Read curves vector from binary file

MathLib/Curve/CreatePiecewiseLinearCurve.cpp

@@ -12,21 +12,91 @@
 
 #include "CreatePiecewiseLinearCurve.h"
 
+#include <boost/endian/conversion.hpp>
+#include <fstream>
+#include <iostream>
+#include <vector>
+
 #include "BaseLib/ConfigTree.h"
 #include "BaseLib/Error.h"
+#include "BaseLib/FileTools.h"
+#include "BaseLib/StringTools.h"
 
 namespace MathLib
 {
 
+std::vector<double> readDoublesFromBinaryFile(const std::string& filename)
+{
+    auto prj_dir = BaseLib::getProjectDirectory();
+    std::string path_to_file = BaseLib::joinPaths(prj_dir, filename);
+
+    std::ifstream file(path_to_file, std::ios::binary);
+    if (!file)
+    {
+        OGS_FATAL("File {:s} at path {:s} for curve definition not found",
+                  filename, prj_dir);
+    }
+
+    // Determine file size
+    file.seekg(0, std::ios::end);
+    std::streamsize size = file.tellg();
+    file.seekg(0, std::ios::beg);
+
+    // Initialize vector with the right size
+    std::vector<double> result(size / sizeof(double));
+
+    // read data directly into the vector
+    if (!file.read(reinterpret_cast<char*>(result.data()), size))
+    {
+        OGS_FATAL("Could not read curve definition from file {:s}.", filename);
+    }
+
+    if constexpr (std::endian::native != std::endian::little)
+    {
+        // swap endians if needed
+        std::transform(
+            result.begin(), result.end(), result.begin(),
+            [](double value)
+            {
+                return std::bit_cast<double>(boost::endian::endian_reverse(
+                    std::bit_cast<uint64_t>(value)));
+            });
+    }
+
+    return result;
+}
+
 PiecewiseLinearCurveConfig parsePiecewiseLinearCurveConfig(
     BaseLib::ConfigTree const& config)
 {
-    auto x =
-        //! \ogs_file_param{curve__coords}
-        config.getConfigParameter<std::vector<double>>("coords");
-    auto y =
-        //! \ogs_file_param{curve__values}
-        config.getConfigParameter<std::vector<double>>("values");
+    const bool read_from_file =  //! \ogs_file_param{curve__read_from_file}
+        config.getConfigParameter<bool>("read_from_file", false);
+
+    std::vector<double> x;
+    std::vector<double> y;
+
+    if (read_from_file == true)
+    {
+        auto const coords_file_name =
+            //! \ogs_file_param{curve__coords}
+            config.getConfigParameter<std::string>("coords");
+        auto const values_file_name =
+            //! \ogs_file_param{curve__values}
+            config.getConfigParameter<std::string>("values");
+
+        x = readDoublesFromBinaryFile(coords_file_name);
+
+        y = readDoublesFromBinaryFile(values_file_name);
+    }
+    else
+    {
+        x =
+            //! \ogs_file_param{curve__coords}
+            config.getConfigParameter<std::vector<double>>("coords");
+        y =
+            //! \ogs_file_param{curve__values}
+            config.getConfigParameter<std::vector<double>>("values");
+    }
 
     if (x.empty() || y.empty())
     {

MathLib/Curve/CreatePiecewiseLinearCurve.h

@@ -28,6 +28,8 @@ struct PiecewiseLinearCurveConfig
     std::vector<double> ys;
 };
 
+std::vector<double> readDoublesFromBinaryFile(const std::string& filename);
+
 PiecewiseLinearCurveConfig parsePiecewiseLinearCurveConfig(
     BaseLib::ConfigTree const& config);