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3281 lines (2976 loc) · 133 KB
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/// <reference path="../factory.ts" />
/// <reference path="../visitor.ts" />
// Transforms generator functions into a compatible ES5 representation with similar runtime
// semantics. This is accomplished by first transforming the body of each generator
// function into an intermediate representation that is the compiled into a JavaScript
// switch statement.
//
// Many functions in this transformer will contain comments indicating the expected
// intermediate representation. For illustrative purposes, the following intermediate
// language is used to define this intermediate representation:
//
// .nop - Performs no operation.
// .local NAME, ... - Define local variable declarations.
// .mark LABEL - Mark the location of a label.
// .br LABEL - Jump to a label. If jumping out of a protected
// region, all .finally blocks are executed.
// .brtrue LABEL, (x) - Jump to a label IIF the expression `x` is truthy.
// If jumping out of a protected region, all .finally
// blocks are executed.
// .brfalse LABEL, (x) - Jump to a label IIF the expression `x` is falsey.
// If jumping out of a protected region, all .finally
// blocks are executed.
// .yield (x) - Yield the value of the optional expression `x`.
// Resume at the next label.
// .yieldstar (x) - Delegate yield to the value of the optional
// expression `x`. Resume at the next label.
// NOTE: `x` must be an Iterator, not an Iterable.
// .loop CONTINUE, BREAK - Marks the beginning of a loop. Any "continue" or
// "break" abrupt completions jump to the CONTINUE or
// BREAK labels, respectively.
// .endloop - Marks the end of a loop.
// .with (x) - Marks the beginning of a WithStatement block, using
// the supplied expression.
// .endwith - Marks the end of a WithStatement.
// .switch - Marks the beginning of a SwitchStatement.
// .endswitch - Marks the end of a SwitchStatement.
// .labeled NAME - Marks the beginning of a LabeledStatement with the
// supplied name.
// .endlabeled - Marks the end of a LabeledStatement.
// .try TRY, CATCH, FINALLY, END - Marks the beginning of a protected region, and the
// labels for each block.
// .catch (x) - Marks the beginning of a catch block.
// .finally - Marks the beginning of a finally block.
// .endfinally - Marks the end of a finally block.
// .endtry - Marks the end of a protected region.
// .throw (x) - Throws the value of the expression `x`.
// .return (x) - Returns the value of the expression `x`.
//
// In addition, the illustrative intermediate representation introduces some special
// variables:
//
// %sent% - Either returns the next value sent to the generator,
// returns the result of a delegated yield, or throws
// the exception sent to the generator.
// %error% - Returns the value of the current exception in a
// catch block.
//
// This intermediate representation is then compiled into JavaScript syntax. The resulting
// compilation output looks something like the following:
//
// function f() {
// var /*locals*/;
// /*functions*/
// return __generator(function (state) {
// switch (state.label) {
// /*cases per label*/
// }
// });
// }
//
// Each of the above instructions corresponds to JavaScript emit similar to the following:
//
// .local NAME | var NAME;
// -------------------------------|----------------------------------------------
// .mark LABEL | case LABEL:
// -------------------------------|----------------------------------------------
// .br LABEL | return [3 /*break*/, LABEL];
// -------------------------------|----------------------------------------------
// .brtrue LABEL, (x) | if (x) return [3 /*break*/, LABEL];
// -------------------------------|----------------------------------------------
// .brfalse LABEL, (x) | if (!(x)) return [3, /*break*/, LABEL];
// -------------------------------|----------------------------------------------
// .yield (x) | return [4 /*yield*/, x];
// .mark RESUME | case RESUME:
// a = %sent%; | a = state.sent();
// -------------------------------|----------------------------------------------
// .yieldstar (x) | return [5 /*yield**/, x];
// .mark RESUME | case RESUME:
// a = %sent%; | a = state.sent();
// -------------------------------|----------------------------------------------
// .with (_a) | with (_a) {
// a(); | a();
// | }
// | state.label = LABEL;
// .mark LABEL | case LABEL:
// | with (_a) {
// b(); | b();
// | }
// .endwith |
// -------------------------------|----------------------------------------------
// | case 0:
// | state.trys = [];
// | ...
