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Diffstat (limited to 'tools/node_modules/eslint/lib/code-path-analysis')
7 files changed, 3086 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; diff --git a/tools/node_modules/eslint/lib/code-path-analysis/code-path-segment.js b/tools/node_modules/eslint/lib/code-path-analysis/code-path-segment.js new file mode 100644 index 0000000000..8145f92801 --- /dev/null +++ b/tools/node_modules/eslint/lib/code-path-analysis/code-path-segment.js @@ -0,0 +1,245 @@ +/** + * @fileoverview A class of the code path segment. + * @author Toru Nagashima + */ + +"use strict"; + +//------------------------------------------------------------------------------ +// Requirements +//------------------------------------------------------------------------------ + +const debug = require("./debug-helpers"); + +//------------------------------------------------------------------------------ +// Helpers +//------------------------------------------------------------------------------ + +/** + * Checks whether or not a given segment is reachable. + * + * @param {CodePathSegment} segment - A segment to check. + * @returns {boolean} `true` if the segment is reachable. + */ +function isReachable(segment) { + return segment.reachable; +} + +//------------------------------------------------------------------------------ +// Public Interface +//------------------------------------------------------------------------------ + +/** + * A code path segment. + */ +class CodePathSegment { + + /** + * @param {string} id - An identifier. + * @param {CodePathSegment[]} allPrevSegments - An array of the previous segments. + * This array includes unreachable segments. + * @param {boolean} reachable - A flag which shows this is reachable. + */ + constructor(id, allPrevSegments, reachable) { + + /** + * The identifier of this code path. + * Rules use it to store additional information of each rule. + * @type {string} + */ + this.id = id; + + /** + * An array of the next segments. + * @type {CodePathSegment[]} + */ + this.nextSegments = []; + + /** + * An array of the previous segments. + * @type {CodePathSegment[]} + */ + this.prevSegments = allPrevSegments.filter(isReachable); + + /** + * An array of the next segments. + * This array includes unreachable segments. + * @type {CodePathSegment[]} + */ + this.allNextSegments = []; + + /** + * An array of the previous segments. + * This array includes unreachable segments. + * @type {CodePathSegment[]} + */ + this.allPrevSegments = allPrevSegments; + + /** + * A flag which shows this is reachable. + * @type {boolean} + */ + this.reachable = reachable; + + // Internal data. + Object.defineProperty(this, "internal", { + value: { + used: false, + loopedPrevSegments: [] + } + }); + + /* istanbul ignore if */ + if (debug.enabled) { + this.internal.nodes = []; + this.internal.exitNodes = []; + } + } + + /** + * Checks a given previous segment is coming from the end of a loop. + * + * @param {CodePathSegment} segment - A previous segment to check. + * @returns {boolean} `true` if the segment is coming from the end of a loop. + */ + isLoopedPrevSegment(segment) { + return this.internal.loopedPrevSegments.indexOf(segment) !== -1; + } + + /** + * Creates the root segment. + * + * @param {string} id - An identifier. + * @returns {CodePathSegment} The created segment. + */ + static newRoot(id) { + return new CodePathSegment(id, [], true); + } + + /** + * Creates a segment that follows given segments. + * + * @param {string} id - An identifier. + * @param {CodePathSegment[]} allPrevSegments - An array of the previous segments. + * @returns {CodePathSegment} The created segment. + */ + static newNext(id, allPrevSegments) { + return new CodePathSegment( + id, + CodePathSegment.flattenUnusedSegments(allPrevSegments), + allPrevSegments.some(isReachable) + ); + } + + /** + * Creates an unreachable segment that follows given segments. + * + * @param {string} id - An identifier. + * @param {CodePathSegment[]} allPrevSegments - An array of the previous segments. + * @returns {CodePathSegment} The created segment. + */ + static newUnreachable(id, allPrevSegments) { + const segment = new CodePathSegment(id, CodePathSegment.flattenUnusedSegments(allPrevSegments), false); + + /* + * In `if (a) return a; foo();` case, the unreachable segment preceded by + * the return statement is not used but must not be remove. + */ + CodePathSegment.markUsed(segment); + + return segment; + } + + /** + * Creates a segment that follows given segments. + * This factory method does not connect with `allPrevSegments`. + * But this inherits `reachable` flag. + * + * @param {string} id - An identifier. + * @param {CodePathSegment[]} allPrevSegments - An array of the previous segments. + * @returns {CodePathSegment} The created segment. + */ + static newDisconnected(id, allPrevSegments) { + return new CodePathSegment(id, [], allPrevSegments.some(isReachable)); + } + + /** + * Makes a given segment being used. + * + * And this function registers the segment into the previous segments as a next. + * + * @param {CodePathSegment} segment - A segment to mark. + * @returns {void} + */ + static markUsed(segment) { + if (segment.internal.used) { + return; + } + segment.internal.used = true; + + let i; + + if (segment.reachable) { + for (i = 0; i < segment.allPrevSegments.length; ++i) { + const prevSegment = segment.allPrevSegments[i]; + + prevSegment.allNextSegments.push(segment); + prevSegment.nextSegments.push(segment); + } + } else { + for (i = 0; i < segment.allPrevSegments.length; ++i) { + segment.allPrevSegments[i].allNextSegments.push(segment); + } + } + } + + /** + * Marks a previous segment as looped. + * + * @param {CodePathSegment} segment - A segment. + * @param {CodePathSegment} prevSegment - A previous segment to mark. + * @returns {void} + */ + static markPrevSegmentAsLooped(segment, prevSegment) { + segment.internal.loopedPrevSegments.push(prevSegment); + } + + /** + * Replaces unused segments with the previous segments of each unused segment. + * + * @param {CodePathSegment[]} segments - An array of segments to replace. + * @returns {CodePathSegment[]} The replaced array. + */ + static flattenUnusedSegments(segments) { + const done = Object.create(null); + const retv = []; + + for (let i = 0; i < segments.length; ++i) { + const segment = segments[i]; + + // Ignores duplicated. + if (done[segment.id]) { + continue; + } + + // Use previous segments if unused. + if (!segment.internal.used) { + for (let j = 0; j < segment.allPrevSegments.length; ++j) { + const prevSegment = segment.allPrevSegments[j]; + + if (!done[prevSegment.id]) { + done[prevSegment.id] = true; + retv.push(prevSegment); + } + } + } else { + done[segment.id] = true; + retv.push(segment); + } + } + + return retv; + } +} + +module.exports = CodePathSegment; diff --git a/tools/node_modules/eslint/lib/code-path-analysis/code-path-state.js b/tools/node_modules/eslint/lib/code-path-analysis/code-path-state.js new file mode 100644 index 0000000000..0c31e2072b --- /dev/null +++ b/tools/node_modules/eslint/lib/code-path-analysis/code-path-state.js @@ -0,0 +1,1440 @@ +/** + * @fileoverview A class to manage state of generating a code path. + * @author Toru Nagashima + */ + +"use strict"; + +//------------------------------------------------------------------------------ +// Requirements +//------------------------------------------------------------------------------ + +const CodePathSegment = require("./code-path-segment"), + ForkContext = require("./fork-context"); + +//------------------------------------------------------------------------------ +// Helpers +//------------------------------------------------------------------------------ + +/** + * Adds given segments into the `dest` array. + * If the `others` array does not includes the given segments, adds to the `all` + * array as well. + * + * This adds only reachable and used segments. + * + * @param {CodePathSegment[]} dest - A destination array (`returnedSegments` or `thrownSegments`). + * @param {CodePathSegment[]} others - Another destination array (`returnedSegments` or `thrownSegments`). + * @param {CodePathSegment[]} all - The unified destination array (`finalSegments`). + * @param {CodePathSegment[]} segments - Segments to add. + * @returns {void} + */ +function addToReturnedOrThrown(dest, others, all, segments) { + for (let i = 0; i < segments.length; ++i) { + const segment = segments[i]; + + dest.push(segment); + if (others.indexOf(segment) === -1) { + all.push(segment); + } + } +} + +/** + * Gets a loop-context for a `continue` statement. + * + * @param {CodePathState} state - A state to get. + * @param {string} label - The label of a `continue` statement. + * @returns {LoopContext} A loop-context for a `continue` statement. + */ +function getContinueContext(state, label) { + if (!label) { + return state.loopContext; + } + + let context = state.loopContext; + + while (context) { + if (context.label === label) { + return context; + } + context = context.upper; + } + + /* istanbul ignore next: foolproof (syntax error) */ + return null; +} + +/** + * Gets a context for a `break` statement. + * + * @param {CodePathState} state - A state to get. + * @param {string} label - The label of a `break` statement. + * @returns {LoopContext|SwitchContext} A context for a `break` statement. + */ +function getBreakContext(state, label) { + let context = state.breakContext; + + while (context) { + if (label ? context.label === label : context.breakable) { + return context; + } + context = context.upper; + } + + /* istanbul ignore next: foolproof (syntax error) */ + return null; +} + +/** + * Gets a context for a `return` statement. + * + * @param {CodePathState} state - A state to get. + * @returns {TryContext|CodePathState} A context for a `return` statement. + */ +function getReturnContext(state) { + let context = state.tryContext; + + while (context) { + if (context.hasFinalizer && context.position !== "finally") { + return context; + } + context = context.upper; + } + + return state; +} + +/** + * Gets a context for a `throw` statement. + * + * @param {CodePathState} state - A state to get. + * @returns {TryContext|CodePathState} A context for a `throw` statement. + */ +function getThrowContext(state) { + let context = state.tryContext; + + while (context) { + if (context.position === "try" || + (context.hasFinalizer && context.position === "catch") + ) { + return context; + } + context = context.upper; + } + + return state; +} + +/** + * Removes a given element from a given array. + * + * @param {any[]} xs - An array to remove the specific element. + * @param {any} x - An element to be removed. + * @returns {void} + */ +function remove(xs, x) { + xs.splice(xs.indexOf(x), 1); +} + +/** + * Disconnect given segments. + * + * This is used in a process for switch statements. + * If there is the "default" chunk before other cases, the order is different + * between node's and running's. + * + * @param {CodePathSegment[]} prevSegments - Forward segments to disconnect. + * @param {CodePathSegment[]} nextSegments - Backward segments to disconnect. + * @returns {void} + */ +function removeConnection(prevSegments, nextSegments) { + for (let i = 0; i < prevSegments.length; ++i) { + const prevSegment = prevSegments[i]; + const nextSegment = nextSegments[i]; + + remove(prevSegment.nextSegments, nextSegment); + remove(prevSegment.allNextSegments, nextSegment); + remove(nextSegment.prevSegments, prevSegment); + remove(nextSegment.allPrevSegments, prevSegment); + } +} + +/** + * Creates looping path. + * + * @param {CodePathState} state - The instance. + * @param {CodePathSegment[]} fromSegments - Segments which are source. + * @param {CodePathSegment[]} toSegments - Segments which are destination. + * @returns {void} + */ +function makeLooped(state, fromSegments, toSegments) { + fromSegments = CodePathSegment.flattenUnusedSegments(fromSegments); + toSegments = CodePathSegment.flattenUnusedSegments(toSegments); + + const end = Math.min(fromSegments.length, toSegments.length); + + for (let i = 0; i < end; ++i) { + const fromSegment = fromSegments[i]; + const toSegment = toSegments[i]; + + if (toSegment.reachable) { + fromSegment.nextSegments.push(toSegment); + } + if (fromSegment.reachable) { + toSegment.prevSegments.push(fromSegment); + } + fromSegment.allNextSegments.push(toSegment); + toSegment.allPrevSegments.push(fromSegment); + + if (toSegment.allPrevSegments.length >= 2) { + CodePathSegment.markPrevSegmentAsLooped(toSegment, fromSegment); + } + + state.notifyLooped(fromSegment, toSegment); + } +} + +/** + * Finalizes segments of `test` chunk of a ForStatement. + * + * - Adds `false` paths to paths which are leaving from the loop. + * - Sets `true` paths to paths which go to the body. + * + * @param {LoopContext} context - A loop context to modify. + * @param {ChoiceContext} choiceContext - A choice context of this loop. + * @param {CodePathSegment[]} head - The current head paths. + * @returns {void} + */ +function finalizeTestSegmentsOfFor(context, choiceContext, head) { + if (!choiceContext.processed) { + choiceContext.trueForkContext.add(head); + choiceContext.falseForkContext.add(head); + } + + if (context.test !== true) { + context.brokenForkContext.addAll(choiceContext.falseForkContext); + } + context.endOfTestSegments = choiceContext.trueForkContext.makeNext(0, -1); +} + +//------------------------------------------------------------------------------ +// Public Interface +//------------------------------------------------------------------------------ + +/** + * A class which manages state to analyze code paths. + */ +class CodePathState { + + /** + * @param {IdGenerator} idGenerator - An id generator to generate id for code + * path segments. + * @param {Function} onLooped - A callback function to notify looping. + */ + constructor(idGenerator, onLooped) { + this.idGenerator = idGenerator; + this.notifyLooped = onLooped; + this.forkContext = ForkContext.newRoot(idGenerator); + this.choiceContext = null; + this.switchContext = null; + this.tryContext = null; + this.loopContext = null; + this.breakContext = null; + + this.currentSegments = []; + this.initialSegment = this.forkContext.head[0]; + + // returnedSegments and thrownSegments push elements into finalSegments also. + const final = this.finalSegments = []; + const returned = this.returnedForkContext = []; + const thrown = this.thrownForkContext = []; + + returned.add = addToReturnedOrThrown.bind(null, returned, thrown, final); + thrown.add = addToReturnedOrThrown.bind(null, thrown, returned, final); + } + + /** + * The head segments. + * @type {CodePathSegment[]} + */ + get headSegments() { + return this.forkContext.head; + } + + /** + * The parent forking context. + * This is used for the root of new forks. + * @type {ForkContext} + */ + get parentForkContext() { + const current = this.forkContext; + + return current && current.upper; + } + + /** + * Creates and stacks new forking context. + * + * @param {boolean} forkLeavingPath - A flag which shows being in a + * "finally" block. + * @returns {ForkContext} The created context. + */ + pushForkContext(forkLeavingPath) { + this.forkContext = ForkContext.newEmpty( + this.forkContext, + forkLeavingPath + ); + + return this.forkContext; + } + + /** + * Pops and merges the last forking context. + * @returns {ForkContext} The last context. + */ + popForkContext() { + const lastContext = this.forkContext; + + this.forkContext = lastContext.upper; + this.forkContext.replaceHead(lastContext.makeNext(0, -1)); + + return lastContext; + } + + /** + * Creates a new path. + * @returns {void} + */ + forkPath() { + this.forkContext.add(this.parentForkContext.makeNext(-1, -1)); + } + + /** + * Creates a bypass path. + * This is used for such as IfStatement which does not have "else" chunk. + * + * @returns {void} + */ + forkBypassPath() { + this.forkContext.add(this.parentForkContext.head); + } + + //-------------------------------------------------------------------------- + // ConditionalExpression, LogicalExpression, IfStatement + //-------------------------------------------------------------------------- + + /** + * Creates a context for ConditionalExpression, LogicalExpression, + * IfStatement, WhileStatement, DoWhileStatement, or ForStatement. + * + * LogicalExpressions have cases that it goes different paths between the + * `true` case and the `false` case. + * + * For Example: + * + * if (a || b) { + * foo(); + * } else { + * bar(); + * } + * + * In this case, `b` is evaluated always in the code path of the `else` + * block, but it's not so in the code path of the `if` block. + * So there are 3 paths. + * + * a -> foo(); + * a -> b -> foo(); + * a -> b -> bar(); + * + * @param {string} kind - A kind string. + * If the new context is LogicalExpression's, this is `"&&"` or `"||"`. + * If it's IfStatement's or ConditionalExpression's, this is `"test"`. + * Otherwise, this is `"loop"`. + * @param {boolean} isForkingAsResult - A flag that shows that goes different + * paths between `true` and `false`. + * @returns {void} + */ + pushChoiceContext(kind, isForkingAsResult) { + this.choiceContext = { + upper: this.choiceContext, + kind, + isForkingAsResult, + trueForkContext: ForkContext.newEmpty(this.forkContext), + falseForkContext: ForkContext.newEmpty(this.forkContext), + processed: false + }; + } + + /** + * Pops the last choice context and finalizes it. + * + * @returns {ChoiceContext} The popped context. + */ + popChoiceContext() { + const context = this.choiceContext; + + this.choiceContext = context.upper; + + const forkContext = this.forkContext; + const headSegments = forkContext.head; + + switch (context.kind) { + case "&&": + case "||": + + /* + * If any result were not transferred from child contexts, + * this sets the head segments to both cases. + * The head segments are the path of the right-hand operand. + */ + if (!context.processed) { + context.trueForkContext.add(headSegments); + context.falseForkContext.add(headSegments); + } + + /* + * Transfers results to upper context if this context is in + * test chunk. + */ + if (context.isForkingAsResult) { + const parentContext = this.choiceContext; + + parentContext.trueForkContext.addAll(context.trueForkContext); + parentContext.falseForkContext.addAll(context.falseForkContext); + parentContext.processed = true; + + return context; + } + + break; + + case "test": + if (!context.processed) { + + /* + * The head segments are the path of the `if` block here. + * Updates the `true` path with the end of the `if` block. + */ + context.trueForkContext.clear(); + context.trueForkContext.add(headSegments); + } else { + + /* + * The head segments are the path of the `else` block here. + * Updates the `false` path with the end of the `else` + * block. + */ + context.falseForkContext.clear(); + context.falseForkContext.add(headSegments); + } + + break; + + case "loop": + + /* + * Loops are addressed in popLoopContext(). + * This is called from popLoopContext(). + */ + return context; + + /* istanbul ignore next */ + default: + throw new Error("unreachable"); + } + + // Merges all paths. + const prevForkContext = context.trueForkContext; + + prevForkContext.addAll(context.falseForkContext); + forkContext.replaceHead(prevForkContext.makeNext(0, -1)); + + return context; + } + + /** + * Makes a code path segment of the right-hand operand of a logical + * expression. + * + * @returns {void} + */ + makeLogicalRight() { + const context = this.choiceContext; + const forkContext = this.forkContext; + + if (context.processed) { + + /* + * This got segments already from the child choice context. + * Creates the next path from own true/false fork context. + */ + const prevForkContext = + context.kind === "&&" ? context.trueForkContext + /* kind === "||" */ : context.falseForkContext; + + forkContext.replaceHead(prevForkContext.makeNext(0, -1)); + prevForkContext.clear(); + + context.processed = false; + } else { + + /* + * This did not get segments from the child choice context. + * So addresses the head segments. + * The head segments are the path of the left-hand operand. + */ + if (context.kind === "&&") { + + // The path does short-circuit if false. + context.falseForkContext.add(forkContext.head); + } else { + + // The path does short-circuit if true. + context.trueForkContext.add(forkContext.head); + } + + forkContext.replaceHead(forkContext.makeNext(-1, -1)); + } + } + + /** + * Makes a code path segment of the `if` block. + * + * @returns {void} + */ + makeIfConsequent() { + const context = this.choiceContext; + const forkContext = this.forkContext; + + /* + * If any result were not transferred from child contexts, + * this sets the head segments to both cases. + * The head segments are the path of the test expression. + */ + if (!context.processed) { + context.trueForkContext.add(forkContext.head); + context.falseForkContext.add(forkContext.head); + } + + context.processed = false; + + // Creates new path from the `true` case. + forkContext.replaceHead( + context.trueForkContext.makeNext(0, -1) + ); + } + + /** + * Makes a code path segment of the `else` block. + * + * @returns {void} + */ + makeIfAlternate() { + const context = this.choiceContext; + const forkContext = this.forkContext; + + /* + * The head segments are the path of the `if` block. + * Updates the `true` path with the end of the `if` block. + */ + context.trueForkContext.clear(); + context.trueForkContext.add(forkContext.head); + context.processed = true; + + // Creates new path from the `false` case. + forkContext.replaceHead( + context.falseForkContext.makeNext(0, -1) + ); + } + + //-------------------------------------------------------------------------- + // SwitchStatement + //-------------------------------------------------------------------------- + + /** + * Creates a context object of SwitchStatement and stacks it. + * + * @param {boolean} hasCase - `true` if the switch statement has one or more + * case parts. + * @param {string|null} label - The label text. + * @returns {void} + */ + pushSwitchContext(hasCase, label) { + this.switchContext = { + upper: this.switchContext, + hasCase, + defaultSegments: null, + defaultBodySegments: null, + foundDefault: false, + lastIsDefault: false, + countForks: 0 + }; + + this.pushBreakContext(true, label); + } + + /** + * Pops the last context of SwitchStatement and finalizes it. + * + * - Disposes all forking stack for `case` and `default`. + * - Creates the next code path segment from `context.brokenForkContext`. + * - If the last `SwitchCase` node is not a `default` part, creates a path + * to the `default` body. + * + * @returns {void} + */ + popSwitchContext() { + const context = this.switchContext; + + this.switchContext = context.upper; + + const forkContext = this.forkContext; + const brokenForkContext = this.popBreakContext().brokenForkContext; + + if (context.countForks === 0) { + + /* + * When there is only one `default` chunk and there is one or more + * `break` statements, even if forks are nothing, it needs to merge + * those. + */ + if (!brokenForkContext.empty) { + brokenForkContext.add(forkContext.makeNext(-1, -1)); + forkContext.replaceHead(brokenForkContext.makeNext(0, -1)); + } + + return; + } + + const lastSegments = forkContext.head; + + this.forkBypassPath(); + const lastCaseSegments = forkContext.head; + + /* + * `brokenForkContext` is used to make the next segment. + * It must add the last segment into `brokenForkContext`. + */ + brokenForkContext.add(lastSegments); + + /* + * A path which is failed in all case test should be connected to path + * of `default` chunk. + */ + if (!context.lastIsDefault) { + if (context.defaultBodySegments) { + + /* + * Remove a link from `default` label to its chunk. + * It's false route. + */ + removeConnection(context.defaultSegments, context.defaultBodySegments); + makeLooped(this, lastCaseSegments, context.defaultBodySegments); + } else { + + /* + * It handles the last case body as broken if `default` chunk + * does not exist. + */ + brokenForkContext.add(lastCaseSegments); + } + } + + // Pops the segment context stack until the entry segment. + for (let i = 0; i < context.countForks; ++i) { + this.forkContext = this.forkContext.upper; + } + + /* + * Creates a path from all brokenForkContext paths. + * This is a path after switch statement. + */ + this.forkContext.replaceHead(brokenForkContext.makeNext(0, -1)); + } + + /** + * Makes a code path segment for a `SwitchCase` node. + * + * @param {boolean} isEmpty - `true` if the body is empty. + * @param {boolean} isDefault - `true` if the body is the default case. + * @returns {void} + */ + makeSwitchCaseBody(isEmpty, isDefault) { + const context = this.switchContext; + + if (!context.hasCase) { + return; + } + + /* + * Merge forks. + * The parent fork context has two segments. + * Those are from the current case and the body of the previous case. + */ + const parentForkContext = this.forkContext; + const forkContext = this.pushForkContext(); + + forkContext.add(parentForkContext.makeNext(0, -1)); + + /* + * Save `default` chunk info. + * If the `default` label is not at the last, we must make a path from + * the last `case` to the `default` chunk. + */ + if (isDefault) { + context.defaultSegments = parentForkContext.head; + if (isEmpty) { + context.foundDefault = true; + } else { + context.defaultBodySegments = forkContext.head; + } + } else { + if (!isEmpty && context.foundDefault) { + context.foundDefault = false; + context.defaultBodySegments = forkContext.head; + } + } + + context.lastIsDefault = isDefault; + context.countForks += 1; + } + + //-------------------------------------------------------------------------- + // TryStatement + //-------------------------------------------------------------------------- + + /** + * Creates a context object of TryStatement and stacks it. + * + * @param {boolean} hasFinalizer - `true` if the try statement has a + * `finally` block. + * @returns {void} + */ + pushTryContext(hasFinalizer) { + this.tryContext = { + upper: this.tryContext, + position: "try", + hasFinalizer, + + returnedForkContext: hasFinalizer + ? ForkContext.newEmpty(this.forkContext) + : null, + + thrownForkContext: ForkContext.newEmpty(this.forkContext), + lastOfTryIsReachable: false, + lastOfCatchIsReachable: false + }; + } + + /** + * Pops the last context of TryStatement and finalizes it. + * + * @returns {void} + */ + popTryContext() { + const context = this.tryContext; + + this.tryContext = context.upper; + + if (context.position === "catch") { + + // Merges two paths from the `try` block and `catch` block merely. + this.popForkContext(); + return; + } + + /* + * The following process is executed only when there is the `finally` + * block. + */ + + const returned = context.returnedForkContext; + const thrown = context.thrownForkContext; + + if (returned.empty && thrown.empty) { + return; + } + + // Separate head to normal paths and leaving paths. + const headSegments = this.forkContext.head; + + this.forkContext = this.forkContext.upper; + const normalSegments = headSegments.slice(0, headSegments.length / 2 | 0); + const leavingSegments = headSegments.slice(headSegments.length / 2 | 0); + + // Forwards the leaving path to upper contexts. + if (!returned.empty) { + getReturnContext(this).returnedForkContext.add(leavingSegments); + } + if (!thrown.empty) { + getThrowContext(this).thrownForkContext.add(leavingSegments); + } + + // Sets the normal path as the next. + this.forkContext.replaceHead(normalSegments); + + /* + * If both paths of the `try` block and the `catch` block are + * unreachable, the next path becomes unreachable as well. + */ + if (!context.lastOfTryIsReachable && !context.lastOfCatchIsReachable) { + this.forkContext.makeUnreachable(); + } + } + + /** + * Makes a code path segment for a `catch` block. + * + * @returns {void} + */ + makeCatchBlock() { + const context = this.tryContext; + const forkContext = this.forkContext; + const thrown = context.thrownForkContext; + + // Update state. + context.position = "catch"; + context.thrownForkContext = ForkContext.newEmpty(forkContext); + context.lastOfTryIsReachable = forkContext.reachable; + + // Merge thrown paths. + thrown.add(forkContext.head); + const thrownSegments = thrown.makeNext(0, -1); + + // Fork to a bypass and the merged thrown path. + this.pushForkContext(); + this.forkBypassPath(); + this.forkContext.add(thrownSegments); + } + + /** + * Makes a code path segment for a `finally` block. + * + * In the `finally` block, parallel paths are created. The parallel paths + * are used as leaving-paths. The leaving-paths are paths from `return` + * statements and `throw` statements in a `try` block or a `catch` block. + * + * @returns {void} + */ + makeFinallyBlock() { + const context = this.tryContext; + let forkContext = this.forkContext; + const returned = context.returnedForkContext; + const thrown = context.thrownForkContext; + const headOfLeavingSegments = forkContext.head; + + // Update state. + if (context.position === "catch") { + + // Merges two paths from the `try` block and `catch` block. + this.popForkContext(); + forkContext = this.forkContext; + + context.lastOfCatchIsReachable = forkContext.reachable; + } else { + context.lastOfTryIsReachable = forkContext.reachable; + } + context.position = "finally"; + + if (returned.empty && thrown.empty) { + + // This path does not leave. + return; + } + + /* + * Create a parallel segment from merging returned and thrown. + * This segment will leave at the end of this finally block. + */ + const segments = forkContext.makeNext(-1, -1); + + for (let i = 0; i < forkContext.count; ++i) { + const prevSegsOfLeavingSegment = [headOfLeavingSegments[i]]; + + for (let j = 0; j < returned.segmentsList.length; ++j) { + prevSegsOfLeavingSegment.push(returned.segmentsList[j][i]); + } + for (let j = 0; j < thrown.segmentsList.length; ++j) { + prevSegsOfLeavingSegment.push(thrown.segmentsList[j][i]); + } + + segments.push( + CodePathSegment.newNext( + this.idGenerator.next(), + prevSegsOfLeavingSegment + ) + ); + } + + this.pushForkContext(true); + this.forkContext.add(segments); + } + + /** + * Makes a code path segment from the first throwable node to the `catch` + * block or the `finally` block. + * + * @returns {void} + */ + makeFirstThrowablePathInTryBlock() { + const forkContext = this.forkContext; + + if (!forkContext.reachable) { + return; + } + + const context = getThrowContext(this); + + if (context === this || + context.position !== "try" || + !context.thrownForkContext.empty + ) { + return; + } + + context.thrownForkContext.add(forkContext.head); + forkContext.replaceHead(forkContext.makeNext(-1, -1)); + } + + //-------------------------------------------------------------------------- + // Loop Statements + //-------------------------------------------------------------------------- + + /** + * Creates a context object of a loop statement and stacks it. + * + * @param {string} type - The type of the node which was triggered. One of + * `WhileStatement`, `DoWhileStatement`, `ForStatement`, `ForInStatement`, + * and `ForStatement`. + * @param {string|null} label - A label of the node which was triggered. + * @returns {void} + */ + pushLoopContext(type, label) { + const forkContext = this.forkContext; + const breakContext = this.pushBreakContext(true, label); + + switch (type) { + case "WhileStatement": + this.pushChoiceContext("loop", false); + this.loopContext = { + upper: this.loopContext, + type, + label, + test: void 0, + continueDestSegments: null, + brokenForkContext: breakContext.brokenForkContext + }; + break; + + case "DoWhileStatement": + this.pushChoiceContext("loop", false); + this.loopContext = { + upper: this.loopContext, + type, + label, + test: void 0, + entrySegments: null, + continueForkContext: ForkContext.newEmpty(forkContext), + brokenForkContext: breakContext.brokenForkContext + }; + break; + + case "ForStatement": + this.pushChoiceContext("loop", false); + this.loopContext = { + upper: this.loopContext, + type, + label, + test: void 0, + endOfInitSegments: null, + testSegments: null, + endOfTestSegments: null, + updateSegments: null, + endOfUpdateSegments: null, + continueDestSegments: null, + brokenForkContext: breakContext.brokenForkContext + }; + break; + + case "ForInStatement": + case "ForOfStatement": + this.loopContext = { + upper: this.loopContext, + type, + label, + prevSegments: null, + leftSegments: null, + endOfLeftSegments: null, + continueDestSegments: null, + brokenForkContext: breakContext.brokenForkContext + }; + break; + + /* istanbul ignore next */ + default: + throw new Error(`unknown type: "${type}"`); + } + } + + /** + * Pops the last context of a loop statement and finalizes it. + * + * @returns {void} + */ + popLoopContext() { + const context = this.loopContext; + + this.loopContext = context.upper; + + const forkContext = this.forkContext; + const brokenForkContext = this.popBreakContext().brokenForkContext; + + // Creates a looped path. + switch (context.type) { + case "WhileStatement": + case "ForStatement": + this.popChoiceContext(); + makeLooped( + this, + forkContext.head, + context.continueDestSegments + ); + break; + + case "DoWhileStatement": { + const choiceContext = this.popChoiceContext(); + + if (!choiceContext.processed) { + choiceContext.trueForkContext.add(forkContext.head); + choiceContext.falseForkContext.add(forkContext.head); + } + if (context.test !== true) { + brokenForkContext.addAll(choiceContext.falseForkContext); + } + + // `true` paths go to looping. + const segmentsList = choiceContext.trueForkContext.segmentsList; + + for (let i = 0; i < segmentsList.length; ++i) { + makeLooped( + this, + segmentsList[i], + context.entrySegments + ); + } + break; + } + + case "ForInStatement": + case "ForOfStatement": + brokenForkContext.add(forkContext.head); + makeLooped( + this, + forkContext.head, + context.leftSegments + ); + break; + + /* istanbul ignore next */ + default: + throw new Error("unreachable"); + } + + // Go next. + if (brokenForkContext.empty) { + forkContext.replaceHead(forkContext.makeUnreachable(-1, -1)); + } else { + forkContext.replaceHead(brokenForkContext.makeNext(0, -1)); + } + } + + /** + * Makes a code path segment for the test part of a WhileStatement. + * + * @param {boolean|undefined} test - The test value (only when constant). + * @returns {void} + */ + makeWhileTest(test) { + const context = this.loopContext; + const forkContext = this.forkContext; + const testSegments = forkContext.makeNext(0, -1); + + // Update state. + context.test = test; + context.continueDestSegments = testSegments; + forkContext.replaceHead(testSegments); + } + + /** + * Makes a code path segment for the body part of a WhileStatement. + * + * @returns {void} + */ + makeWhileBody() { + const context = this.loopContext; + const choiceContext = this.choiceContext; + const forkContext = this.forkContext; + + if (!choiceContext.processed) { + choiceContext.trueForkContext.add(forkContext.head); + choiceContext.falseForkContext.add(forkContext.head); + } + + // Update state. + if (context.test !== true) { + context.brokenForkContext.addAll(choiceContext.falseForkContext); + } + forkContext.replaceHead(choiceContext.trueForkContext.makeNext(0, -1)); + } + + /** + * Makes a code path segment for the body part of a DoWhileStatement. + * + * @returns {void} + */ + makeDoWhileBody() { + const context = this.loopContext; + const forkContext = this.forkContext; + const bodySegments = forkContext.makeNext(-1, -1); + + // Update state. + context.entrySegments = bodySegments; + forkContext.replaceHead(bodySegments); + } + + /** + * Makes a code path segment for the test part of a DoWhileStatement. + * + * @param {boolean|undefined} test - The test value (only when constant). + * @returns {void} + */ + makeDoWhileTest(test) { + const context = this.loopContext; + const forkContext = this.forkContext; + + context.test = test; + + // Creates paths of `continue` statements. + if (!context.continueForkContext.empty) { + context.continueForkContext.add(forkContext.head); + const testSegments = context.continueForkContext.makeNext(0, -1); + + forkContext.replaceHead(testSegments); + } + } + + /** + * Makes a code path segment for the test part of a ForStatement. + * + * @param {boolean|undefined} test - The test value (only when constant). + * @returns {void} + */ + makeForTest(test) { + const context = this.loopContext; + const forkContext = this.forkContext; + const endOfInitSegments = forkContext.head; + const testSegments = forkContext.makeNext(-1, -1); + + // Update state. + context.test = test; + context.endOfInitSegments = endOfInitSegments; + context.continueDestSegments = context.testSegments = testSegments; + forkContext.replaceHead(testSegments); + } + + /** + * Makes a code path segment for the update part of a ForStatement. + * + * @returns {void} + */ + makeForUpdate() { + const context = this.loopContext; + const choiceContext = this.choiceContext; + const forkContext = this.forkContext; + + // Make the next paths of the test. + if (context.testSegments) { + finalizeTestSegmentsOfFor( + context, + choiceContext, + forkContext.head + ); + } else { + context.endOfInitSegments = forkContext.head; + } + + // Update state. + const updateSegments = forkContext.makeDisconnected(-1, -1); + + context.continueDestSegments = context.updateSegments = updateSegments; + forkContext.replaceHead(updateSegments); + } + + /** + * Makes a code path segment for the body part of a ForStatement. + * + * @returns {void} + */ + makeForBody() { + const context = this.loopContext; + const choiceContext = this.choiceContext; + const forkContext = this.forkContext; + + // Update state. + if (context.updateSegments) { + context.endOfUpdateSegments = forkContext.head; + + // `update` -> `test` + if (context.testSegments) { + makeLooped( + this, + context.endOfUpdateSegments, + context.testSegments + ); + } + } else if (context.testSegments) { + finalizeTestSegmentsOfFor( + context, + choiceContext, + forkContext.head + ); + } else { + context.endOfInitSegments = forkContext.head; + } + + let bodySegments = context.endOfTestSegments; + + if (!bodySegments) { + + /* + * If there is not the `test` part, the `body` path comes from the + * `init` part and the `update` part. + */ + const prevForkContext = ForkContext.newEmpty(forkContext); + + prevForkContext.add(context.endOfInitSegments); + if (context.endOfUpdateSegments) { + prevForkContext.add(context.endOfUpdateSegments); + } + + bodySegments = prevForkContext.makeNext(0, -1); + } + context.continueDestSegments = context.continueDestSegments || bodySegments; + forkContext.replaceHead(bodySegments); + } + + /** + * Makes a code path segment for the left part of a ForInStatement and a + * ForOfStatement. + * + * @returns {void} + */ + makeForInOfLeft() { + const context = this.loopContext; + const forkContext = this.forkContext; + const leftSegments = forkContext.makeDisconnected(-1, -1); + + // Update state. + context.prevSegments = forkContext.head; + context.leftSegments = context.continueDestSegments = leftSegments; + forkContext.replaceHead(leftSegments); + } + + /** + * Makes a code path segment for the right part of a ForInStatement and a + * ForOfStatement. + * + * @returns {void} + */ + makeForInOfRight() { + const context = this.loopContext; + const forkContext = this.forkContext; + const temp = ForkContext.newEmpty(forkContext); + + temp.add(context.prevSegments); + const rightSegments = temp.makeNext(-1, -1); + + // Update state. + context.endOfLeftSegments = forkContext.head; + forkContext.replaceHead(rightSegments); + } + + /** + * Makes a code path segment for the body part of a ForInStatement and a + * ForOfStatement. + * + * @returns {void} + */ + makeForInOfBody() { + const context = this.loopContext; + const forkContext = this.forkContext; + const temp = ForkContext.newEmpty(forkContext); + + temp.add(context.endOfLeftSegments); + const bodySegments = temp.makeNext(-1, -1); + + // Make a path: `right` -> `left`. + makeLooped(this, forkContext.head, context.leftSegments); + + // Update