func hasError(sig *types.Signature) bool {
	res := sig.Results()
	if res == nil || res.Len() <= 0 {
		return false
	}

	nerr := 0
	for i := 0; i < res.Len(); i++ {
		ret := res.At(i)
		if isErrorType(ret.Type()) {
			nerr++
		}
	}

	switch {
	case nerr == 0:
		return false
	case nerr == 1:
		return true
	default:
		panic(fmt.Errorf(
			"gopy: invalid number of comma-errors (%d)",
			nerr,
		))
	}

	return false
}

// FuncHasQuery returns the offset of the string parameter named "query", or
// none if no such parameter exists.
func FuncHasQuery(s *types.Signature) (offset int, ok bool) {
	params := s.Params()
	for i := 0; i < params.Len(); i++ {
		v := params.At(i)
		if v.Name() == "query" && v.Type() == stringType {
			return i, true
		}
	}
	return 0, false
}

// formatIndex returns the index of the format string parameter within
// a signature. If it cannot find any format string parameter, it
// returns -1.
func formatIndex(sig *types.Signature) int {
	if sig == nil {
		return -1
	}
	idx := -1
	for i := 0; i < sig.Params().Len(); i++ {
		p := sig.Params().At(i)
		if typ, ok := p.Type().(*types.Basic); ok && typ.Kind() == types.String {
			idx = i
		}
	}
	return idx
}

// writeSignature writes to buf the signature sig in declaration syntax.
func writeSignature(buf *bytes.Buffer, from *types.Package, name string, sig *types.Signature, params []*Parameter) {
	buf.WriteString("func ")
	if recv := sig.Recv(); recv != nil {
		buf.WriteString("(")
		if n := params[0].Name(); n != "" {
			buf.WriteString(n)
			buf.WriteString(" ")
		}
		types.WriteType(buf, params[0].Type(), types.RelativeTo(from))
		buf.WriteString(") ")
	}
	buf.WriteString(name)
	types.WriteSignature(buf, sig, types.RelativeTo(from))
}

func (p *exporter) signature(sig *types.Signature) {
	// We need the receiver information (T vs *T)
	// for methods associated with named types.
	// We do not record interface receiver types in the
	// export data because 1) the importer can derive them
	// from the interface type and 2) they create cycles
	// in the type graph.
	if recv := sig.Recv(); recv != nil {
		if _, ok := recv.Type().Underlying().(*types.Interface); !ok {
			// 1-element tuple
			p.int(1)
			p.param(recv)
		} else {
			// 0-element tuple
			p.int(0)
		}
	} else {
		// 0-element tuple
		p.int(0)
	}
	p.tuple(sig.Params())
	p.tuple(sig.Results())
	if sig.Variadic() {
		p.int(1)
	} else {
		p.int(0)
	}
}

func isImplementable(sig *types.Signature) bool {
	params := sig.Params()
	for i := 0; i < params.Len(); i++ {
		if !isExported(params.At(i).Type()) {
			return false
		}
	}
	res := sig.Results()
	for i := 0; i < res.Len(); i++ {
		if !isExported(res.At(i).Type()) {
			return false
		}
	}
	return true
}

func (c *funcContext) translateCall(e *ast.CallExpr, sig *types.Signature, fun *expression) *expression {
	args := c.translateArgs(sig, e.Args, e.Ellipsis.IsValid(), false)
	if c.Blocking[e] {
		resumeCase := c.caseCounter
		c.caseCounter++
		returnVar := "$r"
		if sig.Results().Len() != 0 {
			returnVar = c.newVariable("_r")
		}
		c.Printf("%[1]s = %[2]s(%[3]s); /* */ $s = %[4]d; case %[4]d: if($c) { $c = false; %[1]s = %[1]s.$blk(); } if (%[1]s && %[1]s.$blk !== undefined) { break s; }", returnVar, fun, strings.Join(args, ", "), resumeCase)
		if sig.Results().Len() != 0 {
			return c.formatExpr("%s", returnVar)
		}
		return c.formatExpr("")
	}
	return c.formatExpr("%s(%s)", fun, strings.Join(args, ", "))
}

