--- /dev/null
+/**
+ * @fileoverview A rule to choose between single and double quote marks
+ * @author Matt DuVall <http://www.mattduvall.com/>, Brandon Payton
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const astUtils = require("./utils/ast-utils");
+
+//------------------------------------------------------------------------------
+// Constants
+//------------------------------------------------------------------------------
+
+const QUOTE_SETTINGS = {
+ double: {
+ quote: "\"",
+ alternateQuote: "'",
+ description: "doublequote"
+ },
+ single: {
+ quote: "'",
+ alternateQuote: "\"",
+ description: "singlequote"
+ },
+ backtick: {
+ quote: "`",
+ alternateQuote: "\"",
+ description: "backtick"
+ }
+};
+
+// An unescaped newline is a newline preceded by an even number of backslashes.
+const UNESCAPED_LINEBREAK_PATTERN = new RegExp(String.raw`(^|[^\\])(\\\\)*[${Array.from(astUtils.LINEBREAKS).join("")}]`, "u");
+
+/**
+ * Switches quoting of javascript string between ' " and `
+ * escaping and unescaping as necessary.
+ * Only escaping of the minimal set of characters is changed.
+ * Note: escaping of newlines when switching from backtick to other quotes is not handled.
+ * @param {string} str A string to convert.
+ * @returns {string} The string with changed quotes.
+ * @private
+ */
+QUOTE_SETTINGS.double.convert =
+QUOTE_SETTINGS.single.convert =
+QUOTE_SETTINGS.backtick.convert = function(str) {
+ const newQuote = this.quote;
+ const oldQuote = str[0];
+
+ if (newQuote === oldQuote) {
+ return str;
+ }
+ return newQuote + str.slice(1, -1).replace(/\\(\$\{|\r\n?|\n|.)|["'`]|\$\{|(\r\n?|\n)/gu, (match, escaped, newline) => {
+ if (escaped === oldQuote || oldQuote === "`" && escaped === "${") {
+ return escaped; // unescape
+ }
+ if (match === newQuote || newQuote === "`" && match === "${") {
+ return `\\${match}`; // escape
+ }
+ if (newline && oldQuote === "`") {
+ return "\\n"; // escape newlines
+ }
+ return match;
+ }) + newQuote;
+};
+
+const AVOID_ESCAPE = "avoid-escape";
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+ meta: {
+ type: "layout",
+
+ docs: {
+ description: "enforce the consistent use of either backticks, double, or single quotes",
+ category: "Stylistic Issues",
+ recommended: false,
+ url: "https://eslint.org/docs/rules/quotes"
+ },
+
+ fixable: "code",
+
+ schema: [
+ {
+ enum: ["single", "double", "backtick"]
+ },
+ {
+ anyOf: [
+ {
+ enum: ["avoid-escape"]
+ },
+ {
+ type: "object",
+ properties: {
+ avoidEscape: {
+ type: "boolean"
+ },
+ allowTemplateLiterals: {
+ type: "boolean"
+ }
+ },
+ additionalProperties: false
+ }
+ ]
+ }
+ ],
+
+ messages: {
+ wrongQuotes: "Strings must use {{description}}."
+ }
+ },
+
+ create(context) {
+
+ const quoteOption = context.options[0],
+ settings = QUOTE_SETTINGS[quoteOption || "double"],
+ options = context.options[1],
+ allowTemplateLiterals = options && options.allowTemplateLiterals === true,
+ sourceCode = context.getSourceCode();
+ let avoidEscape = options && options.avoidEscape === true;
+
+ // deprecated
+ if (options === AVOID_ESCAPE) {
+ avoidEscape = true;
+ }
+
+ /**
+ * Determines if a given node is part of JSX syntax.
+ *
+ * This function returns `true` in the following cases:
+ *
+ * - `<div className="foo"></div>` ... If the literal is an attribute value, the parent of the literal is `JSXAttribute`.
+ * - `<div>foo</div>` ... If the literal is a text content, the parent of the literal is `JSXElement`.
+ * - `<>foo</>` ... If the literal is a text content, the parent of the literal is `JSXFragment`.
+ *
+ * In particular, this function returns `false` in the following cases:
+ *
+ * - `<div className={"foo"}></div>`
+ * - `<div>{"foo"}</div>`
+ *
+ * In both cases, inside of the braces is handled as normal JavaScript.
+ * The braces are `JSXExpressionContainer` nodes.
+ * @param {ASTNode} node The Literal node to check.
+ * @returns {boolean} True if the node is a part of JSX, false if not.
+ * @private
+ */
+ function isJSXLiteral(node) {
+ return node.parent.type === "JSXAttribute" || node.parent.type === "JSXElement" || node.parent.type === "JSXFragment";
+ }
+
+ /**
+ * Checks whether or not a given node is a directive.
+ * The directive is a `ExpressionStatement` which has only a string literal.
+ * @param {ASTNode} node A node to check.
+ * @returns {boolean} Whether or not the node is a directive.
