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
}
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, "")
}
}