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generics.dart
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generics.dart
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/// Author: Yohan Beschi
/**
* Entry Point
*/
void main() {
//---- Validator
Validator validator = new Validator();
bool isValid = validator.validate(new User('', ''));
assert(isValid);
//---- Validator as interface
Validator userValidator = new LoginService();
bool isValid2 = userValidator.validate(new User('', ''));
assert(!isValid2);
bool isValid3 = userValidator.validate(new User('Foo', r'pa$$word'));
assert(isValid3);
//---- Check as inteface
Processor processor = userValidator as Processor;
bool processed = processor.process(new User('not', 'found'));
assert(!processed);
processed = processor.process(new User('root', 'secure'));
assert(processed);
//---- Full Login
User user = new User('root', 'secure');
LoginService login = new LoginService();
assert(login.validate(user));
assert(login.process(user));
}
abstract class Validatable {
List<Object> valuesToValidate();
}
class Validator<T extends Validatable> {
bool validate(T object) {
for (Object obj in object.valuesToValidate()) {
if (StringUtils.isEmpty(obj.toString())) {
return false;
}
}
return true;
}
}
class User implements Validatable {
String username;
String password;
User(this.username, this.password);
List<Object> valuesToValidate() {
return [username, password];
}
}
abstract class Processor<T> {
bool process(T t);
}
class LoginService implements Validator<User>, Processor {
static List<User> USERS_DB = [new User('root', 'secure')];
bool validate(User user) {
if (StringUtils.isBlank(user.password)) {
return false;
}
if (StringUtils.isBlank(user.username)) {
return false;
}
return true;
}
bool process(User user) {
if (LoginService.contains(USERS_DB, user)) {
return true;
} else {
return false;
}
}
static bool contains(List<User> users, User user) {
for (User u in users) {
if (u.username == user.username
&& u.password == user.password) {
return true;
}
}
return false;
}
}
class StringUtils {
static bool isEmpty(String s) {
return s == null;
}
static bool isNotEmpty(String s) {
return !StringUtils.isEmpty(s);
}
static bool isBlank(String s) {
return StringUtils.isEmpty(s) || s.length == 0;
}
static bool isNotBlank(String s) {
return !StringUtils.isBlank(s);
}
}