853 lines
25 KiB
JavaScript
853 lines
25 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 if a given node appears as the value of a PropertyDefinition node.
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* @param {ASTNode} node THe node to check.
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* @returns {boolean} `true` if the node is a PropertyDefinition value,
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* false if not.
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*/
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function isPropertyDefinitionValue(node) {
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const parent = node.parent;
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return parent && parent.type === "PropertyDefinition" && parent.value === node;
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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 "||" or "??"
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*/
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function isHandledLogicalOperator(operator) {
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return operator === "&&" || operator === "||" || operator === "??";
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}
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/**
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* Checks whether the given assignment operator is a logical assignment operator.
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* Logical assignments are taken into account for the code path analysis
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* because of their short-circuiting semantics.
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* @param {string} operator The operator found in the AssignmentExpression node
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* @returns {boolean} `true` if the operator is "&&=" or "||=" or "??="
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*/
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function isLogicalAssignmentOperator(operator) {
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return operator === "&&=" || 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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case "AssignmentExpression":
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return isLogicalAssignmentOperator(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 "PropertyDefinition":
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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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const eventName = currentSegment.reachable
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? "onCodePathSegmentEnd"
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: "onUnreachableCodePathSegmentEnd";
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debug.dump(`${eventName} ${currentSegment.id}`);
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analyzer.emitter.emit(
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eventName,
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currentSegment,
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node
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);
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}
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}
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// Update state.
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state.currentSegments = headSegments;
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// Fires entering events.
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for (i = 0; i < end; ++i) {
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currentSegment = currentSegments[i];
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headSegment = headSegments[i];
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if (currentSegment !== headSegment && headSegment) {
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const eventName = headSegment.reachable
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? "onCodePathSegmentStart"
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: "onUnreachableCodePathSegmentStart";
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debug.dump(`${eventName} ${headSegment.id}`);
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CodePathSegment.markUsed(headSegment);
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analyzer.emitter.emit(
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eventName,
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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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* 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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const eventName = currentSegment.reachable
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? "onCodePathSegmentEnd"
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: "onUnreachableCodePathSegmentEnd";
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debug.dump(`${eventName} ${currentSegment.id}`);
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analyzer.emitter.emit(
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eventName,
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currentSegment,
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node
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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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// The `arguments.length == 0` case is in `postprocess` function.
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case "CallExpression":
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if (parent.optional === true && parent.arguments.length >= 1 && parent.arguments[0] === node) {
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state.makeOptionalRight();
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}
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break;
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case "MemberExpression":
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if (parent.optional === true && parent.property === node) {
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state.makeOptionalRight();
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}
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break;
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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 "AssignmentExpression":
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if (
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parent.right === node &&
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isLogicalAssignmentOperator(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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/**
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* Creates a new code path and trigger the onCodePathStart event
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* based on the currently selected node.
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* @param {string} origin The reason the code path was started.
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* @returns {void}
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*/
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function startCodePath(origin) {
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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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id: analyzer.idGenerator.next(),
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origin,
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upper: codePath,
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onLooped: 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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}
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/*
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* Special case: The right side of class field initializer is considered
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* to be its own function, so we need to start a new code path in this
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* case.
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*/
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if (isPropertyDefinitionValue(node)) {
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startCodePath("class-field-initializer");
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/*
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* Intentional fall through because `node` needs to also be
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* processed by the code below. For example, if we have:
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*
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* class Foo {
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* a = () => {}
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* }
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*
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* In this case, we also need start a second code path.
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*/
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}
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switch (node.type) {
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case "Program":
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startCodePath("program");
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break;
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case "FunctionDeclaration":
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case "FunctionExpression":
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case "ArrowFunctionExpression":
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startCodePath("function");
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break;
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case "StaticBlock":
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startCodePath("class-static-block");
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break;
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case "ChainExpression":
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state.pushChainContext();
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break;
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case "CallExpression":
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if (node.optional === true) {
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state.makeOptionalNode();
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}
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break;
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case "MemberExpression":
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if (node.optional === true) {
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state.makeOptionalNode();
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}
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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 "AssignmentExpression":
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if (isLogicalAssignmentOperator(node.operator)) {
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state.pushChoiceContext(
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node.operator.slice(0, -1), // removes `=` from the end
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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 "ChainExpression":
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state.popChainContext();
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break;
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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 "AssignmentExpression":
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if (isLogicalAssignmentOperator(node.operator)) {
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state.popChoiceContext();
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}
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break;
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case "SwitchStatement":
|
|
state.popSwitchContext();
|
|
break;
|
|
|
|
case "SwitchCase":
|
|
|
|
/*
|
|
* This is the same as the process at the 1st `consequent` node in
|
|
* `preprocess` function.
