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Merge pull request #24137 from Microsoft/fix23977

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Optimize intersections of unions of unit types
This commit is contained in:
Anders Hejlsberg
2018-05-17 13:15:28 -07:00
committed by GitHub
parent 3fc727b256 027829fbcd
commit 3fc3df3c3a
7 changed files with 355 additions and 4 deletions
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src/compiler/checker.ts
+33 -4
View File
@@ -8400,7 +8400,7 @@ namespace ts {
includes & TypeFlags.Undefined ? includes & TypeFlags.NonWideningType ? undefinedType : undefinedWideningType :
neverType;
}
return getUnionTypeFromSortedList(typeSet, aliasSymbol, aliasTypeArguments);
return getUnionTypeFromSortedList(typeSet, includes & TypeFlags.NotUnit ? 0 : TypeFlags.UnionOfUnitTypes, aliasSymbol, aliasTypeArguments);
}
function getUnionTypePredicate(signatures: ReadonlyArray<Signature>): TypePredicate {
@@ -8440,7 +8440,7 @@ namespace ts {
}
// This function assumes the constituent type list is sorted and deduplicated.
function getUnionTypeFromSortedList(types: Type[], aliasSymbol?: Symbol, aliasTypeArguments?: Type[]): Type {
function getUnionTypeFromSortedList(types: Type[], unionOfUnitTypes: TypeFlags, aliasSymbol?: Symbol, aliasTypeArguments?: Type[]): Type {
if (types.length === 0) {
return neverType;
}
@@ -8451,7 +8451,7 @@ namespace ts {
let type = unionTypes.get(id);
if (!type) {
const propagatedFlags = getPropagatingFlagsOfTypes(types, /*excludeKinds*/ TypeFlags.Nullable);
type = <UnionType>createType(TypeFlags.Union | propagatedFlags);
type = <UnionType>createType(TypeFlags.Union | propagatedFlags | unionOfUnitTypes);
unionTypes.set(id, type);
type.types = types;
/*
@@ -8523,6 +8523,29 @@ namespace ts {
}
}
// When intersecting unions of unit types we can simply intersect based on type identity.
// Here we remove all unions of unit types from the given list and replace them with a
// a single union containing an intersection of the unit types.
function intersectUnionsOfUnitTypes(types: Type[]) {
const unionIndex = findIndex(types, t => (t.flags & TypeFlags.UnionOfUnitTypes) !== 0);
const unionType = <UnionType>types[unionIndex];
let intersection = unionType.types;
let i = types.length - 1;
while (i > unionIndex) {
const t = types[i];
if (t.flags & TypeFlags.UnionOfUnitTypes) {
intersection = filter(intersection, u => containsType((<UnionType>t).types, u));
orderedRemoveItemAt(types, i);
}
i--;
}
if (intersection === unionType.types) {
return false;
}
types[unionIndex] = getUnionTypeFromSortedList(intersection, unionType.flags & TypeFlags.UnionOfUnitTypes);
return true;
}
// We normalize combinations of intersection and union types based on the distributive property of the '&'
// operator. Specifically, because X & (A | B) is equivalent to X & A | X & B, we can transform intersection
// types with union type constituents into equivalent union types with intersection type constituents and
@@ -8557,6 +8580,12 @@ namespace ts {
return typeSet[0];
}
if (includes & TypeFlags.Union) {
if (includes & TypeFlags.UnionOfUnitTypes && intersectUnionsOfUnitTypes(typeSet)) {
// When the intersection creates a reduced set (which might mean that *all* union types have
// disappeared), we restart the operation to get a new set of combined flags. Once we have
// reduced we'll never reduce again, so this occurs at most once.
