@babel/types#ForOfStatement TypeScript Examples
The following examples show how to use
@babel/types#ForOfStatement.
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Example #1
| Source File: cook.ts From next-core with GNU General Public License v3.0 | 5 votes |
|
/** For next-core internal usage only. */
export function cook(
rootAst: FunctionDeclaration | Expression,
codeSource: string,
{ rules, globalVariables = {}, hooks = {} }: CookOptions = {}
): unknown {
const expressionOnly = rootAst.type !== "FunctionDeclaration";
const rootEnv = new DeclarativeEnvironment(null);
const rootContext = new ExecutionContext();
rootContext.VariableEnvironment = rootEnv;
rootContext.LexicalEnvironment = rootEnv;
const executionContextStack = [rootContext];
for (const [key, value] of Object.entries(globalVariables)) {
rootEnv.CreateImmutableBinding(key, true);
rootEnv.InitializeBinding(key, value);
}
const TemplateMap = new WeakMap<TemplateLiteral, string[]>();
// https://tc39.es/ecma262/#sec-gettemplateobject
function GetTemplateObject(templateLiteral: TemplateLiteral): string[] {
const memo = TemplateMap.get(templateLiteral);
if (memo) {
return memo;
}
const rawObj = templateLiteral.quasis.map((quasi) => quasi.value.raw);
const template = templateLiteral.quasis.map((quasi) => quasi.value.cooked);
Object.freeze(rawObj);
Object.defineProperty(template, "raw", {
value: rawObj,
writable: false,
enumerable: false,
configurable: false,
});
Object.freeze(template);
TemplateMap.set(templateLiteral, template);
return template;
}
function Evaluate(
node: EstreeNode,
optionalChainRef?: OptionalChainRef
): CompletionRecord {
hooks.beforeEvaluate?.(node);
// Expressions:
switch (node.type) {
case "ArrayExpression": {
// https://tc39.es/ecma262/#sec-array-initializer
const array = [];
for (const element of node.elements) {
if (!element) {
array.length += 1;
} else if (element.type === "SpreadElement") {
const spreadValues = GetValue(
Evaluate(element.argument)
) as unknown[];
array.push(...spreadValues);
} else {
array.push(GetValue(Evaluate(element)));
}
}
return NormalCompletion(array);
}
case "ArrowFunctionExpression": {
// https://tc39.es/ecma262/#sec-arrow-function-definitions
ThrowIfFunctionIsInvalid(node);
const closure = InstantiateArrowFunctionExpression(node);
return NormalCompletion(closure);
}
case "BinaryExpression": {
const leftRef = Evaluate(node.left);
const leftValue = GetValue(leftRef);
const rightRef = Evaluate(node.right).Value;
const rightValue = GetValue(rightRef);
if (expressionOnly && (node.operator as unknown) === "|>") {
// Minimal pipeline operator is supported only in expression-only mode.
// See https://tc39.es/proposal-pipeline-operator
// and https://github.com/tc39/proposal-pipeline-operator
if (typeof rightValue !== "function") {
const funcName = codeSource.substring(
node.right.start,
node.right.end
);
throw new TypeError(`${funcName} is not a function`);
}
let thisValue;
if (rightRef instanceof ReferenceRecord) {
if (IsPropertyReference(rightRef)) {
thisValue = rightRef.Base;
}
}
return NormalCompletion(
(rightValue as unknown as SimpleFunction).call(thisValue, leftValue)
);
}
// https://tc39.es/ecma262/#sec-additive-operators
const result = ApplyStringOrNumericBinaryOperator(
leftValue as number,
node.operator,
rightValue as number
);
return NormalCompletion(result);
}
case "CallExpression": {
// https://tc39.es/ecma262/#sec-function-calls
const ref = Evaluate(node.callee, optionalChainRef)
.Value as ReferenceRecord;
const func = GetValue(ref) as SimpleFunction;
if (
(func === undefined || func === null) &&
(node.optional || optionalChainRef?.skipped)
) {
optionalChainRef.skipped = true;
return NormalCompletion(undefined);
}
sanitize(func);
return EvaluateCall(func, ref, node.arguments, node.callee);
}
case "ChainExpression":
// https://tc39.es/ecma262/#sec-optional-chains
return Evaluate(node.expression, {});
case "ConditionalExpression":
// https://tc39.es/ecma262/#sec-conditional-operator
return NormalCompletion(
GetValue(
Evaluate(
GetValue(Evaluate(node.test)) ? node.consequent : node.alternate
)
)
);
case "Identifier":
// https://tc39.es/ecma262/#sec-identifiers
return NormalCompletion(ResolveBinding(node.name));
case "Literal": {
// https://tc39.es/ecma262/#sec-primary-expression-literals
if (node.regex) {
if (node.value === null) {
// Invalid regular expression fails silently in @babel/parser.
throw new SyntaxError(`Invalid regular expression: ${node.raw}`);
}
if (node.regex.flags.includes("u")) {
// Currently unicode flag is not fully supported across major browsers.
throw new SyntaxError(
`Unsupported unicode flag in regular expression: ${node.raw}`
);
}
}
return NormalCompletion(node.value);
}
case "LogicalExpression": {
// https://tc39.es/ecma262/#sec-binary-logical-operators
const leftValue = GetValue(Evaluate(node.left));
switch (node.operator) {
case "&&":
return NormalCompletion(
leftValue && GetValue(Evaluate(node.right))
);
case "||":
return NormalCompletion(
leftValue || GetValue(Evaluate(node.right))
);
case "??":
return NormalCompletion(
leftValue ?? GetValue(Evaluate(node.right))
);
// istanbul ignore next
default:
throw new SyntaxError(
// eslint-disable-next-line @typescript-eslint/ban-ts-comment
// @ts-ignore never reach here.
