| 1 | // Copyright 2022 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 | package ifaceassert |
| 5 | |
| 6 | import ( |
| 7 | "go/types" |
| 8 | |
| 9 | "golang.org/x/tools/internal/typeparams" |
| 10 | ) |
| 11 | |
| 12 | // isParameterized reports whether typ contains any of the type parameters of tparams. |
| 13 | // |
| 14 | // NOTE: Adapted from go/types/infer.go. If that is exported in a future release remove this copy. |
| 15 | func isParameterized(typ types.Type) bool { |
| 16 | w := tpWalker{ |
| 17 | seen: make(map[types.Type]bool), |
| 18 | } |
| 19 | return w.isParameterized(typ) |
| 20 | } |
| 21 | |
| 22 | type tpWalker struct { |
| 23 | seen map[types.Type]bool |
| 24 | } |
| 25 | |
| 26 | func (w *tpWalker) isParameterized(typ types.Type) (res bool) { |
| 27 | // detect cycles |
| 28 | if x, ok := w.seen[typ]; ok { |
| 29 | return x |
| 30 | } |
| 31 | w.seen[typ] = false |
| 32 | defer func() { |
| 33 | w.seen[typ] = res |
| 34 | }() |
| 35 | |
| 36 | switch t := typ.(type) { |
| 37 | case nil, *types.Basic: // TODO(gri) should nil be handled here? |
| 38 | break |
| 39 | |
| 40 | case *types.Array: |
| 41 | return w.isParameterized(t.Elem()) |
| 42 | |
| 43 | case *types.Slice: |
| 44 | return w.isParameterized(t.Elem()) |
| 45 | |
| 46 | case *types.Struct: |
| 47 | for i, n := 0, t.NumFields(); i < n; i++ { |
| 48 | if w.isParameterized(t.Field(i).Type()) { |
| 49 | return true |
| 50 | } |
| 51 | } |
| 52 | |
| 53 | case *types.Pointer: |
| 54 | return w.isParameterized(t.Elem()) |
| 55 | |
| 56 | case *types.Tuple: |
| 57 | n := t.Len() |
| 58 | for i := 0; i < n; i++ { |
| 59 | if w.isParameterized(t.At(i).Type()) { |
| 60 | return true |
| 61 | } |
| 62 | } |
| 63 | |
| 64 | case *types.Signature: |
| 65 | // t.tparams may not be nil if we are looking at a signature |
| 66 | // of a generic function type (or an interface method) that is |
| 67 | // part of the type we're testing. We don't care about these type |
| 68 | // parameters. |
| 69 | // Similarly, the receiver of a method may declare (rather then |
| 70 | // use) type parameters, we don't care about those either. |
| 71 | // Thus, we only need to look at the input and result parameters. |
| 72 | return w.isParameterized(t.Params()) || w.isParameterized(t.Results()) |
| 73 | |
| 74 | case *types.Interface: |
| 75 | for i, n := 0, t.NumMethods(); i < n; i++ { |
| 76 | if w.isParameterized(t.Method(i).Type()) { |
| 77 | return true |
| 78 | } |
| 79 | } |
| 80 | terms, err := typeparams.InterfaceTermSet(t) |
| 81 | if err != nil { |
| 82 | panic(err) |
| 83 | } |
| 84 | for _, term := range terms { |
| 85 | if w.isParameterized(term.Type()) { |
| 86 | return true |
| 87 | } |
| 88 | } |
| 89 | |
| 90 | case *types.Map: |
| 91 | return w.isParameterized(t.Key()) || w.isParameterized(t.Elem()) |
| 92 | |
| 93 | case *types.Chan: |
| 94 | return w.isParameterized(t.Elem()) |
| 95 | |
| 96 | case *types.Named: |
| 97 | list := typeparams.NamedTypeArgs(t) |
| 98 | for i, n := 0, list.Len(); i < n; i++ { |
| 99 | if w.isParameterized(list.At(i)) { |
| 100 | return true |
| 101 | } |
| 102 | } |
| 103 | |
| 104 | case *typeparams.TypeParam: |
| 105 | return true |
| 106 | |
| 107 | default: |
| 108 | panic(t) // unreachable |
| 109 | } |
| 110 | |
| 111 | return false |
| 112 | } |
| 113 |
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