Constnium/node_modules/eslint/lib/rules/prefer-template.js
2022-06-23 02:27:43 +02:00

275 lines
11 KiB
JavaScript
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

/**
* @fileoverview A rule to suggest using template literals instead of string concatenation.
* @author Toru Nagashima
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const astUtils = require("./utils/ast-utils");
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
/**
* Checks whether or not a given node is a concatenation.
* @param {ASTNode} node A node to check.
* @returns {boolean} `true` if the node is a concatenation.
*/
function isConcatenation(node) {
return node.type === "BinaryExpression" && node.operator === "+";
}
/**
* Gets the top binary expression node for concatenation in parents of a given node.
* @param {ASTNode} node A node to get.
* @returns {ASTNode} the top binary expression node in parents of a given node.
*/
function getTopConcatBinaryExpression(node) {
let currentNode = node;
while (isConcatenation(currentNode.parent)) {
currentNode = currentNode.parent;
}
return currentNode;
}
/**
* Checks whether or not a node contains a string literal with an octal or non-octal decimal escape sequence
* @param {ASTNode} node A node to check
* @returns {boolean} `true` if at least one string literal within the node contains
* an octal or non-octal decimal escape sequence
*/
function hasOctalOrNonOctalDecimalEscapeSequence(node) {
if (isConcatenation(node)) {
return (
hasOctalOrNonOctalDecimalEscapeSequence(node.left) ||
hasOctalOrNonOctalDecimalEscapeSequence(node.right)
);
}
// No need to check TemplateLiterals would throw parsing error
if (node.type === "Literal" && typeof node.value === "string") {
return astUtils.hasOctalOrNonOctalDecimalEscapeSequence(node.raw);
}
return false;
}
/**
* Checks whether or not a given binary expression has string literals.
* @param {ASTNode} node A node to check.
* @returns {boolean} `true` if the node has string literals.
*/
function hasStringLiteral(node) {
if (isConcatenation(node)) {
// `left` is deeper than `right` normally.
return hasStringLiteral(node.right) || hasStringLiteral(node.left);
}
return astUtils.isStringLiteral(node);
}
/**
* Checks whether or not a given binary expression has non string literals.
* @param {ASTNode} node A node to check.
* @returns {boolean} `true` if the node has non string literals.
*/
function hasNonStringLiteral(node) {
if (isConcatenation(node)) {
// `left` is deeper than `right` normally.
return hasNonStringLiteral(node.right) || hasNonStringLiteral(node.left);
}
return !astUtils.isStringLiteral(node);
}
/**
* Determines whether a given node will start with a template curly expression (`${}`) when being converted to a template literal.
* @param {ASTNode} node The node that will be fixed to a template literal
* @returns {boolean} `true` if the node will start with a template curly.
*/
function startsWithTemplateCurly(node) {
if (node.type === "BinaryExpression") {
return startsWithTemplateCurly(node.left);
}
if (node.type === "TemplateLiteral") {
return node.expressions.length && node.quasis.length && node.quasis[0].range[0] === node.quasis[0].range[1];
}
return node.type !== "Literal" || typeof node.value !== "string";
}
/**
* Determines whether a given node end with a template curly expression (`${}`) when being converted to a template literal.
* @param {ASTNode} node The node that will be fixed to a template literal
* @returns {boolean} `true` if the node will end with a template curly.
*/
function endsWithTemplateCurly(node) {
if (node.type === "BinaryExpression") {
return startsWithTemplateCurly(node.right);
}
if (node.type === "TemplateLiteral") {
return node.expressions.length && node.quasis.length && node.quasis[node.quasis.length - 1].range[0] === node.quasis[node.quasis.length - 1].range[1];
}
return node.type !== "Literal" || typeof node.value !== "string";
}
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
/** @type {import('../shared/types').Rule} */
module.exports = {
meta: {
type: "suggestion",
docs: {
description: "require template literals instead of string concatenation",
recommended: false,
url: "https://eslint.org/docs/rules/prefer-template"
},
schema: [],
fixable: "code",
messages: {
unexpectedStringConcatenation: "Unexpected string concatenation."
}
},
create(context) {
const sourceCode = context.getSourceCode();
let done = Object.create(null);
/**
* Gets the non-token text between two nodes, ignoring any other tokens that appear between the two tokens.
* @param {ASTNode} node1 The first node
* @param {ASTNode} node2 The second node
* @returns {string} The text between the nodes, excluding other tokens
*/
function getTextBetween(node1, node2) {
const allTokens = [node1].concat(sourceCode.getTokensBetween(node1, node2)).concat(node2);
const sourceText = sourceCode.getText();
return allTokens.slice(0, -1).reduce((accumulator, token, index) => accumulator + sourceText.slice(token.range[1], allTokens[index + 1].range[0]), "");
}
/**
* Returns a template literal form of the given node.
