/**
 * @license
 * Copyright 2020 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */
import { Connection } from './connection.js';
import type { IConnectionChecker } from './interfaces/i_connection_checker.js';
import type { RenderedConnection } from './rendered_connection.js';
/**
 * Class for connection type checking logic.
 */
export declare class ConnectionChecker implements IConnectionChecker {
    /**
     * Check whether the current connection can connect with the target
     * connection.
     *
     * @param a Connection to check compatibility with.
     * @param b Connection to check compatibility with.
     * @param isDragging True if the connection is being made by dragging a block.
     * @param opt_distance The max allowable distance between the connections for
     *     drag checks.
     * @returns Whether the connection is legal.
     */
    canConnect(a: Connection | null, b: Connection | null, isDragging: boolean, opt_distance?: number): boolean;
    /**
     * Checks whether the current connection can connect with the target
     * connection, and return an error code if there are problems.
     *
     * @param a Connection to check compatibility with.
     * @param b Connection to check compatibility with.
     * @param isDragging True if the connection is being made by dragging a block.
     * @param opt_distance The max allowable distance between the connections for
     *     drag checks.
     * @returns Connection.CAN_CONNECT if the connection is legal, an error code
     *     otherwise.
     */
    canConnectWithReason(a: Connection | null, b: Connection | null, isDragging: boolean, opt_distance?: number): number;
    /**
     * Helper method that translates a connection error code into a string.
     *
     * @param errorCode The error code.
     * @param a One of the two connections being checked.
     * @param b The second of the two connections being checked.
     * @returns A developer-readable error string.
     */
    getErrorMessage(errorCode: number, a: Connection | null, b: Connection | null): string;
    /**
     * Check that connecting the given connections is safe, meaning that it would
     * not break any of Blockly's basic assumptions (e.g. no self connections).
     *
     * @param a The first of the connections to check.
     * @param b The second of the connections to check.
     * @returns An enum with the reason this connection is safe or unsafe.
     */
    doSafetyChecks(a: Connection | null, b: Connection | null): number;
    /**
     * Check whether this connection is compatible with another connection with
     * respect to the value type system.  E.g. square_root("Hello") is not
     * compatible.
     *
     * @param a Connection to compare.
     * @param b Connection to compare against.
     * @returns True if the connections share a type.
     */
    doTypeChecks(a: Connection, b: Connection): boolean;
    /**
     * Check whether this connection can be made by dragging.
     *
     * @param a Connection to compare (on the block that's being dragged).
     * @param b Connection to compare against.
     * @param distance The maximum allowable distance between connections.
     * @returns True if the connection is allowed during a drag.
     */
    doDragChecks(a: RenderedConnection, b: RenderedConnection, distance: number): boolean;
    /**
     * Helper function for drag checking.
     *
     * @param a The connection to check, which must be a statement input or next
     *     connection.
     * @param b A nearby connection to check, which must be a previous connection.
     * @returns True if the connection is allowed, false otherwise.
     */
    protected canConnectToPrevious_(a: Connection, b: Connection): boolean;
}
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