Add class diagram for find command

docs/DeveloperGuide.md

@@ -370,7 +370,7 @@ In this section, we focus only on `FindCommand`, which is strictly the more comp
 
 The following class diagram shows all classes involved:
 
-CLASS DIAGRAM GOES HERE
+![FindCommandClassDiagram.png](images/FindCommandClassDiagram.png)
 
 To illustrate how everything works together, we trace the flow of execution as the user searches for `Tom / Sam`. Details involving `MainWindow` and `LogicManager` are ignored, especially since they are common across all commands. 
 
@@ -386,6 +386,9 @@ Step 5. `FindCommand` calls `updateFilteredPersonList` of the `Model`, which ref
 
 Step 6. The `list` command stops here, and execution is returned to the `LogicManager`, and then `MainWindow`. The `MainWindow` shows text feedback, together with the updated list of fosterers.
 
+
+The following diagram ignores details for `SearchPredicate`, which will be covered shortly: 
+
 ![FindCommandSequenceDiagram.png](images/FindCommandSequenceDiagram.png)
 
 

docs/diagrams/FindCommandClassDiagram.puml

@@ -0,0 +1,44 @@
+@startuml
+!include style.puml
+skinparam arrowThickness 1.1
+skinparam classBackgroundColor UI_COLOR
+
+package search <<Rectangle>> {
+    Class FindCommandArgumentParser
+    Class SearchPredicate
+    Class "{abstract}\nSearchMatcher" as SearchMatcher
+    Class "{abstract}\nBinarySearchMatcher" as BinarySearchMatcher
+    Class AndSearchMatcher
+    Class OrSearchMatcher
+    Class NotSearchMatcher
+    Class SingleTextSearchMatcher
+    Class FieldRanges
+    Class Range
+}
+
+package parser <<Rectangle>> {
+    Class FindCommandParser
+}
+
+package commands <<Rectangle>> {
+    Class FindCommand
+}
+
+FindCommandParser .> FindCommandArgumentParser
+FindCommandParser .> FindCommand
+FindCommandArgumentParser .> SearchPredicate
+
+FindCommand *--> SearchPredicate
+SearchPredicate *--> SearchMatcher
+
+FieldRanges *-right-> Range
+
+SearchMatcher .> FieldRanges
+SearchMatcher <|-- BinarySearchMatcher
+SearchMatcher <|-- SingleTextSearchMatcher
+SearchMatcher <|-- NotSearchMatcher
+
+BinarySearchMatcher <|-- AndSearchMatcher
+BinarySearchMatcher <|-- OrSearchMatcher
+
+@enduml