+ * @private
+ */
+ function isDirective(node) {
+ return (
+ node.type === "ExpressionStatement" &&
+ node.expression.type === "Literal" &&
+ typeof node.expression.value === "string"
+ );
+ }
+
+ /**
+ * Checks whether or not a given node is a part of directive prologues.
+ * See also: http://www.ecma-international.org/ecma-262/6.0/#sec-directive-prologues-and-the-use-strict-directive
+ * @param {ASTNode} node A node to check.
+ * @returns {boolean} Whether or not the node is a part of directive prologues.
+ * @private
+ */
+ function isPartOfDirectivePrologue(node) {
+ const block = node.parent.parent;
+
+ if (block.type !== "Program" && (block.type !== "BlockStatement" || !astUtils.isFunction(block.parent))) {
+ return false;
+ }
+
+ // Check the node is at a prologue.
+ for (let i = 0; i < block.body.length; ++i) {
+ const statement = block.body[i];
+
+ if (statement === node.parent) {
+ return true;
+ }
+ if (!isDirective(statement)) {
+ break;
+ }
+ }
+
+ return false;
+ }
+
+ /**
+ * Checks whether or not a given node is allowed as non backtick.
+ * @param {ASTNode} node A node to check.
+ * @returns {boolean} Whether or not the node is allowed as non backtick.
+ * @private
+ */
+ function isAllowedAsNonBacktick(node) {
+ const parent = node.parent;
+
+ switch (parent.type) {
+
+ // Directive Prologues.
+ case "ExpressionStatement":
+ return isPartOfDirectivePrologue(node);
+
+ // LiteralPropertyName.
+ case "Property":
+ case "MethodDefinition":
+ return parent.key === node && !parent.computed;
+
+ // ModuleSpecifier.
+ case "ImportDeclaration":
+ case "ExportNamedDeclaration":
+ case "ExportAllDeclaration":
+ return parent.source === node;
+
+ // Others don't allow.
+ default:
+ return false;
+ }
+ }
+
+ /**
+ * Checks whether or not a given TemplateLiteral node is actually using any of the special features provided by template literal strings.
+ * @param {ASTNode} node A TemplateLiteral node to check.
+ * @returns {boolean} Whether or not the TemplateLiteral node is using any of the special features provided by template literal strings.
+ * @private
+ */
+ function isUsingFeatureOfTemplateLiteral(node) {
+ const hasTag = node.parent.type === "TaggedTemplateExpression" && node === node.parent.quasi;
+
+ if (hasTag) {
+ return true;
+ }
+
+ const hasStringInterpolation = node.expressions.length > 0;
+
+ if (hasStringInterpolation) {
+ return true;
+ }
+
+ const isMultilineString = node.quasis.length >= 1 && UNESCAPED_LINEBREAK_PATTERN.test(node.quasis[0].value.raw);
+
+ if (isMultilineString) {
+ return true;
+ }
+
+ return false;
+ }
+
+ return {
+
+ Literal(node) {
+ const val = node.value,
+ rawVal = node.raw;
+
+ if (settings && typeof val === "string") {
+ let isValid = (quoteOption === "backtick" && isAllowedAsNonBacktick(node)) ||
+ isJSXLiteral(node) ||
+ astUtils.isSurroundedBy(rawVal, settings.quote);
+
+ if (!isValid && avoidEscape) {
+ isValid = astUtils.isSurroundedBy(rawVal, settings.alternateQuote) && rawVal.indexOf(settings.quote) >= 0;
+ }
+
+ if (!isValid) {
+ context.report({
+ node,
+ messageId: "wrongQuotes",
+ data: {
+ description: settings.description
+ },
+ fix(fixer) {
+ if (quoteOption === "backtick" && astUtils.hasOctalOrNonOctalDecimalEscapeSequence(rawVal)) {
+
+ /*
+ * An octal or non-octal decimal escape sequence in a template literal would
+ * produce syntax error, even in non-strict mode.
+ */
+ return null;
+ }
+
+ return fixer.replaceText(node, settings.convert(node.raw));
+ }
+ });
+ }
+ }
+ },
+
+ TemplateLiteral(node) {
+
+ // Don't throw an error if backticks are expected or a template literal feature is in use.
+ if (
+ allowTemplateLiterals ||
+ quoteOption === "backtick" ||
+ isUsingFeatureOfTemplateLiteral(node)
+ ) {
+ return;
+ }
+
+ context.report({
+ node,
+ messageId: "wrongQuotes",
+ data: {
+ description: settings.description
+ },
+ fix(fixer) {
+ if (isPartOfDirectivePrologue(node)) {
+
+ /*
+ * TemplateLiterals in a directive prologue aren't actually directives, but if they're
+ * in the directive prologue, then fixing them might turn them into directives and change
+ * the behavior of the code.
+ */
+ return null;
+ }
+ return fixer.replaceText(node, settings.convert(sourceCode.getText(node)));
+ }
+ });
+ }
+ };
+
+ }
+};
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