+++ /dev/null
-/**
- * @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;
-}
-
-/**
- * Determines whether a given node is a octal escape sequence
- * @param {ASTNode} node A node to check
- * @returns {boolean} `true` if the node is an octal escape sequence
- */
-function isOctalEscapeSequence(node) {
-
- // No need to check TemplateLiterals – would throw error with octal escape
- const isStringLiteral = node.type === "Literal" && typeof node.value === "string";
-
- if (!isStringLiteral) {
- return false;
- }
-
- return astUtils.hasOctalEscapeSequence(node.raw);
-}
-
-/**
- * Checks whether or not a node contains a octal escape sequence
- * @param {ASTNode} node A node to check
- * @returns {boolean} `true` if the node contains an octal escape sequence
- */
-function hasOctalEscapeSequence(node) {
- if (isConcatenation(node)) {
- return hasOctalEscapeSequence(node.left) || hasOctalEscapeSequence(node.right);
- }
-
- return isOctalEscapeSequence(node);
-}
-
-/**
- * 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
-//------------------------------------------------------------------------------
-
-module.exports = {
- meta: {
- type: "suggestion",
-
- docs: {
- description: "require template literals instead of string concatenation",
- category: "ECMAScript 6",
- recommended: false,
- url: "https://eslint.org/docs/rules/prefer-template"
- },
-
- schema: [],
- fixable: "code"
- },
-
- 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) && hasNonStringLiteral(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 (hasOctalEscapeSequence(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,
- message: "Unexpected string concatenation.",
- fix: fixer => fixNonStringBinaryExpression(fixer, node)
- });
- }
- }
-
- return {
- Program() {
- done = Object.create(null);
- },
-
- Literal: checkForStringConcat,
- TemplateLiteral: checkForStringConcat
- };
- }
-};
projects / dotfiles / .git / blobdiff