fix: consistently use NeverType (#1367)

index.ts

@@ -22,7 +22,7 @@ export * from "./src/Utils/isHidden";
 export * from "./src/Utils/modifiers";
 export * from "./src/Utils/narrowType";
 export * from "./src/Utils/nodeKey";
-export * from "./src/Utils/notUndefined";
+export * from "./src/Utils/notNever";
 export * from "./src/Utils/preserveAnnotation";
 export * from "./src/Utils/removeUndefined";
 export * from "./src/Utils/removeUnreachable";

src/ChainNodeParser.ts

@@ -7,7 +7,7 @@ import { BaseType } from "./Type/BaseType";
 import { ReferenceType } from "./Type/ReferenceType";
 
 export class ChainNodeParser implements SubNodeParser, MutableParser {
-    protected readonly typeCaches = new WeakMap<ts.Node, Map<string, BaseType | undefined>>();
+    protected readonly typeCaches = new WeakMap<ts.Node, Map<string, BaseType>>();
 
     public constructor(protected typeChecker: ts.TypeChecker, protected nodeParsers: SubNodeParser[]) {}
 
@@ -20,10 +20,10 @@ export class ChainNodeParser implements SubNodeParser, MutableParser {
         return this.nodeParsers.some((nodeParser) => nodeParser.supportsNode(node));
     }
 
-    public createType(node: ts.Node, context: Context, reference?: ReferenceType): BaseType | undefined {
+    public createType(node: ts.Node, context: Context, reference?: ReferenceType): BaseType {
         let typeCache = this.typeCaches.get(node);
         if (typeCache == null) {
-            typeCache = new Map<string, BaseType | undefined>();
+            typeCache = new Map<string, BaseType>();
             this.typeCaches.set(node, typeCache);
         }
         const contextCacheKey = context.getCacheKey();

src/CircularReferenceNodeParser.ts

@@ -6,14 +6,14 @@ import { ReferenceType } from "./Type/ReferenceType";
 import { getKey } from "./Utils/nodeKey";
 
 export class CircularReferenceNodeParser implements SubNodeParser {
-    protected circular = new Map<string, BaseType>();
+    protected circular: Map<string, BaseType> = new Map();
 
     public constructor(protected childNodeParser: SubNodeParser) {}
 
     public supportsNode(node: ts.Node): boolean {
         return this.childNodeParser.supportsNode(node);
     }
-    public createType(node: ts.Node, context: Context): BaseType | undefined {
+    public createType(node: ts.Node, context: Context): BaseType {
         const key = getKey(node, context);
         if (this.circular.has(key)) {
             return this.circular.get(key)!;

src/CircularReferenceTypeFormatter.ts

@@ -4,8 +4,8 @@ import { BaseType } from "./Type/BaseType";
 import { uniqueArray } from "./Utils/uniqueArray";
 
 export class CircularReferenceTypeFormatter implements SubTypeFormatter {
-    protected definition = new Map<BaseType, Definition>();
-    protected children = new Map<BaseType, BaseType[]>();
+    protected definition: Map<BaseType, Definition> = new Map();
+    protected children: Map<BaseType, BaseType[]> = new Map();
 
     public constructor(protected childTypeFormatter: SubTypeFormatter) {}
 

src/Error/UnknownTypeError.ts

@@ -2,11 +2,11 @@ import { BaseType } from "../Type/BaseType";
 import { BaseError } from "./BaseError";
 
 export class UnknownTypeError extends BaseError {
-    public constructor(private type: BaseType | undefined) {
-        super(`Unknown type "${type ? type.getId() : undefined}"`);
+    public constructor(private type: BaseType) {
+        super(`Unknown type "${type.getId()}"`);
     }
 
-    public getType(): BaseType | undefined {
+    public getType(): BaseType {
         return this.type;
     }
 }

src/ExposeNodeParser.ts

@@ -19,13 +19,9 @@ export class ExposeNodeParser implements SubNodeParser {
         return this.subNodeParser.supportsNode(node);
     }
 