func (c *funcContext) translateArgs(sig *types.Signature, argExprs []ast.Expr, ellipsis, clone bool) []string {
	if len(argExprs) == 1 {
		if tuple, isTuple := c.p.TypeOf(argExprs[0]).(*types.Tuple); isTuple {
			tupleVar := c.newVariable("_tuple")
			c.Printf("%s = %s;", tupleVar, c.translateExpr(argExprs[0]))
			argExprs = make([]ast.Expr, tuple.Len())
			for i := range argExprs {
				argExprs[i] = c.newIdent(c.formatExpr("%s[%d]", tupleVar, i).String(), tuple.At(i).Type())
			}
		}
	}

	paramsLen := sig.Params().Len()

	var varargType *types.Slice
	if sig.Variadic() && !ellipsis {
		varargType = sig.Params().At(paramsLen - 1).Type().(*types.Slice)
	}

	preserveOrder := false
	for i := 1; i < len(argExprs); i++ {
		preserveOrder = preserveOrder || c.Blocking[argExprs[i]]
	}

	args := make([]string, len(argExprs))
	for i, argExpr := range argExprs {
		var argType types.Type
		switch {
		case varargType != nil && i >= paramsLen-1:
			argType = varargType.Elem()
		default:
			argType = sig.Params().At(i).Type()
		}

		var arg string
		switch {
		case clone:
			arg = c.translateImplicitConversionWithCloning(argExpr, argType).String()
		default:
			arg = c.translateImplicitConversion(argExpr, argType).String()
		}

		if preserveOrder && c.p.Types[argExpr].Value == nil {
			argVar := c.newVariable("_arg")
			c.Printf("%s = %s;", argVar, arg)
			arg = argVar
		}

		args[i] = arg
	}

	if varargType != nil {
		return append(args[:paramsLen-1], fmt.Sprintf("new %s([%s])", c.typeName(varargType), strings.Join(args[paramsLen-1:], ", ")))
	}
	return args
}

func newFuncFrom(p *Package, parent string, obj types.Object, sig *types.Signature) (Func, error) {
	haserr := false
	res := sig.Results()
	var ret types.Type

	switch res.Len() {
	case 2:
		if !isErrorType(res.At(1).Type()) {
			return Func{}, fmt.Errorf(
				"bind: second result value must be of type error: %s",
				obj,
			)
		}
		haserr = true
		ret = res.At(0).Type()

	case 1:
		if isErrorType(res.At(0).Type()) {
			haserr = true
			ret = nil
		} else {
			ret = res.At(0).Type()
		}
	case 0:
		ret = nil
	default:
		return Func{}, fmt.Errorf("bind: too many results to return: %v", obj)
	}

	id := obj.Pkg().Name() + "_" + obj.Name()
	if parent != "" {
		id = obj.Pkg().Name() + "_" + parent + "_" + obj.Name()
	}

	return Func{
		pkg:  p,
		sig:  newSignatureFrom(p, sig),
		typ:  obj.Type(),
		name: obj.Name(),
		id:   id,
		doc:  p.getDoc(parent, obj),
		ret:  ret,
		err:  haserr,
	}, nil
}

func newSignatureFrom(pkg *Package, sig *types.Signature) *Signature {
	var recv *Var
	if sig.Recv() != nil {
		recv = newVarFrom(pkg, sig.Recv())
	}

	return &Signature{
		ret:  newVarsFrom(pkg, sig.Results()),
		args: newVarsFrom(pkg, sig.Params()),
		recv: recv,
	}
}

func (c *converter) convertSignature(v *gotypes.Signature) *types.Signature {
	if v == nil {
		return nil
	}
	if v, ok := c.converted[v]; ok {
		return v.(*types.Signature)
	}
	ret := types.NewSignature(
		c.convertParamVar(v.Recv()),
		c.convertTuple(v.Params(), c.convertParamVar),
		c.convertTuple(v.Results(), c.convertParamVar),
		v.Variadic(),
	)
	c.converted[v] = ret
	return ret
}

func (w *Walker) writeSignature(buf *bytes.Buffer, sig *types.Signature) {
	w.writeParams(buf, sig.Params(), sig.Variadic())
	switch res := sig.Results(); res.Len() {
	case 0:
		// nothing to do
	case 1:
		buf.WriteByte(' ')
		w.writeType(buf, res.At(0).Type())
	default:
		buf.WriteByte(' ')
		w.writeParams(buf, res, false)
	}
}

