context.go

package bean

import (
	"fmt"
	"sync"
)

// NewApplicationContext 创建应用上下文
func NewApplicationContext(definitions []BeanDefinition) *ApplicationContext {
	context := &ApplicationContext{
		Definitions: definitions,
	}
	context.Init()
	return context
}

// ApplicationContext 应用上下文
type ApplicationContext struct {
	Definitions     []BeanDefinition
	tidyDefinitions sync.Map
	instances       sync.Map
}

// Init 初始化
func (t *ApplicationContext) Init() {
	t.tidyDefinitions = sync.Map{}
	for _, d := range t.Definitions {
		ptr := &BeanDefinition{
			Name:            d.Name,
			Reflect:         d.Reflect,
			Scope:           d.Scope,
			InitMethod:      d.InitMethod,
			ConstructorArgs: d.ConstructorArgs,
			Fields:          d.Fields,
			context:         t,
		}
		t.tidyDefinitions.Store(d.Name, ptr)
	}
}

// GetBeanDefinition 获取依赖定义
func (t *ApplicationContext) GetBeanDefinition(name string) *BeanDefinition {
	var (
		inf interface{}
		ok  bool
	)
	if inf, ok = t.tidyDefinitions.Load(name); !ok {
		panic(fmt.Sprintf("Bean not found: %s", name))
	}
	return inf.(*BeanDefinition)
}

// GetBean 获取实例
func (t *ApplicationContext) GetBean(name string, fields Fields, args ConstructorArgs) interface{} {
	bd := merge(t.GetBeanDefinition(name), fields, args)
	if bd.Scope == SINGLETON {
		if ins, ok := t.instances.Load(name); ok {
			return ins
		}
		val := bd.instance()
		ins, _ := t.instances.LoadOrStore(name, val) // LoadOrStore 处理并发穿透
		return ins
	}
	return bd.instance()
}

// Get 快速获取实例
func (t *ApplicationContext) Get(name string) interface{} {
	return t.GetBean(name, Fields{}, ConstructorArgs{})
}

// Has 判断组件是否存在
func (t *ApplicationContext) Has(name string) (ok bool) {
	ok = true
	defer func() {
		if err := recover(); err != nil {
			ok = false
		}
	}()
	t.GetBeanDefinition(name)
	return ok
}

// 合并
// args | fields 内的字段会替换之前定义的值
// args 内的 nil 值将会忽略，不会替换处理
func merge(bd *BeanDefinition, fields Fields, args ConstructorArgs) *BeanDefinition {
	f := len(fields) > 0
	a := len(args) > 0
	if !(f || a) {
		return bd
	}
	nbd := &BeanDefinition{
		Name:            bd.Name,
		Scope:           bd.Scope,
		Reflect:         bd.Reflect,
		InitMethod:      bd.InitMethod,
		ConstructorArgs: bd.ConstructorArgs,
		Fields:          bd.Fields,
		context:         bd.context,
	}
	if a {
		// 合并替换参数，nil 忽略
		tmp := ConstructorArgs{}
		tmp = append(tmp, bd.ConstructorArgs...)
		for k, v := range args {
			if v == nil {
				continue
			}
			ok := false
			for sk := range bd.ConstructorArgs {
				if sk == k {
					ok = true
				}
			}
			if ok {
				tmp[k] = v
			} else {
				tmp = append(tmp, v)
			}
		}
		nbd.ConstructorArgs = tmp
	}
	if f {
		tmp := Fields{}
		for k, v := range bd.Fields {
			tmp[k] = v
		}
		for k, v := range fields {
			tmp[k] = v
		}
		nbd.Fields = tmp
	}
	return nbd
}