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Add user callback to vf2_subgraph_mono to potentially stop search before each check. #280

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Add user callback to vf2_subgraph_mono to potentially stop search before each check. #280

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b937965
Add user callback to potentially stop search before each check.
cqc-alec Dec 14, 2021
3185125
Merge branch 'develop' into feature/vf2-callback
cqc-alec Feb 4, 2022
95a1d6a
Merge branch 'develop' into feature/vf2-callback
cqc-alec Feb 20, 2022
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25 changes: 20 additions & 5 deletions doc/vf2_sub_graph_iso.html
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Original file line number Diff line number Diff line change
Expand Up @@ -44,7 +44,8 @@ <h1>
typename SubGraphIsoMapCallback&gt;
bool vf2_subgraph_iso(const GraphSmall&amp; graph_small,
const GraphLarge&amp; graph_large,
SubGraphIsoMapCallback user_callback)
SubGraphIsoMapCallback user_callback,
bool(*user_step_callback)() = &vf2_trivial_step_callback)
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Instead of being a concrete function pointer, this should be a template like most other parameters. That way, users can pass in whatever they like: lambda, function object, etc.



<em class="comment">// Named parameter version</em>
Expand All @@ -59,7 +60,8 @@ <h1>
const GraphLarge&amp; graph_large,
SubGraphIsoMapCallback user_callback,
const VertexOrderSmall&amp; vertex_order_small,
const bgl_named_params&lt;Param, Tag, Rest&gt;&amp; params)
const bgl_named_params&lt;Param, Tag, Rest&gt;&amp; params,
bool(*user_step_callback)() = &vf2_trivial_step_callback)


<em class="comment">// Non-named parameter version</em>
Expand All @@ -78,7 +80,8 @@ <h1>
IndexMapLarge index_map_large,
const VertexOrderSmall&amp; vertex_order_small,
EdgeEquivalencePredicate edge_comp,
VertexEquivalencePredicate vertex_comp)
VertexEquivalencePredicate vertex_comp,
bool(*user_step_callback)() = &vf2_trivial_step_callback)
</pre>
<p>
An isomorphism between two graphs <em>G<sub>1</sub>=(V<sub>1</sub>, E<sub>1</sub>)</em>
Expand All @@ -95,9 +98,9 @@ <h1>
<p>
This function finds all induced subgraph isomorphisms between
graphs <tt>graph_small</tt> and <tt>graph_large</tt> and outputs them to
<tt>user_callback</tt>. It continues until <tt>user_callback</tt>
<tt>user_callback</tt>. It continues until <tt>user_callback</tt> or <tt>user_step_callback</tt>
returns false or the search space has been fully explored. <tt>vf2_subgraph_iso</tt>
returns true if a graph-subgraph isomorphism exists and false otherwise.
returns true if a graph-subgraph isomorphism was found and false otherwise.
<tt>EdgeEquivalencePredicate</tt> and
<tt>VertexEquivalencePredicate</tt> predicates are used to test whether
edges and vertices are equivalent. To use property maps for equivalence,
Expand Down Expand Up @@ -202,6 +205,18 @@ <h3>Parameters</h3>
</p>
</blockquote>

<p>OUT: <tt>bool(*user_step_callback)() = &vf2_trivial_step_callback</tt></p>
<blockquote>
<p>
A function to be called at each step of the search. If it returns false,
the search is terminated. The default always returns true. Unlike
<tt>user_callback</tt> (which is only called when a match is found),
this callback is called with high frequency; it may be used, for
example, to stop the search when a time limit is exceeded or for other
external reasons.
</p>
</blockquote>