// sigParamsCompatible determines if the parameter parts of two signatures of functions are compatible.
// They are compatible if:
// - The number of parameters equal and the types of parameters are compatible for each of them.
// - The latter parameters have exactly one extra parameter which is a variadic parameter.
func sigParamsCompatible(s1, s2 *types.Signature) bool {
	extra := tuplesCompatibleExtra(s1.Params(), s2.Params(), cmpLower)

	switch {
	case extra == nil:
		// s2 params is incompatible with s1 params
		return false

	case len(extra) == 0:
		// s2 params is compatible with s1 params
		return true

	case len(extra) == 1:
		// s2 params is compatible with s1 params with an extra variadic arg
		if s1.Variadic() == false && s2.Variadic() == true {
			return true
		}
	}

	return false
}

func sigResultsCompatible(s1, s2 *types.Signature) bool {
	if s1.Results().Len() == 0 {
		return true
	}

	extra := tuplesCompatibleExtra(s1.Results(), s2.Results(), cmpUpper)

	switch {
	case extra == nil:
		return false
	case len(extra) == 0:
		return true
	}

	return false
}

func (p *printer) writeSignatureInternal(this *types.Package, sig *types.Signature, visited []types.Type) {
	p.writeTuple(this, sig.Params(), sig.Variadic(), visited)

	res := sig.Results()
	n := res.Len()
	if n == 0 {
		// no result
		return
	}

	p.print(" ")
	if n == 1 && res.At(0).Name() == "" {
		// single unnamed result
		p.writeTypeInternal(this, res.At(0).Type(), visited)
		return
	}

	// multiple or named result(s)
	p.writeTuple(this, res, false, visited)
}

func changeRecv(s *types.Signature, recv *types.Var) *types.Signature {
	return types.NewSignature(recv, s.Params(), s.Results(), s.Variadic())
}

