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/**
* @fileoverview Rule to disallow use of the `RegExp` constructor in favor of regular expression literals
* @author Milos Djermanovic
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const astUtils = require("./utils/ast-utils");
const {
CALL,
CONSTRUCT,
ReferenceTracker,
findVariable,
} = require("@eslint-community/eslint-utils");
const {
RegExpValidator,
visitRegExpAST,
RegExpParser,
} = require("@eslint-community/regexpp");
const { canTokensBeAdjacent } = require("./utils/ast-utils");
const { REGEXPP_LATEST_ECMA_VERSION } = require("./utils/regular-expressions");
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
/**
* Determines whether the given node is a string literal.
* @param {ASTNode} node Node to check.
* @returns {boolean} True if the node is a string literal.
*/
function isStringLiteral(node) {
return node.type === "Literal" && typeof node.value === "string";
}
/**
* Determines whether the given node is a regex literal.
* @param {ASTNode} node Node to check.
* @returns {boolean} True if the node is a regex literal.
*/
function isRegexLiteral(node) {
return node.type === "Literal" && Object.hasOwn(node, "regex");
}
const validPrecedingTokens = new Set([
"(",
";",
"[",
",",
"=",
"+",
"*",
"-",
"?",
"~",
"%",
"**",
"!",
"typeof",
"instanceof",
"&&",
"||",
"??",
"return",
"...",
"delete",
"void",
"in",
"<",
">",
"<=",
">=",
"==",
"===",
"!=",
"!==",
"<<",
">>",
">>>",
"&",
"|",
"^",
":",
"{",
"=>",
"*=",
"<<=",
">>=",
">>>=",
"^=",
"|=",
"&=",
"??=",
"||=",
"&&=",
"**=",
"+=",
"-=",
"/=",
"%=",
"/",
"do",
"break",
"continue",
"debugger",
"case",
"throw",
]);
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
/** @type {import('../types').Rule.RuleModule} */
module.exports = {
meta: {
type: "suggestion",
defaultOptions: [
{
disallowRedundantWrapping: false,
},
],
docs: {
description:
"Disallow use of the `RegExp` constructor in favor of regular expression literals",
recommended: false,
url: "https://eslint.org/docs/latest/rules/prefer-regex-literals",
},
hasSuggestions: true,
schema: [
{
type: "object",
properties: {
disallowRedundantWrapping: {
type: "boolean",
},
},
additionalProperties: false,
},
],
messages: {
unexpectedRegExp:
"Use a regular expression literal instead of the 'RegExp' constructor.",
replaceWithLiteral:
"Replace with an equivalent regular expression literal.",
replaceWithLiteralAndFlags:
"Replace with an equivalent regular expression literal with flags '{{ flags }}'.",
replaceWithIntendedLiteralAndFlags:
"Replace with a regular expression literal with flags '{{ flags }}'.",
unexpectedRedundantRegExp:
"Regular expression literal is unnecessarily wrapped within a 'RegExp' constructor.",
unexpectedRedundantRegExpWithFlags:
"Use regular expression literal with flags instead of the 'RegExp' constructor.",
},
},
create(context) {
const [{ disallowRedundantWrapping }] = context.options;
const sourceCode = context.sourceCode;
/**
* Determines whether the given identifier node is a reference to a global variable.
* @param {ASTNode} node `Identifier` node to check.
* @returns {boolean} True if the identifier is a reference to a global variable.
*/
function isGlobalReference(node) {
const scope = sourceCode.getScope(node);
const variable = findVariable(scope, node);
return (
variable !== null &&
variable.scope.type === "global" &&
variable.defs.length === 0
);
}
/**
* Determines whether the given node is a String.raw`` tagged template expression
* with a static template literal.
* @param {ASTNode} node Node to check.
* @returns {boolean} True if the node is String.raw`` with a static template.
*/
function isStringRawTaggedStaticTemplateLiteral(node) {
return (
node.type === "TaggedTemplateExpression" &&
astUtils.isSpecificMemberAccess(node.tag, "String", "raw") &&
isGlobalReference(
astUtils.skipChainExpression(node.tag).object,
) &&
astUtils.isStaticTemplateLiteral(node.quasi)
);
}
/**
* Gets the value of a string
* @param {ASTNode} node The node to get the string of.
* @returns {string|null} The value of the node.
*/
function getStringValue(node) {
if (isStringLiteral(node)) {
return node.value;
}
if (astUtils.isStaticTemplateLiteral(node)) {
return node.quasis[0].value.cooked;
}
if (isStringRawTaggedStaticTemplateLiteral(node)) {
return node.quasi.quasis[0].value.raw;
}
return null;
}
/**
* Determines whether the given node is considered to be a static string by the logic of this rule.