return getIntersectionType(typeSet, aliasSymbol, aliasTypeArguments);
}
// 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 unionIndex = findIndex(typeSet, t => (t.flags & TypeFlags.Union) !== 0);
@@ -13331,7 +13360,7 @@ namespace ts {
if (type.flags & TypeFlags.Union) {
const types = (<UnionType>type).types;
const filtered = filter(types, f);
return filtered === types ? type : getUnionTypeFromSortedList(filtered);
return filtered === types ? type : getUnionTypeFromSortedList(filtered, type.flags & TypeFlags.UnionOfUnitTypes);
}
return f(type) ? type : neverType;
}
src/compiler/types.ts
+4
View File
@@ -3692,6 +3692,8 @@ namespace ts {
ContainsAnyFunctionType = 1 << 26, // Type is or contains the anyFunctionType
NonPrimitive = 1 << 27, // intrinsic object type
/* @internal */
UnionOfUnitTypes = 1 << 28, // Type is union of unit types
/* @internal */
GenericMappedType = 1 << 29, // Flag used by maybeTypeOfKind
/* @internal */
@@ -3729,6 +3731,8 @@ namespace ts {
Narrowable = Any | StructuredOrInstantiable | StringLike | NumberLike | BooleanLike | ESSymbol | UniqueESSymbol | NonPrimitive,
NotUnionOrUnit = Any | ESSymbol | Object | NonPrimitive,
/* @internal */
NotUnit = Any | String | Number | Boolean | Enum | ESSymbol | Void | Never | StructuredOrInstantiable,
/* @internal */
RequiresWidening = ContainsWideningType | ContainsObjectLiteral,
/* @internal */
PropagatingFlags = ContainsWideningType | ContainsObjectLiteral | ContainsAnyFunctionType,
tests/baselines/reference/intersectionsOfLargeUnions.errors.txt
+35
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@@ -0,0 +1,35 @@
tests/cases/compiler/intersectionsOfLargeUnions.ts(21,15): error TS2536: Type 'T' cannot be used to index type 'HTMLElementTagNameMap'.
tests/cases/compiler/intersectionsOfLargeUnions.ts(21,15): error TS2536: Type 'P' cannot be used to index type 'HTMLElementTagNameMap[T]'.
==== tests/cases/compiler/intersectionsOfLargeUnions.ts (2 errors) ====
// Repro from #23977
export function assertIsElement(node: Node | null): node is Element {
let nodeType = node === null ? null : node.nodeType;
return nodeType === 1;
}
export function assertNodeTagName<
T extends keyof ElementTagNameMap,
U extends ElementTagNameMap[T]>(node: Node | null, tagName: T): node is U {
if (assertIsElement(node)) {
const nodeTagName = node.tagName.toLowerCase();
return nodeTagName === tagName;
}
return false;
}
export function assertNodeProperty<
T extends keyof ElementTagNameMap,
P extends keyof ElementTagNameMap[T],
V extends HTMLElementTagNameMap[T][P]>(node: Node | null, tagName: T, prop: P, value: V) {
~~~~~~~~~~~~~~~~~~~~~~~~
!!! error TS2536: Type 'T' cannot be used to index type 'HTMLElementTagNameMap'.
~~~~~~~~~~~~~~~~~~~~~~~~~~~
!!! error TS2536: Type 'P' cannot be used to index type 'HTMLElementTagNameMap[T]'.
if (assertNodeTagName(node, tagName)) {
node[prop];
}
}
tests/baselines/reference/intersectionsOfLargeUnions.js
+51
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@@ -0,0 +1,51 @@
//// [intersectionsOfLargeUnions.ts]
// Repro from #23977
export function assertIsElement(node: Node | null): node is Element {
let nodeType = node === null ? null : node.nodeType;
return nodeType === 1;
}
export function assertNodeTagName<
T extends keyof ElementTagNameMap,
U extends ElementTagNameMap[T]>(node: Node | null, tagName: T): node is U {
if (assertIsElement(node)) {
const nodeTagName = node.tagName.toLowerCase();
return nodeTagName === tagName;
}
return false;
}
export function assertNodeProperty<
T extends keyof ElementTagNameMap,
P extends keyof ElementTagNameMap[T],
V extends HTMLElementTagNameMap[T][P]>(node: Node | null, tagName: T, prop: P, value: V) {
