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/**
* @fileoverview Rule to flag missing semicolons.
* @author Nicholas C. Zakas
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const FixTracker = require("./utils/fix-tracker");
const astUtils = require("./utils/ast-utils");
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = {
meta: {
type: "layout",
docs: {
description: "require or disallow semicolons instead of ASI",
category: "Stylistic Issues",
recommended: false,
url: "https://eslint.org/docs/rules/semi"
},
fixable: "code",
schema: {
anyOf: [
{
type: "array",
items: [
{
enum: ["never"]
},
{
type: "object",
properties: {
beforeStatementContinuationChars: {
enum: ["always", "any", "never"]
}
},
additionalProperties: false
}
],
minItems: 0,
maxItems: 2
},
{
type: "array",
items: [
{
enum: ["always"]
},
{
type: "object",
properties: {
omitLastInOneLineBlock: { type: "boolean" }
},
additionalProperties: false
}
],
minItems: 0,
maxItems: 2
}
]
}
},
create(context) {
const OPT_OUT_PATTERN = /^[-[(/+`]/u; // One of [(/+-`
const options = context.options[1];
const never = context.options[0] === "never";
const exceptOneLine = Boolean(options && options.omitLastInOneLineBlock);
const beforeStatementContinuationChars = options && options.beforeStatementContinuationChars || "any";
const sourceCode = context.getSourceCode();
//--------------------------------------------------------------------------
// Helpers
//--------------------------------------------------------------------------
/**
* Reports a semicolon error with appropriate location and message.
* @param {ASTNode} node The node with an extra or missing semicolon.
* @param {boolean} missing True if the semicolon is missing.
* @returns {void}
*/
function report(node, missing) {
const lastToken = sourceCode.getLastToken(node);
let message,
fix,
loc;
if (!missing) {
message = "Missing semicolon.";
loc = {
start: lastToken.loc.end,
end: astUtils.getNextLocation(sourceCode, lastToken.loc.end)
};
fix = function(fixer) {
return fixer.insertTextAfter(lastToken, ";");
};
} else {
message = "Extra semicolon.";
loc = lastToken.loc;
fix = function(fixer) {
/*
* Expand the replacement range to include the surrounding
* tokens to avoid conflicting with no-extra-semi.
* https://github.com/eslint/eslint/issues/7928
*/
return new FixTracker(fixer, sourceCode)
.retainSurroundingTokens(lastToken)
.remove(lastToken);
};
}
context.report({
node,
loc,
message,
fix
});
}
/**
* Check whether a given semicolon token is redandant.
* @param {Token} semiToken A semicolon token to check.
* @returns {boolean} `true` if the next token is `;` or `}`.
*/
function isRedundantSemi(semiToken) {
const nextToken = sourceCode.getTokenAfter(semiToken);
return (
!nextToken ||
astUtils.isClosingBraceToken(nextToken) ||
astUtils.isSemicolonToken(nextToken)
);
}
/**
* Check whether a given token is the closing brace of an arrow function.
* @param {Token} lastToken A token to check.
* @returns {boolean} `true` if the token is the closing brace of an arrow function.
*/
function isEndOfArrowBlock(lastToken) {
if (!astUtils.isClosingBraceToken(lastToken)) {
return false;
}
const node = sourceCode.getNodeByRangeIndex(lastToken.range[0]);
return (
node.type === "BlockStatement" &&
node.parent.type === "ArrowFunctionExpression"
);
}
/**
* Check whether a given node is on the same line with the next token.
* @param {Node} node A statement node to check.
* @returns {boolean} `true` if the node is on the same line with the next token.
*/
function isOnSameLineWithNextToken(node) {
const prevToken = sourceCode.getLastToken(node, 1);
const nextToken = sourceCode.getTokenAfter(node);
return !!nextToken && astUtils.isTokenOnSameLine(prevToken, nextToken);
}
/**
* Check whether a given node can connect the next line if the next line is unreliable.
* @param {Node} node A statement node to check.
* @returns {boolean} `true` if the node can connect the next line.
