缘起

最近阅读 [Offer来了：Java面试核心知识点精讲（框架篇）] (王磊 , 2020.6)

本系列笔记拟采用golang练习之

Talk is cheap, show me the code.

Spring

 Spring基于J2EE技术实现了一套轻量级的
Java Web Service系统应用框架。
它有很多优秀的特性，很多公司都选择把
Spring作为产品或项目的基础开发架构。

Spring的主要特性包括：
1. 轻量
2. 控制反转（Inversion of Control, IoC）
3. 面向容器
4. 面向切面（AspectOriented Programming, AOP）
5. 框架灵活

源码gitee地址：


原文链接：
  

目标

• 参考spring常用注解，使用golang编写“基于注解的静态代码增强器/生成器”

• 配置： ComponentScan，Configuration, Bean
• Bean声明：Component, Service, Controller
• Bean注入：Autowried
• AOP注解：Before, After, Around, PointCut

子目标（Day 3）

• 添加ProjectCmd以支持项目定义
• 添加文本扫描的辅助类：Chars.go, Tokens.go
• 定义代码生成服务接口ICodingService及其支撑接口

设计

• command/ProjectCmd: 项目定义指令
• common/Chars: 字符识别辅助类
• common/Tokens: 组合文本识别辅助类
• service/ICodingService: 代码生成服务接口
• service/iCodingContext: 代码生成上下文
• service/iCodingState：状态模式下的服务状态
• service/iCmdRunner：定义指令执行器接口，具体执行拟走责任链模式以便扩展
• service/tInitialState：默认的服务状态

command/ProjectCmd.go

项目定义指令

 package project_cmd

import (
    "errors"
    "fmt"
    "learning/gooop/spring/autogen/command"
    "learning/gooop/spring/autogen/common"
    "os"
    "strings"
)

// ProjectCmd defines a project with name and dir
type ProjectCmd struct {
    name string
    dir string
}

// ProjectCmdBuilder parses cli input and creates a ProjectCmd instance
type ProjectCmdBuilder int

const gProjectCmdPrefix = "project "
var gErrorInvalidProjectCmd = errors.New("invalid project cmd")

func (me *ProjectCmd) String() string {
    return fmt.Sprintf("project %s %s", me.name, me.dir)
}

func (me *ProjectCmd) Apply(ctx command.ICmdContext) error {
    panic("implements me")
}

func (me *ProjectCmdBuilder) Build(line string) (error, command.ICmd) {
    if !common.Tokens.MatchString(line, gProjectCmdPrefix) {
        return nil, nil
    }

    line = strings.TrimSpace(line[len(gProjectCmdPrefix):])
    b,name := common.Tokens.MatchIdentifier(line)
    if !b {
        return gErrorInvalidProjectCmd, nil
    }

    line = line[len(name):]
    b, spaces := common.Tokens.MatchSpaces(line)
    if !b {
        return gErrorInvalidProjectCmd, nil
    }

    line = line[len(spaces):]
    b, dir := common.Tokens.MatchDir(line)
    if !b {
        return gErrorInvalidProjectCmd, nil
    }
    _,e := os.Stat(dir)
    if e != nil {
        return e, nil
    }

    return nil, &ProjectCmd{ name, dir }
}  

common/Chars.go

字符识别辅助类

 package common


type tChars int

var Chars = new(tChars)

func (me *tChars) IsSpace(it rune) bool {
    switch it {
    case ' ':
        return true
    case '\t':
        return true
    case '\r':
        return true
    case '\n':
        return true
    }

    return false
}


func (me *tChars) Is09(it rune) bool {
    return it >= '0' && it <= '9'
}

func (me *tChars) Is19(it rune) bool {
    return it >= '1' && it <= '9'
}

func (me *tChars) IsLetter(it rune) bool {
    return (it >= 'a' && it <= 'z') || (it >= 'A' && it <= 'Z')
}

func (me *tChars) IsUnderscore(it rune) bool {
    return it == '_'
}

func (me *tChars) IsLB(it rune) bool {
    return it == '('
}

func (me *tChars) IsRB(it rune) bool {
    return it == ')'
}

func (me *tChars) IsChar(it rune, args... rune) bool {
    for _,v := range args {
        if v == it {
            return true
        }
    }
    return false
}