if (assertNodeTagName(node, tagName)) {
node[prop];
}
}
//// [intersectionsOfLargeUnions.js]
"use strict";
// Repro from #23977
exports.__esModule = true;
function assertIsElement(node) {
var nodeType = node === null ? null : node.nodeType;
return nodeType === 1;
}
exports.assertIsElement = assertIsElement;
function assertNodeTagName(node, tagName) {
if (assertIsElement(node)) {
var nodeTagName = node.tagName.toLowerCase();
return nodeTagName === tagName;
}
return false;
}
exports.assertNodeTagName = assertNodeTagName;
function assertNodeProperty(node, tagName, prop, value) {
if (assertNodeTagName(node, tagName)) {
node[prop];
}
}
exports.assertNodeProperty = assertNodeProperty;
tests/baselines/reference/intersectionsOfLargeUnions.symbols
+95
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@@ -0,0 +1,95 @@
=== tests/cases/compiler/intersectionsOfLargeUnions.ts ===
// Repro from #23977
export function assertIsElement(node: Node | null): node is Element {
>assertIsElement : Symbol(assertIsElement, Decl(intersectionsOfLargeUnions.ts, 0, 0))
>node : Symbol(node, Decl(intersectionsOfLargeUnions.ts, 2, 32))
>Node : Symbol(Node, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
>node : Symbol(node, Decl(intersectionsOfLargeUnions.ts, 2, 32))
>Element : Symbol(Element, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
let nodeType = node === null ? null : node.nodeType;
>nodeType : Symbol(nodeType, Decl(intersectionsOfLargeUnions.ts, 3, 7))
>node : Symbol(node, Decl(intersectionsOfLargeUnions.ts, 2, 32))
>node.nodeType : Symbol(Node.nodeType, Decl(lib.d.ts, --, --))
>node : Symbol(node, Decl(intersectionsOfLargeUnions.ts, 2, 32))
>nodeType : Symbol(Node.nodeType, Decl(lib.d.ts, --, --))
return nodeType === 1;
>nodeType : Symbol(nodeType, Decl(intersectionsOfLargeUnions.ts, 3, 7))
}
export function assertNodeTagName<
>assertNodeTagName : Symbol(assertNodeTagName, Decl(intersectionsOfLargeUnions.ts, 5, 1))
T extends keyof ElementTagNameMap,
>T : Symbol(T, Decl(intersectionsOfLargeUnions.ts, 7, 34))
>ElementTagNameMap : Symbol(ElementTagNameMap, Decl(lib.d.ts, --, --))
U extends ElementTagNameMap[T]>(node: Node | null, tagName: T): node is U {
>U : Symbol(U, Decl(intersectionsOfLargeUnions.ts, 8, 38))
>ElementTagNameMap : Symbol(ElementTagNameMap, Decl(lib.d.ts, --, --))
>T : Symbol(T, Decl(intersectionsOfLargeUnions.ts, 7, 34))
>node : Symbol(node, Decl(intersectionsOfLargeUnions.ts, 9, 36))
>Node : Symbol(Node, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
>tagName : Symbol(tagName, Decl(intersectionsOfLargeUnions.ts, 9, 54))
>T : Symbol(T, Decl(intersectionsOfLargeUnions.ts, 7, 34))
>node : Symbol(node, Decl(intersectionsOfLargeUnions.ts, 9, 36))
>U : Symbol(U, Decl(intersectionsOfLargeUnions.ts, 8, 38))
if (assertIsElement(node)) {
>assertIsElement : Symbol(assertIsElement, Decl(intersectionsOfLargeUnions.ts, 0, 0))
>node : Symbol(node, Decl(intersectionsOfLargeUnions.ts, 9, 36))
const nodeTagName = node.tagName.toLowerCase();
>nodeTagName : Symbol(nodeTagName, Decl(intersectionsOfLargeUnions.ts, 11, 13))
>node.tagName.toLowerCase : Symbol(String.toLowerCase, Decl(lib.d.ts, --, --))
>node.tagName : Symbol(Element.tagName, Decl(lib.d.ts, --, --))
>node : Symbol(node, Decl(intersectionsOfLargeUnions.ts, 9, 36))
>tagName : Symbol(Element.tagName, Decl(lib.d.ts, --, --))
>toLowerCase : Symbol(String.toLowerCase, Decl(lib.d.ts, --, --))
return nodeTagName === tagName;
>nodeTagName : Symbol(nodeTagName, Decl(intersectionsOfLargeUnions.ts, 11, 13))
>tagName : Symbol(tagName, Decl(intersectionsOfLargeUnions.ts, 9, 54))
}
return false;
}
export function assertNodeProperty<
