import type { ValidationIssue } from '../types';
import type { StructureDefinition } from '../core/structure-definition-types';
import { StructureDefinitionLoader } from '../core/structure-definition-loader';
import { TypeValidator } from './type-validator';
import { ValueSetValidator } from './valueset-validator';
import { ElementRulesValidator } from './element-rules-validator';
import type { ExtensionValidationContext } from './extension-types';
export type { ExtensionDefinition, ExtensionValidationContext } from './extension-types';
export declare class ExtensionValidator {
    private readonly sdLoader;
    private readonly typeValidator;
    private readonly valueSetValidator;
    private readonly elementRulesValidator;
    private extensionProfileCache;
    /**
     * Cache of sub-extension definitions keyed by parent extension profile URL.
     * Avoids parsing complex-extension snapshots for every nested instance.
     */
    private subExtensionDefinitionsCache;
    /**
     * Remembers whether the loader resolved each extension URL.
     */
    private urlResolvabilityCache;
    /**
     * Bounds malformed or cyclic nested-extension input.
     */
    private readonly maxNestedExtensionDepth;
    constructor(sdLoader: StructureDefinitionLoader, typeValidator: TypeValidator, valueSetValidator: ValueSetValidator, elementRulesValidator: ElementRulesValidator);
    validateExtensions(resource: any, profileSD: StructureDefinition, context: ExtensionValidationContext): Promise<ValidationIssue[]>;
    /**
     * Check whether an extension URL resolves to a loadable StructureDefinition.
     * Results are cached per-validator to avoid hitting the SD loader (and
     * its DB cache / auto-download) for the same URL repeatedly.
     */
    private isExtensionUrlResolvable;
    /**
     * Validate a single extension instance.
     *
     * The optional `depth` argument guards against runaway recursion on
     * pathological input (e.g. an extension array that mutates to reference
     * itself). Each level of nesting increments the counter; once we exceed
     * `maxNestedExtensionDepth` the method returns early with a dedicated
     * diagnostic so callers can see why traversal stopped.
     */
    private validateExtensionInstance;
}
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