mathjs/lib/expression/node/UpdateNode.js

Math.js is an extensive math library for JavaScript and Node.js. It features a flexible expression parser and offers an integrated solution to work with numbers, big numbers, complex numbers, units, and matrices.

var Node = require('./Node'),
    IndexNode = require('./IndexNode');

/**
 * @constructor UpdateNode
 * @extends {Node}
 * Update a symbol value, like a(2,3) = 4.5
 *
 * @param {IndexNode} index             IndexNode containing symbol and ranges
 * @param {Node} expr                   The expression defining the symbol
 */
function UpdateNode(index, expr) {
  if (!(this instanceof UpdateNode)) {
    throw new SyntaxError('Constructor must be called with the new operator');
  }

  if (!(index instanceof IndexNode)) {
    throw new TypeError('Expected IndexNode for parameter "index"');
  }
  if (!(expr instanceof Node)) {
    throw new TypeError('Expected Node for parameter "expr"');
  }

  this.index = index;
  this.expr = expr;
}

UpdateNode.prototype = new Node();

/**
 * 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
 */
UpdateNode.prototype._compile = function (defs) {
  return 'scope["' + this.index.objectName() + '\"] = ' +
      this.index.compileSubset(defs,  this.expr._compile(defs));
};

/**
 * Find all nodes matching given filter
 * @param {Object} filter  See Node.find for a description of the filter options
 * @returns {Node[]} nodes
 */
UpdateNode.prototype.find = function (filter) {
  var nodes = [];

  // check itself
  if (this.match(filter)) {
    nodes.push(this);
  }

  // search in index
  nodes = nodes.concat(this.index.find(filter));

  // search in expression
  nodes = nodes.concat(this.expr.find(filter));

  return nodes;
};

/**
 * Get string representation
 * @return {String}
 */
UpdateNode.prototype.toString = function() {
  return this.index.toString() + ' = ' + this.expr.toString();
};

module.exports = UpdateNode;