684 lines
20 KiB
JavaScript
684 lines
20 KiB
JavaScript
/**
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* @fileoverview A class of the code path analyzer.
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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 assert = require("assert"),
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{ breakableTypePattern } = require("../../shared/ast-utils"),
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CodePath = require("./code-path"),
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CodePathSegment = require("./code-path-segment"),
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IdGenerator = require("./id-generator"),
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debug = require("./debug-helpers");
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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 `case` node (not `default` node).
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* @param {ASTNode} node A `SwitchCase` node to check.
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* @returns {boolean} `true` if the node is a `case` node (not `default` node).
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*/
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function isCaseNode(node) {
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return Boolean(node.test);
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}
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/**
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* Checks whether the given logical operator is taken into account for the code
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* path analysis.
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* @param {string} operator The operator found in the LogicalExpression node
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* @returns {boolean} `true` if the operator is "&&" or "||"
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*/
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function isHandledLogicalOperator(operator) {
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return operator === "&&" || operator === "||";
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}
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/**
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* Gets the label if the parent node of a given node is a LabeledStatement.
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* @param {ASTNode} node A node to get.
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* @returns {string|null} The label or `null`.
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*/
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function getLabel(node) {
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if (node.parent.type === "LabeledStatement") {
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return node.parent.label.name;
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}
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return null;
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}
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/**
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* Checks whether or not a given logical expression node goes different path
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* between the `true` case and the `false` case.
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* @param {ASTNode} node A node to check.
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* @returns {boolean} `true` if the node is a test of a choice statement.
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*/
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function isForkingByTrueOrFalse(node) {
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const parent = node.parent;
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switch (parent.type) {
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case "ConditionalExpression":
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case "IfStatement":
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case "WhileStatement":
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case "DoWhileStatement":
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case "ForStatement":
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return parent.test === node;
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case "LogicalExpression":
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return isHandledLogicalOperator(parent.operator);
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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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* Gets the boolean value of a given literal node.
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*
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* This is used to detect infinity loops (e.g. `while (true) {}`).
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* Statements preceded by an infinity loop are unreachable if the loop didn't
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* have any `break` statement.
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* @param {ASTNode} node A node to get.
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* @returns {boolean|undefined} a boolean value if the node is a Literal node,
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* otherwise `undefined`.
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*/
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function getBooleanValueIfSimpleConstant(node) {
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if (node.type === "Literal") {
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return Boolean(node.value);
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}
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return void 0;
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}
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/**
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* Checks that a given identifier node is a reference or not.
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*
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* This is used to detect the first throwable node in a `try` block.
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* @param {ASTNode} node An Identifier node to check.
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* @returns {boolean} `true` if the node is a reference.
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*/
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function isIdentifierReference(node) {
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const parent = node.parent;
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switch (parent.type) {
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case "LabeledStatement":
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case "BreakStatement":
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case "ContinueStatement":
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case "ArrayPattern":
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case "RestElement":
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case "ImportSpecifier":
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case "ImportDefaultSpecifier":
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case "ImportNamespaceSpecifier":
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case "CatchClause":
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return false;
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case "FunctionDeclaration":
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case "FunctionExpression":
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case "ArrowFunctionExpression":
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case "ClassDeclaration":
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case "ClassExpression":
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case "VariableDeclarator":
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return parent.id !== node;
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case "Property":
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case "MethodDefinition":
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return (
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parent.key !== node ||
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parent.computed ||
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parent.shorthand
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);
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case "AssignmentPattern":
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return parent.key !== node;
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default:
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return true;
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}
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}
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/**
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* Updates the current segment with the head segment.
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* This is similar to local branches and tracking branches of git.
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*
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* To separate the current and the head is in order to not make useless segments.
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*
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* In this process, both "onCodePathSegmentStart" and "onCodePathSegmentEnd"
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* events are fired.
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* @param {CodePathAnalyzer} analyzer The instance.
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* @param {ASTNode} node The current AST node.
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* @returns {void}
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*/
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function forwardCurrentToHead(analyzer, node) {
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const codePath = analyzer.codePath;
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const state = CodePath.getState(codePath);
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const currentSegments = state.currentSegments;
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const headSegments = state.headSegments;
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const end = Math.max(currentSegments.length, headSegments.length);
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let i, currentSegment, headSegment;
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// Fires leaving events.
