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   1 /**
   2  * @fileoverview Rule to flag use of variables before they are defined
   3  * @author Ilya Volodin
   4  * @copyright 2013 Ilya Volodin. All rights reserved.
   5  */
   6
   7 "use strict";
   8
   9 //------------------------------------------------------------------------------
  10 // Constants
  11 //------------------------------------------------------------------------------
  12
  13 var NO_FUNC = "nofunc";
  14
  15 //------------------------------------------------------------------------------
  16 // Rule Definition
  17 //------------------------------------------------------------------------------
  18
  19 module.exports = function(context) {
  20
  21     function findDeclaration(name, scope) {
  22         // try searching in the current scope first
  23         for (var i = 0, l = scope.variables.length; i < l; i++) {
  24             if (scope.variables[i].name === name) {
  25                 return scope.variables[i];
  26             }
  27         }
  28         // check if there's upper scope and call recursivly till we find the variable
  29         if (scope.upper) {
  30             return findDeclaration(name, scope.upper);
  31         }
  32     }
  33
  34     function findVariables() {
  35         var scope = context.getScope();
  36         var typeOption = context.options[0];
  37
  38         function checkLocationAndReport(reference, declaration) {
  39             if (typeOption !== NO_FUNC || declaration.defs[0].type !== "FunctionName") {
  40                 if (declaration.identifiers[0].range[1] > reference.identifier.range[1]) {
  41                     context.report(reference.identifier, "{{a}} was used before it was defined", {a: reference.identifier.name});
  42                 }
  43             }
  44         }
  45
  46         scope.references.forEach(function(reference) {
  47             // if the reference is resolved check for declaration location
  48             // if not, it could be function invocation, try to find manually
  49             if (reference.resolved && reference.resolved.identifiers.length > 0) {
  50                 checkLocationAndReport(reference, reference.resolved);
  51             } else {
  52                 var declaration = findDeclaration(reference.identifier.name, scope);
  53                 // if there're no identifiers, this is a global environment variable
  54                 if (declaration && declaration.identifiers.length !== 0) {
  55                     checkLocationAndReport(reference, declaration);
  56                 }
  57             }
  58         });
  59     }
  60
  61     return {
  62         "Program": findVariables,
  63         "FunctionExpression": findVariables,
  64         "FunctionDeclaration": findVariables,
  65         "ArrowFunctionExpression": findVariables
  66     };
  67 };