web3.js/lib/solidity/formatters.js

/*
    This file is part of ethereum.js.

    ethereum.js is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    ethereum.js is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with ethereum.js.  If not, see <http://www.gnu.org/licenses/>.
*/
/** @file formatters.js
 * @authors:
 *   Marek Kotewicz <marek@ethdev.com>
 * @date 2015
 */

if (process.env.NODE_ENV !== 'build') {
    var BigNumber = require('bignumber.js'); // jshint ignore:line
}

var utils = require('../utils/utils');
var c = require('../utils/config');

/**
 * Should be called to pad string to expected length
 *
 * @method padLeft
 * @param {String} string to be padded
 * @param {Number} characters that result string should have
 * @param {String} sign, by default 0
 * @returns {String} right aligned string
 */
var padLeft = function (string, chars, sign) {
    return new Array(chars - string.length + 1).join(sign ? sign : "0") + string;
};

/**
 * Formats input value to byte representation of int
 * If value is negative, return it's two's complement
 * If the value is floating point, round it down
 *
 * @method formatInputInt
 * @param {String|Number|BigNumber} value that needs to be formatted
 * @returns {String} right-aligned byte representation of int
 */
var formatInputInt = function (value) {
    var padding = c.ETH_PADDING * 2;
    BigNumber.config(c.ETH_BIGNUMBER_ROUNDING_MODE);
    return padLeft(utils.toTwosComplement(value).round().toString(16), padding);
};

/**
 * Formats input value to byte representation of string
 *
 * @method formatInputString
 * @param {String}
 * @returns {String} left-algined byte representation of string
 */
var formatInputString = function (value) {
    return utils.fromAscii(value, c.ETH_PADDING).substr(2);
};

/**
 * Formats input value to byte representation of bool
 *
 * @method formatInputBool
 * @param {Boolean}
 * @returns {String} right-aligned byte representation bool
 */
var formatInputBool = function (value) {
    return '000000000000000000000000000000000000000000000000000000000000000' + (value ?  '1' : '0');
};

/**
 * Formats input value to byte representation of real
 * Values are multiplied by 2^m and encoded as integers
 *
 * @method formatInputReal
 * @param {String|Number|BigNumber}
 * @returns {String} byte representation of real
 */
var formatInputReal = function (value) {
    return formatInputInt(new BigNumber(value).times(new BigNumber(2).pow(128))); 
};

/**
 * Check if input value is negative
 *
 * @method signedIsNegative
 * @param {String} value is hex format
 * @returns {Boolean} true if it is negative, otherwise false
 */
var signedIsNegative = function (value) {
    return (new BigNumber(value.substr(0, 1), 16).toString(2).substr(0, 1)) === '1';
};

/**
 * Formats right-aligned output bytes to int
 *
 * @method formatOutputInt
 * @param {String} bytes
 * @returns {BigNumber} right-aligned output bytes formatted to big number
 */
var formatOutputInt = function (value) {

    value = value || "0";

    // check if it's negative number
    // it it is, return two's complement
    if (signedIsNegative(value)) {
        return new BigNumber(value, 16).minus(new BigNumber('ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff', 16)).minus(1);
    }
    return new BigNumber(value, 16);
};

/**
 * Formats right-aligned output bytes to uint
 *
 * @method formatOutputUInt
 * @param {String} bytes
 * @returns {BigNumeber} right-aligned output bytes formatted to uint
 */
var formatOutputUInt = function (value) {
    value = value || "0";
    return new BigNumber(value, 16);
};

/**
 * Formats right-aligned output bytes to real
 *
 * @method formatOutputReal
 * @param {String}
 * @returns {BigNumber} input bytes formatted to real
 */
var formatOutputReal = function (value) {
    return formatOutputInt(value).dividedBy(new BigNumber(2).pow(128)); 
};

/**
 * Formats right-aligned output bytes to ureal
 *
 * @method formatOutputUReal
 * @param {String}
 * @returns {BigNumber} input bytes formatted to ureal
 */
var formatOutputUReal = function (value) {
    return formatOutputUInt(value).dividedBy(new BigNumber(2).pow(128)); 
};

/**
 * Should be used to format output hash
 *
 * @method formatOutputHash
 * @param {String}
 * @returns {String} right-aligned output bytes formatted to hex
 */
var formatOutputHash = function (value) {
    return "0x" + value;
};

/**
 * Should be used to format output bool
 *
 * @method formatOutputBool
 * @param {String}
 * @returns {Boolean} right-aligned input bytes formatted to bool
 */
var formatOutputBool = function (value) {
    return value === '0000000000000000000000000000000000000000000000000000000000000001' ? true : false;
};

/**
 * Should be used to format output string
 *
 * @method formatOutputString
 * @param {Sttring} left-aligned hex representation of string
 * @returns {String} ascii string
 */
var formatOutputString = function (value) {
    return utils.toAscii(value);
};

/**
 * Should be used to format output address
 *
 * @method formatOutputAddress
 * @param {String} right-aligned input bytes
 * @returns {String} address
 */
var formatOutputAddress = function (value) {
    return "0x" + value.slice(value.length - 40, value.length);
};

module.exports = {
    formatInputInt: formatInputInt,
    formatInputString: formatInputString,
    formatInputBool: formatInputBool,
    formatInputReal: formatInputReal,
    formatOutputInt: formatOutputInt,
    formatOutputUInt: formatOutputUInt,
    formatOutputReal: formatOutputReal,
    formatOutputUReal: formatOutputUReal,
    formatOutputHash: formatOutputHash,
    formatOutputBool: formatOutputBool,
    formatOutputString: formatOutputString,
    formatOutputAddress: formatOutputAddress
};