AddressBook: remove master tag list

We keep track of a master tag list which holds all the tags in our
address book.

The tag list is not used at all. The original intention was for
persons; tags to point to the tags in the master tag list. However,
implementing it in this way may be too complex for new developers to
grasp, as discussed in se-edu#753. Furthermore, from the discussion in se-edu#794,
the tag list in its current state is not needed.

Let's remove the master tag list in AddressBook.

src/main/java/seedu/address/commons/events/model/AddressBookChangedEvent.java

@@ -14,6 +14,6 @@ public AddressBookChangedEvent(ReadOnlyAddressBook data) {
 
     @Override
     public String toString() {
-        return "number of persons " + data.getPersonList().size() + ", number of tags " + data.getTagList().size();
+        return "number of persons " + data.getPersonList().size();
     }
 }

src/main/java/seedu/address/model/AddressBook.java

@@ -2,21 +2,13 @@
 
 import static java.util.Objects.requireNonNull;
 
-import java.util.HashMap;
-import java.util.HashSet;
 import java.util.List;
-import java.util.Map;
-import java.util.Objects;
-import java.util.Set;
-import java.util.stream.Collectors;
 
 import javafx.collections.ObservableList;
 import seedu.address.model.person.Person;
 import seedu.address.model.person.UniquePersonList;
 import seedu.address.model.person.exceptions.DuplicatePersonException;
 import seedu.address.model.person.exceptions.PersonNotFoundException;
-import seedu.address.model.tag.Tag;
-import seedu.address.model.tag.UniqueTagList;
 
 /**
  * Wraps all data at the address-book level
@@ -25,7 +17,6 @@
 public class AddressBook implements ReadOnlyAddressBook {
 
     private final UniquePersonList persons;
-    private final UniqueTagList tags;
 
     /*
      * The 'unusual' code block below is an non-static initialization block, sometimes used to avoid duplication
@@ -36,13 +27,12 @@ public class AddressBook implements ReadOnlyAddressBook {
      */
     {
         persons = new UniquePersonList();
-        tags = new UniqueTagList();
     }
 
     public AddressBook() {}
 
     /**
-     * Creates an AddressBook using the Persons and Tags in the {@code toBeCopied}
+     * Creates an AddressBook using the Persons in the {@code toBeCopied}
      */
     public AddressBook(ReadOnlyAddressBook toBeCopied) {
         this();
@@ -55,22 +45,14 @@ public void setPersons(List<Person> persons) throws DuplicatePersonException {
         this.persons.setPersons(persons);
     }
 
-    public void setTags(Set<Tag> tags) {
-        this.tags.setTags(tags);
-    }
-
     /**
      * Resets the existing data of this {@code AddressBook} with {@code newData}.
      */
     public void resetData(ReadOnlyAddressBook newData) {
         requireNonNull(newData);
-        setTags(new HashSet<>(newData.getTagList()));
-        List<Person> syncedPersonList = newData.getPersonList().stream()
-                .map(this::syncWithMasterTagList)
-                .collect(Collectors.toList());
 
         try {
-            setPersons(syncedPersonList);
+            setPersons(newData.getPersonList());
         } catch (DuplicatePersonException e) {
             throw new AssertionError("AddressBooks should not have duplicate persons");
         }
@@ -80,59 +62,25 @@ public void resetData(ReadOnlyAddressBook newData) {
 
     /**
      * Adds a person to the address book.
-     * Also checks the new person's tags and updates {@link #tags} with any new tags found,
-     * and updates the Tag objects in the person to point to those in {@link #tags}.
      *
      * @throws DuplicatePersonException if an equivalent person already exists.
      */
     public void addPerson(Person p) throws DuplicatePersonException {
-        Person person = syncWithMasterTagList(p);
-        // TODO: the tags master list will be updated even though the below line fails.
-        // This can cause the tags master list to have additional tags that are not tagged to any person
-        // in the person list.
-        persons.add(person);
+        persons.add(p);
     }
 
