Go - How to create a parser

Question

I want to build a parser but have some problems understanding how to do this.

Sample string I would like to parse

{key1 = value1 | key2 = {key3 = val         


        

Answer 1

If you are willing to convert your input to a standard JSON format, why create a parser when there are Go libraries that do the heavy lifting for you?

Given the following input file (/Users/lex/dev/go/data/jsoncfgo/fritjof.json):

Input File

{
   "key1": "value1",
   "key2" :  {
      "key3": "value3"
   },
   "key4": {
      "key5": {
         "key6": "value6"
      }
   }
}

Code Example

package main

import (
    "fmt"
    "log"
    "github.com/l3x/jsoncfgo"
)


func main() {

    configPath := "/Users/lex/dev/go/data/jsoncfgo/fritjof.json"
    cfg, err := jsoncfgo.ReadFile(configPath)
    if err != nil {
        log.Fatal(err.Error())  // Handle error here
    }

    key1 := cfg.RequiredString("key1")
    fmt.Printf("key1: %v\n\n", key1)

    key2 := cfg.OptionalObject("key2")
    fmt.Printf("key2: %v\n\n", key2)

    key4 := cfg.OptionalObject("key4")
    fmt.Printf("key4: %v\n\n", key4)

    if err := cfg.Validate(); err != nil {
        defer log.Fatalf("ERROR - Invalid config file...\n%v", err)
        return
    }
}

Output

key1: value1

key2: map[key3:value3]

key4: map[key5:map[key6:value6]]

Notes

jsoncfgo can handle any level of nested JSON objects.

For details see:

• http://l3x.github.io/golang-code-examples/2014/07/24/jsoncfgo-config-file-reader.html
• http://l3x.github.io/golang-code-examples/2014/07/25/jsoncfgo-config-file-reader-advanced.html