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When calculating spreads, merge empty object into nonempty object to … (#34853)

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* When calculating spreads, merge empty object into nonempty object to produce partial object to reduce complexity

* Actually accept remainder of baselines

* Limit simplification to single prop or partial types
This commit is contained in:
Wesley Wigham
2019-11-22 17:19:17 -08:00
committed by GitHub
parent 58a05f3e87
commit b9689228b5
11 changed files with 1070 additions and 42 deletions
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63
src/compiler/checker.ts
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@@ -12524,6 +12524,61 @@ namespace ts {
return !!(type.flags & TypeFlags.Object) && !isGenericMappedType(type);
}
function isEmptyObjectTypeOrSpreadsIntoEmptyObject(type: Type) {
return isEmptyObjectType(type) || !!(type.flags & (TypeFlags.Null | TypeFlags.Undefined | TypeFlags.BooleanLike | TypeFlags.NumberLike | TypeFlags.BigIntLike | TypeFlags.StringLike | TypeFlags.EnumLike | TypeFlags.NonPrimitive | TypeFlags.Index));
}
function isSinglePropertyAnonymousObjectType(type: Type) {
return !!(type.flags & TypeFlags.Object) &&
!!(getObjectFlags(type) & ObjectFlags.Anonymous) &&
(length(getPropertiesOfType(type)) === 1 || every(getPropertiesOfType(type), p => !!(p.flags & SymbolFlags.Optional)));
}
function tryMergeUnionOfObjectTypeAndEmptyObject(type: UnionType, readonly: boolean): Type | undefined {
if (type.types.length === 2) {
const firstType = type.types[0];
const secondType = type.types[1];
if (every(type.types, isEmptyObjectTypeOrSpreadsIntoEmptyObject)) {
return isEmptyObjectType(firstType) ? firstType : isEmptyObjectType(secondType) ? secondType : emptyObjectType;
}
if (isEmptyObjectTypeOrSpreadsIntoEmptyObject(firstType) && isSinglePropertyAnonymousObjectType(secondType)) {
return getAnonymousPartialType(secondType);
}
if (isEmptyObjectTypeOrSpreadsIntoEmptyObject(secondType) && isSinglePropertyAnonymousObjectType(firstType)) {
return getAnonymousPartialType(firstType);
}
}
function getAnonymousPartialType(type: Type) {
// gets the type as if it had been spread, but where everything in the spread is made optional
const members = createSymbolTable();
for (const prop of getPropertiesOfType(type)) {
if (getDeclarationModifierFlagsFromSymbol(prop) & (ModifierFlags.Private | ModifierFlags.Protected)) {
// do nothing, skip privates
}
else if (isSpreadableProperty(prop)) {
const isSetonlyAccessor = prop.flags & SymbolFlags.SetAccessor && !(prop.flags & SymbolFlags.GetAccessor);
const flags = SymbolFlags.Property | SymbolFlags.Optional;
const result = createSymbol(flags, prop.escapedName, readonly ? CheckFlags.Readonly : 0);
result.type = isSetonlyAccessor ? undefinedType : getTypeOfSymbol(prop);
result.declarations = prop.declarations;
result.nameType = prop.nameType;
result.syntheticOrigin = prop;
members.set(prop.escapedName, result);
}
}
const spread = createAnonymousType(
type.symbol,
members,
emptyArray,
emptyArray,
getIndexInfoOfType(type, IndexKind.String),
getIndexInfoOfType(type, IndexKind.Number));
spread.objectFlags |= ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral;
return spread;
}
}
/**
* Since the source of spread types are object literals, which are not binary,
* this function should be called in a left folding style, with left = previous result of getSpreadType
@@ -12543,9 +12598,17 @@ namespace ts {
return left;
}
if (left.flags & TypeFlags.Union) {
const merged = tryMergeUnionOfObjectTypeAndEmptyObject(left as UnionType, readonly);
if (merged) {
return getSpreadType(merged, right, symbol, objectFlags, readonly);
}
return mapType(left, t => getSpreadType(t, right, symbol, objectFlags, readonly));
}
if (right.flags & TypeFlags.Union) {
const merged = tryMergeUnionOfObjectTypeAndEmptyObject(right as UnionType, readonly);
if (merged) {
return getSpreadType(left, merged, symbol, objectFlags, readonly);
}
return mapType(right, t => getSpreadType(left, t, symbol, objectFlags, readonly));
}
if (right.flags & (TypeFlags.BooleanLike | TypeFlags.NumberLike | TypeFlags.BigIntLike | TypeFlags.StringLike | TypeFlags.EnumLike | TypeFlags.NonPrimitive | TypeFlags.Index)) {