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* Copyright 2018. bigpigeon. All rights reserved.
* Use of this source code is governed by a MIT style
* license that can be found in the LICENSE file.
package main
import (
func main() {
fset := token.NewFileSet() // 位置是相对于节点
// 用ParseFile把文件解析成*ast.File节点
f, err := parser.ParseFile(fset, "data/main.go", nil, 0)
if err != nil {
// 使用types check
// 构造config
config := types.Config{
// 加载包的方式,可以通过源码或编译好的包,其中编译好的包分为gc和gccgo,前者应该是
Importer: importer.For("source", nil),
// 表示允许包里面加载c库 import "c"
FakeImportC: true,
info := &types.Info{
// 表达式对应的类型
Types: make(map[ast.Expr]types.TypeAndValue),
// 被定义的标示符
Defs: make(map[*ast.Ident]types.Object),
// 被使用的标示符
Uses: make(map[*ast.Ident]types.Object),
// 隐藏节点,匿名import包,type-specific时的case对应的当前类型,声明函数的匿名参数如var func(int)
Implicits: make(map[ast.Node]types.Object),
// 选择器,只能针对类型/对象.字段/method的选择,package.API这种不会记录在这里
Selections: make(map[*ast.SelectorExpr]*types.Selection),
// scope 记录当前库scope下的所有域,*ast.File/*ast.FuncType/... 都属于scope,详情看Scopes说明
// scope关系: 最外层Universe scope,之后Package scope,其他子scope
Scopes: make(map[ast.Node]*types.Scope),
// 记录所有package级的初始化值
InitOrder: make([]*types.Initializer, 0, 0),
// 这里Check的第一个path参数是当前pkg前缀,和FileSet的文件路径是无关的
pkg, err := config.Check("", fset, []*ast.File{f}, info)
if err != nil {
for _, name := range pkg.Scope().Names() {
obj := pkg.Scope().Lookup(name)
fmt.Printf("%s name %s type %s %T\n", fset.Position(obj.Pos()), name, obj.Type(), obj.Type())
switch x := obj.Type().(type) {
case *types.Array:
fmt.Printf("array %s len %d elem %s \n", name, x.Len(), x.Elem())
case *types.Basic:
fmt.Printf("basic %s kind %d info %v \n", name, x.Kind(), x.Info())
case *types.Chan:
fmt.Printf("chan %s dir %v elem %v \n", name, x.Dir(), x.Elem())
case *types.Interface:
fmt.Printf("interface %s it's method \n", name)
for i := 0; i < x.NumMethods(); i++ {
method := x.Method(i)
fmt.Printf("%s\n", method)
case *types.Map:
fmt.Printf("map %s it's key %s it's elem %s \n", name, x.Key(), x.Elem())
case *types.Named:
fmt.Printf("named %s it's underlying %s it's method \n", name, x.Underlying())
for i := 0; i < x.NumMethods(); i++ {
method := x.Method(i)
fmt.Printf("%s\n", method)
case *types.Pointer:
fmt.Printf("point %s it's elem %s\n", name, x.Elem())
case *types.Signature:
fmt.Printf("func %s params %s %T\n", name, x.Params(), x.Params())
fmt.Printf("func %s result %s %T\n", name, x.Results(), x.Results())
case *types.Slice:
fmt.Printf("slice %s elem %s \n", name, x.Elem())
case *types.Struct:
fmt.Printf("struct %s it's fields \n", name)
for i := 0; i < x.NumFields(); i++ {
field := x.Field(i)
fmt.Printf("%s\n", field)
// use Identical to compare type
idName1 := pkg.Scope().Lookup("idName1").Type()
idName2 := pkg.Scope().Lookup("idName2").Type()
idName3 := pkg.Scope().Lookup("idName3").Type()
idName4 := pkg.Scope().Lookup("idName4").Type()
fmt.Printf("idName1 %s idName2 %s they is same type %v\n", idName1, idName2, types.Identical(idName1, idName2))
fmt.Printf("idName1 %s idName3 %s they is same type %v\n", idName1, idName3, types.Identical(idName1, idName3))
fmt.Printf("idName1 %s idName4 %s they is same type %v\n", idName1, idName4, types.Identical(idName1, idName4))
intVal := pkg.Scope().Lookup("intVal").Type()
intVal2 := pkg.Scope().Lookup("intVal2").Type()
fmt.Printf("intVal %s intVal2 %s they is same type %v\n", intVal, intVal2, types.Identical(intVal, intVal2))
// use Implicate to match type and interface
stringer := pkg.Scope().Lookup("Stringer").Type().Underlying().(*types.Interface)
response := pkg.Scope().Lookup("Response").Type()
writeStringer := pkg.Scope().Lookup("WriteStringer").Type().Underlying().(*types.Interface)
fmt.Printf("type %s is implicate interface %s? %v\n", response, stringer, types.Implements(response, stringer))
fmt.Printf("type %s is implicate interface %s? %v\n", writeStringer, stringer, types.Implements(writeStringer, stringer))
fmt.Printf("interface %s assert to %s ? %v\n", stringer, response, types.AssertableTo(stringer, response))
fmt.Printf("interface %s assert to %s ? %v\n", writeStringer, stringer, types.AssertableTo(writeStringer, stringer))
fmt.Printf("type %s convert to %s ? %v\n", writeStringer, stringer, types.ConvertibleTo(writeStringer, stringer))
fmt.Printf("type %s convert to %s ? %v\n", intVal, intVal2, types.ConvertibleTo(intVal, intVal2))
byteType := pkg.Scope().Lookup("byteType").Type()
strType := pkg.Scope().Lookup("strType").Type()
fmt.Printf("type %s convert to %s ? %v\n", byteType, strType, types.ConvertibleTo(byteType, strType))
interfaceType := pkg.Scope().Lookup("interfaceType").Type()
int64Type := pkg.Scope().Lookup("int64Type").Type()
unintType := pkg.Scope().Lookup("unintType").Type()
fmt.Printf("type %s assign to %s ? %v\n", intVal, interfaceType, types.AssignableTo(intVal, interfaceType))
fmt.Printf("type %s assign to %s ? %v\n", int64Type, unintType, types.AssignableTo(int64Type, unintType))