func accessibleMethods(t types.Type, from *types.Package) []*types.Selection {
	var methods []*types.Selection
	for _, meth := range typeutil.IntuitiveMethodSet(t, nil) {
		if isAccessibleFrom(meth.Obj(), from) {
			methods = append(methods, meth)
		}
	}
	return methods
}

func TestIntuitiveMethodSet(t *testing.T) {
	const source = `
package P
type A int
func (A) f()
func (*A) g()
`

	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "hello.go", source, 0)
	if err != nil {
		t.Fatal(err)
	}

	var conf types.Config
	pkg, err := conf.Check("P", fset, []*ast.File{f}, nil)
	if err != nil {
		t.Fatal(err)
	}
	qual := types.RelativeTo(pkg)

	for _, test := range []struct {
		expr string // type expression
		want string // intuitive method set
	}{
		{"A", "(A).f (*A).g"},
		{"*A", "(*A).f (*A).g"},
		{"error", "(error).Error"},
		{"*error", ""},
		{"struct{A}", "(struct{A}).f (*struct{A}).g"},
		{"*struct{A}", "(*struct{A}).f (*struct{A}).g"},
	} {
		tv, err := types.Eval(fset, pkg, 0, test.expr)
		if err != nil {
			t.Errorf("Eval(%s) failed: %v", test.expr, err)
		}
		var names []string
		for _, m := range typeutil.IntuitiveMethodSet(tv.Type, nil) {
			name := fmt.Sprintf("(%s).%s", types.TypeString(m.Recv(), qual), m.Obj().Name())
			names = append(names, name)
		}
		got := strings.Join(names, " ")
		if got != test.want {
			t.Errorf("IntuitiveMethodSet(%s) = %q, want %q", test.expr, got, test.want)
		}
	}
}

func main() {
	if len(os.Args) != 3 {
		log.Fatal("Usage: doc <package> <object>")
	}
	//!+part1
	pkgpath, name := os.Args[1], os.Args[2]

	// The loader loads a complete Go program from source code.
	conf := loader.Config{ParserMode: parser.ParseComments}
	conf.Import(pkgpath)
	lprog, err := conf.Load()
	if err != nil {
		log.Fatal(err) // load error
	}

	// Find the package and package-level object.
	pkg := lprog.Package(pkgpath).Pkg
	obj := pkg.Scope().Lookup(name)
	if obj == nil {
		log.Fatalf("%s.%s not found", pkg.Path(), name)
	}
	//!-part1
	//!+part2

	// Print the object and its methods (incl. location of definition).
	fmt.Println(obj)
	for _, sel := range typeutil.IntuitiveMethodSet(obj.Type(), nil) {
		fmt.Printf("%s: %s\n", lprog.Fset.Position(sel.Obj().Pos()), sel)
	}

	// Find the path from the root of the AST to the object's position.
	// Walk up to the enclosing ast.Decl for the doc comment.
	_, path, _ := lprog.PathEnclosingInterval(obj.Pos(), obj.Pos())
	for _, n := range path {
		switch n := n.(type) {
		case *ast.GenDecl:
			fmt.Println("\n", n.Doc.Text())
			return
		case *ast.FuncDecl:
			fmt.Println("\n", n.Doc.Text())
			return
		}
	}
	//!-part2
}

// WritePackage writes to buf a human-readable summary of p.
func WritePackage(buf *bytes.Buffer, p *Package) {
	fmt.Fprintf(buf, "%s:\n", p)

	var names []string
	maxname := 0
	for name := range p.Members {
		if l := len(name); l > maxname {
			maxname = l
		}
		names = append(names, name)
	}

	from := p.Pkg
	sort.Strings(names)
	for _, name := range names {
		switch mem := p.Members[name].(type) {
		case *NamedConst:
			fmt.Fprintf(buf, "  const %-*s %s = %s\n",
				maxname, name, mem.Name(), mem.Value.RelString(from))

		case *Function:
			fmt.Fprintf(buf, "  func  %-*s %s\n",
				maxname, name, relType(mem.Type(), from))