-    public createType(node: ts.Node, context: Context, reference?: ReferenceType): BaseType | undefined {
+    public createType(node: ts.Node, context: Context, reference?: ReferenceType): BaseType {
         const baseType = this.subNodeParser.createType(node, context, reference);
 
-        if (baseType === undefined) {
-            return undefined;
-        }
-
         if (!this.isExportNode(node)) {
             return baseType;
         }

src/NodeParser.ts

@@ -6,16 +6,16 @@ import { getKey } from "./Utils/nodeKey";
 
 export class Context {
     private cacheKey: string | null = null;
-    private arguments: (BaseType | undefined)[] = [];
+    private arguments: BaseType[] = [];
     private parameters: string[] = [];
     private reference?: ts.Node;
-    private defaultArgument = new Map<string, BaseType | undefined>();
+    private defaultArgument = new Map<string, BaseType>();
 
     public constructor(reference?: ts.Node) {
         this.reference = reference;
     }
 
-    public pushArgument(argumentType: BaseType | undefined): void {
+    public pushArgument(argumentType: BaseType): void {
         this.arguments.push(argumentType);
         this.cacheKey = null;
     }
@@ -24,7 +24,7 @@ export class Context {
         this.parameters.push(parameterName);
     }
 
-    public setDefault(parameterName: string, argumentType: BaseType | undefined): void {
+    public setDefault(parameterName: string, argumentType: BaseType): void {
         this.defaultArgument.set(parameterName, argumentType);
     }
 
@@ -38,8 +38,9 @@ export class Context {
         return this.cacheKey;
     }
 
-    public getArgument(parameterName: string): BaseType | undefined {
+    public getArgument(parameterName: string): BaseType {
         const index: number = this.parameters.indexOf(parameterName);
+
         if ((index < 0 || !this.arguments[index]) && this.defaultArgument.has(parameterName)) {
             return this.defaultArgument.get(parameterName)!;
         }
@@ -50,7 +51,7 @@ export class Context {
     public getParameters(): readonly string[] {
         return this.parameters;
     }
-    public getArguments(): readonly (BaseType | undefined)[] {
+    public getArguments(): readonly BaseType[] {
         return this.arguments;
     }
 
@@ -60,5 +61,5 @@ export class Context {
 }
 
 export interface NodeParser {
-    createType(node: ts.Node, context: Context, reference?: ReferenceType): BaseType | undefined;
+    createType(node: ts.Node, context: Context, reference?: ReferenceType): BaseType;
 }

src/NodeParser/AnnotatedNodeParser.ts

@@ -18,7 +18,7 @@ export class AnnotatedNodeParser implements SubNodeParser {
         return this.childNodeParser.supportsNode(node);
     }
 
-    public createType(node: ts.Node, context: Context, reference?: ReferenceType): BaseType | undefined {
+    public createType(node: ts.Node, context: Context, reference?: ReferenceType): BaseType {
         const annotatedNode = this.getAnnotatedNode(node);
         let annotations = this.annotationsReader.getAnnotations(annotatedNode);
         const nullable = this.getNullable(annotatedNode);
@@ -30,10 +30,6 @@ export class AnnotatedNodeParser implements SubNodeParser {
 
         const baseType = this.childNodeParser.createType(node, context, reference);
 
