fix: validate the user inputs and add documentation for the CLI

.gitignore

@@ -25,4 +25,6 @@ cmake-build-*/
 $RECYCLE.BIN/
 .TemporaryItems
 ehthumbs.db
-Thumbs.db
+Thumbs.db
+
+.cache/

README.md

@@ -16,3 +16,28 @@ Features
 
 
 See the [test](test) folder for examples for building resources, using the valijson adapter, constexpr usage of resources, and firewalled usage of resources.
+
+## CLI Usage
+
+The json2cpp CLI can be used to convert a JSON file into a C++ source file that can be compiled into your project.
+
+```shell
+json2cpp version 0.0.1
+Usage: ./build/src/Debug/json2cpp [OPTIONS] [<document_name>] [<input_file_name>] [<output_base_name>]
+
+Positionals:
+  <document_name> TEXT        The name of the document used in the generated C++ namespace and include guards
+  <input_file_name> TEXT      The input JSON file to compile
+  <output_base_name> TEXT     The base path for the output files. It will generate <output_base_name>.cpp and <output_base_name>.hpp
+
+Options:
+  -h,--help                   Print this help message and exit
+  --version                   Show version information
+
+```
+
+For example, to compile a JSON file named `"./data/data.json"`:
+
+```shell
+json2cpp "data" "./data.json" "./data_source"
+```

src/json2cpp.cpp

@@ -24,6 +24,9 @@ SOFTWARE.
 
 
 #include "json2cpp.hpp"
+#include <algorithm>
+#include <cctype>
+#include <fmt/std.h>
 #include <fstream>
 
 std::string compile(const nlohmann::json &value, std::size_t &obj_count, std::vector<std::string> &lines)
@@ -85,8 +88,35 @@ std::string compile(const nlohmann::json &value, std::size_t &obj_count, std::ve
   return "unhandled";
 }
 
+
+/**
+ * @brief Checks if the given string is a valid C++ identifier. A valid C++ identifier is a string that starts with an
+ * alphabetic character and is followed by zero or more alphanumeric characters.
+ *
+ * @param name The string to check
+ * @return true if the string is a valid C++ identifier, false otherwise
+ */
+bool is_valid_identifier(const std::string_view name)
+{
+  // not empty
+  return !name.empty()
+         // starts with an alphabetic character
+         && std::isalpha(name.front()) != 0
+         // and is followed by zero or more alphanumeric characters
+         && std::all_of(name.begin(), name.end(), [](const auto &chr) { return std::isalnum(chr) != 0; });
+}
+
+void assert_valid_identifier(const std::string_view document_name)
+{
+  if (!is_valid_identifier(document_name)) {
+    throw std::invalid_argument(
+      fmt::format("document_name '{}' must be a non-empty valid C++ identifier", document_name));
+  }
+}
+
 compile_results compile(const std::string_view document_name, const nlohmann::json &json)
 {
+  assert_valid_identifier(document_name);
 
   std::size_t obj_count{ 0 };
 
@@ -150,6 +180,7 @@ compile_results compile(const std::string_view document_name, const std::filesys
   spdlog::info("Loading file: '{}'", filename.string());
 
   std::ifstream input(filename);
+  if (!input.is_open()) { throw std::runtime_error(fmt::format("Unable to open the input file name: {}", filename)); }
   nlohmann::json document;
   input >> document;
 
@@ -162,9 +193,12 @@ void write_compilation([[maybe_unused]] std::string_view document_name,
   const compile_results &results,
   const std::filesystem::path &base_output)
 {
+  assert_valid_identifier(document_name);
 
   const auto append_extension = [](std::filesystem::path name, std::string_view ext) { return name += ext; };
 
+  // Create the directory of the base_output's parent
+  std::filesystem::create_directories(base_output.parent_path());
 
   const auto hpp_name = append_extension(base_output, ".hpp");
   const auto cpp_name = append_extension(base_output, ".cpp");

src/main.cpp

@@ -23,9 +23,7 @@ SOFTWARE.
 */
 
 #include <filesystem>
-#include <fstream>
-#include <functional>
-#include <iostream>
+#include <string>
 
 #include "json2cpp.hpp"
 #include <CLI/CLI.hpp>
@@ -39,13 +37,18 @@ int main(int argc, const char **argv)
 
     std::string document_name;
     std::filesystem::path input_file_name;
-    std::filesystem::path output_base_name;
+    std::filesystem::path output_base_name = "out";
 
     bool show_version = false;
     app.add_flag("--version", show_version, "Show version information");
-    app.add_option("<document_name>", document_name);
-    app.add_option("<input_file_name>", input_file_name);
-    app.add_option("<output_base_name>", output_base_name);
+    app.add_option("<document_name>",
+      document_name,
+      "The name of the document used in the generated C++ namespace and include guards");
+    app.add_option("<input_file_name>", input_file_name, "The input JSON file to compile");
+    app.add_option("<output_base_name>",
+      output_base_name,
+      "The base path for the output filesThe base path for the output files. It will generate <output_base_name>.cpp "
+      "and <output_base_name>.hpp");
     CLI11_PARSE(app, argc, argv);
 
     compile_to(document_name, input_file_name, output_base_name);