Golang Map.Iterate方法代码示例

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
//.........这里部分代码省略.........