// .try TRY, CATCH, FINALLY, END |
// .mark TRY | case TRY:
// | state.trys.push([TRY, CATCH, FINALLY, END]);
// .nop |
// a(); | a();
// .br END | return [3 /*break*/, END];
// .catch (e) |
// .mark CATCH | case CATCH:
// | e = state.sent();
// b(); | b();
// .br END | return [3 /*break*/, END];
// .finally |
// .mark FINALLY | case FINALLY:
// c(); | c();
// .endfinally | return [7 /*endfinally*/];
// .endtry |
// .mark END | case END:
/*@internal*/
namespace ts {
type Label = number;
const enum OpCode {
Nop, // No operation, used to force a new case in the state machine
Statement, // A regular javascript statement
Assign, // An assignment
Break, // A break instruction used to jump to a label
BreakWhenTrue, // A break instruction used to jump to a label if a condition evaluates to true
BreakWhenFalse, // A break instruction used to jump to a label if a condition evaluates to false
Yield, // A completion instruction for the `yield` keyword
YieldStar, // A completion instruction for the `yield*` keyword (not implemented, but reserved for future use)
Return, // A completion instruction for the `return` keyword
Throw, // A completion instruction for the `throw` keyword
Endfinally // Marks the end of a `finally` block
}
type OperationArguments = [Label] | [Label, Expression] | [Statement] | [Expression] | [Expression, Expression];
// whether a generated code block is opening or closing at the current operation for a FunctionBuilder
const enum BlockAction {
Open,
Close,
}
// the kind for a generated code block in a FunctionBuilder
const enum CodeBlockKind {
Exception,
With,
Switch,
Loop,
Labeled
}
// the state for a generated code exception block
const enum ExceptionBlockState {
Try,
Catch,
Finally,
Done
}
// A generated code block
type CodeBlock = | ExceptionBlock | LabeledBlock | SwitchBlock | LoopBlock | WithBlock;
// a generated exception block, used for 'try' statements
interface ExceptionBlock {
kind: CodeBlockKind.Exception;
state: ExceptionBlockState;
startLabel: Label;
catchVariable?: Identifier;
catchLabel?: Label;
finallyLabel?: Label;
endLabel: Label;
}
// A generated code that tracks the target for 'break' statements in a LabeledStatement.
interface LabeledBlock {
kind: CodeBlockKind.Labeled;
labelText: string;
isScript: boolean;
breakLabel: Label;
}
// a generated block that tracks the target for 'break' statements in a 'switch' statement
interface SwitchBlock {
kind: CodeBlockKind.Switch;
isScript: boolean;
breakLabel: Label;
}
// a generated block that tracks the targets for 'break' and 'continue' statements, used for iteration statements
interface LoopBlock {
kind: CodeBlockKind.Loop;
continueLabel: Label;
isScript: boolean;
breakLabel: Label;
}
// a generated block associated with a 'with' statement
interface WithBlock {
kind: CodeBlockKind.With;
expression: Identifier;
startLabel: Label;
endLabel: Label;
}
// NOTE: changes to this enum should be reflected in the __generator helper.
const enum Instruction {
Next = 0,
Throw = 1,
Return = 2,
Break = 3,
Yield = 4,
YieldStar = 5,
Catch = 6,
Endfinally = 7,
}
function getInstructionName(instruction: Instruction): string {
switch (instruction) {
case Instruction.Return: return "return";
case Instruction.Break: return "break";
case Instruction.Yield: return "yield";
case Instruction.YieldStar: return "yield*";
case Instruction.Endfinally: return "endfinally";
}
}
export function transformGenerators(context: TransformationContext) {
const {
resumeLexicalEnvironment,
endLexicalEnvironment,
hoistFunctionDeclaration,
hoistVariableDeclaration
} = context;
const compilerOptions = context.getCompilerOptions();
const languageVersion = getEmitScriptTarget(compilerOptions);
const resolver = context.getEmitResolver();
const previousOnSubstituteNode = context.onSubstituteNode;
context.onSubstituteNode = onSubstituteNode;
let renamedCatchVariables: Map<boolean>;
let renamedCatchVariableDeclarations: Identifier[];
let inGeneratorFunctionBody: boolean;
let inStatementContainingYield: boolean;
// The following three arrays store information about generated code blocks.
