typedef struct BooleanLogic BooleanLogic;
typedef struct BooleanPredicate BooleanPredicate;
+struct ASTNode;
+typedef struct ASTNode ASTNode;
+
struct Boolean;
typedef struct Boolean Boolean;
struct Order;
typedef struct Order Order;
+struct OrderPair;
+typedef struct OrderPair OrderPair;
+
struct ElementEncoding;
typedef struct ElementEncoding ElementEncoding;