@talex/electron-windows-store/lib/vendor/tail.js

Compile Electron Apps into Windows Store AppX packages

// Taken from https://github.com/lucagrulla/node-tail
// and hacked to accept UTF16LE 

var Tail, environment, events, fs,
    bind = function (fn, me) { return function () { return fn.apply(me, arguments); }; },
    extend = function (child, parent) { for (var key in parent) { if (hasProp.call(parent, key)) child[key] = parent[key]; } function ctor() { this.constructor = child; } ctor.prototype = parent.prototype; child.prototype = new ctor(); child.__super__ = parent.prototype; return child; },
    hasProp = {}.hasOwnProperty;

events = require("events");

fs = require('fs');

environment = process.env['NODE_ENV'] || 'development';

Tail = (function (superClass) {
    extend(Tail, superClass);

    Tail.prototype.readBlock = function () {
        var block, stream;
        if (this.queue.length >= 1) {
            block = this.queue.shift();
            if (block.end > block.start) {
                stream = fs.createReadStream(this.filename, {
                    start: block.start,
                    end: block.end - 1,
                    encoding: "utf16le"
                });
                stream.on('error', (function (_this) {
                    return function (error) {
                        console.error("Tail error:" + error);
                        return _this.emit('error', error);
                    };
                })(this));
                stream.on('end', (function (_this) {
                    return function () {
                        if (_this.queue.length >= 1) {
                            return _this.internalDispatcher.emit("next");
                        }
                    };
                })(this));
                return stream.on('data', (function (_this) {
                    return function (data) {
                        var chunk, i, len, parts, results;
                        _this.buffer += data;
                        parts = _this.buffer.split(_this.separator);
                        _this.buffer = parts.pop();
                        results = [];
                        for (i = 0, len = parts.length; i < len; i++) {
                            chunk = parts[i];
                            results.push(_this.emit("line", chunk));
                        }
                        return results;
                    };
                })(this));
            }
        }
    };

    function Tail(filename, options) {
        var pos, ref, ref1, ref2, ref3;
        this.filename = filename;
        if (options == null) {
            options = {};
        }
        this.readBlock = bind(this.readBlock, this);
        this.separator = (ref = options.separator) != null ? ref : /[\r]{0,1}\n/, this.fsWatchOptions = (ref1 = options.fsWatchOptions) != null ? ref1 : {}, this.fromBeginning = (ref2 = options.fromBeginning) != null ? ref2 : false, this.follow = (ref3 = options.follow) != null ? ref3 : true;
        this.buffer = '';
        this.internalDispatcher = new events.EventEmitter();
        this.queue = [];
        this.isWatching = false;
        this.internalDispatcher.on('next', (function (_this) {
            return function () {
                return _this.readBlock();
            };
        })(this));
        if (this.fromBeginning) {
            pos = 0;
        }
        this.watch(pos);
    }

    Tail.prototype.watch = function (pos) {
        var stats;
        if (this.isWatching) {
            return;
        }
        this.isWatching = true;
        stats = fs.statSync(this.filename);
        this.pos = pos != null ? pos : stats.size;
        if (fs.watch) {
            return this.watcher = fs.watch(this.filename, this.fsWatchOptions, (function (_this) {
                return function (e) {
                    return _this.watchEvent(e);
                };
            })(this));
        } else {
            return fs.watchFile(this.filename, this.fsWatchOptions, (function (_this) {
                return function (curr, prev) {
                    return _this.watchFileEvent(curr, prev);
                };
            })(this));
        }
    };

    Tail.prototype.watchEvent = function (e) {
        var stats;
        if (e === 'change') {
            stats = fs.statSync(this.filename);
            if (stats.size < this.pos) {
                this.pos = stats.size;
            }
            if (stats.size > this.pos) {
                this.queue.push({
                    start: this.pos,
                    end: stats.size
                });
                this.pos = stats.size;
                if (this.queue.length === 1) {
                    return this.internalDispatcher.emit("next");
                }
            }
        } else if (e === 'rename') {
            this.unwatch();
            if (this.follow) {
                return setTimeout(((function (_this) {
                    return function () {
                        return _this.watch();
                    };
                })(this)), 1000);
            } else {
                console.error("'rename' event for " + this.filename + ". File not available.");
                return this.emit("error", "'rename' event for " + this.filename + ". File not available.");
            }
        }
    };

    Tail.prototype.watchFileEvent = function (curr, prev) {
        if (curr.size > prev.size) {
            this.queue.push({
                start: prev.size,
                end: curr.size
            });
            if (this.queue.length === 1) {
                return this.internalDispatcher.emit("next");
            }
        }
    };

    Tail.prototype.unwatch = function () {
        if (fs.watch && this.watcher) {
            this.watcher.close();
        } else {
            fs.unwatchFile(this.filename);
        }
        this.isWatching = false;
        return this.queue = [];
    };

    return Tail;

})(events.EventEmitter);

exports.Tail = Tail;