import { LogFormatter, LogEntry, JSONFormatterOptions } from '../types';
/**
 * JSON formatter for structured log output
 */
export declare class JSONFormatter implements LogFormatter {
    private prettyPrint;
    private space;
    private includeStack;
    constructor(options?: JSONFormatterOptions);
    format(entry: LogEntry): string;
    /**
     * Handles serialization issues in metadata
     */
    private handleCircularReferences;
}
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