web3.js/lib/web3/function.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 function.js
 * @author Marek Kotewicz <[email protected]>
 * @date 2015
 */

var web3 = require('../web3');
var coder = require('../solidity/coder');
var utils = require('../utils/utils');

/**
 * This prototype should be used to call/sendTransaction to solidity functions
 */
var SolidityFunction = function (json, address) {
    this._inputTypes = json.inputs.map(function (i) {
        return i.type;
    });
    this._outputTypes = json.outputs.map(function (i) {
        return i.type;
    });
    this._constant = json.constant;
    this._name = utils.transformToFullName(json);
    this._address = address;
};

SolidityFunction.prototype.extractCallback = function (args) {
    if (utils.isFunction(args[args.length - 1])) {
        return args.pop(); // modify the args array!
    }
};

/**
 * Should be used to create payload from arguments
 *
 * @method toPayload
 * @param {Array} solidity function params
 * @param {Object} optional payload options
 */
SolidityFunction.prototype.toPayload = function (args) {
    var options = {};
    if (args.length > this._inputTypes.length && utils.isObject(args[args.length -1])) {
        options = args[args.length - 1];
    }
    options.to = this._address;
    options.data = '0x' + this.signature() + coder.encodeParams(this._inputTypes, args);
    return options;
};

/**
 * Should be used to get function signature
 *
 * @method signature
 * @return {String} function signature
 */
SolidityFunction.prototype.signature = function () {
    return web3.sha3(web3.fromAscii(this._name)).slice(2, 10);
};


SolidityFunction.prototype.unpackOutput = function (output) {
    if (output === null) {
        return;
    }

    output = output.length >= 2 ? output.slice(2) : output;
    var result = coder.decodeParams(this._outputTypes, output);
    return result.length === 1 ? result[0] : result;
};

/**
 * Calls a contract function.
 *
 * @method call
 * @param {...Object} Contract function arguments
 * @param {function} If the last argument is a function, the contract function
 *   call will be asynchronous, and the callback will be passed the
 *   error and result.
 * @return {String} output bytes
 */
SolidityFunction.prototype.call = function () {
    var args = Array.prototype.slice.call(arguments);
    var callback = this.extractCallback(args);
    var payload = this.toPayload(args);

    if (!callback) {
        var output = web3.eth.call(payload, callback);
        return this.unpackOutput(output);
    } 
        
    var self = this;
    web3.eth.call(payload, function (error, output) {
        callback(error, self.unpackOutput(output));
    });
};

/**
 * Should be used to sendTransaction to solidity function
 *
 * @method sendTransaction
 * @param {Object} options
 */
SolidityFunction.prototype.sendTransaction = function () {
    var args = Array.prototype.slice.call(arguments);
    var callback = this.extractCallback(args);
    var payload = this.toPayload(args);

    if (!callback) {
        web3.eth.sendTransaction(payload);
        return;
    }

    web3.eth.sendTransaction(payload, callback);
};

/**
 * Should be used to get function display name
 *
 * @method displayName
 * @return {String} display name of the function
 */
SolidityFunction.prototype.displayName = function () {
    return utils.extractDisplayName(this._name);
};

/**
 * Should be used to get function type name
 *
 * @method typeName
 * @return {String} type name of the function
 */
SolidityFunction.prototype.typeName = function () {
    return utils.extractTypeName(this._name);
};

/**
 * Should be called to execute function
 *
 * @method execute
 */
SolidityFunction.prototype.execute = function () {
    var transaction = !this._constant;

    // send transaction
    if (transaction) {
        return this.sendTransaction.apply(this, Array.prototype.slice.call(arguments));
    }

    // call
    return this.call.apply(this, Array.prototype.slice.call(arguments));
};

/**
 * Should be called to attach function to contract
 *
 * @method attachToContract
 * @param {Contract}
 */
SolidityFunction.prototype.attachToContract = function (contract) {
    var execute = this.execute.bind(this);
    execute.call = this.call.bind(this);
    execute.sendTransaction = this.sendTransaction.bind(this);
    var displayName = this.displayName();
    if (!contract[displayName]) {
        contract[displayName] = execute;
    }
    contract[displayName][this.typeName()] = execute; // circular!!!!
};

module.exports = SolidityFunction;