Current File : /var/www/html/node_modules/eslint/lib/linter/code-path-analysis/code-path-analyzer.js
/**
* @fileoverview A class of the code path analyzer.
* @author Toru Nagashima
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const assert = require("assert"),
{ breakableTypePattern } = require("../../shared/ast-utils"),
CodePath = require("./code-path"),
CodePathSegment = require("./code-path-segment"),
IdGenerator = require("./id-generator"),
debug = require("./debug-helpers");
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
/**
* Checks whether or not a given node is a `case` node (not `default` node).
* @param {ASTNode} node A `SwitchCase` node to check.
* @returns {boolean} `true` if the node is a `case` node (not `default` node).
*/
function isCaseNode(node) {
return Boolean(node.test);
}
/**
* Checks if a given node appears as the value of a PropertyDefinition node.
* @param {ASTNode} node THe node to check.
* @returns {boolean} `true` if the node is a PropertyDefinition value,
* false if not.
*/
function isPropertyDefinitionValue(node) {
const parent = node.parent;
return parent && parent.type === "PropertyDefinition" && parent.value === node;
}
/**
* Checks whether the given logical operator is taken into account for the code
* path analysis.
* @param {string} operator The operator found in the LogicalExpression node
* @returns {boolean} `true` if the operator is "&&" or "||" or "??"
*/
function isHandledLogicalOperator(operator) {
return operator === "&&" || operator === "||" || operator === "??";
}
/**
* Checks whether the given assignment operator is a logical assignment operator.
* Logical assignments are taken into account for the code path analysis
* because of their short-circuiting semantics.
* @param {string} operator The operator found in the AssignmentExpression node
* @returns {boolean} `true` if the operator is "&&=" or "||=" or "??="
*/
function isLogicalAssignmentOperator(operator) {
return operator === "&&=" || operator === "||=" || operator === "??=";
}
/**
* Gets the label if the parent node of a given node is a LabeledStatement.
* @param {ASTNode} node A node to get.
* @returns {string|null} The label or `null`.
*/
function getLabel(node) {
if (node.parent.type === "LabeledStatement") {
return node.parent.label.name;
}
return null;
}
/**
* Checks whether or not a given logical expression node goes different path
* between the `true` case and the `false` case.
* @param {ASTNode} node A node to check.
* @returns {boolean} `true` if the node is a test of a choice statement.
*/
function isForkingByTrueOrFalse(node) {
const parent = node.parent;
switch (parent.type) {
case "ConditionalExpression":
case "IfStatement":
case "WhileStatement":
case "DoWhileStatement":
case "ForStatement":
return parent.test === node;
case "LogicalExpression":
return isHandledLogicalOperator(parent.operator);
case "AssignmentExpression":
return isLogicalAssignmentOperator(parent.operator);
default:
return false;
}
}
/**
* Gets the boolean value of a given literal node.
*
* This is used to detect infinity loops (e.g. `while (true) {}`).
* Statements preceded by an infinity loop are unreachable if the loop didn't
* have any `break` statement.
* @param {ASTNode} node A node to get.
* @returns {boolean|undefined} a boolean value if the node is a Literal node,
* otherwise `undefined`.
*/
function getBooleanValueIfSimpleConstant(node) {
if (node.type === "Literal") {
return Boolean(node.value);
}
return void 0;
}
/**
* Checks that a given identifier node is a reference or not.
*
* This is used to detect the first throwable node in a `try` block.
* @param {ASTNode} node An Identifier node to check.
* @returns {boolean} `true` if the node is a reference.
*/
function isIdentifierReference(node) {
const parent = node.parent;
switch (parent.type) {
case "LabeledStatement":
case "BreakStatement":
case "ContinueStatement":
case "ArrayPattern":
case "RestElement":
case "ImportSpecifier":
case "ImportDefaultSpecifier":
case "ImportNamespaceSpecifier":
case "CatchClause":
return false;
case "FunctionDeclaration":
case "FunctionExpression":
case "ArrowFunctionExpression":
case "ClassDeclaration":
case "ClassExpression":
case "VariableDeclarator":
return parent.id !== node;
case "Property":
case "PropertyDefinition":
case "MethodDefinition":
return (
parent.key !== node ||
parent.computed ||
parent.shorthand
);
case "AssignmentPattern":
return parent.key !== node;
default:
return true;
}
}
/**
* Updates the current segment with the head segment.
* This is similar to local branches and tracking branches of git.
*
* To separate the current and the head is in order to not make useless segments.
*
* In this process, both "onCodePathSegmentStart" and "onCodePathSegmentEnd"
* events are fired.
* @param {CodePathAnalyzer} analyzer The instance.
* @param {ASTNode} node The current AST node.