		case *Type:
			fmt.Fprintf(buf, "  type  %-*s %s\n",
				maxname, name, relType(mem.Type().Underlying(), from))
			for _, meth := range typeutil.IntuitiveMethodSet(mem.Type(), &p.Prog.MethodSets) {
				fmt.Fprintf(buf, "    %s\n", types.SelectionString(meth, types.RelativeTo(from)))
			}

		case *Global:
			fmt.Fprintf(buf, "  var   %-*s %s\n",
				maxname, name, relType(mem.Type().(*types.Pointer).Elem(), from))
		}
	}

	fmt.Fprintf(buf, "\n")
}

func (a *analysis) namedType(obj *types.TypeName, implements map[*types.Named]implementsFacts) {
	qualifier := types.RelativeTo(obj.Pkg())
	T := obj.Type().(*types.Named)
	v := &TypeInfoJSON{
		Name:    obj.Name(),
		Size:    sizes.Sizeof(T),
		Align:   sizes.Alignof(T),
		Methods: []anchorJSON{}, // (JS wants non-nil)
	}

	// addFact adds the fact "is implemented by T" (by) or
	// "implements T" (!by) to group.
	addFact := func(group *implGroupJSON, T types.Type, by bool) {
		Tobj := deref(T).(*types.Named).Obj()
		var byKind string
		if by {
			// Show underlying kind of implementing type,
			// e.g. "slice", "array", "struct".
			s := reflect.TypeOf(T.Underlying()).String()
			byKind = strings.ToLower(strings.TrimPrefix(s, "*types."))
		}
		group.Facts = append(group.Facts, implFactJSON{
			ByKind: byKind,
			Other: anchorJSON{
				Href: a.posURL(Tobj.Pos(), len(Tobj.Name())),
				Text: types.TypeString(T, qualifier),
			},
		})
	}

	// IMPLEMENTS
	if r, ok := implements[T]; ok {
		if isInterface(T) {
			// "T is implemented by <conc>" ...
			// "T is implemented by <iface>"...
			// "T implements        <iface>"...
			group := implGroupJSON{
				Descr: types.TypeString(T, qualifier),
			}
			// Show concrete types first; use two passes.
			for _, sub := range r.to {
				if !isInterface(sub) {
					addFact(&group, sub, true)
				}
			}
			for _, sub := range r.to {
				if isInterface(sub) {
					addFact(&group, sub, true)
				}
			}
			for _, super := range r.from {
				addFact(&group, super, false)
			}
			v.ImplGroups = append(v.ImplGroups, group)
		} else {
			// T is concrete.
			if r.from != nil {
				// "T implements <iface>"...
				group := implGroupJSON{
					Descr: types.TypeString(T, qualifier),
				}
				for _, super := range r.from {
					addFact(&group, super, false)
				}
				v.ImplGroups = append(v.ImplGroups, group)
			}
			if r.fromPtr != nil {
				// "*C implements <iface>"...
				group := implGroupJSON{
					Descr: "*" + types.TypeString(T, qualifier),
				}
				for _, psuper := range r.fromPtr {
					addFact(&group, psuper, false)
				}
				v.ImplGroups = append(v.ImplGroups, group)
			}
		}
	}

	// METHOD SETS
	for _, sel := range typeutil.IntuitiveMethodSet(T, &a.prog.MethodSets) {
		meth := sel.Obj().(*types.Func)
		pos := meth.Pos() // may be 0 for error.Error
		v.Methods = append(v.Methods, anchorJSON{
			Href: a.posURL(pos, len(meth.Name())),
			Text: types.SelectionString(sel, qualifier),
		})
	}

	// Since there can be many specs per decl, we
	// can't attach the link to the keyword 'type'
	// (as we do with 'func'); we use the Ident.
	fi, offset := a.fileAndOffset(obj.Pos())
	fi.addLink(aLink{
		start:   offset,
		end:     offset + len(obj.Name()),
		title:   fmt.Sprintf("type info for %s", obj.Name()),
		onclick: fmt.Sprintf("onClickTypeInfo(%d)", fi.addData(v)),
	})

//.........这里部分代码省略.........