func (c *funcContext) translateBuiltin(name string, sig *types.Signature, args []ast.Expr, ellipsis bool) *expression {
	switch name {
	case "new":
		t := sig.Results().At(0).Type().(*types.Pointer)
		if c.p.Pkg.Path() == "syscall" && types.Identical(t.Elem().Underlying(), types.Typ[types.Uintptr]) {
			return c.formatExpr("new Uint8Array(8)")
		}
		switch t.Elem().Underlying().(type) {
		case *types.Struct, *types.Array:
			return c.formatExpr("%e", c.zeroValue(t.Elem()))
		default:
			return c.formatExpr("$newDataPointer(%e, %s)", c.zeroValue(t.Elem()), c.typeName(t))
		}
	case "make":
		switch argType := c.p.TypeOf(args[0]).Underlying().(type) {
		case *types.Slice:
			t := c.typeName(c.p.TypeOf(args[0]))
			if len(args) == 3 {
				return c.formatExpr("$makeSlice(%s, %f, %f)", t, args[1], args[2])
			}
			return c.formatExpr("$makeSlice(%s, %f)", t, args[1])
		case *types.Map:
			if len(args) == 2 && c.p.Types[args[1]].Value == nil {
				return c.formatExpr(`((%1f < 0 || %1f > 2147483647) ? $throwRuntimeError("makemap: size out of range") : {})`, args[1])
			}
			return c.formatExpr("{}")
		case *types.Chan:
			length := "0"
			if len(args) == 2 {
				length = c.formatExpr("%f", args[1]).String()
			}
			return c.formatExpr("new $Chan(%s, %s)", c.typeName(c.p.TypeOf(args[0]).Underlying().(*types.Chan).Elem()), length)
		default:
			panic(fmt.Sprintf("Unhandled make type: %T\n", argType))
		}
	case "len":
		switch argType := c.p.TypeOf(args[0]).Underlying().(type) {
		case *types.Basic:
			return c.formatExpr("%e.length", args[0])
		case *types.Slice:
			return c.formatExpr("%e.$length", args[0])
		case *types.Pointer:
			return c.formatExpr("(%e, %d)", args[0], argType.Elem().(*types.Array).Len())
		case *types.Map:
			return c.formatExpr("$keys(%e).length", args[0])
		case *types.Chan:
			return c.formatExpr("%e.$buffer.length", args[0])
		// length of array is constant
		default:
			panic(fmt.Sprintf("Unhandled len type: %T\n", argType))
		}
	case "cap":
		switch argType := c.p.TypeOf(args[0]).Underlying().(type) {
		case *types.Slice, *types.Chan:
			return c.formatExpr("%e.$capacity", args[0])
		case *types.Pointer:
			return c.formatExpr("(%e, %d)", args[0], argType.Elem().(*types.Array).Len())
		// capacity of array is constant
		default:
			panic(fmt.Sprintf("Unhandled cap type: %T\n", argType))
		}
	case "panic":
		return c.formatExpr("$panic(%s)", c.translateImplicitConversion(args[0], types.NewInterface(nil, nil)))
	case "append":
		if ellipsis || len(args) == 1 {
			argStr := c.translateArgs(sig, args, ellipsis, false)
			return c.formatExpr("$appendSlice(%s, %s)", argStr[0], argStr[1])
		}
		sliceType := sig.Results().At(0).Type().Underlying().(*types.Slice)
		return c.formatExpr("$append(%e, %s)", args[0], strings.Join(c.translateExprSlice(args[1:], sliceType.Elem()), ", "))
	case "delete":
		keyType := c.p.TypeOf(args[0]).Underlying().(*types.Map).Key()
		return c.formatExpr(`delete %e[%s.keyFor(%s)]`, args[0], c.typeName(keyType), c.translateImplicitConversion(args[1], keyType))
	case "copy":
		if basic, isBasic := c.p.TypeOf(args[1]).Underlying().(*types.Basic); isBasic && isString(basic) {
			return c.formatExpr("$copyString(%e, %e)", args[0], args[1])
		}
		return c.formatExpr("$copySlice(%e, %e)", args[0], args[1])
	case "print", "println":
		return c.formatExpr("console.log(%s)", strings.Join(c.translateExprSlice(args, nil), ", "))
	case "complex":
		argStr := c.translateArgs(sig, args, ellipsis, false)
		return c.formatExpr("new %s(%s, %s)", c.typeName(sig.Results().At(0).Type()), argStr[0], argStr[1])
	case "real":
		return c.formatExpr("%e.$real", args[0])
	case "imag":
		return c.formatExpr("%e.$imag", args[0])
	case "recover":
		return c.formatExpr("$recover()")
	case "close":
		return c.formatExpr(`$close(%e)`, args[0])
	default:
		panic(fmt.Sprintf("Unhandled builtin: %s\n", name))
	}
}

func (f *Finder) call(sig *types.Signature, args []ast.Expr) {
	if len(args) == 0 {
		return
	}

	// Ellipsis call?  e.g. f(x, y, z...)
	if _, ok := args[len(args)-1].(*ast.Ellipsis); ok {
		for i, arg := range args {
			// The final arg is a slice, and so is the final param.
			f.assign(sig.Params().At(i).Type(), f.expr(arg))
		}
		return
	}

	var argtypes []types.Type

	// Gather the effective actual parameter types.
	if tuple, ok := f.info.Types[args[0]].Type.(*types.Tuple); ok {
		// f(g()) call where g has multiple results?
		f.expr(args[0])
		// unpack the tuple
		for i := 0; i < tuple.Len(); i++ {
			argtypes = append(argtypes, tuple.At(i).Type())
		}
	} else {
		for _, arg := range args {
			argtypes = append(argtypes, f.expr(arg))
		}
	}

