| // 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. |
| |
| //go:build typeparams |
| // +build typeparams |
| |
| package typeparams |
| |
| import ( |
| "fmt" |
| "go/ast" |
| ) |
| |
| const Enabled = true |
| |
| func PackExpr(list []ast.Expr) ast.Expr { |
| switch len(list) { |
| case 0: |
| // Return an empty ListExpr here, rather than nil, as IndexExpr.Index must |
| // never be nil. |
| // TODO(rFindley) would a BadExpr be more appropriate here? |
| return &ast.ListExpr{} |
| case 1: |
| return list[0] |
| default: |
| return &ast.ListExpr{ElemList: list} |
| } |
| } |
| |
| // TODO(gri) Should find a more efficient solution that doesn't |
| // require introduction of a new slice for simple |
| // expressions. |
| func UnpackExpr(x ast.Expr) []ast.Expr { |
| if x, _ := x.(*ast.ListExpr); x != nil { |
| return x.ElemList |
| } |
| if x != nil { |
| return []ast.Expr{x} |
| } |
| return nil |
| } |
| |
| func IsListExpr(n ast.Node) bool { |
| _, ok := n.(*ast.ListExpr) |
| return ok |
| } |
| |
| func Get(n ast.Node) *ast.FieldList { |
| switch n := n.(type) { |
| case *ast.TypeSpec: |
| return n.TParams |
| case *ast.FuncType: |
| return n.TParams |
| default: |
| panic(fmt.Sprintf("node type %T has no type parameters", n)) |
| } |
| } |
| |
| func Set(n ast.Node, params *ast.FieldList) { |
| switch n := n.(type) { |
| case *ast.TypeSpec: |
| n.TParams = params |
| case *ast.FuncType: |
| n.TParams = params |
| default: |
| panic(fmt.Sprintf("node type %T has no type parameters", n)) |
| } |
| } |