`Unsupported logical operator '${node.operator}'`
);
}
}
case "MemberExpression": {
// https://tc39.es/ecma262/#sec-property-accessors
const baseReference = Evaluate(node.object, optionalChainRef)
.Value as ReferenceRecord;
const baseValue = GetValue(baseReference) as Record<
PropertyKey,
unknown
>;
if (
(baseValue === undefined || baseValue === null) &&
(node.optional || optionalChainRef?.skipped)
) {
optionalChainRef.skipped = true;
return NormalCompletion(undefined);
}
sanitize(baseValue);
const result = node.computed
? EvaluatePropertyAccessWithExpressionKey(
baseValue,
node.property as Expression,
true
)
: EvaluatePropertyAccessWithIdentifierKey(
baseValue,
node.property as Identifier,
true
);
sanitize(result);
return NormalCompletion(result);
}
case "NewExpression":
// https://tc39.es/ecma262/#sec-new-operator
return EvaluateNew(node.callee, node.arguments);
case "ObjectExpression": {
// https://tc39.es/ecma262/#sec-object-initializer
const object: Record<PropertyKey, unknown> = {};
for (const prop of (node as EstreeObjectExpression).properties) {
if (prop.type === "SpreadElement") {
const fromValue = GetValue(Evaluate(prop.argument));
CopyDataProperties(object, fromValue, new Set());
} else {
if (prop.kind !== "init") {
throw new SyntaxError("Unsupported object getter/setter");
}
const propName =
!prop.computed && prop.key.type === "Identifier"
? prop.key.name
: EvaluateComputedPropertyName(prop.key);
if (propName === "__proto__") {
throw new TypeError(
"Setting '__proto__' property is not allowed"
);
}
object[propName] = GetValue(Evaluate(prop.value));
}
}
return NormalCompletion(object);
}
case "SequenceExpression": {
// https://tc39.es/ecma262/#sec-comma-operator
let result: CompletionRecord;
for (const expr of node.expressions) {
result = NormalCompletion(GetValue(Evaluate(expr)));
}
return result;
}
case "TemplateLiteral": {
// https://tc39.es/ecma262/#sec-template-literals
const chunks: string[] = [node.quasis[0].value.cooked];
let index = 0;
for (const expr of node.expressions) {
const val = GetValue(Evaluate(expr));
chunks.push(String(val));
chunks.push(node.quasis[(index += 1)].value.cooked);
}
return NormalCompletion(chunks.join(""));
}
case "TaggedTemplateExpression": {
// https://tc39.es/ecma262/#sec-tagged-templates
const tagRef = Evaluate(node.tag).Value as ReferenceRecord;
const tagFunc = GetValue(tagRef) as SimpleFunction;
sanitize(tagFunc);
return EvaluateCall(tagFunc, tagRef, node.quasi, node.tag);
}
case "UnaryExpression": {
// https://tc39.es/ecma262/#sec-unary-operators
const ref = Evaluate(node.argument).Value as ReferenceRecord;
if (!expressionOnly && node.operator === "delete") {
// Delete operator is supported only in function mode.
if (!(ref instanceof ReferenceRecord)) {
return NormalCompletion(true);
}
// istanbul ignore else
if (IsPropertyReference(ref)) {
const deleteStatus = delete (
ref.Base as Record<PropertyKey, unknown>
)[ref.ReferenceName];
return NormalCompletion(deleteStatus);
}
// Should never reach here in strict mode.
}
if (node.operator === "typeof") {
if (ref instanceof ReferenceRecord && ref.Base === "unresolvable") {
return NormalCompletion("undefined");
}
return NormalCompletion(typeof GetValue(ref));
}
return NormalCompletion(
ApplyUnaryOperator(GetValue(ref), node.operator)
);
}
}
if (!expressionOnly) {
// Statements and assignments:
switch (node.type) {
case "AssignmentExpression": {
// https://tc39.es/ecma262/#sec-assignment-operators
if (node.operator === "=") {
if (
!(
node.left.type === "ArrayPattern" ||
node.left.type === "ObjectPattern"
)
) {
const lref = Evaluate(node.left).Value as ReferenceRecord;
// Todo: IsAnonymousFunctionDefinition(lref)
const rref = Evaluate(node.right);
const rval = GetValue(rref);
PutValue(lref, rval);
return NormalCompletion(rval);
}
const rref = Evaluate(node.right);
const rval = GetValue(rref) as string | number;
DestructuringAssignmentEvaluation(node.left, rval);
return NormalCompletion(rval);
}
// Operators other than `=`.
const lref = Evaluate(node.left).Value as ReferenceRecord;
const lval = GetValue(lref) as string | number;
const rref = Evaluate(node.right);
const rval = GetValue(rref) as string | number;
const r = ApplyStringOrNumericAssignment(lval, node.operator, rval);
PutValue(lref, r);
return NormalCompletion(r);
}
case "BlockStatement": {
// https://tc39.es/ecma262/#sec-block
if (!node.body.length) {
return NormalCompletion(Empty);
}
const oldEnv = getRunningContext().LexicalEnvironment;
const blockEnv = new DeclarativeEnvironment(oldEnv);
BlockDeclarationInstantiation(node.body, blockEnv);
getRunningContext().LexicalEnvironment = blockEnv;
const blockValue = EvaluateStatementList(node.body);
getRunningContext().LexicalEnvironment = oldEnv;
return blockValue;
}
case "BreakStatement":
// https://tc39.es/ecma262/#sec-break-statement
return new CompletionRecord("break", Empty);
case "ContinueStatement":
// https://tc39.es/ecma262/#sec-continue-statement
return new CompletionRecord("continue", Empty);
case "EmptyStatement":
// https://tc39.es/ecma262/#sec-empty-statement
return NormalCompletion(Empty);
case "DoWhileStatement":
// https://tc39.es/ecma262/#sec-do-while-statement
return EvaluateBreakableStatement(DoWhileLoopEvaluation(node));
case "ExpressionStatement":
case "TSAsExpression":
// https://tc39.es/ecma262/#sec-expression-statement
return Evaluate(node.expression);
case "ForInStatement":
case "ForOfStatement":
// https://tc39.es/ecma262/#sec-for-in-and-for-of-statements
return EvaluateBreakableStatement(ForInOfLoopEvaluation(node));
case "ForStatement":
// https://tc39.es/ecma262/#sec-for-statement
return EvaluateBreakableStatement(ForLoopEvaluation(node));
case "FunctionDeclaration":
// https://tc39.es/ecma262/#sec-function-definitions
return NormalCompletion(Empty);
case "FunctionExpression":
// https://tc39.es/ecma262/#sec-function-defining-expressions
ThrowIfFunctionIsInvalid(node);
return NormalCompletion(InstantiateOrdinaryFunctionExpression(node));
case "IfStatement":
// https://tc39.es/ecma262/#sec-if-statement
return GetValue(Evaluate(node.test))
? (hooks.beforeBranch?.(node, "if"),
UpdateEmpty(Evaluate(node.consequent), undefined))
: (hooks.beforeBranch?.(node, "else"), node.alternate)
? UpdateEmpty(Evaluate(node.alternate), undefined)
: NormalCompletion(undefined);
case "ReturnStatement": {
// https://tc39.es/ecma262/#sec-return-statement
let v: unknown;
if (node.argument) {
const exprRef = Evaluate(node.argument);
v = GetValue(exprRef);
}
return new CompletionRecord("return", v);
}
case "ThrowStatement":
// https://tc39.es/ecma262/#sec-throw-statement
throw GetValue(Evaluate(node.argument));
case "UpdateExpression": {
// https://tc39.es/ecma262/#sec-update-expressions
const lhs = Evaluate(node.argument).Value as ReferenceRecord;
const oldValue = Number(GetValue(lhs));
const newValue = node.operator === "++" ? oldValue + 1 : oldValue - 1;
PutValue(lhs, newValue);
return NormalCompletion(node.prefix ? newValue : oldValue);
}
case "SwitchCase":
return EvaluateStatementList(node.consequent);
case "SwitchStatement": {
// https://tc39.es/ecma262/#sec-switch-statement
const exprRef = Evaluate(node.discriminant);
const switchValue = GetValue(exprRef);
const oldEnv = getRunningContext().LexicalEnvironment;
const blockEnv = new DeclarativeEnvironment(oldEnv);
BlockDeclarationInstantiation(node.cases, blockEnv);
getRunningContext().LexicalEnvironment = blockEnv;
const R = CaseBlockEvaluation(node.cases, switchValue);
getRunningContext().LexicalEnvironment = oldEnv;
return EvaluateBreakableStatement(R);
}
case "TryStatement": {
// https://tc39.es/ecma262/#sec-try-statement
let R: CompletionRecord;
try {
R = Evaluate(node.block);
} catch (error) {
if (node.handler) {
hooks.beforeEvaluate?.(node.handler);
R = CatchClauseEvaluation(node.handler, error);
} else {
throw error;
}
} finally {
if (node.finalizer) {
const F = Evaluate(node.finalizer);
if (F.Type !== "normal") {
R = F;
}
}
}
return R;
}
case "VariableDeclaration": {
// https://tc39.es/ecma262/#sec-declarations-and-the-variable-statement
let result: CompletionRecord;
for (const declarator of node.declarations) {
if (!declarator.init) {
// Assert: a declarator without init is always an identifier.