-        if (baseType === undefined) {
-            return undefined;
-        }
-
         // Don't return annotations for lib types such as Exclude.
         if (node.getSourceFile().fileName.match(/[/\\]typescript[/\\]lib[/\\]lib\.[^/\\]+\.d\.ts$/i)) {
             let specialCase = false;

src/NodeParser/ArrayLiteralExpressionNodeParser.ts

@@ -2,7 +2,6 @@ import ts from "typescript";
 import { Context, NodeParser } from "../NodeParser";
 import { SubNodeParser } from "../SubNodeParser";
 import { BaseType } from "../Type/BaseType";
-import { notUndefined } from "../Utils/notUndefined";
 import { TupleType } from "../Type/TupleType";
 
 export class ArrayLiteralExpressionNodeParser implements SubNodeParser {
@@ -12,14 +11,8 @@ export class ArrayLiteralExpressionNodeParser implements SubNodeParser {
         return node.kind === ts.SyntaxKind.ArrayLiteralExpression;
     }
 
-    public createType(node: ts.ArrayLiteralExpression, context: Context): BaseType | undefined {
-        if (node.elements) {
-            const elements = node.elements.map((t) => this.childNodeParser.createType(t, context)).filter(notUndefined);
-
-            return new TupleType(elements);
-        }
-
-        // TODO: implement this?
-        return undefined;
+    public createType(node: ts.ArrayLiteralExpression, context: Context): BaseType {
+        const elements = node.elements.map((t) => this.childNodeParser.createType(t, context));
+        return new TupleType(elements);
     }
 }

src/NodeParser/ArrayNodeParser.ts

@@ -11,11 +11,8 @@ export class ArrayNodeParser implements SubNodeParser {
         return node.kind === ts.SyntaxKind.ArrayType;
     }
 
-    public createType(node: ts.ArrayTypeNode, context: Context): BaseType | undefined {
+    public createType(node: ts.ArrayTypeNode, context: Context): BaseType {
         const type = this.childNodeParser.createType(node.elementType, context);
-        if (type === undefined) {
-            return undefined;
-        }
         return new ArrayType(type);
     }
 }

src/NodeParser/AsExpressionNodeParser.ts

@@ -10,7 +10,7 @@ export class AsExpressionNodeParser implements SubNodeParser {
     public supportsNode(node: ts.AsExpression): boolean {
         return node.kind === ts.SyntaxKind.AsExpression;
     }
-    public createType(node: ts.AsExpression, context: Context): BaseType | undefined {
+    public createType(node: ts.AsExpression, context: Context): BaseType {
         // only implement `as const` for now where we just ignore the as expression
         return this.childNodeParser.createType(node.expression, context);
     }

src/NodeParser/ConditionalTypeNodeParser.ts

@@ -5,9 +5,10 @@ import { BaseType } from "../Type/BaseType";
 import { isAssignableTo } from "../Utils/isAssignableTo";
 import { narrowType } from "../Utils/narrowType";
 import { UnionType } from "../Type/UnionType";
+import { NeverType } from "../Type/NeverType";
 
 class CheckType {
-    constructor(public parameterName: string, public type: BaseType | undefined) {}
+    constructor(public parameterName: string, public type: BaseType) {}
 }
 
 export class ConditionalTypeNodeParser implements SubNodeParser {
@@ -17,7 +18,7 @@ export class ConditionalTypeNodeParser implements SubNodeParser {
         return node.kind === ts.SyntaxKind.ConditionalType;
     }
 
-    public createType(node: ts.ConditionalTypeNode, context: Context): BaseType | undefined {
+    public createType(node: ts.ConditionalTypeNode, context: Context): BaseType {
         const checkType = this.childNodeParser.createType(node.checkType, context);
         const extendsType = this.childNodeParser.createType(node.extendsType, context);
         const checkTypeParameterName = this.getTypeParameterName(node.checkType);
@@ -39,7 +40,7 @@ export class ConditionalTypeNodeParser implements SubNodeParser {
 
