build.dart

/*
 * Deployes dart packages.
 *
 * Takes the dart packages in directory 
 *   /source/dir/packages/...
 * which is configured in the configuration files build.json,
 * i.e.
 *     {"packages-dir": "/source/dir(packages"}
 * 
 * and copies them to the directory 
 *   ./packages 
 * by resolving any symlinks
 */
import "dart:async";
import "dart:io";
import "dart:json" as json;

var _OPTIONS;

readOptions() {
  var config = new File("build.json");
  if (!config.existsSync()) {
    print("fatal: configuration file 'build.json' missing.");
    exit(1);
  }
  _OPTIONS = json.parse(
    config.readAsStringSync()
  );
}

/// represents a dart package 
class Package {
  /// the package name, i.e. "meta"
  final String name;
  /// the absolute path to the local package repository
  final String repo;
  Package(this.name, this.repo);
}

/// replies a stream of package infos
Stream<Package> packages() {
  var controller = new StreamController();
  var dir = new Directory(_OPTIONS["packages-dir"]);
  dir.list().where((e) => e is Directory).listen((d) {
    var name = new Path(d.path).filename;

    // resolve symlinks 
    Process.run("/bin/readlink", ["-f", d.path]).then((result) {
      var repo = result.stdout.trim();
      controller.sink.add(new Package(name, repo));
    });
  });
  return controller.stream;
}

recreatePackagesDir() {
  var packages = new Directory("packages");
  if (packages.existsSync()) {
    print("'packages': deleting ...");
    packages.deleteSync(recursive: true);
  }
  print("'packages': creating ...");
  packages.createSync();
}

deployPackage(package) {
  var dir = new Directory("packages/${package.name}");
  print("creating package dir '$dir.path' ...");
  dir.createSync(recursive:true);
  print("copying package: ${package.repo} -> packages/${package.name} ...");
  Process.run("cp", ["-R", package.repo, "packages/${package.name}"]).then((result){});
}

main() {
  readOptions();
  var packages = packages();
  recreatePackagesDir();
  packages.listen((p) {
    deployPackage(p);
  });
}

build.json

{
  "packages-dir": "/loccal/package/source/dir/packages"
}