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Diffstat (limited to 'tools/node_modules/eslint/lib/code-path-analysis/code-path-analyzer.js')
| -rw-r--r-- | tools/node_modules/eslint/lib/code-path-analysis/code-path-analyzer.js | 659 |
1 files changed, 659 insertions, 0 deletions
diff --git a/tools/node_modules/eslint/lib/code-path-analysis/code-path-analyzer.js b/tools/node_modules/eslint/lib/code-path-analysis/code-path-analyzer.js new file mode 100644 index 0000000000..1a4f7870ba --- /dev/null +++ b/tools/node_modules/eslint/lib/code-path-analysis/code-path-analyzer.js @@ -0,0 +1,659 @@ +/** + * @fileoverview A class of the code path analyzer. + * @author Toru Nagashima + */ + +"use strict"; + +//------------------------------------------------------------------------------ +// Requirements +//------------------------------------------------------------------------------ + +const assert = require("assert"), + CodePath = require("./code-path"), + CodePathSegment = require("./code-path-segment"), + IdGenerator = require("./id-generator"), + debug = require("./debug-helpers"), + astUtils = require("../ast-utils"); + +//------------------------------------------------------------------------------ +// 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 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 true; + + 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 "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) { + case "LogicalExpression": + if (parent.right === node) { + 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; + + switch (node.type) { + case "Program": + case "FunctionDeclaration": + case "FunctionExpression": + case "ArrowFunctionExpression": + 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( + analyzer.idGenerator.next(), + codePath, + analyzer.onLooped + ); + state = CodePath.getState(codePath); + + // Emits onCodePathStart events. + debug.dump(`onCodePathStart ${codePath.id}`); + analyzer.emitter.emit("onCodePathStart", codePath, node); + break; + + case "LogicalExpression": + state.pushChoiceContext(node.operator, isForkingByTrueOrFalse(node)); + break; + + case "ConditionalExpression": + case "IfStatement": + state.pushChoiceContext("test", false); + break; + + case "SwitchStatement": + state.pushSwitchContext( + node.cases.some(isCaseNode), + astUtils.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, astUtils.getLabel(node)); + break; + + case "LabeledStatement": + if (!astUtils.isBreakableStatement(node.body)) { + 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 "IfStatement": + case "ConditionalExpression": + case "LogicalExpression": + 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 "MemberExpression": + case "NewExpression": + state.makeFirstThrowablePathInTryBlock(); + break; + + case "WhileStatement": + case "DoWhileStatement": + case "ForStatement": + case "ForInStatement": + case "ForOfStatement": + state.popLoopContext(); + break; + + case "AssignmentPattern": + state.popForkContext(); + break; + + case "LabeledStatement": + if (!astUtils.isBreakableStatement(node.body)) { + 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) { + switch (node.type) { + case "Program": + case "FunctionDeclaration": + case "FunctionExpression": + case "ArrowFunctionExpression": { + 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); + } + break; + } + + default: + break; + } +} + +//------------------------------------------------------------------------------ +// 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; |