LineStream.js
[Node.js] ReadableStream of lines
Installation
$ npm install linestream
OR
$ git clone git://github.com/shinout/LineStream.git
sample
with file
var stream = require('linestream').create(filename, {bufferSize: 300});
stream.on('data', function(line, isEnd) {
console.log(line); // each line comes here
console.log(isEnd); // if it is the end of data or not.
})
stream.on('end', function() { // emitted at the end of file
console.log('end');
});
stream.on('error', function(e) { // emitted when an error occurred
console.error(e);
});
with Stream (like HttpResponse)
var https = require('https');
var req = https.request({host: 'github.com'}, function(response) {
var stream = require('linestream').create(response);
stream.on('data', function(line) {
console.log(line); // each line comes here
});
});
req.end();
API Documentation
LineStream extends ReadableStream.
See Node.js#Stream for ReadableStream's API.
- LineStream.create(source, options)
- on "data"
- LineStream.tsv(source, [options], fn)
- stream.after(rstream1, rstream2, ...)
LineStream.create(source, options)
Creates an instance of LineStream.
source is the one of the followings.
- (string) filename. Then reads the file and emit each lines.
- "-". Then resumes process.stdin and reads from it.
- (ReadableStream) stream. Then reads lines from the stream.
(Object) options is optional.
| key | type | description | example |
|---|---|---|---|
| separator | string | line separator. "\n" by default. |
"\r" |
| trim | boolean | If true, separator are not appended in the line. true by default. |
false |
| filter | function | filter function before emitting lines. each line is passed to the function as the first argument. |
function (line) { return line.length } |
| comment | string | Registers the marks of one-line comment. If the mark comes in the first position of a line, the line is filtered. | "#" |
| fieldSep | string | A field separator. It is used with fieldNum options. | "\t" |
| fieldNum | string | the required number of the fields. If not matched, the line is filtered. |
6 |
| empty | boolean | If true, empty lines (after trimmed) are filtered. | true |
Other options are passed to fs.createReadStream(filename, options) if the first argument is a string.
on "data"
Data event of LineStream. Two arguments are passed.
- line (string) each line
- isEnd (boolean) whether the line is final or not.
example
stream.on("data", function(line, isEnd) {
console.log([line, isEnd].join('\t'));
});
LineStream.tsv(source, [options], fn)
Creates an instance of LineStream, with field separated by "\t".
source and options are the same as LineStream.create(source, options).
fn is called on "data" event. Three arguments are passed.
- data (Array)
- line (string)
- isEnd (boolean)
data is equivalent to line.split("\t")
Other arguments are the same as original "data" event.
Returns an instance of LineStream.
stream.after(rstream1, rstream2, ...)
Pauses the stream until all passed readable streams come to an end.
var ids = {};
var comingLines = LineStream.tsv('-', function(data, line, isEnd) { // reads from process.stdin
var id = data[0];
ids[id] = true;
});
LineStream.tsv('file1', function(data, line, isEnd) { // reads from "file1"
var id = data[0];
if (ids[id]) console.log(line);
})
.after(comingLines); // resumes after comingLines finished,
