source: node_modules/jsonify/lib/stringify.js@ d24f17c

'use strict';

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.
        var k; // The member key.
        var v; // The member value.
        var length;
        var mind = gap;
        var partial;
        var 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);

                case 'object':
                        if (!value) {
                                return 'null';
                        }
                        gap += indent;
                        partial = [];

                        // Array.isArray
                        if (Object.prototype.toString.apply(value) === '[object Array]') {
                                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) {
                                        k = rep[i];
                                        if (typeof k === 'string') {
                                                v = str(k, value);
                                                if (v) {
                                                        partial.push(quote(k) + (gap ? ': ' : ':') + v);
                                                }
                                        }
                                }
                        } else {
                                // Otherwise, iterate through all of the keys in the object.
                                for (k in value) {
                                        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;
                default:
        }
}

module.exports = function (value, replacer, space) {
        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 += ' ';
                }
        } else if (typeof space === 'string') {
                // If the space parameter is a string, it will be used as the indent 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 });
};