140 lines
4.4 KiB
JavaScript
140 lines
4.4 KiB
JavaScript
/**
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* @fileoverview A rule to control the style of variable initializations.
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* @author Colin Ihrig
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*/
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"use strict";
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//------------------------------------------------------------------------------
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// Helpers
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//------------------------------------------------------------------------------
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/**
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* Checks whether or not a given node is a for loop.
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* @param {ASTNode} block A node to check.
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* @returns {boolean} `true` when the node is a for loop.
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*/
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function isForLoop(block) {
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return block.type === "ForInStatement" ||
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block.type === "ForOfStatement" ||
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block.type === "ForStatement";
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}
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/**
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* Checks whether or not a given declarator node has its initializer.
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* @param {ASTNode} node A declarator node to check.
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* @returns {boolean} `true` when the node has its initializer.
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*/
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function isInitialized(node) {
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const declaration = node.parent;
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const block = declaration.parent;
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if (isForLoop(block)) {
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if (block.type === "ForStatement") {
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return block.init === declaration;
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}
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return block.left === declaration;
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}
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return Boolean(node.init);
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}
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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/** @type {import('../shared/types').Rule} */
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module.exports = {
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meta: {
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type: "suggestion",
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docs: {
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description: "Require or disallow initialization in variable declarations",
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recommended: false,
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url: "https://eslint.org/docs/latest/rules/init-declarations"
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},
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schema: {
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anyOf: [
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{
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type: "array",
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items: [
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{
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enum: ["always"]
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}
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],
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minItems: 0,
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maxItems: 1
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},
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{
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type: "array",
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items: [
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{
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enum: ["never"]
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},
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{
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type: "object",
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properties: {
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ignoreForLoopInit: {
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type: "boolean"
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}
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},
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additionalProperties: false
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}
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],
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minItems: 0,
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maxItems: 2
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}
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]
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},
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messages: {
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initialized: "Variable '{{idName}}' should be initialized on declaration.",
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notInitialized: "Variable '{{idName}}' should not be initialized on declaration."
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}
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},
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create(context) {
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const MODE_ALWAYS = "always",
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MODE_NEVER = "never";
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const mode = context.options[0] || MODE_ALWAYS;
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const params = context.options[1] || {};
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//--------------------------------------------------------------------------
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// Public API
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//--------------------------------------------------------------------------
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return {
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"VariableDeclaration:exit"(node) {
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const kind = node.kind,
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declarations = node.declarations;
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for (let i = 0; i < declarations.length; ++i) {
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const declaration = declarations[i],
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id = declaration.id,
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initialized = isInitialized(declaration),
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isIgnoredForLoop = params.ignoreForLoopInit && isForLoop(node.parent);
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let messageId = "";
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if (mode === MODE_ALWAYS && !initialized) {
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messageId = "initialized";
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} else if (mode === MODE_NEVER && kind !== "const" && initialized && !isIgnoredForLoop) {
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messageId = "notInitialized";
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}
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if (id.type === "Identifier" && messageId) {
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context.report({
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node: declaration,
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messageId,
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data: {
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idName: id.name
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}
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});
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}
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}
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}
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};
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}
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};
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