GeoKnow/Jassa-Core

/* jshint maxdepth: 5 */

var JSONCanonical;

// Source: https://github.com/mirkokiefer/canonical-json
/*
The original version of this code is taken from Douglas Crockford's json2.js:
https://github.com/douglascrockford/JSON-js/blob/master/json2.js

I made some modifications to ensure a canonical output.
*/
var escapable = /[\\\"\x00-\x1f\x7f-\x9f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g;
var gap;
var indent;
var meta = { // table of character substitutions
        '\b': '\\b',
        '\t': '\\t',
        '\n': '\\n',
        '\f': '\\f',
        '\r': '\\r',
        '"': '\\"',
        '\\': '\\\\'
    };
var rep;

function quote(string) {

    // If the string contains no control characters, no quote characters, and no
    // backslash characters, then we can safely slap some quotes around it.
    // Otherwise we must also replace the offending characters with safe escape
    // sequences.

    escapable.lastIndex = 0;
    return escapable.test(string) ? '"' + string.replace(escapable, function(a) {
        var c = meta[a];
        return typeof c === 'string' ? c : '\\u' + ('0000' + a.charCodeAt(0).toString(16)).slice(-4);
    }) + '"' : '"' + string + '"';
}

function str(key, holder) {

    // Produce a string from holder[key].

    var i, // The loop counter.
        k, // The member key.
        v, // The member value.
        length,
        mind = gap,
        partial,
        value = holder[key];

    // If the value has a toJSON method, call it to obtain a replacement value.

    if (value && typeof value === 'object' &&
        typeof value.toJSON === 'function') {
        value = value.toJSON(key);
    }

    // If we were called with a replacer function, then call the replacer to
    // obtain a replacement value.

    if (typeof rep === 'function') {
        value = rep.call(holder, key, value);
    }

    // What happens next depends on the value's type.

    switch (typeof value) {
        case 'string':
            return quote(value);

        case 'number':

            // JSON numbers must be finite. Encode non-finite numbers as null.

            return isFinite(value) ? String(value) : 'null';

        case 'boolean':
        case 'null':

            // If the value is a boolean or null, convert it to a string. Note:
            // typeof null does not produce 'null'. The case is included here in
            // the remote chance that this gets fixed someday.

            return String(value);

            // If the type is 'object', we might be dealing with an object or an array or
            // null.

        case 'object':

            // Due to a specification blunder in ECMAScript, typeof null is 'object',
            // so watch out for that case.

            if (!value) {
                return 'null';
            }

            // Make an array to hold the partial results of stringifying this object value.

            gap += indent;
            partial = [];

            // Is the value an array?

            if (Object.prototype.toString.apply(value) === '[object Array]') {

                // The value is an array. Stringify every element. Use null as a placeholder
                // for non-JSON values.

                length = value.length;
                for (i = 0; i < length; i += 1) {
                    partial[i] = str(i, value) || 'null';
                }

                // Join all of the elements together, separated with commas, and wrap them in
                // brackets.

                v = partial.length === 0 ? '[]' : gap ? '[\n' + gap + partial.join(',\n' + gap) + '\n' + mind + ']' : '[' + partial.join(',') + ']';
                gap = mind;
                return v;
            }

            // If the replacer is an array, use it to select the members to be stringified.

            if (rep && typeof rep === 'object') {
                length = rep.length;
                for (i = 0; i < length; i += 1) {
                    if (typeof rep[i] === 'string') {
                        k = rep[i];
                        v = str(k, value);
                        if (v) {
                            partial.push(quote(k) + (gap ? ': ' : ':') + v);
                        }
                    }
                }
            } else {

                // Otherwise, iterate through all of the keys in the object.
                var keysSorted = Object.keys(value).sort();
                for (i in keysSorted) {
                    k = keysSorted[i];
                    if (Object.prototype.hasOwnProperty.call(value, k)) {
                        v = str(k, value);
                        if (v) {
                            partial.push(quote(k) + (gap ? ': ' : ':') + v);
                        }
                    }
                }
            }

            // Join all of the member texts together, separated with commas,
            // and wrap them in braces.

            v = partial.length === 0 ? '{}' : gap ? '{\n' + gap + partial.join(',\n' + gap) + '\n' + mind + '}' : '{' + partial.join(',') + '}';
            gap = mind;
            return v;
    }
}

// If the JSON object does not yet have a stringify method, give it one.
var stringify = function(value, replacer, space) {

    // The stringify method takes a value and an optional replacer, and an optional
    // space parameter, and returns a JSON text. The replacer can be a function
    // that can replace values, or an array of strings that will select the keys.
    // A default replacer method can be provided. Use of the space parameter can
    // produce text that is more easily readable.

    var i;
    gap = '';
    indent = '';

    // If the space parameter is a number, make an indent string containing that
    // many spaces.

    if (typeof space === 'number') {
        for (i = 0; i < space; i += 1) {
            indent += ' ';
        }

        // If the space parameter is a string, it will be used as the indent string.

    } else if (typeof space === 'string') {
        indent = space;
    }

    // If there is a replacer, it must be a function or an array.
    // Otherwise, throw an error.

    rep = replacer;
    if (replacer && typeof replacer !== 'function' &&
        (typeof replacer !== 'object' ||
            typeof replacer.length !== 'number')) {
        throw new Error('JSON.stringify');
    }

    // Make a fake root object containing our value under the key of ''.
    // Return the result of stringifying the value.

    return str('', {
        '': value
    });
};

JSONCanonical = {
    'stringify': stringify
};

module.exports = JSONCanonical;