* @param {ASTNode} node Node to check.
* @returns {boolean} True if the node is a static string.
*/
function isStaticString(node) {
return (
isStringLiteral(node) ||
astUtils.isStaticTemplateLiteral(node) ||
isStringRawTaggedStaticTemplateLiteral(node)
);
}
/**
* Determines whether the relevant arguments of the given are all static string literals.
* @param {ASTNode} node Node to check.
* @returns {boolean} True if all arguments are static strings.
*/
function hasOnlyStaticStringArguments(node) {
const args = node.arguments;
if (
(args.length === 1 || args.length === 2) &&
args.every(isStaticString)
) {
return true;
}
return false;
}
/**
* Determines whether the arguments of the given node indicate that a regex literal is unnecessarily wrapped.
* @param {ASTNode} node Node to check.
* @returns {boolean} True if the node already contains a regex literal argument.
*/
function isUnnecessarilyWrappedRegexLiteral(node) {
const args = node.arguments;
if (args.length === 1 && isRegexLiteral(args[0])) {
return true;
}
if (
args.length === 2 &&
isRegexLiteral(args[0]) &&
isStaticString(args[1])
) {
return true;
}
return false;
}
/**
* Returns a ecmaVersion compatible for regexpp.
* @param {number} ecmaVersion The ecmaVersion to convert.
* @returns {import("@eslint-community/regexpp/ecma-versions").EcmaVersion} The resulting ecmaVersion compatible for regexpp.
*/
function getRegexppEcmaVersion(ecmaVersion) {
if (ecmaVersion <= 5) {
return 5;
}
return Math.min(ecmaVersion, REGEXPP_LATEST_ECMA_VERSION);
}
const regexppEcmaVersion = getRegexppEcmaVersion(
context.languageOptions.ecmaVersion,
);
/**
* Makes a character escaped or else returns null.
* @param {string} character The character to escape.
* @returns {string} The resulting escaped character.
*/
function resolveEscapes(character) {
switch (character) {
case "\n":
case "\\\n":
return "\\n";
case "\r":
case "\\\r":
return "\\r";
case "\t":
case "\\\t":
return "\\t";
case "\v":
case "\\\v":
return "\\v";
case "\f":
case "\\\f":
return "\\f";
case "/":
return "\\/";
default:
return null;
}
}
/**
* Checks whether the given regex and flags are valid for the ecma version or not.
* @param {string} pattern The regex pattern to check.
* @param {string | undefined} flags The regex flags to check.
* @returns {boolean} True if the given regex pattern and flags are valid for the ecma version.
*/
function isValidRegexForEcmaVersion(pattern, flags) {
const validator = new RegExpValidator({
ecmaVersion: regexppEcmaVersion,
});
try {
validator.validatePattern(pattern, 0, pattern.length, {
unicode: flags ? flags.includes("u") : false,
unicodeSets: flags ? flags.includes("v") : false,
});
if (flags) {
validator.validateFlags(flags);
}
return true;
} catch {
return false;
}
}
/**
* Checks whether two given regex flags contain the same flags or not.
* @param {string} flagsA The regex flags.
* @param {string} flagsB The regex flags.
* @returns {boolean} True if two regex flags contain same flags.
*/
function areFlagsEqual(flagsA, flagsB) {
return [...flagsA].sort().join("") === [...flagsB].sort().join("");
}
/**
* Merges two regex flags.
* @param {string} flagsA The regex flags.
* @param {string} flagsB The regex flags.
* @returns {string} The merged regex flags.
*/
function mergeRegexFlags(flagsA, flagsB) {
const flagsSet = new Set([...flagsA, ...flagsB]);
return [...flagsSet].join("");
}
/**
* Checks whether a give node can be fixed to the given regex pattern and flags.
* @param {ASTNode} node The node to check.
* @param {string} pattern The regex pattern to check.
* @param {string} flags The regex flags
* @returns {boolean} True if a node can be fixed to the given regex pattern and flags.
*/
function canFixTo(node, pattern, flags) {
const tokenBefore = sourceCode.getTokenBefore(node);
return (
sourceCode.getCommentsInside(node).length === 0 &&
(!tokenBefore || validPrecedingTokens.has(tokenBefore.value)) &&
isValidRegexForEcmaVersion(pattern, flags)
);
}
/**
* Returns a safe output code considering the before and after tokens.
* @param {ASTNode} node The regex node.