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for (i = 0; i < end; ++i) {
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currentSegment = currentSegments[i];
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headSegment = headSegments[i];
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if (currentSegment !== headSegment && currentSegment) {
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debug.dump(`onCodePathSegmentEnd ${currentSegment.id}`);
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if (currentSegment.reachable) {
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analyzer.emitter.emit(
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"onCodePathSegmentEnd",
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currentSegment,
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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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// Update state.
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state.currentSegments = headSegments;
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// Fires entering events.
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for (i = 0; i < end; ++i) {
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currentSegment = currentSegments[i];
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headSegment = headSegments[i];
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if (currentSegment !== headSegment && headSegment) {
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debug.dump(`onCodePathSegmentStart ${headSegment.id}`);
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CodePathSegment.markUsed(headSegment);
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if (headSegment.reachable) {
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analyzer.emitter.emit(
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"onCodePathSegmentStart",
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headSegment,
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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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* Updates the current segment with empty.
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* This is called at the last of functions or the program.
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* @param {CodePathAnalyzer} analyzer The instance.
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* @param {ASTNode} node The current AST node.
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* @returns {void}
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*/
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function leaveFromCurrentSegment(analyzer, node) {
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const state = CodePath.getState(analyzer.codePath);
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const currentSegments = state.currentSegments;
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for (let i = 0; i < currentSegments.length; ++i) {
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const currentSegment = currentSegments[i];
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debug.dump(`onCodePathSegmentEnd ${currentSegment.id}`);
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if (currentSegment.reachable) {
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analyzer.emitter.emit(
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"onCodePathSegmentEnd",
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currentSegment,
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node
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);
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}
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}
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state.currentSegments = [];
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}
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/**
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* Updates the code path due to the position of a given node in the parent node
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* thereof.
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*
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* For example, if the node is `parent.consequent`, this creates a fork from the
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* current path.
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* @param {CodePathAnalyzer} analyzer The instance.
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* @param {ASTNode} node The current AST node.
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* @returns {void}
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*/
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function preprocess(analyzer, node) {
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const codePath = analyzer.codePath;
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const state = CodePath.getState(codePath);
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const parent = node.parent;
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switch (parent.type) {
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case "LogicalExpression":
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if (
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parent.right === node &&
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isHandledLogicalOperator(parent.operator)
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) {
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state.makeLogicalRight();
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}
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break;
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case "ConditionalExpression":
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case "IfStatement":
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/*
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* Fork if this node is at `consequent`/`alternate`.
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* `popForkContext()` exists at `IfStatement:exit` and
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* `ConditionalExpression:exit`.
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*/
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if (parent.consequent === node) {
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state.makeIfConsequent();
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} else if (parent.alternate === node) {
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state.makeIfAlternate();
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}
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break;
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case "SwitchCase":
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if (parent.consequent[0] === node) {
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state.makeSwitchCaseBody(false, !parent.test);
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}
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break;
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case "TryStatement":
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if (parent.handler === node) {
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state.makeCatchBlock();
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} else if (parent.finalizer === node) {
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state.makeFinallyBlock();
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}
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break;
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case "WhileStatement":
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if (parent.test === node) {
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state.makeWhileTest(getBooleanValueIfSimpleConstant(node));
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} else {
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assert(parent.body === node);
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state.makeWhileBody();
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}
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break;
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case "DoWhileStatement":
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if (parent.body === node) {
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state.makeDoWhileBody();
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} else {
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assert(parent.test === node);
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state.makeDoWhileTest(getBooleanValueIfSimpleConstant(node));
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}
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break;
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case "ForStatement":
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if (parent.test === node) {
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state.makeForTest(getBooleanValueIfSimpleConstant(node));
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} else if (parent.update === node) {
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state.makeForUpdate();
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} else if (parent.body === node) {
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state.makeForBody();
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}
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break;
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case "ForInStatement":
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case "ForOfStatement":
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if (parent.left === node) {
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state.makeForInOfLeft();
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} else if (parent.right === node) {
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state.makeForInOfRight();
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} else {
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assert(parent.body === node);
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state.makeForInOfBody();
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}
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break;
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case "AssignmentPattern":
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/*
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* Fork if this node is at `right`.
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* `left` is executed always, so it uses the current path.
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* `popForkContext()` exists at `AssignmentPattern:exit`.
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*/
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if (parent.right === node) {
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state.pushForkContext();
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state.forkBypassPath();
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state.forkPath();
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}
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break;
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default:
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break;
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}
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}
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/**
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* Updates the code path due to the type of a given node in entering.
