func (p *importer) obj(tag int) {
	switch tag {
	case constTag:
		pos := p.pos()
		pkg, name := p.qualifiedName()
		typ := p.typ(nil)
		val := p.value()
		p.declare(types.NewConst(pos, pkg, name, typ, val))

	case typeTag:
		_ = p.typ(nil)

	case varTag:
		pos := p.pos()
		pkg, name := p.qualifiedName()
		typ := p.typ(nil)
		p.declare(types.NewVar(pos, pkg, name, typ))

	case funcTag:
		pos := p.pos()
		pkg, name := p.qualifiedName()
		params, isddd := p.paramList()
		result, _ := p.paramList()
		sig := types.NewSignature(nil, params, result, isddd)
		p.declare(types.NewFunc(pos, pkg, name, sig))

	default:
		panic(fmt.Sprintf("unexpected object tag %d", tag))
	}
}

// Const = Name [Type] "=" ConstValue .
func (p *parser) parseConst(pkg *types.Package) *types.Const {
	name := p.parseName()
	var typ types.Type
	if p.tok == '<' {
		typ = p.parseType(pkg)
	}
	p.expect('=')
	val, vtyp := p.parseConstValue()
	if typ == nil {
		typ = vtyp
	}
	return types.NewConst(token.NoPos, pkg, name, typ, val)
}

func (p *importer) obj(tag int) {
	switch tag {
	case constTag:
		pos := p.pos()
		pkg, name := p.qualifiedName()
		typ := p.typ(nil)
		val := p.value()
		p.declare(types.NewConst(pos, pkg, name, typ, val))

	case typeTag:
		p.typ(nil)

	case varTag:
		pos := p.pos()
		pkg, name := p.qualifiedName()
		typ := p.typ(nil)
		p.declare(types.NewVar(pos, pkg, name, typ))

	case funcTag:
		pos := p.pos()
		pkg, name := p.qualifiedName()
		params, isddd := p.paramList()
		result, _ := p.paramList()
		sig := types.NewSignature(nil, params, result, isddd)
		p.declare(types.NewFunc(pos, pkg, name, sig))

	case aliasTag:
		pos := p.pos()
		name := p.string()
		var orig types.Object
		if pkg, name := p.qualifiedName(); pkg != nil {
			orig = pkg.Scope().Lookup(name)
		}
		// Alias-related code. Keep for now.
		_ = pos
		_ = name
		_ = orig
		// p.declare(types.NewAlias(pos, p.pkgList[0], name, orig))

	default:
		errorf("unexpected object tag %d", tag)
	}
}

func (p *importer) obj(pkg *types.Package) {
	var obj types.Object
	switch tag := p.int(); tag {
	case constTag:
		obj = types.NewConst(token.NoPos, pkg, p.string(), p.typ(), p.value())
	case typeTag:
		// type object is added to scope via respective named type
		_ = p.typ().(*types.Named)
		return
	case varTag:
		obj = types.NewVar(token.NoPos, pkg, p.string(), p.typ())
	case funcTag:
		obj = types.NewFunc(token.NoPos, pkg, p.string(), p.typ().(*types.Signature))
	default:
		panic(fmt.Sprintf("unexpected object tag %d", tag))
	}

	if alt := pkg.Scope().Insert(obj); alt != nil {
		panic(fmt.Sprintf("%s already declared", alt.Name()))
	}
}

// BImportData imports a package from the serialized package data
// and returns the number of bytes consumed and a reference to the package.
// If data is obviously malformed, an error is returned but in
// general it is not recommended to call BImportData on untrusted data.
func BImportData(imports map[string]*types.Package, data []byte, path string) (int, *types.Package, error) {
	p := importer{
		imports: imports,
		data:    data,
	}
	p.buf = p.bufarray[:]

	// read low-level encoding format
	switch format := p.byte(); format {
	case 'c':
		// compact format - nothing to do
	case 'd':
		p.debugFormat = true
	default:
		return p.read, nil, fmt.Errorf("invalid encoding format in export data: got %q; want 'c' or 'd'", format)
	}

	// --- generic export data ---

	if v := p.string(); v != "v0" {
		return p.read, nil, fmt.Errorf("unknown version: %s", v)
	}

	// populate typList with predeclared "known" types
	p.typList = append(p.typList, predeclared...)

