import { ILogEntry, ILogFilterOptions, LogFilter } from "@spinajs/log-common";
/**
 * Options for {@link MatchFilter}.
 */
export interface IMatchFilterOptions extends ILogFilterOptions {
    /** Regex source tested against the chosen field. Required. */
    pattern: string;
    /** Variable field to test. Default "message". */
    field?: string;
    /** "keep" ( default ) keeps on match, drops otherwise; "drop" drops on match. */
    mode?: "keep" | "drop";
    /** RegExp flags ( eg. "i" ). */
    flags?: string;
}
/**
 * Regex keep/drop filter. Builds a RegExp from `pattern`/`flags` and tests it
 * against `String(entry.Variables[field])` ( field defaults to "message" ).
 * In "keep" mode the entry is kept only on a match; in "drop" mode it is
 * dropped on a match. An invalid pattern degrades to a no-op ( pass-through )
 * and warns ONCE so a bad config never silently swallows or drops everything.
 */
export declare class MatchFilter extends LogFilter {
    protected regex: RegExp | null;
    protected field: string;
    protected mode: "keep" | "drop";
    protected warned: boolean;
    constructor(options?: IMatchFilterOptions);
    apply(entry: ILogEntry): ILogEntry | null;
}
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