Subgraph Labels (#285)

* subgraph labels

* adding more documentation for Label

* minor fixes

src/ngraph/pattern/matcher.cpp

@@ -46,9 +46,9 @@ namespace ngraph
             {
                 if (pattern_map[label] != graph_node)
                 {
-                    NGRAPH_DEBUG << "get_bound_node " << pattern_map[label]->get_name() << " , "
-                                 << pattern_map[label] << " NOT match " << graph_node->get_name()
-                                 << " , " << graph_node;
+                    NGRAPH_DEBUG << "[MATCHER] get_bound_node " << pattern_map[label]->get_name()
+                                 << " , " << pattern_map[label] << " NOT match "
+                                 << graph_node->get_name() << " , " << graph_node;
                     is_match = false;
                 }
             }
@@ -60,11 +60,23 @@ namespace ngraph
 
             if (is_match) //in case label was already bound this rebinds it to the same node (harmless; and the logic seems cleaner)
             {
-                NGRAPH_DEBUG << "(Re)binding get_bound_node " << graph_node->get_name() << " , "
-                             << graph_node << " , " << graph_node->get_name();
-                pattern_map[label] = graph_node;
-            }
+                auto args = get_arguments(label);
+                if (args.size() > 0)
+                {
+                    assert(args.size() ==
+                           1); //it should be impossible to construct labels w/ more than one arg
+                    NGRAPH_DEBUG << "[MATCHER] Label describes a sub graph in the pattern";
+                    is_match = match_node(args.at(0), graph_node, pattern_map);
+                }
 
+                if (is_match)
+                {
+                    NGRAPH_DEBUG << "[MATCHER] (Re)binding get_bound_node "
+                                 << graph_node->get_name() << " , " << graph_node << " , "
+                                 << graph_node->get_name();
+                    pattern_map[label] = graph_node;
+                }
+            }
             return is_match;
         }
 
@@ -91,6 +103,11 @@ namespace ngraph
                                  PatternMap& pattern_map)
         {
             assert(pattern_node && graph_node);
+
+            NGRAPH_DEBUG << pad(2 * m_depth) << "[MATCHER] in match_node : "
+                         << "pattern = " << pattern_node << " , " << pattern_node->get_name() << " "
+                         << "matched " << graph_node << " , " << graph_node->get_name();
+
             if (auto label_node = std::dynamic_pointer_cast<op::Label>(pattern_node))
             {
                 return match_pattern(label_node, graph_node, pattern_map);

src/ngraph/pattern/op/label.hpp

@@ -30,17 +30,43 @@ namespace ngraph
             class Label : public Pattern
             {
             public:
+                /// \brief creates a Label node from \sa node.
+                ///
+                /// this Label node can be bound to arbitrary nodes in an input graph
+                /// as long as provided \sa pred is satisfied and the node hasn't been previously bound to
+                /// a different node in the input graph
+                /// \code{.cpp}
+                /// auto pattern = pattern::op::Label::make_from_node(a); //a is op::Parameter
+                /// matcher.match(pattern, a));
+                /// \endcode
                 static std::shared_ptr<Label>
                     make_from_node(const std::shared_ptr<ngraph::Node>& node,
                                    Predicate pred = nullptr)
                 {
-                    auto label = std::make_shared<Label>(pred);
+                    auto label = std::make_shared<Label>(Nodes{}, pred);
                     label->set_value_type_checked(node->get_value_type());
                     return label;
                 }
 
-                Label(Predicate pred = nullptr)
-                    : Pattern("Label", Nodes{}, pred)
+                /// \brief creates a Label node containing a sub-pattern described by \sa node.
+                ///
+                /// this Label node can be bound only to the nodes in the input graph
+                /// that match the pattern specified by \sa node
+                /// Example:
+                /// \code{.cpp}
+                /// auto add = a + b; //a and b are op::Parameter in this example
+                /// auto label = pattern::op::Label::wrap(add);
+                /// \endcode
+                static std::shared_ptr<Label> wrap(const std::shared_ptr<ngraph::Node>& node,
+                                                   Predicate pred = nullptr)
+                {
+                    auto label = std::make_shared<Label>(Nodes{node}, pred);
+                    label->set_value_type_checked(node->get_value_type());
+                    return label;
+                }
+
+                Label(const Nodes& subgraph, Predicate pred)
+                    : Pattern("Label", Nodes{subgraph}, pred)
                 {
                 }
             };

test/pattern.cpp

@@ -346,4 +346,30 @@ TEST(pattern, matcher)
         make_shared<op::Constant>(element::Float32::element_type(), Shape{1}, std::to_string(1));
     auto patternf = pattern::op::Label::make_from_node(fconst1_0);
     ASSERT_FALSE(n.match(patternf * fconst1_0, a * iconst1_1)); //different iconst
+
+    //Subgraph labels
+    auto add = a + b;
+    auto label = pattern::op::Label::wrap(add);
+    ASSERT_TRUE(n.match(label, add));
+    ASSERT_EQ(n.get_pattern_map()[label], add);
+
+    ASSERT_FALSE(n.match(label, a - b));
+
+    ASSERT_TRUE(n.match(make_shared<op::Abs>(label), make_shared<op::Abs>(add)));
+    ASSERT_EQ(n.get_pattern_map()[label], add);
+
+    //Correlations
+    auto label1 = pattern::op::Label::make_from_node(a);
+    auto label2 = pattern::op::Label::wrap(label1 + b);
+    auto sub_label1 = label1 - label2;
+    ASSERT_TRUE(n.match(sub_label1, a - add));
+    ASSERT_EQ(n.get_pattern_map()[label1], a);
+    ASSERT_EQ(n.get_pattern_map()[label2], add);
+
+    ASSERT_FALSE(n.match(sub_label1, add - a));
+
+    auto add_label1 = label1 + label2;
+    ASSERT_TRUE(n.match(add_label1, add + a));
+    ASSERT_EQ(n.get_pattern_map()[label1], a);
+    ASSERT_EQ(n.get_pattern_map()[label2], add);
 }