json-prettier

• A C++ program, that can format an unformatted json string.
• Build the project using make and use the program json_formatter.out.
• Pass the input and output file path as command line arguments, and the input json will be formatted and stored in output file.

• ./json_formatter.out input.json output.json 

• Example:
  • Input json:

      {"widget": {"debug": "on","window":{"title": "Sample Konfabulator Widget", "name": "main_window", "width": 500, "height": 500
      },
                                                  "image": { 
                                      "src": "Images/Sun.png",
                              "name": "sun1",
                      "hOffset": null,
              "vOffset": null,
      "alignment": "center","flag":true
                                                                          },
                                                                  "text": {
                                                                                  "data": "Click Here",
                                                                                                      "size": 36,
                                                                                                      "style": "bold",
                                          "name": "text1",
                                  "hOffset": 250,"vOffset": 100,                      "alignment": "center",
          "onMouseUp": "sun1.opacity = (sun1.opacity / 100) * 90;"}}
                      }           

  • Formatted output:

      {
          "widget": {
              "debug": "on",
              "window": {
                  "title": "Sample Konfabulator Widget",
                  "name": "main_window",
                  "width": 500,
                  "height": 500
              },
              "image": {
                  "src": "Images/Sun.png",
                  "name": "sun1",
                  "hOffset": null,
                  "vOffset": null,
                  "alignment": "center",
                  "flag": true
              },
              "text": {
                  "data": "Click Here",
                  "size": 36,
                  "style": "bold",
                  "name": "text1",
                  "hOffset": 250,
                  "vOffset": 100,
                  "alignment": "center",
                  "onMouseUp": "sun1.opacity = (sun1.opacity / 100) * 90;"
              }
          }
      }        

Working:

• First this program parses the input string and builds the parse tree.
• Then proper amount of indentation is applied on each node.

Grammar:

JSON    -> null
        or, Object

Object  ->  Map
            or, List
            or, Integer
            or, String
            or, Boolean
            or, NULL

Integer -> (Digit)+

String -> '"' (Char)* '"'

Boolean -> 'true'
            or, 'false'

Null -> 'null'

Map     ->  '{' PairList '}'

PairList    ->  null
                or, Pair (',' Pair)*

Pair    ->  String ':' Object

List    ->  '[' ValueList ']'

ValueList   ->  null
                or, Object (',' Object)*