// All three arrays are correlated by their index. This approach is used over allocating
// objects to store the same information to avoid GC overhead.
//
let blocks: CodeBlock[]; // Information about the code block
let blockOffsets: number[]; // The operation offset at which a code block begins or ends
let blockActions: BlockAction[]; // Whether the code block is opened or closed
let blockStack: CodeBlock[]; // A stack of currently open code blocks
// Labels are used to mark locations in the code that can be the target of a Break (jump)
// operation. These are translated into case clauses in a switch statement.
// The following two arrays are correlated by their index. This approach is used over
// allocating objects to store the same information to avoid GC overhead.
//
let labelOffsets: number[]; // The operation offset at which the label is defined.
let labelExpressions: LiteralExpression[][]; // The NumericLiteral nodes bound to each label.
let nextLabelId = 1; // The next label id to use.
// Operations store information about generated code for the function body. This
// Includes things like statements, assignments, breaks (jumps), and yields.
// The following three arrays are correlated by their index. This approach is used over
// allocating objects to store the same information to avoid GC overhead.
//
let operations: OpCode[]; // The operation to perform.
let operationArguments: OperationArguments[]; // The arguments to the operation.
let operationLocations: TextRange[]; // The source map location for the operation.
let state: Identifier; // The name of the state object used by the generator at runtime.
// The following variables store information used by the `build` function:
//
let blockIndex = 0; // The index of the current block.
let labelNumber = 0; // The current label number.
let labelNumbers: number[][];
let lastOperationWasAbrupt: boolean; // Indicates whether the last operation was abrupt (break/continue).
let lastOperationWasCompletion: boolean; // Indicates whether the last operation was a completion (return/throw).
let clauses: CaseClause[]; // The case clauses generated for labels.
let statements: Statement[]; // The statements for the current label.
let exceptionBlockStack: ExceptionBlock[]; // A stack of containing exception blocks.
let currentExceptionBlock: ExceptionBlock; // The current exception block.
let withBlockStack: WithBlock[]; // A stack containing `with` blocks.
return transformSourceFile;
function transformSourceFile(node: SourceFile) {
if (node.isDeclarationFile || (node.transformFlags & TransformFlags.ContainsGenerator) === 0) {
return node;
}
const visited = visitEachChild(node, visitor, context);
addEmitHelpers(visited, context.readEmitHelpers());
return visited;
}
/**
* Visits a node.
*
* @param node The node to visit.
*/
function visitor(node: Node): VisitResult<Node> {
const transformFlags = node.transformFlags;
if (inStatementContainingYield) {
return visitJavaScriptInStatementContainingYield(node);
}
else if (inGeneratorFunctionBody) {
return visitJavaScriptInGeneratorFunctionBody(node);
}
else if (transformFlags & TransformFlags.Generator) {
return visitGenerator(node);
}
else if (transformFlags & TransformFlags.ContainsGenerator) {
return visitEachChild(node, visitor, context);
}
else {
return node;
}
}
/**
* Visits a node that is contained within a statement that contains yield.
*
* @param node The node to visit.
*/
function visitJavaScriptInStatementContainingYield(node: Node): VisitResult<Node> {
switch (node.kind) {
case SyntaxKind.DoStatement:
return visitDoStatement(<DoStatement>node);
case SyntaxKind.WhileStatement:
return visitWhileStatement(<WhileStatement>node);
case SyntaxKind.SwitchStatement:
return visitSwitchStatement(<SwitchStatement>node);
case SyntaxKind.LabeledStatement:
return visitLabeledStatement(<LabeledStatement>node);
default:
return visitJavaScriptInGeneratorFunctionBody(node);
}
}
/**
* Visits a node that is contained within a generator function.