|
|
* Must do if this `consequent` is empty.
|
|
*/
|
|
if (node.consequent.length === 0) {
|
|
state.makeSwitchCaseBody(true, !node.test);
|
|
}
|
|
if (state.forkContext.reachable) {
|
|
dontForward = true;
|
|
}
|
|
break;
|
|
|
|
case "TryStatement":
|
|
state.popTryContext();
|
|
break;
|
|
|
|
case "BreakStatement":
|
|
forwardCurrentToHead(analyzer, node);
|
|
state.makeBreak(node.label && node.label.name);
|
|
dontForward = true;
|
|
break;
|
|
|
|
case "ContinueStatement":
|
|
forwardCurrentToHead(analyzer, node);
|
|
state.makeContinue(node.label && node.label.name);
|
|
dontForward = true;
|
|
break;
|
|
|
|
case "ReturnStatement":
|
|
forwardCurrentToHead(analyzer, node);
|
|
state.makeReturn();
|
|
dontForward = true;
|
|
break;
|
|
|
|
case "ThrowStatement":
|
|
forwardCurrentToHead(analyzer, node);
|
|
state.makeThrow();
|
|
dontForward = true;
|
|
break;
|
|
|
|
case "Identifier":
|
|
if (isIdentifierReference(node)) {
|
|
state.makeFirstThrowablePathInTryBlock();
|
|
dontForward = true;
|
|
}
|
|
break;
|
|
|
|
case "CallExpression":
|
|
case "ImportExpression":
|
|
case "MemberExpression":
|
|
case "NewExpression":
|
|
case "YieldExpression":
|
|
state.makeFirstThrowablePathInTryBlock();
|
|
break;
|
|
|
|
case "WhileStatement":
|
|
case "DoWhileStatement":
|
|
case "ForStatement":
|
|
case "ForInStatement":
|
|
case "ForOfStatement":
|
|
state.popLoopContext();
|
|
break;
|
|
|
|
case "AssignmentPattern":
|
|
state.popForkContext();
|
|
break;
|
|
|
|
case "LabeledStatement":
|
|
if (!breakableTypePattern.test(node.body.type)) {
|
|
state.popBreakContext();
|
|
}
|
|
break;
|
|
|
|
default:
|
|
break;
|
|
}
|
|
|
|
// Emits onCodePathSegmentStart events if updated.
|
|
if (!dontForward) {
|
|
forwardCurrentToHead(analyzer, node);
|
|
}
|
|
debug.dumpState(node, state, true);
|
|
}
|
|
|
|
/**
|
|
* Updates the code path to finalize the current code path.
|
|
* @param {CodePathAnalyzer} analyzer The instance.
|
|
* @param {ASTNode} node The current AST node.
|
|
* @returns {void}
|
|
*/
|
|
function postprocess(analyzer, node) {
|
|
|
|
/**
|
|
* Ends the code path for the current node.
|
|
* @returns {void}
|
|
*/
|
|
function endCodePath() {
|
|
let codePath = analyzer.codePath;
|
|
|
|
// Mark the current path as the final node.
|
|
CodePath.getState(codePath).makeFinal();
|
|
|
|
// Emits onCodePathSegmentEnd event of the current segments.
|
|
leaveFromCurrentSegment(analyzer, node);
|
|
|
|
// Emits onCodePathEnd event of this code path.
|
|
debug.dump(`onCodePathEnd ${codePath.id}`);
|
|
analyzer.emitter.emit("onCodePathEnd", codePath, node);
|
|
debug.dumpDot(codePath);
|
|
|
|
codePath = analyzer.codePath = analyzer.codePath.upper;
|
|
if (codePath) {
|
|
debug.dumpState(node, CodePath.getState(codePath), true);
|
|
}
|
|
|
|
}
|
|
|
|
switch (node.type) {
|
|
case "Program":
|
|
case "FunctionDeclaration":
|
|
case "FunctionExpression":
|
|
case "ArrowFunctionExpression":
|
|
case "StaticBlock": {
|
|
endCodePath();
|
|
break;
|
|
}
|
|
|
|
// The `arguments.length >= 1` case is in `preprocess` function.
