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Version: 0.5.2

Introduction

The KCL language provides general programming language interfaces such as C/Rust/Go/Python/Java, and the related languages are under development.

C/Rust API

The core of KCL is developed in Rust, and the C language API is exported externally for packaging and integration in high-level languages such as Go/Python/Java.

Go API

Go API is a C-API provided by CGO wrapping KCL, while providing deeper customization features to meet the needs of upper-level tools.

Abstract Model

The abstract model of the KCL Go API is as follows:

┌─────────────────┐         ┌─────────────────┐           ┌─────────────────┐
│ kcl files │ │ KCL-Go-API │ │ KCLResultList │
│ ┌───────────┐ │ │ │ │ │
│ │ 1.k │ │ │ │ │ │
│ └───────────┘ │ │ │ │ ┌───────────┐ │ ┌───────────────┐
│ ┌───────────┐ │ │ ┌───────────┐ │ │ │ KCLResult │──┼────────▶│x.Get("a.b.c") │
│ │ 2.k │ │ │ │ Run(path) │ │ │ └───────────┘ │ └───────────────┘
│ └───────────┘ │────┐ │ └───────────┘ │ │ │
│ ┌───────────┐ │ │ │ │ │ ┌───────────┐ │ ┌───────────────┐
│ │ 3.k │ │ │ │ │ │ │ KCLResult │──┼────────▶│x.Get("k", &v) │
│ └───────────┘ │ │ │ │ │ └───────────┘ │ └───────────────┘
│ ┌───────────┐ │ ├───▶│ ┌───────────┐ │──────────▶│ │
│ │setting.yml│ │ │ │ │RunFiles() │ │ │ ┌───────────┐ │ ┌───────────────┐
│ └───────────┘ │ │ │ └───────────┘ │ │ │ KCLResult │──┼────────▶│x.JSONString() │
└─────────────────┘ │ │ │ │ └───────────┘ │ └───────────────┘
│ │ │ │ │
┌─────────────────┐ │ │ │ │ ┌───────────┐ │ ┌───────────────┐
│ Options │ │ │ ┌───────────┐ │ │ │ KCLResult │──┼────────▶│x.YAMLString() │
│WithOptions │ │ │ │MustRun() │ │ │ └───────────┘ │ └───────────────┘
│WithOverrides │────┘ │ └───────────┘ │ │ │
│WithWorkDir │ │ │ │ │
│WithDisableNone │ │ │ │ │
└─────────────────┘ └─────────────────┘ └─────────────────┘

The input file contains the KCL file and the setting.yml configuration file, and Options can be used to specify additional parameters and information such as working directory. The "KCL-Go-API" part is the provided KCL execution function. The execution function executes the KCL program according to the input file and additional parameters, and finally outputs the result of KCLResultList. KCLResultList is a list of KCLResult, each KCLResult corresponding to a generated configuration file or map[string]interface{}.

Example

package main

import (
"fmt"

kcl "kcl-lang.io/kcl-go"
)


func main() {
const k_code = `
name = "kcl"
age = 1

schema Person:
name: str = "kcl"
age: int = 1

x0 = Person{}
x1 = Person{age:101}
`

result := kcl.MustRun("hello.k", kcl.WithCode(k_code)).First()
fmt.Println(result.YAMLString())

fmt.Println("----")
fmt.Println("x0.name:", result.Get("x0.name"))
fmt.Println("x1.age:", result.Get("x1.age"))

fmt.Println("----")

var person struct {
Name string
Age int
}
fmt.Printf("person: %+v\n", result.Get("x1", &person))
}

Output result:

age: 1
name: kcl
x0:
age: 1
name: kcl
x1:
age: 101
name: kcl

----
x0.name: kcl
x1.age: 101
----
person: &{Name:kcl Age:101}

Python API

Using the Python SDK requires that you have a local Python version higher than 3.7.3 and a local pip package management tool. You can use the following command to install and obtain helpful information.

python3 -m pip install kclvm --user && python3 -m kclvm --help

Command Line Tool

Prepare a KCL file named main.k

name = "kcl"
age = 1

schema Person:
name: str = "kcl"
age: int = 1

x0 = Person {}
x1 = Person {
age = 101
}

Execute the following command and get the output:

$ python3 -m kclvm hello.k
name: kcl
age: 1
x0:
name: kcl
age: 1
x1:
name: kcl
age: 101

API

In addition, we can also execute KCL files through Python code.

Prepare a KCL file named main.py

import kclvm.program.exec as kclvm_exec
import kclvm.vm.planner as planner

print(planner.plan(kclvm_exec.Run(["hello.k"]).filter_by_path_selector()))

Execute the following command and get the output:

$ python3 main.py
name: kcl
age: 1
x0:
name: kcl
age: 1
x1:
name: kcl
age: 101

You can see that the same output can be obtained through command line tools and APIs.

At present, the KCL Python SDK is still in the early preview version. The KCL team will continue to update and provide more functions in the future. For more information, see https://github.com/kcl-lang/kcl-py

REST-API

The C-API provided by KCL does not have a REST-API. The REST-API is defined by Protobuf.

Start REST Service

The RestAPI service can be started in the following way:

python3 -m pip install kclvm -U
python3 -m gunicorn "kclvm.program.rpc-server.__main__:create_app()" -t 120 -w 4 -k uvicorn.workers.UvicornWorker -b :2021

The service can then be requested via the POST protocol:

$ curl -X POST http://127.0.0.1:2021/api:protorpc/BuiltinService.Ping --data '{}'
{
"error": "",
"result": {}
}

The POST request and the returned JSON data are consistent with the structure defined by Protobuf.

BuiltinService

Where the /api:protorpc/BuiltinService.Ping path represents the Ping method of the BuiltinService service.

The complete BuiltinService is defined by Protobuf:

service BuiltinService {
rpc Ping(Ping_Args) returns(Ping_Result);
rpc ListMethod(ListMethod_Args) returns(ListMethod_Result);
}

message Ping_Args {
string value = 1;
}
message Ping_Result {
string value = 1;
}

message ListMethod_Args {
// empty
}
message ListMethod_Result {
repeated string method_name_list = 1;
}

The Ping method can verify whether the service is normal, and the ListMethod method can query the list of all services and functions provided.

KclvmService

The KclvmService service is a service related to KCL functionality. The usage is the same as the BuiltinService service.

For example, there is the following Person structure definition:

schema Person:
key: str

check:
"value" in key # 'key' is required and 'key' must contain "value"

Then we want to use Person to verify the following JSON data:

{ "key": "value" }

This can be done through the ValidateCode method of the KclvmService service. Refer to the ValidateCode_Args structure of the ValidateCode method:

message ValidateCode_Args {
string data = 1;
string code = 2;
string schema = 3;
string attribute_name = 4;
string format = 5;
}

Construct the JSON data required by the POST request according to the ValidateCode_Args structure, which contains the Person definition and the JSON data to be verified:

{
"code": "\nschema Person:\n key: str\n\n check:\n \"value\" in key # 'key' is required and 'key' must contain \"value\"\n",
"data": "{\"key\": \"value\"}"
}

Save this JSON data to the vet-hello.json file and verify it with the following command:

$ curl -X POST \
http://127.0.0.1:2021/api:protorpc/KclvmService.ValidateCode \
-H "accept: application/json" \
--data @./vet-hello.json
{
"error": "",
"result": {
"success": true
}
}

APIs in other languages

Coming soon