	// read package data
	// TODO(gri) clean this up
	i := p.tagOrIndex()
	if i != packageTag {
		panic(fmt.Sprintf("package tag expected, got %d", i))
	}
	name := p.string()
	if s := p.string(); s != "" {
		panic(fmt.Sprintf("empty path expected, got %s", s))
	}
	pkg := p.imports[path]
	if pkg == nil {
		pkg = types.NewPackage(path, name)
		p.imports[path] = pkg
	}
	p.pkgList = append(p.pkgList, pkg)

	if debug && p.pkgList[0] != pkg {
		panic("imported packaged not found in pkgList[0]")
	}

	// read compiler-specific flags
	p.string() // discard

	// read consts
	for i := p.int(); i > 0; i-- {
		name := p.string()
		typ := p.typ(nil)
		val := p.value()
		p.declare(types.NewConst(token.NoPos, pkg, name, typ, val))
	}

	// read vars
	for i := p.int(); i > 0; i-- {
		name := p.string()
		typ := p.typ(nil)
		p.declare(types.NewVar(token.NoPos, pkg, name, typ))
	}

	// read funcs
	for i := p.int(); i > 0; i-- {
		name := p.string()
		sig := p.typ(nil).(*types.Signature)
		p.int() // read and discard index of inlined function body
		p.declare(types.NewFunc(token.NoPos, pkg, name, sig))
	}

	// read types
	for i := p.int(); i > 0; i-- {
		// name is parsed as part of named type and the
		// type object is added to scope via respective
		// named type
		_ = p.typ(nil).(*types.Named)
	}

	// ignore compiler-specific import data

	// complete interfaces
	for _, typ := range p.typList {
		if it, ok := typ.(*types.Interface); ok {
			it.Complete()
		}
	}

	// record all referenced packages as imports
	list := append(([]*types.Package)(nil), p.pkgList[1:]...)
	sort.Sort(byPath(list))
	pkg.SetImports(list)

	// package was imported completely and without errors
//.........这里部分代码省略.........

// ConstDecl   = "const" ExportedName [ Type ] "=" Literal .
// Literal     = bool_lit | int_lit | float_lit | complex_lit | rune_lit | string_lit .
// bool_lit    = "true" | "false" .
// complex_lit = "(" float_lit "+" float_lit "i" ")" .
// rune_lit    = "(" int_lit "+" int_lit ")" .
// string_lit  = `"` { unicode_char } `"` .
//
func (p *parser) parseConstDecl() {
	p.expectKeyword("const")
	pkg, name := p.parseExportedName()

	var typ0 types.Type
	if p.tok != '=' {
		// constant types are never structured - no need for parent type
		typ0 = p.parseType(nil)
	}

	p.expect('=')
	var typ types.Type
	var val exact.Value
	switch p.tok {
	case scanner.Ident:
		// bool_lit
		if p.lit != "true" && p.lit != "false" {
			p.error("expected true or false")
		}
		typ = types.Typ[types.UntypedBool]
		val = exact.MakeBool(p.lit == "true")
		p.next()

	case '-', scanner.Int:
		// int_lit
		typ, val = p.parseNumber()

	case '(':
		// complex_lit or rune_lit
		p.next()
		if p.tok == scanner.Char {
			p.next()
			p.expect('+')
			typ = types.Typ[types.UntypedRune]
			_, val = p.parseNumber()
			p.expect(')')
			break
		}
		_, re := p.parseNumber()
		p.expect('+')
		_, im := p.parseNumber()
		p.expectKeyword("i")
		p.expect(')')
		typ = types.Typ[types.UntypedComplex]
		val = exact.BinaryOp(re, token.ADD, exact.MakeImag(im))

