+++ /dev/null
-/**
- * @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-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 === "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;
-
- const needsParens = (
- parent.type === "ClassDeclaration" ||
- (
- parent.type.endsWith("Expression") &&
- astUtils.getPrecedence(parent) >= 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
-//------------------------------------------------------------------------------
-
-module.exports = {
- meta: {
- type: "suggestion",
-
- docs: {
- description: "disallow the use of `Math.pow` in favor of the `**` operator",
- category: "Stylistic Issues",
- recommended: false,
- url: "https://eslint.org/docs/rules/prefer-exponentiation-operator"
- },
-
- schema: [],
- fixable: "code",
-
- messages: {
- useExponentiation: "Use the '**' operator instead of 'Math.pow'."
- }
- },
-
- create(context) {
- const sourceCode = context.getSourceCode();
-
- /**
- * 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() {
- const scope = context.getScope();
- const tracker = new ReferenceTracker(scope);
- const trackMap = {
- Math: {
- pow: { [CALL]: true }
- }
- };
-
- for (const { node } of tracker.iterateGlobalReferences(trackMap)) {
- report(node);
- }
- }
- };
- }
-};
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