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es2021.ts
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91 lines (83 loc) · 4 KB
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/*@internal*/
namespace ts {
export function transformES2021(context: TransformationContext) {
const {
hoistVariableDeclaration,
factory
} = context;
return chainBundle(context, transformSourceFile);
function transformSourceFile(node: SourceFile) {
if (node.isDeclarationFile) {
return node;
}
return visitEachChild(node, visitor, context);
}
function visitor(node: Node): VisitResult<Node> {
if ((node.transformFlags & TransformFlags.ContainsES2021) === 0) {
return node;
}
switch (node.kind) {
case SyntaxKind.BinaryExpression:
const binaryExpression = node as BinaryExpression;
if (isLogicalOrCoalescingAssignmentExpression(binaryExpression)) {
return transformLogicalAssignment(binaryExpression);
}
// falls through
default:
return visitEachChild(node, visitor, context);
}
}
function transformLogicalAssignment(binaryExpression: AssignmentExpression<Token<LogicalOrCoalescingAssignmentOperator>>): VisitResult<Node> {
const operator = binaryExpression.operatorToken;
const nonAssignmentOperator = getNonAssignmentOperatorForCompoundAssignment(operator.kind);
let left = skipParentheses(visitNode(binaryExpression.left, visitor, isLeftHandSideExpression));
let assignmentTarget = left;
const right = skipParentheses(visitNode(binaryExpression.right, visitor, isExpression));
if (isAccessExpression(left)) {
const propertyAccessTargetSimpleCopiable = isSimpleCopiableExpression(left.expression);
const propertyAccessTarget = propertyAccessTargetSimpleCopiable ? left.expression :
factory.createTempVariable(hoistVariableDeclaration);
const propertyAccessTargetAssignment = propertyAccessTargetSimpleCopiable ? left.expression : factory.createAssignment(
propertyAccessTarget,
left.expression
);
if (isPropertyAccessExpression(left)) {
assignmentTarget = factory.createPropertyAccessExpression(
propertyAccessTarget,
left.name
);
left = factory.createPropertyAccessExpression(
propertyAccessTargetAssignment,
left.name
);
}
else {
const elementAccessArgumentSimpleCopiable = isSimpleCopiableExpression(left.argumentExpression);
const elementAccessArgument = elementAccessArgumentSimpleCopiable ? left.argumentExpression :
factory.createTempVariable(hoistVariableDeclaration);
assignmentTarget = factory.createElementAccessExpression(
propertyAccessTarget,
elementAccessArgument
);
left = factory.createElementAccessExpression(
propertyAccessTargetAssignment,
elementAccessArgumentSimpleCopiable ? left.argumentExpression : factory.createAssignment(
elementAccessArgument,
left.argumentExpression
)
);
}
}
return factory.createBinaryExpression(
left,
nonAssignmentOperator,
factory.createParenthesizedExpression(
factory.createAssignment(
assignmentTarget,
right
)
)
);
}
}
}