beth-parser/dist/source/FileSource.js

Parser library for Bethesda's Creation Engine data files

"use strict";
exports.__esModule = true;
var fs = require("fs");
/**
 * Node.js based file data source using single internal read buffer.
 *
 * When specifying internal buffer size (i.e. not relying on the default value), keep in mind that
 * every read request that can't fit inside that buffer will result in a new buffer allocation.
 */
var FileSource = /** @class */ (function () {
    /**
     * @param path Source file path.
     * @param bufferSize Size of the internal source buffer.
     */
    function FileSource(path, bufferSize) {
        if (bufferSize === void 0) { bufferSize = 0x3fff; }
        /**
         * Current read position.
         */
        this.filePosition = 0;
        /**
         * Cursor position inside source buffer.
         */
        this.bufferOffset = 0;
        /**
         * Actual data length inside source buffer.
         */
        this.bufferLength = 0;
        this.fileDesc = fs.openSync(path, "r");
        this.sourceBuffer = Buffer.alloc(bufferSize || 0x3fff);
    }
    /**
     * Read another portion of the file into the target buffer.
     */
    FileSource.prototype.readFile = function (buffer) {
        var reminderLength = this.bufferLength - this.bufferOffset;
        // Copy buffer reminder to the beginning of the target buffer
        this.sourceBuffer.copy(buffer, 0, this.bufferOffset, this.bufferLength);
        // Reset read length and position
        this.bufferLength = 0;
        this.bufferOffset = 0;
        // Try to read the rest of the buffer
        var bytesRead = fs.readSync(this.fileDesc, buffer, reminderLength, buffer.length - reminderLength, this.filePosition);
        this.filePosition += bytesRead;
        return buffer.subarray(0, reminderLength + bytesRead);
    };
    /**
     * Read data using the internal source buffer.
     */
    FileSource.prototype.readBuffer = function (length) {
        if (this.bufferOffset + length > this.bufferLength) {
            this.bufferLength = this.readFile(this.sourceBuffer).length;
        }
        if (this.bufferOffset + length > this.bufferLength) {
            length = this.bufferLength;
        }
        this.bufferOffset += length;
        return this.sourceBuffer.subarray(this.bufferOffset - length, this.bufferOffset);
    };
    FileSource.prototype.read = function (length) {
        if (length > this.sourceBuffer.length) {
            return this.readFile(Buffer.alloc(length));
        }
        else {
            return this.readBuffer(length);
        }
    };
    FileSource.prototype.skip = function (length) {
        this.bufferOffset += length;
        if (this.bufferOffset > this.bufferLength) {
            this.filePosition += this.bufferOffset - this.bufferLength;
            this.bufferOffset = 0;
            this.bufferLength = 0;
        }
    };
    FileSource.prototype.close = function () {
        fs.closeSync(this.fileDesc);
    };
    FileSource.prototype.cursor = function () {
        return this.filePosition - this.bufferLength + this.bufferOffset;
    };
    return FileSource;
}());
exports["default"] = FileSource;
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