         // Follow the relevant branches and return the results from them
         const results: BaseType[] = [];
-        if (trueCheckType !== undefined) {
+        if (!(trueCheckType instanceof NeverType)) {
             const result = this.childNodeParser.createType(
                 node.trueType,
                 this.createSubContext(node, context, new CheckType(checkTypeParameterName, trueCheckType), inferMap)
@@ -48,7 +49,7 @@ export class ConditionalTypeNodeParser implements SubNodeParser {
                 results.push(result);
             }
         }
-        if (falseCheckType !== undefined) {
+        if (!(falseCheckType instanceof NeverType)) {
             const result = this.childNodeParser.createType(
                 node.falseType,
                 this.createSubContext(node, context, new CheckType(checkTypeParameterName, falseCheckType))

src/NodeParser/ExpressionWithTypeArgumentsNodeParser.ts

@@ -9,7 +9,7 @@ export class ExpressionWithTypeArgumentsNodeParser implements SubNodeParser {
     public supportsNode(node: ts.ExpressionWithTypeArguments): boolean {
         return node.kind === ts.SyntaxKind.ExpressionWithTypeArguments;
     }
-    public createType(node: ts.ExpressionWithTypeArguments, context: Context): BaseType | undefined {
+    public createType(node: ts.ExpressionWithTypeArguments, context: Context): BaseType {
         const typeSymbol = this.typeChecker.getSymbolAtLocation(node.expression)!;
         if (typeSymbol.flags & ts.SymbolFlags.Alias) {
             const aliasedSymbol = this.typeChecker.getAliasedSymbol(typeSymbol);

src/NodeParser/HiddenTypeNodeParser.ts

@@ -2,6 +2,7 @@ import ts from "typescript";
 import { Context } from "../NodeParser";
 import { SubNodeParser } from "../SubNodeParser";
 import { BaseType } from "../Type/BaseType";
+import { NeverType } from "../Type/NeverType";
 import { isNodeHidden } from "../Utils/isHidden";
 
 export class HiddenNodeParser implements SubNodeParser {
@@ -11,7 +12,7 @@ export class HiddenNodeParser implements SubNodeParser {
         return isNodeHidden(node);
     }
 
-    public createType(node: ts.KeywordTypeNode, context: Context): BaseType | undefined {
-        return undefined;
+    public createType(_node: ts.KeywordTypeNode, _context: Context): BaseType {
+        return new NeverType();
     }
 }

src/NodeParser/IndexedAccessTypeNodeParser.ts

@@ -4,6 +4,7 @@ import { Context, NodeParser } from "../NodeParser";
 import { SubNodeParser } from "../SubNodeParser";
 import { BaseType } from "../Type/BaseType";
 import { LiteralType } from "../Type/LiteralType";
+import { NeverType } from "../Type/NeverType";
 import { NumberType } from "../Type/NumberType";
 import { StringType } from "../Type/StringType";
 import { TupleType } from "../Type/TupleType";
@@ -18,7 +19,7 @@ export class IndexedAccessTypeNodeParser implements SubNodeParser {
         return node.kind === ts.SyntaxKind.IndexedAccessType;
     }
 
-    private createIndexedType(objectType: ts.TypeNode, context: Context, indexType: BaseType) {
+    private createIndexedType(objectType: ts.TypeNode, context: Context, indexType: BaseType): BaseType | undefined {
         if (ts.isTypeReferenceNode(objectType) && indexType instanceof LiteralType) {
             const declaration = this.typeChecker.getSymbolAtLocation(objectType.typeName)?.declarations?.[0];
 
@@ -40,17 +41,17 @@ export class IndexedAccessTypeNodeParser implements SubNodeParser {
         return undefined;
     }
 
