[Refactor] Refactor logging system (#181)

This PR refactors and simplifies the logging system by providing a tracing function and deletes the internal error class.

CMakeLists.txt

@@ -41,6 +41,7 @@ message(STATUS "Build type: ${CMAKE_BUILD_TYPE}")
 message(STATUS "Build Python bindings: ${XGRAMMAR_BUILD_PYTHON_BINDINGS}")
 message(STATUS "Build C++ tests: ${XGRAMMAR_BUILD_CXX_TESTS}")
 message(STATUS "CUDA architectures: ${XGRAMMAR_CUDA_ARCHITECTURES}")
+message(STATUS "Enable C++ trace: ${XGRAMMAR_ENABLE_CPPTRACE}")
 
 if(MSVC)
   set(CMAKE_CXX_FLAGS "/Wall ${CMAKE_CXX_FLAGS}")
@@ -69,6 +70,9 @@ target_include_directories(xgrammar PUBLIC ${XGRAMMAR_INCLUDE_PATH})
 if(XGRAMMAR_ENABLE_CPPTRACE)
   add_subdirectory(${PROJECT_SOURCE_DIR}/3rdparty/cpptrace)
   target_link_libraries(xgrammar PUBLIC cpptrace::cpptrace)
+  target_compile_definitions(xgrammar PUBLIC XGRAMMAR_ENABLE_CPPTRACE=1)
+else()
+  target_compile_definitions(xgrammar PUBLIC XGRAMMAR_ENABLE_CPPTRACE=0)
 endif()
 
 if(XGRAMMAR_BUILD_PYTHON_BINDINGS)

cpp/pybind/CMakeLists.txt

@@ -23,6 +23,9 @@ target_include_directories(xgrammar_bindings PUBLIC ${XGRAMMAR_INCLUDE_PATH})
 
 if(XGRAMMAR_ENABLE_CPPTRACE)
   target_link_libraries(xgrammar_bindings PUBLIC cpptrace::cpptrace)
+  target_compile_definitions(xgrammar_bindings PUBLIC XGRAMMAR_ENABLE_CPPTRACE=1)
+else()
+  target_compile_definitions(xgrammar_bindings PUBLIC XGRAMMAR_ENABLE_CPPTRACE=0)
 endif()
 
 set(LIB_OUTPUT_DIRECTORY "${PROJECT_SOURCE_DIR}/python/xgrammar")

cpp/support/cpptrace.h

@@ -8,11 +8,31 @@
 #ifndef XGRAMMAR_SUPPORT_CPPTRACE_H_
 #define XGRAMMAR_SUPPORT_CPPTRACE_H_
 
+#if XGRAMMAR_ENABLE_CPPTRACE == 1
 #include <cpptrace/cpptrace.hpp>
+#endif
+
+#include <string>
 
 namespace xgrammar {
 
+#if XGRAMMAR_ENABLE_CPPTRACE == 1
+
+// Flag to check if cpptrace feature is enabled
+static constexpr bool CPPTRACE_ENABLED = true;
+
 inline void PrintTrace() { cpptrace::generate_trace().print(); }
+inline std::string GetTraceString() { return cpptrace::generate_trace().to_string(true); }
+
+#else
+
+static constexpr bool CPPTRACE_ENABLED = false;
+
+// Provide empty implementation when cpptrace is disabled
+inline void PrintTrace() {}
+inline std::string GetTraceString() { return ""; }
+
+#endif
 
 }  // namespace xgrammar
 

cpp/support/logging.cc

@@ -3,20 +3,22 @@
  * \file xgrammar/support/logging.cc
  */
 #include "logging.h"
-#if (XGRAMMAR_LOG_CUSTOMIZE == 0)
+
 namespace xgrammar {
 
+#if XGRAMMAR_LOG_CUSTOMIZE == 0
+
 LogFatal::Entry& LogFatal::GetEntry() {
   static thread_local LogFatal::Entry result;
   return result;
 }
 
 const char* LogMessage::level_strings_[] = {
-    ": Debug: ",    // XGRAMMAR_LOG_LEVEL_DEBUG
     ": ",           // XGRAMMAR_LOG_LEVEL_INFO
+    ": Debug: ",    // XGRAMMAR_LOG_LEVEL_DEBUG
     ": Warning: ",  // XGRAMMAR_LOG_LEVEL_WARNING
-    ": Error: ",    // XGRAMMAR_LOG_LEVEL_ERROR
 };
 
