read write cluster file (#60)

* Read and write cluster files (save work)

* add reading test

* use define for examples env variable and fix ci

* read and write cluster files (working)

* fix cluster CI

examples/cluster_example.cpp

@@ -0,0 +1,53 @@
+#include "aare/core/defs.hpp"
+#include "aare/file_io/ClusterFile.hpp"
+#include <cassert>
+#include <iostream>
+
+using namespace aare;
+int main() {
+    auto PROJECT_ROOT_DIR = std::filesystem::path(getenv("AARE_ROOT_DIR"));
+    std::filesystem::path const fpath(PROJECT_ROOT_DIR / "data" / "clusters" / "single_frame_97_clustrers.clust");
+
+    // reading a file
+    aare::ClusterFile cf(fpath, "r");
+    std::cout << "file opened " << '\n';
+    std::cout << "n_clusters " << cf.count() << '\n';
+    std::cout << "frame_number " << cf.frame() << '\n';
+    std::cout << "file size: " << cf.count() << '\n';
+    cf.seek(0); // seek to the beginning of the file (this is the default behavior of the constructor)
+
+    auto cluster = cf.read(97);
+
+    std::cout << "read 10 clusters" << '\n';
+    int offset = 0;
+    int data_offset = 0;
+    for (auto c : cluster) {
+        assert(c.y == offset + 200);
+        for (int i = 0; i < 9; i++) {
+            assert(c.data[i] == data_offset + i);
+        }
+
+        offset++;
+        data_offset += 9;
+    }
+
+    // writing a file
+    std::filesystem::path const fpath_out("/tmp/cluster_example_file.clust");
+    aare::ClusterFile cf_out(fpath_out, "w", ClusterFileConfig(1, 44));
+    std::cout << "file opened for writing" << '\n';
+    std::vector<Cluster> clusters;
+    for (int i = 0; i < 1084; i++) {
+        Cluster c;
+        c.x = i;
+        c.y = i + 200;
+        for (int j = 0; j < 9; j++) {
+            c.data[j] = j;
+        }
+        clusters.push_back(c);
+    }
+    cf_out.write(clusters);
+    std::cout << "wrote 10 clusters" << '\n';
+    cf_out.update_header();
+
+    return 0;
+}