Continue C++ rewrite.

CMakeLists.txt

@@ -1,30 +1,74 @@
+# CMake configuration for Kyle's Editor (ke)
 cmake_minimum_required(VERSION 3.15)
-project(ke C)  # Specify C language explicitly
+project(ke VERSION 1.3.3 LANGUAGES CXX)
 
-set(CMAKE_C_STANDARD 99)
+# Project metadata
 set(KE_VERSION "1.3.3")
 
-set(CMAKE_C_FLAGS "-Wall -Wextra -pedantic -Wshadow -Werror -std=c99 -g")
-set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -D_DEFAULT_SOURCE -D_XOPEN_SOURCE")
+# C++17 standard requirement
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_EXTENSIONS OFF)
 
-# Optionally enable AddressSanitizer (ASan)
+# Source files
+set(KE_SOURCES
+    main.cc
+    abuf.cc
+    erow.cc
+    terminal.cc
+    input_handler.cc
+    display.cc
+    file_io.cc
+    killring.cc
+)
+
+# Header files
+set(KE_HEADERS
+    ke_constants.h
+    abuf.h
+    erow.h
+    terminal.h
+    input_handler.h
+    display.h
+    file_io.h
+    killring.h
+)
+
+# Build options
 option(ENABLE_ASAN "Enable AddressSanitizer for builds" OFF)
 
+# Create executable target
+add_executable(ke ${KE_SOURCES})
+
+# Target compile features
+target_compile_features(ke PRIVATE cxx_std_17)
+
+# Target compile options
+target_compile_options(ke PRIVATE
+    -Wall
+    -Wextra
+    -pedantic
+    -Wshadow
+    -Werror
+    -g
+)
+
+# Target compile definitions
+target_compile_definitions(ke PRIVATE
+    KE_VERSION="ke version ${KE_VERSION}"
+    _DEFAULT_SOURCE
+    _XOPEN_SOURCE
+)
+
+# AddressSanitizer support
 if(ENABLE_ASAN)
     message(STATUS "ASan enabled")
-    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fsanitize=address -fno-omit-frame-pointer")
-    # Ensure the sanitizer is linked too (especially important on some platforms)
-    set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -fsanitize=address")
+    target_compile_options(ke PRIVATE -fsanitize=address -fno-omit-frame-pointer)
+    target_link_options(ke PRIVATE -fsanitize=address)
 endif()
 
+# Installation rules
 include(GNUInstallDirs)
-
-# Add executable
-add_executable(ke main.c)
-target_compile_definitions(ke PRIVATE KE_VERSION="ke version ${KE_VERSION}")
-install(TARGETS ke RUNTIME DESTINATION bin)
-install(FILES ke.1 TYPE MAN)
-
 install(TARGETS ke RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
 install(FILES ke.1 DESTINATION ${CMAKE_INSTALL_MANDIR}/man1)
 

Makefile

@@ -2,17 +2,53 @@ TARGET :=		ke
 KE_VERSION :=		devel
 DEST :=			$(HOME)/.local/bin/$(TARGET)
 
+CC :=		gcc
+CXX :=		g++
+
 CFLAGS :=	-Wall -Wextra -pedantic -Wshadow -Werror -std=c99 -g
 CFLAGS +=	-Wno-unused-result
 CFLAGS +=	-D_DEFAULT_SOURCE -D_XOPEN_SOURCE
 CFLAGS +=	-fsanitize=address -fno-omit-frame-pointer 
 
+CXXFLAGS :=	-Wall -Wextra -pedantic -Wshadow -Werror -std=c++17 -g
+CXXFLAGS +=	-Wno-unused-result
+CXXFLAGS +=	-D_DEFAULT_SOURCE -D_XOPEN_SOURCE
+CXXFLAGS +=	-DKE_VERSION='"ke $(KE_VERSION)"'
+CXXFLAGS +=	-fsanitize=address -fno-omit-frame-pointer
+
 LDFLAGS :=	-fsanitize=address
 
+SOURCES :=	main.cc abuf.cc erow.cc terminal.cc input_handler.cc display.cc file_io.cc killring.cc
+OBJECTS :=	main.o abuf.o erow.o terminal.o input_handler.o display.o file_io.o killring.o
+
 all: $(TARGET) test.txt
 
-$(TARGET): main.c
-	$(CC) $(CFLAGS) -o $(TARGET) $(LDFLAGS) main.c
+$(TARGET): $(OBJECTS)
+	$(CXX) $(CXXFLAGS) -o $(TARGET) $(OBJECTS) $(LDFLAGS)
+
+main.o: main.cc ke_constants.h
+	$(CXX) $(CXXFLAGS) -c main.cc
+
+abuf.o: abuf.cc abuf.h
+	$(CXX) $(CXXFLAGS) -c abuf.cc
+
+erow.o: erow.cc erow.h
+	$(CXX) $(CXXFLAGS) -c erow.cc
+
+terminal.o: terminal.cc terminal.h
+	$(CXX) $(CXXFLAGS) -c terminal.cc
+
+input_handler.o: input_handler.cc input_handler.h ke_constants.h
+	$(CXX) $(CXXFLAGS) -c input_handler.cc
+
+display.o: display.cc display.h ke_constants.h
+	$(CXX) $(CXXFLAGS) -c display.cc
+
+file_io.o: file_io.cc file_io.h
+	$(CXX) $(CXXFLAGS) -c file_io.cc
+
+killring.o: killring.cc killring.h
+	$(CXX) $(CXXFLAGS) -c killring.cc
 
