added FileUtils

include/tgbotxx/utils/FileUtils.hpp

@@ -0,0 +1,77 @@
+#pragma once
+#include <filesystem>
+#include <fstream>
+#include <functional>
+#include <string>
+#include <tgbotxx/Exception.hpp>
+#include <vector>
+namespace fs = std::filesystem;
+
+namespace tgbotxx {
+  /// @brief Namespace contains useful File related utility functions.
+  namespace FileUtils {
+    /// @brief Read entire file into an std::string
+    /// @throws Exception on failure
+    static std::string read(const fs::path& filename) {
+      if (std::ifstream ifs{filename, std::ios::ate | std::ios::binary}) {
+        std::string buffer(ifs.tellg(), '\000');
+        ifs.seekg(0, std::ios::beg);
+        ifs.read(buffer.data(), buffer.size());
+        ifs.close();
+        return buffer;
+      } else {
+        throw Exception("No such file " + filename.string());
+      }
+    }
+
+    /// @brief Read entire file lines into std::vector<std::string>
+    /// @throws Exception on failure
+    static std::vector<std::string> readLines(const fs::path& filename) {
+      if (std::ifstream ifs{filename, std::ios::binary}) {
+        std::vector<std::string> lines{};
+        std::string line{};
+        while (std::getline(ifs, line)) {
+          lines.push_back(line);
+        }
+        ifs.close();
+        return lines;
+      } else {
+        throw Exception("No such file " + filename.string());
+      }
+    }
+
+    /// @brief Read file chunk by chunk
+    /// @throws Exception on failure
+    static void readChunks(const fs::path& filename, const std::size_t maxChunkSize, const std::function<void(std::vector<std::uint8_t>&&)>& callback) {
+      if (std::ifstream ifs{filename, std::ios::binary}) {
+        while (!ifs.eof()) {
+          std::vector<std::uint8_t> chunk(maxChunkSize, '\000');
+          ifs.read(reinterpret_cast<char *>(chunk.data()), chunk.size());
+
+          // resize chunk if we read bytes less than max_chunk_size
+          const auto bytes_read = ifs.gcount();
+          if (bytes_read < maxChunkSize)
+            chunk.resize(bytes_read);
+
+          // serve chunk
+          callback(std::move(chunk));
+        }
+        ifs.close();
+      } else {
+        throw Exception("No such file " + filename.string());
+      }
+    }
+
+    /// @brief Write buffer string to a new file
+    /// @throws Exception on failure
+    static void write(const fs::path& filename, const std::string& buffer) {
+      if (std::ofstream ofs{filename, std::ios::binary}) {
+        ofs.write(buffer.data(), buffer.size());
+        ofs.close();
+      } else {
+        throw Exception("Failed to write file " + filename.string());
+      }
+    }
+
+  }
+}