docker/swarmkit

package deepcopy

import (
    "fmt"
    "time"

    "github.com/gogo/protobuf/types"
)

// CopierFrom can be implemented if an object knows how to copy another into itself.
type CopierFrom interface {
    // Copy takes the fields from src and copies them into the target object.
    //
    // Calling this method with a nil receiver or a nil src may panic.
    CopyFrom(src interface{})
}

// Copy copies src into dst. dst and src must have the same type.
//
// If the type has a copy function defined, it will be used.
//
// Default implementations for builtin types and well known protobuf types may
// be provided.
//
// If the copy cannot be performed, this function will panic. Make sure to test
// types that use this function.
func Copy(dst, src interface{}) {
    switch dst := dst.(type) {
    case *types.Any:
        src := src.(*types.Any)
        dst.TypeUrl = src.TypeUrl
        if src.Value != nil {
            dst.Value = make([]byte, len(src.Value))
            copy(dst.Value, src.Value)
        } else {
            dst.Value = nil
        }
    case *types.Duration:
        src := src.(*types.Duration)
        *dst = *src
    case *time.Duration:
        src := src.(*time.Duration)
        *dst = *src
    case *types.Timestamp:
        src := src.(*types.Timestamp)
        *dst = *src
    case *types.BoolValue:
        src := src.(*types.BoolValue)
        *dst = *src
    case *types.Int64Value:
        src := src.(*types.Int64Value)
        *dst = *src
    case CopierFrom:
        dst.CopyFrom(src)
    default:
        panic(fmt.Sprintf("Copy for %T not implemented", dst))
    }

}