mathjs/lib/expression/node/FunctionNode.js

'use strict';

var latex = require('../../util/latex');

function factory (type, config, load, typed, math) {
  var Node = load(require('./Node'));
  var SymbolNode = load(require('./SymbolNode'));

  /**
   * @constructor FunctionNode
   * @extends {Node}
   * invoke a list with arguments on a node
   * @param {string} name
   * @param {Node[]} args
   */
  function FunctionNode(name, args) {
    if (!(this instanceof FunctionNode)) {
      throw new SyntaxError('Constructor must be called with the new operator');
    }

    // validate input
    if (typeof name !== 'string') throw new TypeError('string expected for parameter "name"');
    if (!Array.isArray(args)
        || !args.every(function (arg) {return arg && arg.isNode;})) {
      throw new TypeError('Array containing Nodes expected for parameter "args"');
    }

    this.name = name;
    this.args = args || [];
  }

  FunctionNode.prototype = new Node();

  FunctionNode.prototype.type = 'FunctionNode';

  FunctionNode.prototype.isFunctionNode = true;

  /**
   * Compile the node to javascript code
   * @param {Object} defs     Object which can be used to define functions
   *                          or constants globally available for the compiled
   *                          expression
   * @return {string} js
   * @private
   */
  FunctionNode.prototype._compile = function (defs) {
    var fn = defs.math[this.name];
    var isRaw = (typeof fn === 'function') && (fn.rawArgs == true);

    // compile the parameters
    var args = this.args.map(function (arg) {
      return arg._compile(defs);
    });

    if (isRaw) {
      // pass unevaluated parameters (nodes) to the function
      var paramsName;
      do {
        paramsName = 'p' + Math.round(Math.random() * 10000);
      }
      while (paramsName in defs);
      defs[paramsName] = this.args;

      return '("' + this.name + '" in scope ? ' +
          'scope["' + this.name + '"](' + args.join(', ') + ') : ' +
          'math["' + this.name + '"]' + '(' + paramsName + ', math, scope))';
    }
    else {
      // "regular" evaluation
      var symbol = new SymbolNode(this.name);
      return symbol._compile(defs) + '(' + args.join(', ') + ')';
    }
  };

  /**
   * Execute a callback for each of the child nodes of this node
   * @param {function(child: Node, path: string, parent: Node)} callback
   */
  FunctionNode.prototype.forEach = function (callback) {
    for (var i = 0; i < this.args.length; i++) {
      callback(this.args[i], 'args[' + i + ']', this);
    }
  };

  /**
   * Create a new FunctionNode having it's childs be the results of calling
   * the provided callback function for each of the childs of the original node.
   * @param {function(child: Node, path: string, parent: Node): Node} callback
   * @returns {FunctionNode} Returns a transformed copy of the node
   */
  FunctionNode.prototype.map = function (callback) {
    var args = [];
    for (var i = 0; i < this.args.length; i++) {
      args[i] = this._ifNode(callback(this.args[i], 'args[' + i + ']', this));
    }
    return new FunctionNode(this.name, args);
  };

  /**
   * Create a clone of this node, a shallow copy
   * @return {FunctionNode}
   */
  FunctionNode.prototype.clone = function () {
    return new FunctionNode(this.name, this.args.slice(0));
  };

  //backup Node's toString function
  //@private
  var nodeToString = FunctionNode.prototype.toString;

  /**
   * Get string representation. (wrapper function)
   * This overrides parts of Node's toString function.
   * If callback is an object containing callbacks, it
   * calls the correct callback for the current node,
   * otherwise it falls back to calling Node's toString
   * function.
   *
   * @param {Object} options
   * @return {string} str
   * @override
   */
  FunctionNode.prototype.toString = function (options) {
    var customString;
    if (options && (typeof options.handler === 'object') && options.handler.hasOwnProperty(this.name)) {
      //callback is a map of callback functions
      customString = options.handler[this.name](this, options);
    }

    if (typeof customString !== 'undefined') {
      return customString;
    }

    //fall back to Node's toString
    return nodeToString.call(this, options);
  }

  /**
   * Get string representation
   * @param {Object} options
   * @return {string} str
   */
  FunctionNode.prototype._toString = function (options) {
    // format the parameters like "add(2, 4.2)"
    return this.name + '(' + this.args.join(', ') + ')';
  };

  /*
   * Expand a LaTeX template
   *
   * @param {string} template
   * @param {string} name of the function
   * @param {Array} arguments of the function ( Strings )
   * @private
   **/
  function expandTemplate(template, name, args) {
    //replace %name% with the variable 'name'
    template = template.replace(/%name%/g, name);

    //replace %0%, %1% .... with the arguments in args
    args.forEach(function (arg, index) {
      template = template.replace(RegExp('%' + index + '%', 'g'), arg);
    });

    //replace %*% with a comma separated list of all arguments
    template = template.replace('%*%', args.map(function (arg) {
        return arg;
      }).join(','));

    //replace %% with %, this comes in handy when you need a % in your LaTeX string
    template = template.replace('%%', '%');

    return template;
  }

  //backup Node's toTex function
  //@private
  var nodeToTex = FunctionNode.prototype.toTex;

  /**
   * Get LaTeX representation. (wrapper function)
   * This overrides parts of Node's toTex function.
   * If callback is an object containing callbacks, it
   * calls the correct callback for the current node,
   * otherwise it falls back to calling Node's toTex
   * function.
   *
   * @param {Object} options
   * @return {string}
   */
  FunctionNode.prototype.toTex = function (options) {
    var customTex;
    if (options && (typeof options.handler === 'object') && options.handler.hasOwnProperty(this.name)) {
      //callback is a map of callback functions
      customTex = options.handler[this.name](this, options);
    }

    if (typeof customTex !== 'undefined') {
      return customTex;
    }

    //fall back to Node's toTex
    return nodeToTex.call(this, options);
  };

  /**
   * Get LaTeX representation
   * @param {Object} options
   * @return {string} str
   */
  FunctionNode.prototype._toTex = function (options) {
    var parenthesis = (options && options.parenthesis) ? options.parenthesis : 'keep';


    var args = this.args.map(function (arg) { //get LaTeX of the arguments
      return arg.toTex(options);
    });

    var latexConverter;

    if (math[this.name] && (typeof math[this.name].toTex === 'function')) {
      //.toTex is a callback function
      latexConverter = math[this.name].toTex;
    }
    else {
      latexConverter = latex.functions[this.name];
    }

    var customToTex;
    switch (typeof latexConverter) {
      case 'function': //a callback function
        customToTex = latexConverter(this, options);
        break;
      case 'string': //a template string
        customToTex = expandTemplate(latexConverter, this.name, args);
        break;
      case 'object': //an object with different "converters" for different numbers of arguments
        switch (typeof latexConverter[args.length]) {
          case 'function':
            customToTex = latexConverter[args.length](this, options);
            break;
          case 'string':
            customToTex = expandTemplate(latexConverter[args.length], this.name, args);
            break;
        }
    }

    if (typeof customToTex !== 'undefined') {
      return customToTex;
    }

    return expandTemplate(latex.defaultTemplate, this.name, args);
  };

  /**
   * Get identifier.
   * @return {string}
   */
  FunctionNode.prototype.getIdentifier = function () {
    return this.type + ':' + this.name;
  };

  return FunctionNode;
}

exports.name = 'FunctionNode';
exports.path = 'expression.node';
exports.math = true; // request access to the math namespace as 5th argument of the factory function
exports.factory = factory;