424 lines
15 KiB
JavaScript
424 lines
15 KiB
JavaScript
/**
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* @fileoverview A rule to verify `super()` callings in constructor.
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* @author Toru Nagashima
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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 a given code path segment is reachable or not.
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* @param {CodePathSegment} segment A code path segment to check.
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* @returns {boolean} `true` if the segment is reachable.
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*/
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function isReachable(segment) {
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return segment.reachable;
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}
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/**
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* Checks whether or not a given node is a constructor.
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* @param {ASTNode} node A node to check. This node type is one of
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* `Program`, `FunctionDeclaration`, `FunctionExpression`, and
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* `ArrowFunctionExpression`.
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* @returns {boolean} `true` if the node is a constructor.
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*/
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function isConstructorFunction(node) {
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return (
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node.type === "FunctionExpression" &&
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node.parent.type === "MethodDefinition" &&
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node.parent.kind === "constructor"
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);
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}
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/**
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* Checks whether a given node can be a constructor or not.
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* @param {ASTNode} node A node to check.
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* @returns {boolean} `true` if the node can be a constructor.
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*/
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function isPossibleConstructor(node) {
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if (!node) {
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return false;
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}
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switch (node.type) {
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case "ClassExpression":
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case "FunctionExpression":
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case "ThisExpression":
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case "MemberExpression":
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case "CallExpression":
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case "NewExpression":
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case "ChainExpression":
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case "YieldExpression":
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case "TaggedTemplateExpression":
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case "MetaProperty":
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return true;
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case "Identifier":
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return node.name !== "undefined";
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case "AssignmentExpression":
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if (["=", "&&="].includes(node.operator)) {
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return isPossibleConstructor(node.right);
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}
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if (["||=", "??="].includes(node.operator)) {
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return (
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isPossibleConstructor(node.left) ||
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isPossibleConstructor(node.right)
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);
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}
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/**
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* All other assignment operators are mathematical assignment operators (arithmetic or bitwise).
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* An assignment expression with a mathematical operator can either evaluate to a primitive value,
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* or throw, depending on the operands. Thus, it cannot evaluate to a constructor function.
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*/
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return false;
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case "LogicalExpression":
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/*
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* If the && operator short-circuits, the left side was falsy and therefore not a constructor, and if
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* it doesn't short-circuit, it takes the value from the right side, so the right side must always be a
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* possible constructor. A future improvement could verify that the left side could be truthy by
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* excluding falsy literals.
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*/
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if (node.operator === "&&") {
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return isPossibleConstructor(node.right);
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}
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return (
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isPossibleConstructor(node.left) ||
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isPossibleConstructor(node.right)
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);
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case "ConditionalExpression":
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return (
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isPossibleConstructor(node.alternate) ||
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isPossibleConstructor(node.consequent)
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);
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case "SequenceExpression": {
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const lastExpression = node.expressions[node.expressions.length - 1];
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return isPossibleConstructor(lastExpression);
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}
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default:
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return false;
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}
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}
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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: "problem",
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docs: {
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description: "require `super()` calls in constructors",
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category: "ECMAScript 6",
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recommended: true,
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url: "https://eslint.org/docs/rules/constructor-super"
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},
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schema: [],
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messages: {
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missingSome: "Lacked a call of 'super()' in some code paths.",
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missingAll: "Expected to call 'super()'.",
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duplicate: "Unexpected duplicate 'super()'.",
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badSuper: "Unexpected 'super()' because 'super' is not a constructor.",
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unexpected: "Unexpected 'super()'."
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}
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},
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create(context) {
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/*
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* {{hasExtends: boolean, scope: Scope, codePath: CodePath}[]}
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* Information for each constructor.
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* - upper: Information of the upper constructor.
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* - hasExtends: A flag which shows whether own class has a valid `extends`
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* part.
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* - scope: The scope of own class.
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* - codePath: The code path object of the constructor.
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*/
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let funcInfo = null;
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/*
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* {Map<string, {calledInSomePaths: boolean, calledInEveryPaths: boolean}>}
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* Information for each code path segment.
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* - calledInSomePaths: A flag of be called `super()` in some code paths.
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* - calledInEveryPaths: A flag of be called `super()` in all code paths.
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* - validNodes:
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*/
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let segInfoMap = Object.create(null);
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/**
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* Gets the flag which shows `super()` is called in some paths.
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* @param {CodePathSegment} segment A code path segment to get.
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* @returns {boolean} The flag which shows `super()` is called in some paths
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*/
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function isCalledInSomePath(segment) {
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return segment.reachable && segInfoMap[segment.id].calledInSomePaths;
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}
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/**
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* Gets the flag which shows `super()` is called in all paths.
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* @param {CodePathSegment} segment A code path segment to get.
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* @returns {boolean} The flag which shows `super()` is called in all paths.
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*/
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function isCalledInEveryPath(segment) {
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/*
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* If specific segment is the looped segment of the current segment,
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* skip the segment.
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* If not skipped, this never becomes true after a loop.
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*/
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if (segment.nextSegments.length === 1 &&
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segment.nextSegments[0].isLoopedPrevSegment(segment)
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) {
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return true;
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}
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return segment.reachable && segInfoMap[segment.id].calledInEveryPaths;
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}
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return {
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/**
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* Stacks a constructor information.
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* @param {CodePath} codePath A code path which was started.
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* @param {ASTNode} node The current node.
