/**
 * @fileoverview Keyword ranking for Census variables: whole-word matching on label and concept,
 * an all-terms filter with a most-terms fallback, and one sort-key order with no weights.
 * @module services/variable-cache/variable-search
 */
import type { CensusVariable } from './types.js';
/** Result of ranking a variable set against a query. */
export interface VariableSearchResult {
    /**
     * Distinct query terms the returned variables contain — every term, unless no variable held
     * them all and the search fell back to the variables that contain the most.
     */
    matchedTermCount: number;
    /** Distinct words in the query. Zero when the query holds no letters or digits. */
    termCount: number;
    /** Variables in the returned tier, before any limit. */
    totalMatches: number;
    /** Matching variables in rank order, cut to the limit. */
    variables: CensusVariable[];
}
/**
 * Rank `variables` against `query`.
 *
 * A term matches a whole word of the label or of the concept. A variable without a concept — a
 * column shared across tables, whose concept joins every table's — matches on its label alone. A
 * margin of error matches on its estimate's label: its own opens with `Margin of Error!!`, and
 * those three words would otherwise rank it alone above its estimate whenever the query holds one
 * of them ("median value of") that the estimate does not.
 * A result contains every distinct term; when no variable does, the result is the variables that
 * contain the most terms, and `matchedTermCount` says how many that was.
 *
 * Results sort on four keys in order: where the query phrase appears (see `Placement`), then
 * fewer `!!` segments in the label, then a shorter concept, then the code. The last key puts an
 * estimate ahead of its tied margin of error, since `…E` sorts before `…M`.
 */
export declare function rankVariables(variables: ReadonlyMap<string, CensusVariable>, query: string, limit: number): VariableSearchResult;
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