[#xx] Add support for SELECT-FILTER expressions

Signed-off-by: Alejandro Lopez <a.lopez@yadro.com>

netmap/netmap.go

@@ -158,6 +158,57 @@ func (m NetMap) PlacementVectors(vectors [][]NodeInfo, pivot []byte) ([][]NodeIn
 	return result, nil
 }
 
+// SelectFilterNodes returns a two-dimensional list of nodes as a result of applying the
+// given SelectFilterExpr to the NetMap.
+// If the SelectFilterExpr contains only filters, the result contains a single row with the
+// result of the last filter application.
+// If the SelectFilterExpr contains only selectors, the result contains the selection rows
+// of the last select application.
+func (m NetMap) SelectFilterNodes(expr *SelectFilterExpr) ([][]NodeInfo, error) {
+	p := PlacementPolicy{
+		filters: expr.filters,
+	}
+
+	if expr.selector != nil {
+		p.selectors = append(p.selectors, *expr.selector)
+	}
+
+	c := newContext(m)
+	c.setCBF(expr.cbf)
+
+	if err := c.processFilters(p); err != nil {
+		return nil, err
+	}
+	if err := c.processSelectors(p); err != nil {
+		return nil, err
+	}
+
+	if expr.selector == nil {
+		var ret []NodeInfo
+		lastFilter := expr.filters[len(expr.filters)-1]
+		for _, ni := range m.nodes {
+			if c.match(c.processedFilters[lastFilter.GetName()], ni) {
+				ret = append(ret, ni)
+			}
+		}
+		return [][]NodeInfo{ret}, nil
+	}
+
+	sel, err := c.getSelection(*c.processedSelectors[expr.selector.GetName()])
+	if err != nil {
+		return nil, err
+	}
+
+	var ret [][]NodeInfo
+	for i, ns := range sel {
+		ret = append(ret, []NodeInfo{})
+		for _, n := range ns {
+			ret[i] = append(ret[i], n)
+		}
+	}
+	return ret, nil
+}
+
 // ContainerNodes returns two-dimensional list of nodes as a result of applying
 // given PlacementPolicy to the NetMap. Each line of the list corresponds to a
 // replica descriptor. Line order corresponds to order of ReplicaDescriptor list