     /**
      * Replaces the given person {@code target} in the list with {@code editedPerson}.
-     * {@code AddressBook}'s tag list will be updated with the tags of {@code editedPerson}.
      *
      * @throws DuplicatePersonException if updating the person's details causes the person to be equivalent to
      *      another existing person in the list.
      * @throws PersonNotFoundException if {@code target} could not be found in the list.
-     *
-     * @see #syncWithMasterTagList(Person)
      */
     public void updatePerson(Person target, Person editedPerson)
             throws DuplicatePersonException, PersonNotFoundException {
         requireNonNull(editedPerson);
 
-        Person syncedEditedPerson = syncWithMasterTagList(editedPerson);
-        // TODO: the tags master list will be updated even though the below line fails.
-        // This can cause the tags master list to have additional tags that are not tagged to any person
-        // in the person list.
-        persons.setPerson(target, syncedEditedPerson);
-    }
-
-    /**
-     *  Updates the master tag list to include tags in {@code person} that are not in the list.
-     *  @return a copy of this {@code person} such that every tag in this person points to a Tag object in the master
-     *  list.
-     */
-    private Person syncWithMasterTagList(Person person) {
-        final UniqueTagList personTags = new UniqueTagList(person.getTags());
-        tags.mergeFrom(personTags);
-
-        // Create map with values = tag object references in the master list
-        // used for checking person tag references
-        final Map<Tag, Tag> masterTagObjects = new HashMap<>();
-        tags.forEach(tag -> masterTagObjects.put(tag, tag));
-
-        // Rebuild the list of person tags to point to the relevant tags in the master tag list.
-        final Set<Tag> correctTagReferences = new HashSet<>();
-        personTags.forEach(tag -> correctTagReferences.add(masterTagObjects.get(tag)));
-        return new Person(
-                person.getName(), person.getPhone(), person.getEmail(), person.getAddress(), correctTagReferences);
+        persons.setPerson(target, editedPerson);
     }
 
     /**
@@ -143,17 +91,11 @@ public void removePerson(Person key) throws PersonNotFoundException {
         persons.remove(key);
     }
 
-    //// tag-level operations
-
-    public void addTag(Tag t) throws UniqueTagList.DuplicateTagException {
-        tags.add(t);
-    }
-
     //// util methods
 
     @Override
     public String toString() {
-        return persons.asObservableList().size() + " persons, " + tags.asObservableList().size() +  " tags";
+        return persons.asObservableList().size() + " persons";
         // TODO: refine later
     }
 
@@ -162,22 +104,15 @@ public ObservableList<Person> getPersonList() {
         return persons.asObservableList();
     }
 
-    @Override
-    public ObservableList<Tag> getTagList() {
-        return tags.asObservableList();
-    }
-
     @Override
     public boolean equals(Object other) {
         return other == this // short circuit if same object
                 || (other instanceof AddressBook // instanceof handles nulls
-                && this.persons.equals(((AddressBook) other).persons)
-                && this.tags.equalsOrderInsensitive(((AddressBook) other).tags));
+                && this.persons.equals(((AddressBook) other).persons));
     }
 
     @Override
     public int hashCode() {
-        // use this method for custom fields hashing instead of implementing your own
-        return Objects.hash(persons, tags);
+        return persons.hashCode();
     }
 }

src/main/java/seedu/address/model/ReadOnlyAddressBook.java

@@ -2,7 +2,6 @@
 
 import javafx.collections.ObservableList;
 import seedu.address.model.person.Person;
-import seedu.address.model.tag.Tag;
 
 /**
  * Unmodifiable view of an address book
@@ -15,10 +14,4 @@ public interface ReadOnlyAddressBook {
      */
     ObservableList<Person> getPersonList();
 
