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Faster path for creating union types from filterType

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This commit is contained in:
Anders Hejlsberg 2016-08-12 06:54:51 -07:00
parent f1ea145e05
commit e64675eb85
1 changed files with 22 additions and 14 deletions
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36
src/compiler/checker.ts
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@ -5352,12 +5352,12 @@ namespace ts {
}
}
// We deduplicate the constituent types based on object identity. If the subtypeReduction flag is
// specified we also reduce the constituent type set to only include types that aren't subtypes of
// other types. Subtype reduction is expensive for large union types and is possible only when union
// We sort and deduplicate the constituent types based on object identity. If the subtypeReduction
// flag is specified we also reduce the constituent type set to only include types that aren't subtypes
// of other types. Subtype reduction is expensive for large union types and is possible only when union
// types are known not to circularly reference themselves (as is the case with union types created by
// expression constructs such as array literals and the || and ?: operators). Named types can
// circularly reference themselves and therefore cannot be deduplicated during their declaration.
// circularly reference themselves and therefore cannot be subtype reduced during their declaration.
// For example, "type Item = string | (() => Item" is a named type that circularly references itself.
function getUnionType(types: Type[], subtypeReduction?: boolean, aliasSymbol?: Symbol, aliasTypeArguments?: Type[]): Type {
if (types.length === 0) {
@ -5379,15 +5379,23 @@ namespace ts {
typeSet.containsUndefined ? typeSet.containsNonWideningType ? undefinedType : undefinedWideningType :
neverType;
}
else if (typeSet.length === 1) {
return typeSet[0];
return getUnionTypeFromSortedList(typeSet, aliasSymbol, aliasTypeArguments);
}
// This function assumes the constituent type list is sorted and deduplicated.
function getUnionTypeFromSortedList(types: Type[], aliasSymbol?: Symbol, aliasTypeArguments?: Type[]): Type {
if (types.length === 0) {
return neverType;
}
const id = getTypeListId(typeSet);
if (types.length === 1) {
return types[0];
}
const id = getTypeListId(types);
let type = unionTypes[id];
if (!type) {
const propagatedFlags = getPropagatingFlagsOfTypes(typeSet, /*excludeKinds*/ TypeFlags.Nullable);
const propagatedFlags = getPropagatingFlagsOfTypes(types, /*excludeKinds*/ TypeFlags.Nullable);
type = unionTypes[id] = <UnionType>createObjectType(TypeFlags.Union | propagatedFlags);
type.types = typeSet;
type.types = types;
type.aliasSymbol = aliasSymbol;
type.aliasTypeArguments = aliasTypeArguments;
}
@ -8168,12 +8176,12 @@ namespace ts {
}
function filterType(type: Type, f: (t: Type) => boolean): Type {
if (!(type.flags & TypeFlags.Union)) {
return f(type) ? type : neverType;
if (type.flags & TypeFlags.Union) {
const types = (<UnionType>type).types;
const filtered = filter(types, f);
return filtered === types ? type : getUnionTypeFromSortedList(filtered);
}
const types = (<UnionType>type).types;
const filtered = filter(types, f);
return filtered === types ? type : getUnionType(filtered);
return f(type) ? type : neverType;
}
function isIncomplete(flowType: FlowType) {