nonblock-statement-body-position.js
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/**
* @fileoverview enforce the location of single-line statements
* @author Teddy Katz
*/
"use strict";
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
const POSITION_SCHEMA = { enum: ["beside", "below", "any"] };
/** @type {import('../shared/types').Rule} */
module.exports = {
meta: {
type: "layout",
docs: {
description: "Enforce the location of single-line statements",
recommended: false,
url: "https://eslint.org/docs/rules/nonblock-statement-body-position"
},
fixable: "whitespace",
schema: [
POSITION_SCHEMA,
{
properties: {
overrides: {
properties: {
if: POSITION_SCHEMA,
else: POSITION_SCHEMA,
while: POSITION_SCHEMA,
do: POSITION_SCHEMA,
for: POSITION_SCHEMA
},
additionalProperties: false
}
},
additionalProperties: false
}
],
messages: {
expectNoLinebreak: "Expected no linebreak before this statement.",
expectLinebreak: "Expected a linebreak before this statement."
}
},
create(context) {
const sourceCode = context.getSourceCode();
//----------------------------------------------------------------------
// Helpers
//----------------------------------------------------------------------
/**
* Gets the applicable preference for a particular keyword
* @param {string} keywordName The name of a keyword, e.g. 'if'
* @returns {string} The applicable option for the keyword, e.g. 'beside'
*/
function getOption(keywordName) {
return context.options[1] && context.options[1].overrides && context.options[1].overrides[keywordName] ||
context.options[0] ||
"beside";
}
/**
* Validates the location of a single-line statement
* @param {ASTNode} node The single-line statement
* @param {string} keywordName The applicable keyword name for the single-line statement
* @returns {void}
*/
function validateStatement(node, keywordName) {
const option = getOption(keywordName);
if (node.type === "BlockStatement" || option === "any") {
return;
}
const tokenBefore = sourceCode.getTokenBefore(node);
if (tokenBefore.loc.end.line === node.loc.start.line && option === "below") {
context.report({
node,
messageId: "expectLinebreak",
fix: fixer => fixer.insertTextBefore(node, "\n")
});
} else if (tokenBefore.loc.end.line !== node.loc.start.line && option === "beside") {
context.report({
node,
messageId: "expectNoLinebreak",
fix(fixer) {
if (sourceCode.getText().slice(tokenBefore.range[1], node.range[0]).trim()) {
return null;
}
return fixer.replaceTextRange([tokenBefore.range[1], node.range[0]], " ");
}
});
}
}
//----------------------------------------------------------------------
// Public
//----------------------------------------------------------------------
return {
IfStatement(node) {
validateStatement(node.consequent, "if");
// Check the `else` node, but don't check 'else if' statements.
if (node.alternate && node.alternate.type !== "IfStatement") {
validateStatement(node.alternate, "else");
}
},
WhileStatement: node => validateStatement(node.body, "while"),
DoWhileStatement: node => validateStatement(node.body, "do"),
ForStatement: node => validateStatement(node.body, "for"),
ForInStatement: node => validateStatement(node.body, "for"),
ForOfStatement: node => validateStatement(node.body, "for")
};
}
};