*
* @param node The node to visit.
*/
function visitJavaScriptInGeneratorFunctionBody(node: Node): VisitResult<Node> {
switch (node.kind) {
case SyntaxKind.FunctionDeclaration:
return visitFunctionDeclaration(<FunctionDeclaration>node);
case SyntaxKind.FunctionExpression:
return visitFunctionExpression(<FunctionExpression>node);
case SyntaxKind.GetAccessor:
case SyntaxKind.SetAccessor:
return visitAccessorDeclaration(<AccessorDeclaration>node);
case SyntaxKind.VariableStatement:
return visitVariableStatement(<VariableStatement>node);
case SyntaxKind.ForStatement:
return visitForStatement(<ForStatement>node);
case SyntaxKind.ForInStatement:
return visitForInStatement(<ForInStatement>node);
case SyntaxKind.BreakStatement:
return visitBreakStatement(<BreakStatement>node);
case SyntaxKind.ContinueStatement:
return visitContinueStatement(<ContinueStatement>node);
case SyntaxKind.ReturnStatement:
return visitReturnStatement(<ReturnStatement>node);
default:
if (node.transformFlags & TransformFlags.ContainsYield) {
return visitJavaScriptContainingYield(node);
}
else if (node.transformFlags & (TransformFlags.ContainsGenerator | TransformFlags.ContainsHoistedDeclarationOrCompletion)) {
return visitEachChild(node, visitor, context);
}
else {
return node;
}
}
}
/**
* Visits a node that contains a YieldExpression.
*
* @param node The node to visit.
*/
function visitJavaScriptContainingYield(node: Node): VisitResult<Node> {
switch (node.kind) {
case SyntaxKind.BinaryExpression:
return visitBinaryExpression(<BinaryExpression>node);
case SyntaxKind.ConditionalExpression:
return visitConditionalExpression(<ConditionalExpression>node);
case SyntaxKind.YieldExpression:
return visitYieldExpression(<YieldExpression>node);
case SyntaxKind.ArrayLiteralExpression:
return visitArrayLiteralExpression(<ArrayLiteralExpression>node);
case SyntaxKind.ObjectLiteralExpression:
return visitObjectLiteralExpression(<ObjectLiteralExpression>node);
case SyntaxKind.ElementAccessExpression:
return visitElementAccessExpression(<ElementAccessExpression>node);
case SyntaxKind.CallExpression:
return visitCallExpression(<CallExpression>node);
case SyntaxKind.NewExpression:
return visitNewExpression(<NewExpression>node);
default:
return visitEachChild(node, visitor, context);
}
}
/**
* Visits a generator function.
*
* @param node The node to visit.
*/
function visitGenerator(node: Node): VisitResult<Node> {
switch (node.kind) {
case SyntaxKind.FunctionDeclaration:
return visitFunctionDeclaration(<FunctionDeclaration>node);
case SyntaxKind.FunctionExpression:
return visitFunctionExpression(<FunctionExpression>node);
default:
Debug.failBadSyntaxKind(node);
return visitEachChild(node, visitor, context);
}
}
/**
* Visits a function declaration.
*
* This will be called when one of the following conditions are met:
* - The function declaration is a generator function.
* - The function declaration is contained within the body of a generator function.
*
* @param node The node to visit.
*/
function visitFunctionDeclaration(node: FunctionDeclaration): Statement {
// Currently, we only support generators that were originally async functions.
if (node.asteriskToken) {
node = setOriginalNode(
setTextRange(
createFunctionDeclaration(
/*decorators*/ undefined,
node.modifiers,
/*asteriskToken*/ undefined,
node.name,
/*typeParameters*/ undefined,
visitParameterList(node.parameters, visitor, context),
/*type*/ undefined,
transformGeneratorFunctionBody(node.body)
),
/*location*/ node
),
node
);
}
else {
const savedInGeneratorFunctionBody = inGeneratorFunctionBody;
const savedInStatementContainingYield = inStatementContainingYield;
inGeneratorFunctionBody = false;
inStatementContainingYield = false;
node = visitEachChild(node, visitor, context);
inGeneratorFunctionBody = savedInGeneratorFunctionBody;
inStatementContainingYield = savedInStatementContainingYield;
}
if (inGeneratorFunctionBody) {
// Function declarations in a generator function body are hoisted
// to the top of the lexical scope and elided from the current statement.
hoistFunctionDeclaration(node);
return undefined;
}
else {
return node;
}
}
/**
* Visits a function expression.
