| // Copyright 2021 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| // The genericfeatures package provides utilities for detecting usage of |
| // generic programming in Go packages. |
| package genericfeatures |
| |
| import ( |
| "go/ast" |
| "go/types" |
| "strings" |
| |
| "golang.org/x/tools/go/ast/inspector" |
| "golang.org/x/tools/internal/typeparams" |
| ) |
| |
| // Features is a set of flags reporting which features of generic Go code a |
| // package uses, or 0. |
| type Features int |
| |
| const ( |
| // GenericTypeDecls indicates whether the package declares types with type |
| // parameters. |
| GenericTypeDecls Features = 1 << iota |
| |
| // GenericFuncDecls indicates whether the package declares functions with |
| // type parameters. |
| GenericFuncDecls |
| |
| // EmbeddedTypeSets indicates whether the package declares interfaces that |
| // contain structural type restrictions, i.e. are not fully described by |
| // their method sets. |
| EmbeddedTypeSets |
| |
| // TypeInstantiation indicates whether the package instantiates any generic |
| // types. |
| TypeInstantiation |
| |
| // FuncInstantiation indicates whether the package instantiates any generic |
| // functions. |
| FuncInstantiation |
| ) |
| |
| func (f Features) String() string { |
| var feats []string |
| if f&GenericTypeDecls != 0 { |
| feats = append(feats, "typeDecl") |
| } |
| if f&GenericFuncDecls != 0 { |
| feats = append(feats, "funcDecl") |
| } |
| if f&EmbeddedTypeSets != 0 { |
| feats = append(feats, "typeSet") |
| } |
| if f&TypeInstantiation != 0 { |
| feats = append(feats, "typeInstance") |
| } |
| if f&FuncInstantiation != 0 { |
| feats = append(feats, "funcInstance") |
| } |
| return "features{" + strings.Join(feats, ",") + "}" |
| } |
| |
| // ForPackage computes which generic features are used directly by the |
| // package being analyzed. |
| func ForPackage(inspect *inspector.Inspector, info *types.Info) Features { |
| nodeFilter := []ast.Node{ |
| (*ast.FuncType)(nil), |
| (*ast.InterfaceType)(nil), |
| (*ast.ImportSpec)(nil), |
| (*ast.TypeSpec)(nil), |
| } |
| |
| var direct Features |
| |
| inspect.Preorder(nodeFilter, func(node ast.Node) { |
| switch n := node.(type) { |
| case *ast.FuncType: |
| if tparams := typeparams.ForFuncType(n); tparams != nil { |
| direct |= GenericFuncDecls |
| } |
| case *ast.InterfaceType: |
| tv := info.Types[n] |
| if iface, _ := tv.Type.(*types.Interface); iface != nil && !typeparams.IsMethodSet(iface) { |
| direct |= EmbeddedTypeSets |
| } |
| case *ast.TypeSpec: |
| if tparams := typeparams.ForTypeSpec(n); tparams != nil { |
| direct |= GenericTypeDecls |
| } |
| } |
| }) |
| |
| instances := typeparams.GetInstances(info) |
| for _, inst := range instances { |
| switch inst.Type.(type) { |
| case *types.Named: |
| direct |= TypeInstantiation |
| case *types.Signature: |
| direct |= FuncInstantiation |
| } |
| } |
| return direct |
| } |