Optimisations: Don't keep saving state when you continually see the s…

…ame newline during a calculation after a line of content. Avoid allocating continually in VisitChangedContainersDueToDivert. Cache output stream contents.

ink-engine-runtime/Story.cs

@@ -302,7 +302,13 @@ string ContinueInternal()
                             // We're going to continue stepping in case we see glue or some
                             // non-text content such as choices.
                             if( canContinue ) {
-                                stateAtLastNewline = StateSnapshot();
+
+								// Don't bother to record the state beyond the current newline.
+								// e.g.:
+								// Hello world\n			// record state at the end of here
+								// ~ complexCalculation()   // don't actually need this unless it generates text
+								if( stateAtLastNewline == null )
+                                	stateAtLastNewline = StateSnapshot();
                             } 
 
                             // Can't continue, so we're about to exit - make sure we
@@ -510,6 +516,7 @@ void VisitContainer(Container container, bool atStart)
             }
         }
 
+		HashSet<Container> _prevContainerSet;
         void VisitChangedContainersDueToDivert()
         {
             var previousContentObject = state.previousContentObject;
@@ -519,11 +526,12 @@ void VisitChangedContainersDueToDivert()
                 return;
 
             // First, find the previously open set of containers
-            var prevContainerSet = new HashSet<Container> ();
+			if( _prevContainerSet == null ) _prevContainerSet = new HashSet<Container> ();
+			_prevContainerSet.Clear();
             if (previousContentObject) {
                 Container prevAncestor = previousContentObject as Container ?? previousContentObject.parent as Container;
                 while (prevAncestor) {
-                    prevContainerSet.Add (prevAncestor);
+					_prevContainerSet.Add (prevAncestor);
                     prevAncestor = prevAncestor.parent as Container;
                 }
             }
@@ -532,7 +540,7 @@ void VisitChangedContainersDueToDivert()
             // content step. However, we need to walk up the new ancestry to see if there are more new containers
             Runtime.Object currentChildOfContainer = newContentObject;
             Container currentContainerAncestor = currentChildOfContainer.parent as Container;
-            while (currentContainerAncestor && !prevContainerSet.Contains(currentContainerAncestor)) {
+			while (currentContainerAncestor && !_prevContainerSet.Contains(currentContainerAncestor)) {
 
                 // Check whether this ancestor container is being entered at the start,
                 // by checking whether the child object is the first.

ink-engine-runtime/StoryState.cs

@@ -147,35 +147,47 @@ internal string currentText
         {
             get 
             {
-                var sb = new StringBuilder ();
+				if( _outputStreamTextDirty ) {
+					var sb = new StringBuilder ();
+
+					foreach (var outputObj in _outputStream) {
+						var textContent = outputObj as StringValue;
+						if (textContent != null) {
+							sb.Append(textContent.value);
+						}
+					}
 
-                foreach (var outputObj in _outputStream) {
-                    var textContent = outputObj as StringValue;
-                    if (textContent != null) {
-                        sb.Append(textContent.value);
-                    }
-                }
+					_currentText = sb.ToString ();
+
+					_outputStreamTextDirty = false;
+				}
 
-                return sb.ToString ();
+				return _currentText;
             }
         }
+		string _currentText;
 
         internal List<string> currentTags 
         {
             get 
             {
-                List<string> tags = new List<string>();
+				if( _outputStreamTagsDirty ) {
+					_currentTags = new List<string>();
+
+					foreach (var outputObj in _outputStream) {
+						var tag = outputObj as Tag;
+						if (tag != null) {
+							_currentTags.Add (tag.text);
+						}
+					}
 
-                foreach (var outputObj in _outputStream) {
-                    var tag = outputObj as Tag;
-                    if (tag != null) {
-                        tags.Add (tag.text);
-                    }
-                }
+					_outputStreamTagsDirty = false;
+				}
 
-                return tags;
+				return _currentTags;
             }
         }
+		List<string> _currentTags;
 
         internal bool inExpressionEvaluation {
             get {
@@ -191,6 +203,7 @@ internal StoryState (Story story)
             this.story = story;
 
             _outputStream = new List<Runtime.Object> ();
+			OutputStreamDirty();
 
             evaluationStack = new List<Runtime.Object> ();
 
@@ -227,6 +240,8 @@ internal StoryState Copy()
             var copy = new StoryState(story);
 
             copy.outputStream.AddRange(_outputStream);
+			OutputStreamDirty();
+
 			copy._currentChoices.AddRange(_currentChoices);
 
             if (hasError) {
@@ -328,6 +343,7 @@ public Dictionary<string, object> jsonToken
                 evaluationStack = Json.JArrayToRuntimeObjList ((List<object>)jObject ["evalStack"]);
 
                 _outputStream = Json.JArrayToRuntimeObjList ((List<object>)jObject ["outputStream"]);
+				OutputStreamDirty();
 
 				_currentChoices = Json.JArrayToRuntimeObjList<Choice>((List<object>)jObject ["currentChoices"]);
 
@@ -370,6 +386,7 @@ internal void ResetErrors()
         internal void ResetOutput()
         {
             _outputStream.Clear ();
+			OutputStreamDirty();
         }
 
         // Push to output stream, but split out newlines in text for consistency
@@ -388,6 +405,8 @@ internal void PushToOutputStream(Runtime.Object obj)
             }
 
             PushToOutputStreamIndividual (obj);
+
+			OutputStreamDirty();
         }
 
 
@@ -523,6 +542,8 @@ void PushToOutputStreamIndividual(Runtime.Object obj)
             if (includeInOutput) {
                 _outputStream.Add (obj);
             }
+
+			OutputStreamDirty();
         }
 
         void TrimNewlinesFromOutputStream(Glue rightGlueToStopAt)
@@ -582,6 +603,8 @@ void TrimNewlinesFromOutputStream(Glue rightGlueToStopAt)
                     }
                 }
             }
+
+			OutputStreamDirty();
         }
 
         void TrimFromExistingGlue()
@@ -594,6 +617,8 @@ void TrimFromExistingGlue()
                 else
                     i++;
             }
+
+			OutputStreamDirty();
         }
 
 
@@ -608,6 +633,8 @@ void RemoveExistingGlue()
                     break;
                 }
             }
+
+			OutputStreamDirty();
         }
 
         int currentGlueIndex {
@@ -832,11 +859,20 @@ internal void AddError(string message)
             currentErrors.Add (message);
         }
 
+		void OutputStreamDirty()
+		{
+			_outputStreamTextDirty = true;
+			_outputStreamTagsDirty = true;
+		}
+
         // REMEMBER! REMEMBER! REMEMBER!
         // When adding state, update the Copy method and serialisation
         // REMEMBER! REMEMBER! REMEMBER!
 
         List<Runtime.Object> _outputStream;
+		bool _outputStreamTextDirty = true;
+		bool _outputStreamTagsDirty = true;
+
 		List<Choice> _currentChoices;
 
         // Temporary state only, during externally called function evaluation

tests/Tests.cs

@@ -2231,7 +2231,7 @@ public void TestVisitCountsWhenChoosing()
                 @"
 == TestKnot ==
 this is a test
-+ Next -> TestKnot2
++ [Next] -> TestKnot2
 
 == TestKnot2 ==
 this is the end