AddressBook: remove master tag list (#149)

We keep track of a master tag list which holds all the tags in
AddressBook.

As the master tag list was deemed unnecessary and may be too
complex for new developers to grasp, as discussed in
se-edu/addressbook-level4#753 and se-edu/addressbook-level4#794,
the master tag list has already been removed in AB4
by se-edu/addressbook-level4#825.

UniqueTagList was also deemed unnecessary and removed in
addressbook-level4 after the master tag list is removed.

As such, the master tag list and UniqueTagList class should also be
removed in the lower level projects.

Let's remove the master tag list in AddressBook and AdaptedAddressBook,
as well as the UniqueTagList class.

src/seedu/addressbook/commands/AddCommand.java

@@ -3,7 +3,6 @@
 import seedu.addressbook.data.exception.IllegalValueException;
 import seedu.addressbook.data.person.*;
 import seedu.addressbook.data.tag.Tag;
-import seedu.addressbook.data.tag.UniqueTagList;
 
 import java.util.HashSet;
 import java.util.Set;
@@ -45,7 +44,7 @@ public AddCommand(String name,
                 new Phone(phone, isPhonePrivate),
                 new Email(email, isEmailPrivate),
                 new Address(address, isAddressPrivate),
-                new UniqueTagList(tagSet)
+                tagSet
         );
     }
 

src/seedu/addressbook/data/AddressBook.java

@@ -1,24 +1,17 @@
 package seedu.addressbook.data;
 
-import seedu.addressbook.data.person.*;
-import seedu.addressbook.data.person.UniquePersonList.*;
-import seedu.addressbook.data.tag.Tag;
-import seedu.addressbook.data.tag.UniqueTagList;
-import seedu.addressbook.data.tag.UniqueTagList.*;
-
-import java.util.*;
+import seedu.addressbook.data.person.Person;
+import seedu.addressbook.data.person.ReadOnlyPerson;
+import seedu.addressbook.data.person.UniquePersonList;
+import seedu.addressbook.data.person.UniquePersonList.DuplicatePersonException;
+import seedu.addressbook.data.person.UniquePersonList.PersonNotFoundException;
 
 /**
  * Represents the entire address book. Contains the data of the address book.
- *
- * Guarantees:
- *  - Every tag found in every person will also be found in the tag list.
- *  - The tags in each person point to tag objects in the master list. (== equality)
  */
 public class AddressBook {
 
     private final UniquePersonList allPersons;
-    private final UniqueTagList allTags; // can contain tags not attached to any person
 
     public static AddressBook empty() {
         return new AddressBook();
@@ -29,56 +22,23 @@ public static AddressBook empty() {
      */
     public AddressBook() {
         allPersons = new UniquePersonList();
-        allTags = new UniqueTagList();
     }
 
     /**
      * Constructs an address book with the given data.
-     * Also updates the tag list with any missing tags found in any person.
      *
      * @param persons external changes to this will not affect this address book
-     * @param tags external changes to this will not affect this address book
      */
-    public AddressBook(UniquePersonList persons, UniqueTagList tags) {
+    public AddressBook(UniquePersonList persons) {
         this.allPersons = new UniquePersonList(persons);
-        this.allTags = new UniqueTagList(tags);
-        for (Person p : allPersons) {
-            syncTagsWithMasterList(p);
-        }
-    }
-
-    /**
-     * Ensures that every tag in this person:
-     *  - exists in the master list {@link #allTags}
-     *  - points to a Tag object in the master list
-     */
-    private void syncTagsWithMasterList(Person person) {
-        final UniqueTagList personTags = person.getTags();
-        allTags.mergeFrom(personTags);
-
-        // Create map with values = tag object references in the master list
-        final Map<Tag, Tag> masterTagObjects = new HashMap<>();
-        for (Tag tag : allTags) {
-            masterTagObjects.put(tag, tag);
-        }
-
-        // Rebuild the list of person tags using references from the master list
-        final Set<Tag> commonTagReferences = new HashSet<>();
-        for (Tag tag : personTags) {
-            commonTagReferences.add(masterTagObjects.get(tag));
-        }
-        person.setTags(new UniqueTagList(commonTagReferences));
     }
 
