/**
 * ABAC Policy Decision Point (PDP) Engine
 *
 * This is the core engine that evaluates ABAC policies and makes authorization decisions
 * based on subject, resource, action, and environment attributes.
 */
import { ABACAccessLog, ABACDecision, ABACEngineConfig, ABACPolicy, ABACRequest, AttributeProvider, ConditionFunction, EvaluationMetrics } from './types';
/**
 * Main ABAC Engine implementing Policy Decision Point (PDP)
 */
export declare class ABACEngine {
    private config;
    private logger;
    private functionRegistry;
    private auditService;
    private metricsCollector;
    private attributeResolver;
    private policyEvaluator;
    constructor(config: ABACEngineConfig);
    /**
     * Main evaluation method - Policy Decision Point (PDP)
     */
    evaluate(request: ABACRequest, policies: ABACPolicy[]): Promise<ABACDecision>;
    /**
     * Combine policy results using the specified combining algorithm
     */
    private combineResults;
    /**
     * Validate the access request
     */
    private validateRequest;
    /**
     * Generate unique request ID
     */
    private generateRequestId;
    /**
     * Public methods for engine management
     */
    getMetrics(): EvaluationMetrics;
    getAuditLogs(limit?: number): ABACAccessLog[];
    clearAuditLogs(): void;
    /**
     * Register a custom function for use in conditions
     */
    registerFunction(name: string, fn: ConditionFunction): void;
    /**
     * Add an attribute provider
     */
    addAttributeProvider(provider: AttributeProvider): void;
    /**
     * Remove an attribute provider
     */
    removeAttributeProvider(key: string): void;
}
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