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* @returns {void}
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*/
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onCodePathStart(codePath, node) {
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if (isConstructorFunction(node)) {
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// Class > ClassBody > MethodDefinition > FunctionExpression
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const classNode = node.parent.parent.parent;
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const superClass = classNode.superClass;
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funcInfo = {
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upper: funcInfo,
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isConstructor: true,
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hasExtends: Boolean(superClass),
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superIsConstructor: isPossibleConstructor(superClass),
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codePath
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};
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} else {
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funcInfo = {
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upper: funcInfo,
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isConstructor: false,
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hasExtends: false,
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superIsConstructor: false,
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codePath
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};
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}
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},
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/**
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* Pops a constructor information.
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* And reports if `super()` lacked.
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* @param {CodePath} codePath A code path which was ended.
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* @param {ASTNode} node The current node.
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* @returns {void}
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*/
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onCodePathEnd(codePath, node) {
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const hasExtends = funcInfo.hasExtends;
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// Pop.
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funcInfo = funcInfo.upper;
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if (!hasExtends) {
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return;
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}
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// Reports if `super()` lacked.
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const segments = codePath.returnedSegments;
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const calledInEveryPaths = segments.every(isCalledInEveryPath);
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const calledInSomePaths = segments.some(isCalledInSomePath);
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if (!calledInEveryPaths) {
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context.report({
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messageId: calledInSomePaths
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? "missingSome"
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: "missingAll",
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node: node.parent
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});
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}
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},
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/**
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* Initialize information of a given code path segment.
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* @param {CodePathSegment} segment A code path segment to initialize.
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* @returns {void}
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*/
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onCodePathSegmentStart(segment) {
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if (!(funcInfo && funcInfo.isConstructor && funcInfo.hasExtends)) {
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return;
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}
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// Initialize info.
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const info = segInfoMap[segment.id] = {
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calledInSomePaths: false,
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calledInEveryPaths: false,
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validNodes: []
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};
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// When there are previous segments, aggregates these.
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const prevSegments = segment.prevSegments;
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if (prevSegments.length > 0) {
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info.calledInSomePaths = prevSegments.some(isCalledInSomePath);
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info.calledInEveryPaths = prevSegments.every(isCalledInEveryPath);
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}
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},
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/**
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* Update information of the code path segment when a code path was
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* looped.
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* @param {CodePathSegment} fromSegment The code path segment of the
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* end of a loop.
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* @param {CodePathSegment} toSegment A code path segment of the head
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* of a loop.
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* @returns {void}
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*/
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onCodePathSegmentLoop(fromSegment, toSegment) {
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if (!(funcInfo && funcInfo.isConstructor && funcInfo.hasExtends)) {
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return;
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}
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// Update information inside of the loop.
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const isRealLoop = toSegment.prevSegments.length >= 2;
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funcInfo.codePath.traverseSegments(
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{ first: toSegment, last: fromSegment },
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segment => {
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const info = segInfoMap[segment.id];
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const prevSegments = segment.prevSegments;
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// Updates flags.
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info.calledInSomePaths = prevSegments.some(isCalledInSomePath);
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info.calledInEveryPaths = prevSegments.every(isCalledInEveryPath);
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// If flags become true anew, reports the valid nodes.
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if (info.calledInSomePaths || isRealLoop) {
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const nodes = info.validNodes;
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info.validNodes = [];
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for (let i = 0; i < nodes.length; ++i) {
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const node = nodes[i];
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context.report({
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messageId: "duplicate",
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node
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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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* Checks for a call of `super()`.
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* @param {ASTNode} node A CallExpression node to check.
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* @returns {void}
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*/
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"CallExpression:exit"(node) {
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if (!(funcInfo && funcInfo.isConstructor)) {
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return;
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}
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// Skips except `super()`.
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if (node.callee.type !== "Super") {
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return;
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}
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// Reports if needed.
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if (funcInfo.hasExtends) {
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const segments = funcInfo.codePath.currentSegments;
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let duplicate = false;
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let info = null;
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for (let i = 0; i < segments.length; ++i) {
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const segment = segments[i];
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if (segment.reachable) {
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info = segInfoMap[segment.id];
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duplicate = duplicate || info.calledInSomePaths;
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info.calledInSomePaths = info.calledInEveryPaths = true;
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}
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}
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if (info) {
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if (duplicate) {
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context.report({
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messageId: "duplicate",
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node
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});
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} else if (!funcInfo.superIsConstructor) {
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context.report({
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messageId: "badSuper",
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node
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});
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} else {
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info.validNodes.push(node);
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}
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}
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} else if (funcInfo.codePath.currentSegments.some(isReachable)) {
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context.report({
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messageId: "unexpected",
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node
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});
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}
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},
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/**
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* Set the mark to the returned path as `super()` was called.
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* @param {ASTNode} node A ReturnStatement node to check.
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* @returns {void}
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*/
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ReturnStatement(node) {
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if (!(funcInfo && funcInfo.isConstructor && funcInfo.hasExtends)) {
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return;
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}
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// Skips if no argument.
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if (!node.argument) {
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return;
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}
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// Returning argument is a substitute of 'super()'.
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const segments = funcInfo.codePath.currentSegments;
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for (let i = 0; i < segments.length; ++i) {
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const segment = segments[i];
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if (segment.reachable) {
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const info = segInfoMap[segment.id];
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info.calledInSomePaths = info.calledInEveryPaths = true;
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}
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}
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},
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/**
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* Resets state.
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* @returns {void}
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*/
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"Program:exit"() {
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segInfoMap = Object.create(null);
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}
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};
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}
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};
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