mathjs/lib/expression/node/RangeNode.js

'use strict';

var operators = require('../operators');

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

  /**
   * @constructor RangeNode
   * @extends {Node}
   * create a range
   * @param {Node} start  included lower-bound
   * @param {Node} end    included upper-bound
   * @param {Node} [step] optional step
   */
  function RangeNode(start, end, step) {
    if (!(this instanceof RangeNode)) {
      throw new SyntaxError('Constructor must be called with the new operator');
    }

    // validate inputs
    if (!type.isNode(start)) throw new TypeError('Node expected');
    if (!type.isNode(end)) throw new TypeError('Node expected');
    if (step && !type.isNode(step)) throw new TypeError('Node expected');
    if (arguments.length > 3) throw new Error('Too many arguments');

    this.start = start;         // included lower-bound
    this.end = end;           // included upper-bound
    this.step = step || null;  // optional step
  }

  RangeNode.prototype = new Node();

  RangeNode.prototype.type = 'RangeNode';

  RangeNode.prototype.isRangeNode = true;

  /**
   * Check whether the RangeNode needs the `end` symbol to be defined.
   * This end is the size of the Matrix in current dimension.
   * @return {boolean}
   */
  RangeNode.prototype.needsEnd = function () {
    // find all `end` symbols in this RangeNode
    var endSymbols = this.filter(function (node) {
      return type.isSymbolNode(node) && (node.name === 'end');
    });

    return endSymbols.length > 0;
  };

  /**
   * Compile a node into a JavaScript function.
   * This basically pre-calculates as much as possible and only leaves open
   * calculations which depend on a dynamic scope with variables.
   * @param {Object} math     Math.js namespace with functions and constants. 
   * @param {Object} argNames An object with argument names as key and `true`
   *                          as value. Used in the SymbolNode to optimize
   *                          for arguments from user assigned functions
   *                          (see FunctionAssignmentNode) or special symbols
   *                          like `end` (see IndexNode).
   * @return {function} Returns a function which can be called like:
   *                        evalNode(scope: Object, args: Object, context: *)
   */
  RangeNode.prototype._compile = function (math, argNames) {
    var range = math.range;
    var evalStart = this.start._compile(math, argNames);
    var evalEnd = this.end._compile(math, argNames);

    if (this.step) {
      var evalStep = this.step._compile(math, argNames);
      
      return function evalRangeNode(scope, args, context) {
        return range(
          evalStart(scope, args, context), 
          evalEnd(scope, args, context), 
          evalStep(scope, args, context)
        );
      }
    }
    else {
      return function evalRangeNode(scope, args, context) {
        return range(
          evalStart(scope, args, context), 
          evalEnd(scope, args, context)
        );
      }
    }
  }

  /**
   * Execute a callback for each of the child nodes of this node
   * @param {function(child: Node, path: string, parent: Node)} callback
   */
  RangeNode.prototype.forEach = function (callback) {
    callback(this.start, 'start', this);
    callback(this.end, 'end', this);
    if (this.step) {
      callback(this.step, 'step', this);
    }
  };

  /**
   * Create a new RangeNode 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 {RangeNode} Returns a transformed copy of the node
   */
  RangeNode.prototype.map = function (callback) {
    return new RangeNode(
        this._ifNode(callback(this.start, 'start', this)),
        this._ifNode(callback(this.end, 'end', this)),
        this.step && this._ifNode(callback(this.step, 'step', this))
    );
  };

  /**
   * Create a clone of this node, a shallow copy
   * @return {RangeNode}
   */
  RangeNode.prototype.clone = function () {
    return new RangeNode(this.start, this.end, this.step && this.step);
  };

  /**
   * Calculate the necessary parentheses
   * @param {Node} node
   * @param {string} parenthesis
   * @return {Object} parentheses
   * @private
   */
  function calculateNecessaryParentheses(node, parenthesis) {
    var precedence = operators.getPrecedence(node, parenthesis);
    var parens = {};

    var startPrecedence = operators.getPrecedence(node.start, parenthesis);
    parens.start = ((startPrecedence !== null) && (startPrecedence <= precedence))
      || (parenthesis === 'all');

    if (node.step) {
      var stepPrecedence = operators.getPrecedence(node.step, parenthesis);
      parens.step = ((stepPrecedence !== null) && (stepPrecedence <= precedence))
        || (parenthesis === 'all');
    }

    var endPrecedence = operators.getPrecedence(node.end, parenthesis);
    parens.end = ((endPrecedence !== null) && (endPrecedence <= precedence))
      || (parenthesis === 'all');

    return parens;
  }

  /**
   * Get string representation
   * @param {Object} options
   * @return {string} str
   */
  RangeNode.prototype._toString = function (options) {
    var parenthesis = (options && options.parenthesis) ? options.parenthesis : 'keep';
    var parens = calculateNecessaryParentheses(this, parenthesis);

    //format string as start:step:stop
    var str;

    var start = this.start.toString(options);
    if (parens.start) {
      start = '(' + start + ')';
    }
    str = start;

    if (this.step) {
      var step = this.step.toString(options);
      if (parens.step) {
        step = '(' + step + ')';
      }
      str += ':' + step;
    }

    var end = this.end.toString(options);
    if (parens.end) {
      end = '(' + end + ')';
    }
    str += ':' + end;

    return str;
  };

  /**
   * Get HTML representation
   * @param {Object} options
   * @return {string} str
   */
  RangeNode.prototype.toHTML = function (options) {
    var parenthesis = (options && options.parenthesis) ? options.parenthesis : 'keep';
    var parens = calculateNecessaryParentheses(this, parenthesis);

    //format string as start:step:stop
    var str;

    var start = this.start.toHTML(options);
    if (parens.start) {
      start = '<span class="math-parenthesis math-round-parenthesis">(</span>' + start + '<span class="math-parenthesis math-round-parenthesis">)</span>';
    }
    str = start;

    if (this.step) {
      var step = this.step.toHTML(options);
      if (parens.step) {
        step = '<span class="math-parenthesis math-round-parenthesis">(</span>' + step + '<span class="math-parenthesis math-round-parenthesis">)</span>';
      }
      str += '<span class="math-operator math-range-operator">:</span>' + step;
    }

    var end = this.end.toHTML(options);
    if (parens.end) {
      end = '<span class="math-parenthesis math-round-parenthesis">(</span>' + end + '<span class="math-parenthesis math-round-parenthesis">)</span>';
    }
    str += '<span class="math-operator math-range-operator">:</span>' + end;

    return str;
  };

  /**
   * Get LaTeX representation
   * @params {Object} options
   * @return {string} str
   */
  RangeNode.prototype._toTex = function (options) {
    var parenthesis = (options && options.parenthesis) ? options.parenthesis : 'keep';
    var parens = calculateNecessaryParentheses(this, parenthesis);

    var str = this.start.toTex(options);
    if (parens.start) {
      str = '\\left(' + str + '\\right)';
    }

    if (this.step) {
      var step = this.step.toTex(options);
      if (parens.step) {
        step = '\\left(' + step + '\\right)';
      }
      str += ':' + step;
    }

    var end = this.end.toTex(options);
    if (parens.end) {
      end = '\\left(' + end + '\\right)';
    }
    str += ':' + end;

    return str;
  };

  return RangeNode;
}

exports.name = 'RangeNode';
exports.path = 'expression.node';
exports.factory = factory;