builtin: Implement builtin_iter

Author: corona10

builtin/builtin.go

@@ -44,7 +44,7 @@ func init() {
 		// py.MustNewMethod("input", builtin_input, 0, input_doc),
 		// py.MustNewMethod("isinstance", builtin_isinstance, 0, isinstance_doc),
 		// py.MustNewMethod("issubclass", builtin_issubclass, 0, issubclass_doc),
-		// py.MustNewMethod("iter", builtin_iter, 0, iter_doc),
+		py.MustNewMethod("iter", builtin_iter, 0, iter_doc),
 		py.MustNewMethod("len", builtin_len, 0, len_doc),
 		py.MustNewMethod("locals", py.InternalMethodLocals, 0, locals_doc),
 		py.MustNewMethod("max", builtin_max, 0, max_doc),
@@ -762,6 +762,39 @@ object.
 The globals and locals are dictionaries, defaulting to the current
 globals and locals.  If only globals is given, locals defaults to it.`
 
+const iter_doc = `iter(iterable) -> iterator
+iter(callable, sentinel) -> iterator
+
+Get an iterator from an object.  In the first form, the argument must
+supply its own iterator, or be a sequence.
+In the second form, the callable is called until it returns the sentinel.
+`
+
+func builtin_iter(self py.Object, args py.Tuple) (py.Object, error) {
+	nArgs := len(args)
+	if nArgs < 1 {
+		return nil, py.ExceptionNewf(py.TypeError,
+			"iter expected at least 1 arguments, got %d",
+			nArgs)
+	} else if nArgs > 2 {
+		return nil, py.ExceptionNewf(py.TypeError,
+			"iter expected at most 2 arguments, got %d",
+			nArgs)
+	}
+
+	v := args[0]
+	if nArgs == 1 {
+		return py.Iter(v)
+	}
+	_, ok := v.(*py.Function)
+	if !ok {
+		return nil, py.ExceptionNewf(py.TypeError,
+			"iter(v, w): v must be callable")
+	}
+	return nil, py.ExceptionNewf(py.NotImplementedError,
+		"Not implemented yet")
+}
+
 // For code see vm/builtin.go
 
 const len_doc = `len(object) -> integer