209 lines
7.4 KiB
JavaScript
209 lines
7.4 KiB
JavaScript
/**
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* @fileoverview Rule to flag trailing underscores in variable declarations.
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* @author Matt DuVall <http://www.mattduvall.com>
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*/
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"use strict";
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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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: "disallow dangling underscores in identifiers",
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category: "Stylistic Issues",
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recommended: false,
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url: "https://eslint.org/docs/rules/no-underscore-dangle"
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},
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schema: [
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{
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type: "object",
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properties: {
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allow: {
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type: "array",
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items: {
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type: "string"
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}
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},
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allowAfterThis: {
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type: "boolean",
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default: false
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},
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allowAfterSuper: {
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type: "boolean",
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default: false
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},
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enforceInMethodNames: {
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type: "boolean",
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default: false
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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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},
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create(context) {
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const options = context.options[0] || {};
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const ALLOWED_VARIABLES = options.allow ? options.allow : [];
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const allowAfterThis = typeof options.allowAfterThis !== "undefined" ? options.allowAfterThis : false;
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const allowAfterSuper = typeof options.allowAfterSuper !== "undefined" ? options.allowAfterSuper : false;
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const enforceInMethodNames = typeof options.enforceInMethodNames !== "undefined" ? options.enforceInMethodNames : false;
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//-------------------------------------------------------------------------
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// Helpers
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//-------------------------------------------------------------------------
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/**
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* Check if identifier is present inside the allowed option
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* @param {string} identifier name of the node
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* @returns {boolean} true if its is present
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* @private
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*/
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function isAllowed(identifier) {
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return ALLOWED_VARIABLES.some(ident => ident === identifier);
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}
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/**
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* Check if identifier has a underscore at the end
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* @param {ASTNode} identifier node to evaluate
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* @returns {boolean} true if its is present
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* @private
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*/
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function hasTrailingUnderscore(identifier) {
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const len = identifier.length;
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return identifier !== "_" && (identifier[0] === "_" || identifier[len - 1] === "_");
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}
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/**
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* Check if identifier is a special case member expression
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* @param {ASTNode} identifier node to evaluate
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* @returns {boolean} true if its is a special case
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* @private
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*/
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function isSpecialCaseIdentifierForMemberExpression(identifier) {
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return identifier === "__proto__";
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}
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/**
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* Check if identifier is a special case variable expression
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* @param {ASTNode} identifier node to evaluate
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* @returns {boolean} true if its is a special case
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* @private
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*/
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function isSpecialCaseIdentifierInVariableExpression(identifier) {
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// Checks for the underscore library usage here
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return identifier === "_";
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}
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/**
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* Check if function has a underscore at the end
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* @param {ASTNode} node node to evaluate
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* @returns {void}
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* @private
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*/
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function checkForTrailingUnderscoreInFunctionDeclaration(node) {
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if (node.id) {
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const identifier = node.id.name;
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if (typeof identifier !== "undefined" && hasTrailingUnderscore(identifier) && !isAllowed(identifier)) {
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context.report({
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node,
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message: "Unexpected dangling '_' in '{{identifier}}'.",
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data: {
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identifier
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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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* Check if variable expression has a underscore at the end
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* @param {ASTNode} node node to evaluate
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* @returns {void}
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* @private
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*/
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function checkForTrailingUnderscoreInVariableExpression(node) {
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const identifier = node.id.name;
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if (typeof identifier !== "undefined" && hasTrailingUnderscore(identifier) &&
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!isSpecialCaseIdentifierInVariableExpression(identifier) && !isAllowed(identifier)) {
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context.report({
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node,
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message: "Unexpected dangling '_' in '{{identifier}}'.",
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data: {
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identifier
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}
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});
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}
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}
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/**
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* Check if member expression has a underscore at the end
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* @param {ASTNode} node node to evaluate
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* @returns {void}
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* @private
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*/
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function checkForTrailingUnderscoreInMemberExpression(node) {
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const identifier = node.property.name,
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isMemberOfThis = node.object.type === "ThisExpression",
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isMemberOfSuper = node.object.type === "Super";
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if (typeof identifier !== "undefined" && hasTrailingUnderscore(identifier) &&
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!(isMemberOfThis && allowAfterThis) &&
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!(isMemberOfSuper && allowAfterSuper) &&
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!isSpecialCaseIdentifierForMemberExpression(identifier) && !isAllowed(identifier)) {
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context.report({
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node,
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message: "Unexpected dangling '_' in '{{identifier}}'.",
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data: {
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identifier
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}
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});
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}
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}
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/**
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* Check if method declaration or method property has a underscore at the end
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* @param {ASTNode} node node to evaluate
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* @returns {void}
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* @private
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*/
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function checkForTrailingUnderscoreInMethod(node) {
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const identifier = node.key.name;
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const isMethod = node.type === "MethodDefinition" || node.type === "Property" && node.method;
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if (typeof identifier !== "undefined" && enforceInMethodNames && isMethod && hasTrailingUnderscore(identifier)) {
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context.report({
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node,
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message: "Unexpected dangling '_' in '{{identifier}}'.",
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data: {
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identifier
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}
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});
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}
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}
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//--------------------------------------------------------------------------
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// Public API
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//--------------------------------------------------------------------------
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return {
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FunctionDeclaration: checkForTrailingUnderscoreInFunctionDeclaration,
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VariableDeclarator: checkForTrailingUnderscoreInVariableExpression,
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MemberExpression: checkForTrailingUnderscoreInMemberExpression,
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MethodDefinition: checkForTrailingUnderscoreInMethod,
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Property: checkForTrailingUnderscoreInMethod
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};
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}
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};
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