     /**
      * Adds a person to the address book.
-     * Also checks the new person's tags and updates {@link #allTags} with any new tags found,
-     * and updates the Tag objects in the person to point to those in {@link #allTags}.
      *
      * @throws DuplicatePersonException if an equivalent person already exists.
      */
     public void addPerson(Person toAdd) throws DuplicatePersonException {
-        syncTagsWithMasterList(toAdd);
         allPersons.add(toAdd);
     }
 
@@ -99,11 +59,10 @@ public void removePerson(ReadOnlyPerson toRemove) throws PersonNotFoundException
     }
 
     /**
-     * Clears all persons and tags from the address book.
+     * Clears all persons from the address book.
      */
     public void clear() {
         allPersons.clear();
-        allTags.clear();
     }
 
     /**
@@ -113,24 +72,15 @@ public UniquePersonList getAllPersons() {
         return new UniquePersonList(allPersons);
     }
 
-    /**
-     * Defensively copied UniqueTagList of all tags in the address book at the time of the call.
-     */
-    public UniqueTagList getAllTags() {
-        return new UniqueTagList(allTags);
-    }
-
     @Override
     public boolean equals(Object other) {
         return other == this // short circuit if same object
                 || (other instanceof AddressBook // instanceof handles nulls
-                && this.allPersons.equals(((AddressBook) other).allPersons)
-                && this.allTags.equals(((AddressBook) other).allTags));
+                && this.allPersons.equals(((AddressBook) other).allPersons));
     }
 
     @Override
     public int hashCode() {
-        // use this method for custom fields hashing instead of implementing your own
-        return Objects.hash(allPersons, allTags);
+        return allPersons.hashCode();
     }
 }

src/seedu/addressbook/data/person/Person.java

@@ -1,8 +1,10 @@
 package seedu.addressbook.data.person;
 
-import seedu.addressbook.data.tag.UniqueTagList;
-
+import java.util.HashSet;
 import java.util.Objects;
+import java.util.Set;
+
+import seedu.addressbook.data.tag.Tag;
 
 /**
  * Represents a Person in the address book.
@@ -15,16 +17,16 @@ public class Person implements ReadOnlyPerson {
     private Email email;
     private Address address;
 
-    private final UniqueTagList tags;
+    private final Set<Tag> tags = new HashSet<>();
     /**
      * Assumption: Every field must be present and not null.
      */
-    public Person(Name name, Phone phone, Email email, Address address, UniqueTagList tags) {
+    public Person(Name name, Phone phone, Email email, Address address, Set<Tag> tags) {
         this.name = name;
         this.phone = phone;
         this.email = email;
         this.address = address;
-        this.tags = new UniqueTagList(tags); // protect internal tags from changes in the arg list
+        this.tags.addAll(tags);
     }
 
     /**
@@ -55,15 +57,16 @@ public Address getAddress() {
     }
 
     @Override
-    public UniqueTagList getTags() {
-        return new UniqueTagList(tags);
+    public Set<Tag> getTags() {
+        return new HashSet<>(tags);
     }
 
     /**
-     * Replaces this person's tags with the tags in the argument tag list.
+     * Replaces this person's tags with the tags in {@code replacement}.
      */
-    public void setTags(UniqueTagList replacement) {
-        tags.setTags(replacement);
+    public void setTags(Set<Tag> replacement) {
+        tags.clear();
+        tags.addAll(replacement);
     }
 
     @Override

src/seedu/addressbook/data/person/ReadOnlyPerson.java

@@ -1,7 +1,8 @@
 package seedu.addressbook.data.person;
 
+import java.util.Set;
+
 import seedu.addressbook.data.tag.Tag;
-import seedu.addressbook.data.tag.UniqueTagList;
 
 /**
  * A read-only immutable interface for a Person in the addressbook.
@@ -15,10 +16,10 @@ public interface ReadOnlyPerson {
     Address getAddress();
 
     /**
-     * The returned TagList is a deep copy of the internal TagList,
+     * The returned {@code Set} is a deep copy of the internal {@code Set},
      * changes on the returned list will not affect the person's internal tags.
      */
-    UniqueTagList getTags();
+    Set<Tag> getTags();
 
     /**
      * Returns true if the values inside this object is same as those of the other (Note: interfaces cannot override .equals)