Add support for aggregates in row views

Add a few aggregates implementations (min, max, distinct)
Use distinct to get the GB homepage in a single DB trip
Fix lessthan operation on variable types to be the right way round as it now matters

8 files changed, 173 insertions, 1 deletions

diff --git a/project2/common/aggregate.cpp b/project2/common/aggregate.cpp
new file mode 100644
index 0000000..1bb453b
--- /dev/null
+++ b/project2/common/aggregate.cpp
@@ -0,0 +1,24 @@
+#include "aggregate.h"
+
+Aggregate::Aggregate(ScriptNodePtr s) :
+	SourceObject(s),
+	value(s, "value")
+{
+}
+
+ValueAggregate::ValueAggregate(ScriptNodePtr s) :
+	Aggregate(s)
+{
+}
+
+SetAggregate::SetAggregate(ScriptNodePtr s) :
+	Aggregate(s)
+{
+}
+
+void
+Aggregate::pushValue() const
+{
+	pushValue(value());
+}
+
diff --git a/project2/common/aggregate.h b/project2/common/aggregate.h
new file mode 100644
index 0000000..18ad6a5
--- /dev/null
+++ b/project2/common/aggregate.h
@@ -0,0 +1,36 @@
+#ifndef AGGREGATE_H
+#define AGGREGATE_H
+
+#include "scripts.h"
+#include <boost/function.hpp>
+
+class Aggregate : public SourceObject {
+	public:
+		Aggregate(ScriptNodePtr);
+
+		virtual void reset() const = 0;
+		void pushValue() const;
+	protected:
+		virtual void pushValue(const VariableType &) const = 0;
+	private:
+		Variable value;
+};
+
+class ValueAggregate : public Aggregate {
+	public:
+		ValueAggregate(ScriptNodePtr);
+
+		virtual VariableType resultValue() const = 0;
+};
+typedef boost::intrusive_ptr<const ValueAggregate> ValueAggregateCPtr;
+
+class SetAggregate : public Aggregate {
+	public:
+		typedef boost::function1<void, VariableType> UseAgg;
+		SetAggregate(ScriptNodePtr);
+
+		virtual void onResultValues(const UseAgg &) const = 0;
+};
+typedef boost::intrusive_ptr<const SetAggregate> SetAggregateCPtr;
+
+#endif
diff --git a/project2/common/aggregates/distinct.cpp b/project2/common/aggregates/distinct.cpp
new file mode 100644
index 0000000..85e69c2
--- /dev/null
+++ b/project2/common/aggregates/distinct.cpp
@@ -0,0 +1,28 @@
+#include "../aggregate.h"
+#include <boost/foreach.hpp>
+
+class Distinct : public SetAggregate {
+	public:
+		Distinct(ScriptNodePtr s) :
+			SetAggregate(s)
+		{
+		}
+		void reset() const
+		{
+			result.clear();
+		}
+		void pushValue(const VariableType & v) const
+		{
+			result.insert(v);
+		}
+		void onResultValues(const SetAggregate::UseAgg & u) const
+		{
+			BOOST_FOREACH(const VariableType & v, result) {
+				u(v);
+			}
+		}
+	private:
+		mutable std::set<VariableType> result;
+};
+
+DECLARE_LOADER("distinct", Distinct);
diff --git a/project2/common/aggregates/max.cpp b/project2/common/aggregates/max.cpp
new file mode 100644
index 0000000..a6e528a
--- /dev/null
+++ b/project2/common/aggregates/max.cpp
@@ -0,0 +1,27 @@
+#include "../aggregate.h"
+
+class Max : public ValueAggregate {
+	public:
+		Max(ScriptNodePtr s) : ValueAggregate(s) { }
+
+		void reset() const
+		{
+			result = VariableType();
+		}
+		void pushValue(const VariableType & v) const
+		{
+			if (result < v) {
+				result = v;
+			}
+		}
+		VariableType resultValue() const
+		{
+			return result;
+		}
+	private:
+		mutable VariableType result;
+};
+
+DECLARE_LOADER("max", Max);
+
+
diff --git a/project2/common/aggregates/min.cpp b/project2/common/aggregates/min.cpp
new file mode 100644
index 0000000..14c63ae
--- /dev/null
+++ b/project2/common/aggregates/min.cpp
@@ -0,0 +1,32 @@
+#include "../aggregate.h"
+
+class Min : public ValueAggregate {
+	public:
+		Min(ScriptNodePtr s) :
+			ValueAggregate(s),
+			first(true)
+		{
+		}
+		void reset() const
+		{
+			result = VariableType();
+			first = true;
+		}
+		void pushValue(const VariableType & v) const
+		{
+			if (first || v < result) {
+				result = v;
+			}
+			first = false;
+		}
+		VariableType resultValue() const
+		{
+			return result;
+		}
+	private:
+		mutable VariableType result;
+		mutable bool first;
+};
+
+DECLARE_LOADER("min", Min);
+
diff --git a/project2/common/rowView.cpp b/project2/common/rowView.cpp
index 0f25a30..749651e 100644
--- a/project2/common/rowView.cpp
+++ b/project2/common/rowView.cpp
@@ -20,6 +20,8 @@ RowView::RowView(ScriptNodePtr p) :
 		viewColumns.insert(Columns::value_type(node->get_name(), Variable(node)));
 	}
 	p->script->loader.addLoadTarget(p, Storer::into<ElementLoader>(&subViews));
+	p->script->loader.addLoadTarget(p, Storer::into<ElementLoader>(&valueAggregates));
+	p->script->loader.addLoadTarget(p, Storer::into<ElementLoader>(&setAggregates));
 }
 
