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slider/node_modules/eslint/lib/rules/prefer-exponentiation-operator.js

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+/**
+ * @fileoverview Rule to disallow Math.pow in favor of the ** operator
+ * @author Milos Djermanovic
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const astUtils = require("./utils/ast-utils");
+const { CALL, ReferenceTracker } = require("@eslint-community/eslint-utils");
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+const PRECEDENCE_OF_EXPONENTIATION_EXPR = astUtils.getPrecedence({
+	type: "BinaryExpression",
+	operator: "**",
+});
+
+/**
+ * Determines whether the given node needs parens if used as the base in an exponentiation binary expression.
+ * @param {ASTNode} base The node to check.
+ * @returns {boolean} `true` if the node needs to be parenthesised.
+ */
+function doesBaseNeedParens(base) {
+	return (
+		// '**' is right-associative, parens are needed when Math.pow(a ** b, c) is converted to (a ** b) ** c
+		astUtils.getPrecedence(base) <= PRECEDENCE_OF_EXPONENTIATION_EXPR ||
+		// An unary operator cannot be used immediately before an exponentiation expression
+		base.type === "AwaitExpression" ||
+		base.type === "UnaryExpression"
+	);
+}
+
+/**
+ * Determines whether the given node needs parens if used as the exponent in an exponentiation binary expression.
+ * @param {ASTNode} exponent The node to check.
+ * @returns {boolean} `true` if the node needs to be parenthesised.
+ */
+function doesExponentNeedParens(exponent) {
+	// '**' is right-associative, there is no need for parens when Math.pow(a, b ** c) is converted to a ** b ** c
+	return astUtils.getPrecedence(exponent) < PRECEDENCE_OF_EXPONENTIATION_EXPR;
+}
+
+/**
+ * Determines whether an exponentiation binary expression at the place of the given node would need parens.
+ * @param {ASTNode} node A node that would be replaced by an exponentiation binary expression.
+ * @param {SourceCode} sourceCode A SourceCode object.
+ * @returns {boolean} `true` if the expression needs to be parenthesised.
+ */
+function doesExponentiationExpressionNeedParens(node, sourceCode) {
+	const parent =
+		node.parent.type === "ChainExpression"
+			? node.parent.parent
+			: node.parent;
+
+	const parentPrecedence = astUtils.getPrecedence(parent);
+	const needsParens =
+		parent.type === "ClassDeclaration" ||
+		(parent.type.endsWith("Expression") &&
+			(parentPrecedence === -1 ||
+				parentPrecedence >= PRECEDENCE_OF_EXPONENTIATION_EXPR) &&
+			!(
+				parent.type === "BinaryExpression" &&
+				parent.operator === "**" &&
+				parent.right === node
+			) &&
+			!(
+				(parent.type === "CallExpression" ||
+					parent.type === "NewExpression") &&
+				parent.arguments.includes(node)
+			) &&
+			!(
+				parent.type === "MemberExpression" &&
+				parent.computed &&
+				parent.property === node
+			) &&
+			!(parent.type === "ArrayExpression"));
+
+	return needsParens && !astUtils.isParenthesised(sourceCode, node);
+}
+
+/**
+ * Optionally parenthesizes given text.
+ * @param {string} text The text to parenthesize.
+ * @param {boolean} shouldParenthesize If `true`, the text will be parenthesised.
+ * @returns {string} parenthesised or unchanged text.
+ */
+function parenthesizeIfShould(text, shouldParenthesize) {
+	return shouldParenthesize ? `(${text})` : text;
+}
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+/** @type {import('../types').Rule.RuleModule} */
+module.exports = {
+	meta: {
+		type: "suggestion",
+
+		docs: {
+			description:
+				"Disallow the use of `Math.pow` in favor of the `**` operator",
+			recommended: false,
+			frozen: true,
+			url: "https://eslint.org/docs/latest/rules/prefer-exponentiation-operator",
+		},
+
+		schema: [],
+		fixable: "code",
+
+		messages: {
+			useExponentiation: "Use the '**' operator instead of 'Math.pow'.",
+		},
+	},
+
+	create(context) {
+		const sourceCode = context.sourceCode;
+
+		/**
+		 * Reports the given node.
+		 * @param {ASTNode} node 'Math.pow()' node to report.
+		 * @returns {void}
+		 */
+		function report(node) {
+			context.report({
+				node,
+				messageId: "useExponentiation",
+				fix(fixer) {
+					if (
+						node.arguments.length !== 2 ||
+						node.arguments.some(
+							arg => arg.type === "SpreadElement",
+						) ||
+						sourceCode.getCommentsInside(node).length > 0
+					) {
+						return null;
+					}
+
+					const base = node.arguments[0],
+						exponent = node.arguments[1],
+						baseText = sourceCode.getText(base),
+						exponentText = sourceCode.getText(exponent),
+						shouldParenthesizeBase = doesBaseNeedParens(base),
+						shouldParenthesizeExponent =
+							doesExponentNeedParens(exponent),
+						shouldParenthesizeAll =
+							doesExponentiationExpressionNeedParens(
+								node,
+								sourceCode,
+							);
+
+					let prefix = "",
+						suffix = "";
+
+					if (!shouldParenthesizeAll) {
+						if (!shouldParenthesizeBase) {
+							const firstReplacementToken =
+									sourceCode.getFirstToken(base),
+								tokenBefore = sourceCode.getTokenBefore(node);
+
+							if (
+								tokenBefore &&
+								tokenBefore.range[1] === node.range[0] &&
+								!astUtils.canTokensBeAdjacent(
+									tokenBefore,
+									firstReplacementToken,
+								)
+							) {
+								prefix = " "; // a+Math.pow(++b, c) -> a+ ++b**c
+							}
+						}
+						if (!shouldParenthesizeExponent) {
+							const lastReplacementToken =
+									sourceCode.getLastToken(exponent),
+								tokenAfter = sourceCode.getTokenAfter(node);
+
+							if (
+								tokenAfter &&
+								node.range[1] === tokenAfter.range[0] &&
+								!astUtils.canTokensBeAdjacent(
+									lastReplacementToken,
+									tokenAfter,
+								)
+							) {
+								suffix = " "; // Math.pow(a, b)in c -> a**b in c
+							}
+						}
+					}
+
+					const baseReplacement = parenthesizeIfShould(
+							baseText,
+							shouldParenthesizeBase,
+						),
+						exponentReplacement = parenthesizeIfShould(
+							exponentText,
+							shouldParenthesizeExponent,
+						),
+						replacement = parenthesizeIfShould(
+							`${baseReplacement}**${exponentReplacement}`,
+							shouldParenthesizeAll,
+						);
+
+					return fixer.replaceText(
+						node,
+						`${prefix}${replacement}${suffix}`,
+					);
+				},
+			});
+		}
+
+		return {
+			Program(node) {
+				const scope = sourceCode.getScope(node);
+				const tracker = new ReferenceTracker(scope);
+				const trackMap = {
+					Math: {
+						pow: { [CALL]: true },
+					},
+				};
+
+				for (const { node: refNode } of tracker.iterateGlobalReferences(
+					trackMap,
+				)) {
+					report(refNode);
+				}
+			},
+		};
+	},
+};