Golang运行时动态生成结构体

builder.go

@@ -0,0 +1,185 @@
+package dynamicstruct
+
+import "reflect"
+
+type (
+	// Builder 运行时动态生成结构体的接口约束
+	Builder interface {
+		// AddField 添加结构体字段
+		AddField(name string, pkg string, typ any, tag string, anonymous bool) Builder
+		// RemoveField 移除指定名称的结构体字段
+		RemoveField(name string) Builder
+		// HasField 检测指定名称的结构体字段是否存在
+		HasField(name string) bool
+		// GetField 根据名称获取结构体字段定义
+		GetField(name string) FieldConfig
+		// Build 返回动态定义的结构体.
+		Build() DynamicStruct
+	}
+
+	// FieldConfig 结构体字段的定义.
+	FieldConfig interface {
+		// SetType 设置字段类型.
+		SetType(typ any) FieldConfig
+		// SetTag 设置字段 tag.
+		SetTag(tag string) FieldConfig
+	}
+
+	// DynamicStruct contains defined dynamic struct.
+	// This definition can't be changed anymore, once is built.
+	// It provides a method for creating new instances of same defintion.
+	DynamicStruct interface {
+		// New 获取结构体实例, 所有字段值均为对应类型的初始零值
+		New() any
+
+		// NewSliceOfStructs slice实例化
+		NewSliceOfStructs() any
+
+		// NewMapOfStructs map 或者 struct实例化
+		NewMapOfStructs(key any) any
+	}
+
+	builderImpl struct {
+		fields []*fieldConfigImpl
+	}
+
+	fieldConfigImpl struct {
+		name      string
+		pkg       string
+		typ       any
+		tag       string
+		anonymous bool
+	}
+
+	dynamicStructImpl struct {
+		definition reflect.Type
+	}
+)
+
+// NewStruct 获取builder实例
+func NewStruct() Builder {
+	return &builderImpl{
+		fields: []*fieldConfigImpl{},
+	}
+}
+
+// ExtendStruct 基于已有结构体, 生成动态结构体(相当于继承指定的结构体属性)
+func ExtendStruct(value ...any) Builder {
+	return MergeStructs(value...)
+}
+
+// MergeStructs 多个结构体合并成一个动态结构体
+func MergeStructs(values ...any) Builder {
+	builder := NewStruct()
+
+	for _, value := range values {
+		valueOf := reflect.Indirect(reflect.ValueOf(value))
+		typeOf := valueOf.Type()
+
+		for i := 0; i < valueOf.NumField(); i++ {
+			fVal := valueOf.Field(i)
+			fTyp := typeOf.Field(i)
+			builder.(*builderImpl).AddField(fTyp.Name, fTyp.PkgPath, fVal.Interface(), string(fTyp.Tag), fTyp.Anonymous)
+		}
+	}
+
+	return builder
+}
+
+// AddField 添加结构体字段
+func (b *builderImpl) AddField(name string, pkg string, typ any, tag string, anonymous bool) Builder {
+	if existFieldCfg := b.GetField(name); nil != existFieldCfg {
+		// 说明已存在指定名称字段
+		// 重复添加, 则会议后面的标签以及类型, 覆盖前面的值
+		existFieldCfg.SetTag(tag)
+		existFieldCfg.SetType(typ)
+		return b
+	}
+	b.fields = append(b.fields, &fieldConfigImpl{
+		name:      name,
+		typ:       typ,
+		tag:       tag,
+		anonymous: anonymous,
+		pkg:       pkg,
+	})
+	return b
+}
+
+// RemoveField 根据名称移除结构体字段
+func (b *builderImpl) RemoveField(name string) Builder {
+	newFieldList := make([]*fieldConfigImpl, 0)
+	for i := range b.fields {
+		if b.fields[i].name == name {
+			continue
+		}
+		newFieldList = append(newFieldList, b.fields[i])
+	}
+	b.fields = newFieldList
+	return b
+}
+
+// HasField 是否存在指定字段
+func (b *builderImpl) HasField(name string) bool {
+	for i := range b.fields {
+		if b.fields[i].name == name {
+			return true
+		}
+	}
+	return false
+}
+
+// GetField 根据名称获取字段配置, 不存在, 返回nil
+func (b *builderImpl) GetField(name string) FieldConfig {
+	for i := range b.fields {
+		if b.fields[i].name == name {
+			return b.fields[i]
+		}
+	}
+	return nil
+}
+
+// Build 构建动态结构体
+func (b *builderImpl) Build() DynamicStruct {
+	var structFields []reflect.StructField
+
+	for _, field := range b.fields {
+		structFields = append(structFields, reflect.StructField{
+			Name:      field.name,
+			PkgPath:   field.pkg,
+			Type:      reflect.TypeOf(field.typ),
+			Tag:       reflect.StructTag(field.tag),
+			Anonymous: field.anonymous,
+		})
+	}
+
+	return &dynamicStructImpl{
+		definition: reflect.StructOf(structFields),
+	}
+}
+
+// SetType 设置字段类型
+func (f *fieldConfigImpl) SetType(typ any) FieldConfig {
+	f.typ = typ
+	return f
+}
+
+// SetTag 设置字段标签
+func (f *fieldConfigImpl) SetTag(tag string) FieldConfig {
+	f.tag = tag
+	return f
+}
+
+// New 创建动态结构体实例
+func (ds *dynamicStructImpl) New() any {
+	return reflect.New(ds.definition).Interface()
+}
+
+// NewSliceOfStructs 创建动态结构体切片实例
+func (ds *dynamicStructImpl) NewSliceOfStructs() any {
+	return reflect.New(reflect.SliceOf(ds.definition)).Interface()
+}
+
+// NewMapOfStructs 创建动态结构体map实例
+func (ds *dynamicStructImpl) NewMapOfStructs(key any) any {
+	return reflect.New(reflect.MapOf(reflect.Indirect(reflect.ValueOf(key)).Type(), ds.definition)).Interface()
+}