-}  // namespace xgrammar
 #endif  // XGRAMMAR_LOG_CUSTOMIZE
+
+}  // namespace xgrammar

cpp/support/logging.h

@@ -23,45 +23,27 @@
 
 namespace xgrammar {
 
-/*!
- * \brief exception class that will be thrown by
- *  default logger
- */
-struct Error : public std::runtime_error {
-  /*!
-   * \brief constructor
-   * \param s the error message
-   */
-  explicit Error(const std::string& s) : std::runtime_error(s) {}
-};
-
 /*!
  * \brief Error type for errors from XGRAMMAR_CHECK, XGRAMMAR_ICHECK, and XGRAMMAR_LOG(FATAL). This
  * error contains a backtrace of where it occurred.
  */
-class InternalError : public Error {
+class Error : public std::runtime_error {
  public:
   /*! \brief Construct an error. Not recommended to use directly. Instead use XGRAMMAR_LOG(FATAL).
    *
    * \param file The file where the error occurred.
    * \param lineno The line number where the error occurred.
    * \param message The error message to display.
    * \param time The time at which the error occurred. This should be in local time.
-   * \param backtrace Backtrace from when the error occurred.
    */
-  InternalError(
-      std::string file, int lineno, std::string message, std::time_t time = std::time(nullptr)
-  )
-      : Error(""), file_(file), lineno_(lineno), message_(message), time_(time) {
+  Error(std::string file, int lineno, std::string message, std::time_t time = std::time(nullptr))
+      : std::runtime_error(""), file_(file), lineno_(lineno), message_(message), time_(time) {
     std::ostringstream s;
-    // XXX: Do not change this format, otherwise all error handling in python will break (because it
-    // parses the message to reconstruct the error type).
-    // TODO(tkonolige): Convert errors to Objects, so we can avoid the mess of formatting/parsing
-    // error messages correctly.
     s << "[" << std::put_time(std::localtime(&time), "%H:%M:%S") << "] " << file << ":" << lineno
       << ": " << message << std::endl;
     full_message_ = s.str();
   }
+
   /*! \return The file in which the error occurred. */
   const std::string& file() const { return file_; }
   /*! \return The message associated with this error. */
@@ -171,10 +153,7 @@ class LogFatal {
       this->lineno_ = lineno;
     }
     [[noreturn]] Error Finalize() noexcept(false) {
-      InternalError error(file_, lineno_, stream_.str());
-#if DMLC_LOG_BEFORE_THROW
-      std::cerr << error.what() << std::endl;
-#endif
+      Error error(file_, lineno_, stream_.str());
       throw error;
     }
     std::ostringstream stream_;
@@ -204,19 +183,17 @@ class LogMessage {
   static const char* level_strings_[];
 };
 
-#endif  // if XGRAMMAR_LOG_CUSTOMIZE
+#endif  // XGRAMMAR_LOG_CUSTOMIZE
 
-#define XGRAMMAR_LOG_LEVEL_DEBUG 0
-#define XGRAMMAR_LOG_LEVEL_INFO 1
+#define XGRAMMAR_LOG_LEVEL_INFO 0
+#define XGRAMMAR_LOG_LEVEL_DEBUG 1
 #define XGRAMMAR_LOG_LEVEL_WARNING 2
-#define XGRAMMAR_LOG_LEVEL_ERROR 3
-#define XGRAMMAR_LOG_LEVEL_FATAL 4
+#define XGRAMMAR_LOG_LEVEL_FATAL 3
 
-#define XGRAMMAR_LOG_DEBUG LogMessage(__FILE__, __LINE__, XGRAMMAR_LOG_LEVEL_DEBUG).stream()
-#define XGRAMMAR_LOG_FATAL LogFatal(__FILE__, __LINE__).stream()
 #define XGRAMMAR_LOG_INFO LogMessage(__FILE__, __LINE__, XGRAMMAR_LOG_LEVEL_INFO).stream()
-#define XGRAMMAR_LOG_ERROR LogMessage(__FILE__, __LINE__, XGRAMMAR_LOG_LEVEL_ERROR).stream()
+#define XGRAMMAR_LOG_DEBUG LogMessage(__FILE__, __LINE__, XGRAMMAR_LOG_LEVEL_DEBUG).stream()
 #define XGRAMMAR_LOG_WARNING LogMessage(__FILE__, __LINE__, XGRAMMAR_LOG_LEVEL_WARNING).stream()
+#define XGRAMMAR_LOG_FATAL LogFatal(__FILE__, __LINE__).stream()
 
 #define XGRAMMAR_LOG(level) XGRAMMAR_LOG_##level
 

web/src/xgrammar_binding.cc

@@ -26,10 +26,9 @@ namespace xgrammar {
 
 void LogMessageImpl(const std::string& file, int lineno, int level, const std::string& message) {
   static const char* level_strings_[] = {
-      "[DEBUG] ",
       "[INFO] ",
+      "[DEBUG] ",
       "[WARNING] ",
-      "[ERROR] ",
   };
   std::cout << level_strings_[level] << file << ":" << lineno << ": " << message << std::endl;
 }