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node_modules/eslint/lib/rules/no-control-regex.js 4.07 KB
f7563de62   Palak Handa   first commit
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  /**
   * @fileoverview Rule to forbid control charactes from regular expressions.
   * @author Nicholas C. Zakas
   */
  
  "use strict";
  
  //------------------------------------------------------------------------------
  // Rule Definition
  //------------------------------------------------------------------------------
  
  module.exports = {
      meta: {
          docs: {
              description: "disallow control characters in regular expressions",
              category: "Possible Errors",
              recommended: true
          },
  
          schema: []
      },
  
      create(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") {
  
                  const 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;
                      }
                  }
              }
  
              return null;
          }
  
  
          const controlChar = /[\x00-\x1f]/g; // eslint-disable-line no-control-regex
          const consecutiveSlashes = /\\+/g;
          const consecutiveSlashesAtEnd = /\\+$/g;
          const stringControlChar = /\\x[01][0-9a-f]/ig;
          const stringControlCharWithoutSlash = /x[01][0-9a-f]/ig;
  
          /**
           * Return a list of the control characters in the given regex string
           * @param {string} regexStr regex as string to check
           * @returns {array} returns a list of found control characters on given string
           * @private
           */
          function getControlCharacters(regexStr) {
  
              // check control characters, if RegExp object used
              const controlChars = regexStr.match(controlChar) || [];
  
              let stringControlChars = [];
  
              // check substr, if regex literal used
              const subStrIndex = regexStr.search(stringControlChar);
  
              if (subStrIndex > -1) {
  
                  // is it escaped, check backslash count
                  const possibleEscapeCharacters = regexStr.slice(0, subStrIndex).match(consecutiveSlashesAtEnd);
  
                  const hasControlChars = possibleEscapeCharacters === null || !(possibleEscapeCharacters[0].length % 2);
  
                  if (hasControlChars) {
                      stringControlChars = regexStr.slice(subStrIndex, -1)
                          .split(consecutiveSlashes)
                          .filter(Boolean)
                          .map(x => {
                              const match = x.match(stringControlCharWithoutSlash) || [x];
  
                              return `\\${match[0]}`;
                          });
                  }
              }
  
              return controlChars.map(x => {
                  const hexCode = `0${x.charCodeAt(0).toString(16)}`.slice(-2);
  
                  return `\\x${hexCode}`;
              }).concat(stringControlChars);
          }
  
          return {
              Literal(node) {
                  const regex = getRegExp(node);
  
                  if (regex) {
                      const computedValue = regex.toString();
  
                      const controlCharacters = getControlCharacters(computedValue);
  
                      if (controlCharacters.length > 0) {
                          context.report({
                              node,
                              message: "Unexpected control character(s) in regular expression: {{controlChars}}.",
                              data: {
                                  controlChars: controlCharacters.join(", ")
                              }
                          });
                      }
                  }
              }
          };
  
      }
  };