func ExampleMap() {
const source = `package P
var X []string
var Y []string
const p, q = 1.0, 2.0
func f(offset int32) (value byte, ok bool)
func g(rune) (uint8, bool)
`
// Parse and type-check the package.
fset := token.NewFileSet()
f, err := parser.ParseFile(fset, "P.go", source, 0)
if err != nil {
panic(err)
}
pkg, err := new(types.Config).Check("P", fset, []*ast.File{f}, nil)
if err != nil {
panic(err)
}
scope := pkg.Scope()
// Group names of package-level objects by their type.
var namesByType typeutil.Map // value is []string
for _, name := range scope.Names() {
T := scope.Lookup(name).Type()
names, _ := namesByType.At(T).([]string)
names = append(names, name)
namesByType.Set(T, names)
}
// Format, sort, and print the map entries.
var lines []string
namesByType.Iterate(func(T types.Type, names interface{}) {
lines = append(lines, fmt.Sprintf("%s %s", names, T))
})
sort.Strings(lines)
for _, line := range lines {
fmt.Println(line)
}
// Output:
// [X Y] []string
// [f g] func(offset int32) (value byte, ok bool)
// [p q] untyped float
}
// If this PointsToSet came from a Pointer of interface kind
// or a reflect.Value, DynamicTypes returns the set of dynamic
// types that it may contain. (For an interface, they will
// always be concrete types.)
//
// The result is a mapping whose keys are the dynamic types to which
// it may point. For each pointer-like key type, the corresponding
// map value is the PointsToSet for pointers of that type.
//
// The result is empty unless CanHaveDynamicTypes(T).
//
func (s PointsToSet) DynamicTypes() *typeutil.Map {
var tmap typeutil.Map
tmap.SetHasher(s.a.hasher)
if s.pts != nil {
var space [50]int
for _, x := range s.pts.AppendTo(space[:0]) {
ifaceObjId := nodeid(x)
if !s.a.isTaggedObject(ifaceObjId) {
continue // !CanHaveDynamicTypes(tDyn)
}
tDyn, v, indirect := s.a.taggedValue(ifaceObjId)
if indirect {
panic("indirect tagged object") // implement later
}
pts, ok := tmap.At(tDyn).(PointsToSet)
if !ok {
pts = PointsToSet{s.a, new(nodeset)}
tmap.Set(tDyn, pts)
}
pts.pts.addAll(&s.a.nodes[v].solve.pts)
}
}
return &tmap
}
func checkTypesExpectation(e *expectation, pts pointer.PointsToSet, typ types.Type) bool {
var expected typeutil.Map
var surplus typeutil.Map
exact := true
for _, g := range e.types {
if g == types.Typ[types.Invalid] {
exact = false
continue
}
expected.Set(g, struct{}{})
}
if !pointer.CanHaveDynamicTypes(typ) {
e.errorf("@types expectation requires an interface- or reflect.Value-typed operand, got %s", typ)
return false
}
// Find the set of types that the probe's
// argument (x in print(x)) may contain.
for _, T := range pts.DynamicTypes().Keys() {
if expected.At(T) != nil {
expected.Delete(T)
} else if exact {
surplus.Set(T, struct{}{})
}
}
// Report set difference:
ok := true
if expected.Len() > 0 {
ok = false
e.errorf("interface cannot contain these types: %s", expected.KeysString())
}
if surplus.Len() > 0 {
ok = false
e.errorf("interface may additionally contain these types: %s", surplus.KeysString())
}
return ok
}
// CallGraph computes the call graph of the specified program using the
// Class Hierarchy Analysis algorithm.
//
func CallGraph(prog *ssa.Program) *callgraph.Graph {
cg := callgraph.New(nil) // TODO(adonovan) eliminate concept of rooted callgraph
allFuncs := ssautil.AllFunctions(prog)
// funcsBySig contains all functions, keyed by signature. It is
// the effective set of address-taken functions used to resolve
// a dynamic call of a particular signature.
var funcsBySig typeutil.Map // value is []*ssa.Function
// methodsByName contains all methods,
// grouped by name for efficient lookup.
methodsByName := make(map[string][]*ssa.Function)
// methodsMemo records, for every abstract method call call I.f on
// interface type I, the set of concrete methods C.f of all
// types C that satisfy interface I.
methodsMemo := make(map[*types.Func][]*ssa.Function)
lookupMethods := func(m *types.Func) []*ssa.Function {
methods, ok := methodsMemo[m]
if !ok {
I := m.Type().(*types.Signature).Recv().Type().Underlying().(*types.Interface)
for _, f := range methodsByName[m.Name()] {
C := f.Signature.Recv().Type() // named or *named
if types.Implements(C, I) {
methods = append(methods, f)
}
}
methodsMemo[m] = methods
}
return methods
}
for f := range allFuncs {
if f.Signature.Recv() == nil {
// Package initializers can never be address-taken.
if f.Name() == "init" && f.Synthetic == "package initializer" {
continue
}
funcs, _ := funcsBySig.At(f.Signature).([]*ssa.Function)
funcs = append(funcs, f)
funcsBySig.Set(f.Signature, funcs)
} else {
methodsByName[f.Name()] = append(methodsByName[f.Name()], f)
}
}
addEdge := func(fnode *callgraph.Node, site ssa.CallInstruction, g *ssa.Function) {
gnode := cg.CreateNode(g)
callgraph.AddEdge(fnode, site, gnode)
}
addEdges := func(fnode *callgraph.Node, site ssa.CallInstruction, callees []*ssa.Function) {
// Because every call to a highly polymorphic and
// frequently used abstract method such as
// (io.Writer).Write is assumed to call every concrete
// Write method in the program, the call graph can
// contain a lot of duplication.