*
* This will be called when one of the following conditions are met:
* - The function expression is a generator function.
* - The function expression is contained within the body of a generator function.
*
* @param node The node to visit.
*/
function visitFunctionExpression(node: FunctionExpression): Expression {
// Currently, we only support generators that were originally async functions.
if (node.asteriskToken) {
node = setOriginalNode(
setTextRange(
createFunctionExpression(
/*modifiers*/ undefined,
/*asteriskToken*/ undefined,
node.name,
/*typeParameters*/ undefined,
visitParameterList(node.parameters, visitor, context),
/*type*/ undefined,
transformGeneratorFunctionBody(node.body)
),
/*location*/ node
),
node
);
}
else {
const savedInGeneratorFunctionBody = inGeneratorFunctionBody;
const savedInStatementContainingYield = inStatementContainingYield;
inGeneratorFunctionBody = false;
inStatementContainingYield = false;
node = visitEachChild(node, visitor, context);
inGeneratorFunctionBody = savedInGeneratorFunctionBody;
inStatementContainingYield = savedInStatementContainingYield;
}
return node;
}
/**
* Visits a get or set accessor declaration.
*
* This will be called when one of the following conditions are met:
* - The accessor is contained within the body of a generator function.
*
* @param node The node to visit.
*/
function visitAccessorDeclaration(node: AccessorDeclaration) {
const savedInGeneratorFunctionBody = inGeneratorFunctionBody;
const savedInStatementContainingYield = inStatementContainingYield;
inGeneratorFunctionBody = false;
inStatementContainingYield = false;
node = visitEachChild(node, visitor, context);
inGeneratorFunctionBody = savedInGeneratorFunctionBody;
inStatementContainingYield = savedInStatementContainingYield;
return node;
}
/**
* Transforms the body of a generator function declaration.
*
* @param node The function body to transform.
*/
function transformGeneratorFunctionBody(body: Block) {
// Save existing generator state
const statements: Statement[] = [];
const savedInGeneratorFunctionBody = inGeneratorFunctionBody;
const savedInStatementContainingYield = inStatementContainingYield;
const savedBlocks = blocks;
const savedBlockOffsets = blockOffsets;
const savedBlockActions = blockActions;
const savedBlockStack = blockStack;
const savedLabelOffsets = labelOffsets;
const savedLabelExpressions = labelExpressions;
const savedNextLabelId = nextLabelId;
const savedOperations = operations;
const savedOperationArguments = operationArguments;
const savedOperationLocations = operationLocations;
const savedState = state;
// Initialize generator state
inGeneratorFunctionBody = true;
inStatementContainingYield = false;
blocks = undefined;
blockOffsets = undefined;
blockActions = undefined;
blockStack = undefined;
labelOffsets = undefined;
labelExpressions = undefined;
nextLabelId = 1;
operations = undefined;
operationArguments = undefined;
operationLocations = undefined;
state = createTempVariable(/*recordTempVariable*/ undefined);
// Build the generator
resumeLexicalEnvironment();
const statementOffset = addPrologue(statements, body.statements, /*ensureUseStrict*/ false, visitor);
transformAndEmitStatements(body.statements, statementOffset);
const buildResult = build();
addRange(statements, endLexicalEnvironment());
statements.push(createReturn(buildResult));
// Restore previous generator state
inGeneratorFunctionBody = savedInGeneratorFunctionBody;
inStatementContainingYield = savedInStatementContainingYield;
blocks = savedBlocks;
blockOffsets = savedBlockOffsets;
blockActions = savedBlockActions;
blockStack = savedBlockStack;
labelOffsets = savedLabelOffsets;
labelExpressions = savedLabelExpressions;
nextLabelId = savedNextLabelId;
operations = savedOperations;
operationArguments = savedOperationArguments;
operationLocations = savedOperationLocations;
state = savedState;
return setTextRange(createBlock(statements, body.multiLine), body);
}
/**
* Visits a variable statement.
