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4 years ago
/**
* @fileoverview A rule to ensure whitespace before blocks.
* @author Mathias Schreck <https://github.com/lo1tuma>
*/
"use strict";
const astUtils = require("./utils/ast-utils");
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = {
meta: {
type: "layout",
docs: {
description: "enforce consistent spacing before blocks",
category: "Stylistic Issues",
recommended: false,
url: "https://eslint.org/docs/rules/space-before-blocks"
},
fixable: "whitespace",
schema: [
{
oneOf: [
{
enum: ["always", "never"]
},
{
type: "object",
properties: {
keywords: {
enum: ["always", "never", "off"]
},
functions: {
enum: ["always", "never", "off"]
},
classes: {
enum: ["always", "never", "off"]
}
},
additionalProperties: false
}
]
}
]
},
create(context) {
const config = context.options[0],
sourceCode = context.getSourceCode();
let alwaysFunctions = true,
alwaysKeywords = true,
alwaysClasses = true,
neverFunctions = false,
neverKeywords = false,
neverClasses = false;
if (typeof config === "object") {
alwaysFunctions = config.functions === "always";
alwaysKeywords = config.keywords === "always";
alwaysClasses = config.classes === "always";
neverFunctions = config.functions === "never";
neverKeywords = config.keywords === "never";
neverClasses = config.classes === "never";
} else if (config === "never") {
alwaysFunctions = false;
alwaysKeywords = false;
alwaysClasses = false;
neverFunctions = true;
neverKeywords = true;
neverClasses = true;
}
/**
* Checks whether or not a given token is an arrow operator (=>) or a keyword
* in order to avoid to conflict with `arrow-spacing` and `keyword-spacing`.
* @param {Token} token A token to check.
* @returns {boolean} `true` if the token is an arrow operator.
*/
function isConflicted(token) {
return (token.type === "Punctuator" && token.value === "=>") || token.type === "Keyword";
}
/**
* Checks the given BlockStatement node has a preceding space if it doesnt start on a new line.
* @param {ASTNode|Token} node The AST node of a BlockStatement.
* @returns {void} undefined.
*/
function checkPrecedingSpace(node) {
const precedingToken = sourceCode.getTokenBefore(node);
if (precedingToken && !isConflicted(precedingToken) && astUtils.isTokenOnSameLine(precedingToken, node)) {
const hasSpace = sourceCode.isSpaceBetweenTokens(precedingToken, node);
const parent = context.getAncestors().pop();
let requireSpace;
let requireNoSpace;
if (parent.type === "FunctionExpression" || parent.type === "FunctionDeclaration") {
requireSpace = alwaysFunctions;
requireNoSpace = neverFunctions;
} else if (node.type === "ClassBody") {
requireSpace = alwaysClasses;
requireNoSpace = neverClasses;
} else {
requireSpace = alwaysKeywords;
requireNoSpace = neverKeywords;
}
if (requireSpace && !hasSpace) {
context.report({
node,
message: "Missing space before opening brace.",
fix(fixer) {
return fixer.insertTextBefore(node, " ");
}
});
} else if (requireNoSpace && hasSpace) {
context.report({
node,
message: "Unexpected space before opening brace.",
fix(fixer) {
return fixer.removeRange([precedingToken.range[1], node.range[0]]);
}
});
}
}
}
/**
* Checks if the CaseBlock of an given SwitchStatement node has a preceding space.
* @param {ASTNode} node The node of a SwitchStatement.
* @returns {void} undefined.
*/
function checkSpaceBeforeCaseBlock(node) {
const cases = node.cases;
let openingBrace;
if (cases.length > 0) {
openingBrace = sourceCode.getTokenBefore(cases[0]);
} else {
openingBrace = sourceCode.getLastToken(node, 1);
}
checkPrecedingSpace(openingBrace);
}
return {
BlockStatement: checkPrecedingSpace,
ClassBody: checkPrecedingSpace,
SwitchStatement: checkSpaceBeforeCaseBlock
};
}
};