'use strict';
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
// eslint-disable-next-line
const CodePathSegment = require('./code-path-segment');
// eslint-disable-next-line
const 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.includes(segment)) {
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;
}
/* c8 ignore next */
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;
}
/* c8 ignore next */
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[]} unflattenedFromSegments Segments which are source.
* @param {CodePathSegment[]} unflattenedToSegments Segments which are destination.
* @returns {void}
*/
function makeLooped(state, unflattenedFromSegments, unflattenedToSegments) {
const fromSegments = CodePathSegment.flattenUnusedSegments(
unflattenedFromSegments,
);
const toSegments = CodePathSegment.flattenUnusedSegments(
unflattenedToSegments,
);
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);
choiceContext.qqForkContext.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.chainContext = 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, AssignmentExpression (logical assignments only),
* 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 or AssignmentExpression's, this is `"&&"` or `"||"` 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),
qqForkContext: ForkContext.newEmpty(this.forkContext),
processed: false,
};
}
/**
* Pops the last choice context and finalizes it.
* @throws {Error} (Unreachable.)
* @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 '||':
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);
context.qqForkContext.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.qqForkContext.addAll(context.qqForkContext);
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;
/* c8 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.
* @throws {Error} (Unreachable.)
* @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.
*/
let prevForkContext;
switch (context.kind) {
case '&&': // if true then go to the right-hand side.
prevForkContext = context.trueForkContext;
break;
case '||': // if false then go to the right-hand side.
prevForkContext = context.falseForkContext;
break;
case '??': // Both true/false can short-circuit, so needs the third path to go to the right-hand side. That's qqForkContext.
prevForkContext = context.qqForkContext;
break;
default:
throw new Error('unreachable');
}
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.
*/
switch (context.kind) {
case '&&': // the false path can short-circuit.
context.falseForkContext.add(forkContext.head);
break;
case '||': // the true path can short-circuit.
context.trueForkContext.add(forkContext.head);
break;
case '??': // both can short-circuit.
context.trueForkContext.add(forkContext.head);
context.falseForkContext.add(forkContext.head);
break;
default:
throw new Error('unreachable');
}
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.qqForkContext.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));
}
//--------------------------------------------------------------------------
// ChainExpression
//--------------------------------------------------------------------------
/**
* Push a new `ChainExpression` context to the stack.
* This method is called on entering to each `ChainExpression` node.
* This context is used to count forking in the optional chain then merge them on the exiting from the `ChainExpression` node.
* @returns {void}
*/
pushChainContext() {
this.chainContext = {
upper: this.chainContext,
countChoiceContexts: 0,
};
}
/**
* Pop a `ChainExpression` context from the stack.
* This method is called on exiting from each `ChainExpression` node.
* This merges all forks of the last optional chaining.
* @returns {void}
*/
popChainContext() {
const context = this.chainContext;
this.chainContext = context.upper;
// pop all choice contexts of this.
for (let i = context.countChoiceContexts; i > 0; --i) {
this.popChoiceContext();
}
}
/**
* Create a choice context for optional access.
* This method is called on entering to each `(Call|Member)Expression[optional=true]` node.
* This creates a choice context as similar to `LogicalExpression[operator="??"]` node.
* @returns {void}
*/
makeOptionalNode() {
if (this.chainContext) {
this.chainContext.countChoiceContexts += 1;
this.pushChoiceContext('??', false);
}
}
/**
* Create a fork.
* This method is called on entering to the `arguments|property` property of each `(Call|Member)Expression` node.
* @returns {void}
*/
makeOptionalRight() {
if (this.chainContext) {
this.makeLogicalRight();
}
}
//--------------------------------------------------------------------------
// 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.
* @throws {Error} (Unreachable - unknown type.)
* @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;
/* c8 ignore next */
default:
throw new Error(`unknown type: "${type}"`);
}
}
/**
* Pops the last context of a loop statement and finalizes it.
* @throws {Error} (Unreachable - unknown type.)
* @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;
/* c8 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);
if (context) {
context.brokenForkContext.add(forkContext.head);
}
/* c8 ignore next */
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);
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;