| 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 | |
| 5 | package typeutil |
| 6 | |
| 7 | import ( |
| 8 | "go/ast" |
| 9 | "go/types" |
| 10 | |
| 11 | "golang.org/x/tools/go/ast/astutil" |
| 12 | "golang.org/x/tools/internal/typeparams" |
| 13 | ) |
| 14 | |
| 15 | // Callee returns the named target of a function call, if any: |
| 16 | // a function, method, builtin, or variable. |
| 17 | // |
| 18 | // Functions and methods may potentially have type parameters. |
| 19 | func Callee(info *types.Info, call *ast.CallExpr) types.Object { |
| 20 | fun := astutil.Unparen(call.Fun) |
| 21 | |
| 22 | // Look through type instantiation if necessary. |
| 23 | isInstance := false |
| 24 | switch fun.(type) { |
| 25 | case *ast.IndexExpr, *typeparams.IndexListExpr: |
| 26 | // When extracting the callee from an *IndexExpr, we need to check that |
| 27 | // it is a *types.Func and not a *types.Var. |
| 28 | // Example: Don't match a slice m within the expression `m[0]()`. |
| 29 | isInstance = true |
| 30 | fun, _, _, _ = typeparams.UnpackIndexExpr(fun) |
| 31 | } |
| 32 | |
| 33 | var obj types.Object |
| 34 | switch fun := fun.(type) { |
| 35 | case *ast.Ident: |
| 36 | obj = info.Uses[fun] // type, var, builtin, or declared func |
| 37 | case *ast.SelectorExpr: |
| 38 | if sel, ok := info.Selections[fun]; ok { |
| 39 | obj = sel.Obj() // method or field |
| 40 | } else { |
| 41 | obj = info.Uses[fun.Sel] // qualified identifier? |
| 42 | } |
| 43 | } |
| 44 | if _, ok := obj.(*types.TypeName); ok { |
| 45 | return nil // T(x) is a conversion, not a call |
| 46 | } |
| 47 | // A Func is required to match instantiations. |
| 48 | if _, ok := obj.(*types.Func); isInstance && !ok { |
| 49 | return nil // Was not a Func. |
| 50 | } |
| 51 | return obj |
| 52 | } |
| 53 | |
| 54 | // StaticCallee returns the target (function or method) of a static function |
| 55 | // call, if any. It returns nil for calls to builtins. |
| 56 | // |
| 57 | // Note: for calls of instantiated functions and methods, StaticCallee returns |
| 58 | // the corresponding generic function or method on the generic type. |
| 59 | func StaticCallee(info *types.Info, call *ast.CallExpr) *types.Func { |
| 60 | if f, ok := Callee(info, call).(*types.Func); ok && !interfaceMethod(f) { |
| 61 | return f |
| 62 | } |
| 63 | return nil |
| 64 | } |
| 65 | |
| 66 | func interfaceMethod(f *types.Func) bool { |
| 67 | recv := f.Type().(*types.Signature).Recv() |
| 68 | return recv != nil && types.IsInterface(recv.Type()) |
| 69 | } |
| 70 |
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