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dnscrypt-proxy/vendor/honnef.co/go/tools/unused/implements.go
2021-07-03 10:56:53 +02:00

83 lines
2.0 KiB
Go

package unused
import "go/types"
// lookupMethod returns the index of and method with matching package and name, or (-1, nil).
func lookupMethod(T *types.Interface, pkg *types.Package, name string) (int, *types.Func) {
if name != "_" {
for i := 0; i < T.NumMethods(); i++ {
m := T.Method(i)
if sameId(m, pkg, name) {
return i, m
}
}
}
return -1, nil
}
func sameId(obj types.Object, pkg *types.Package, name string) bool {
// spec:
// "Two identifiers are different if they are spelled differently,
// or if they appear in different packages and are not exported.
// Otherwise, they are the same."
if name != obj.Name() {
return false
}
// obj.Name == name
if obj.Exported() {
return true
}
// not exported, so packages must be the same (pkg == nil for
// fields in Universe scope; this can only happen for types
// introduced via Eval)
if pkg == nil || obj.Pkg() == nil {
return pkg == obj.Pkg()
}
// pkg != nil && obj.pkg != nil
return pkg.Path() == obj.Pkg().Path()
}
func (g *graph) implements(V types.Type, T *types.Interface, msV *types.MethodSet) ([]*types.Selection, bool) {
// fast path for common case
if T.Empty() {
return nil, true
}
if ityp, _ := V.Underlying().(*types.Interface); ityp != nil {
// TODO(dh): is this code reachable?
for i := 0; i < T.NumMethods(); i++ {
m := T.Method(i)
_, obj := lookupMethod(ityp, m.Pkg(), m.Name())
switch {
case obj == nil:
return nil, false
case !types.Identical(obj.Type(), m.Type()):
return nil, false
}
}
return nil, true
}
// A concrete type implements T if it implements all methods of T.
var sels []*types.Selection
for i := 0; i < T.NumMethods(); i++ {
m := T.Method(i)
sel := msV.Lookup(m.Pkg(), m.Name())
if sel == nil {
return nil, false
}
f, _ := sel.Obj().(*types.Func)
if f == nil {
return nil, false
}
if !types.Identical(f.Type(), m.Type()) {
return nil, false
}
sels = append(sels, sel)
}
return sels, true
}