* @param {string} newRegExpValue The new regex expression value.
* @returns {string} The output code.
*/
function getSafeOutput(node, newRegExpValue) {
const tokenBefore = sourceCode.getTokenBefore(node);
const tokenAfter = sourceCode.getTokenAfter(node);
return (
(tokenBefore &&
!canTokensBeAdjacent(tokenBefore, newRegExpValue) &&
tokenBefore.range[1] === node.range[0]
? " "
: "") +
newRegExpValue +
(tokenAfter &&
!canTokensBeAdjacent(newRegExpValue, tokenAfter) &&
node.range[1] === tokenAfter.range[0]
? " "
: "")
);
}
return {
Program(node) {
const scope = sourceCode.getScope(node);
const tracker = new ReferenceTracker(scope);
const traceMap = {
RegExp: {
[CALL]: true,
[CONSTRUCT]: true,
},
};
for (const { node: refNode } of tracker.iterateGlobalReferences(
traceMap,
)) {
if (
disallowRedundantWrapping &&
isUnnecessarilyWrappedRegexLiteral(refNode)
) {
const regexNode = refNode.arguments[0];
if (refNode.arguments.length === 2) {
const suggests = [];
const argFlags =
getStringValue(refNode.arguments[1]) || "";
if (
canFixTo(
refNode,
regexNode.regex.pattern,
argFlags,
)
) {
suggests.push({
messageId: "replaceWithLiteralAndFlags",
pattern: regexNode.regex.pattern,
flags: argFlags,
});
}
const literalFlags = regexNode.regex.flags || "";
const mergedFlags = mergeRegexFlags(
literalFlags,
argFlags,
);
if (
!areFlagsEqual(mergedFlags, argFlags) &&
canFixTo(
refNode,
regexNode.regex.pattern,
mergedFlags,
)
) {
suggests.push({
messageId:
"replaceWithIntendedLiteralAndFlags",
pattern: regexNode.regex.pattern,
flags: mergedFlags,
});
}
context.report({
node: refNode,
messageId: "unexpectedRedundantRegExpWithFlags",
suggest: suggests.map(
({ flags, pattern, messageId }) => ({
messageId,
data: {
flags,
},
fix(fixer) {
return fixer.replaceText(
refNode,
getSafeOutput(
refNode,
`/${pattern}/${flags}`,
),
);
},
}),
),
});
} else {
const outputs = [];
if (
canFixTo(
refNode,
regexNode.regex.pattern,
regexNode.regex.flags,
)
) {
outputs.push(sourceCode.getText(regexNode));
}
context.report({
node: refNode,
messageId: "unexpectedRedundantRegExp",
suggest: outputs.map(output => ({
messageId: "replaceWithLiteral",
fix(fixer) {
return fixer.replaceText(
refNode,
getSafeOutput(refNode, output),
);
},
})),
});
}
} else if (hasOnlyStaticStringArguments(refNode)) {
let regexContent = getStringValue(refNode.arguments[0]);
let noFix = false;
let flags;
if (refNode.arguments[1]) {
flags = getStringValue(refNode.arguments[1]);
}
if (!canFixTo(refNode, regexContent, flags)) {
noFix = true;
}
if (
!/^[-a-zA-Z0-9\\[\](){} \t\r\n\v\f!@#$%^&*+^_=/~`.><?,'"|:;]*$/u.test(
regexContent,
)
) {
noFix = true;
}
if (regexContent && !noFix) {
let charIncrease = 0;
const ast = new RegExpParser({
ecmaVersion: regexppEcmaVersion,
}).parsePattern(
regexContent,
0,
regexContent.length,
{
unicode: flags
? flags.includes("u")
: false,
unicodeSets: flags
? flags.includes("v")
: false,
},
);
visitRegExpAST(ast, {
onCharacterEnter(characterNode) {
const escaped = resolveEscapes(
characterNode.raw,
);
if (escaped) {
regexContent =
regexContent.slice(
0,
characterNode.start +
charIncrease,
) +
escaped +
regexContent.slice(
characterNode.end +
charIncrease,
);
if (characterNode.raw.length === 1) {
charIncrease += 1;
}
}
},
});
}
const newRegExpValue = `/${regexContent || "(?:)"}/${flags || ""}`;
context.report({
node: refNode,
messageId: "unexpectedRegExp",
suggest: noFix
? []
: [
{
messageId: "replaceWithLiteral",
fix(fixer) {
return fixer.replaceText(
refNode,
getSafeOutput(
refNode,
newRegExpValue,
),
);
},
},
],
});
}
}
},
};
},
};
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