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/**
* @fileoverview Rule to disallow `\8` and `\9` escape sequences in string literals.
* @author Milos Djermanovic
*/
"use strict";
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
const QUICK_TEST_REGEX = /\\[89]/u;
/**
* Returns unicode escape sequence that represents the given character.
* @param {string} character A single code unit.
* @returns {string} "\uXXXX" sequence.
*/
function getUnicodeEscape(character) {
return `\\u${character.charCodeAt(0).toString(16).padStart(4, "0")}`;
}
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
/** @type {import('../shared/types').Rule} */
module.exports = {
meta: {
type: "suggestion",
docs: {
description: "Disallow `\\8` and `\\9` escape sequences in string literals",
recommended: true,
url: "https://eslint.org/docs/latest/rules/no-nonoctal-decimal-escape"
},
hasSuggestions: true,
schema: [],
messages: {
decimalEscape: "Don't use '{{decimalEscape}}' escape sequence.",
// suggestions
refactor: "Replace '{{original}}' with '{{replacement}}'. This maintains the current functionality.",
escapeBackslash: "Replace '{{original}}' with '{{replacement}}' to include the actual backslash character."
}
},
create(context) {
const sourceCode = context.sourceCode;
/**
* Creates a new Suggestion object.
* @param {string} messageId "refactor" or "escapeBackslash".
* @param {int[]} range The range to replace.
* @param {string} replacement New text for the range.
* @returns {Object} Suggestion
*/
function createSuggestion(messageId, range, replacement) {
return {
messageId,
data: {
original: sourceCode.getText().slice(...range),
replacement
},
fix(fixer) {
return fixer.replaceTextRange(range, replacement);
}
};
}
return {
Literal(node) {
if (typeof node.value !== "string") {
return;
}
if (!QUICK_TEST_REGEX.test(node.raw)) {
return;
}
const regex = /(?:[^\\]|(?<previousEscape>\\.))*?(?<decimalEscape>\\[89])/suy;
let match;
while ((match = regex.exec(node.raw))) {
const { previousEscape, decimalEscape } = match.groups;
const decimalEscapeRangeEnd = node.range[0] + match.index + match[0].length;
const decimalEscapeRangeStart = decimalEscapeRangeEnd - decimalEscape.length;
const decimalEscapeRange = [decimalEscapeRangeStart, decimalEscapeRangeEnd];
const suggest = [];
// When `regex` is matched, `previousEscape` can only capture characters adjacent to `decimalEscape`
if (previousEscape === "\\0") {
/*
* Now we have a NULL escape "\0" immediately followed by a decimal escape, e.g.: "\0\8".
* Fixing this to "\08" would turn "\0" into a legacy octal escape. To avoid producing
* an octal escape while fixing a decimal escape, we provide different suggestions.
*/
suggest.push(
createSuggestion( // "\0\8" -> "\u00008"
"refactor",
[decimalEscapeRangeStart - previousEscape.length, decimalEscapeRangeEnd],
`${getUnicodeEscape("\0")}${decimalEscape[1]}`
),
createSuggestion( // "\8" -> "\u0038"
"refactor",
decimalEscapeRange,
getUnicodeEscape(decimalEscape[1])
)
);
} else {
suggest.push(
createSuggestion( // "\8" -> "8"
"refactor",
decimalEscapeRange,
decimalEscape[1]
)
);
}
suggest.push(
createSuggestion( // "\8" -> "\\8"
"escapeBackslash",
decimalEscapeRange,
`\\${decimalEscape}`
)
);
context.report({
node,
loc: {
start: sourceCode.getLocFromIndex(decimalEscapeRangeStart),
end: sourceCode.getLocFromIndex(decimalEscapeRangeEnd)
},
messageId: "decimalEscape",
data: {
decimalEscape
},
suggest
});
}
}
};
}
};