Added filter compacting

Before statement compilation, empty filters are removed from group
filters, and childless group filters become empty filters.

3 files changed, 76 insertions, 42 deletions

@@ -871,7 +871,7 @@ namespace verbly {
       throw std::domain_error("This filter has no children");
     }
   }
-  
+
   filter filter::operator!() const
   {
     switch (type_)
@@ -1371,4 +1371,36 @@ namespace verbly {
     }
   }
 
+  filter filter::compact() const
+  {
+    switch (type_)
+    {
+      case type::empty:
+      case type::singleton:
+      {
+        return *this;
+      }
+
+      case type::group:
+      {
+        filter result(group_.orlogic);
+        for (const filter& child : group_.children)
+        {
+          filter compactedChild = child.compact();
+          if (compactedChild.type_ != type::empty)
+          {
+            result += child;
+          }
+        }
+
+        if (group_.children.empty())
+        {
+          result = {};
+        }
+
+        return result;
+      }
+    }
+  }
+
 };
@@ -8,7 +8,7 @@
 #include "enums.h"
 
 namespace verbly {
-  
+
   class filter {
   public:
     enum class type {
@@ -16,7 +16,7 @@ namespace verbly {
       singleton,
       group
     };
-    
+
     enum class comparison {
       int_equals,
       int_does_not_equal,
@@ -36,87 +36,89 @@ namespace verbly {
       hierarchally_matches,
       does_not_hierarchally_match
     };
-    
+
     // Copy and move constructors
-    
+
     filter(const filter& other);
     filter(filter&& other);
-    
+
     // Assignment
-    
+
     filter& operator=(filter other);
-    
+
     // Swap
-    
+
     friend void swap(filter& first, filter& second);
-    
+
     // Destructor
-    
+
     ~filter();
-    
+
     // Accessors
-    
+
     type getType() const
     {
       return type_;
     }
-    
+
     // Empty
-    
+
     filter();
-    
+
     // Singleton
-    
+
     filter(field filterField, comparison filterType, int filterValue);
     filter(field filterField, comparison filterType, std::string filterValue);
     filter(field filterField, comparison filterType, bool filterValue);
     filter(field filterField, comparison filterType);
     filter(field joinOn, comparison filterType, filter joinCondition);
-    
+
     field getField() const;
-    
+
     comparison getComparison() const;
-    
+
     filter getJoinCondition() const;
-    
+
     std::string getStringArgument() const;
-    
+
     int getIntegerArgument() const;
-    
+
     bool getBooleanArgument() const;
-    
+
     // Group
-    
+
     explicit filter(bool orlogic);
-    
+
     bool getOrlogic() const;
-    
+
     filter operator+(filter condition) const;
-    
+
     filter& operator+=(filter condition);
-    
+
     using const_iterator = std::list<filter>::const_iterator;
-    
+
     const_iterator begin() const;
-    
+
     const_iterator end() const;
-    
+
     // Negation
-    
+
     filter operator!() const;
-    
+
     // Groupifying
-    
+
     filter operator&&(filter condition) const;
     filter operator||(filter condition) const;
-    
+
     filter& operator&=(filter condition);
     filter& operator|=(filter condition);
-    
+
     // Utility
-    
+
     filter normalize(object context) const;
-    
+
+    filter compact() const;
+
   private:
     union {
       struct {
@@ -135,9 +137,9 @@ namespace verbly {
       } group_;
     };
     type type_ = type::empty;
-    
+
   };
-  
+
 };
 
 #endif /* end of include guard: FILTER_H_932BA9C6 */
@@ -16,7 +16,7 @@ namespace verbly {
   statement::statement(
     object context,
     filter queryFilter) :
-      statement(getTableForContext(context), queryFilter.normalize(context))
+      statement(getTableForContext(context), queryFilter.compact().normalize(context))
   {
   }