//
// TODO(adonovan): opt: consider factoring the callgraph
// API so that the Callers component of each edge is a
// slice of nodes, not a singleton.
for _, g := range callees {
addEdge(fnode, site, g)
}
}
for f := range allFuncs {
fnode := cg.CreateNode(f)
for _, b := range f.Blocks {
for _, instr := range b.Instrs {
if site, ok := instr.(ssa.CallInstruction); ok {
call := site.Common()
if call.IsInvoke() {
addEdges(fnode, site, lookupMethods(call.Method))
} else if g := call.StaticCallee(); g != nil {
addEdge(fnode, site, g)
} else if _, ok := call.Value.(*ssa.Builtin); !ok {
callees, _ := funcsBySig.At(call.Signature()).([]*ssa.Function)
addEdges(fnode, site, callees)
}
}
}
}
}
return cg
}
func TestMap(t *testing.T) {
var tmap *typeutil.Map
// All methods but Set are safe on on (*T)(nil).
tmap.Len()
tmap.At(tPStr1)
tmap.Delete(tPStr1)
tmap.KeysString()
tmap.String()
tmap = new(typeutil.Map)
// Length of empty map.
if l := tmap.Len(); l != 0 {
t.Errorf("Len() on empty Map: got %d, want 0", l)
}
// At of missing key.
if v := tmap.At(tPStr1); v != nil {
t.Errorf("At() on empty Map: got %v, want nil", v)
}
// Deletion of missing key.
if tmap.Delete(tPStr1) {
t.Errorf("Delete() on empty Map: got true, want false")
}
// Set of new key.
if prev := tmap.Set(tPStr1, "*string"); prev != nil {
t.Errorf("Set() on empty Map returned non-nil previous value %s", prev)
}
// Now: {*string: "*string"}
// Length of non-empty map.
if l := tmap.Len(); l != 1 {
t.Errorf("Len(): got %d, want 1", l)
}
// At via insertion key.
if v := tmap.At(tPStr1); v != "*string" {
t.Errorf("At(): got %q, want \"*string\"", v)
}
// At via equal key.
if v := tmap.At(tPStr2); v != "*string" {
t.Errorf("At(): got %q, want \"*string\"", v)
}
// Iteration over sole entry.
tmap.Iterate(func(key types.Type, value interface{}) {
if key != tPStr1 {
t.Errorf("Iterate: key: got %s, want %s", key, tPStr1)
}
if want := "*string"; value != want {
t.Errorf("Iterate: value: got %s, want %s", value, want)
}
})
// Setion with key equal to present one.
if prev := tmap.Set(tPStr2, "*string again"); prev != "*string" {
t.Errorf("Set() previous value: got %s, want \"*string\"", prev)
}
// Setion of another association.
if prev := tmap.Set(tChanInt1, "<-chan int"); prev != nil {
t.Errorf("Set() previous value: got %s, want nil", prev)
}
// Now: {*string: "*string again", <-chan int: "<-chan int"}
want1 := "{*string: \"*string again\", <-chan int: \"<-chan int\"}"
want2 := "{<-chan int: \"<-chan int\", *string: \"*string again\"}"
if s := tmap.String(); s != want1 && s != want2 {
t.Errorf("String(): got %s, want %s", s, want1)
}
want1 = "{*string, <-chan int}"
want2 = "{<-chan int, *string}"
if s := tmap.KeysString(); s != want1 && s != want2 {
t.Errorf("KeysString(): got %s, want %s", s, want1)
}
// Keys().
I := types.Identical
switch k := tmap.Keys(); {
case I(k[0], tChanInt1) && I(k[1], tPStr1): // ok
case I(k[1], tChanInt1) && I(k[0], tPStr1): // ok
default:
t.Errorf("Keys(): got %v, want %s", k, want2)
}
if l := tmap.Len(); l != 2 {
t.Errorf("Len(): got %d, want 1", l)
}
// At via original key.
if v := tmap.At(tPStr1); v != "*string again" {
t.Errorf("At(): got %q, want \"*string again\"", v)
}
hamming := 1
tmap.Iterate(func(key types.Type, value interface{}) {
switch {
case I(key, tChanInt1):
hamming *= 2 // ok
case I(key, tPStr1):
hamming *= 3 // ok
}
})
if hamming != 6 {
t.Errorf("Iterate: hamming: got %d, want %d", hamming, 6)
}
if v := tmap.At(tChanInt2); v != "<-chan int" {
t.Errorf("At(): got %q, want \"<-chan int\"", v)
}
// Deletion with key equal to present one.
if !tmap.Delete(tChanInt2) {
t.Errorf("Delete() of existing key: got false, want true")
}
// Now: {*string: "*string again"}
if l := tmap.Len(); l != 1 {
t.Errorf("Len(): got %d, want 1", l)
}
// Deletion again.
if !tmap.Delete(tPStr2) {
t.Errorf("Delete() of existing key: got false, want true")
}
// Now: {}
if l := tmap.Len(); l != 0 {
t.Errorf("Len(): got %d, want %d", l, 0)
}
if s := tmap.String(); s != "{}" {
t.Errorf("Len(): got %q, want %q", s, "")
}
}