-    /**
-     * Returns an unmodifiable view of the tags list.
-     * This list will not contain any duplicate tags.
-     */
-    ObservableList<Tag> getTagList();
-
 }

src/test/java/seedu/address/model/AddressBookTest.java

@@ -4,7 +4,6 @@
 import static seedu.address.testutil.TypicalPersons.ALICE;
 import static seedu.address.testutil.TypicalPersons.getTypicalAddressBook;
 
-import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
@@ -17,7 +16,6 @@
 import javafx.collections.FXCollections;
 import javafx.collections.ObservableList;
 import seedu.address.model.person.Person;
-import seedu.address.model.tag.Tag;
 
 public class AddressBookTest {
 
@@ -29,7 +27,6 @@ public class AddressBookTest {
     @Test
     public void constructor() {
         assertEquals(Collections.emptyList(), addressBook.getPersonList());
-        assertEquals(Collections.emptyList(), addressBook.getTagList());
     }
 
     @Test
@@ -49,8 +46,7 @@ public void resetData_withValidReadOnlyAddressBook_replacesData() {
     public void resetData_withDuplicatePersons_throwsAssertionError() {
         // Repeat ALICE twice
         List<Person> newPersons = Arrays.asList(ALICE, ALICE);
-        List<Tag> newTags = new ArrayList<>(ALICE.getTags());
-        AddressBookStub newData = new AddressBookStub(newPersons, newTags);
+        AddressBookStub newData = new AddressBookStub(newPersons);
 
         thrown.expect(AssertionError.class);
         addressBook.resetData(newData);
@@ -62,33 +58,20 @@ public void getPersonList_modifyList_throwsUnsupportedOperationException() {
         addressBook.getPersonList().remove(0);
     }
 
-    @Test
-    public void getTagList_modifyList_throwsUnsupportedOperationException() {
-        thrown.expect(UnsupportedOperationException.class);
-        addressBook.getTagList().remove(0);
-    }
-
     /**
-     * A stub ReadOnlyAddressBook whose persons and tags lists can violate interface constraints.
+     * A stub ReadOnlyAddressBook whose persons list can violate interface constraints.
      */
     private static class AddressBookStub implements ReadOnlyAddressBook {
         private final ObservableList<Person> persons = FXCollections.observableArrayList();
-        private final ObservableList<Tag> tags = FXCollections.observableArrayList();
 
-        AddressBookStub(Collection<Person> persons, Collection<? extends Tag> tags) {
+        AddressBookStub(Collection<Person> persons) {
             this.persons.setAll(persons);
-            this.tags.setAll(tags);
         }
 
         @Override
         public ObservableList<Person> getPersonList() {
             return persons;
         }
-
-        @Override
-        public ObservableList<Tag> getTagList() {
-            return tags;
-        }
     }
 
 }

src/test/java/seedu/address/testutil/AddressBookBuilder.java

@@ -1,15 +1,13 @@
 package seedu.address.testutil;
 
-import seedu.address.commons.exceptions.IllegalValueException;
 import seedu.address.model.AddressBook;
 import seedu.address.model.person.Person;
 import seedu.address.model.person.exceptions.DuplicatePersonException;
-import seedu.address.model.tag.Tag;
 
 /**
  * A utility class to help with building Addressbook objects.
  * Example usage: <br>
- *     {@code AddressBook ab = new AddressBookBuilder().withPerson("John", "Doe").withTag("Friend").build();}
+ *     {@code AddressBook ab = new AddressBookBuilder().withPerson("John", "Doe").build();}
  */
 public class AddressBookBuilder {
 
@@ -35,18 +33,6 @@ public AddressBookBuilder withPerson(Person person) {
         return this;
     }
 
-    /**
-     * Parses {@code tagName} into a {@code Tag} and adds it to the {@code AddressBook} that we are building.
-     */
-    public AddressBookBuilder withTag(String tagName) {
-        try {
-            addressBook.addTag(new Tag(tagName));
-        } catch (IllegalValueException ive) {
-            throw new IllegalArgumentException("tagName is expected to be valid.");
-        }
-        return this;
-    }
-
     public AddressBook build() {
         return addressBook;
     }