Reading file line by line in dart

Question

I'm trying to process large text files in a language Dart. The files have a size over 100 MB.

I tried readAsLines and readAsLinesSync methods of dart:io library. Every time I run out of memory: Exhausted heap space.

Is there a way to read a file line by line or byte by byte as in other languages​​?

Answer 1

This should read the file in chunks:

import 'dart:async';
import 'dart:io';
import 'dart:convert';

main() {
  var path = ...;
  new File(path)
    .openRead()
    .map(utf8.decode)
    .transform(new LineSplitter())
    .forEach((l) => print('line: $l'));
}

There isn't much documentation about this yet. Perhaps file a bug asking for more docs.

Answer 2

In the latest verion of dart the UTF8.decoder is now utf8.decoder:

import 'dart:async';
import 'dart:io';
import 'dart:convert';

main() {
  var path = ...;
  new File(path)
    .openRead()
    .transform(utf8.decoder)
    .transform(new LineSplitter())
    .forEach((l) => print('line: $l'));
}