/**
 * @module SourceReader/SourcePositions
 * @author Alan Rodas Bonjour <alanrodas@gmail.com>
 */
import { AbstractSourcePosition } from './AbstractSourcePosition';
import { SourcePosition } from '../SourcePosition';
/**
 * An {@link UnknownSourcePosition} represents an unknown source position,
 * that is, it does not point to any position in any source reader.
 * These positions responds with `true` to the operation
 * {@link SourcePosition.isUnknown | isUnknown}.
 *
 * It is used when a position must be provided, but no one is known, working as
 * a [Null Object Pattern](https://en.wikipedia.org/wiki/Null_object_pattern).
 * Additionally, this class follows the
 * [Singleton Pattern](https://en.wikipedia.org/wiki/Singleton_pattern)
 * using an eager initialization.
 *
 * This class has a single instance, accessible through the
 * {@link UnknownSourcePosition.instance | instance} static field,
 * and cannot be further instantiated.
 */
export declare class UnknownSourcePosition extends AbstractSourcePosition implements SourcePosition {
    /**
     * Returns the single instance of this class.
     */
    static readonly instance: UnknownSourcePosition;
    /**
     * @inheritdoc
     */
    readonly isUnknown: boolean;
    /**
     * Returns an instance of this class.
     * Made private to follow the singleton pattern.
     */
    private constructor();
    /**
     * @inheritdoc
     */
    get isEndOfInput(): boolean;
    /**
     * @inheritdoc
     */
    get isEndOfDocument(): boolean;
    /**
     * @inheritdoc
     */
    get line(): number;
    /**
     * @inheritdoc
     */
    get column(): number;
    /**
     * @inheritdoc
     * @group API: Access
     */
    get regions(): string[];
    /**
     * @inheritdoc
     */
    get documentName(): string;
    /**
     * @inheritdoc
     */
    get fullDocumentContents(): string;
    /**
     * @inheritdoc
     */
    get visibleDocumentContents(): string;
    /**
     * @inheritdoc
     */
    fullContentsFrom(_from: SourcePosition): string;
    /**
     * @inheritdoc
     */
    fullContentsTo(_from: SourcePosition): string;
    /**
     * @inheritdoc
     */
    visibleContentsFrom(_from: SourcePosition): string;
    /**
     * @inheritdoc
     */
    visibleContentsTo(_from: SourcePosition): string;
    /**
     * @inheritdoc
     */
    documentContextBefore(_lines: number): string[];
    /**
     * @inheritdoc
     */
    documentContextAfter(_lines: number): string[];
    /**
     * @inheritdoc
     */
    toString(): string;
}
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