blob: 7a5758959e40f0cb4e846e9eedcd4f66b94aefab [file] [log] [blame]
// Copyright 2018 The LUCI Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package builtins
import (
"fmt"
"go.starlark.net/starlark"
"go.starlark.net/starlarkstruct"
)
var (
// Struct is struct(**kwargs) builtin.
//
// def struct(**kwargs):
// """Returns an immutable object with fields set to given values."""
Struct = starlark.NewBuiltin("struct", starlarkstruct.Make)
// GenStruct is genstruct(name) builtin.
//
// def genstruct(name):
// """Returns a callable constructor for "branded" struct instances."""
GenStruct = starlark.NewBuiltin("genstruct", func(_ *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
var name string
if err := starlark.UnpackArgs("genstruct", args, kwargs, "name", &name); err != nil {
return nil, err
}
return &ctor{name: name}, nil
})
// Ctor is ctor(obj) builtin.
//
// def ctor(obj):
// """Returns a constructor used to construct this struct or None."""
Ctor = starlark.NewBuiltin("ctor", func(_ *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
var obj starlark.Value
if err := starlark.UnpackArgs("ctor", args, kwargs, "obj", &obj); err != nil {
return nil, err
}
if st, ok := obj.(*starlarkstruct.Struct); ok {
return st.Constructor(), nil
}
return starlark.None, nil
})
)
// Ctor is a callable that produces starlark structs that have it as a
// constructor.
type ctor struct{ name string }
var _ starlark.Callable = (*ctor)(nil)
func (c *ctor) Name() string { return c.name }
func (c *ctor) String() string { return c.name }
func (c *ctor) Type() string { return "ctor" }
func (c *ctor) Freeze() {} // immutable
func (c *ctor) Truth() starlark.Bool { return starlark.True }
func (c *ctor) Hash() (uint32, error) { return 0, fmt.Errorf("unhashable: ctor") }
func (c *ctor) CallInternal(_ *starlark.Thread, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
if len(args) > 0 {
return nil, fmt.Errorf("%s: unexpected positional arguments", c)
}
return starlarkstruct.FromKeywords(c, kwargs), nil
}