eslint/lib/rules/switch-colon-spacing.js

   1 /**
   2  * @fileoverview Rule to enforce spacing around colons of switch statements.
   3  * @author Toru Nagashima
   4  */
   5
   6 "use strict";
   7
   8 //------------------------------------------------------------------------------
   9 // Requirements
  10 //------------------------------------------------------------------------------
  11
  12 const astUtils = require("./utils/ast-utils");
  13
  14 //------------------------------------------------------------------------------
  15 // Rule Definition
  16 //------------------------------------------------------------------------------
  17
  18 /** @type {import('../shared/types').Rule} */
  19 module.exports = {
  20     meta: {
  21         type: "layout",
  22
  23         docs: {
  24             description: "enforce spacing around colons of switch statements",
  25             recommended: false,
  26             url: "https://eslint.org/docs/rules/switch-colon-spacing"
  27         },
  28
  29         schema: [
  30             {
  31                 type: "object",
  32                 properties: {
  33                     before: { type: "boolean", default: false },
  34                     after: { type: "boolean", default: true }
  35                 },
  36                 additionalProperties: false
  37             }
  38         ],
  39         fixable: "whitespace",
  40         messages: {
  41             expectedBefore: "Expected space(s) before this colon.",
  42             expectedAfter: "Expected space(s) after this colon.",
  43             unexpectedBefore: "Unexpected space(s) before this colon.",
  44             unexpectedAfter: "Unexpected space(s) after this colon."
  45         }
  46     },
  47
  48     create(context) {
  49         const sourceCode = context.getSourceCode();
  50         const options = context.options[0] || {};
  51         const beforeSpacing = options.before === true; // false by default
  52         const afterSpacing = options.after !== false; // true by default
  53
  54         /**
  55          * Check whether the spacing between the given 2 tokens is valid or not.
  56          * @param {Token} left The left token to check.
  57          * @param {Token} right The right token to check.
  58          * @param {boolean} expected The expected spacing to check. `true` if there should be a space.
  59          * @returns {boolean} `true` if the spacing between the tokens is valid.
  60          */
  61         function isValidSpacing(left, right, expected) {
  62             return (
  63                 astUtils.isClosingBraceToken(right) ||
  64                 !astUtils.isTokenOnSameLine(left, right) ||
  65                 sourceCode.isSpaceBetweenTokens(left, right) === expected
  66             );
  67         }
  68
  69         /**
  70          * Check whether comments exist between the given 2 tokens.
  71          * @param {Token} left The left token to check.
  72          * @param {Token} right The right token to check.
  73          * @returns {boolean} `true` if comments exist between the given 2 tokens.
  74          */
  75         function commentsExistBetween(left, right) {
  76             return sourceCode.getFirstTokenBetween(
  77                 left,
  78                 right,
  79                 {
  80                     includeComments: true,
  81                     filter: astUtils.isCommentToken
  82                 }
  83             ) !== null;
  84         }
  85
  86         /**
  87          * Fix the spacing between the given 2 tokens.
  88          * @param {RuleFixer} fixer The fixer to fix.
  89          * @param {Token} left The left token of fix range.
  90          * @param {Token} right The right token of fix range.
  91          * @param {boolean} spacing The spacing style. `true` if there should be a space.
  92          * @returns {Fix|null} The fix object.
  93          */
  94         function fix(fixer, left, right, spacing) {
  95             if (commentsExistBetween(left, right)) {
  96                 return null;
  97             }
  98             if (spacing) {
  99                 return fixer.insertTextAfter(left, " ");
 100             }
 101             return fixer.removeRange([left.range[1], right.range[0]]);
 102         }
 103
 104         return {
 105             SwitchCase(node) {
 106                 const colonToken = astUtils.getSwitchCaseColonToken(node, sourceCode);
 107                 const beforeToken = sourceCode.getTokenBefore(colonToken);
 108                 const afterToken = sourceCode.getTokenAfter(colonToken);
 109
 110                 if (!isValidSpacing(beforeToken, colonToken, beforeSpacing)) {
 111                     context.report({
 112                         node,
 113                         loc: colonToken.loc,
 114                         messageId: beforeSpacing ? "expectedBefore" : "unexpectedBefore",
 115                         fix: fixer => fix(fixer, beforeToken, colonToken, beforeSpacing)
 116                     });
 117                 }
 118                 if (!isValidSpacing(colonToken, afterToken, afterSpacing)) {
 119                     context.report({
 120                         node,
 121                         loc: colonToken.loc,
 122                         messageId: afterSpacing ? "expectedAfter" : "unexpectedAfter",
 123                         fix: fixer => fix(fixer, colonToken, afterToken, afterSpacing)
 124                     });
 125                 }
 126             }
 127         };
 128     }
 129 };