cffi: Implement wrapping of functions with slices/arrays of builtin arguments

Author: corona10

_examples/arrays/arrays.go

@@ -0,0 +1,17 @@
+// Copyright 2017 The go-python Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package arrays
+
+func IntSum(a [4]int) int {
+	sum := 0
+	for i := 0; i < len(a); i++ {
+		sum += a[i]
+	}
+	return sum
+}
+
+func CreateArray() [4]int {
+	return [4]int{1, 2, 3, 4}
+}

_examples/arrays/test.py

@@ -0,0 +1,13 @@
+# Copyright 2017 The go-python Authors.  All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+from __future__ import print_function
+import arrays
+
+a = [1,2,3,4]
+b = arrays.CreateArray()
+print ("Python list:", a)
+print ("Go array: ", b)
+print ("arrays.IntSum from Python list:", arrays.IntSum(a))
+print ("arrays.IntSum from Go array:", arrays.IntSum(b))

_examples/slices/slices.go

@@ -0,0 +1,17 @@
+// Copyright 2017 The go-python Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package slices
+
+func IntSum(s []int) int {
+	sum := 0
+	for _, value := range s {
+		sum += value
+	}
+	return sum
+}
+
+func CreateSlice() []int {
+	return []int{1, 2, 3, 4}
+}

_examples/slices/test.py

@@ -0,0 +1,13 @@
+# Copyright 2017 The go-python Authors.  All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+from __future__ import print_function
+import slices
+
+a = [1,2,3,4]
+b = slices.CreateSlice()
+print ("Python list:", a)
+print ("Go slice: ", b)
+print ("slices.IntSum from Python list:", slices.IntSum(a))
+print ("slices.IntSum from Go slice:", slices.IntSum(b))

bind/gencffi_type.go

@@ -227,8 +227,50 @@ func (g *cffiGen) genTypeConverter(sym *symbol) {
 	g.wrapper.Printf("@staticmethod\n")
 	g.wrapper.Printf("def cffi_cgopy_cnv_py2c_%[1]s(o):\n", sym.id)
 	g.wrapper.Indent()
+	g.wrapper.Printf("if type(o) is %[1]s:\n", typename)
+	g.wrapper.Indent()
 	g.wrapper.Printf("return o.cgopy\n")
 	g.wrapper.Outdent()
+	switch {
+	case sym.isBasic():
+		g.wrapper.Printf("return _cffi_helper.cffi_cgopy_cnv_py2c_%[1]s(o)\n", sym.goname)
+	case sym.isArray():
+		g.wrapper.Printf("if not isinstance(o, collections.Iterable):\n")
+		g.wrapper.Indent()
+		g.wrapper.Printf("raise TypeError('%[1]s.__init__ takes a sequence as argument')\n", sym.goname)
+		g.wrapper.Outdent()
+		typ := sym.GoType().Underlying().(*types.Array)
+		esym := g.pkg.syms.symtype(typ.Elem())
+		g.wrapper.Printf("if len(o) > %[1]d:\n", typ.Len())
+		g.wrapper.Indent()
+		g.wrapper.Printf("raise ValueError('%[1]s.__init__ takes a sequence of size at most %[2]d')\n",
+			sym.goname,
+			typ.Len(),
+		)
+		g.wrapper.Outdent()
+		g.wrapper.Printf("c = _cffi_helper.lib.cgo_func_%[1]s_new()\n", sym.id)
+		g.wrapper.Printf("for idx, elt in enumerate(o):\n")
+		g.wrapper.Indent()
+		g.wrapper.Printf("pyitem = _cffi_helper.cffi_%[1]s(elt)\n", esym.py2c)
+		g.wrapper.Printf("_cffi_helper.lib.cgo_func_%[1]s_ass_item(c, idx, pyitem)\n", sym.id)
+		g.wrapper.Outdent()
+		g.wrapper.Printf("return c\n")
+	case sym.isSlice():
+		g.wrapper.Printf("if not isinstance(o, collections.Iterable):\n")
+		g.wrapper.Indent()
+		g.wrapper.Printf("raise TypeError('%[1]s.__init__ takes a sequence as argument')\n", sym.goname)
+		g.wrapper.Outdent()
+		typ := sym.GoType().Underlying().(*types.Slice)
+		esym := g.pkg.syms.symtype(typ.Elem())
+		g.wrapper.Printf("c = _cffi_helper.lib.cgo_func_%[1]s_new()\n", sym.id)
+		g.wrapper.Printf("for elt in o:\n")
+		g.wrapper.Indent()
+		g.wrapper.Printf("pyitem = _cffi_helper.cffi_%[1]s(elt)\n", esym.py2c)
+		g.wrapper.Printf("_cffi_helper.lib.cgo_func_%[1]s_append(c, pyitem)\n", sym.id)
+		g.wrapper.Outdent()
+		g.wrapper.Printf("return c\n")
+	}
+	g.wrapper.Outdent()
 	g.wrapper.Printf("\n")
 	g.wrapper.Printf("@staticmethod\n")
 	g.wrapper.Printf("def cffi_cgopy_cnv_c2py_%[1]s(c):\n", sym.id)

main_test.go

@@ -932,3 +932,27 @@ pyerrors.Div(5, 2) = 2
 `),
 	})
 }
+
+func TestBuiltinArrays(t *testing.T) {
+	t.Parallel()
+	testPkgWithCFFI(t, pkg{
+		path: "_examples/arrays",
+		want: []byte(`Python list: [1, 2, 3, 4]
+Go array:  [4]int{1, 2, 3, 4}
+arrays.IntSum from Python list: 10
+arrays.IntSum from Go array: 10
+`),
+	})
+}
+
+func TestBuiltinSlices(t *testing.T) {
+	t.Parallel()
+	testPkgWithCFFI(t, pkg{
+		path: "_examples/slices",
+		want: []byte(`Python list: [1, 2, 3, 4]
+Go slice:  []int{1, 2, 3, 4}
+slices.IntSum from Python list: 10
+slices.IntSum from Go slice: 10
+`),
+	})
+}