Bug fixes to conditional GCode

Fixed premature termination of a loop when there were not commands in
the file after the loop body
Fixed crash when you tried to access a missong element of a sparse
object array
Handle stringising of null and object values (but objects are
represented as "{object}" for now)

2 files changed, 18 insertions, 13 deletions

diff --git a/src/ObjectModel/ObjectModel.cpp b/src/ObjectModel/ObjectModel.cpp
index ba581ddd..0b05f749 100644
--- a/src/ObjectModel/ObjectModel.cpp
+++ b/src/ObjectModel/ObjectModel.cpp
@@ -293,16 +293,11 @@ void ObjectModel::ReportItemAsJson(OutputBuffer *buf, ObjectExplorationContext&
 			break;
 
 		case TYPE_OF(const ObjectModel*):
-			if (val.omVal != nullptr)
+			if (*filter == '.')
 			{
-				if (*filter == '.')
-				{
-					++filter;
-				}
-				return val.omVal->ReportAsJson(buf, context, val.param, filter);
+				++filter;
 			}
-			buf->cat("null");
-			break;
+			return val.omVal->ReportAsJson(buf, context, val.param, filter);
 
 		case TYPE_OF(float):
 			if (val.fVal == 0.0)
@@ -653,15 +648,25 @@ ExpressionValue ObjectModel::GetObjectValue(ObjectExplorationContext& context, E
 		}
 
 	case TYPE_OF(const ObjectModel*):
-		if (*idString == '.')
+		switch (*idString)
 		{
+		case 0:
+			return val;
+		case '.':
 			return val.omVal->GetObjectValue(context, idString + 1, val.param);
+		case '^':
+			throw context.ConstructParseException("object is not an array");
+		default:
+			throw context.ConstructParseException("syntax error in object model path");
 		}
+		break;
+
+	case NoType:
 		if (*idString == 0)
 		{
-			return val;				// an object value can be compared to null
+			return val;				// a null value can be compared to null
 		}
-		throw context.ConstructParseException((*idString == '[') ? "object is not an array" : "syntax error in object model path");
+		throw context.ConstructParseException("reached null object before end of selector string");
 
 	case TYPE_OF(Bitmap<uint16_t>):
 	case TYPE_OF(Bitmap<uint32_t>):
diff --git a/src/ObjectModel/ObjectModel.h b/src/ObjectModel/ObjectModel.h
index 0b60ef33..ed5270c2 100644
--- a/src/ObjectModel/ObjectModel.h
+++ b/src/ObjectModel/ObjectModel.h
@@ -103,8 +103,8 @@ struct ExpressionValue
 	explicit constexpr ExpressionValue(float f) noexcept : type(TYPE_OF(float)), param(MaxFloatDigitsDisplayedAfterPoint), fVal(f) { }
 	constexpr ExpressionValue(float f, uint8_t numDecimalPlaces) noexcept : type(TYPE_OF(float)), param(numDecimalPlaces), fVal(f) { }
 	explicit constexpr ExpressionValue(int32_t i) noexcept : type(TYPE_OF(int32_t)), param(0), iVal(i) { }
-	explicit constexpr ExpressionValue(const ObjectModel *om) noexcept : type(TYPE_OF(const ObjectModel*)), param(0), omVal(om) { }
-	constexpr ExpressionValue(const ObjectModel *om, uint8_t tableNumber) noexcept : type(TYPE_OF(const ObjectModel*)), param(tableNumber), omVal(om) { }
+	explicit constexpr ExpressionValue(const ObjectModel *om) noexcept : type((om == nullptr) ? NoType : TYPE_OF(const ObjectModel*)), param(0), omVal(om) { }
+	constexpr ExpressionValue(const ObjectModel *om, uint8_t tableNumber) noexcept : type((om == nullptr) ? NoType : TYPE_OF(const ObjectModel*)), param(tableNumber), omVal(om) { }
 	explicit constexpr ExpressionValue(const char *s) noexcept : type(TYPE_OF(const char*)), param(0), sVal(s) { }
 	explicit constexpr ExpressionValue(const ObjectModelArrayDescriptor *omad) noexcept : type(TYPE_OF(const ObjectModelArrayDescriptor*)), param(0), omadVal(omad) { }
 	explicit constexpr ExpressionValue(IPAddress ip) noexcept : type(TYPE_OF(IPAddress)), param(0), uVal(ip.GetV4LittleEndian()) { }