>assertNodeProperty : Symbol(assertNodeProperty, Decl(intersectionsOfLargeUnions.ts, 15, 1))
T extends keyof ElementTagNameMap,
>T : Symbol(T, Decl(intersectionsOfLargeUnions.ts, 17, 35))
>ElementTagNameMap : Symbol(ElementTagNameMap, Decl(lib.d.ts, --, --))
P extends keyof ElementTagNameMap[T],
>P : Symbol(P, Decl(intersectionsOfLargeUnions.ts, 18, 38))
>ElementTagNameMap : Symbol(ElementTagNameMap, Decl(lib.d.ts, --, --))
>T : Symbol(T, Decl(intersectionsOfLargeUnions.ts, 17, 35))
V extends HTMLElementTagNameMap[T][P]>(node: Node | null, tagName: T, prop: P, value: V) {
>V : Symbol(V, Decl(intersectionsOfLargeUnions.ts, 19, 41))
>HTMLElementTagNameMap : Symbol(HTMLElementTagNameMap, Decl(lib.d.ts, --, --))
>T : Symbol(T, Decl(intersectionsOfLargeUnions.ts, 17, 35))
>P : Symbol(P, Decl(intersectionsOfLargeUnions.ts, 18, 38))
>node : Symbol(node, Decl(intersectionsOfLargeUnions.ts, 20, 43))
>Node : Symbol(Node, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
>tagName : Symbol(tagName, Decl(intersectionsOfLargeUnions.ts, 20, 61))
>T : Symbol(T, Decl(intersectionsOfLargeUnions.ts, 17, 35))
>prop : Symbol(prop, Decl(intersectionsOfLargeUnions.ts, 20, 73))
>P : Symbol(P, Decl(intersectionsOfLargeUnions.ts, 18, 38))
>value : Symbol(value, Decl(intersectionsOfLargeUnions.ts, 20, 82))
>V : Symbol(V, Decl(intersectionsOfLargeUnions.ts, 19, 41))
if (assertNodeTagName(node, tagName)) {
>assertNodeTagName : Symbol(assertNodeTagName, Decl(intersectionsOfLargeUnions.ts, 5, 1))
>node : Symbol(node, Decl(intersectionsOfLargeUnions.ts, 20, 43))
>tagName : Symbol(tagName, Decl(intersectionsOfLargeUnions.ts, 20, 61))
node[prop];
>node : Symbol(node, Decl(intersectionsOfLargeUnions.ts, 20, 43))
>prop : Symbol(prop, Decl(intersectionsOfLargeUnions.ts, 20, 73))
}
}
tests/baselines/reference/intersectionsOfLargeUnions.types
+110
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@@ -0,0 +1,110 @@
=== tests/cases/compiler/intersectionsOfLargeUnions.ts ===
// Repro from #23977
export function assertIsElement(node: Node | null): node is Element {
>assertIsElement : (node: Node | null) => node is Element
>node : Node | null
>Node : Node
>null : null
>node : any
>Element : Element
let nodeType = node === null ? null : node.nodeType;
>nodeType : number | null
>node === null ? null : node.nodeType : number | null
>node === null : boolean
>node : Node | null
>null : null
>null : null
>node.nodeType : number
>node : Node
>nodeType : number
return nodeType === 1;
>nodeType === 1 : boolean
>nodeType : number | null
>1 : 1
}
export function assertNodeTagName<
>assertNodeTagName : <T extends "symbol" | "object" | "a" | "abbr" | "acronym" | "address" | "applet" | "area" | "article" | "aside" | "audio" | "b" | "base" | "basefont" | "bdo" | "big" | "blockquote" | "body" | "br" | "button" | "canvas" | "caption" | "center" | "cite" | "code" | "col" | "colgroup" | "data" | "datalist" | "dd" | "del" | "dfn" | "dir" | "div" | "dl" | "dt" | "em" | "embed" | "fieldset" | "figcaption" | "figure" | "font" | "footer" | "form" | "frame" | "frameset" | "h1" | "h2" | "h3" | "h4" | "h5" | "h6" | "head" | "header" | "hgroup" | "hr" | "html" | "i" | "iframe" | "img" | "input" | "ins" | "isindex" | "kbd" | "keygen" | "label" | "legend" | "li" | "link" | "listing" | "map" | "mark" | "marquee" | "menu" | "meta" | "meter" | "nav" | "nextid" | "nobr" | "noframes" | "noscript" | "ol" | "optgroup" | "option" | "output" | "p" | "param" | "picture" | "plaintext" | "pre" | "progress" | "q" | "rt" | "ruby" | "s" | "samp" | "script" | "section" | "select" | "slot" | "small" | "source" | "span" | "strike" | "strong" | "style" | "sub" | "sup