From 0502cb0a7e707148886a7b4d21dbe557c508f9ce Mon Sep 17 00:00:00 2001
From: David Allemang <david.allemang@kitware.com>
Date: Thu, 24 Feb 2022 14:58:45 -0500
Subject: [PATCH] WIP: Copy combinations logic from demo

---
 CMakeLists.txt    |  5 ++++-
 include/combo.hpp | 30 ++++++++++++++++++++++++++++++
 src/combotest.cpp | 22 ++++++++++++++++++++++
 3 files changed, 56 insertions(+), 1 deletion(-)
 create mode 100644 include/combo.hpp
 create mode 100644 src/combotest.cpp

diff --git a/CMakeLists.txt b/CMakeLists.txt
index e6b2952..115aaba 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -35,4 +35,7 @@ add_executable(serial src/serialtest.cpp)
 target_link_libraries(serial eigen nlohmann_json)
 
 add_executable(tctest src/tctest.cpp)
-target_link_libraries(tctest PUBLIC eigen tc)
+target_link_libraries(tctest eigen tc)
+
+add_executable(combotest src/combotest.cpp)
+target_link_libraries(combotest eigen tc)
diff --git a/include/combo.hpp b/include/combo.hpp
new file mode 100644
index 0000000..3a5331f
--- /dev/null
+++ b/include/combo.hpp
@@ -0,0 +1,30 @@
+#pragma once
+
+#include <set>
+#include <algorithm>
+
+template<typename V, typename M>
+V select(const V &data, const M &mask, size_t count) {
+    V result;
+    result.reserve(count);
+
+    for (int i = 0; i < mask.size(); ++i) {
+        if (mask[i]) result.push_back(data[i]);
+    }
+
+    return result;
+}
+
+template<typename V>
+std::vector<V> combinations(const V &data, const size_t count) {
+    std::vector<V> result;
+
+    std::vector<bool> mask(data.size(), false);
+    std::fill(mask.begin(), mask.begin() + count, true);
+
+    do {
+        result.push_back(select(data, mask, count));
+    } while (std::next_permutation(mask.begin(), mask.end(), std::greater<>()));
+
+    return result;
+}
diff --git a/src/combotest.cpp b/src/combotest.cpp
new file mode 100644
index 0000000..60cb52d
--- /dev/null
+++ b/src/combotest.cpp
@@ -0,0 +1,22 @@
+#include <combo.hpp>
+
+#include <iostream>
+
+std::ostream &operator<<(std::ostream &o, const std::vector<int> &data) {
+    o << "[ ";
+    for (const auto &el: data) {
+        o << el << " ";
+    }
+    o << "]";
+    return o;
+}
+
+int main() {
+    std::vector<int> data{1, 2, 3, 4, 5};
+
+    for (const auto &combo: combinations(data, 3)) {
+        std::cout << combo << std::endl;
+    }
+
+    return EXIT_SUCCESS;
+}