export interface FHIRPathExpressionCacheStats {
    hits: number;
    misses: number;
    compileErrors: number;
    hitRate: string;
    size: number;
}
export interface VersionedExpressionCacheOptions<T> {
    maxSize: number;
    keySeparator?: string;
    compile: (expression: string, fhirVersion: 'R4' | 'R5' | 'R6') => T;
    onCompileError?: (expression: string, error: Error) => void;
    errorValue?: (error: Error) => T;
}
export declare class VersionedExpressionCache<T> {
    private readonly options;
    private cache;
    private hits;
    private misses;
    private compileErrors;
    private readonly keySeparator;
    constructor(options: VersionedExpressionCacheOptions<T>);
    getOrCompile(expression: string, fhirVersion?: 'R4' | 'R5' | 'R6'): T;
    getStats(): FHIRPathExpressionCacheStats;
    clear(): void;
    private set;
}
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