	// Assign the actuals to the formals.
	if !sig.Variadic() {
		for i, argtype := range argtypes {
			f.assign(sig.Params().At(i).Type(), argtype)
		}
	} else {
		// The first n-1 parameters are assigned normally.
		nnormals := sig.Params().Len() - 1
		for i, argtype := range argtypes[:nnormals] {
			f.assign(sig.Params().At(i).Type(), argtype)
		}
		// Remaining args are assigned to elements of varargs slice.
		tElem := sig.Params().At(nnormals).Type().(*types.Slice).Elem()
		for i := nnormals; i < len(argtypes); i++ {
			f.assign(tElem, argtypes[i])
		}
	}
}

func (b *Builder) convertSignature(u types.Universe, t *tc.Signature) *types.Signature {
	signature := &types.Signature{}
	for i := 0; i < t.Params().Len(); i++ {
		signature.Parameters = append(signature.Parameters, b.walkType(u, nil, t.Params().At(i).Type()))
	}
	for i := 0; i < t.Results().Len(); i++ {
		signature.Results = append(signature.Results, b.walkType(u, nil, t.Results().At(i).Type()))
	}
	if r := t.Recv(); r != nil {
		signature.Receiver = b.walkType(u, nil, r.Type())
	}
	signature.Variadic = t.Variadic()
	return signature
}

// lostCancelPath finds a path through the CFG, from stmt (which defines
// the 'cancel' variable v) to a return statement, that doesn't "use" v.
// If it finds one, it returns the return statement (which may be synthetic).
// sig is the function's type, if known.
func lostCancelPath(f *File, g *cfg.CFG, v *types.Var, stmt ast.Node, sig *types.Signature) *ast.ReturnStmt {
	vIsNamedResult := sig != nil && tupleContains(sig.Results(), v)

	// uses reports whether stmts contain a "use" of variable v.
	uses := func(f *File, v *types.Var, stmts []ast.Node) bool {
		found := false
		for _, stmt := range stmts {
			ast.Inspect(stmt, func(n ast.Node) bool {
				switch n := n.(type) {
				case *ast.Ident:
					if f.pkg.uses[n] == v {
						found = true
					}
				case *ast.ReturnStmt:
					// A naked return statement counts as a use
					// of the named result variables.
					if n.Results == nil && vIsNamedResult {
						found = true
					}
				}
				return !found
			})
		}
		return found
	}

	// blockUses computes "uses" for each block, caching the result.
	memo := make(map[*cfg.Block]bool)
	blockUses := func(f *File, v *types.Var, b *cfg.Block) bool {
		res, ok := memo[b]
		if !ok {
			res = uses(f, v, b.Nodes)
			memo[b] = res
		}
		return res
	}

	// Find the var's defining block in the CFG,
	// plus the rest of the statements of that block.
	var defblock *cfg.Block
	var rest []ast.Node
outer:
	for _, b := range g.Blocks {
		for i, n := range b.Nodes {
			if n == stmt {
				defblock = b
				rest = b.Nodes[i+1:]
				break outer
			}
		}
	}
	if defblock == nil {
		panic("internal error: can't find defining block for cancel var")
	}

	// Is v "used" in the remainder of its defining block?
	if uses(f, v, rest) {
		return nil
	}

	// Does the defining block return without using v?
	if ret := defblock.Return(); ret != nil {
		return ret
	}

	// Search the CFG depth-first for a path, from defblock to a
	// return block, in which v is never "used".
	seen := make(map[*cfg.Block]bool)
	var search func(blocks []*cfg.Block) *ast.ReturnStmt
	search = func(blocks []*cfg.Block) *ast.ReturnStmt {
		for _, b := range blocks {
			if !seen[b] {
				seen[b] = true

				// Prune the search if the block uses v.
				if blockUses(f, v, b) {
					continue
				}

				// Found path to return statement?
				if ret := b.Return(); ret != nil {
					if debugLostCancel {
						fmt.Printf("found path to return in block %s\n", b)
					}
					return ret // found
				}

				// Recur
				if ret := search(b.Succs); ret != nil {
					if debugLostCancel {
						fmt.Printf(" from block %s\n", b)
					}
					return ret
				}
			}
		}
//.........这里部分代码省略.........