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Deduplicate intersection types before distributing over union types

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This commit is contained in:
Anders Hejlsberg
2016-11-28 09:34:50 -08:00
parent 88b7d53978
commit 3e1b443d77
1 changed files with 12 additions and 9 deletions
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21
src/compiler/checker.ts
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@@ -5637,6 +5637,7 @@ namespace ts {
containsString?: boolean;
containsNumber?: boolean;
containsStringOrNumberLiteral?: boolean;
unionIndex?: number;
}
function binarySearchTypes(types: Type[], type: Type): number {
@@ -5831,6 +5832,9 @@ namespace ts {
typeSet.containsAny = true;
}
else if (!(type.flags & TypeFlags.Never) && (strictNullChecks || !(type.flags & TypeFlags.Nullable)) && !contains(typeSet, type)) {
if (type.flags & TypeFlags.Union && typeSet.unionIndex === undefined) {
typeSet.unionIndex = typeSet.length;
}
typeSet.push(type);
}
}
@@ -5857,15 +5861,6 @@ namespace ts {
if (types.length === 0) {
return emptyObjectType;
}
for (let i = 0; i < types.length; i++) {
const type = types[i];
if (type.flags & TypeFlags.Union) {
// We are attempting to construct a type of the form X & (A | B) & Y. Transform this into a type of
// the form X & A & Y | X & B & Y and recursively reduce until no union type constituents remain.
return getUnionType(map((<UnionType>type).types, t => getIntersectionType(replaceElement(types, i, t))),
/*subtypeReduction*/ false, aliasSymbol, aliasTypeArguments);
}
}
const typeSet = [] as TypeSet;
addTypesToIntersection(typeSet, types);
if (typeSet.containsAny) {
@@ -5874,6 +5869,14 @@ namespace ts {
if (typeSet.length === 1) {
return typeSet[0];
}
const unionIndex = typeSet.unionIndex;
if (unionIndex !== undefined) {
// We are attempting to construct a type of the form X & (A | B) & Y. Transform this into a type of
// the form X & A & Y | X & B & Y and recursively reduce until no union type constituents remain.
const unionType = <UnionType>typeSet[unionIndex];
return getUnionType(map(unionType.types, t => getIntersectionType(replaceElement(typeSet, unionIndex, t))),
/*subtypeReduction*/ false, aliasSymbol, aliasTypeArguments);
}
const id = getTypeListId(typeSet);
let type = intersectionTypes[id];
if (!type) {