space-before-blocks.js 5.6 KB

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  1. /**
  2. * @fileoverview A rule to ensure whitespace before blocks.
  3. * @author Mathias Schreck <https://github.com/lo1tuma>
  4. */
  5. "use strict";
  6. const astUtils = require("./utils/ast-utils");
  7. //------------------------------------------------------------------------------
  8. // Rule Definition
  9. //------------------------------------------------------------------------------
  10. module.exports = {
  11. meta: {
  12. type: "layout",
  13. docs: {
  14. description: "enforce consistent spacing before blocks",
  15. category: "Stylistic Issues",
  16. recommended: false,
  17. url: "https://eslint.org/docs/rules/space-before-blocks"
  18. },
  19. fixable: "whitespace",
  20. schema: [
  21. {
  22. oneOf: [
  23. {
  24. enum: ["always", "never"]
  25. },
  26. {
  27. type: "object",
  28. properties: {
  29. keywords: {
  30. enum: ["always", "never", "off"]
  31. },
  32. functions: {
  33. enum: ["always", "never", "off"]
  34. },
  35. classes: {
  36. enum: ["always", "never", "off"]
  37. }
  38. },
  39. additionalProperties: false
  40. }
  41. ]
  42. }
  43. ]
  44. },
  45. create(context) {
  46. const config = context.options[0],
  47. sourceCode = context.getSourceCode();
  48. let alwaysFunctions = true,
  49. alwaysKeywords = true,
  50. alwaysClasses = true,
  51. neverFunctions = false,
  52. neverKeywords = false,
  53. neverClasses = false;
  54. if (typeof config === "object") {
  55. alwaysFunctions = config.functions === "always";
  56. alwaysKeywords = config.keywords === "always";
  57. alwaysClasses = config.classes === "always";
  58. neverFunctions = config.functions === "never";
  59. neverKeywords = config.keywords === "never";
  60. neverClasses = config.classes === "never";
  61. } else if (config === "never") {
  62. alwaysFunctions = false;
  63. alwaysKeywords = false;
  64. alwaysClasses = false;
  65. neverFunctions = true;
  66. neverKeywords = true;
  67. neverClasses = true;
  68. }
  69. /**
  70. * Checks whether or not a given token is an arrow operator (=>) or a keyword
  71. * in order to avoid to conflict with `arrow-spacing` and `keyword-spacing`.
  72. * @param {Token} token A token to check.
  73. * @returns {boolean} `true` if the token is an arrow operator.
  74. */
  75. function isConflicted(token) {
  76. return (token.type === "Punctuator" && token.value === "=>") || token.type === "Keyword";
  77. }
  78. /**
  79. * Checks the given BlockStatement node has a preceding space if it doesn’t start on a new line.
  80. * @param {ASTNode|Token} node The AST node of a BlockStatement.
  81. * @returns {void} undefined.
  82. */
  83. function checkPrecedingSpace(node) {
  84. const precedingToken = sourceCode.getTokenBefore(node);
  85. if (precedingToken && !isConflicted(precedingToken) && astUtils.isTokenOnSameLine(precedingToken, node)) {
  86. const hasSpace = sourceCode.isSpaceBetweenTokens(precedingToken, node);
  87. const parent = context.getAncestors().pop();
  88. let requireSpace;
  89. let requireNoSpace;
  90. if (parent.type === "FunctionExpression" || parent.type === "FunctionDeclaration") {
  91. requireSpace = alwaysFunctions;
  92. requireNoSpace = neverFunctions;
  93. } else if (node.type === "ClassBody") {
  94. requireSpace = alwaysClasses;
  95. requireNoSpace = neverClasses;
  96. } else {
  97. requireSpace = alwaysKeywords;
  98. requireNoSpace = neverKeywords;
  99. }
  100. if (requireSpace && !hasSpace) {
  101. context.report({
  102. node,
  103. message: "Missing space before opening brace.",
  104. fix(fixer) {
  105. return fixer.insertTextBefore(node, " ");
  106. }
  107. });
  108. } else if (requireNoSpace && hasSpace) {
  109. context.report({
  110. node,
  111. message: "Unexpected space before opening brace.",
  112. fix(fixer) {
  113. return fixer.removeRange([precedingToken.range[1], node.range[0]]);
  114. }
  115. });
  116. }
  117. }
  118. }
  119. /**
  120. * Checks if the CaseBlock of an given SwitchStatement node has a preceding space.
  121. * @param {ASTNode} node The node of a SwitchStatement.
  122. * @returns {void} undefined.
  123. */
  124. function checkSpaceBeforeCaseBlock(node) {
  125. const cases = node.cases;
  126. let openingBrace;
  127. if (cases.length > 0) {
  128. openingBrace = sourceCode.getTokenBefore(cases[0]);
  129. } else {
  130. openingBrace = sourceCode.getLastToken(node, 1);
  131. }
  132. checkPrecedingSpace(openingBrace);
  133. }
  134. return {
  135. BlockStatement: checkPrecedingSpace,
  136. ClassBody: checkPrecedingSpace,
  137. SwitchStatement: checkSpaceBeforeCaseBlock
  138. };
  139. }
  140. };