Add set discard superseded method to api (#1534)

Closes #1519

5 files changed, 96 insertions, 1 deletions

diff --git a/scripts/reference_exported_symbols.txt b/scripts/reference_exported_symbols.txt
index f3d13bd7..bdfdd475 100644
--- a/scripts/reference_exported_symbols.txt
+++ b/scripts/reference_exported_symbols.txt
@@ -948,6 +948,7 @@ proj_operation_factory_context_set_allow_use_intermediate_crs
 proj_operation_factory_context_set_area_of_interest
 proj_operation_factory_context_set_crs_extent_use
 proj_operation_factory_context_set_desired_accuracy
+proj_operation_factory_context_set_discard_superseded
 proj_operation_factory_context_set_grid_availability_use
 proj_operation_factory_context_set_spatial_criterion
 proj_operation_factory_context_set_use_proj_alternative_grid_names
diff --git a/src/iso19111/c_api.cpp b/src/iso19111/c_api.cpp
index 7a77ccfb..a125261a 100644
--- a/src/iso19111/c_api.cpp
+++ b/src/iso19111/c_api.cpp
@@ -6578,6 +6578,28 @@ void proj_operation_factory_context_set_allowed_intermediate_crs(
 
 // ---------------------------------------------------------------------------
 
+/** \brief Set whether transformations that are superseded (but not deprecated)
+ * should be discarded.
+ *
+ * @param ctx PROJ context, or NULL for default context
+ * @param factory_ctx Operation factory context. must not be NULL
+ * @param discard superseded crs or not
+ */
+void PROJ_DLL proj_operation_factory_context_set_discard_superseded(
+    PJ_CONTEXT *ctx, PJ_OPERATION_FACTORY_CONTEXT *factory_ctx,
+    int discard) {
+    SANITIZE_CTX(ctx);
+    assert(factory_ctx);
+    try {        
+        factory_ctx->operationContext->setDiscardSuperseded(discard != 0);
+    } catch (const std::exception &e) {
+        proj_log_error(ctx, __FUNCTION__, e.what());
+    }
+}
+
+
+// ---------------------------------------------------------------------------
+
 /** \brief Find a list of CoordinateOperation from source_crs to target_crs.
  *
  * The operations are sorted with the most relevant ones first: by
diff --git a/src/iso19111/coordinateoperation.cpp b/src/iso19111/coordinateoperation.cpp
index 7f3a2137..822f5822 100644
--- a/src/iso19111/coordinateoperation.cpp
+++ b/src/iso19111/coordinateoperation.cpp
@@ -10238,7 +10238,8 @@ struct FilterResults {
         // results
         // ...
         removeSyntheticNullTransforms();
-        removeUninterestingOps();
+        if (context->getDiscardSuperseded())
+          removeUninterestingOps();
         removeDuplicateOps();
         removeSyntheticNullTransforms();
         return *this;
diff --git a/src/proj.h b/src/proj.h
index 25cd981c..4328e7ef 100644
--- a/src/proj.h
+++ b/src/proj.h
@@ -941,6 +941,11 @@ void PROJ_DLL proj_operation_factory_context_set_allowed_intermediate_crs(
     PJ_OPERATION_FACTORY_CONTEXT *factory_ctx,
     const char* const *list_of_auth_name_codes);
 
+void PROJ_DLL proj_operation_factory_context_set_discard_superseded(
+    PJ_CONTEXT *ctx,
+    PJ_OPERATION_FACTORY_CONTEXT *factory_ctx,
+    int discard);
+
 /* ------------------------------------------------------------------------- */
 
 
diff --git a/test/unit/test_c_api.cpp b/test/unit/test_c_api.cpp
index bfbae1a5..e2d013b1 100644
--- a/test/unit/test_c_api.cpp
+++ b/test/unit/test_c_api.cpp
@@ -1352,6 +1352,72 @@ TEST_F(CApi, proj_create_operations) {
 
 // ---------------------------------------------------------------------------
 
+TEST_F(CApi, proj_create_operations_discard_superseded) {
+  auto ctxt = proj_create_operation_factory_context(m_ctxt, nullptr);
+  ASSERT_NE(ctxt, nullptr);
+  ContextKeeper keeper_ctxt(ctxt);
+
+  auto source_crs = proj_create_from_database(
+    m_ctxt, "EPSG", "4203", PJ_CATEGORY_CRS, false, nullptr); // AGD84
+  ASSERT_NE(source_crs, nullptr);
+  ObjectKeeper keeper_source_crs(source_crs);
+
+  auto target_crs = proj_create_from_database(
+    m_ctxt, "EPSG", "4326", PJ_CATEGORY_CRS, false, nullptr); // WGS84
+  ASSERT_NE(target_crs, nullptr);
+  ObjectKeeper keeper_target_crs(target_crs);
+
+  proj_operation_factory_context_set_spatial_criterion(
+    m_ctxt, ctxt, PROJ_SPATIAL_CRITERION_PARTIAL_INTERSECTION);
+
+  proj_operation_factory_context_set_grid_availability_use(
+    m_ctxt, ctxt, PROJ_GRID_AVAILABILITY_IGNORED);
+
+  proj_operation_factory_context_set_discard_superseded(
+    m_ctxt, ctxt, true);
+
+  auto res = proj_create_operations(m_ctxt, source_crs, target_crs, ctxt);
+  ASSERT_NE(res, nullptr);
+  ObjListKeeper keeper_res(res);
+
+  EXPECT_EQ(proj_list_get_count(res), 2);
+  }
+
+// ---------------------------------------------------------------------------
+
+TEST_F(CApi, proj_create_operations_dont_discard_superseded) {
+  auto ctxt = proj_create_operation_factory_context(m_ctxt, nullptr);
+  ASSERT_NE(ctxt, nullptr);
+  ContextKeeper keeper_ctxt(ctxt);
+
+  auto source_crs = proj_create_from_database(
+    m_ctxt, "EPSG", "4203", PJ_CATEGORY_CRS, false, nullptr); // AGD84
+  ASSERT_NE(source_crs, nullptr);
+  ObjectKeeper keeper_source_crs(source_crs);
+
+  auto target_crs = proj_create_from_database(
+    m_ctxt, "EPSG", "4326", PJ_CATEGORY_CRS, false, nullptr); // WGS84
+  ASSERT_NE(target_crs, nullptr);
+  ObjectKeeper keeper_target_crs(target_crs);
+
+  proj_operation_factory_context_set_spatial_criterion(
+    m_ctxt, ctxt, PROJ_SPATIAL_CRITERION_PARTIAL_INTERSECTION);
+
+  proj_operation_factory_context_set_grid_availability_use(
+    m_ctxt, ctxt, PROJ_GRID_AVAILABILITY_IGNORED);
+
+  proj_operation_factory_context_set_discard_superseded(
+    m_ctxt, ctxt, false);
+
+  auto res = proj_create_operations(m_ctxt, source_crs, target_crs, ctxt);
+  ASSERT_NE(res, nullptr);
+  ObjListKeeper keeper_res(res);
+
+  EXPECT_EQ(proj_list_get_count(res), 5);
+  }
+
+// ---------------------------------------------------------------------------
+
 TEST_F(CApi, proj_create_operations_with_pivot) {
 
     auto source_crs = proj_create_from_database(