func (me *tChars) IsSQuote(it rune) bool {
    return me.IsChar(it, '\'')
}

func (me *tChars) IsDQuote(it rune) bool {
    return me.IsChar(it, '"')
}

func (me *tChars) IsRSplash(it rune) bool {
    return me.IsChar(it, '\\')
}

func (me *tChars) IsLSplash(it rune) bool {
    return me.IsChar(it, '/')
}  

common/Tokens.go

组合文本识别辅助类

 package common

import (
    "regexp"
    "strings"
    "sync"
)

type tTokens struct {
    cache map[string]*regexp.Regexp
    rwmutex *sync.RWMutex
}

var Tokens = newTokensLib()

func newTokensLib() *tTokens {
    it := new(tTokens)
    it.init()
    return it
}

func (me *tTokens) init() {
    me.cache = make(map[string]*regexp.Regexp)
    me.rwmutex = new(sync.RWMutex)
}

func (me *tTokens) MatchString(s string, p string) bool {
    return strings.HasPrefix(s, p)
}

func (me *tTokens) MatchRegexp(s string, p string) (bool, string) {
    me.rwmutex.RLock()
    r,ok := me.cache[p]
    me.rwmutex.RUnlock()

    if !ok {
        me.rwmutex.Lock()
        if r,ok = me.cache[p];!ok {
            r,_ = regexp.Compile(p)
        }
        me.rwmutex.Unlock()
    }

    if r == nil {
        return false, ""
    }

    if !r.MatchString(s) {
        return false, ""
    }

    return true, r.FindString(s)
}

func (me *tTokens) MatchIdentifier(s string) (bool, string) {
    return me.MatchRegexp(s, "^[_a-zA-Z]\\w{0,99}}")
}

func (me *tTokens) MatchSpaces(s string) (bool, string) {
    return me.MatchRegexp(s, "^\\s+")
}

func (me *tTokens) MatchDir(s string) (bool, string) {
    b,s := me.MatchRegexp(s, "^([a-zA-Z]\\:)?([\\\\/][^\\s/:*?<>|\\\"\\\\]+)+[\\/]?")
    if b {
        return b,s
    }

    b,s = me.MatchRegexp(s, "^\\\"([a-zA-Z]\\:)?([\\\\/][^/:*?<>|\\\"\\\\]+)+[\\/]?\\\"")
    if b {
        return b,s
    }

    b,s = me.MatchRegexp(s, "^'([a-zA-Z]\\:)?([\\\\/][^'/:*?<>|\\\"\\\\]+)+[\\/]?'")
    if b {
        return b,s
    }

    return false, ""
}  

service/ICodingService.go

代码生成服务接口

 package service

type ICodingService interface {
    iCmdRunner

    State() iCodingState
    Start()
}  

service/iCodingContext.go

代码生成上下文

 package service

// iCodingContext provides context info for iCodingState instance
type iCodingContext interface {
    HandleStateChanged(state iCodingState)
}
  

service/iCodingState.go

状态模式下的服务状态

 package service

type iCodingState interface {
    iCmdRunner
}  

service/iCmdRunner.go

定义指令执行器接口，具体执行拟走责任链模式以便扩展

 package service

import "learning/gooop/spring/autogen/command"

// iCmdRunner runs a user cmd
type iCmdRunner interface {
    Run(cmd command.ICmd) error
}  

service/tInitialState.go

默认的服务状态

 package service

import (
    "errors"
    "learning/gooop/spring/autogen/command"
)

// tInitialState is the default state for a coding service
// it will only accept ProjectCmd
type tInitialState struct {
    context iCodingContext
}

func newInitialState(c iCodingContext) iCodingState {
    it := new(tInitialState)
    it.init(c)
    return it
}

func (me *tInitialState) init(c iCodingContext) {
    me.context = c
}

var gErrorProjectDefineRequired = errors.New("project not defined: project <name> <dir>")


func (me *tInitialState) Run(cmd command.ICmd) error {
    panic("implement me")
}  

（未完待续）