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* @param {CodePathAnalyzer} analyzer The instance.
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* @param {ASTNode} node The current AST node.
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* @returns {void}
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*/
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function processCodePathToEnter(analyzer, node) {
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let codePath = analyzer.codePath;
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let state = codePath && CodePath.getState(codePath);
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const parent = node.parent;
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switch (node.type) {
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case "Program":
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case "FunctionDeclaration":
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case "FunctionExpression":
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case "ArrowFunctionExpression":
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if (codePath) {
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// Emits onCodePathSegmentStart events if updated.
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forwardCurrentToHead(analyzer, node);
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debug.dumpState(node, state, false);
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}
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// Create the code path of this scope.
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codePath = analyzer.codePath = new CodePath(
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analyzer.idGenerator.next(),
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codePath,
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analyzer.onLooped
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);
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state = CodePath.getState(codePath);
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// Emits onCodePathStart events.
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debug.dump(`onCodePathStart ${codePath.id}`);
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analyzer.emitter.emit("onCodePathStart", codePath, node);
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break;
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case "LogicalExpression":
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if (isHandledLogicalOperator(node.operator)) {
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state.pushChoiceContext(
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node.operator,
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isForkingByTrueOrFalse(node)
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);
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}
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break;
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case "ConditionalExpression":
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case "IfStatement":
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state.pushChoiceContext("test", false);
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break;
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case "SwitchStatement":
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state.pushSwitchContext(
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node.cases.some(isCaseNode),
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getLabel(node)
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);
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break;
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case "TryStatement":
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state.pushTryContext(Boolean(node.finalizer));
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break;
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case "SwitchCase":
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/*
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* Fork if this node is after the 2st node in `cases`.
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* It's similar to `else` blocks.
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* The next `test` node is processed in this path.
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*/
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if (parent.discriminant !== node && parent.cases[0] !== node) {
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state.forkPath();
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}
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break;
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case "WhileStatement":
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case "DoWhileStatement":
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case "ForStatement":
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case "ForInStatement":
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case "ForOfStatement":
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state.pushLoopContext(node.type, getLabel(node));
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break;
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case "LabeledStatement":
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if (!breakableTypePattern.test(node.body.type)) {
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state.pushBreakContext(false, node.label.name);
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}
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break;
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default:
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break;
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}
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// Emits onCodePathSegmentStart events if updated.
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forwardCurrentToHead(analyzer, node);
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debug.dumpState(node, state, false);
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}
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/**
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* Updates the code path due to the type of a given node in leaving.
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* @param {CodePathAnalyzer} analyzer The instance.
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* @param {ASTNode} node The current AST node.
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* @returns {void}
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*/
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function processCodePathToExit(analyzer, node) {
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const codePath = analyzer.codePath;
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const state = CodePath.getState(codePath);
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let dontForward = false;
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switch (node.type) {
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case "IfStatement":
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case "ConditionalExpression":
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state.popChoiceContext();
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break;
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case "LogicalExpression":
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if (isHandledLogicalOperator(node.operator)) {
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state.popChoiceContext();
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}
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break;
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case "SwitchStatement":
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state.popSwitchContext();
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break;
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case "SwitchCase":
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/*
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* This is the same as the process at the 1st `consequent` node in
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* `preprocess` function.
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* Must do if this `consequent` is empty.
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*/
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if (node.consequent.length === 0) {
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state.makeSwitchCaseBody(true, !node.test);
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}
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if (state.forkContext.reachable) {
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dontForward = true;
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}
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break;
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case "TryStatement":
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state.popTryContext();
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break;
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case "BreakStatement":
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forwardCurrentToHead(analyzer, node);
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state.makeBreak(node.label && node.label.name);
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dontForward = true;
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break;
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case "ContinueStatement":
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forwardCurrentToHead(analyzer, node);
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state.makeContinue(node.label && node.label.name);
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dontForward = true;
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break;
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case "ReturnStatement":
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forwardCurrentToHead(analyzer, node);
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state.makeReturn();
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dontForward = true;
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break;
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case "ThrowStatement":
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forwardCurrentToHead(analyzer, node);
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state.makeThrow();
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dontForward = true;
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break;
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case "Identifier":
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if (isIdentifierReference(node)) {
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state.makeFirstThrowablePathInTryBlock();
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dontForward = true;
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}
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break;
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case "CallExpression":
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case "ImportExpression":
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case "MemberExpression":
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case "NewExpression":
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state.makeFirstThrowablePathInTryBlock();
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break;
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case "WhileStatement":
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case "DoWhileStatement":
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case "ForStatement":
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case "ForInStatement":
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case "ForOfStatement":
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state.popLoopContext();
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break;
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case "AssignmentPattern":
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state.popForkContext();
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break;
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case "LabeledStatement":
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if (!breakableTypePattern.test(node.body.type)) {
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state.popBreakContext();
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}
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break;
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default:
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break;
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}
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// Emits onCodePathSegmentStart events if updated.