if (node.kind === "var") {
result = NormalCompletion(Empty);
} else {
const lhs = ResolveBinding((declarator.id as Identifier).name);
result = InitializeReferencedBinding(lhs, undefined);
}
} else if (declarator.id.type === "Identifier") {
const bindingId = declarator.id.name;
const lhs = ResolveBinding(bindingId);
// Todo: IsAnonymousFunctionDefinition(Initializer)
const rhs = Evaluate(declarator.init);
const value = GetValue(rhs);
result =
node.kind === "var"
? PutValue(lhs, value)
: InitializeReferencedBinding(lhs, value);
} else {
const rhs = Evaluate(declarator.init);
const rval = GetValue(rhs);
result = BindingInitialization(
declarator.id,
rval,
node.kind === "var"
? undefined
: getRunningContext().LexicalEnvironment
);
}
}
return result;
}
case "WhileStatement":
// https://tc39.es/ecma262/#sec-while-statement
return EvaluateBreakableStatement(WhileLoopEvaluation(node));
}
}
// eslint-disable-next-line no-console
throw new SyntaxError(`Unsupported node type \`${node.type}\``);
}
// https://tc39.es/ecma262/#sec-execution-contexts
function getRunningContext(): ExecutionContext {
return executionContextStack[executionContextStack.length - 1];
}
// https://tc39.es/ecma262/#sec-resolvebinding
function ResolveBinding(
name: string,
env?: EnvironmentRecord
): ReferenceRecord {
if (!env) {
env = getRunningContext().LexicalEnvironment;
}
return GetIdentifierReference(env, name, true);
}
// Try statements.
// https://tc39.es/ecma262/#sec-runtime-semantics-catchclauseevaluation
function CatchClauseEvaluation(
node: CatchClause,
thrownValue: unknown
): CompletionRecord {
const oldEnv = getRunningContext().LexicalEnvironment;
const catchEnv = new DeclarativeEnvironment(oldEnv);
for (const argName of collectBoundNames(node.param)) {
catchEnv.CreateMutableBinding(argName, false);
}
getRunningContext().LexicalEnvironment = catchEnv;
BindingInitialization(node.param, thrownValue, catchEnv);
const B = Evaluate(node.body);
getRunningContext().LexicalEnvironment = oldEnv;
return B;
}
// Iteration statements and switch statements.
// https://tc39.es/ecma262/#prod-BreakableStatement
function EvaluateBreakableStatement(
stmtResult: CompletionRecord
): CompletionRecord {
return stmtResult.Type === "break"
? stmtResult.Value === Empty
? NormalCompletion(undefined)
: NormalCompletion(stmtResult.Value)
: stmtResult;
}
// Switch statements.
// https://tc39.es/ecma262/#sec-runtime-semantics-caseblockevaluation
function CaseBlockEvaluation(
cases: SwitchCase[],
input: unknown
): CompletionRecord {
let V: unknown;
const defaultCaseIndex = cases.findIndex((switchCase) => !switchCase.test);
const hasDefaultCase = defaultCaseIndex >= 0;
const A = hasDefaultCase ? cases.slice(0, defaultCaseIndex) : cases;
let found = false;
for (const C of A) {
if (!found) {
found = CaseClauseIsSelected(C, input);
}
if (found) {
const R = Evaluate(C);
if (R.Value !== Empty) {
V = R.Value;
}
if (R.Type !== "normal") {
return UpdateEmpty(R, V);
}
}
}
if (!hasDefaultCase) {
return NormalCompletion(V);
}
let foundInB = false;
const B = cases.slice(defaultCaseIndex + 1);
if (!found) {
for (const C of B) {
if (!foundInB) {
foundInB = CaseClauseIsSelected(C, input);
}
if (foundInB) {
const R = Evaluate(C);
if (R.Value !== Empty) {
V = R.Value;
}
if (R.Type !== "normal") {
return UpdateEmpty(R, V);
}
}
}
}
if (foundInB) {
return NormalCompletion(V);
}
const R = Evaluate(cases[defaultCaseIndex]);
if (R.Value !== Empty) {
V = R.Value;
}
if (R.Type !== "normal") {
return UpdateEmpty(R, V);
}
// NOTE: The following is another complete iteration of the second CaseClauses.
for (const C of B) {
const R = Evaluate(C);
if (R.Value !== Empty) {
V = R.Value;
}
if (R.Type !== "normal") {
return UpdateEmpty(R, V);
}
}
return NormalCompletion(V);
}
// https://tc39.es/ecma262/#sec-runtime-semantics-caseclauseisselected
function CaseClauseIsSelected(C: SwitchCase, input: unknown): boolean {
const clauseSelector = GetValue(Evaluate(C.test));
return input === clauseSelector;
}
// While statements.
