definition.go

package bean

import (
	"fmt"
	"reflect"
)

// 依赖场景类型
const (
	PROTOTYPE = "prototype"
	SINGLETON = "singleton"
)

// NewReflect 创建反射
func NewReflect(i interface{}) func() reflect.Value {
	switch reflect.TypeOf(i).Kind() {
	case reflect.Func:
		return func() reflect.Value {
			return reflect.ValueOf(i)
		}
	case reflect.Struct:
		return func() reflect.Value {
			return reflect.New(reflect.TypeOf(i))
		}
	default:
		panic("Invalid type, use only func and struct")
	}
	return nil
}

// ConstructorArgs 构造器参数
type ConstructorArgs []interface{}

// Fields 字段
type Fields map[string]interface{}

// Reference 引用
type Reference struct {
	Name string
}

// NewReference 创建引用
func NewReference(name string) Reference {
	return Reference{Name: name}
}

// ReturnError 返回错误
type ReturnError struct {
	error
}

// NewReturnError 创建返回错误
func NewReturnError(err error) *ReturnError {
	return &ReturnError{err}
}

// BeanDefinition 依赖定义
type BeanDefinition struct {
	Name            string
	Reflect         func() reflect.Value
	Scope           string
	InitMethod      string
	ConstructorArgs ConstructorArgs
	Fields          Fields
	context         *ApplicationContext
}

// Refresh 刷新
func (t *BeanDefinition) Refresh() {
	if t.Scope != SINGLETON {
		return
	}
	t.context.instances.Store(t.Name, t.instance())
}

// 实例化
func (t *BeanDefinition) instance() interface{} {
	v := t.Reflect()

	// 构造器注入
	if v.Kind() == reflect.Func {
		in := []reflect.Value{}
		for _, a := range t.ConstructorArgs {
			// 引用字段处理
			if _, ok := a.(Reference); ok {
				a = t.context.GetBean(a.(Reference).Name, Fields{}, ConstructorArgs{})
			}
			in = append(in, reflect.ValueOf(a))
		}
		func() {
			defer func() {
				if err := recover(); err != nil {
					if err, ok := err.(*ReturnError); ok {
						panic(err)
					}
					panic(fmt.Sprintf("Bean name '%s' reflect %s construct failed, %s", t.Name, v.Type().String(), err))
				}
			}()
			res := v.Call(in)
			if len(res) >= 2 {
				if err, ok := res[1].Interface().(error); ok {
					panic(NewReturnError(err))
				}
			}
			v = res[0]
		}()
		if v.Kind() == reflect.Struct {
			panic(fmt.Sprintf("Bean name '%s' reflect %s return value is not a pointer type", t.Name, v.Type().String()))
		}
	}

	// 字段注入
	for k, p := range t.Fields {
		// 字段检测
		if !v.Elem().FieldByName(k).CanSet() {
			panic(fmt.Sprintf("Bean name '%s' type %s field %s cannot be found or cannot be set", t.Name, reflect.TypeOf(v.Interface()), k))
		}
		// 引用字段处理
		if _, ok := p.(Reference); ok {
			p = t.context.GetBean(p.(Reference).Name, Fields{}, ConstructorArgs{})
		}
		// 类型检测
		if v.Elem().FieldByName(k).Type().String() != reflect.TypeOf(p).String() {
			panic(fmt.Sprintf("Bean name '%s' type %s field %s value of type %s is not assignable to type %s",
				t.Name,
				reflect.TypeOf(v.Interface()),
				k,
				reflect.TypeOf(p).String(), v.Elem().FieldByName(k).Type().String()),
			)
		}
		// 常规字段处理
		v.Elem().FieldByName(k).Set(reflect.ValueOf(p))
	}

	// 执行初始化方法
	if t.InitMethod != "" {
		m := v.MethodByName(t.InitMethod)
		if !m.IsValid() {
			panic(fmt.Sprintf("Bean name '%s' type %s init method %s not found",
				t.Name,
				reflect.TypeOf(v.Interface()),
				t.InitMethod,
			))
		}
		m.Call([]reflect.Value{})
	}

	return v.Interface()
}