[Java] Generate check that encoding is complete.

Previously, we checked the order of encoding was correct but not that
the encoding reached a terminal state.

In this commit, I've added code to generate a new method
`checkEncodingIsComplete` on Java encoders. It verifies that a terminal
state has been reached; otherwise, it throws an exception with
information about the current state and transitions.

Author: ZachBray

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/java/AccessOrderModel.java

@@ -48,6 +48,7 @@ final class AccessOrderModel
     private final Int2ObjectHashMap<State> versionWrappedStates = new Int2ObjectHashMap<>();
     private final State notWrappedState = allocateState("NOT_WRAPPED");
     private State encoderWrappedState;
+    private Set<State> terminalEncoderStates;
 
     static boolean generateAccessOrderChecks()
     {
@@ -86,6 +87,11 @@ void forEachDecoderWrappedState(final IntObjConsumer<State> consumer)
         }
     }
 
+    void forEachTerminalEncoderState(final Consumer<State> consumer)
+    {
+        terminalEncoderStates.forEach(consumer);
+    }
+
     void forEachStateOrderedByStateNumber(final Consumer<State> consumer)
     {
         transitionsByState.keySet().stream()
@@ -165,8 +171,6 @@ private void findTransitions(
 
             versionWrappedStates.put(version, versionWrappedState);
 
-            encoderWrappedState = versionWrappedState;
-
             final CodecInteraction wrapInteraction = interactionFactory.wrap(version);
 
             allocateTransitions(
@@ -183,6 +187,10 @@ private void findTransitions(
             );
 
             walkSchemaLevel(transitionCollector, fields, groups, varData);
+
+            // Last writer (highest version) wins when there are multiple versions
+            encoderWrappedState = versionWrappedState;
+            terminalEncoderStates = transitionCollector.exitStates();
         });
     }
 

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/java/JavaGenerator.java

@@ -273,6 +273,7 @@ private void generateEncoder(
             generateEncoderVarData(sb, className, accessOrderModel, varData, BASE_INDENT);
 
             generateEncoderDisplay(sb, decoderName(msgToken.name()));
+            generateFullyEncodedCheck(sb, accessOrderModel);
 
             out.append(sb);
             out.append("}\n");
@@ -395,6 +396,36 @@ private static CharSequence generateFieldOrderStates(final AccessOrderModel acce
         return sb;
     }
 
+    private static void generateFullyEncodedCheck(
+        final StringBuilder sb,
+        final AccessOrderModel accessOrderModel)
+    {
+        if (null == accessOrderModel)
+        {
+            return;
+        }
+
+        sb.append("\n");
+
+        sb.append("    public void checkEncodingIsComplete()\n")
+            .append("    {\n")
+            .append("        switch (codecState)\n")
+            .append("        {\n");
+
+        accessOrderModel.forEachTerminalEncoderState(state ->
+        {
+            sb.append("            case ").append(stateCaseForSwitchCase(state)).append(":\n")
+                .append("                return;\n");
+        });
+
+        sb.append("            default:\n")
+            .append("                throw new IllegalStateException(\"Not fully encoded, current state: \" +\n")
+            .append("                    CodecStates.name(codecState) + \", allowed transitions: \" +\n")
+            .append("                    CodecStates.transitions(codecState));\n")
+            .append("        }\n")
+            .append("    }\n\n");
+    }
+
     private static String accessOrderListenerMethodName(final Token token)
     {
         return "on" + Generators.toUpperFirstChar(token.name()) + "Accessed";

sbe-tool/src/main/java/uk/co/real_logic/sbe/ir/generated/FrameCodecEncoder.java

@@ -728,4 +728,18 @@ public StringBuilder appendTo(final StringBuilder builder)
 
         return decoder.appendTo(builder);
     }
+
+    public void checkEncodingIsComplete()
+    {
+        switch (codecState)
+        {
+            case CodecStates.V0_SEMANTICVERSION_DONE:
+                return;
+            default:
+                throw new IllegalStateException("Not fully encoded, current state: " +
+                    CodecStates.name(codecState) + ", allowed transitions: " +
+                    CodecStates.transitions(codecState));
+        }
+    }
+
 }

sbe-tool/src/main/java/uk/co/real_logic/sbe/ir/generated/TokenCodecEncoder.java

@@ -2027,4 +2027,18 @@ public StringBuilder appendTo(final StringBuilder builder)
 
         return decoder.appendTo(builder);
     }
+
+    public void checkEncodingIsComplete()
+    {
+        switch (codecState)
+        {
+            case CodecStates.V0_REFERENCEDNAME_DONE:
+                return;
+            default:
+                throw new IllegalStateException("Not fully encoded, current state: " +
+                    CodecStates.name(codecState) + ", allowed transitions: " +
+                    CodecStates.transitions(codecState));
+        }
+    }
+
 }