*
* This will be called when one of the following conditions are met:
* - The variable statement is contained within the body of a generator function.
*
* @param node The node to visit.
*/
function visitVariableStatement(node: VariableStatement): Statement {
if (node.transformFlags & TransformFlags.ContainsYield) {
transformAndEmitVariableDeclarationList(node.declarationList);
return undefined;
}
else {
// Do not hoist custom prologues.
if (getEmitFlags(node) & EmitFlags.CustomPrologue) {
return node;
}
for (const variable of node.declarationList.declarations) {
hoistVariableDeclaration(<Identifier>variable.name);
}
const variables = getInitializedVariables(node.declarationList);
if (variables.length === 0) {
return undefined;
}
return setSourceMapRange(
createStatement(
inlineExpressions(
map(variables, transformInitializedVariable)
)
),
node
);
}
}
/**
* Visits a binary expression.
*
* This will be called when one of the following conditions are met:
* - The node contains a YieldExpression.
*
* @param node The node to visit.
*/
function visitBinaryExpression(node: BinaryExpression): Expression {
switch (getExpressionAssociativity(node)) {
case Associativity.Left:
return visitLeftAssociativeBinaryExpression(node);
case Associativity.Right:
return visitRightAssociativeBinaryExpression(node);
default:
Debug.fail("Unknown associativity.");
}
}
function isCompoundAssignment(kind: BinaryOperator): kind is CompoundAssignmentOperator {
return kind >= SyntaxKind.FirstCompoundAssignment
&& kind <= SyntaxKind.LastCompoundAssignment;
}
function getOperatorForCompoundAssignment(kind: CompoundAssignmentOperator): BitwiseOperatorOrHigher {
switch (kind) {
case SyntaxKind.PlusEqualsToken: return SyntaxKind.PlusToken;
case SyntaxKind.MinusEqualsToken: return SyntaxKind.MinusToken;
case SyntaxKind.AsteriskEqualsToken: return SyntaxKind.AsteriskToken;
case SyntaxKind.AsteriskAsteriskEqualsToken: return SyntaxKind.AsteriskAsteriskToken;
case SyntaxKind.SlashEqualsToken: return SyntaxKind.SlashToken;
case SyntaxKind.PercentEqualsToken: return SyntaxKind.PercentToken;
case SyntaxKind.LessThanLessThanEqualsToken: return SyntaxKind.LessThanLessThanToken;
case SyntaxKind.GreaterThanGreaterThanEqualsToken: return SyntaxKind.GreaterThanGreaterThanToken;
case SyntaxKind.GreaterThanGreaterThanGreaterThanEqualsToken: return SyntaxKind.GreaterThanGreaterThanGreaterThanToken;
case SyntaxKind.AmpersandEqualsToken: return SyntaxKind.AmpersandToken;
case SyntaxKind.BarEqualsToken: return SyntaxKind.BarToken;
case SyntaxKind.CaretEqualsToken: return SyntaxKind.CaretToken;
}
}
/**
* Visits a right-associative binary expression containing `yield`.
*
* @param node The node to visit.
