Basic Examples: Mixins and typedefs in Dart

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Basic Examples: Mixins and typedefs in Dart

Basic examples of using mixins and typedefs in Dart

Find this at dartpad.dartlang.org/adb3ebb1f08c692eea5f30018b5cd046.

main.dart

d(id) => new Document(id.toString()); //convenience function
List<Document> docs = [d('Foo'), d('bar'), d('BIZ'), d('Baz'), d('fab')];

///A simple document class with id
class Document {
  String id;
  Document(this.id);
  toString() => id;
}

///Any function that meets this signature is a Matcher
typedef bool Matcher(String s, Document d);

abstract class AbstractDocumentRepo {
  ///The store of documents
  List<Document> _repo; 
  
  AbstractDocumentRepo(this._repo);
  
  ///Search the documents, returning a list of matched docs
  List<Document> search(String term) => _repo.where( (doc) => matcher(term, doc));
  
  ///A matching strategy for documents
  Matcher get matcher;
}


class CaseSensitiveMatchingBehavior {
  Matcher get matcher => (String s, Document d) => d.id.contains(s);
}

class CaseInsensitiveMatchingBehavior {
  Matcher get matcher => (String s, Document d) => d.id.toLowerCase().contains(s.toLowerCase());
}

class SensitiveDocRepo extends AbstractDocumentRepo with CaseSensitiveMatchingBehavior {
  SensitiveDocRepo(r): super(r);
}

class InsensitiveDocRepo extends AbstractDocumentRepo with CaseInsensitiveMatchingBehavior {
  InsensitiveDocRepo(r): super(r);
}

class CustomDocRepo extends AbstractDocumentRepo {
  CustomDocRepo(r): super(r);  
  Matcher get matcher => (String s, Document d) => d.id == s;
}

main() async {
  print(" * Starting *");

  AbstractDocumentRepo r1 = new SensitiveDocRepo(docs);
  AbstractDocumentRepo r2 = new InsensitiveDocRepo(docs);
  AbstractDocumentRepo r3 = new CustomDocRepo(docs);

  print(r1.search("B"));
  print(r2.search("B"));
  print(r3.search("Baz"));
  
  print("Is r1 case sensitive? ${r1 is CaseSensitiveMatchingBehavior}");
  print("Is r1 case insensitive? ${r1 is CaseInsensitiveMatchingBehavior}");

  print("Is r1.matcher a matcher? ${r1.matcher is Matcher}");
  Function f = (String s, Document d) => false;
  print("Is f a matcher? ${f is Matcher}");
  Function g = (String s) => false;
  print("Is g a matcher? ${g is Matcher}");
  Function h = (String s, Document d) => s;
  print("Is h a matcher? ${h is Matcher}");
   
  print(" * Ending * "); 
}