ts-json-schema-generator/src/Utils/derefType.ts

Generate JSON schema from your Typescript sources

import { AliasType } from "../Type/AliasType.js";
import { AnnotatedType } from "../Type/AnnotatedType.js";
import type { BaseType } from "../Type/BaseType.js";
import { DefinitionType } from "../Type/DefinitionType.js";
import { HiddenType } from "../Type/HiddenType.js";
import { LiteralType } from "../Type/LiteralType.js";
import { NeverType } from "../Type/NeverType.js";
import { ReferenceType } from "../Type/ReferenceType.js";
import { UnionType } from "../Type/UnionType.js";

/**
 * Dereference the type as far as possible.
 */
export function derefType(type: BaseType): BaseType {
    if (type instanceof DefinitionType || type instanceof AliasType || type instanceof AnnotatedType) {
        return derefType(type.getType());
    }
    if (type instanceof ReferenceType && type.hasType()) {
        return derefType(type.getType());
    }

    return type;
}

export function derefAnnotatedType(type: BaseType): BaseType {
    if (type instanceof AnnotatedType || type instanceof AliasType) {
        return derefAnnotatedType(type.getType());
    }

    return type;
}

export function isHiddenType(type: BaseType): boolean {
    if (type instanceof HiddenType || type instanceof NeverType) {
        return true;
    } else if (type instanceof DefinitionType || type instanceof AliasType || type instanceof AnnotatedType) {
        return isHiddenType(type.getType());
    }

    return false;
}

/**
 * Recursively checks whether the given type is a union composed entirely of literal types.
 */
export function isDeepLiteralUnion(type: BaseType): boolean {
    const resolved = derefType(type);

    if (resolved instanceof LiteralType) {
        return true;
    }

    if (resolved instanceof UnionType) {
        return resolved.getTypes().every((t) => isDeepLiteralUnion(t));
    }

    return false;
}

export function derefAliasedType(type: BaseType): BaseType {
    if (type instanceof AliasType) {
        return derefAliasedType(type.getType());
    }

    return type;
}