|
|
case "CallExpression":
|
|
if (node.optional === true && node.arguments.length === 0) {
|
|
CodePath.getState(analyzer.codePath).makeOptionalRight();
|
|
}
|
|
break;
|
|
|
|
default:
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Special case: The right side of class field initializer is considered
|
|
* to be its own function, so we need to end a code path in this
|
|
* case.
|
|
*
|
|
* We need to check after the other checks in order to close the
|
|
* code paths in the correct order for code like this:
|
|
*
|
|
*
|
|
* class Foo {
|
|
* a = () => {}
|
|
* }
|
|
*
|
|
* In this case, The ArrowFunctionExpression code path is closed first
|
|
* and then we need to close the code path for the PropertyDefinition
|
|
* value.
|
|
*/
|
|
if (isPropertyDefinitionValue(node)) {
|
|
endCodePath();
|
|
}
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Public Interface
|
|
//------------------------------------------------------------------------------
|
|
|
|
/**
|
|
* The class to analyze code paths.
|
|
* This class implements the EventGenerator interface.
|
|
*/
|
|
class CodePathAnalyzer {
|
|
|
|
/**
|
|
* @param {EventGenerator} eventGenerator An event generator to wrap.
|
|
*/
|
|
constructor(eventGenerator) {
|
|
this.original = eventGenerator;
|
|
this.emitter = eventGenerator.emitter;
|
|
this.codePath = null;
|
|
this.idGenerator = new IdGenerator("s");
|
|
this.currentNode = null;
|
|
this.onLooped = this.onLooped.bind(this);
|
|
}
|
|
|
|
/**
|
|
* Does the process to enter a given AST node.
|
|
* This updates state of analysis and calls `enterNode` of the wrapped.
|
|
* @param {ASTNode} node A node which is entering.
|
|
* @returns {void}
|
|
*/
|
|
enterNode(node) {
|
|
this.currentNode = node;
|
|
|
|
// Updates the code path due to node's position in its parent node.
|
|
if (node.parent) {
|
|
preprocess(this, node);
|
|
}
|
|
|
|
/*
|
|
* Updates the code path.
|
|
* And emits onCodePathStart/onCodePathSegmentStart events.
|
|
*/
|
|
processCodePathToEnter(this, node);
|
|
|
|
// Emits node events.
|
|
this.original.enterNode(node);
|
|
|
|
this.currentNode = null;
|
|
}
|
|
|
|
/**
|
|
* Does the process to leave a given AST node.
|
|
* This updates state of analysis and calls `leaveNode` of the wrapped.
|
|
* @param {ASTNode} node A node which is leaving.
|
|
* @returns {void}
|
|
*/
|
|
leaveNode(node) {
|
|
this.currentNode = node;
|
|
|
|
/*
|
|
* Updates the code path.
|
|
* And emits onCodePathStart/onCodePathSegmentStart events.
|
|
*/
|
|
processCodePathToExit(this, node);
|
|
|
|
// Emits node events.
|
|
this.original.leaveNode(node);
|
|
|
|
// Emits the last onCodePathStart/onCodePathSegmentStart events.
|
|
postprocess(this, node);
|
|
|
|
this.currentNode = null;
|
|
}
|
|
|
|
/**
|
|
* This is called on a code path looped.
|
|
* Then this raises a looped event.
|
|
* @param {CodePathSegment} fromSegment A segment of prev.
|
|
* @param {CodePathSegment} toSegment A segment of next.
|
|
* @returns {void}
|
|
*/
|
|
onLooped(fromSegment, toSegment) {
|
|
if (fromSegment.reachable && toSegment.reachable) {
|
|
debug.dump(`onCodePathSegmentLoop ${fromSegment.id} -> ${toSegment.id}`);
|
|
this.emitter.emit(
|
|
"onCodePathSegmentLoop",
|
|
fromSegment,
|
|
toSegment,
|
|
this.currentNode
|
|
);
|
|
}
|
|
}
|
|
}
|
|
|
|
module.exports = CodePathAnalyzer;
|