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node_modules/eslint/lib/rules/eqeqeq.js 3.75 KB
c39994410   Ryan Glover   wip converting to...
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  /**
   * @fileoverview Rule to flag statements that use != and == instead of !== and ===
   * @author Nicholas C. Zakas
   * @copyright 2013 Nicholas C. Zakas. All rights reserved.
   * See LICENSE file in root directory for full license.
   */
  
  "use strict";
  
  //------------------------------------------------------------------------------
  // Rule Definition
  //------------------------------------------------------------------------------
  
  module.exports = function(context) {
  
      var sourceCode = context.getSourceCode(),
          replacements = {
              "==": "===",
              "!=": "!=="
          };
  
      /**
       * Checks if an expression is a typeof expression
       * @param  {ASTNode} node The node to check
       * @returns {boolean} if the node is a typeof expression
       */
      function isTypeOf(node) {
          return node.type === "UnaryExpression" && node.operator === "typeof";
      }
  
      /**
       * Checks if either operand of a binary expression is a typeof operation
       * @param {ASTNode} node The node to check
       * @returns {boolean} if one of the operands is typeof
       * @private
       */
      function isTypeOfBinary(node) {
          return isTypeOf(node.left) || isTypeOf(node.right);
      }
  
      /**
       * Checks if operands are literals of the same type (via typeof)
       * @param {ASTNode} node The node to check
       * @returns {boolean} if operands are of same type
       * @private
       */
      function areLiteralsAndSameType(node) {
          return node.left.type === "Literal" && node.right.type === "Literal" &&
                  typeof node.left.value === typeof node.right.value;
      }
  
      /**
       * Checks if one of the operands is a literal null
       * @param {ASTNode} node The node to check
       * @returns {boolean} if operands are null
       * @private
       */
      function isNullCheck(node) {
          return (node.right.type === "Literal" && node.right.value === null) ||
                  (node.left.type === "Literal" && node.left.value === null);
      }
  
      /**
       * Gets the location (line and column) of the binary expression's operator
       * @param {ASTNode} node The binary expression node to check
       * @param {String} operator The operator to find
       * @returns {Object} { line, column } location of operator
       * @private
       */
      function getOperatorLocation(node) {
          var opToken = context.getTokenAfter(node.left);
          return {line: opToken.loc.start.line, column: opToken.loc.start.column};
      }
  
      return {
          "BinaryExpression": function(node) {
              if (node.operator !== "==" && node.operator !== "!=") {
                  return;
              }
  
              if (context.options[0] === "smart" && (isTypeOfBinary(node) ||
                      areLiteralsAndSameType(node) || isNullCheck(node))) {
                  return;
              }
  
              if (context.options[0] === "allow-null" && isNullCheck(node)) {
                  return;
              }
  
              context.report({
                  node: node,
                  loc: getOperatorLocation(node),
                  message: "Expected '{{op}}=' and instead saw '{{op}}'.",
                  data: { op: node.operator },
                  fix: function(fixer) {
                      var tokens = sourceCode.getTokensBetween(node.left, node.right),
                          opToken,
                          i;
  
                      for (i = 0; i < tokens.length; ++i) {
                          if (tokens[i].value === node.operator) {
                              opToken = tokens[i];
                              break;
                          }
                      }
  
                      return fixer.replaceTextRange(opToken.range, replacements[node.operator]);
                  }
              });
  
          }
      };
  
  };
  
  module.exports.schema = [
      {
          "enum": ["smart", "allow-null"]
      }
  ];