From 619def44c1cca9f3cdf63544d5f24f2c7a7d9b77 Mon Sep 17 00:00:00 2001
From: Klaus Aehlig <klaus.aehlig@huawei.com>
Date: Tue, 22 Feb 2022 17:03:21 +0100
Subject: Initial self-hosting commit

This is the initial version of our tool that is able to
build itself. In can be bootstrapped by

  ./bin/bootstrap.py

Co-authored-by: Oliver Reiche <oliver.reiche@huawei.com>
Co-authored-by: Victor Moreno <victor.moreno1@huawei.com>
---
 src/buildtool/file_system/jsonfs.hpp | 47 ++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 src/buildtool/file_system/jsonfs.hpp

(limited to 'src/buildtool/file_system/jsonfs.hpp')

diff --git a/src/buildtool/file_system/jsonfs.hpp b/src/buildtool/file_system/jsonfs.hpp
new file mode 100644
index 00000000..0ec381c7
--- /dev/null
+++ b/src/buildtool/file_system/jsonfs.hpp
@@ -0,0 +1,47 @@
+#ifndef INCLUDED_SRC_BUILDTOOL_FILE_SYSTEM_JSONFS_HPP
+#define INCLUDED_SRC_BUILDTOOL_FILE_SYSTEM_JSONFS_HPP
+
+#include <exception>
+#include <filesystem>
+#include <fstream>
+#include <optional>
+
+#include "src/buildtool/file_system/file_system_manager.hpp"
+#include "src/buildtool/file_system/object_type.hpp"
+#include "src/utils/cpp/json.hpp"
+
+class Json {
+  public:
+    // Note that we are not using std::pair<std::nlohmann, bool> and being
+    // coherent with FileSystemManager::ReadFile because there is a bug in llvm
+    // toolchain related to type_traits that does not allow us to use
+    // std::pair<T,U> where T or U are nlohmann::json.
+    // LLVM bug report: https://bugs.llvm.org/show_bug.cgi?id=48507
+    // Minimal example: https://godbolt.org/z/zacedsGzo
+    [[nodiscard]] static auto ReadFile(
+        std::filesystem::path const& file) noexcept
+        -> std::optional<nlohmann::json> {
+        auto const type = FileSystemManager::Type(file);
+        if (not type or not IsFileObject(*type)) {
+            Logger::Log(LogLevel::Debug,
+                        "{} can not be read because it is not a file.",
+                        file.string());
+            return std::nullopt;
+        }
+        try {
+            nlohmann::json content;
+            std::ifstream file_reader(file.string());
+            if (file_reader.is_open()) {
+                file_reader >> content;
+                return content;
+            }
+            return std::nullopt;
+        } catch (std::exception const& e) {
+            Logger::Log(LogLevel::Error, e.what());
+            return std::nullopt;
+        }
+    }
+
+};  // Class Json
+
+#endif  // INCLUDED_SRC_BUILDTOOL_FILE_SYSTEM_JSONFS_HPP
-- 
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