// https://tc39.es/ecma262/#sec-runtime-semantics-whileloopevaluation
function WhileLoopEvaluation(node: WhileStatement): CompletionRecord {
let V: unknown;
// eslint-disable-next-line no-constant-condition
while (true) {
const exprValue = GetValue(Evaluate(node.test));
if (!exprValue) {
return NormalCompletion(V);
}
const stmtResult = Evaluate(node.body);
if (!LoopContinues(stmtResult)) {
return UpdateEmpty(stmtResult, V);
}
if (stmtResult.Value !== Empty) {
V = stmtResult.Value;
}
}
}
// Do-while Statements.
// https://tc39.es/ecma262/#sec-runtime-semantics-dowhileloopevaluation
function DoWhileLoopEvaluation(node: DoWhileStatement): CompletionRecord {
let V: unknown;
// eslint-disable-next-line no-constant-condition
while (true) {
const stmtResult = Evaluate(node.body);
if (!LoopContinues(stmtResult)) {
return UpdateEmpty(stmtResult, V);
}
if (stmtResult.Value !== Empty) {
V = stmtResult.Value;
}
const exprValue = GetValue(Evaluate(node.test));
if (!exprValue) {
return NormalCompletion(V);
}
}
}
// For in/of statements.
// https://tc39.es/ecma262/#sec-runtime-semantics-forinofloopevaluation
function ForInOfLoopEvaluation(
node: ForInStatement | ForOfStatement
): CompletionRecord {
const lhs = node.left;
const isVariableDeclaration = lhs.type === "VariableDeclaration";
const lhsKind = isVariableDeclaration
? lhs.kind === "var"
? "varBinding"
: "lexicalBinding"
: "assignment";
const uninitializedBoundNames =
lhsKind === "lexicalBinding" ? collectBoundNames(lhs) : [];
const iterationKind =
node.type === "ForInStatement" ? "enumerate" : "iterate";
const keyResult = ForInOfHeadEvaluation(
uninitializedBoundNames,
node.right,
iterationKind
);
if (keyResult.Type !== "normal") {
// When enumerate, if the target is nil, a break completion will be returned.
return keyResult;
}
return ForInOfBodyEvaluation(
lhs,
node.body,
keyResult.Value as Iterator<unknown>,
iterationKind,
lhsKind
);
}
// https://tc39.es/ecma262/#sec-runtime-semantics-forinofheadevaluation
function ForInOfHeadEvaluation(
uninitializedBoundNames: string[],
expr: Expression,
iterationKind: "enumerate" | "iterate"
): CompletionRecord {
const runningContext = getRunningContext();
const oldEnv = runningContext.LexicalEnvironment;
if (uninitializedBoundNames.length > 0) {
const newEnv = new DeclarativeEnvironment(oldEnv);
for (const name of uninitializedBoundNames) {
newEnv.CreateMutableBinding(name, false);
}
runningContext.LexicalEnvironment = newEnv;
}
const exprRef = Evaluate(expr);
runningContext.LexicalEnvironment = oldEnv;
const exprValue = GetValue(exprRef);
if (iterationKind === "enumerate") {
if (exprValue === null || exprValue === undefined) {
return new CompletionRecord("break", Empty);
}
const iterator = EnumerateObjectProperties(exprValue);
return NormalCompletion(iterator);
}
const iterator = CreateListIteratorRecord(exprValue as Iterable<unknown>);
return NormalCompletion(iterator);
}
function ForInOfBodyEvaluation(
node: VariableDeclaration | EstreeLVal,
stmt: Statement,
iteratorRecord: Iterator<unknown>,
iterationKind: "enumerate" | "iterate",
lhsKind: "varBinding" | "lexicalBinding" | "assignment"
): CompletionRecord {
const lhs =
lhsKind === "assignment"
? (node as EstreeLVal)
: (node as VariableDeclaration).declarations[0].id;
const oldEnv = getRunningContext().LexicalEnvironment;
let V: unknown;
// When `destructuring` is false,
// For `node` whose `kind` is assignment:
// `lhs` is an `Identifier` or a `MemberExpression`,
// Otherwise:
// `lhs` is an `Identifier`.
const destructuring =
lhs.type === "ObjectPattern" || lhs.type === "ArrayPattern";
// eslint-disable-next-line no-constant-condition
while (true) {
const { done, value: nextValue } = iteratorRecord.next();
if (done) {
return NormalCompletion(V);
}
let lhsRef: ReferenceRecord;
let iterationEnv: DeclarativeEnvironment;
if (lhsKind === "lexicalBinding") {
iterationEnv = new DeclarativeEnvironment(oldEnv);
ForDeclarationBindingInstantiation(
node as VariableDeclaration,
iterationEnv
);
getRunningContext().LexicalEnvironment = iterationEnv;
if (!destructuring) {
const [lhsName] = collectBoundNames(lhs);
lhsRef = ResolveBinding(lhsName);
}
} else if (!destructuring) {
lhsRef = Evaluate(lhs).Value as ReferenceRecord;
}
destructuring
? lhsKind === "assignment"
? DestructuringAssignmentEvaluation(lhs, nextValue)
: lhsKind === "varBinding"
? BindingInitialization(lhs, nextValue, undefined)
: BindingInitialization(lhs, nextValue, iterationEnv)
: lhsKind === "lexicalBinding"
? InitializeReferencedBinding(lhsRef, nextValue)
: PutValue(lhsRef, nextValue);
const result = Evaluate(stmt);
getRunningContext().LexicalEnvironment = oldEnv;
if (!LoopContinues(result)) {
const status = UpdateEmpty(result, V);
if (
!(
iterationKind === "enumerate" || iteratorRecord.return === undefined
)
) {
// Perform *IteratorClose*
// https://tc39.es/ecma262/#sec-iteratorclose
const innerResult = iteratorRecord.return();
if (
!innerResult ||
!["object", "function"].includes(typeof innerResult)
) {
throw new TypeError(`Iterator result is not an object`);
}
}
return status;
}
if (result.Value !== Empty) {
V = result.Value;
}
}
}
// https://tc39.es/ecma262/#sec-enumerate-object-properties
function* EnumerateObjectProperties(value: any): Iterator<PropertyKey> {
for (const key in value) {
yield key;
}
}
// For statements.
