eslint/lib/rules/block-spacing.js

   1 /**
   2  * @fileoverview A rule to disallow or enforce spaces inside of single line blocks.
   3  * @author Toru Nagashima
   4  */
   5
   6 "use strict";
   7
   8 const util = require("./utils/ast-utils");
   9
  10 //------------------------------------------------------------------------------
  11 // Rule Definition
  12 //------------------------------------------------------------------------------
  13
  14 module.exports = {
  15     meta: {
  16         type: "layout",
  17
  18         docs: {
  19             description: "disallow or enforce spaces inside of blocks after opening block and before closing block",
  20             category: "Stylistic Issues",
  21             recommended: false,
  22             url: "https://eslint.org/docs/rules/block-spacing"
  23         },
  24
  25         fixable: "whitespace",
  26
  27         schema: [
  28             { enum: ["always", "never"] }
  29         ],
  30
  31         messages: {
  32             missing: "Requires a space {{location}} '{{token}}'.",
  33             extra: "Unexpected space(s) {{location}} '{{token}}'."
  34         }
  35     },
  36
  37     create(context) {
  38         const always = (context.options[0] !== "never"),
  39             messageId = always ? "missing" : "extra",
  40             sourceCode = context.getSourceCode();
  41
  42         /**
  43          * Gets the open brace token from a given node.
  44          * @param {ASTNode} node A BlockStatement/SwitchStatement node to get.
  45          * @returns {Token} The token of the open brace.
  46          */
  47         function getOpenBrace(node) {
  48             if (node.type === "SwitchStatement") {
  49                 if (node.cases.length > 0) {
  50                     return sourceCode.getTokenBefore(node.cases[0]);
  51                 }
  52                 return sourceCode.getLastToken(node, 1);
  53             }
  54             return sourceCode.getFirstToken(node);
  55         }
  56
  57         /**
  58          * Checks whether or not:
  59          *   - given tokens are on same line.
  60          *   - there is/isn't a space between given tokens.
  61          * @param {Token} left A token to check.
  62          * @param {Token} right The token which is next to `left`.
  63          * @returns {boolean}
  64          *    When the option is `"always"`, `true` if there are one or more spaces between given tokens.
  65          *    When the option is `"never"`, `true` if there are not any spaces between given tokens.
  66          *    If given tokens are not on same line, it's always `true`.
  67          */
  68         function isValid(left, right) {
  69             return (
  70                 !util.isTokenOnSameLine(left, right) ||
  71                 sourceCode.isSpaceBetweenTokens(left, right) === always
  72             );
  73         }
  74
  75         /**
  76          * Reports invalid spacing style inside braces.
  77          * @param {ASTNode} node A BlockStatement/SwitchStatement node to get.
  78          * @returns {void}
  79          */
  80         function checkSpacingInsideBraces(node) {
  81
  82             // Gets braces and the first/last token of content.
  83             const openBrace = getOpenBrace(node);
  84             const closeBrace = sourceCode.getLastToken(node);
  85             const firstToken = sourceCode.getTokenAfter(openBrace, { includeComments: true });
  86             const lastToken = sourceCode.getTokenBefore(closeBrace, { includeComments: true });
  87
  88             // Skip if the node is invalid or empty.
  89             if (openBrace.type !== "Punctuator" ||
  90                 openBrace.value !== "{" ||
  91                 closeBrace.type !== "Punctuator" ||
  92                 closeBrace.value !== "}" ||
  93                 firstToken === closeBrace
  94             ) {
  95                 return;
  96             }
  97
  98             // Skip line comments for option never
  99             if (!always && firstToken.type === "Line") {
 100                 return;
 101             }
 102
 103             // Check.
 104             if (!isValid(openBrace, firstToken)) {
 105                 let loc = openBrace.loc;
 106
 107                 if (messageId === "extra") {
 108                     loc = {
 109                         start: openBrace.loc.end,
 110                         end: firstToken.loc.start
 111                     };
 112                 }
 113
 114                 context.report({
 115                     node,
 116                     loc,
 117                     messageId,
 118                     data: {
 119                         location: "after",
 120                         token: openBrace.value
 121                     },
 122                     fix(fixer) {
 123                         if (always) {
 124                             return fixer.insertTextBefore(firstToken, " ");
 125                         }
 126
 127                         return fixer.removeRange([openBrace.range[1], firstToken.range[0]]);
 128                     }
 129                 });
 130             }
 131             if (!isValid(lastToken, closeBrace)) {
 132                 let loc = closeBrace.loc;
 133
 134                 if (messageId === "extra") {
 135                     loc = {
 136                         start: lastToken.loc.end,
 137                         end: closeBrace.loc.start
 138                     };
 139                 }
 140                 context.report({
 141                     node,
 142                     loc,
 143                     messageId,
 144                     data: {
 145                         location: "before",
 146                         token: closeBrace.value
 147                     },
 148                     fix(fixer) {
 149                         if (always) {
 150                             return fixer.insertTextAfter(lastToken, " ");
 151                         }
 152
 153                         return fixer.removeRange([lastToken.range[1], closeBrace.range[0]]);
 154                     }
 155                 });
 156             }
 157         }
 158
 159         return {
 160             BlockStatement: checkSpacingInsideBraces,
 161             SwitchStatement: checkSpacingInsideBraces
 162         };
 163     }
 164 };