" | "table" | "tbody" | "td" | "template" | "textarea" | "tfoot" | "th" | "thead" | "time" | "title" | "tr" | "track" | "tt" | "u" | "ul" | "var" | "video" | "wbr" | "xmp" | "circle" | "clippath" | "defs" | "desc" | "ellipse" | "feblend" | "fecolormatrix" | "fecomponenttransfer" | "fecomposite" | "feconvolvematrix" | "fediffuselighting" | "fedisplacementmap" | "fedistantlight" | "feflood" | "fefunca" | "fefuncb" | "fefuncg" | "fefuncr" | "fegaussianblur" | "feimage" | "femerge" | "femergenode" | "femorphology" | "feoffset" | "fepointlight" | "fespecularlighting" | "fespotlight" | "fetile" | "feturbulence" | "filter" | "foreignobject" | "g" | "image" | "line" | "lineargradient" | "marker" | "mask" | "metadata" | "path" | "pattern" | "polygon" | "polyline" | "radialgradient" | "rect" | "stop" | "svg" | "switch" | "text" | "textpath" | "tspan" | "use" | "view", U extends ElementTagNameMap[T]>(node: Node | null, tagName: T) => node is U
T extends keyof ElementTagNameMap,
>T : T
>ElementTagNameMap : ElementTagNameMap
U extends ElementTagNameMap[T]>(node: Node | null, tagName: T): node is U {
>U : U
>ElementTagNameMap : ElementTagNameMap
>T : T
>node : Node | null
>Node : Node
>null : null
>tagName : T
>T : T
>node : any
>U : U
if (assertIsElement(node)) {
>assertIsElement(node) : boolean
>assertIsElement : (node: Node | null) => node is Element
>node : Node | null
const nodeTagName = node.tagName.toLowerCase();
>nodeTagName : string
>node.tagName.toLowerCase() : string
>node.tagName.toLowerCase : () => string
>node.tagName : string
>node : Element
>tagName : string
>toLowerCase : () => string
return nodeTagName === tagName;
>nodeTagName === tagName : boolean
>nodeTagName : string
>tagName : T
}
return false;
>false : false
}
export function assertNodeProperty<
>assertNodeProperty : <T extends "symbol" | "object" | "a" | "abbr" | "acronym" | "address" | "applet" | "area" | "article" | "aside" | "audio" | "b" | "base" | "basefont" | "bdo" | "big" | "blockquote" | "body" | "br" | "button" | "canvas" | "caption" | "center" | "cite" | "code" | "col" | "colgroup" | "data" | "datalist" | "dd" | "del" | "dfn" | "dir" | "div" | "dl" | "dt" | "em" | "embed" | "fieldset" | "figcaption" | "figure" | "font" | "footer" | "form" | "frame" | "frameset" | "h1" | "h2" | "h3" | "h4" | "h5" | "h6" | "head" | "header" | "hgroup" | "hr" | "html" | "i" | "iframe" | "img" | "input" | "ins" | "isindex" | "kbd" | "keygen" | "label" | "legend" | "li" | "link" | "listing" | "map" | "mark" | "marquee" | "menu" | "meta" | "meter" | "nav" | "nextid" | "nobr" | "noframes" | "noscript" | "ol" | "optgroup" | "option" | "output" | "p" | "param" | "picture" | "plaintext" | "pre" | "progress" | "q" | "rt" | "ruby" | "s" | "samp" | "script" | "section" | "select" | "slot" | "small" | "source" | "span" | "strike" | "strong" | "style" | "sub" | "sup" | "table" | "tbody" | "td" | "template" | "textarea" | "tfoot" | "th" | "thead" | "time" | "title" | "tr" | "track" | "tt" | "u" | "ul" | "var" | "video" | "wbr" | "xmp" | "circle" | "clippath" | "defs" | "desc" | "ellipse" | "feblend" | "fecolormatrix" | "fecomponenttransfer" | "fecomposite" | "feconvolvematrix" | "fediffuselighting" | "fedisplacementmap" | "fedistantlight" | "feflood" | "fefunca" | "fefuncb" | "fefuncg" | "fefuncr" | "fegaussianblur" | "feimage" | "femerge" | "femergenode" | "femorphology" | "feoffset" | "fepointlight" | "fespecularlighting" | "fespotlight" | "fetile" | "feturbulence" | "filter" | "foreignobject" | "g" | "image" | "line" | "lineargradient" | "marker" | "mask" | "metadata" | "path" | "pattern" | "polygon" | "polyline" | "radialgradient" | "rect" | "stop" | "svg" | "switch" | "text" | "textpath" | "tspan" | "use" | "view", P extends keyof ElementTagNameMap[T], V extends HTMLElementTagNameMap[T][P]>(node: Node | null, tagName: T, prop: P, value: V) => void