// https://tc39.es/ecma262/#sec-runtime-semantics-forloopevaluation
function ForLoopEvaluation(node: ForStatement): CompletionRecord {
if (node.init?.type === "VariableDeclaration") {
// `for (var … ; … ; … ) …`
if (node.init.kind === "var") {
Evaluate(node.init);
return ForBodyEvaluation(node.test, node.update, node.body, []);
}
// `for (let/const … ; … ; … ) …`
const oldEnv = getRunningContext().LexicalEnvironment;
const loopEnv = new DeclarativeEnvironment(oldEnv);
const isConst = node.init.kind === "const";
const boundNames = collectBoundNames(node.init);
for (const dn of boundNames) {
if (isConst) {
loopEnv.CreateImmutableBinding(dn, true);
} else {
loopEnv.CreateMutableBinding(dn, false);
}
}
getRunningContext().LexicalEnvironment = loopEnv;
Evaluate(node.init);
const perIterationLets = isConst ? [] : Array.from(boundNames);
const bodyResult = ForBodyEvaluation(
node.test,
node.update,
node.body,
perIterationLets
);
getRunningContext().LexicalEnvironment = oldEnv;
return bodyResult;
}
// `for ( … ; … ; … ) …`
if (node.init) {
const exprRef = Evaluate(node.init);
GetValue(exprRef);
}
return ForBodyEvaluation(node.test, node.update, node.body, []);
}
// https://tc39.es/ecma262/#sec-forbodyevaluation
function ForBodyEvaluation(
test: Expression,
increment: Expression,
stmt: Statement,
perIterationBindings: string[]
): CompletionRecord {
CreatePerIterationEnvironment(perIterationBindings);
let V: unknown;
// eslint-disable-next-line no-constant-condition
while (true) {
if (test) {
const testRef = Evaluate(test);
const testValue = GetValue(testRef);
if (!testValue) {
return NormalCompletion(V);
}
}
const result = Evaluate(stmt) as CompletionRecord;
if (!LoopContinues(result)) {
return UpdateEmpty(result, V);
}
if (result.Value) {
V = result.Value;
}
CreatePerIterationEnvironment(perIterationBindings);
if (increment) {
const incRef = Evaluate(increment);
GetValue(incRef);
}
}
}
// https://tc39.es/ecma262/#sec-createperiterationenvironment
function CreatePerIterationEnvironment(
perIterationBindings: string[]
): unknown {
if (perIterationBindings.length === 0) {
return;
}
const lastIterationEnv = getRunningContext().LexicalEnvironment;
const outer = lastIterationEnv.OuterEnv;
const thisIterationEnv = new DeclarativeEnvironment(outer);
for (const bn of perIterationBindings) {
thisIterationEnv.CreateMutableBinding(bn, false);
const lastValue = lastIterationEnv.GetBindingValue(bn, false);
thisIterationEnv.InitializeBinding(bn, lastValue);
}
getRunningContext().LexicalEnvironment = thisIterationEnv;
}
// Destructuring assignments.
// https://tc39.es/ecma262/#sec-runtime-semantics-destructuringassignmentevaluation
function DestructuringAssignmentEvaluation(
pattern: ObjectPattern | EstreeObjectPattern | ArrayPattern,
value: unknown
): CompletionRecord {
if (pattern.type === "ObjectPattern") {
RequireObjectCoercible(value);
if (pattern.properties.length > 0) {
PropertyDestructuringAssignmentEvaluation(
(pattern as EstreeObjectPattern).properties,
value
);
}
return NormalCompletion(Empty);
}
const iteratorRecord = CreateListIteratorRecord(value as Iterable<unknown>);
return IteratorDestructuringAssignmentEvaluation(
pattern.elements,
iteratorRecord
);
}
// https://tc39.es/ecma262/#sec-runtime-semantics-propertydestructuringassignmentevaluation
function PropertyDestructuringAssignmentEvaluation(
properties: (EstreeProperty | RestElement)[],
value: unknown
): void {
const excludedNames = new Set<PropertyKey>();
for (const prop of properties) {
if (prop.type === "Property") {
const propName =
!prop.computed && prop.key.type === "Identifier"
? prop.key.name
: (EvaluateComputedPropertyName(prop.key) as string);
const valueTarget =
prop.value.type === "AssignmentPattern"
? prop.value.left
: prop.value;
if (valueTarget.type === "Identifier") {
const lref = ResolveBinding(valueTarget.name);
let v = GetV(value, propName);
if (prop.value.type === "AssignmentPattern" && v === undefined) {
// Todo(steve): check IsAnonymousFunctionDefinition(Initializer)
const defaultValue = Evaluate(prop.value.right);
v = GetValue(defaultValue);
}
PutValue(lref, v);
excludedNames.add(propName);
} else {
KeyedDestructuringAssignmentEvaluation(prop.value, value, propName);
excludedNames.add(propName);
}
} else {
RestDestructuringAssignmentEvaluation(prop, value, excludedNames);
}
}
}
// https://tc39.es/ecma262/#sec-runtime-semantics-keyeddestructuringassignmentevaluation
function KeyedDestructuringAssignmentEvaluation(
node: EstreeNode,
value: unknown,
propertyName: PropertyKey
): CompletionRecord {
const assignmentTarget =
node.type === "AssignmentPattern" ? node.left : node;
const isObjectOrArray =
assignmentTarget.type === "ArrayPattern" ||
assignmentTarget.type === "ObjectPattern";
let lref;
if (!isObjectOrArray) {
lref = Evaluate(assignmentTarget).Value as ReferenceRecord;
}
const v = GetV(value, propertyName);
let rhsValue;
if (node.type === "AssignmentPattern" && v === undefined) {
// Todo(steve): check IsAnonymousFunctionDefinition(Initializer)
const defaultValue = Evaluate(node.right);
rhsValue = GetValue(defaultValue);
} else {
rhsValue = v;
}
if (isObjectOrArray) {
return DestructuringAssignmentEvaluation(assignmentTarget, rhsValue);
}
return PutValue(lref, rhsValue);
}
// https://tc39.es/ecma262/#sec-runtime-semantics-restdestructuringassignmentevaluation
function RestDestructuringAssignmentEvaluation(
restProperty: RestElement,
value: unknown,
excludedNames: Set<PropertyKey>
): CompletionRecord {
const lref = Evaluate(restProperty.argument).Value as ReferenceRecord;
const restObj = CopyDataProperties({}, value, excludedNames);
return PutValue(lref, restObj);
}
// https://tc39.es/ecma262/#sec-runtime-semantics-iteratordestructuringassignmentevaluation
function IteratorDestructuringAssignmentEvaluation(
elements: PatternLike[],
iteratorRecord: Iterator<unknown>
): CompletionRecord {
let status = NormalCompletion(Empty);
for (const element of elements) {
if (!element) {
iteratorRecord.next();
status = NormalCompletion(Empty);
continue;
}
const assignmentTarget =
element.type === "RestElement"
? element.argument
: element.type === "AssignmentPattern"
? element.left
: element;
const isObjectOrArray =
assignmentTarget.type === "ArrayPattern" ||
assignmentTarget.type === "ObjectPattern";
let lref: ReferenceRecord;
if (!isObjectOrArray) {
lref = Evaluate(assignmentTarget).Value as ReferenceRecord;
}
let v: unknown;
if (element.type !== "RestElement") {
const { done, value: nextValue } = iteratorRecord.next();
const value = done ? undefined : nextValue;
if (element.type === "AssignmentPattern" && value === undefined) {
// Todo(steve): check IsAnonymousFunctionDefinition(Initializer)
const defaultValue = Evaluate(element.right);
v = GetValue(defaultValue);
} else {
v = value;
}
} else {
// RestElement
v = [];
let n = 0;
// eslint-disable-next-line no-constant-condition
while (true) {
const { done, value: nextValue } = iteratorRecord.next();
if (done) {
break;
}
(v as unknown[])[n] = nextValue;
n++;
}
}
if (isObjectOrArray) {
status = DestructuringAssignmentEvaluation(assignmentTarget, v);
} else {
status = PutValue(lref, v);
}
}
return status;
}
// Object expressions.
