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Fix destructuring assignment when assignment target is RHS

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This commit is contained in:
Ron Buckton
2018-01-16 16:58:56 -08:00
parent cd525fb6de
commit 4aca0c8121
8 changed files with 119 additions and 6 deletions
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40
src/compiler/transformers/destructuring.ts
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@@ -70,7 +70,13 @@ namespace ts {
if (value) {
value = visitNode(value, visitor, isExpression);
if (needsValue) {
if (isIdentifier(value) && bindingOrAssignmentElementAssignsToName(node, value.escapedText)) {
// If the right-hand value of the assignment is also an assignment target then
// we need to cache the right-hand value.
value = ensureIdentifier(flattenContext, value, /*reuseIdentifierExpressions*/ false, location);
}
else if (needsValue) {
// If the right-hand value of the destructuring assignment needs to be preserved (as
// is the case when the destructuring assignment is part of a larger expression),
// then we need to cache the right-hand value.
@@ -123,6 +129,27 @@ namespace ts {
}
}
function bindingOrAssignmentElementAssignsToName(element: BindingOrAssignmentElement, escapedName: __String): boolean {
const target = getTargetOfBindingOrAssignmentElement(element);
if (isBindingOrAssignmentPattern(target)) {
return bindingOrAssignmentPatternAssignsToName(target, escapedName);
}
else if (isIdentifier(target)) {
return target.escapedText === escapedName;
}
return false;
}
function bindingOrAssignmentPatternAssignsToName(pattern: BindingOrAssignmentPattern, escapedName: __String): boolean {
const elements = getElementsOfBindingOrAssignmentPattern(pattern);
for (const element of elements) {
if (bindingOrAssignmentElementAssignsToName(element, escapedName)) {
return true;
}
}
return false;
}
/**
* Flattens a VariableDeclaration or ParameterDeclaration to one or more variable declarations.
*
@@ -157,6 +184,17 @@ namespace ts {
createArrayBindingOrAssignmentElement: makeBindingElement,
visitor
};
if (isVariableDeclaration(node)) {
let initializer = getInitializerOfBindingOrAssignmentElement(node);
if (initializer && isIdentifier(initializer) && bindingOrAssignmentElementAssignsToName(node, initializer.escapedText)) {
// If the right-hand value of the assignment is also an assignment target then
// we need to cache the right-hand value.
initializer = ensureIdentifier(flattenContext, initializer, /*reuseIdentifierExpressions*/ false, initializer);
node = updateVariableDeclaration(node, node.name, node.type, initializer);
}
}
flattenBindingOrAssignmentElement(flattenContext, node, rval, node, skipInitializer);
if (pendingExpressions) {
const temp = createTempVariable(/*recordTempVariable*/ undefined);

2
src/compiler/types.ts
View File

@@ -1467,7 +1467,7 @@ namespace ts {
| SpreadAssignment // AssignmentRestProperty
;
export type BindingOrAssignmentElementTarget = BindingOrAssignmentPattern | Expression;
export type BindingOrAssignmentElementTarget = BindingOrAssignmentPattern | Identifier | PropertyAccessExpression | ElementAccessExpression | OmittedExpression;
export type ObjectBindingOrAssignmentPattern
= ObjectBindingPattern