Add ForwardDemesGraph::number_of_demes() const. (#983)

molpopgen · Sep 2, 2022 · 09e53e3 · 09e53e3
1 parent 6c21cd1
commit 09e53e3
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Showing 3 changed files with 19 additions and 1 deletion.
diff --git a/cpptests/test_forward_demes_graph.cc b/cpptests/test_forward_demes_graph.cc
@@ -27,6 +27,7 @@ BOOST_FIXTURE_TEST_CASE(test_zero_length_single_deme_model, SingleDemeModel)
 BOOST_FIXTURE_TEST_CASE(single_deme_model_with_burn_in, SingleDemeModel)
 {
     fwdpy11_core::ForwardDemesGraph g(yaml, 10);
+    BOOST_REQUIRE_EQUAL(g.number_of_demes(), 1);
     fwdpy11::DiploidPopulation pop(100, 1.0);
     g.initialize_model(pop.generation);
     auto end_time = g.model_end_time();
@@ -43,6 +44,7 @@ BOOST_FIXTURE_TEST_CASE(single_deme_model_with_burn_in_THE_CODE_WE_WANT_TO_WRITE
                         SingleDemeModel)
 {
     fwdpy11_core::ForwardDemesGraph g(yaml, 10);
+    BOOST_REQUIRE_EQUAL(g.number_of_demes(), 1);
     fwdpy11::DiploidPopulation pop(100, 1.0);
     g.initialize_model(pop.generation);
     auto end_time = g.model_end_time();

diff --git a/lib/core/demes/forward_graph.hpp b/lib/core/demes/forward_graph.hpp
@@ -24,5 +24,6 @@ namespace fwdpy11_core
         bool iterating_model() const;
         void iterate_state();
         std::uint32_t model_end_time() const;
+        std::ptrdiff_t number_of_demes() const;
     };
 }
diff --git a/lib/demes/forward_graph.cc b/lib/demes/forward_graph.cc
@@ -1,3 +1,4 @@
+#include <cstddef>
 #include <cstdint>
 #include <cstdlib>
 #include <cassert>
@@ -14,13 +15,21 @@ namespace fwdpy11_core
     struct ForwardDemesGraph::forward_graph_implementation
     {
         graph_ptr_t graph;
+        std::ptrdiff_t number_of_demes;
 
         forward_graph_implementation(const std::string &yaml, std::uint32_t burnin)
-            : graph(demes_forward_graph_allocate(), &demes_forward_graph_deallocate)
+            : graph(demes_forward_graph_allocate(), &demes_forward_graph_deallocate),
+              number_of_demes{-1}
         {
             auto code = demes_forward_graph_initialize_from_yaml(
                 yaml.c_str(), static_cast<double>(burnin), graph.get());
             handle_error_code(code);
+            number_of_demes = demes_forward_graph_number_of_demes(graph.get());
+            if (number_of_demes < 1)
+                {
+                    throw fwdpy11::discrete_demography::DemographyError(
+                        "number of demes must be >= 1");
+                }
         }
 
         void handle_error_code(std::int32_t code) const;
@@ -135,4 +144,10 @@ namespace fwdpy11_core
                 pimpl->update_internal_state(*t);
             }
     };
+
+    std::ptrdiff_t
+    ForwardDemesGraph::number_of_demes() const
+    {
+        return pimpl->number_of_demes;
+    }
 }