/**
 * SchemaMerger — P2 unified xs:import / xs:include / xs:redefine merge logic
 * ──────────────────────────────────────────────────────────────────────────────
 * Extracted from XsdParser so that merge semantics are independently testable
 * and the XsdParser itself only handles parsing, not merging.
 *
 * Responsibilities:
 *  • Track which schemas have already been merged (dedup by namespace+location).
 *  • Cache parsed sub-schemas by content hash to prevent repeated re-parsing.
 *  • Merge sub-SchemaModels into a parent SchemaModel.
 *  • Apply xs:redefine overrides after the base schema has been merged.
 *
 * This class is consumed internally by XsdParser. It is not part of the public API.
 * @internal
 */
import { SchemaModel } from '../schema/SchemaModel';
import { SchemaLoader } from './XsdParser';
export type SubParser = (src: string, loader?: SchemaLoader) => SchemaModel;
export declare class SchemaMerger {
    private readonly loader;
    /** Set of logical keys (namespace+location) already merged — prevents import cycles. */
    private readonly imported;
    /**
     * Content-addressed parse cache. Key: sha256Short(src).
     * Shared across all SchemaMerger instances that participate in the same
     * top-level parse() call to prevent cascading re-compilation.
     */
    private readonly parseCache;
    constructor(loader: SchemaLoader | undefined, 
    /** Pass in an existing cache to share across sub-parsers. */
    sharedCache?: Map<string, SchemaModel>);
    /** Expose the cache so sub-parsers can share it. */
    get cache(): Map<string, SchemaModel>;
    /**
     * Handle xs:import or xs:include.
     * Returns the merged sub-schema, or null if already imported / no loader.
     */
    handleImport(schemaLocation: string, namespace: string, targetSchema: SchemaModel, subParser: SubParser): SchemaModel | null;
    /**
     * Handle xs:redefine.
     * Merges the base schema first, then applies the override definitions.
     */
    handleRedefine(schemaLocation: string, namespace: string, targetSchema: SchemaModel, subParser: SubParser, applyOverrides: () => void): void;
    /**
     * Parse a sub-schema source, using the content-hash cache to avoid
     * re-parsing the same XSD source within a parse tree.
     */
    private _parse;
    /** Mark a key as already imported (used when XsdParser shares importedNs). */
    markImported(key: string): void;
    hasImported(key: string): boolean;
}
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