/*!
* Copyright 2016 The ANTLR Project. All rights reserved.
* Licensed under the BSD-3-Clause license. See LICENSE file in the project root for license information.
*/
import { CharStream } from "../CharStream";
import { Lexer } from "../Lexer";
import { LexerAction } from "./LexerAction";
/**
* Represents an executor for a sequence of lexer actions which traversed during
* the matching operation of a lexer rule (token).
*
* The executor tracks position information for position-dependent lexer actions
* efficiently, ensuring that actions appearing only at the end of the rule do
* not cause bloating of the {@link DFA} created for the lexer.
*
* @author Sam Harwell
* @since 4.2
*/
export declare class LexerActionExecutor {
private _lexerActions;
/**
* Caches the result of {@link #hashCode} since the hash code is an element
* of the performance-critical {@link LexerATNConfig#hashCode} operation.
*/
private cachedHashCode;
/**
* Constructs an executor for a sequence of {@link LexerAction} actions.
* @param lexerActions The lexer actions to execute.
*/
constructor(lexerActions: LexerAction[]);
/**
* Creates a {@link LexerActionExecutor} which executes the actions for
* the input `lexerActionExecutor` followed by a specified
* `lexerAction`.
*
* @param lexerActionExecutor The executor for actions already traversed by
* the lexer while matching a token within a particular
* {@link ATNConfig}. If this is `undefined`, the method behaves as though
* it were an empty executor.
* @param lexerAction The lexer action to execute after the actions
* specified in `lexerActionExecutor`.
*
* @returns A {@link LexerActionExecutor} for executing the combine actions
* of `lexerActionExecutor` and `lexerAction`.
*/
static append(lexerActionExecutor: LexerActionExecutor | undefined, lexerAction: LexerAction): LexerActionExecutor;
/**
* Creates a {@link LexerActionExecutor} which encodes the current offset
* for position-dependent lexer actions.
*
* Normally, when the executor encounters lexer actions where
* {@link LexerAction#isPositionDependent} returns `true`, it calls
* {@link IntStream#seek} on the input {@link CharStream} to set the input
* position to the *end* of the current token. This behavior provides
* for efficient DFA representation of lexer actions which appear at the end
* of a lexer rule, even when the lexer rule matches a variable number of
* characters.
*
* Prior to traversing a match transition in the ATN, the current offset
* from the token start index is assigned to all position-dependent lexer
* actions which have not already been assigned a fixed offset. By storing
* the offsets relative to the token start index, the DFA representation of
* lexer actions which appear in the middle of tokens remains efficient due
* to sharing among tokens of the same length, regardless of their absolute
* position in the input stream.
*
* If the current executor already has offsets assigned to all
* position-dependent lexer actions, the method returns `this`.
*
* @param offset The current offset to assign to all position-dependent
* lexer actions which do not already have offsets assigned.
*
* @returns A {@link LexerActionExecutor} which stores input stream offsets
* for all position-dependent lexer actions.
*/
fixOffsetBeforeMatch(offset: number): LexerActionExecutor;
/**
* Gets the lexer actions to be executed by this executor.
* @returns The lexer actions to be executed by this executor.
*/
get lexerActions(): LexerAction[];
/**
* Execute the actions encapsulated by this executor within the context of a
* particular {@link Lexer}.
*
* This method calls {@link IntStream#seek} to set the position of the
* `input` {@link CharStream} prior to calling
* {@link LexerAction#execute} on a position-dependent action. Before the
* method returns, the input position will be restored to the same position
* it was in when the method was invoked.
*
* @param lexer The lexer instance.
* @param input The input stream which is the source for the current token.
* When this method is called, the current {@link IntStream#index} for
* `input` should be the start of the following token, i.e. 1
* character past the end of the current token.
* @param startIndex The token start index. This value may be passed to
* {@link IntStream#seek} to set the `input` position to the beginning
* of the token.
*/
execute(lexer: Lexer, input: CharStream, startIndex: number): void;
hashCode(): number;
equals(obj: any): boolean;
}
