// flatten returns a list of directly contained fields in the preorder
// traversal of the type tree of t. The resulting elements are all
// scalars (basic types or pointerlike types), except for struct/array
// "identity" nodes, whose type is that of the aggregate.
//
// reflect.Value is considered pointerlike, similar to interface{}.
//
// Callers must not mutate the result.
//
func (a *analysis) flatten(t types.Type) []*fieldInfo {
fl, ok := a.flattenMemo[t]
if !ok {
switch t := t.(type) {
case *types.Named:
u := t.Underlying()
if isInterface(u) {
// Debuggability hack: don't remove
// the named type from interfaces as
// they're very verbose.
fl = append(fl, &fieldInfo{typ: t})
} else {
fl = a.flatten(u)
}
case *types.Basic,
*types.Signature,
*types.Chan,
*types.Map,
*types.Interface,
*types.Slice,
*types.Pointer:
fl = append(fl, &fieldInfo{typ: t})
case *types.Array:
fl = append(fl, &fieldInfo{typ: t}) // identity node
for _, fi := range a.flatten(t.Elem()) {
fl = append(fl, &fieldInfo{typ: fi.typ, op: true, tail: fi})
}
case *types.Struct:
fl = append(fl, &fieldInfo{typ: t}) // identity node
for i, n := 0, t.NumFields(); i < n; i++ {
f := t.Field(i)
for _, fi := range a.flatten(f.Type()) {
fl = append(fl, &fieldInfo{typ: fi.typ, op: f, tail: fi})
}
}
case *types.Tuple:
// No identity node: tuples are never address-taken.
n := t.Len()
if n == 1 {
// Don't add a fieldInfo link for singletons,
// e.g. in params/results.
fl = append(fl, a.flatten(t.At(0).Type())...)
} else {
for i := 0; i < n; i++ {
f := t.At(i)
for _, fi := range a.flatten(f.Type()) {
fl = append(fl, &fieldInfo{typ: fi.typ, op: i, tail: fi})
}
}
}
default:
panic(t)
}
a.flattenMemo[t] = fl
}
return fl
}
// zero returns a new "zero" value of the specified type.
func zero(t types.Type) value {
switch t := t.(type) {
case *types.Basic:
if t.Kind() == types.UntypedNil {
panic("untyped nil has no zero value")
}
if t.Info()&types.IsUntyped != 0 {
// TODO(adonovan): make it an invariant that
// this is unreachable. Currently some
// constants have 'untyped' types when they
// should be defaulted by the typechecker.
t = ssa.DefaultType(t).(*types.Basic)
}
switch t.Kind() {
case types.Bool:
return false
case types.Int:
return int(0)
case types.Int8:
return int8(0)
case types.Int16:
return int16(0)
case types.Int32:
return int32(0)
case types.Int64:
return int64(0)
case types.Uint:
return uint(0)
case types.Uint8:
return uint8(0)
case types.Uint16:
return uint16(0)
case types.Uint32:
return uint32(0)
case types.Uint64:
return uint64(0)
case types.Uintptr:
return uintptr(0)
case types.Float32:
return float32(0)
case types.Float64:
return float64(0)
case types.Complex64:
return complex64(0)
case types.Complex128:
return complex128(0)
case types.String:
return ""
case types.UnsafePointer:
return unsafe.Pointer(nil)
default:
panic(fmt.Sprint("zero for unexpected type:", t))
}
case *types.Pointer:
return (*value)(nil)
case *types.Array:
a := make(array, t.Len())
for i := range a {
a[i] = zero(t.Elem())
}
return a
case *types.Named:
return zero(t.Underlying())
case *types.Interface:
return iface{} // nil type, methodset and value
case *types.Slice:
return []value(nil)
case *types.Struct:
s := make(structure, t.NumFields())
for i := range s {
s[i] = zero(t.Field(i).Type())
}
return s
case *types.Tuple:
if t.Len() == 1 {
return zero(t.At(0).Type())
}
s := make(tuple, t.Len())
for i := range s {
s[i] = zero(t.At(i).Type())
}
return s
case *types.Chan:
return chan value(nil)
case *types.Map:
if usesBuiltinMap(t.Key()) {
return map[value]value(nil)
}
return (*hashmap)(nil)
case *types.Signature:
return (*ssa.Function)(nil)
}
panic(fmt.Sprint("zero: unexpected ", t))
}
// addRuntimeType is called for each concrete type that can be the
// dynamic type of some interface or reflect.Value.