* @returns {void}
*/
function forwardCurrentToHead(analyzer, node) {
const codePath = analyzer.codePath;
const state = CodePath.getState(codePath);
const currentSegments = state.currentSegments;
const headSegments = state.headSegments;
const end = Math.max(currentSegments.length, headSegments.length);
let i, currentSegment, headSegment;
// Fires leaving events.
for (i = 0; i < end; ++i) {
currentSegment = currentSegments[i];
headSegment = headSegments[i];
if (currentSegment !== headSegment && currentSegment) {
debug.dump(`onCodePathSegmentEnd ${currentSegment.id}`);
if (currentSegment.reachable) {
analyzer.emitter.emit(
"onCodePathSegmentEnd",
currentSegment,
node
);
}
}
}
// Update state.
state.currentSegments = headSegments;
// Fires entering events.
for (i = 0; i < end; ++i) {
currentSegment = currentSegments[i];
headSegment = headSegments[i];
if (currentSegment !== headSegment && headSegment) {
debug.dump(`onCodePathSegmentStart ${headSegment.id}`);
CodePathSegment.markUsed(headSegment);
if (headSegment.reachable) {
analyzer.emitter.emit(
"onCodePathSegmentStart",
headSegment,
node
);
}
}
}
}
/**
* Updates the current segment with empty.
* This is called at the last of functions or the program.
* @param {CodePathAnalyzer} analyzer The instance.
* @param {ASTNode} node The current AST node.
* @returns {void}
*/
function leaveFromCurrentSegment(analyzer, node) {
const state = CodePath.getState(analyzer.codePath);
const currentSegments = state.currentSegments;
for (let i = 0; i < currentSegments.length; ++i) {
const currentSegment = currentSegments[i];
debug.dump(`onCodePathSegmentEnd ${currentSegment.id}`);
if (currentSegment.reachable) {
analyzer.emitter.emit(
"onCodePathSegmentEnd",
currentSegment,
node
);
}
}
state.currentSegments = [];
}
/**
* Updates the code path due to the position of a given node in the parent node
* thereof.
*
* For example, if the node is `parent.consequent`, this creates a fork from the
* current path.
* @param {CodePathAnalyzer} analyzer The instance.
* @param {ASTNode} node The current AST node.
* @returns {void}
*/
function preprocess(analyzer, node) {
const codePath = analyzer.codePath;
const state = CodePath.getState(codePath);
const parent = node.parent;
switch (parent.type) {
// The `arguments.length == 0` case is in `postprocess` function.
case "CallExpression":
if (parent.optional === true && parent.arguments.length >= 1 && parent.arguments[0] === node) {
state.makeOptionalRight();
}
break;
case "MemberExpression":
if (parent.optional === true && parent.property === node) {
state.makeOptionalRight();
}
break;
case "LogicalExpression":
if (
parent.right === node &&
isHandledLogicalOperator(parent.operator)
) {
state.makeLogicalRight();
}
break;
case "AssignmentExpression":
if (
parent.right === node &&
isLogicalAssignmentOperator(parent.operator)
) {
state.makeLogicalRight();
}
break;
case "ConditionalExpression":
case "IfStatement":
/*
* Fork if this node is at `consequent`/`alternate`.
* `popForkContext()` exists at `IfStatement:exit` and
* `ConditionalExpression:exit`.
*/
if (parent.consequent === node) {
state.makeIfConsequent();
} else if (parent.alternate === node) {
state.makeIfAlternate();
}
break;
case "SwitchCase":
if (parent.consequent[0] === node) {
state.makeSwitchCaseBody(false, !parent.test);
}
break;
case "TryStatement":
if (parent.handler === node) {
state.makeCatchBlock();
} else if (parent.finalizer === node) {
state.makeFinallyBlock();
}
break;
case "WhileStatement":
if (parent.test === node) {
state.makeWhileTest(getBooleanValueIfSimpleConstant(node));
} else {
assert(parent.body === node);
state.makeWhileBody();
}
break;
case "DoWhileStatement":
if (parent.body === node) {
state.makeDoWhileBody();
} else {
assert(parent.test === node);
state.makeDoWhileTest(getBooleanValueIfSimpleConstant(node));
}
break;
case "ForStatement":
if (parent.test === node) {
state.makeForTest(getBooleanValueIfSimpleConstant(node));
} else if (parent.update === node) {
state.makeForUpdate();
} else if (parent.body === node) {
state.makeForBody();
}
break;
case "ForInStatement":
case "ForOfStatement":
if (parent.left === node) {
state.makeForInOfLeft();
} else if (parent.right === node) {
state.makeForInOfRight();
} else {
assert(parent.body === node);
state.makeForInOfBody();
}
break;
case "AssignmentPattern":
/*
* Fork if this node is at `right`.
