C API: add proj_concatoperation_get_step_count() and proj_concatoperation_get_step()

2 files changed, 66 insertions, 0 deletions

diff --git a/src/iso19111/c_api.cpp b/src/iso19111/c_api.cpp
index bc1d0bd8..7a77ccfb 100644
--- a/src/iso19111/c_api.cpp
+++ b/src/iso19111/c_api.cpp
@@ -6976,3 +6976,62 @@ PJ *proj_normalize_for_visualization(PJ_CONTEXT *ctx, const PJ *obj) {
         return nullptr;
     }
 }
+
+// ---------------------------------------------------------------------------
+
+/** \brief Returns the number of steps of a concatenated operation.
+ *
+ * The input object must be a concatenated operation.
+ *
+ * @param ctx PROJ context, or NULL for default context
+ * @param concatoperation Concatenated operation (must not be NULL)
+ * @return the number of steps, or 0 in case of error.
+ */
+int proj_concatoperation_get_step_count(PJ_CONTEXT *ctx,
+                                        const PJ *concatoperation) {
+    SANITIZE_CTX(ctx);
+    assert(concatoperation);
+    auto l_co = dynamic_cast<const ConcatenatedOperation *>(
+        concatoperation->iso_obj.get());
+    if (!l_co) {
+        proj_log_error(ctx, __FUNCTION__,
+                       "Object is not a ConcatenatedOperation");
+        return false;
+    }
+    return static_cast<int>(l_co->operations().size());
+}
+// ---------------------------------------------------------------------------
+
+/** \brief Returns a step of a concatenated operation.
+ *
+ * The input object must be a concatenated operation.
+ *
+ * The returned object must be unreferenced with proj_destroy() after
+ * use.
+ * It should be used by at most one thread at a time.
+ *
+ * @param ctx PROJ context, or NULL for default context
+ * @param concatoperation Concatenated operation (must not be NULL)
+ * @param i_step Index of the step to extract. Between 0 and
+ *               proj_concatoperation_get_step_count()-1
+ * @return Object that must be unreferenced with proj_destroy(), or NULL
+ * in case of error.
+ */
+PJ *proj_concatoperation_get_step(PJ_CONTEXT *ctx, const PJ *concatoperation,
+                                  int i_step) {
+    SANITIZE_CTX(ctx);
+    assert(concatoperation);
+    auto l_co = dynamic_cast<const ConcatenatedOperation *>(
+        concatoperation->iso_obj.get());
+    if (!l_co) {
+        proj_log_error(ctx, __FUNCTION__,
+                       "Object is not a ConcatenatedOperation");
+        return nullptr;
+    }
+    const auto &steps = l_co->operations();
+    if (i_step < 0 || static_cast<size_t>(i_step) >= steps.size()) {
+        proj_log_error(ctx, __FUNCTION__, "Invalid step index");
+        return nullptr;
+    }
+    return pj_obj_create(ctx, steps[i_step]);
+}
diff --git a/src/proj.h b/src/proj.h
index 0282ddfe..25cd981c 100644
--- a/src/proj.h
+++ b/src/proj.h
@@ -1064,6 +1064,13 @@ int PROJ_DLL proj_coordoperation_get_towgs84_values(PJ_CONTEXT *ctx,
                                                     int value_count,
                                                     int emit_error_if_incompatible);
 
+int PROJ_DLL proj_concatoperation_get_step_count(PJ_CONTEXT *ctx,
+                                                 const PJ *concatoperation);
+
+PJ PROJ_DLL *proj_concatoperation_get_step(PJ_CONTEXT *ctx,
+                                           const PJ *concatoperation,
+                                           int i_step);
+
 /**@}*/
 
 #ifdef __cplusplus