-    public createType(node: ts.IndexedAccessTypeNode, context: Context): BaseType | undefined {
+    public createType(node: ts.IndexedAccessTypeNode, context: Context): BaseType {
         const indexType = derefType(this.childNodeParser.createType(node.indexType, context));
-        const indexedType = indexType && this.createIndexedType(node.objectType, context, indexType);
+        const indexedType = this.createIndexedType(node.objectType, context, indexType);
 
         if (indexedType) {
             return indexedType;
         }
 
         const objectType = derefType(this.childNodeParser.createType(node.objectType, context));
-        if (objectType === undefined || indexType === undefined) {
-            return undefined;
+        if (objectType instanceof NeverType || indexType instanceof NeverType) {
+            return new NeverType();
         }
 
         const indexTypes = indexType instanceof UnionType ? indexType.getTypes() : [indexType];

src/NodeParser/InferTypeNodeParser.ts

@@ -11,7 +11,7 @@ export class InferTypeNodeParser implements SubNodeParser {
         return node.kind === ts.SyntaxKind.InferType;
     }
 
-    public createType(node: ts.InferTypeNode, _context: Context): BaseType | undefined {
+    public createType(node: ts.InferTypeNode, _context: Context): BaseType {
         return new InferType(node.typeParameter.name.escapedText.toString());
     }
 }

src/NodeParser/InterfaceAndClassNodeParser.ts

@@ -3,12 +3,12 @@ import { Context, NodeParser } from "../NodeParser";
 import { SubNodeParser } from "../SubNodeParser";
 import { ArrayType } from "../Type/ArrayType";
 import { BaseType } from "../Type/BaseType";
+import { NeverType } from "../Type/NeverType";
 import { ObjectProperty, ObjectType } from "../Type/ObjectType";
 import { ReferenceType } from "../Type/ReferenceType";
 import { isNodeHidden } from "../Utils/isHidden";
 import { isPublic, isStatic } from "../Utils/modifiers";
 import { getKey } from "../Utils/nodeKey";
-import { notUndefined } from "../Utils/notUndefined";
 
 export class InterfaceAndClassNodeParser implements SubNodeParser {
     public constructor(
@@ -25,7 +25,7 @@ export class InterfaceAndClassNodeParser implements SubNodeParser {
         node: ts.InterfaceDeclaration | ts.ClassDeclaration,
         context: Context,
         reference?: ReferenceType
-    ): BaseType | undefined {
+    ): BaseType {
         if (node.typeParameters?.length) {
             node.typeParameters.forEach((typeParam) => {
                 const nameSymbol = this.typeChecker.getSymbolAtLocation(typeParam.name)!;
@@ -47,7 +47,7 @@ export class InterfaceAndClassNodeParser implements SubNodeParser {
         const properties = this.getProperties(node, context);
 
         if (properties === undefined) {
-            return undefined;
+            return new NeverType();
         }
 
         const additionalProperties = this.getAdditionalProperties(node, context);
@@ -56,11 +56,7 @@ export class InterfaceAndClassNodeParser implements SubNodeParser {
         if (properties.length === 0 && additionalProperties === false) {
             const arrayItemType = this.getArrayItemType(node);
             if (arrayItemType) {
-                const type = this.childNodeParser.createType(arrayItemType, context);
-                if (type === undefined) {
-                    return undefined;
-                }
-                return new ArrayType(type);
+                return new ArrayType(this.childNodeParser.createType(arrayItemType, context));
             }
         }
 
@@ -99,9 +95,7 @@ export class InterfaceAndClassNodeParser implements SubNodeParser {
         return node.heritageClauses.reduce(
             (result: BaseType[], baseType) => [
                 ...result,
-                ...baseType.types
-                    .map((expression) => this.childNodeParser.createType(expression, context))
-                    .filter(notUndefined),
+                ...baseType.types.map((expression) => this.childNodeParser.createType(expression, context)),
             ],
             []
         );
@@ -135,10 +129,10 @@ export class InterfaceAndClassNodeParser implements SubNodeParser {
                     )
             )
             .filter((prop) => {
-                if (prop.isRequired() && prop.getType() === undefined) {
+                if (prop.isRequired() && prop.getType() instanceof NeverType) {
                     hasRequiredNever = true;
                 }
-                return prop.getType() !== undefined;
+                return !(prop.getType() instanceof NeverType);
             });
 
         if (hasRequiredNever) {