* @param {ASTNode} currentNode A node that should be converted to a template literal
* @param {string} textBeforeNode Text that should appear before the node
* @param {string} textAfterNode Text that should appear after the node
* @returns {string} A string form of this node, represented as a template literal
*/
function getTemplateLiteral(currentNode, textBeforeNode, textAfterNode) {
if (currentNode.type === "Literal" && typeof currentNode.value === "string") {
/*
* If the current node is a string literal, escape any instances of ${ or ` to prevent them from being interpreted
* as a template placeholder. However, if the code already contains a backslash before the ${ or `
* for some reason, don't add another backslash, because that would change the meaning of the code (it would cause
* an actual backslash character to appear before the dollar sign).
*/
return `\`${currentNode.raw.slice(1, -1).replace(/\\*(\$\{|`)/gu, matched => {
if (matched.lastIndexOf("\\") % 2) {
return `\\${matched}`;
}
return matched;
// Unescape any quotes that appear in the original Literal that no longer need to be escaped.
}).replace(new RegExp(`\\\\${currentNode.raw[0]}`, "gu"), currentNode.raw[0])}\``;
}
if (currentNode.type === "TemplateLiteral") {
return sourceCode.getText(currentNode);
}
if (isConcatenation(currentNode) && hasStringLiteral(currentNode)) {
const plusSign = sourceCode.getFirstTokenBetween(currentNode.left, currentNode.right, token => token.value === "+");
const textBeforePlus = getTextBetween(currentNode.left, plusSign);
const textAfterPlus = getTextBetween(plusSign, currentNode.right);
const leftEndsWithCurly = endsWithTemplateCurly(currentNode.left);
const rightStartsWithCurly = startsWithTemplateCurly(currentNode.right);
if (leftEndsWithCurly) {
// If the left side of the expression ends with a template curly, add the extra text to the end of the curly bracket.
// `foo${bar}` /* comment */ + 'baz' --> `foo${bar /* comment */ }${baz}`
return getTemplateLiteral(currentNode.left, textBeforeNode, textBeforePlus + textAfterPlus).slice(0, -1) +
getTemplateLiteral(currentNode.right, null, textAfterNode).slice(1);
}
if (rightStartsWithCurly) {
// Otherwise, if the right side of the expression starts with a template curly, add the text there.
// 'foo' /* comment */ + `${bar}baz` --> `foo${ /* comment */ bar}baz`
return getTemplateLiteral(currentNode.left, textBeforeNode, null).slice(0, -1) +
getTemplateLiteral(currentNode.right, textBeforePlus + textAfterPlus, textAfterNode).slice(1);
}
/*
* Otherwise, these nodes should not be combined into a template curly, since there is nowhere to put
* the text between them.
*/
return `${getTemplateLiteral(currentNode.left, textBeforeNode, null)}${textBeforePlus}+${textAfterPlus}${getTemplateLiteral(currentNode.right, textAfterNode, null)}`;
}
return `\`\${${textBeforeNode || ""}${sourceCode.getText(currentNode)}${textAfterNode || ""}}\``;
}
/**
* Returns a fixer object that converts a non-string binary expression to a template literal
* @param {SourceCodeFixer} fixer The fixer object
* @param {ASTNode} node A node that should be converted to a template literal
* @returns {Object} A fix for this binary expression
*/
function fixNonStringBinaryExpression(fixer, node) {
const topBinaryExpr = getTopConcatBinaryExpression(node.parent);
if (hasOctalOrNonOctalDecimalEscapeSequence(topBinaryExpr)) {
return null;
}
return fixer.replaceText(topBinaryExpr, getTemplateLiteral(topBinaryExpr, null, null));
}
/**
* Reports if a given node is string concatenation with non string literals.
* @param {ASTNode} node A node to check.
* @returns {void}
*/
function checkForStringConcat(node) {
if (!astUtils.isStringLiteral(node) || !isConcatenation(node.parent)) {
return;
}
const topBinaryExpr = getTopConcatBinaryExpression(node.parent);
// Checks whether or not this node had been checked already.
if (done[topBinaryExpr.range[0]]) {
return;
}
done[topBinaryExpr.range[0]] = true;
if (hasNonStringLiteral(topBinaryExpr)) {
context.report({
node: topBinaryExpr,
messageId: "unexpectedStringConcatenation",
fix: fixer => fixNonStringBinaryExpression(fixer, node)
});
}
}
return {
Program() {
done = Object.create(null);
},
Literal: checkForStringConcat,
TemplateLiteral: checkForStringConcat
};
}
};