📚 nan - Awesome Go Library for Data Structures and Algorithms
Zero allocation Nullable structures in one library with handy conversion functions, marshallers and unmarshallers.
Detailed Description of nan
nan - No Allocations Nevermore
Package nan - Zero allocation Nullable structures in one library with handy conversion functions, marshallers and unmarshallers.
Features:
- short name "nan"
- handy conversion functions
- select which marshalers you want and limit dependencies to only those you actually need
- ability to convert your custom structs to nan compatible type with Valid field and all requested encoders/decoders
Supported types:
- bool
- float32
- float64
- int
- int8
- int16
- int32
- int64
- string
- time.Time
- uint
- uint8
- uint16
- uint32
- uint64
- more types will be added as necessary
Supported marshallers:
- Standart JSON
- encoding.TextMarshaler/TextUnmarshaler. Reuses standard JSON logic and format
- jsoniter
- easyjson
- go-json
- Scylla and Cassandra. Compatible with gocql
- SQL
Usage
Simply create struct field or variable with one of the exported types and use it without any changes to external API.
JSON input/output will be converted to null or non null values. Scylla and Cassandra will use wire format compatible with gocql.
var data struct {
Code nan.NullString `json:"code"`
}
b, err := jsoniter.Marshal(data)
if err != nil {
panic(err)
}
// {"code":null}
println(string(b))
data.Code = nan.String("1")
// Equals to
// data.Code = nan.NullString{String: "1", Valid: true}
b, err = jsoniter.Marshal(data)
if err != nil {
panic(err)
}
// {"code":"1"}
println(string(b))
code := "2"
// From addr. Can has value or be nil
data.Code = nan.StringAddr(&code)
b, err = jsoniter.Marshal(data)
if err != nil {
panic(err)
}
// {"code":"2"}
println(string(b))
// To usual value from nan
codeVal := data.Code.String
// 2
println(codeVal)
// To value addr from nan
codeAddr := data.Code.Addr()
// 2
println(*codeAddr)
Helpers
How often you write something like this?
val := true
addr := &val
With nan helpers you can write shorter
addr := nan.Bool(true).Addr()
With this you got less lines of code without readability loose.
Generate marshalers
# go install github.com/kak-tus/nan/cmd/nan@latest
# nan -help
Instead of depending on the whole github.com/kak-tus/nan you can also use nan
command to select which marshalers you want. Simply run nan
with one or more arguments and it will generate implementations for the specified marshalers in the current directory. For example, running
# nan gen -json -jsoniter
will generate nan.go, json.go, jsoniter.go files in the current working directory that contain only encoding/json and jsoniter marshalers. Nothing else will be generated so you don't have to depend on all the marshalers that github.com/kak-tus/nan supports. Generated files will use current directory name as its package name. You can also specify your own package name with -pkg
argument.
Custom structs generator
Imagine, that you have custom struct
type MyStruct struct {
ID int
Name string
}
Use nan command on its file
# nan extra -json -jsoniter example/structs.go
This will generate *_nan.go near source files with json (or any other supported marshallers). And now you have nan compatible struct with all needed marshallers
var val MyStruct
nullVal := NanMyStruct(val)
// Equals to
// nullVal := NullMyStruct{MyStruct: val, Valid: true}
fmt.Println(nullVal.ID)
See example to specific of easyjson, cql, sql generation.
nan extra coommand supports any number of file names at command line.