// https://tc39.es/ecma262/#sec-evaluate-property-access-with-expression-key
function EvaluatePropertyAccessWithExpressionKey(
baseValue: Record<PropertyKey, unknown>,
expression: Expression,
strict: boolean
): ReferenceRecord {
const propertyNameReference = Evaluate(expression);
const propertyNameValue = GetValue(propertyNameReference);
const propertyKey = ToPropertyKey(propertyNameValue);
return new ReferenceRecord(baseValue, propertyKey, strict);
}
// https://tc39.es/ecma262/#sec-evaluate-property-access-with-identifier-key
function EvaluatePropertyAccessWithIdentifierKey(
baseValue: Record<PropertyKey, unknown>,
identifier: Identifier,
strict: boolean
): ReferenceRecord {
const propertyNameString = identifier.name;
return new ReferenceRecord(baseValue, propertyNameString, strict);
}
// Block statements.
// https://tc39.es/ecma262/#sec-blockdeclarationinstantiation
function BlockDeclarationInstantiation(
code: Statement[] | SwitchCase[],
env: EnvironmentRecord
): void {
const declarations = collectScopedDeclarations(code, {
var: false,
topLevel: false,
});
for (const d of declarations) {
const IsConstantDeclaration =
d.type === "VariableDeclaration" && d.kind === "const";
for (const dn of collectBoundNames(d)) {
if (IsConstantDeclaration) {
env.CreateImmutableBinding(dn, true);
} else {
env.CreateMutableBinding(dn, false);
}
}
if (d.type === "FunctionDeclaration") {
const [fn] = collectBoundNames(d);
const fo = InstantiateFunctionObject(d, env);
env.InitializeBinding(fn, fo);
}
}
}
// Function declarations and expressions.
// https://tc39.es/ecma262/#sec-evaluatecall
function EvaluateCall(
func: SimpleFunction,
ref: ReferenceRecord,
args: CallExpression["arguments"] | TemplateLiteral,
callee: CallExpression["callee"]
): CompletionRecord {
let thisValue;
if (ref instanceof ReferenceRecord) {
if (IsPropertyReference(ref)) {
thisValue = ref.Base;
}
}
const argList = ArgumentListEvaluation(args);
if (typeof func !== "function") {
const funcName = codeSource.substring(callee.start, callee.end);
throw new TypeError(`${funcName} is not a function`);
}
const result = func.apply(thisValue, argList);
sanitize(result);
return NormalCompletion(result);
}
// https://tc39.es/ecma262/#sec-evaluatenew
function EvaluateNew(
constructExpr: CallExpression["callee"],
args: NewExpression["arguments"]
): CompletionRecord {
const ref = Evaluate(constructExpr);
const constructor = GetValue(ref) as new (...args: unknown[]) => unknown;
const argList = ArgumentListEvaluation(args);
if (
typeof constructor !== "function" ||
(constructor as unknown as FunctionObject)[IsConstructor] === false
) {
const constructorName = codeSource.substring(
constructExpr.start,
constructExpr.end
);
throw new TypeError(`${constructorName} is not a constructor`);
}
if (!isAllowedConstructor(constructor)) {
const constructorName = codeSource.substring(
constructExpr.start,
constructExpr.end
);
throw new TypeError(`${constructorName} is not an allowed constructor`);
}
return NormalCompletion(new constructor(...argList));
}
// https://tc39.es/ecma262/#sec-runtime-semantics-argumentlistevaluation
function ArgumentListEvaluation(
args: CallExpression["arguments"] | TemplateLiteral
): unknown[] {
const array: unknown[] = [];
if (Array.isArray(args)) {
for (const arg of args) {
if (arg.type === "SpreadElement") {
const spreadValues = GetValue(Evaluate(arg.argument)) as unknown[];
array.push(...spreadValues);
} else {
array.push(GetValue(Evaluate(arg)));
}
}
} else {
array.push(GetTemplateObject(args));
for (const expr of args.expressions) {
array.push(GetValue(Evaluate(expr)));
}
}
return array;
}
// https://tc39.es/ecma262/#sec-ecmascript-function-objects-call-thisargument-argumentslist
function CallFunction(
closure: FunctionObject,
args: Iterable<unknown>
): unknown {
hooks.beforeCall?.(closure[SourceNode]);
PrepareForOrdinaryCall(closure);
const result = OrdinaryCallEvaluateBody(closure, args);
executionContextStack.pop();
if (result.Type === "return") {
return result.Value;
}
return undefined;
}
// https://tc39.es/ecma262/#sec-prepareforordinarycall
function PrepareForOrdinaryCall(F: FunctionObject): ExecutionContext {
const calleeContext = new ExecutionContext();
calleeContext.Function = F;
const localEnv = new FunctionEnvironment(F[Environment]);
calleeContext.VariableEnvironment = localEnv;
calleeContext.LexicalEnvironment = localEnv;
executionContextStack.push(calleeContext);
return calleeContext;
}
// https://tc39.es/ecma262/#sec-ordinarycallevaluatebody
function OrdinaryCallEvaluateBody(
F: FunctionObject,
args: Iterable<unknown>
): CompletionRecord {
return EvaluateFunctionBody(F[ECMAScriptCode], F, args);
}
// https://tc39.es/ecma262/#sec-runtime-semantics-evaluatefunctionbody
function EvaluateFunctionBody(
body: Statement[] | Expression,
F: FunctionObject,
args: Iterable<unknown>
): CompletionRecord {
FunctionDeclarationInstantiation(F, args);
if (Array.isArray(body)) {
return EvaluateStatementList(body);
}
return new CompletionRecord("return", GetValue(Evaluate(body)));
}
// https://tc39.es/ecma262/#sec-block-runtime-semantics-evaluation
function EvaluateStatementList(statements: Statement[]): CompletionRecord {
let result = NormalCompletion(Empty);
for (const stmt of statements) {
const s = Evaluate(stmt);
if (s.Type !== "normal") {
return s;
}
result = UpdateEmpty(result, s.Value);
}
return result;
}
// https://tc39.es/ecma262/#sec-functiondeclarationinstantiation
function FunctionDeclarationInstantiation(
func: FunctionObject,
args: Iterable<unknown>
): void {
const calleeContext = getRunningContext();
const code = func[ECMAScriptCode] as BlockStatement | Expression;
const formals = func[FormalParameters] as FunctionDeclaration["params"];
const parameterNames = collectBoundNames(formals);
const hasParameterExpressions = containsExpression(formals);
const varDeclarations = collectScopedDeclarations(code, {
var: true,
topLevel: true,
});
const varNames = collectBoundNames(varDeclarations);
// `functionNames` ∈ `varNames`
// `functionsToInitialize` ≈ `functionNames`
const functionNames: string[] = [];
const functionsToInitialize: FunctionDeclaration[] = [];
for (let i = varDeclarations.length - 1; i >= 0; i--) {
const d = varDeclarations[i];
if (d.type === "FunctionDeclaration") {
ThrowIfFunctionIsInvalid(d);
const [fn] = collectBoundNames(d);
if (!functionNames.includes(fn)) {
functionNames.unshift(fn);
functionsToInitialize.unshift(d);
}
} else if (rules?.noVar) {
throw new SyntaxError(
"Var declaration is not recommended, use `let` or `const` instead"
);
}
}
const env = calleeContext.LexicalEnvironment;
for (const paramName of parameterNames) {
// In strict mode, it's guaranteed no duplicate params exist.