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if (!dontForward) {
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forwardCurrentToHead(analyzer, node);
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}
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debug.dumpState(node, state, true);
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}
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/**
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* Updates the code path to finalize the current code path.
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* @param {CodePathAnalyzer} analyzer The instance.
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* @param {ASTNode} node The current AST node.
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* @returns {void}
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*/
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function postprocess(analyzer, node) {
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switch (node.type) {
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case "Program":
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case "FunctionDeclaration":
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case "FunctionExpression":
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case "ArrowFunctionExpression": {
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let codePath = analyzer.codePath;
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// Mark the current path as the final node.
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CodePath.getState(codePath).makeFinal();
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// Emits onCodePathSegmentEnd event of the current segments.
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leaveFromCurrentSegment(analyzer, node);
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// Emits onCodePathEnd event of this code path.
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debug.dump(`onCodePathEnd ${codePath.id}`);
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analyzer.emitter.emit("onCodePathEnd", codePath, node);
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debug.dumpDot(codePath);
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codePath = analyzer.codePath = analyzer.codePath.upper;
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if (codePath) {
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debug.dumpState(node, CodePath.getState(codePath), true);
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}
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break;
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}
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default:
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break;
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}
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}
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//------------------------------------------------------------------------------
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// Public Interface
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//------------------------------------------------------------------------------
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|
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/**
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* The class to analyze code paths.
|
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* This class implements the EventGenerator interface.
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*/
|
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class CodePathAnalyzer {
|
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// eslint-disable-next-line jsdoc/require-description
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/**
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* @param {EventGenerator} eventGenerator An event generator to wrap.
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*/
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constructor(eventGenerator) {
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this.original = eventGenerator;
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this.emitter = eventGenerator.emitter;
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this.codePath = null;
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this.idGenerator = new IdGenerator("s");
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this.currentNode = null;
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this.onLooped = this.onLooped.bind(this);
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}
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/**
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* Does the process to enter a given AST node.
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* This updates state of analysis and calls `enterNode` of the wrapped.
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* @param {ASTNode} node A node which is entering.
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* @returns {void}
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*/
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enterNode(node) {
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this.currentNode = node;
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// Updates the code path due to node's position in its parent node.
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if (node.parent) {
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preprocess(this, node);
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}
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/*
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* Updates the code path.
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* And emits onCodePathStart/onCodePathSegmentStart events.
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*/
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processCodePathToEnter(this, node);
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// Emits node events.
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this.original.enterNode(node);
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this.currentNode = null;
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}
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/**
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* Does the process to leave a given AST node.
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* This updates state of analysis and calls `leaveNode` of the wrapped.
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* @param {ASTNode} node A node which is leaving.
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* @returns {void}
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*/
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leaveNode(node) {
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this.currentNode = node;
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/*
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* Updates the code path.
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* And emits onCodePathStart/onCodePathSegmentStart events.
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*/
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processCodePathToExit(this, node);
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// Emits node events.
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this.original.leaveNode(node);
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// Emits the last onCodePathStart/onCodePathSegmentStart events.
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postprocess(this, node);
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this.currentNode = null;
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}
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/**
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* This is called on a code path looped.
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* Then this raises a looped event.
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* @param {CodePathSegment} fromSegment A segment of prev.
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* @param {CodePathSegment} toSegment A segment of next.
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* @returns {void}
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*/
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onLooped(fromSegment, toSegment) {
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if (fromSegment.reachable && toSegment.reachable) {
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debug.dump(`onCodePathSegmentLoop ${fromSegment.id} -> ${toSegment.id}`);
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this.emitter.emit(
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"onCodePathSegmentLoop",
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fromSegment,
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toSegment,
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this.currentNode
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);
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}
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}
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}
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module.exports = CodePathAnalyzer;
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