*/
function visitRightAssociativeBinaryExpression(node: BinaryExpression) {
const { left, right } = node;
if (containsYield(right)) {
let target: Expression;
switch (left.kind) {
case SyntaxKind.PropertyAccessExpression:
// [source]
// a.b = yield;
//
// [intermediate]
// .local _a
// _a = a;
// .yield resumeLabel
// .mark resumeLabel
// _a.b = %sent%;
target = updatePropertyAccess(
<PropertyAccessExpression>left,
cacheExpression(visitNode((<PropertyAccessExpression>left).expression, visitor, isLeftHandSideExpression)),
(<PropertyAccessExpression>left).name
);
break;
case SyntaxKind.ElementAccessExpression:
// [source]
// a[b] = yield;
//
// [intermediate]
// .local _a, _b
// _a = a;
// _b = b;
// .yield resumeLabel
// .mark resumeLabel
// _a[_b] = %sent%;
target = updateElementAccess(<ElementAccessExpression>left,
cacheExpression(visitNode((<ElementAccessExpression>left).expression, visitor, isLeftHandSideExpression)),
cacheExpression(visitNode((<ElementAccessExpression>left).argumentExpression, visitor, isExpression))
);
break;
default:
target = visitNode(left, visitor, isExpression);
break;
}
const operator = node.operatorToken.kind;
if (isCompoundAssignment(operator)) {
return setTextRange(
createAssignment(
target,
setTextRange(
createBinary(
cacheExpression(target),
getOperatorForCompoundAssignment(operator),
visitNode(right, visitor, isExpression)
),
node
)
),
node
);
}
else {
return updateBinary(node, target, visitNode(right, visitor, isExpression));
}
}
return visitEachChild(node, visitor, context);
}
function visitLeftAssociativeBinaryExpression(node: BinaryExpression) {
if (containsYield(node.right)) {
if (isLogicalOperator(node.operatorToken.kind)) {
return visitLogicalBinaryExpression(node);
}
else if (node.operatorToken.kind === SyntaxKind.CommaToken) {
return visitCommaExpression(node);
}
// [source]
// a() + (yield) + c()
//
// [intermediate]
// .local _a
// _a = a();
// .yield resumeLabel
// _a + %sent% + c()
const clone = getMutableClone(node);
clone.left = cacheExpression(visitNode(node.left, visitor, isExpression));
clone.right = visitNode(node.right, visitor, isExpression);
return clone;
}
return visitEachChild(node, visitor, context);
}
/**
* Visits a logical binary expression containing `yield`.
*
* @param node A node to visit.
*/
function visitLogicalBinaryExpression(node: BinaryExpression) {
// Logical binary expressions (`&&` and `||`) are shortcutting expressions and need
// to be transformed as such:
//
// [source]
// x = a() && yield;
//
// [intermediate]
// .local _a
// _a = a();
// .brfalse resultLabel, (_a)
// .yield resumeLabel
// .mark resumeLabel
// _a = %sent%;
// .mark resultLabel
// x = _a;
//
// [source]
// x = a() || yield;
//
// [intermediate]
// .local _a
// _a = a();
// .brtrue resultLabel, (_a)
// .yield resumeLabel
// .mark resumeLabel
// _a = %sent%;
// .mark resultLabel
// x = _a;
const resultLabel = defineLabel();
const resultLocal = declareLocal();
emitAssignment(resultLocal, visitNode(node.left, visitor, isExpression), /*location*/ node.left);
if (node.operatorToken.kind === SyntaxKind.AmpersandAmpersandToken) {
// Logical `&&` shortcuts when the left-hand operand is falsey.
emitBreakWhenFalse(resultLabel, resultLocal, /*location*/ node.left);
}
else {
// Logical `||` shortcuts when the left-hand operand is truthy.
emitBreakWhenTrue(resultLabel, resultLocal, /*location*/ node.left);
}
emitAssignment(resultLocal, visitNode(node.right, visitor, isExpression), /*location*/ node.right);
markLabel(resultLabel);
return resultLocal;
}
/**
* Visits a comma expression containing `yield`.
*
* @param node The node to visit.
