leandrosansilva/go-libconfig

A library for reading libconfig based on golang language

libconfig

A golang language library for reading libconfig file

Note

• Modified based on valyala/fastjson, fastjson is a json library.
• Refer to scan character mode to realize parsing configuration file.
  
• Implement the function of parsing configuration file similar to hyperrealm/libconfig, that is a C/C++ library.
  
• The project is still in the development stage, please do not use it in the production environment.
  

support

• skip # comment
• skip // comment
• skip /* */ comment
• scalarvalue
• Hexadecimal data
• big int
• array
• group
• list
• @include

example

parse bytes

data := []byte(`foo="bar"; baz=1234;`)
foo := libconfig.GetString(data, "foo")
fmt.Println("foo = %s\n", foo)

parse from file

data, err := ioutil.ReadFile("testdata/demo.cfg")
if err != nil {
    log.Fatal("read config file error: ", err.Error())
}

fmt.Printf("version = %s\n", libconfig.GetString(data, "version"))

parse with object

from strings

var p libconfig.Parser

v, err := p.Parse(`foo="bar"; baz=1234;`)
if err != nil {
    log.Fatal(err)
}

fmt.Printf("foo = %s\n", v.Get("foo").String())
fmt.Printf("foo = %s\n", string(v.GetStringBytes("foo")))

from file

var p libconfig.Parser

v, err := p.ParseFile("testdata/example4.cfg")
if err != nil {
    log.Fatal(err)
}

fmt.Printf("books[0].title=%s\n", v.GetArray("books")[0].GetStringBytes("title"))

parse element

scalarvalue、Hexadecimal data、big int

data := []byte(`foo="bar"; baz=1234; bigint=9223372036854775807L; float=1.0; bool=false;`)

// string
fmt.Printf("foo = %s\n", libconfig.GetString(data, "foo"))

// bytes
fmt.Printf("foo = %s\n", libconfig.GetBytes(data, "foo"))

// int
fmt.Printf("baz = %d\n", libconfig.GetInt(data, "baz"))

// hex value
fmt.Printf("baz = %s\n", libconfig.GetHex(data, "baz"))

//big int
fmt.Printf("bigint = %s\n", libconfig.GetBigint(data, "bigint").String())

// float 64
fmt.Printf("float = %v\n", libconfig.GetFloat64(data, "float"))

// bool
fmt.Printf("bool = %v\n", libconfig.GetBool(data, "bool"))

group

data := []byte(`foo={bar= 1234; baz=0;};`)

// handy parse
fmt.Printf("foo.bar = %s\n", libconfig.GetString(data, "foo", "bar"))

//object parse
var (
    p libconfig.Parser
    v *libconfig.Value    
)
v, err := p.ParseBytes(data)
if err != nil {
    log.Fatal(err)
}

// use get with multiple parameters and check error
item, err := v.Get("foo", "bar").StringBytes()
if err != nil {
    log.Fatal(err)
}
fmt.Printf("foo.bar = %s\n", string(item))

// use get with call chaining
fmt.Printf("foo.bar = %s\n", string(v.Get("foo").Get("bar").GetStringBytes()))

// use get array object
foo := v.GetObject("foo")
bar := foo.Get("bar")
fmt.Printf("my_array[0] = %s\n", bar.String())

array

data := []byte(`my_array = ["CT","CA","TX","NV","FL"];`)

// handy parse
fmt.Printf("my_array[0] = %s\n", libconfig.GetString(data, "my_array", "0"))

// object parse
var (
    p libconfig.Parser
    v *libconfig.Value
)

v, err := p.ParseBytes(data)
if err != nil {
      log.Fatal(err)
}

// use get with multiple parameters and check error
item, err := v.Get("my_array", "0").StringBytes()
if err != nil {
      log.Fatal(err)
}
fmt.Printf("my_array[0] = %s\n", string(item))

// use get with call chaining
fmt.Printf("my_array[0] = %s\n", v.Get("my_array").Get("0").String())

// use get array object
my_array := v.GetArray("my_array")
fmt.Printf("my_array[0] = %s\n", my_array[0].String())

list

data := []byte(`list = ( ( "abc", 123, true ), 1.234, ( /* an empty list */) );`)

