ke/docs/CPP17_CONVERSION.md

C++17 Conversion Documentation

Overview

This document describes the initial conversion of the ke2 project from C to C++17 standards, starting with the abuf and erow structures as requested.

Converted Components

1. abuf (Append Buffer)

Original C Structure (main.c:69-73):

struct abuf {
    char *b;
    int len;
    int cap;
};

C++17 Implementation (abuf.hpp, abuf.cpp):

• Converted to a modern C++ class using RAII principles
• Uses std::string as the internal buffer for automatic memory management
• Implements move semantics (deleted copy operations)
• Uses C++17 features:
  • std::string_view for efficient string parameters
  • [[nodiscard]] attributes for better safety
  • noexcept specifications where appropriate
• No manual memory management required - destructor automatically handled by std::string

Key Improvements:

• Automatic memory cleanup (RAII)
• Exception-safe
• No memory leaks possible
• More efficient with move semantics
• Type-safe with modern C++ idioms

2. erow (Editor Row)

Original C Structure (main.c:79-87):

struct erow {
    char *line;
    char *render;
    int size;
    int rsize;
    int cap;
};

C++17 Implementation (erow.hpp, erow.cpp):

• Converted to a C++ class with proper encapsulation
• Uses std::string for both line and render buffers
• Implements move semantics (deleted copy operations)
• All manual memory management replaced with RAII
• Retains all original functionality:
  • UTF-8 character handling with mbrtowc and wcwidth
  • Tab expansion (TAB_STOP = 8)
  • Control character rendering as \xx
  • Cursor-to-render and render-to-cursor position conversions

Key Improvements:

• Automatic memory cleanup for both line and render buffers
• No malloc/free/realloc needed
• Exception-safe operations
• Better encapsulation with private members
• Modern C++ method naming conventions

Build System Updates

Makefile

• Added C++ compiler support (g++)
• Added CXXFLAGS with -std=c++17
• Modified build rules to compile C and C++ separately
• Updated to link with C++ compiler
• Enhanced clean target to remove object files

CMakeLists.txt

• Changed project language from C to C CXX
• Added CMAKE_CXX_STANDARD 17 and CMAKE_CXX_STANDARD_REQUIRED ON
• Added C++ compiler flags matching C flags
• Updated executable target to include abuf.cpp and erow.cpp
• Maintained backward compatibility with existing C code (main.c)

Compilation Testing

Both build systems have been tested and verified:

• ✅ Makefile: Successfully compiles with make
• ✅ CMake: Successfully configures and builds
• ✅ Object files generated correctly for all C++ sources
• ✅ No compilation warnings or errors

C++17 Features Used

1. std::string - Modern string class with automatic memory management
2. std::string_view - Efficient non-owning string references (C++17)
3. nodiscard - Compiler warnings for ignored return values (C++17)
4. noexcept - Exception specifications for optimization
5. default/delete - Explicit control over special member functions
6. Move semantics - Efficient resource transfer
7. constexpr - Compile-time constants (TAB_STOP)

Next Steps

The project now has a foundation for further C++17 conversion:

• Additional structures can be converted following the same patterns
• Consider converting more C code to C++ classes
• Potential for using more STL containers (std::vector for dynamic arrays)
• Opportunity to use smart pointers for other memory management
• Can leverage more C++17 features (std::optional, structured bindings, etc.)

Compatibility

• The new C++ code coexists with existing C code (main.c)
• Both can be compiled together and linked successfully
• The conversion maintains the original functionality
• No changes required to existing C code at this stage