*/
function visitCommaExpression(node: BinaryExpression) {
// [source]
// x = a(), yield, b();
//
// [intermediate]
// a();
// .yield resumeLabel
// .mark resumeLabel
// x = %sent%, b();
let pendingExpressions: Expression[] = [];
visit(node.left);
visit(node.right);
return inlineExpressions(pendingExpressions);
function visit(node: Expression) {
if (isBinaryExpression(node) && node.operatorToken.kind === SyntaxKind.CommaToken) {
visit(node.left);
visit(node.right);
}
else {
if (containsYield(node) && pendingExpressions.length > 0) {
emitWorker(OpCode.Statement, [createStatement(inlineExpressions(pendingExpressions))]);
pendingExpressions = [];
}
pendingExpressions.push(visitNode(node, visitor, isExpression));
}
}
}
/**
* Visits a conditional expression containing `yield`.
*
* @param node The node to visit.
*/
function visitConditionalExpression(node: ConditionalExpression): Expression {
// [source]
// x = a() ? yield : b();
//
// [intermediate]
// .local _a
// .brfalse whenFalseLabel, (a())
// .yield resumeLabel
// .mark resumeLabel
// _a = %sent%;
// .br resultLabel
// .mark whenFalseLabel
// _a = b();
// .mark resultLabel
// x = _a;
// We only need to perform a specific transformation if a `yield` expression exists
// in either the `whenTrue` or `whenFalse` branches.
// A `yield` in the condition will be handled by the normal visitor.
if (containsYield(node.whenTrue) || containsYield(node.whenFalse)) {
const whenFalseLabel = defineLabel();
const resultLabel = defineLabel();
const resultLocal = declareLocal();
emitBreakWhenFalse(whenFalseLabel, visitNode(node.condition, visitor, isExpression), /*location*/ node.condition);
emitAssignment(resultLocal, visitNode(node.whenTrue, visitor, isExpression), /*location*/ node.whenTrue);
emitBreak(resultLabel);
markLabel(whenFalseLabel);
emitAssignment(resultLocal, visitNode(node.whenFalse, visitor, isExpression), /*location*/ node.whenFalse);
markLabel(resultLabel);
return resultLocal;
}
return visitEachChild(node, visitor, context);
}
/**
* Visits a `yield` expression.
*
* @param node The node to visit.
*/
function visitYieldExpression(node: YieldExpression): LeftHandSideExpression {
// [source]
// x = yield a();
//
// [intermediate]
// .yield resumeLabel, (a())
// .mark resumeLabel
// x = %sent%;
const resumeLabel = defineLabel();
const expression = visitNode(node.expression, visitor, isExpression);
if (node.asteriskToken) {
const iterator = (getEmitFlags(node.expression) & EmitFlags.Iterator) === 0
? createValuesHelper(context, expression, /*location*/ node)
: expression;
emitYieldStar(iterator, /*location*/ node);
}
else {
emitYield(expression, /*location*/ node);
}
markLabel(resumeLabel);
return createGeneratorResume(/*location*/ node);
}
/**
* Visits an ArrayLiteralExpression that contains a YieldExpression.
*
* @param node The node to visit.
*/
function visitArrayLiteralExpression(node: ArrayLiteralExpression) {
return visitElements(node.elements, /*leadingElement*/ undefined, /*location*/ undefined, node.multiLine);
}
/**
* Visits an array of expressions containing one or more YieldExpression nodes
* and returns an expression for the resulting value.
*
* @param elements The elements to visit.
* @param multiLine Whether array literals created should be emitted on multiple lines.
*/
function visitElements(elements: NodeArray<Expression>, leadingElement?: Expression, location?: TextRange, multiLine?: boolean) {
// [source]
// ar = [1, yield, 2];
//
// [intermediate]
// .local _a
// _a = [1];
// .yield resumeLabel
// .mark resumeLabel
// ar = _a.concat([%sent%, 2]);
const numInitialElements = countInitialNodesWithoutYield(elements);
let temp: Identifier;
if (numInitialElements > 0) {
temp = declareLocal();
const initialElements = visitNodes(elements, visitor, isExpression, 0, numInitialElements);
emitAssignment(temp,
createArrayLiteral(
leadingElement
? [leadingElement, ...initialElements]
: initialElements
)
);
leadingElement = undefined;
}
const expressions = reduceLeft(elements, reduceElement, <Expression[]>[], numInitialElements);
return temp