// handy parse
fmt.Printf("list[0][0] = %s\n", libconfig.GetString(data, "list", "0", "0"))

// object parse
var (
    p libconfig.Parser
    v *libconfig.Value
)

v, err := p.ParseBytes(data)
if err != nil {
    log.Fatal(err)
}

// use get with multiple parameters and check error
item, err := v.Get("list", "0", "0").StringBytes()
if err != nil {
    log.Fatal(err)
}
fmt.Printf("list[0][0] = %s\n", string(item))

// use get with call chaining
fmt.Printf("list[0][0] = %s\n", v.Get("list").Get("0").Get("0").String())

// use get array object
list := v.GetArray("list")
first_array := list[0].GetArray()
fmt.Printf("list[0][0] = %s\n", first_array[0].String())

mix

data := []byte(`foo=([{bar=1234; baz=0;}],)`)

// handy parse
fmt.Printf("foo[0][0].bar = %d\n", libconfig.GetInt(data, "foo", "0", "0", "bar"))

// object parse
var (
    p libconfig.Parser
    v *libconfig.Value
)

v, err := p.ParseBytes(data)
if err != nil {
    log.Fatal(err)
}

// use get with multiple parameters and check error
item, err := v.Get("foo", "0", "0", "bar").Int()
if err != nil {
    log.Fatal(err)
}
fmt.Printf("foo[0][0].bar = %d\n", item)

// use get with call chaining
fmt.Printf("foo[0][0].bar = %d\n", v.Get("foo").Get("0").Get("0").GetInt("bar"))

// use get list object
foo := v.GetArray("foo")
first_list := foo[0].GetArray()
fmt.Printf("foo[0][0].bar = %s\n", first_list[0].GetObject().Get("bar"))

include

var p libconfig.Parser

// testdata/example4.cfg
v, err := p.ParseFile("testdata/example4.cfg")
if err != nil {
    log.Fatal(err)
}

// @include "cfg_includes/book*.cfg"
fmt.Printf("books[0].title=%s\n", v.GetArray("books")[0].GetStringBytes("title"))
fmt.Printf("books[0].title=%s\n", v.Get("books", "0").GetStringBytes("title"))
fmt.Printf("books[0].title=%s\n", v.Get("books").Get("0").GetStringBytes("title"))
fmt.Printf("books[0].author=%s\n", v.GetArray("books")[2].GetStringBytes("author"))

//@include "cfg_includes/cfg_subincludes/*.cfg"	
fmt.Printf("books[0].extra1=%s\n", v.GetArray("books")[0].GetStringBytes("extra1"))
fmt.Printf("books[3].extra1=%s\n", v.GetArray("books")[3].GetStringBytes("extra1"))
fmt.Printf("books[3].extra2=%d\n", v.GetArray("books")[3].GetInt("extra2"))
fmt.Printf("books[3].extra2=%d\n", v.GetInt("books", "3", "extra2"))

a complex demo

config

# Example application configuration file

version = "1.0";

application:
{
  window:
  {
    title = "My Application";
    size = { w = 640; h = 480; };
    pos = { x = 350; y = 250; };
  };

  list = ( ( "abc", 123, true ), 1.234, ( /* an empty list */) );

  books = ( { title  = "Treasure Island";
              author = "Robert Louis Stevenson";
              price  = 29.95;
              qty    = 5; },
            { title  = "Snow Crash";
              author = "Neal Stephenson";
              price  = 9.99;
              qty    = 8; } );

  misc:
  {
    pi = 3.141592654;
    bigint = 9223372036854775807L;
    columns = [ "Last Name", "First Name", "MI" ];
    bitmask = 0x1FC3;
  };
};

code

package main
import (
    "fmt"
    "log"
    "io/ioutil"
    "github.com/xiaocok/libconfig"
)
func main(){
    data, err := ioutil.ReadFile("testdata/demo.cfg")
    if err != nil {
        log.Fatal("read config file error: ", err.Error())
    }
    
