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- /**
- * @fileoverview Rule to validate spacing before function paren.
- * @author Mathias Schreck <https://github.com/lo1tuma>
- */
- "use strict";
- //------------------------------------------------------------------------------
- // Requirements
- //------------------------------------------------------------------------------
- const astUtils = require("./utils/ast-utils");
- //------------------------------------------------------------------------------
- // Rule Definition
- //------------------------------------------------------------------------------
- /** @type {import('../shared/types').Rule} */
- module.exports = {
- meta: {
- type: "layout",
- docs: {
- description: "Enforce consistent spacing before `function` definition opening parenthesis",
- recommended: false,
- url: "https://eslint.org/docs/rules/space-before-function-paren"
- },
- fixable: "whitespace",
- schema: [
- {
- oneOf: [
- {
- enum: ["always", "never"]
- },
- {
- type: "object",
- properties: {
- anonymous: {
- enum: ["always", "never", "ignore"]
- },
- named: {
- enum: ["always", "never", "ignore"]
- },
- asyncArrow: {
- enum: ["always", "never", "ignore"]
- }
- },
- additionalProperties: false
- }
- ]
- }
- ],
- messages: {
- unexpectedSpace: "Unexpected space before function parentheses.",
- missingSpace: "Missing space before function parentheses."
- }
- },
- create(context) {
- const sourceCode = context.getSourceCode();
- const baseConfig = typeof context.options[0] === "string" ? context.options[0] : "always";
- const overrideConfig = typeof context.options[0] === "object" ? context.options[0] : {};
- /**
- * Determines whether a function has a name.
- * @param {ASTNode} node The function node.
- * @returns {boolean} Whether the function has a name.
- */
- function isNamedFunction(node) {
- if (node.id) {
- return true;
- }
- const parent = node.parent;
- return parent.type === "MethodDefinition" ||
- (parent.type === "Property" &&
- (
- parent.kind === "get" ||
- parent.kind === "set" ||
- parent.method
- )
- );
- }
- /**
- * Gets the config for a given function
- * @param {ASTNode} node The function node
- * @returns {string} "always", "never", or "ignore"
- */
- function getConfigForFunction(node) {
- if (node.type === "ArrowFunctionExpression") {
- // Always ignore non-async functions and arrow functions without parens, e.g. async foo => bar
- if (node.async && astUtils.isOpeningParenToken(sourceCode.getFirstToken(node, { skip: 1 }))) {
- return overrideConfig.asyncArrow || baseConfig;
- }
- } else if (isNamedFunction(node)) {
- return overrideConfig.named || baseConfig;
- // `generator-star-spacing` should warn anonymous generators. E.g. `function* () {}`
- } else if (!node.generator) {
- return overrideConfig.anonymous || baseConfig;
- }
- return "ignore";
- }
- /**
- * Checks the parens of a function node
- * @param {ASTNode} node A function node
- * @returns {void}
- */
- function checkFunction(node) {
- const functionConfig = getConfigForFunction(node);
- if (functionConfig === "ignore") {
- return;
- }
- const rightToken = sourceCode.getFirstToken(node, astUtils.isOpeningParenToken);
- const leftToken = sourceCode.getTokenBefore(rightToken);
- const hasSpacing = sourceCode.isSpaceBetweenTokens(leftToken, rightToken);
- if (hasSpacing && functionConfig === "never") {
- context.report({
- node,
- loc: {
- start: leftToken.loc.end,
- end: rightToken.loc.start
- },
- messageId: "unexpectedSpace",
- fix(fixer) {
- const comments = sourceCode.getCommentsBefore(rightToken);
- // Don't fix anything if there's a single line comment between the left and the right token
- if (comments.some(comment => comment.type === "Line")) {
- return null;
- }
- return fixer.replaceTextRange(
- [leftToken.range[1], rightToken.range[0]],
- comments.reduce((text, comment) => text + sourceCode.getText(comment), "")
- );
- }
- });
- } else if (!hasSpacing && functionConfig === "always") {
- context.report({
- node,
- loc: rightToken.loc,
- messageId: "missingSpace",
- fix: fixer => fixer.insertTextAfter(leftToken, " ")
- });
- }
- }
- return {
- ArrowFunctionExpression: checkFunction,
- FunctionDeclaration: checkFunction,
- FunctionExpression: checkFunction
- };
- }
- };
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