Add domain specifier to variable declarations

With this change, the domain of variable declarations can be specified.
Variables can have the integer domain, in which case additional integer-
specific simplification rules apply. Aside from that, the noninteger
domain represents precomputed values. An additional “unknown” domain is
introduced to flag variable domains prior to determining whether they
are integer or not.

include/anthem/AST.h

@@ -2,6 +2,7 @@
 #define __ANTHEM__AST_H
 
 #include <anthem/ASTForward.h>
+#include <anthem/Utils.h>
 
 namespace anthem
 {
@@ -369,6 +370,7 @@ struct VariableDeclaration
 	VariableDeclaration &operator=(VariableDeclaration &&other) = default;
 
 	Type type;
+	Domain domain{Domain::Unknown};
 	std::string name;
 };
 

include/anthem/Utils.h

@@ -33,6 +33,15 @@ enum class OperationResult
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
+enum class Domain
+{
+	Noninteger,
+	Integer,
+	Unknown,
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
 }
 
 #endif