valueType);
 
                 dict.Add(keyAsString!, convertedValue);
                 CPythonAPI.Py_DecRefRaw(itemKey);
@@ -56,8 +56,8 @@ internal partial class PyObjectTypeConverter
                 using PyObject key = PyObject.Create(CPythonAPI.PyTuple_GetItemWithNewRefRaw(kvpTuple, 0));
                 using PyObject value = PyObject.Create(CPythonAPI.PyTuple_GetItemWithNewRefRaw(kvpTuple, 1));
 
-                object? convertedKey = ConvertTo(key, keyType);
-                object? convertedValue = ConvertTo(value, valueType);
+                object? convertedKey = key.As(keyType);
+                object? convertedValue = value.As(valueType);
 
                 dict.Add(convertedKey!, convertedValue);
             }
@@ -67,6 +67,28 @@ internal partial class PyObjectTypeConverter
         return typeInfo.ReturnTypeConstructor.Invoke([dict]);
     }
 
+    internal IReadOnlyDictionary<TKey, TValue> ConvertToDictionary<TKey, TValue>(PyObject pyObject) where TKey : notnull
+    {
+        using PyObject items = PyObject.Create(CPythonAPI.PyMapping_Items(pyObject));
+
+        var dict = new Dictionary<TKey, TValue>();
+        nint itemsLength = CPythonAPI.PyList_Size(items);
+        for (nint i = 0; i < itemsLength; i++)
+        {
+            nint kvpTuple = CPythonAPI.PyList_GetItem(items, i);
+            using PyObject key = PyObject.Create(CPythonAPI.PyTuple_GetItemWithNewRefRaw(kvpTuple, 0));
+            using PyObject value = PyObject.Create(CPythonAPI.PyTuple_GetItemWithNewRefRaw(kvpTuple, 1));
+
+            TKey convertedKey = key.As<TKey>();
+            TValue convertedValue = value.As<TValue>();
+
+            dict.Add(convertedKey, convertedValue);
+            CPythonAPI.Py_DecRefRaw(kvpTuple);
+        }
+
+        return dict;
+    }
+
     private PyObject ConvertFromDictionary(IDictionary dictionary)
     {
         int len = dictionary.Keys.Count;

src/CSnakes.Runtime/PyObjectTypeConverter.Generator.cs

@@ -1,11 +1,17 @@
+using CSnakes.Runtime.CPython;
 using CSnakes.Runtime.Python;
 using System.Reflection;
 
 namespace CSnakes.Runtime;
 internal partial class PyObjectTypeConverter
 {
-    private object? ConvertToGeneratorIterator(PyObject pyObject, Type destinationType)
+    internal object ConvertToGeneratorIterator(PyObject pyObject, Type destinationType)
     {
+        if (!CPythonAPI.IsPyGenerator(pyObject))
+        {
+            throw new InvalidCastException($"Cannot convert {pyObject.GetPythonType()} to a generator.");
+        }
+
         if (!knownDynamicTypes.TryGetValue(destinationType, out DynamicTypeInfo? typeInfo))
         {
             Type item1Type = destinationType.GetGenericArguments()[0];