	case scanner.Char:
		// rune_lit
		typ = types.Typ[types.UntypedRune]
		val = exact.MakeFromLiteral(p.lit, token.CHAR, 0)
		p.next()

	case scanner.String:
		// string_lit
		typ = types.Typ[types.UntypedString]
		val = exact.MakeFromLiteral(p.lit, token.STRING, 0)
		p.next()

	default:
		p.errorf("expected literal got %s", scanner.TokenString(p.tok))
	}

	if typ0 == nil {
		typ0 = typ
	}

	pkg.Scope().Insert(types.NewConst(token.NoPos, pkg, name, typ0, val))
}

// CreateTestMainPackage creates and returns a synthetic "main"
// package that runs all the tests of the supplied packages, similar
// to the one that would be created by the 'go test' tool.
//
// It returns nil if the program contains no tests.
//
func (prog *Program) CreateTestMainPackage(pkgs ...*Package) *Package {
	pkgs, tests, benchmarks, examples := FindTests(pkgs)
	if len(pkgs) == 0 {
		return nil
	}

	testmain := &Package{
		Prog:    prog,
		Members: make(map[string]Member),
		values:  make(map[types.Object]Value),
		Pkg:     types.NewPackage("test$main", "main"),
	}

	// Build package's init function.
	init := &Function{
		name:      "init",
		Signature: new(types.Signature),
		Synthetic: "package initializer",
		Pkg:       testmain,
		Prog:      prog,
	}
	init.startBody()

	if testMainStartBodyHook != nil {
		testMainStartBodyHook(init)
	}

	// Initialize packages to test.
	var pkgpaths []string
	for _, pkg := range pkgs {
		var v Call
		v.Call.Value = pkg.init
		v.setType(types.NewTuple())
		init.emit(&v)

		pkgpaths = append(pkgpaths, pkg.Pkg.Path())
	}
	sort.Strings(pkgpaths)
	init.emit(new(Return))
	init.finishBody()
	testmain.init = init
	testmain.Pkg.MarkComplete()
	testmain.Members[init.name] = init

	// For debugging convenience, define an unexported const
	// that enumerates the packages.
	packagesConst := types.NewConst(token.NoPos, testmain.Pkg, "packages", tString,
		exact.MakeString(strings.Join(pkgpaths, " ")))
	memberFromObject(testmain, packagesConst, nil)

	// Create main *types.Func and *ssa.Function
	mainFunc := types.NewFunc(token.NoPos, testmain.Pkg, "main", new(types.Signature))
	memberFromObject(testmain, mainFunc, nil)
	main := testmain.Func("main")
	main.Synthetic = "test main function"

	main.startBody()

	if testMainStartBodyHook != nil {
		testMainStartBodyHook(main)
	}

	if testingPkg := prog.ImportedPackage("testing"); testingPkg != nil {
		testingMain := testingPkg.Func("Main")
		testingMainParams := testingMain.Signature.Params()

		// The generated code is as if compiled from this:
		//
		// func main() {
		//      match      := func(_, _ string) (bool, error) { return true, nil }
		//      tests      := []testing.InternalTest{{"TestFoo", TestFoo}, ...}
		//      benchmarks := []testing.InternalBenchmark{...}
		//      examples   := []testing.InternalExample{...}
		// 	testing.Main(match, tests, benchmarks, examples)
		// }

		matcher := &Function{
			name:      "matcher",
			Signature: testingMainParams.At(0).Type().(*types.Signature),
			Synthetic: "test matcher predicate",
			parent:    main,
			Pkg:       testmain,
			Prog:      prog,
		}
		main.AnonFuncs = append(main.AnonFuncs, matcher)
		matcher.startBody()
		matcher.emit(&Return{Results: []Value{vTrue, nilConst(types.Universe.Lookup("error").Type())}})
		matcher.finishBody()

		// Emit call: testing.Main(matcher, tests, benchmarks, examples).
		var c Call
		c.Call.Value = testingMain
		c.Call.Args = []Value{
			matcher,
//.........这里部分代码省略.........