state. + context.brokenForkContext.add(forkContext.head); + forkContext.replaceHead(bodySegments); + } + + //-------------------------------------------------------------------------- + // Control Statements + //-------------------------------------------------------------------------- + + /** + * Creates new context for BreakStatement. + * + * @param {boolean} breakable - The flag to indicate it can break by + * an unlabeled BreakStatement. + * @param {string|null} label - The label of this context. + * @returns {Object} The new context. + */ + pushBreakContext(breakable, label) { + this.breakContext = { + upper: this.breakContext, + breakable, + label, + brokenForkContext: ForkContext.newEmpty(this.forkContext) + }; + return this.breakContext; + } + + /** + * Removes the top item of the break context stack. + * + * @returns {Object} The removed context. + */ + popBreakContext() { + const context = this.breakContext; + const forkContext = this.forkContext; + + this.breakContext = context.upper; + + // Process this context here for other than switches and loops. + if (!context.breakable) { + const brokenForkContext = context.brokenForkContext; + + if (!brokenForkContext.empty) { + brokenForkContext.add(forkContext.head); + forkContext.replaceHead(brokenForkContext.makeNext(0, -1)); + } + } + + return context; + } + + /** + * Makes a path for a `break` statement. + * + * It registers the head segment to a context of `break`. + * It makes new unreachable segment, then it set the head with the segment. + * + * @param {string} label - A label of the break statement. + * @returns {void} + */ + makeBreak(label) { + const forkContext = this.forkContext; + + if (!forkContext.reachable) { + return; + } + + const context = getBreakContext(this, label); + + /* istanbul ignore else: foolproof (syntax error) */ + if (context) { + context.brokenForkContext.add(forkContext.head); + } + + forkContext.replaceHead(forkContext.makeUnreachable(-1, -1)); + } + + /** + * Makes a path for a `continue` statement. + * + * It makes a looping path. + * It makes new unreachable segment, then it set the head with the segment. + * + * @param {string} label - A label of the continue statement. + * @returns {void} + */ + makeContinue(label) { + const forkContext = this.forkContext; + + if (!forkContext.reachable) { + return; + } + + const context = getContinueContext(this, label); + + /* istanbul ignore else: foolproof (syntax error) */ + if (context) { + if (context.continueDestSegments) { + makeLooped(this, forkContext.head, context.continueDestSegments); + + // If the context is a for-in/of loop, this effects a break also. + if (context.type === "ForInStatement" || + context.type === "ForOfStatement" + ) { + context.brokenForkContext.add(forkContext.head); + } + } else { + context.continueForkContext.add(forkContext.head); + } + } + forkContext.replaceHead(forkContext.makeUnreachable(-1, -1)); + } + + /** + * Makes a path for a `return` statement. + * + * It registers the head segment to a context of `return`. + * It makes new unreachable segment, then it set the head with the segment. + * + * @returns {void} + */ + makeReturn() { + const forkContext = this.forkContext; + + if (forkContext.reachable) { + getReturnContext(this).returnedForkContext.add(forkContext.head); + forkContext.replaceHead(forkContext.makeUnreachable(-1, -1)); + } + } + + /** + * Makes a path for a `throw` statement. + * + * It registers the head segment to a context of `throw`. + * It makes new unreachable segment, then it set the head with the segment. + * + * @returns {void} + */ + makeThrow() { + const forkContext = this.forkContext; + + if (forkContext.reachable) { + getThrowContext(this).thrownForkContext.add(forkContext.head); + forkContext.replaceHead(forkContext.makeUnreachable(-1, -1)); + } + } + + /** + * Makes the final path. + * @returns {void} + */ + makeFinal() { + const segments = this.currentSegments; + + if (segments.length > 0 && segments[0].reachable) { + this.returnedForkContext.add(segments); + } + } +} + +module.exports = CodePathState; diff --git a/tools/node_modules/eslint/lib/code-path-analysis/code-path.js b/tools/node_modules/eslint/lib/code-path-analysis/code-path.js new file mode 100644 index 0000000000..709a111189 --- /dev/null +++ b/tools/node_modules/eslint/lib/code-path-analysis/code-path.js @@ -0,0 +1,234 @@ +/** + * @fileoverview A class of the code path. + * @author Toru Nagashima + */ + +"use strict"; + +//------------------------------------------------------------------------------ +// Requirements +//------------------------------------------------------------------------------ + +const CodePathState = require("./code-path-state"); +const IdGenerator = require("./id-generator"); + +//------------------------------------------------------------------------------ +// Public Interface +//------------------------------------------------------------------------------ + +/** + * A code path. + */ +class CodePath { + + /** + * @param {string} id - An identifier. + * @param {CodePath|null} upper - The code path of the upper function scope. + * @param {Function} onLooped - A callback function to notify looping. + */ + constructor(id, upper, onLooped) { + + /** + * The identifier of this code path. + * Rules use it to store additional information of each rule. + * @type {string} + */ + this.id = id; + + /** + * The code path of the upper function scope. + * @type {CodePath|null} + */ + this.upper = upper; + + /** + * The code paths of nested function scopes. + * @type {CodePath[]} + */ + this.childCodePaths = []; + + // Initializes internal state. + Object.defineProperty( + this, + "internal", + { value: new CodePathState(new IdGenerator(`${id}_`), onLooped) } + ); + + // Adds this into `childCodePaths` of `upper`. + if (upper) { + upper.childCodePaths.push(this); + } + } + + /** + * Gets the state of a given code path. + * + * @param {CodePath} codePath - A code path to get. + * @returns {CodePathState} The state of the code path. + */ + static getState(codePath) { + return codePath.internal; + } + + /** + * The initial code path segment. + * @type {CodePathSegment} + */ + get initialSegment() { + return this.internal.initialSegment; + } + + /** + * Final code path segments. + * This array is a mix of `returnedSegments` and `thrownSegments`. + * @type {CodePathSegment[]} + */ + get finalSegments() { + return this.internal.finalSegments; + } + + /** + * Final code path segments which is with `return` statements. + * This array contains the last path segment if it's reachable. + * Since the reachable last path returns `undefined`. + * @type {CodePathSegment[]} + */ + get returnedSegments() { + return this.internal.returnedForkContext; + } + + /** + * Final code path segments which is with `throw` statements. + * @type {CodePathSegment[]} + */ + get thrownSegments() { + return this.internal.thrownForkContext; + } + + /** + * Current code path segments. + * @type {CodePathSegment[]} + */ + get currentSegments() { + return this.internal.currentSegments; + } + + /** + * Traverses all segments in this code path. + * + * codePath.traverseSegments(function(segment, controller) { + * // do something. + * }); + * + * This method enumerates segments in order from the head. + * + * The `controller` object has two methods. + * + * - `controller.skip()` - Skip the following segments in this branch. + * - `controller.break()` - Skip all following segments. + * + * @param {Object} [options] - Omittable. + * @param {CodePathSegment} [options.first] - The first segment to traverse. + * @param {CodePathSegment} [options.last] - The last segment to traverse. + * @param {Function} callback - A callback function. + * @returns {void} + */ + traverseSegments(options, callback) { + if (typeof options === "function") { + callback = options; + options = null; + } + + options = options || {}; + const startSegment = options.first || this.internal.initialSegment; + const lastSegment = options.last; + + let item = null; + let index = 0; + let end = 0; + let segment = null; + const visited = Object.create(null); + const stack = [[startSegment, 0]]; + let skippedSegment = null; + let broken = false; + const controller = { + skip() { + if (stack.length <= 1) { + broken = true; + } else { + skippedSegment = stack[stack.length - 2][0]; + } + }, + break() { + broken = true; + } + }; + + /** + * Checks a given previous segment has been visited. + * @param {CodePathSegment} prevSegment - A previous segment to check. + * @returns {boolean} `true` if the segment has been visited. + */ + function isVisited(prevSegment) { + return ( + visited[prevSegment.id] || + segment.isLoopedPrevSegment(prevSegment) + ); + } + + while (stack.length > 0) { + item = stack[stack.length - 1]; + segment = item[0]; + index = item[1]; + + if (index === 0) { + + // Skip if this segment has been visited already. + if (visited[segment.id]) { + stack.pop(); + continue; + } + + // Skip if all previous segments have not been visited. + if (segment !