eslint/lib/rules/line-comment-position.js

   1 /**
   2  * @fileoverview Rule to enforce the position of line comments
   3  * @author Alberto Rodríguez
   4  */
   5 "use strict";
   6
   7 const astUtils = require("./utils/ast-utils");
   8
   9 //------------------------------------------------------------------------------
  10 // Rule Definition
  11 //------------------------------------------------------------------------------
  12
  13 module.exports = {
  14     meta: {
  15         type: "layout",
  16
  17         docs: {
  18             description: "enforce position of line comments",
  19             recommended: false,
  20             url: "https://eslint.org/docs/rules/line-comment-position"
  21         },
  22
  23         schema: [
  24             {
  25                 oneOf: [
  26                     {
  27                         enum: ["above", "beside"]
  28                     },
  29                     {
  30                         type: "object",
  31                         properties: {
  32                             position: {
  33                                 enum: ["above", "beside"]
  34                             },
  35                             ignorePattern: {
  36                                 type: "string"
  37                             },
  38                             applyDefaultPatterns: {
  39                                 type: "boolean"
  40                             },
  41                             applyDefaultIgnorePatterns: {
  42                                 type: "boolean"
  43                             }
  44                         },
  45                         additionalProperties: false
  46                     }
  47                 ]
  48             }
  49         ],
  50         messages: {
  51             above: "Expected comment to be above code.",
  52             beside: "Expected comment to be beside code."
  53         }
  54     },
  55
  56     create(context) {
  57         const options = context.options[0];
  58
  59         let above,
  60             ignorePattern,
  61             applyDefaultIgnorePatterns = true;
  62
  63         if (!options || typeof options === "string") {
  64             above = !options || options === "above";
  65
  66         } else {
  67             above = !options.position || options.position === "above";
  68             ignorePattern = options.ignorePattern;
  69
  70             if (Object.prototype.hasOwnProperty.call(options, "applyDefaultIgnorePatterns")) {
  71                 applyDefaultIgnorePatterns = options.applyDefaultIgnorePatterns;
  72             } else {
  73                 applyDefaultIgnorePatterns = options.applyDefaultPatterns !== false;
  74             }
  75         }
  76
  77         const defaultIgnoreRegExp = astUtils.COMMENTS_IGNORE_PATTERN;
  78         const fallThroughRegExp = /^\s*falls?\s?through/u;
  79         const customIgnoreRegExp = new RegExp(ignorePattern, "u");
  80         const sourceCode = context.getSourceCode();
  81
  82         //--------------------------------------------------------------------------
  83         // Public
  84         //--------------------------------------------------------------------------
  85
  86         return {
  87             Program() {
  88                 const comments = sourceCode.getAllComments();
  89
  90                 comments.filter(token => token.type === "Line").forEach(node => {
  91                     if (applyDefaultIgnorePatterns && (defaultIgnoreRegExp.test(node.value) || fallThroughRegExp.test(node.value))) {
  92                         return;
  93                     }
  94
  95                     if (ignorePattern && customIgnoreRegExp.test(node.value)) {
  96                         return;
  97                     }
  98
  99                     const previous = sourceCode.getTokenBefore(node, { includeComments: true });
 100                     const isOnSameLine = previous && previous.loc.end.line === node.loc.start.line;
 101
 102                     if (above) {
 103                         if (isOnSameLine) {
 104                             context.report({
 105                                 node,
 106                                 messageId: "above"
 107                             });
 108                         }
 109                     } else {
 110                         if (!isOnSameLine) {
 111                             context.report({
 112                                 node,
 113                                 messageId: "beside"
 114                             });
 115                         }
 116                     }
 117                 });
 118             }
 119         };
 120     }
 121 };