    fmt.Printf("version = %s\n", libconfig.GetString(data, "version"))
    fmt.Printf("application.window.title = %s\n", libconfig.GetString(data, "application", "window", "title"))
    fmt.Printf("application.window.size.w = %d\n",  libconfig.GetInt(data, "application", "window", "size", "w"))
    fmt.Printf("application.window.size.h = %d\n", libconfig.GetInt(data, "application", "window", "size", "h"))
    fmt.Printf("application.window.pos.x = %d\n", libconfig.GetInt(data, "application", "window", "pos", "x"))
    fmt.Printf("application.window.pos.y = %d\n", libconfig.GetInt(data, "application", "window", "pos", "y"))
    
    fmt.Printf("application.list[0][0] = %s\n", libconfig.GetString(data, "application", "list", "0", "0"))
    fmt.Printf("application.list[0][1] = %d\n",  libconfig.GetInt(data, "application", "list", "0", "1"))
    fmt.Printf("application.list[0][2] = %t\n", libconfig.GetBool(data, "application", "list", "0", "2"))
    fmt.Printf("application.list[1] = %f\n",  libconfig.GetFloat64(data, "application", "list", "1"))
    fmt.Printf("application.list[2][0] =%s\n", libconfig.GetString(data, "application", "list", "2", "0"))
    
    fmt.Printf("application.books[0].title = %s\n", libconfig.GetString(data, "application", "books", "0", "title"))
    fmt.Printf("application.books[0].author = %s\n", libconfig.GetString(data, "application", "books", "0", "author"))
    fmt.Printf("application.books[0].price = %f\n", libconfig.GetFloat64(data, "application", "books", "0", "price"))
    fmt.Printf("application.books[0].qty = %d\n", libconfig.GetInt(data, "application", "books", "0", "qty"))
    fmt.Printf("application.books[1].title = %s\n", libconfig.GetString(data, "application", "books", "1", "title"))
    fmt.Printf("application.books[1].author = %s\n", libconfig.GetString(data, "application", "books", "1", "author"))
    fmt.Printf("application.books[1].price = %f\n", libconfig.GetFloat64(data, "application", "books", "1", "price"))
    fmt.Printf("application.books[1].qty = %d\n",  libconfig.GetInt(data, "application", "books", "1", "qty"))
    
    fmt.Printf("application.misc.pi = %.9f\n",  libconfig.GetFloat64(data, "application", "misc", "pi"))
    fmt.Printf("application.misc.bigint = %s\n", libconfig.GetBigint(data, "application", "misc", "bigint").String())
    fmt.Printf("application.misc.columns[0] = %s\n", libconfig.GetString(data, "application", "misc", "columns", "0"))
    fmt.Printf("application.misc.columns[1] = %s\n", libconfig.GetString(data, "application", "misc", "columns", "1"))
    fmt.Printf("application.misc.columns[2] = %s\n",  libconfig.GetString(data, "application", "misc", "columns", "2"))
    fmt.Printf("application.misc.bitmask = %d\n", libconfig.GetInt(data, "application", "misc", "bitmask"))
    fmt.Printf("application.misc.bitmask_hex = %s\n", libconfig.GetHex(data, "application", "misc", "bitmask"))
    
    // Output:
    // version = 1.0
    // application.window.title = My Application
    // application.window.size.w = 640
    // application.window.size.h = 480
    // application.window.pos.x = 350
    // application.window.pos.y = 250
    // application.list[0][0] = abc
    // application.list[0][1] = 123
    // application.list[0][2] = true
    // application.list[1] = 1.234000
    // application.list[2][0] =
    // application.books[0].title = Treasure Island
    // application.books[0].author = Robert Louis Stevenson
    // application.books[0].price = 29.950000
    // application.books[0].qty = 5
    // application.books[1].title = Snow Crash
    // application.books[1].author = Neal Stephenson
    // application.books[1].price = 9.990000
    // application.books[1].qty = 8
    // application.misc.pi = 3.141592654
    // application.misc.bigint = 9223372036854775807
    // application.misc.columns[0] = Last Name
    // application.misc.columns[1] = First Name
    // application.misc.columns[2] = MI
    // application.misc.bitmask = 8131
    // application.misc.bitmask_hex = 0x1FC3
}