@syncfusion/ej2-pdf/src/pdf/core/compression/huffman-tree.d.ts

Feature-rich JavaScript PDF library with built-in support for loading and manipulating PDF document.

import { _InBuffer } from './in-buffer';
/**
 * Implements a Huffman decoding table with fast lookup and tree traversal.
 *
 * @private
 */
export declare class _HuffmanTree {
    /**
     * Maximum number of codes in the length/literal tree.
     *
     * @private
     */
    static _maxLengthTree: number;
    /**
     * Maximum tree depth supported.
     *
     * @private
     */
    static _maxDepthTree: number;
    /**
     * Number of code length codes.
     *
     * @private
     */
    static _nCLength: number;
    /**
     * Number of bits used for initial table lookup.
     *
     * @private
     */
    _tBits: number;
    /**
     * Lookup table for fast Huffman decoding.
     *
     * @private
     */
    _table: number[];
    /**
     * Left child indices for the Huffman tree.
     *
     * @private
     */
    _left: number[];
    /**
     * Right child indices for the Huffman tree.
     *
     * @private
     */
    _right: number[];
    /**
     * Array of code lengths for symbols.
     *
     * @private
     */
    _clArray: number[];
    /**
     * Bit mask applied to table lookups.
     *
     * @private
     */
    _tMask: number;
    /**
     * Loads the code length array and builds the decoding structures.
     *
     * @private
     * @param {number[]} code Code length array.
     * @returns {void} nothing.
     */
    _load(code: number[]): void;
    /**
     * Loads the predefined length or distance tree and builds the decoding structures.
     *
     * @private
     * @param {boolean} isLengthTree Whether the tree is a literal/length tree.
     * @returns {void} nothing.
     */
    _loadTree(isLengthTree: boolean): void;
    /**
     * Initializes table size and bit mask and creates the primary decode table.
     *
     * @private
     * @returns {void} nothing.
     */
    _initialize(): void;
    /**
     * Returns the fixed Huffman code lengths for the literal/length alphabet.
     *
     * @private
     * @returns {number[]} lengthTree.
     */
    _getLengthTree(): number[];
    /**
     * Returns the fixed Huffman code lengths for the distance alphabet.
     *
     * @private
     * @returns {number[]} depthTree.
     */
    _getDepthTree(): number[];
    /**
     * Computes canonical Huffman codes for symbols based on code lengths.
     *
     * @private
     * @returns {number[]} canonicalCodes.
     */
    _calculateHashCode(): number[];
    /**
     * Reverses the lowest `length` bits of the given value.
     *
     * @private
     * @param {number} code Code value.
     * @param {number} length Number of bits to reverse.
     * @returns {number} reversedCode.
     */
    _bitReverse(code: number, length: number): number;
    /**
     * Builds the fast lookup table and associated tree nodes for Huffman decoding.
     *
     * @private
     * @returns {void} nothing.
     */
    _createTable(): void;
    /**
     * Decodes and returns the next symbol from the input bit buffer.
     *
     * @private
     * @param {_InBuffer} input Bitwise input buffer.
     * @returns {number} symbol or -1 if insufficient bits.
     */
    _getNextSymbol(input: _InBuffer): number;
}