import type { ChatContextTokenUsage, TokenUsageType } from '.';
import type { ModelContextWindow } from '..';
import type { Message, PromptString } from '..';
/**
 * A class to manage the token allocation during prompt building.
 */
export declare class TokenCounter {
    /**
     * The maximum number of tokens that can be used by Chat Messages.
     */
    readonly maxChatTokens: number;
    /**
     * The maximum number of tokens that can be used by each context type:
     * - User-Context: tokens reserved for User-added context, like @-mentions.
     * - Enhanced-Context: % (defined by ENHANCED_CONTEXT_ALLOCATION) of the latest Chat budget.
     */
    readonly maxContextTokens: ChatContextTokenUsage;
    /**
     * The number of tokens used by chat and context respectively.
     */
    private usedTokens;
    /**
     * Indicates whether the Chat and User-Context share the same token budget.
     * - If true, all types of messages share the same token budget with Chat.
     * - If false (Feature Flag required), the User-Context will has a separated budget.
     * NOTE: Used in remainingTokens for calculating the remaining token budget for each budget type.
     */
    private shareChatAndUserBudget;
    constructor(contextWindow: ModelContextWindow);
    /**
     * Updates the token usage for the messages of a specified token usage type.
     *
     * @param type - The type of token usage to update.
     * @param messages - The messages to calculate the token count for.
     * @returns `true` if the token usage can be allocated, `false` otherwise.
     */
    updateUsage(type: TokenUsageType, messages: Message[]): boolean;
    /**
     * NOTE: Should only be used by @canAllocateTokens to determine if the token usage can be allocated in correct order.
     *
     * Calculates the remaining token budget for each token usage type.
     *
     * @returns The remaining token budget for chat, User-Context, and Enhanced-Context (if applicable).
     */
    private get remainingTokens();
    /**
     * Checks if the specified token usage type has enough remaining tokens to allocate the given count.
     *
     * @param type - The type of token usage to check.
     * @param count - The number of tokens to allocate.
     * @returns `true` if the tokens can be allocated, `false` otherwise.
     */
    private canAllocateTokens;
    /**
     * The default tokenizer is cl100k_base.
     */
    private static tokenizer;
    /**
     * Encode the given text using the tokenizer.
     * The text is first normalized to NFKC to handle different character representations consistently.
     * All special tokens are included in the token count.
     */
    static encode(text: string): number[];
    static decode(encoded: number[]): string;
    /**
     * Counts the number of tokens in the given text using the tokenizer.
     *
     * @param text - The input text to count tokens for.
     * @returns The number of tokens in the input text.
     */
    static countTokens(text: string): number;
    static countPromptString(text: PromptString): number;
    /**
     * Counts the number of tokens in the given message using the tokenizer.
     *
     * @param message - The message to count tokens for.
     * @returns The number of tokens in the message.
     */
    private static getTokenCountForMessage;
    /**
     * Calculates the total number of tokens across the given array of messages.
     *
     * @param messages - An array of messages to count the tokens for.
     * @returns The total number of tokens in the provided messages.
     */
    static getMessagesTokenCount(messages: Message[]): number;
}
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