<p>IN: <tt>const VertexOrderSmall&amp; vertex_order_small</tt></p>
<blockquote>
<p>
Expand Down
47 changes: 32 additions & 15 deletions include/boost/graph/vf2_sub_graph_iso.hpp
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Expand Up @@ -73,6 +73,11 @@ template < typename Graph1, typename Graph2 > struct vf2_print_callback
const Graph2& graph2_;
};

static bool vf2_trivial_step_callback()
{
return true;
}

namespace detail
{

Expand Down Expand Up @@ -748,8 +753,8 @@ namespace detail
// and tested for feasibility to extend the mapping. If a complete
// mapping is found, the mapping is output to user_callback in the form
// of a correspondence map (graph1 to graph2). Returning false from the
// user_callback will terminate the search. Function match will return
// true if the entire search space was explored.
// user_callback or user_step_callback will terminate the search. Function
// match will return true if a match was found.
template < typename Graph1, typename Graph2, typename IndexMap1,
typename IndexMap2, typename VertexOrder1,
typename EdgeEquivalencePredicate, typename VertexEquivalencePredicate,
Expand All @@ -758,7 +763,8 @@ namespace detail
SubGraphIsoMapCallback user_callback, const VertexOrder1& vertex_order1,
state< Graph1, Graph2, IndexMap1, IndexMap2, EdgeEquivalencePredicate,
VertexEquivalencePredicate, SubGraphIsoMapCallback,
problem_selection >& s)
problem_selection >& s,
bool(*user_step_callback)() = &vf2_trivial_step_callback)
{

typename VertexOrder1::const_iterator graph1_verts_iter;
Expand All @@ -773,6 +779,10 @@ namespace detail
bool found_match = false;

recur:
if (!user_step_callback()) {
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I think this callback should take in whatever data might change between each call to it. Even though in your case you'll ignore it, someone else might have a reason to examine the internals of whatever state is changing. I guess it's just that s object?

return found_match;
}

if (s.success())
{
if (!s.call_back(user_callback))
Expand Down Expand Up @@ -913,8 +923,9 @@ namespace detail
}

// Enumerates all graph sub-graph mono-/iso-morphism mappings between graphs
// graph_small and graph_large. Continues until user_callback returns true
// or the search space has been fully explored.
// graph_small and graph_large. Continues until user_callback or
// user_step_callback returns false or the search space has been fully
// explored.
template < problem_selector problem_selection, typename GraphSmall,
typename GraphLarge, typename IndexMapSmall, typename IndexMapLarge,
typename VertexOrderSmall, typename EdgeEquivalencePredicate,
Expand All @@ -924,7 +935,8 @@ namespace detail
IndexMapSmall index_map_small, IndexMapLarge index_map_large,
const VertexOrderSmall& vertex_order_small,
EdgeEquivalencePredicate edge_comp,
VertexEquivalencePredicate vertex_comp)
VertexEquivalencePredicate vertex_comp,
bool(*user_step_callback)() = &vf2_trivial_step_callback)
{

// Graph requirements
Expand Down Expand Up @@ -1007,7 +1019,8 @@ namespace detail
edge_comp, vertex_comp);

return detail::match(
graph_small, graph_large, user_callback, vertex_order_small, s);
graph_small, graph_large, user_callback, vertex_order_small, s,
user_step_callback);
}

} // namespace detail
Expand All @@ -1028,8 +1041,8 @@ vertex_order_by_mult(const Graph& graph)
}

// Enumerates all graph sub-graph monomorphism mappings between graphs
// graph_small and graph_large. Continues until user_callback returns true or
// the search space has been fully explored.
// graph_small and graph_large. Continues until user_callback or
// user_step_callback returns false or the search space has been fully explored.
template < typename GraphSmall, typename GraphLarge, typename IndexMapSmall,
typename IndexMapLarge, typename VertexOrderSmall,
typename EdgeEquivalencePredicate, typename VertexEquivalencePredicate,
Expand All @@ -1038,23 +1051,25 @@ bool vf2_subgraph_mono(const GraphSmall& graph_small,
const GraphLarge& graph_large, SubGraphIsoMapCallback user_callback,
IndexMapSmall index_map_small, IndexMapLarge index_map_large,
const VertexOrderSmall& vertex_order_small,
EdgeEquivalencePredicate edge_comp, VertexEquivalencePredicate vertex_comp)
EdgeEquivalencePredicate edge_comp, VertexEquivalencePredicate vertex_comp,
bool(*user_step_callback)() = &vf2_trivial_step_callback)
{
return detail::vf2_subgraph_morphism< detail::subgraph_mono >(graph_small,
graph_large, user_callback, index_map_small, index_map_large,
vertex_order_small, edge_comp, vertex_comp);
vertex_order_small, edge_comp, vertex_comp, user_step_callback);
}

