TrinetraLabs/Placebo_AI

1"use strict";2var utils = require("../utils");3 4function DataReader(data) {5    this.data = data; // type : see implementation6    this.length = data.length;7    this.index = 0;8    this.zero = 0;9}10DataReader.prototype = {11    /**12     * Check that the offset will not go too far.13     * @param {string} offset the additional offset to check.14     * @throws {Error} an Error if the offset is out of bounds.15     */16    checkOffset: function(offset) {17        this.checkIndex(this.index + offset);18    },19    /**20     * Check that the specified index will not be too far.21     * @param {string} newIndex the index to check.22     * @throws {Error} an Error if the index is out of bounds.23     */24    checkIndex: function(newIndex) {25        if (this.length < this.zero + newIndex || newIndex < 0) {26            throw new Error("End of data reached (data length = " + this.length + ", asked index = " + (newIndex) + "). Corrupted zip ?");27        }28    },29    /**30     * Change the index.31     * @param {number} newIndex The new index.32     * @throws {Error} if the new index is out of the data.33     */34    setIndex: function(newIndex) {35        this.checkIndex(newIndex);36        this.index = newIndex;37    },38    /**39     * Skip the next n bytes.40     * @param {number} n the number of bytes to skip.41     * @throws {Error} if the new index is out of the data.42     */43    skip: function(n) {44        this.setIndex(this.index + n);45    },46    /**47     * Get the byte at the specified index.48     * @param {number} i the index to use.49     * @return {number} a byte.50     */51    byteAt: function() {52        // see implementations53    },54    /**55     * Get the next number with a given byte size.56     * @param {number} size the number of bytes to read.57     * @return {number} the corresponding number.58     */59    readInt: function(size) {60        var result = 0,61            i;62        this.checkOffset(size);63        for (i = this.index + size - 1; i >= this.index; i--) {64            result = (result << 8) + this.byteAt(i);65        }66        this.index += size;67        return result;68    },69    /**70     * Get the next string with a given byte size.71     * @param {number} size the number of bytes to read.72     * @return {string} the corresponding string.73     */74    readString: function(size) {75        return utils.transformTo("string", this.readData(size));76    },77    /**78     * Get raw data without conversion, <size> bytes.79     * @param {number} size the number of bytes to read.80     * @return {Object} the raw data, implementation specific.81     */82    readData: function() {83        // see implementations84    },85    /**86     * Find the last occurrence of a zip signature (4 bytes).87     * @param {string} sig the signature to find.88     * @return {number} the index of the last occurrence, -1 if not found.89     */90    lastIndexOfSignature: function() {91        // see implementations92    },93    /**94     * Read the signature (4 bytes) at the current position and compare it with sig.95     * @param {string} sig the expected signature96     * @return {boolean} true if the signature matches, false otherwise.97     */98    readAndCheckSignature: function() {99        // see implementations100    },101    /**102     * Get the next date.103     * @return {Date} the date.104     */105    readDate: function() {106        var dostime = this.readInt(4);107        return new Date(Date.UTC(108            ((dostime >> 25) & 0x7f) + 1980, // year109            ((dostime >> 21) & 0x0f) - 1, // month110            (dostime >> 16) & 0x1f, // day111            (dostime >> 11) & 0x1f, // hour112            (dostime >> 5) & 0x3f, // minute113            (dostime & 0x1f) << 1)); // second114    }115};116module.exports = DataReader;117