T extends keyof ElementTagNameMap,
>T : T
>ElementTagNameMap : ElementTagNameMap
P extends keyof ElementTagNameMap[T],
>P : P
>ElementTagNameMap : ElementTagNameMap
>T : T
V extends HTMLElementTagNameMap[T][P]>(node: Node | null, tagName: T, prop: P, value: V) {
>V : V
>HTMLElementTagNameMap : HTMLElementTagNameMap
>T : T
>P : P
>node : Node | null
>Node : Node
>null : null
>tagName : T
>T : T
>prop : P
>P : P
>value : V
>V : V
if (assertNodeTagName(node, tagName)) {
>assertNodeTagName(node, tagName) : boolean
>assertNodeTagName : <T extends "symbol" | "object" | "a" | "abbr" | "acronym" | "address" | "applet" | "area" | "article" | "aside" | "audio" | "b" | "base" | "basefont" | "bdo" | "big" | "blockquote" | "body" | "br" | "button" | "canvas" | "caption" | "center" | "cite" | "code" | "col" | "colgroup" | "data" | "datalist" | "dd" | "del" | "dfn" | "dir" | "div" | "dl" | "dt" | "em" | "embed" | "fieldset" | "figcaption" | "figure" | "font" | "footer" | "form" | "frame" | "frameset" | "h1" | "h2" | "h3" | "h4" | "h5" | "h6" | "head" | "header" | "hgroup" | "hr" | "html" | "i" | "iframe" | "img" | "input" | "ins" | "isindex" | "kbd" | "keygen" | "label" | "legend" | "li" | "link" | "listing" | "map" | "mark" | "marquee" | "menu" | "meta" | "meter" | "nav" | "nextid" | "nobr" | "noframes" | "noscript" | "ol" | "optgroup" | "option" | "output" | "p" | "param" | "picture" | "plaintext" | "pre" | "progress" | "q" | "rt" | "ruby" | "s" | "samp" | "script" | "section" | "select" | "slot" | "small" | "source" | "span" | "strike" | "strong" | "style" | "sub" | "sup" | "table" | "tbody" | "td" | "template" | "textarea" | "tfoot" | "th" | "thead" | "time" | "title" | "tr" | "track" | "tt" | "u" | "ul" | "var" | "video" | "wbr" | "xmp" | "circle" | "clippath" | "defs" | "desc" | "ellipse" | "feblend" | "fecolormatrix" | "fecomponenttransfer" | "fecomposite" | "feconvolvematrix" | "fediffuselighting" | "fedisplacementmap" | "fedistantlight" | "feflood" | "fefunca" | "fefuncb" | "fefuncg" | "fefuncr" | "fegaussianblur" | "feimage" | "femerge" | "femergenode" | "femorphology" | "feoffset" | "fepointlight" | "fespecularlighting" | "fespotlight" | "fetile" | "feturbulence" | "filter" | "foreignobject" | "g" | "image" | "line" | "lineargradient" | "marker" | "mask" | "metadata" | "path" | "pattern" | "polygon" | "polyline" | "radialgradient" | "rect" | "stop" | "svg" | "switch" | "text" | "textpath" | "tspan" | "use" | "view", U extends ElementTagNameMap[T]>(node: Node | null, tagName: T) => node is U
>node : Node | null
>tagName : T
node[prop];
>node[prop] : ElementTagNameMap[T][P]
>node : ElementTagNameMap[T]
>prop : P
}
}
tests/cases/compiler/intersectionsOfLargeUnions.ts
+27
View File
@@ -0,0 +1,27 @@
// @strict: true
// Repro from #23977
export function assertIsElement(node: Node | null): node is Element {
let nodeType = node === null ? null : node.nodeType;
return nodeType === 1;
}
export function assertNodeTagName<
T extends keyof ElementTagNameMap,
U extends ElementTagNameMap[T]>(node: Node | null, tagName: T): node is U {
if (assertIsElement(node)) {
const nodeTagName = node.tagName.toLowerCase();
return nodeTagName === tagName;
}
return false;
}
export function assertNodeProperty<
T extends keyof ElementTagNameMap,
P extends keyof ElementTagNameMap[T],
V extends HTMLElementTagNameMap[T][P]>(node: Node | null, tagName: T, prop: P, value: V) {
if (assertNodeTagName(node, tagName)) {
node[prop];
}
}