jsoncpy

jsoncpy is a JSON compiler frontend built entirely in C. It parses a JSON file and prints its Abstract Syntax Tree (AST). The program takes a single command-line argument: the path to the JSON file. This compiler frontend follows the JSON Grammar defined in RFC 8259 (Internet Standard).

Installation/Running

1. Clone the repository from GitHub and navigate to the project:

git clone https://github.com/maklean/jsoncpy.git
cd jsoncpy

2. Build the project with the make utility:

make

3. Run the project:

./jsoncpy <path-to-json>

Example Output

The following is the output from the program when given assets/test.json:

OBJECT (Length: 7) {
  KEY: edge_cases
    OBJECT (Length: 6) {
      KEY: zero_float
        NUMBER (FLOAT): 0
      KEY: negative_zero
        NUMBER (FLOAT): -0
      KEY: lone_negative
        NUMBER (INT): -1
      KEY: exp_no_decimal
        NUMBER (FLOAT): 5000
      KEY: negative_exp
        NUMBER (FLOAT): -0.025000000000000001
      KEY: positive_exp_sign
        NUMBER (FLOAT): 100000
    }
  KEY: strings
    OBJECT (Length: 6) {
      KEY: empty
        STRING: ""
      KEY: only_spaces
        STRING: "   "
      KEY: newline_tab
        STRING: "a
b	c"
      KEY: escaped_backslash
        STRING: "a\b"
      KEY: escaped_quote
        STRING: "say "hi""
      KEY: forward_slash
        STRING: "a/b"
    }
  KEY: arrays
    OBJECT (Length: 5) {
      KEY: single_element
        ARRAY (Length: 1) [
            NUMBER (INT): 42
        ]
      KEY: nested_arrays
        ARRAY (Length: 3) [
            ARRAY (Length: 2) [
                NUMBER (INT): 1
                NUMBER (INT): 2
            ]
            ARRAY (Length: 2) [
                NUMBER (INT): 3
                NUMBER (INT): 4
            ]
            ARRAY (Length: 2) [
                NUMBER (INT): 5
                NUMBER (INT): 6
            ]
        ]
      KEY: all_nulls
        ARRAY (Length: 3) [
            NULL
            NULL
            NULL
        ]
      KEY: all_bools
        ARRAY (Length: 4) [
            BOOLEAN: true
            BOOLEAN: false
            BOOLEAN: true
            BOOLEAN: false
        ]
      KEY: mixed
        ARRAY (Length: 5) [
            NUMBER (INT): 1
            STRING: "two"
            NULL
            BOOLEAN: false
            NUMBER (FLOAT): 3.1400000000000001
        ]
    }
  KEY: objects
    OBJECT (Length: 3) {
      KEY: single_key
        OBJECT (Length: 1) {
          KEY: x
            NUMBER (INT): 1
        }
      KEY: all_nulls
        OBJECT (Length: 3) {
          KEY: a
            NULL
          KEY: b
            NULL
          KEY: c
            NULL
        }
      KEY: numeric_looking_keys
        OBJECT (Length: 2) {
          KEY: 1key
            STRING: "value"
          KEY: key1
            STRING: "value"
        }
    }
  KEY: deeply_nested_array
    ARRAY (Length: 1) [
        ARRAY (Length: 1) [
            ARRAY (Length: 1) [
                ARRAY (Length: 1) [
                    ARRAY (Length: 1) [
                        NUMBER (INT): 42
                    ]
                ]
            ]
        ]
    ]
  KEY: null_top_level_value
    NULL
  KEY: bool_top_level
    BOOLEAN: true
}

TODO

• Support scanning exponential numbers (e.g., 2.9e-4)
• Make a Makefile
• Check for duplicate object keys
• Use arena allocator to make freeing memory easier.
• Include line number and column in error messages.
• Add a query language to traverse the AST.