1// Copyright 2018 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package typeutil
6
7import (
8	"go/ast"
9	"go/types"
10
11	"golang.org/x/tools/go/ast/astutil"
12)
13
14// Callee returns the named target of a function call, if any:
15// a function, method, builtin, or variable.
16func Callee(info *types.Info, call *ast.CallExpr) types.Object {
17	var obj types.Object
18	switch fun := astutil.Unparen(call.Fun).(type) {
19	case *ast.Ident:
20		obj = info.Uses[fun] // type, var, builtin, or declared func
21	case *ast.SelectorExpr:
22		if sel, ok := info.Selections[fun]; ok {
23			obj = sel.Obj() // method or field
24		} else {
25			obj = info.Uses[fun.Sel] // qualified identifier?
26		}
27	}
28	if _, ok := obj.(*types.TypeName); ok {
29		return nil // T(x) is a conversion, not a call
30	}
31	return obj
32}
33
34// StaticCallee returns the target (function or method) of a static
35// function call, if any. It returns nil for calls to builtins.
36func StaticCallee(info *types.Info, call *ast.CallExpr) *types.Func {
37	if f, ok := Callee(info, call).(*types.Func); ok && !interfaceMethod(f) {
38		return f
39	}
40	return nil
41}
42
43func interfaceMethod(f *types.Func) bool {
44	recv := f.Type().(*types.Signature).Recv()
45	return recv != nil && types.IsInterface(recv.Type())
46}
47