/**
   * @fileoverview Rule to forbid control charactes from regular expressions.
   * @author Nicholas C. Zakas
   */
  
  "use strict";
  
  //------------------------------------------------------------------------------
  // Rule Definition
  //------------------------------------------------------------------------------
  
  module.exports = function(context) {
  
      /**
       * Get the regex expression
       * @param {ASTNode} node node to evaluate
       * @returns {*} Regex if found else null
       * @private
       */
      function getRegExp(node) {
  
          if (node.value instanceof RegExp) {
              return node.value;
          } else if (typeof node.value === "string") {
  
              var parent = context.getAncestors().pop();
              if ((parent.type === "NewExpression" || parent.type === "CallExpression") &&
              parent.callee.type === "Identifier" && parent.callee.name === "RegExp") {
  
                  // there could be an invalid regular expression string
                  try {
                      return new RegExp(node.value);
                  } catch (ex) {
                      return null;
                  }
  
              }
          } else {
              return null;
          }
  
      }
  
  
  
      return {
  
          "Literal": function(node) {
  
              var computedValue,
                  regex = getRegExp(node);
  
              if (regex) {
                  computedValue = regex.toString();
                  if (/[\x00-\x1f]/.test(computedValue)) {
                      context.report(node, "Unexpected control character in regular expression.");
                  }
              }
          }
      };
  
  };
  
  module.exports.schema = [];