env.CreateMutableBinding(paramName, false);
}
const iteratorRecord = CreateListIteratorRecord(args);
IteratorBindingInitialization(formals, iteratorRecord, env);
let varEnv: EnvironmentRecord;
if (!hasParameterExpressions) {
// NOTE: Only a single Environment Record is needed for the parameters
// and top-level vars.
// `varNames` are unique.
for (const n of varNames) {
if (!parameterNames.includes(n)) {
env.CreateMutableBinding(n, false);
env.InitializeBinding(n, undefined);
}
}
varEnv = env;
} else {
// NOTE: A separate Environment Record is needed to ensure that closures
// created by expressions in the formal parameter list do not have
// visibility of declarations in the function body.
varEnv = new DeclarativeEnvironment(env);
calleeContext.VariableEnvironment = varEnv;
// `varNames` are unique.
for (const n of varNames) {
varEnv.CreateMutableBinding(n, false);
let initialValue: unknown;
if (parameterNames.includes(n) && !functionNames.includes(n)) {
initialValue = env.GetBindingValue(n, false);
}
varEnv.InitializeBinding(n, initialValue);
// NOTE: A var with the same name as a formal parameter initially has
// the same value as the corresponding initialized parameter.
}
}
const lexEnv = varEnv;
calleeContext.LexicalEnvironment = lexEnv;
const lexDeclarations = collectScopedDeclarations(code, {
var: false,
topLevel: true,
});
for (const d of lexDeclarations) {
for (const dn of collectBoundNames(d)) {
// Only lexical VariableDeclaration here in top-level.
if ((d as VariableDeclaration).kind === "const") {
lexEnv.CreateImmutableBinding(dn, true);
} else {
lexEnv.CreateMutableBinding(dn, false);
}
}
}
for (const f of functionsToInitialize) {
const [fn] = collectBoundNames(f);
const fo = InstantiateFunctionObject(f, lexEnv);
varEnv.SetMutableBinding(fn, fo, false);
}
}
// https://tc39.es/ecma262/#sec-runtime-semantics-instantiatefunctionobject
function InstantiateFunctionObject(
func: FunctionDeclaration,
scope: EnvironmentRecord
): FunctionObject {
return OrdinaryFunctionCreate(func, scope, true);
}
// https://tc39.es/ecma262/#sec-runtime-semantics-instantiateordinaryfunctionexpression
function InstantiateOrdinaryFunctionExpression(
functionExpression: FunctionExpression
): FunctionObject {
const scope = getRunningContext().LexicalEnvironment;
if (functionExpression.id) {
const name = functionExpression.id.name;
const funcEnv = new DeclarativeEnvironment(scope);
funcEnv.CreateImmutableBinding(name, false);
const closure = OrdinaryFunctionCreate(
functionExpression,
// functionExpression.params,
// functionExpression.body,
funcEnv,
true
);
funcEnv.InitializeBinding(name, closure);
return closure;
} else {
const closure = OrdinaryFunctionCreate(functionExpression, scope, true);
return closure;
}
}
// https://tc39.es/ecma262/#sec-runtime-semantics-instantiatearrowfunctionexpression
function InstantiateArrowFunctionExpression(
arrowFunction: ArrowFunctionExpression
): FunctionObject {
const scope = getRunningContext().LexicalEnvironment;
const closure = OrdinaryFunctionCreate(arrowFunction, scope, false);
return closure;
}
// https://tc39.es/ecma262/#sec-ordinaryfunctioncreate
function OrdinaryFunctionCreate(
sourceNode:
| FunctionDeclaration
| FunctionExpression
| ArrowFunctionExpression,
// parameterList: FunctionDeclaration["params"],
// body: BlockStatement | Expression,
scope: EnvironmentRecord,
isConstructor: boolean
): FunctionObject {
const F = function () {
// eslint-disable-next-line prefer-rest-params
return CallFunction(F, arguments);
} as FunctionObject;
Object.defineProperties(F, {
[SourceNode]: {
value: sourceNode,
},
[FormalParameters]: {
value: sourceNode.params,
},
[ECMAScriptCode]: {
value:
sourceNode.body.type === "BlockStatement"
? sourceNode.body.body
: sourceNode.body,
},
[Environment]: {
value: scope,
},
[IsConstructor]: {
value: isConstructor,
},
});
return F;
}
// Patterns initialization.
