61 lines
1.9 KiB
JavaScript
61 lines
1.9 KiB
JavaScript
var fs = require('fs'),
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EventEmitter = require('events').EventEmitter,
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util = require('util');
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var readLine = module.exports = function(file, opts) {
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if (!(this instanceof readLine)) return new readLine(file, opts);
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EventEmitter.call(this);
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opts = opts || {};
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opts.maxLineLength = opts.maxLineLength || 4096; // 4K
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opts.retainBuffer = !!opts.retainBuffer; //do not convert to String prior to invoking emit 'line' event
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var self = this,
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lineBuffer = new Buffer(opts.maxLineLength),
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lineLength = 0,
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lineCount = 0,
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byteCount = 0,
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emit = function(lineCount, byteCount) {
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try {
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var line = lineBuffer.slice(0, lineLength);
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self.emit('line', opts.retainBuffer? line : line.toString(), lineCount, byteCount);
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} catch (err) {
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self.emit('error', err);
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} finally {
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lineLength = 0; // Empty buffer.
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}
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};
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this.input = ('string' === typeof file) ? fs.createReadStream(file, opts) : file;
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this.input.on('open', function(fd) {
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self.emit('open', fd);
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})
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.on('data', function(data) {
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for (var i = 0; i < data.length; i++) {
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if (data[i] == 10 || data[i] == 13) { // Newline char was found.
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if (data[i] == 10) {
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lineCount++;
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emit(lineCount, byteCount);
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}
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} else {
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lineBuffer[lineLength] = data[i]; // Buffer new line data.
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lineLength++;
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}
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byteCount++;
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}
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})
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.on('error', function(err) {
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self.emit('error', err);
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})
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.on('end', function() {
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// Emit last line if anything left over since EOF won't trigger it.
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if (lineLength) {
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lineCount++;
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emit(lineCount, byteCount);
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}
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self.emit('end');
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})
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.on('close', function() {
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self.emit('close');
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});
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};
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util.inherits(readLine, EventEmitter);
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