Add Java equality and hash functions to events and machines in pobserve mode

Generate deepEquals(), equals(), and hashCode() methods in the Java code for
events and machines when compiled in pobserve mode.

Author: lewisbru

Src/PCompiler/CompilerCore/Backend/Java/EventGenerator.cs

@@ -78,6 +78,45 @@ private void WriteEventDecl(Event e)
                 WriteLine($" return \"{eventName}\"; }}");
             }
 
+            WriteLine();
+            Write("public int hashCode() {");
+            if (hasPayload)
+            {
+                WriteLine(" return payload.hashCode(); }");
+            }
+            else
+            {
+                WriteLine(" return 0; }");
+            }
+
+            WriteLine();
+            Write($"public boolean deepEquals({eventName} other) {{");
+            if (hasPayload)
+            {
+                if (argType.IsPrimitive)
+                {
+                    WriteLine(" return this.payload == other.payload; }");
+                }
+                else
+                {
+                    WriteLine($" return {Constants.PrtDeepEqualsMethodName}(this.payload, other.payload); }}");
+                }
+            }
+            else
+            {
+                WriteLine("return true; }");
+            }
+
+            WriteLine();
+            WriteLine("public boolean equals(Object other) {");
+            Write("return this.getClass() == other.getClass()");
+            if (hasPayload)
+            {
+                Write($" && this.payload.deepEquals((({eventName})other).payload)");
+            }
+            WriteLine(";");
+            WriteLine("}");
+
             WriteLine($"}} // {eventName}");
         }
     }

Src/PCompiler/CompilerCore/Backend/Java/MachineGenerator.cs

@@ -83,11 +83,7 @@ private void WriteMonitorDecl()
             WriteLine();
 
             // monitor fields
-            foreach (var field in _currentMachine.Fields)
-            {
-                var type = Types.JavaTypeFor(field.Type);
-                var name = Names.GetNameForDecl(field);
-
+            foreach (var (type, name) in FieldsForCurrentMachine()) {
                 WriteLine($"private {type.TypeName} {name} = {type.DefaultValue};");
                 WriteLine($"public {type.TypeName} get_{name}() {{ return this.{name}; }};");
                 WriteLine();
@@ -118,7 +114,7 @@ private void WriteMonitorDecl()
                 WriteFunction(f);
             }
 
-            WriteToString();
+            WriteOverloads();
 
             WriteLine();
 
@@ -967,21 +963,59 @@ private void WriteStructureAccess(IPExpr e)
             }
         }
 
-        private void WriteToString()
+        private void WriteOverloads()
         {
+            // toString()
+            WriteLine();
             WriteLine("public String toString() {");
             WriteLine($"StringBuilder sb = new StringBuilder(\"{_currentMachine.Name}\");");
-            
+
             WriteLine("sb.append(\"[\");");
             foreach (var (sep, field) in _currentMachine.Fields.WithPrefixSep(", "))
             {
                 WriteLine($"sb.append(\"{sep}{field.Name}=\" + {Names.GetNameForDecl(field)});");
             }
+
             WriteLine("sb.append(\"]\");");
-            
+
             WriteLine("return sb.toString();");
             WriteLine("} // toString()");
+
+            // deepEquals
+            WriteLine();
+            WriteLine($"public boolean deepEquals({_currentMachine.Name} other) {{");
+            WriteLine("return (true");
+            foreach (var (jType, fieldName) in FieldsForCurrentMachine())
+            {
+                Write("&& ");
+                WriteLine(jType.IsPrimitive
+                    ? $"this.{fieldName} == other.{fieldName}"
+                    : $"{Constants.PrtDeepEqualsMethodName}(this.{fieldName}, other.{fieldName})");
+            }
+            WriteLine(");");
+            WriteLine("} // deepEquals()");
+
+            // equals
+            WriteLine();
+            WriteLine("public boolean equals(Object other) {");
+            WriteLine($"return (this.getClass() == other.getClass()) && this.deepEquals(({_currentMachine.Name})other);");
+            WriteLine("} // equals()");
+
+            // hashCode
+            WriteLine();
+            WriteLine("public int hashCode() {");
+            Write("return Objects.hash(");
+            foreach (var (sep, (_, fieldName)) in FieldsForCurrentMachine().WithPrefixSep(", "))
+            {
+                Write($"{sep}{fieldName}");
+            }
+            WriteLine(");");
+            WriteLine("} // hashCode()");
+        }
+
+        private IEnumerable<(TypeManager.JType, string)> FieldsForCurrentMachine()
+        {
+            return _currentMachine.Fields.Select(field => (Types.JavaTypeFor(field.Type), Names.GetNameForDecl(field)));
         }
-        
     }
 }