== startSegment && + segment.prevSegments.length > 0 && + !segment.prevSegments.every(isVisited) + ) { + stack.pop(); + continue; + } + + // Reset the flag of skipping if all branches have been skipped. + if (skippedSegment && segment.prevSegments.indexOf(skippedSegment) !== -1) { + skippedSegment = null; + } + visited[segment.id] = true; + + // Call the callback when the first time. + if (!skippedSegment) { + callback.call(this, segment, controller); + if (segment === lastSegment) { + controller.skip(); + } + if (broken) { + break; + } + } + } + + // Update the stack. + end = segment.nextSegments.length - 1; + if (index < end) { + item[1] += 1; + stack.push([segment.nextSegments[index], 0]); + } else if (index === end) { + item[0] = segment.nextSegments[index]; + item[1] = 0; + } else { + stack.pop(); + } + } + } +} + +module.exports = CodePath; diff --git a/tools/node_modules/eslint/lib/code-path-analysis/debug-helpers.js b/tools/node_modules/eslint/lib/code-path-analysis/debug-helpers.js new file mode 100644 index 0000000000..9af985ce85 --- /dev/null +++ b/tools/node_modules/eslint/lib/code-path-analysis/debug-helpers.js @@ -0,0 +1,200 @@ +/** + * @fileoverview Helpers to debug for code path analysis. + * @author Toru Nagashima + */ + +"use strict"; + +//------------------------------------------------------------------------------ +// Requirements +//------------------------------------------------------------------------------ + +const debug = require("debug")("eslint:code-path"); + +//------------------------------------------------------------------------------ +// Helpers +//------------------------------------------------------------------------------ + +/** + * Gets id of a given segment. + * @param {CodePathSegment} segment - A segment to get. + * @returns {string} Id of the segment. + */ +/* istanbul ignore next */ +function getId(segment) { // eslint-disable-line require-jsdoc + return segment.id + (segment.reachable ? "" : "!"); +} + +//------------------------------------------------------------------------------ +// Public Interface +//------------------------------------------------------------------------------ + +module.exports = { + + /** + * A flag that debug dumping is enabled or not. + * @type {boolean} + */ + enabled: debug.enabled, + + /** + * Dumps given objects. + * + * @param {...any} args - objects to dump. + * @returns {void} + */ + dump: debug, + + /** + * Dumps the current analyzing state. + * + * @param {ASTNode} node - A node to dump. + * @param {CodePathState} state - A state to dump. + * @param {boolean} leaving - A flag whether or not it's leaving + * @returns {void} + */ + dumpState: !debug.enabled ? debug : /* istanbul ignore next */ function(node, state, leaving) { + for (let i = 0; i < state.currentSegments.length; ++i) { + const segInternal = state.currentSegments[i].internal; + + if (leaving) { + segInternal.exitNodes.push(node); + } else { + segInternal.nodes.push(node); + } + } + + debug([ + `${state.currentSegments.map(getId).join(",")})`, + `${node.type}${leaving ? ":exit" : ""}` + ].join(" ")); + }, + + /** + * Dumps a DOT code of a given code path. + * The DOT code can be visialized with Graphvis. + * + * @param {CodePath} codePath - A code path to dump. + * @returns {void} + * @see http://www.graphviz.org + * @see http://www.webgraphviz.com + */ + dumpDot: !debug.enabled ? debug : /* istanbul ignore next */ function(codePath) { + let text = + "\n" + + "digraph {\n" + + "node[shape=box,style=\"rounded,filled\",fillcolor=white];\n" + + "initial[label=\"\",shape=circle,style=filled,fillcolor=black,width=0.25,height=0.25];\n"; + + if (codePath.returnedSegments.length > 0) { + text += "final[label=\"\",shape=doublecircle,style=filled,fillcolor=black,width=0.25,height=0.25];\n"; + } + if (codePath.thrownSegments.length > 0) { + text += "thrown[label=\"✘\",shape=circle,width=0.3,height=0.3,fixedsize];\n"; + } + + const traceMap = Object.create(null); + const arrows = this.makeDotArrows(codePath, traceMap); + + for (const id in traceMap) { // eslint-disable-line guard-for-in + const segment = traceMap[id]; + + text += `${id}[`; + + if (segment.reachable) { + text += "label=\""; + } else { + text += "style=\"rounded,dashed,filled\",fillcolor=\"#FF9800\",label=\"<<unreachable>>\\n"; + } + + if (segment.internal.nodes.length > 0 || segment.internal.exitNodes.length > 0) { + text += [].concat( + segment.internal.nodes.map(node => { + switch (node.type) { + case "Identifier": return `${node.type} (${node.name})`; + case "Literal": return `${node.type} (${node.value})`; + default: return node.type; + } + }), + segment.internal.exitNodes.map(node => { + switch (node.type) { + case "Identifier": return `${node.type}:exit (${node.name})`; + case "Literal": return `${node.type}:exit (${node.value})`; + default: return `${node.type}:exit`; + } + }) + ).join("\\n"); + } else { + text += "????"; + } + + text += "\"];\n"; + } + + text += `${arrows}\n`; + text += "}"; + debug("DOT", text); + }, + + /** + * Makes a DOT code of a given code path. + * The DOT code can be visialized with Graphvis. + * + * @param {CodePath} codePath - A code path to make DOT. + * @param {Object} traceMap - Optional. A map to check whether or not segments had been done. + * @returns {string} A DOT code of the code path. + */ + makeDotArrows(codePath, traceMap) { + const stack = [[codePath.initialSegment, 0]]; + const done = traceMap || Object.create(null); + let lastId = codePath.initialSegment.id; + let text = `initial->${codePath.initialSegment.id}`; + + while (stack.length > 0) { + const item = stack.pop(); + const segment = item[0]; + const index = item[1]; + + if (done[segment.id] && index === 0) { + continue; + } + done[segment.id] = segment; + + const nextSegment = segment.allNextSegments[index]; + + if (!nextSegment) { + continue; + } + + if (lastId === segment.id) { + text += `->${nextSegment.id}`; + } else { + text += `;\n${segment.id}->${nextSegment.id}`; + } + lastId = nextSegment.id; + + stack.unshift([segment, 1 + index]); + stack.push([nextSegment, 0]); + } + + codePath.returnedSegments.forEach(finalSegment => { + if (lastId === finalSegment.id) { + text += "->final"; + } else { + text += `;\n${finalSegment.id}->final`; + } + lastId = null; + }); + + codePath.thrownSegments.forEach(finalSegment => { + if (lastId === finalSegment.id) { + text += "->thrown"; + } else { + text += `;\n${finalSegment.id}->thrown`; + } + lastId = null; + }); + + return `${text};`; + } +}; diff --git a/tools/node_modules/eslint/lib/code-path-analysis/fork-context.js b/tools/node_modules/eslint/lib/code-path-analysis/fork-context.js new file mode 100644 index 0000000000..4fae6bbb1e --- /dev/null +++ b/tools/node_modules/eslint/lib/code-path-analysis/fork-context.js @@ -0,0 +1,262 @@ +/** + * @fileoverview A class to operate forking. + * + * This is state of forking. + * This has a fork list and manages it. + * + * @author Toru Nagashima + */ + +"use strict"; + +//------------------------------------------------------------------------------ +// Requirements +//------------------------------------------------------------------------------ + +const assert = require("assert"), + CodePathSegment = require("./code-path-segment"); + +//------------------------------------------------------------------------------ +// Helpers +//------------------------------------------------------------------------------ + +/** + * Gets whether or not a given segment is reachable. + * + * @param {CodePathSegment} segment - A segment to get. + * @returns {boolean} `true` if the segment is reachable. + */ +function isReachable(segment) { + return segment.reachable; +} + +/** + * Creates new segments from the specific range of `context.segmentsList`. + * + * When `context.segmentsList` is `[[a, b], [c, d], [e, f]]`, `begin` is `0`, and + * `end` is `-1`, this creates `[g, h]`. This `g` is from `a`, `c`, and `e`. + * This `h` is from `b`, `d`, and `f`. + * + * @param {ForkContext} context - An instance. + * @param {number} begin - The first index of the previous segments. + * @param {number} end - The last index of the previous segments. + * @param {Function} create - A factory function of new segments. + * @returns {CodePathSegment[]} New segments. + */ +function makeSegments(context, begin, end, create) { + const list = context.segmentsList; + + if (begin < 0) { + begin = list.length + begin; + } + if (end < 0) { + end = list.length + end; + } + + const segments = []; + + for (let i = 0; i < context.count; ++i) { + const allPrevSegments = []; + + for (let j = begin; j <= end; ++j) { + allPrevSegments.push(list[j][i]); + } + + segments.push(create(context.idGenerator.next(), allPrevSegments)); + } + + return segments; +} + +/** + * `segments` becomes doubly in a `finally` block. Then if a code path exits by a + * control statement (such as `break`, `continue`) from the `finally` block, the + * destination's segments may be half of the source segments. In that case, this + * merges segments. + * + * @param {ForkContext} context - An instance. + * @param {CodePathSegment[]} segments - Segments to merge. + * @returns {CodePathSegment[]} The merged segments. + */ +function mergeExtraSegments(context, segments) { + while (segments.length > context.count) { + const merged = []; + + for (let i = 0, length = segments.length / 2 | 0; i < length; ++i) { + merged.push(CodePathSegment.newNext( + context.idGenerator.next(), + [segments[i], segments[i + length]] + )); + } + segments = merged; + } + return segments; +} + +//------------------------------------------------------------------------------ +// Public Interface +//------------------------------------------------------------------------------ + +/** + * A class to manage forking. + */ +class ForkContext { + + /** + * @param {IdGenerator} idGenerator - An identifier generator for segments. + * @param {ForkContext|null} upper - An upper fork context. + * @param {number} count - A number of parallel segments. + */ + constructor(idGenerator, upper, count) { + this.idGenerator = idGenerator; + this.upper = upper; + this.count = count; + this.segmentsList = []; + } + + /** + * The head segments. + * @type {CodePathSegment[]} + */ + get head() { + const list = this.segmentsList; + + return list.length === 0 ? [] : list[list.length - 1]; + } + + /** + * A flag which shows empty. + * @type {boolean} + */ + get empty() { + return this.segmentsList.length === 0; + } + + /** + * A flag which shows reachable. + * @type {boolean} + */ + get reachable() { + const segments = this.head; + + return segments.length > 0 && segments.some(isReachable); + } + + /** + * Creates new segments from this context. + * + * @param {number} begin - The first index of previous segments. + * @param {number} end - The last index of previous segments. + * @returns {CodePathSegment[]} New segments. + */ + makeNext(begin, end) { + return makeSegments(this, begin, end, CodePathSegment.newNext); + } + + /** + * Creates new segments from this context. + * The new segments is always unreachable. + * + * @param {number} begin - The first index of previous segments. + * @param {number} end - The last index of previous segments. + * @returns {CodePathSegment[]} New segments. + */ + makeUnreachable(begin, end) { + return makeSegments(this, begin, end, CodePathSegment.newUnreachable); + } + + /** + * Creates new segments from this context. + * The new segments don't have connections for previous segments. + * But these inherit the reachable flag from this context. + * + * @param {number} begin - The first index of previous segments. + * @param {number} end - The last index of previous segments. + * @returns {CodePathSegment[]} New segments. + */ + makeDisconnected(begin, end) { + return makeSegments(this, begin, end, CodePathSegment.newDisconnected); + } + + /** + * Adds segments into this context. + * The added segments become the head. + * + * @param {CodePathSegment[]} segments - Segments to add. + * @returns {void} + */ + add(segments) { + assert(segments.length >= this.count, `${segments.length} >= ${this.count}`); + + this.segmentsList.push(mergeExtraSegments(this, segments)); + } + + /** + * Replaces the head segments with given segments. + * The current head segments are removed. + * + * @param {CodePathSegment[]} segments - Segments to add. + * @returns {void} + */ + replaceHead(segments) { + assert(segments.length >= this.count, `${segments.length} >= ${this.count}`); + + this.segmentsList.splice(-1, 1, mergeExtraSegments(this, segments)); + } + + /** + * Adds all segments of a given fork context into this context. + * + * @param {ForkContext} context - A fork context to add. + * @returns {void} + */ + addAll(context) { + assert(context.count === this.count); + + const source = context.segmentsList; + + for (let i = 0; i < source.length; ++i) { + this.segmentsList.push(source[i]); + } + } + + /** + * Clears all secments in this context. + * + * @returns {void} + */ + clear() { + this.segmentsList = []; + } + + /** + * Creates the root fork context. + * + * @param {IdGenerator} idGenerator - An identifier generator for segments. + * @returns {ForkContext} New fork context. + */ + static newRoot(idGenerator) { + const context = new ForkContext(idGenerator, null, 1); + + context.add([CodePathSegment.newRoot(idGenerator.next())]); + + return context; + } + + /** + * Creates an empty fork context preceded by a given context. + * + * @param {ForkContext} parentContext - The parent fork context. + * @param {boolean} forkLeavingPath - A flag which shows inside of `finally` block. + * @returns {ForkContext} New fork context. + */ + static newEmpty(parentContext, forkLeavingPath) { + return new ForkContext( + parentContext.idGenerator, + parentContext, + (forkLeavingPath ? 2 : 1) * parentContext.count + ); + } +} + +module.exports = ForkContext; diff --git a/tools/node_modules/eslint/lib/code-path-analysis/id-generator.js b/tools/node_modules/eslint/lib/code-path-analysis/id-generator.js new file mode 100644 index 0000000000..062058ddc1 --- /dev/null +++ b/tools/node_modules/eslint/lib/code-path-analysis/id-generator.js @@ -0,0 +1,46 @@ +/** + * @fileoverview A class of identifiers generator for code path segments. + * + * Each rule uses the identifier of code path segments to store additional + * information of the code path. + * + * @author Toru Nagashima + */ + +"use strict"; + +//------------------------------------------------------------------------------ +// Public Interface +//------------------------------------------------------------------------------ + +/** + * A generator for unique ids. + */ +class IdGenerator { + + /** + * @param {string} prefix - Optional. A prefix of generated ids. + */ + constructor(prefix) { + this.prefix = String(prefix); + this.n = 0; + } + + /** + * Generates id. + * + * @returns {string} A generated id. + */ + next() { + this.n = 1 + this.n | 0; + + /* istanbul ignore if */ + if (this.n < 0) { + this.n = 1; + } + + return this.prefix + this.n; + } +} + +module.exports = IdGenerator; |