*/
function maybeAsiHazardAfter(node) {
const t = node.type;
if (t === "DoWhileStatement" ||
t === "BreakStatement" ||
t === "ContinueStatement" ||
t === "DebuggerStatement" ||
t === "ImportDeclaration" ||
t === "ExportAllDeclaration"
) {
return false;
}
if (t === "ReturnStatement") {
return Boolean(node.argument);
}
if (t === "ExportNamedDeclaration") {
return Boolean(node.declaration);
}
if (isEndOfArrowBlock(sourceCode.getLastToken(node, 1))) {
return false;
}
return true;
}
/**
* Check whether a given token can connect the previous statement.
* @param {Token} token A token to check.
* @returns {boolean} `true` if the token is one of `[`, `(`, `/`, `+`, `-`, ```, `++`, and `--`.
*/
function maybeAsiHazardBefore(token) {
return (
Boolean(token) &&
OPT_OUT_PATTERN.test(token.value) &&
token.value !== "++" &&
token.value !== "--"
);
}
/**
* Check if the semicolon of a given node is unnecessary, only true if:
* - next token is a valid statement divider (`;` or `}`).
* - next token is on a new line and the node is not connectable to the new line.
* @param {Node} node A statement node to check.
* @returns {boolean} whether the semicolon is unnecessary.
*/
function canRemoveSemicolon(node) {
if (isRedundantSemi(sourceCode.getLastToken(node))) {
return true; // `;;` or `;}`
}
if (isOnSameLineWithNextToken(node)) {
return false; // One liner.
}
if (beforeStatementContinuationChars === "never" && !maybeAsiHazardAfter(node)) {
return true; // ASI works. This statement doesn't connect to the next.
}
if (!maybeAsiHazardBefore(sourceCode.getTokenAfter(node))) {
return true; // ASI works. The next token doesn't connect to this statement.
}
return false;
}
/**
* Checks a node to see if it's in a one-liner block statement.
* @param {ASTNode} node The node to check.
* @returns {boolean} whether the node is in a one-liner block statement.
*/
function isOneLinerBlock(node) {
const parent = node.parent;
const nextToken = sourceCode.getTokenAfter(node);
if (!nextToken || nextToken.value !== "}") {
return false;
}
return (
!!parent &&
parent.type === "BlockStatement" &&
parent.loc.start.line === parent.loc.end.line
);
}
/**
* Checks a node to see if it's followed by a semicolon.
* @param {ASTNode} node The node to check.
* @returns {void}
*/
function checkForSemicolon(node) {
const isSemi = astUtils.isSemicolonToken(sourceCode.getLastToken(node));
if (never) {
if (isSemi && canRemoveSemicolon(node)) {
report(node, true);
} else if (!isSemi && beforeStatementContinuationChars === "always" && maybeAsiHazardBefore(sourceCode.getTokenAfter(node))) {
report(node);
}
} else {
const oneLinerBlock = (exceptOneLine && isOneLinerBlock(node));
if (isSemi && oneLinerBlock) {
report(node, true);
} else if (!isSemi && !oneLinerBlock) {
report(node);
}
}
}
/**
* Checks to see if there's a semicolon after a variable declaration.
* @param {ASTNode} node The node to check.
* @returns {void}
*/
function checkForSemicolonForVariableDeclaration(node) {
const parent = node.parent;
if ((parent.type !== "ForStatement" || parent.init !== node) &&
(!/^For(?:In|Of)Statement/u.test(parent.type) || parent.left !== node)
) {
checkForSemicolon(node);
}
}
//--------------------------------------------------------------------------
// Public API
//--------------------------------------------------------------------------
return {
VariableDeclaration: checkForSemicolonForVariableDeclaration,
ExpressionStatement: checkForSemicolon,
ReturnStatement: checkForSemicolon,
ThrowStatement: checkForSemicolon,
DoWhileStatement: checkForSemicolon,
DebuggerStatement: checkForSemicolon,
BreakStatement: checkForSemicolon,
ContinueStatement: checkForSemicolon,
ImportDeclaration: checkForSemicolon,
ExportAllDeclaration: checkForSemicolon,
ExportNamedDeclaration(node) {
if (!node.declaration) {
checkForSemicolon(node);
}
},
ExportDefaultDeclaration(node) {
if (!/(?:Class|Function)Declaration/u.test(node.declaration.type)) {
checkForSemicolon(node);
}
}
};
}
};