easyjson 源码调试学习

我们可以在Edit Configuration中进行配置
然后我们在这个窗口去配置当前Go程序的参数
配置好之后点击Debug即可。

err := p.Parse(fname, fInfo.IsDir());
会解析我们输入的文件example.go
package example
type AutoGenerated struct {
Name string json:"name"
Value int json:"value"
}

解析过程中会调用
f, err := parser.ParseFile(fset, fname, nil, parser.ParseComments)
获取ast
然后获取语法树中我们感兴趣的部分
ast.Walk(&visitor{Parser: p}, f)

重点是
func (v *visitor) Visit(n ast.Node) (w ast.Visitor) {
switch n := n.(type) {
case *ast.Package:
return v
case *ast.File:
v.PkgName = n.Name.String()
return v

case *ast.GenDecl:

	v.explicit = v.needType(n.Doc.Text())



	if !v.explicit && !v.AllStructs {

		return nil

	}

	return v

case *ast.TypeSpec:

	v.name = n.Name.String()



	// Allow to specify non-structs explicitly independent of '-all' flag.

	if v.explicit {

		v.StructNames = append(v.StructNames, v.name)

		return nil

	}

	return v

case *ast.StructType:

	v.StructNames = append(v.StructNames, v.name)

	return nil

}

return nil } 解析我们感兴趣的包，结构体声明等信息

g.writeStub();
生成文件
/Users/didi/goLang/src/github.com/xiazemin/go-json/json2go/example_easyjson.go

// TEMPORARY AUTOGENERATED FILE: easyjson stub code to make the package
// compilable during generation.

package example

import (
“github.com/mailru/easyjson/jwriter”
“github.com/mailru/easyjson/jlexer”
)

func ( AutoGenerated ) MarshalJSON() ([]byte, error) { return nil, nil }
func (* AutoGenerated ) UnmarshalJSON([]byte) error { return nil }
func ( AutoGenerated ) MarshalEasyJSON(w jwriter.Writer) {}
func ( AutoGenerated ) UnmarshalEasyJSON(l *jlexer.Lexer) {}

type EasyJSON_exporter_AutoGenerated *AutoGenerated

g.writeMain()
生成临时文件 /Users/didi/goLang/src/github.com/xiazemin/go-json/json2go/easyjson-bootstrap501241316.go

// +build ignore

// TEMPORARY AUTOGENERATED FILE: easyjson bootstapping code to launch
// the actual generator.

package main

import (
“fmt”
“os”

“github.com/mailru/easyjson/gen”

pkg “github.com/xiazemin/go-json/json2go”
)

func main() {
g := gen.NewGenerator(“example_easyjson.go”)
g.SetPkg(“example”, “github.com/xiazemin/go-json/json2go”)
g.Add(pkg.EasyJSON_exporter_AutoGenerated(nil))
if err := g.Run(os.Stdout); err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
}

创建另一个临时文件
/Users/didi/goLang/src/github.com/xiazemin/go-json/json2go/example_easyjson.go.tmp

执行命令
go run -tags “” easyjson-bootstrap501241316.go
将std out 指定为example_easyjson.go.tmp

内容为
// Code generated by easyjson for marshaling/unmarshaling. DO NOT EDIT.

package example

import (
easyjson “github.com/mailru/easyjson”
jlexer “github.com/mailru/easyjson/jlexer”
json “encoding/json”
jwriter “github.com/mailru/easyjson/jwriter”
)

// suppress unused package warning
var (
_ *json.RawMessage
_ *jlexer.Lexer
_ *jwriter.Writer
_ easyjson.Marshaler
)

func easyjsonEeca4a30DecodeGithubComXiazeminGoJsonJson2go(in *jlexer.Lexer, out *AutoGenerated) {
isTopLevel := in.IsStart()
if in.IsNull() {
if isTopLevel {
in.Consumed()
}
in.Skip()
return
}
in.Delim(‘{‘)
for !in.IsDelim(‘}’) {
key := in.UnsafeString()
in.WantColon()
if in.IsNull() {
in.Skip()
in.WantComma()
continue
}
switch key {
case “name”:
out.Name = string(in.String())
case “value”:
out.Value = int(in.Int())
default:
in.SkipRecursive()
}
in.WantComma()
}
in.Delim(‘}’)
if isTopLevel {
in.Consumed()
}
}
func easyjsonEeca4a30EncodeGithubComXiazeminGoJsonJson2go(out *jwriter.Writer, in AutoGenerated) {
out.RawByte(‘{‘)
first := true
_ = first
{
const prefix string = “,"name":”
out.RawString(prefix[1:])
out.String(string(in.Name))
}
{
const prefix string = “,"value":”
out.RawString(prefix)
out.Int(int(in.Value))
}
out.RawByte(‘}’)
}
// MarshalJSON supports json.Marshaler interface
func (v AutoGenerated) MarshalJSON() ([]byte, error) {
w := jwriter.Writer{}
easyjsonEeca4a30EncodeGithubComXiazeminGoJsonJson2go(&w, v)
return w.Buffer.BuildBytes(), w.Error
}
// MarshalEasyJSON supports easyjson.Marshaler interface
func (v AutoGenerated) MarshalEasyJSON(w *jwriter.Writer) {
easyjsonEeca4a30EncodeGithubComXiazeminGoJsonJson2go(w, v)
}
// UnmarshalJSON supports json.Unmarshaler interface
func (v *AutoGenerated) UnmarshalJSON(data []byte) error {
r := jlexer.Lexer{Data: data}
easyjsonEeca4a30DecodeGithubComXiazeminGoJsonJson2go(&r, v)
return r.Error()
}
// UnmarshalEasyJSON supports easyjson.Unmarshaler interface
func (v *AutoGenerated) UnmarshalEasyJSON(l *jlexer.Lexer) {
easyjsonEeca4a30DecodeGithubComXiazeminGoJsonJson2go(l, v)
}

重命名