* `left` is executed always, so it uses the current path.
* `popForkContext()` exists at `AssignmentPattern:exit`.
*/
if (parent.right === node) {
state.pushForkContext();
state.forkBypassPath();
state.forkPath();
}
break;
default:
break;
}
}
/**
* Updates the code path due to the type of a given node in entering.
* @param {CodePathAnalyzer} analyzer The instance.
* @param {ASTNode} node The current AST node.
* @returns {void}
*/
function processCodePathToEnter(analyzer, node) {
let codePath = analyzer.codePath;
let state = codePath && CodePath.getState(codePath);
const parent = node.parent;
/**
* Creates a new code path and trigger the onCodePathStart event
* based on the currently selected node.
* @param {string} origin The reason the code path was started.
* @returns {void}
*/
function startCodePath(origin) {
if (codePath) {
// Emits onCodePathSegmentStart events if updated.
forwardCurrentToHead(analyzer, node);
debug.dumpState(node, state, false);
}
// Create the code path of this scope.
codePath = analyzer.codePath = new CodePath({
id: analyzer.idGenerator.next(),
origin,
upper: codePath,
onLooped: analyzer.onLooped
});
state = CodePath.getState(codePath);
// Emits onCodePathStart events.
debug.dump(`onCodePathStart ${codePath.id}`);
analyzer.emitter.emit("onCodePathStart", codePath, node);
}
/*
* Special case: The right side of class field initializer is considered
* to be its own function, so we need to start a new code path in this
* case.
*/
if (isPropertyDefinitionValue(node)) {
startCodePath("class-field-initializer");
/*
* Intentional fall through because `node` needs to also be
* processed by the code below. For example, if we have:
*
* class Foo {
* a = () => {}
* }
*
* In this case, we also need start a second code path.
*/
}
switch (node.type) {
case "Program":
startCodePath("program");
break;
case "FunctionDeclaration":
case "FunctionExpression":
case "ArrowFunctionExpression":
startCodePath("function");
break;
case "StaticBlock":
startCodePath("class-static-block");
break;
case "ChainExpression":
state.pushChainContext();
break;
case "CallExpression":
if (node.optional === true) {
state.makeOptionalNode();
}
break;
case "MemberExpression":
if (node.optional === true) {
state.makeOptionalNode();
}
break;
case "LogicalExpression":
if (isHandledLogicalOperator(node.operator)) {
state.pushChoiceContext(
node.operator,
isForkingByTrueOrFalse(node)
);
}
break;
case "AssignmentExpression":
if (isLogicalAssignmentOperator(node.operator)) {
state.pushChoiceContext(
node.operator.slice(0, -1), // removes `=` from the end
isForkingByTrueOrFalse(node)
);
}
break;
case "ConditionalExpression":
case "IfStatement":
state.pushChoiceContext("test", false);
break;
case "SwitchStatement":
state.pushSwitchContext(
node.cases.some(isCaseNode),
getLabel(node)
);
break;
case "TryStatement":
state.pushTryContext(Boolean(node.finalizer));
break;
case "SwitchCase":
/*
* Fork if this node is after the 2st node in `cases`.
* It's similar to `else` blocks.
* The next `test` node is processed in this path.
*/
if (parent.discriminant !== node && parent.cases[0] !== node) {
state.forkPath();
}
break;
case "WhileStatement":
case "DoWhileStatement":
case "ForStatement":
case "ForInStatement":
case "ForOfStatement":
state.pushLoopContext(node.type, getLabel(node));
break;
case "LabeledStatement":
if (!breakableTypePattern.test(node.body.type)) {
state.pushBreakContext(false, node.label.name);
}
break;
default:
break;
}
// Emits onCodePathSegmentStart events if updated.
forwardCurrentToHead(analyzer, node);
debug.dumpState(node, state, false);
}
/**
* Updates the code path due to the type of a given node in leaving.
* @param {CodePathAnalyzer} analyzer The instance.
* @param {ASTNode} node The current AST node.
* @returns {void}
*/
function processCodePathToExit(analyzer, node) {
const codePath = analyzer.codePath;
const state = CodePath.getState(codePath);
let dontForward = false;
switch (node.type) {
case "ChainExpression":
state.popChainContext();
break;
case "IfStatement":
case "ConditionalExpression":
state.popChoiceContext();
break;
case "LogicalExpression":
if (isHandledLogicalOperator(node.operator)) {
state.popChoiceContext();
}
break;
case "AssignmentExpression":
if (isLogicalAssignmentOperator(node.operator)) {
state.popChoiceContext();
}
break;
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;
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