Update DG with the find feature

docs/DeveloperGuide.md

@@ -190,8 +190,37 @@ Then, when the user inputs an instrument in the command, the `Instrument::isVali
   * Cons: The user can store invalid instruments and genres (due to typos) for a musician. This way, the user will encounter difficulties when finding musicians by instruments or genres.
 
 
-### Filtering Musicians by Name and Tags Feature
-To be Added.
+### Find Musician Feature
+
+The find musician feature allows the user to search for musicians by their name, general tags, instruments, and genres. The following activity diagram illustrates the logic flow of the feature.
+
+![FindMusicianActivityDiagram.png](images%2FFindMusicianActivityDiagram.png)
+
+As shown by the diagram, the find feature finds musicians who satisfy the matching criteria (matching at least one keyword) for _all_ specified categories. For example, if the user inputs `find n/John i/piano i/guitar g/jazz`, the find feature will return all musicians whose name contains `John` **and** plays the instrument `guitar` **or** `piano` **and** specialises in the genre `jazz`.
+
+#### Implementation
+
+The following sequence diagram explains in detail how the find feature works with an example scenario.
+
+![FindMusicianSequenceDiagram.png](images%2FFindMusicianSequenceDiagram.png)
+
+<div markdown="block" class="alert alert-info">
+
+:information_source: **Meanings of the abbreviations used in the diagram:**
+
+* `NCKP`: `NameContainsKeywordsPredicate`
+* `IMP`: `InstrumentMatchesPredicate`
+* `GMP`: `GenreMatchesPredicate`
+
+Abbreviations are used to reduce the clutter in the diagram.
+
+</div>
+
+Step 1. A `FindCommandParser` parses the command and creates a predicate for each category (`NCKP`, `IMP`, `GMP`) based on the keywords specified by the user. Since the user specifies nothing for the `tag` category, the `TagMatchesKeywordPredicate` is not created.
+
+Step 2. Then, the `FindCommndParser` creates a `FindCommand` object with the set of predicates created in the previous step.
+
+Step 3. When the `FindCommand` object is executed, it combines all the predicates into a single `combinedPrediacte`. This predicate is then used to filter the musician list using the `Model::updateFilteredMusicianList(Predicate)` method.
 
 ### Add Band Feature 
 The user can add a new Band entity to the storage through the `addb` Command.

docs/diagrams/FindMusicianActivityDiagram.puml

@@ -0,0 +1,33 @@
+@startuml
+skin rose
+skinparam ActivityFontSize 15
+skinparam ArrowFontSize 12
+skinparam defaultTextAlignment center
+
+start
+:User executes find command;
+:Parse the input keywords;
+
+'Since the beta syntax does not support placing the condition outside the
+'diamond we place it as the true branch instead.
+
+if () then ([input is invalid])
+    :Show corresponding error message;
+else ([else])
+    :Separate the keywords into categories
+    (name, tag, instrument, and genre);
+    while () is ([else])
+        :Go to the next category;
+        if () then ([the category is empty])
+            :Skip this category;
+        else ([else])
+            :Filter the musicians who
+            match ANY of the keywords
+            in this category;
+        endif
+    endwhile ([all categories are checked])
+    :Return the musicians who pass ALL filters;
+endif
+
+stop
+@enduml

docs/diagrams/FindMusicianSequenceDiagram.puml

@@ -0,0 +1,91 @@
+@startuml
+!include style.puml
+skinparam ArrowFontStyle plain
+
+box Logic LOGIC_COLOR_T1
+participant ":AddressBookParser" as AddressBookParser LOGIC_COLOR
+participant ":FindCommandParser" as FindCommandParser LOGIC_COLOR
+participant "f:FindCommand" as FindCommand LOGIC_COLOR
+participant ":CommandResult" as CommandResult LOGIC_COLOR
+end box
+
+box Model MODEL_COLOR_T1
+participant ":Model" as Model MODEL_COLOR
+participant ":NCKP" as NameContainsKeywordsPredicate MODEL_COLOR
+participant ":IMP" as InstrumentMatchesPredicate MODEL_COLOR
+participant ":GMP" as GenreMatchesPredicate MODEL_COLOR
+end box
+
+[-> AddressBookParser : parseCommand\n("find n/John i/piano i/guitar g/jazz")
+activate AddressBookParser
+
+create FindCommandParser
+AddressBookParser -> FindCommandParser
+activate FindCommandParser
+
+FindCommandParser --> AddressBookParser
+deactivate FindCommandParser
+
+AddressBookParser -> FindCommandParser : parse\n("n/John i/piano i/guitar g/jazz")
+activate FindCommandParser
+
+create NameContainsKeywordsPredicate
+FindCommandParser -> NameContainsKeywordsPredicate : NameContainsKeywordsPredicate(List.of("John"))
+activate NameContainsKeywordsPredicate
+
+NameContainsKeywordsPredicate --> FindCommandParser
+deactivate NameContainsKeywordsPredicate
+
+create InstrumentMatchesPredicate
+FindCommandParser -> InstrumentMatchesPredicate : InstrumentMatchesPredicate(List.of("piano", "guitar"))
+activate InstrumentMatchesPredicate
+
+InstrumentMatchesPredicate --> FindCommandParser
+deactivate InstrumentMatchesPredicate
+
+create GenreMatchesPredicate
+FindCommandParser -> GenreMatchesPredicate : GenreMatchesPredicate(List.of("jazz"))
+activate GenreMatchesPredicate
+
+GenreMatchesPredicate --> FindCommandParser
+deactivate GenreMatchesPredicate
+
+create FindCommand
+FindCommandParser -> FindCommand : pass the set of predicates
+activate FindCommand
+
+FindCommand --> FindCommandParser : f
+deactivate FindCommand
+
+FindCommandParser --> AddressBookParser : f
+deactivate FindCommandParser
+'Hidden arrow to position the destroy marker below the end of the activation bar.
+FindCommandParser -[hidden]-> AddressBookParser
+destroy FindCommandParser
+
+[<-- AddressBookParser : f
+deactivate AddressBookParser
+
+[-> FindCommand : execute()
+activate FindCommand
+
+FindCommand -> Model : updateFilteredMusicianList\n(combinedPredicates)
+activate Model
+
+'Hidden arrow to increase the length of the activation bar.
+Model -[hidden]-> Model
+
+Model --> FindCommand
+deactivate Model
+
+create CommandResult
+FindCommand -> CommandResult
+activate CommandResult
+
+CommandResult --> FindCommand
+deactivate CommandResult
+
+[<-- FindCommand : result
+deactivate FindCommand
+
+@enduml