// https://tc39.es/ecma262/#sec-runtime-semantics-bindinginitialization
function BindingInitialization(
node: EstreeLVal,
value: unknown,
environment: EnvironmentRecord
): CompletionRecord {
switch (node.type) {
case "Identifier":
return InitializeBoundName(node.name, value, environment);
case "ObjectPattern":
RequireObjectCoercible(value);
return PropertyBindingInitialization(
(node as EstreeObjectPattern).properties,
value,
environment
);
case "ArrayPattern": {
const iteratorRecord = CreateListIteratorRecord(
value as Iterable<unknown>
);
return IteratorBindingInitialization(
node.elements,
iteratorRecord,
environment
);
}
}
}
// https://tc39.es/ecma262/#sec-destructuring-binding-patterns-runtime-semantics-propertybindinginitialization
function PropertyBindingInitialization(
properties: (EstreeProperty | RestElement)[],
value: unknown,
environment: EnvironmentRecord
): CompletionRecord {
const excludedNames = new Set<PropertyKey>();
for (const prop of properties) {
if (prop.type === "RestElement") {
return RestBindingInitialization(
prop,
value,
environment,
excludedNames
);
}
if (!prop.computed && prop.key.type === "Identifier") {
KeyedBindingInitialization(
prop.value as EstreeLVal,
value,
environment,
prop.key.name
);
excludedNames.add(prop.key.name);
} else {
const P = EvaluateComputedPropertyName(prop.key);
KeyedBindingInitialization(
prop.value as EstreeLVal,
value,
environment,
P
);
excludedNames.add(P);
}
}
return NormalCompletion(Empty);
}
// https://tc39.es/ecma262/#prod-ComputedPropertyName
function EvaluateComputedPropertyName(node: Expression): PropertyKey {
const propName = GetValue(Evaluate(node));
return ToPropertyKey(propName);
}
// https://tc39.es/ecma262/#sec-destructuring-binding-patterns-runtime-semantics-restbindinginitialization
function RestBindingInitialization(
restProperty: RestElement,
value: unknown,
environment: EnvironmentRecord,
excludedNames: Set<PropertyKey>
): CompletionRecord {
const lhs = ResolveBinding(
(restProperty.argument as Identifier).name,
environment
);
const restObj = CopyDataProperties({}, value, excludedNames);
if (!environment) {
return PutValue(lhs, restObj);
}
return InitializeReferencedBinding(lhs, restObj);
}
// https://tc39.es/ecma262/#sec-runtime-semantics-iteratorbindinginitialization
function IteratorBindingInitialization(
elements: PatternLike[],
iteratorRecord: Iterator<unknown>,
environment: EnvironmentRecord
): CompletionRecord {
if (elements.length === 0) {
return NormalCompletion(Empty);
}
let result;
for (const node of elements) {
if (!node) {
// Elision element.
iteratorRecord.next();
result = NormalCompletion(Empty);
} else if (node.type === "RestElement") {
// Rest element.
if (node.argument.type === "Identifier") {
const lhs = ResolveBinding(node.argument.name, environment);
const A: unknown[] = [];
let n = 0;
// eslint-disable-next-line no-constant-condition
while (true) {
const { done, value } = iteratorRecord.next();
if (done) {
result = environment
? InitializeReferencedBinding(lhs, A)
: PutValue(lhs, A);
break;
}
A[n] = value;
n++;
}
} else {
const A: unknown[] = [];
let n = 0;
// eslint-disable-next-line no-constant-condition
while (true) {
const { done, value } = iteratorRecord.next();
if (done) {
result = BindingInitialization(node.argument, A, environment);
break;
}
A[n] = value;
n++;
}
}
} else {
// Normal element.
const bindingElement =
node.type === "AssignmentPattern" ? node.left : node;
switch (bindingElement.type) {
case "ObjectPattern":
case "ArrayPattern": {
let v: unknown;
const { done, value } = iteratorRecord.next();
if (!done) {
v = value;
}
if (node.type === "AssignmentPattern" && v === undefined) {
const defaultValue = Evaluate(node.right);
v = GetValue(defaultValue);
}
result = BindingInitialization(bindingElement, v, environment);
break;
}
case "Identifier": {
const bindingId = bindingElement.name;
const lhs = ResolveBinding(bindingId, environment);
let v: unknown;
const { done, value } = iteratorRecord.next();
if (!done) {
v = value;
}
if (node.type === "AssignmentPattern" && v === undefined) {
// IsAnonymousFunctionDefinition(Initializer)
const defaultValue = Evaluate(node.right);
v = GetValue(defaultValue);
}
result = environment
? InitializeReferencedBinding(lhs, v)
: PutValue(lhs, v);
break;
}
}
}
}
return result;
}
// https://tc39.es/ecma262/#sec-runtime-semantics-keyedbindinginitialization
function KeyedBindingInitialization(
node: EstreeLVal,
value: unknown,
environment: EnvironmentRecord,
propertyName: PropertyKey
): CompletionRecord {
const isIdentifier =
node.type === "Identifier" ||
(node.type === "AssignmentPattern" && node.left.type === "Identifier");
if (isIdentifier) {
const bindingId =
node.type === "Identifier" ? node.name : (node.left as Identifier).name;
const lhs = ResolveBinding(bindingId, environment);
let v = GetV(value, propertyName);
if (node.type === "AssignmentPattern" && v === undefined) {
// If IsAnonymousFunctionDefinition(Initializer)
const defaultValue = Evaluate(node.right);
v = GetValue(defaultValue);
}
if (!environment) {
return PutValue(lhs, v);
}
return InitializeReferencedBinding(lhs, v);
}
let v = GetV(value, propertyName);
if (node.type === "AssignmentPattern" && v === undefined) {
const defaultValue = Evaluate(node.right);
v = GetValue(defaultValue);
}
return BindingInitialization(
node.type === "AssignmentPattern" ? node.left : node,
v,
environment
);
}
// https://tc39.es/ecma262/#sec-initializeboundname
function InitializeBoundName(
name: string,
value: unknown,
environment?: EnvironmentRecord
): CompletionRecord {
// Assert: environment is always present.
environment.InitializeBinding(name, value);
return NormalCompletion(Empty);
}
function ThrowIfFunctionIsInvalid(
func: FunctionDeclaration | FunctionExpression | ArrowFunctionExpression
): void {
if (func.async || func.generator) {
throw new SyntaxError(
`${func.async ? "Async" : "Generator"} function is not allowed`
);
}
if (expressionOnly && !(func as ArrowFunctionExpression).expression) {
throw new SyntaxError(
"Only an `Expression` is allowed in `ArrowFunctionExpression`'s body"
);
}
}
if (expressionOnly) {
return GetValue(Evaluate(rootAst));
}
hooks.beforeEvaluate?.(rootAst);
ThrowIfFunctionIsInvalid(rootAst);
const [fn] = collectBoundNames(rootAst);
// Create an immutable binding for the root function.
rootEnv.CreateImmutableBinding(fn, true);
const fo = InstantiateFunctionObject(rootAst, rootEnv);
rootEnv.InitializeBinding(fn, fo);
return fo;
}