 RowView::~RowView()
@@ -46,6 +48,12 @@ RowView::rowReady(const RowState * rs) const
 	}
 	executeChildren();
 	presenter->finishRow();
+	BOOST_FOREACH(SetAggregateCPtr s, setAggregates) {
+		s->pushValue();
+	}
+	BOOST_FOREACH(ValueAggregateCPtr a, valueAggregates) {
+		a->pushValue();
+	}
 }
 
 void
@@ -53,8 +61,20 @@ RowView::execute(const MultiRowSetPresenter * p) const
 {
 	presenter = p;
 	presenter->addNewRowSet(rootName());
+
 	ScopeObject pres(boost::bind(&MultiRowSetPresenter::finishRowSet, p));
 	RowProcessor::execute();
+
+	BOOST_FOREACH(SetAggregateCPtr s, setAggregates) {
+		presenter->addNewRowSet(s->name);
+		ScopeObject pres(boost::bind(&MultiRowSetPresenter::finishRowSet, p));
+		s->onResultValues(boost::bind(&MultiRowSetPresenter::addNamedValue, p, "value", _1));
+		s->reset();
+	}
+	BOOST_FOREACH(ValueAggregateCPtr a, valueAggregates) {
+		presenter->addNamedValue(a->name, a->resultValue());
+		a->reset();
+	}
 }
 
 void
diff --git a/project2/common/rowView.h b/project2/common/rowView.h
index 4b90884..40ec8a9 100644
--- a/project2/common/rowView.h
+++ b/project2/common/rowView.h
@@ -4,6 +4,7 @@
 #include <boost/intrusive_ptr.hpp>
 #include "rowProcessor.h"
 #include "view.h"
+#include "aggregate.h"
 
 /// Project2 component to create output based on a records in a row set
 class RowView : public View, public RowProcessor {
@@ -25,6 +26,10 @@ class RowView : public View, public RowProcessor {
 		void executeChildren() const;
 		typedef ANONSTORAGEOF(View) SubViews;
 		SubViews subViews;
+		typedef ANONSTORAGEOF(ValueAggregate) ValueAggregates;
+		ValueAggregates valueAggregates;
+		typedef ANONSTORAGEOF(SetAggregate) SetAggregates;
+		SetAggregates setAggregates;
 		mutable const MultiRowSetPresenter * presenter;
 };
 
diff --git a/project2/common/variables.cpp b/project2/common/variables.cpp
index 8b4ce38..de0690b 100644
--- a/project2/common/variables.cpp
+++ b/project2/common/variables.cpp
@@ -165,7 +165,7 @@ class compi : public boost::static_visitor<bool> {
 		compi(const S & s) : _s(s) { }
 		bool operator()(const S & t) const
 		{
-			return _s < t;
+			return t < _s;
 		}
 		template <class T>
 		bool operator()(const T &) const