// Adapted from needMethods in go/ssa/builder.go
//
func (r *rta) addRuntimeType(T types.Type, skip bool) {
if prev, ok := r.result.RuntimeTypes.At(T).(bool); ok {
if skip && !prev {
r.result.RuntimeTypes.Set(T, skip)
}
return
}
r.result.RuntimeTypes.Set(T, skip)
mset := r.prog.MethodSets.MethodSet(T)
if _, ok := T.Underlying().(*types.Interface); !ok {
// T is a new concrete type.
for i, n := 0, mset.Len(); i < n; i++ {
sel := mset.At(i)
m := sel.Obj()
if m.Exported() {
// Exported methods are always potentially callable via reflection.
r.addReachable(r.prog.Method(sel), true)
}
}
// Add callgraph edge for each existing dynamic
// "invoke"-mode call via that interface.
for _, I := range r.interfaces(T) {
sites, _ := r.invokeSites.At(I).([]ssa.CallInstruction)
for _, site := range sites {
r.addInvokeEdge(site, T)
}
}
}
// Precondition: T is not a method signature (*Signature with Recv()!=nil).
// Recursive case: skip => don't call makeMethods(T).
// Each package maintains its own set of types it has visited.
var n *types.Named
switch T := T.(type) {
case *types.Named:
n = T
case *types.Pointer:
n, _ = T.Elem().(*types.Named)
}
if n != nil {
owner := n.Obj().Pkg()
if owner == nil {
return // built-in error type
}
}
// Recursion over signatures of each exported method.
for i := 0; i < mset.Len(); i++ {
if mset.At(i).Obj().Exported() {
sig := mset.At(i).Type().(*types.Signature)
r.addRuntimeType(sig.Params(), true) // skip the Tuple itself
r.addRuntimeType(sig.Results(), true) // skip the Tuple itself
}
}
switch t := T.(type) {
case *types.Basic:
// nop
case *types.Interface:
// nop---handled by recursion over method set.
case *types.Pointer:
r.addRuntimeType(t.Elem(), false)
case *types.Slice:
r.addRuntimeType(t.Elem(), false)
case *types.Chan:
r.addRuntimeType(t.Elem(), false)
case *types.Map:
r.addRuntimeType(t.Key(), false)
r.addRuntimeType(t.Elem(), false)
case *types.Signature:
if t.Recv() != nil {
panic(fmt.Sprintf("Signature %s has Recv %s", t, t.Recv()))
}
r.addRuntimeType(t.Params(), true) // skip the Tuple itself
r.addRuntimeType(t.Results(), true) // skip the Tuple itself
case *types.Named:
// A pointer-to-named type can be derived from a named
// type via reflection. It may have methods too.
r.addRuntimeType(types.NewPointer(T), false)
// Consider 'type T struct{S}' where S has methods.
// Reflection provides no way to get from T to struct{S},
// only to S, so the method set of struct{S} is unwanted,
// so set 'skip' flag during recursion.
r.addRuntimeType(t.Underlying(), true)
case *types.Array:
r.addRuntimeType(t.Elem(), false)
case *types.Struct:
for i, n := 0, t.NumFields(); i < n; i++ {
r.addRuntimeType(t.Field(i).Type(), false)
}
case *types.Tuple:
for i, n := 0, t.Len(); i < n; i++ {
r.addRuntimeType(t.At(i).Type(), false)
}
default:
panic(T)
}
}
// hashFor computes the hash of t.
func (h Hasher) hashFor(t types.Type) uint32 {
// See Identical for rationale.
switch t := t.(type) {
case *types.Basic:
return uint32(t.Kind())
case *types.Array:
return 9043 + 2*uint32(t.Len()) + 3*h.Hash(t.Elem())
case *types.Slice:
return 9049 + 2*h.Hash(t.Elem())
case *types.Struct:
var hash uint32 = 9059
for i, n := 0, t.NumFields(); i < n; i++ {
f := t.Field(i)
if f.Anonymous() {
hash += 8861
}
hash += hashString(t.Tag(i))
hash += hashString(f.Name()) // (ignore f.Pkg)
hash += h.Hash(f.Type())
}
return hash
case *types.Pointer:
return 9067 + 2*h.Hash(t.Elem())
case *types.Signature:
var hash uint32 = 9091
if t.Variadic() {
hash *= 8863
}
return hash + 3*h.hashTuple(t.Params()) + 5*h.hashTuple(t.Results())
case *types.Interface:
var hash uint32 = 9103
for i, n := 0, t.NumMethods(); i < n; i++ {
// See go/types.identicalMethods for rationale.
// Method order is not significant.
// Ignore m.Pkg().
m := t.Method(i)
hash += 3*hashString(m.Name()) + 5*h.Hash(m.Type())
}
return hash
case *types.Map:
return 9109 + 2*h.Hash(t.Key()) + 3*h.Hash(t.Elem())
case *types.Chan:
return 9127 + 2*uint32(t.Dir()) + 3*h.Hash(t.Elem())
case *types.Named:
// Not safe with a copying GC; objects may move.
return uint32(reflect.ValueOf(t.Obj()).Pointer())
case *types.Tuple:
return h.hashTuple(t)
}
panic(t)
}