305 lines
10 KiB
JavaScript
305 lines
10 KiB
JavaScript
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/**
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* @fileoverview A rule to disallow using `this`/`super` before `super()`.
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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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// Requirements
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//------------------------------------------------------------------------------
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const astUtils = require("./utils/ast-utils");
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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 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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// 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: "problem",
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docs: {
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description: "disallow `this`/`super` before calling `super()` in constructors",
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recommended: true,
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url: "https://eslint.org/docs/rules/no-this-before-super"
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},
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schema: [],
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messages: {
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noBeforeSuper: "'{{kind}}' is not allowed before 'super()'."
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}
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},
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create(context) {
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/*
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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 the owner class has a valid
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* `extends` part.
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* - scope: The scope of the owner class.
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* - codePath: The code path of this constructor.
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*/
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let funcInfo = null;
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/*
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* Information for each code path segment.
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* Each key is the id of a code path segment.
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* Each value is an object:
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* - superCalled: The flag which shows `super()` called in all code paths.
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* - invalidNodes: The array of invalid ThisExpression and Super nodes.
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*/
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let segInfoMap = Object.create(null);
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/**
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* Gets whether or not `super()` is called in a given code path segment.
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* @param {CodePathSegment} segment A code path segment to get.
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* @returns {boolean} `true` if `super()` is called.
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*/
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function isCalled(segment) {
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return !segment.reachable || segInfoMap[segment.id].superCalled;
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}
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/**
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* Checks whether or not this is in a constructor.
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* @returns {boolean} `true` if this is in a constructor.
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*/
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function isInConstructorOfDerivedClass() {
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return Boolean(funcInfo && funcInfo.isConstructor && funcInfo.hasExtends);
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}
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/**
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* Checks whether or not this is before `super()` is called.
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* @returns {boolean} `true` if this is before `super()` is called.
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*/
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function isBeforeCallOfSuper() {
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return (
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isInConstructorOfDerivedClass() &&
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!funcInfo.codePath.currentSegments.every(isCalled)
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);
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}
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/**
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* Sets a given node as invalid.
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* @param {ASTNode} node A node to set as invalid. This is one of
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* a ThisExpression and a Super.
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* @returns {void}
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*/
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function setInvalid(node) {
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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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segInfoMap[segment.id].invalidNodes.push(node);
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}
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}
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}
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/**
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* Sets the current segment as `super` was called.
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* @returns {void}
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*/
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function setSuperCalled() {
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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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segInfoMap[segment.id].superCalled = true;
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}
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}
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}
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return {
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/**
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* Adds information of a constructor into the stack.
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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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funcInfo = {
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upper: funcInfo,
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isConstructor: true,
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hasExtends: Boolean(
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classNode.superClass &&
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!astUtils.isNullOrUndefined(classNode.superClass)
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),
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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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codePath
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};
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}
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},
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/**
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* Removes the top of stack item.
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*
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* And this traverses all segments of this code path then reports every
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* invalid node.
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* @param {CodePath} codePath A code path which was ended.
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* @returns {void}
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*/
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onCodePathEnd(codePath) {
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const isDerivedClass = funcInfo.hasExtends;
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funcInfo = funcInfo.upper;
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if (!isDerivedClass) {
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return;
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}
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codePath.traverseSegments((segment, controller) => {
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const info = segInfoMap[segment.id];
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for (let i = 0; i < info.invalidNodes.length; ++i) {
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const invalidNode = info.invalidNodes[i];
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context.report({
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messageId: "noBeforeSuper",
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node: invalidNode,
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data: {
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kind: invalidNode.type === "Super" ? "super" : "this"
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}
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});
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}
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if (info.superCalled) {
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controller.skip();
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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 (!isInConstructorOfDerivedClass()) {
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return;
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}
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// Initialize info.
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segInfoMap[segment.id] = {
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superCalled: (
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segment.prevSegments.length > 0 &&
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segment.prevSegments.every(isCalled)
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),
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invalidNodes: []
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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 (!isInConstructorOfDerivedClass()) {
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return;
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}
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// Update information inside of the loop.
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funcInfo.codePath.traverseSegments(
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{ first: toSegment, last: fromSegment },
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(segment, controller) => {
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const info = segInfoMap[segment.id];
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if (info.superCalled) {
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info.invalidNodes = [];
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controller.skip();
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} else if (
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segment.prevSegments.length > 0 &&
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segment.prevSegments.every(isCalled)
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) {
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info.superCalled = true;
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info.invalidNodes = [];
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}
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}
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);
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},
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/**
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* Reports if this is before `super()`.
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* @param {ASTNode} node A target node.
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* @returns {void}
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*/
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ThisExpression(node) {
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if (isBeforeCallOfSuper()) {
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setInvalid(node);
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}
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},
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/**
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* Reports if this is before `super()`.
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* @param {ASTNode} node A target node.
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* @returns {void}
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*/
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Super(node) {
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if (!astUtils.isCallee(node) && isBeforeCallOfSuper()) {
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setInvalid(node);
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}
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},
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/**
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* Marks `super()` called.
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* @param {ASTNode} node A target node.
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* @returns {void}
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*/
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"CallExpression:exit"(node) {
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if (node.callee.type === "Super" && isBeforeCallOfSuper()) {
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setSuperCalled();
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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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