// All default interface for vf2_subgraph_iso
template < typename GraphSmall, typename GraphLarge,
typename SubGraphIsoMapCallback >
bool vf2_subgraph_mono(const GraphSmall& graph_small,
const GraphLarge& graph_large, SubGraphIsoMapCallback user_callback)
const GraphLarge& graph_large, SubGraphIsoMapCallback user_callback,
bool(*user_step_callback)() = &vf2_trivial_step_callback)
{
return vf2_subgraph_mono(graph_small, graph_large, user_callback,
get(vertex_index, graph_small), get(vertex_index, graph_large),
vertex_order_by_mult(graph_small), always_equivalent(),
always_equivalent());
always_equivalent(), user_step_callback);
}

// Named parameter interface of vf2_subgraph_iso
Expand All @@ -1064,7 +1079,8 @@ template < typename GraphSmall, typename GraphLarge, typename VertexOrderSmall,
bool vf2_subgraph_mono(const GraphSmall& graph_small,
const GraphLarge& graph_large, SubGraphIsoMapCallback user_callback,
const VertexOrderSmall& vertex_order_small,
const bgl_named_params< Param, Tag, Rest >& params)
const bgl_named_params< Param, Tag, Rest >& params,
bool(*user_step_callback)() = &vf2_trivial_step_callback)
{
return vf2_subgraph_mono(graph_small, graph_large, user_callback,
choose_const_pmap(
Expand All @@ -1075,7 +1091,8 @@ bool vf2_subgraph_mono(const GraphSmall& graph_small,
choose_param(
get_param(params, edges_equivalent_t()), always_equivalent()),
choose_param(
get_param(params, vertices_equivalent_t()), always_equivalent()));
get_param(params, vertices_equivalent_t()), always_equivalent()),
user_step_callback);
}

// Enumerates all graph sub-graph isomorphism mappings between graphs
Expand Down
40 changes: 40 additions & 0 deletions test/vf2_sub_graph_iso_test_2.cpp
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Expand Up @@ -39,6 +39,18 @@ struct false_predicate
}
};

bool step_callback_always_false()
{
return false;
}

bool step_callback_max_10_steps()
{
static int n = 0;
n++;
return (n <= 10);
}

void test_empty_graph_cases()
{
typedef boost::adjacency_list< boost::vecS, boost::vecS,
Expand Down Expand Up @@ -201,9 +213,37 @@ BOOST_TEST(!got_hit);
}
}

void test_step_callback()
{
typedef boost::adjacency_list< boost::vecS, boost::vecS,
boost::bidirectionalS >
Graph;
Graph gEmpty, gLarge;
add_vertex(gLarge);

{ // isomorphism exists but search aborted
bool got_hit = false;
test_callback callback(got_hit, true);
bool found = vf2_subgraph_mono(gEmpty, gEmpty, callback,
&step_callback_always_false);
BOOST_TEST(!found);
BOOST_TEST(!got_hit);
}

{ // isomorphism exists and found within 10 steps
bool got_hit = false;
test_callback callback(got_hit, true);
bool found = vf2_subgraph_mono(gEmpty, gEmpty, callback,
&step_callback_max_10_steps);
BOOST_TEST(found);
BOOST_TEST(got_hit);
}
}

int main(int argc, char* argv[])
{
test_empty_graph_cases();
test_return_value();
test_step_callback();
return boost::report_errors();
}