 .PHONY: install
 #install: $(TARGET) 
@@ -21,6 +57,7 @@ install:
 
 clean:
 	rm -f $(TARGET)
+	rm -f $(OBJECTS)
 	rm -f asan.log*
 
 .PHONY: test.txt

abuf.cc

@@ -0,0 +1,17 @@
+#include "abuf.h"
+
+namespace ke {
+
+void abuf::append(std::string_view s) {
+    buffer_.append(s);
+}
+
+void abuf::append(const char* s, std::size_t len) {
+    buffer_.append(s, len);
+}
+
+void abuf::append(char c) {
+    buffer_.push_back(c);
+}
+
+} // namespace ke

abuf.h

@@ -0,0 +1,57 @@
+#ifndef ABUF_HPP
+#define ABUF_HPP
+
+#include <string>
+#include <string_view>
+#include <cstddef>
+
+namespace ke {
+
+/**
+ * Append buffer class for efficient string building.
+ * C++17 implementation with RAII memory management.
+ */
+class abuf {
+public:
+    // Constructors
+    abuf() noexcept = default;
+    
+    // Deleted copy constructor and assignment (use move semantics)
+    abuf(const abuf&) = delete;
+    abuf& operator=(const abuf&) = delete;
+    
+    // Move constructor and assignment
+    abuf(abuf&&) noexcept = default;
+    abuf& operator=(abuf&&) noexcept = default;
+    
+    // Destructor (automatic cleanup via std::string)
+    ~abuf() = default;
+    
+    // Append methods
+    void append(std::string_view s);
+    void append(const char* s, std::size_t len);
+    void append(char c);
+    
+    // Accessors
+    [[nodiscard]] const char* data() const noexcept { return buffer_.data(); }
+    [[nodiscard]] std::size_t size() const noexcept { return buffer_.size(); }
+    [[nodiscard]] std::size_t length() const noexcept { return buffer_.length(); }
+    [[nodiscard]] bool empty() const noexcept { return buffer_.empty(); }
+    [[nodiscard]] std::size_t capacity() const noexcept { return buffer_.capacity(); }
+    
+    // Get the underlying string
+    [[nodiscard]] const std::string& str() const noexcept { return buffer_; }
+    
+    // Clear the buffer
+    void clear() noexcept { buffer_.clear(); }
+    
+    // Reserve capacity
+    void reserve(std::size_t new_cap) { buffer_.reserve(new_cap); }
+
+private:
+    std::string buffer_;
+};
+
+} // namespace ke
+
+#endif // ABUF_HPP

display.cc

@@ -0,0 +1,237 @@
+#include "display.h"
+#include "ke_constants.h"
+#include "abuf.h"
+#include "erow.h"
+#include <termios.h>
+#include <unistd.h>
+#include <cstdio>
+#include <cstring>
+#include <ctime>
+#include <cassert>
+
+// Need access to main.cc structures and functions
+extern void erow_update(struct erow *row);
+extern int erow_render_to_cursor(struct erow *row, int cx);
+
+// erow definition (needed for accessing row fields)
+struct erow {
+	char *line;
+	char *render;
+	int size;
+	int rsize;
+	int cap;
+};
+
+// editor_t definition (needed for display operations)
+struct editor_t {
+	struct termios entry_term;
+	int rows, cols;
+	int curx, cury;
+	int rx;
+	int mode;
+	int nrows;
+	int rowoffs, coloffs;
+	struct erow *row;
+	struct erow *killring;
+	int kill;
+	int no_kill;
+	char *filename;
+	int dirty;
+	int dirtyex;
+	char msg[80];
+	int mark_set;
+	int mark_curx, mark_cury;
+	time_t msgtm;
+};
+
+namespace ke {
+
+void Display::clear(ke::abuf* ab) {
+    if (ab == nullptr) {
+        (void)write(STDOUT_FILENO, ESCSEQ "2J", 4);
+        (void)write(STDOUT_FILENO, ESCSEQ "H", 3);
+    } else {
+        ab->append(ESCSEQ "2J", 4);
+        ab->append(ESCSEQ "H", 3);
+    }
+}
+
+void Display::draw_rows(editor_t* editor, ke::abuf* ab) {
+    assert(editor->cols >= 0);
+    
+    char* buf = new char[editor->cols];
+    int buflen, filerow, padding;
+    int y;
+    
+    for (y = 0; y < editor->rows; y++) {
+        filerow = y + editor->rowoffs;
+        if (filerow >= editor->nrows) {
+            if ((editor->nrows == 0) && (y == editor->rows / 3)) {
+                buflen = snprintf(buf,
+                                  editor->cols,
+                                  "%s",
+                                  KE_VERSION);
+                padding = (editor->rows - buflen) / 2;
+                
+                if (padding) {
+                    ab->append("|", 1);
+                    padding--;
+                }
+                
+                while (padding--)
+                    ab->append(" ", 1);
+                ab->append(buf, buflen);
+            } else {
+                ab->append("|", 1);
+            }
+        } else {
+            erow_update(&editor->row[filerow]);
+            buflen = editor->row[filerow].rsize - editor->coloffs;
+            if (buflen < 0) {
+                buflen = 0;
+            }
+            
+            if (buflen > editor->cols) {
+                buflen = editor->cols;
+            }
+            ab->append(editor->row[filerow].render + editor->coloffs,
+                       buflen);
+        }
+        ab->append(ESCSEQ "K", 3);
+        ab->append("\r\n", 2);
+    }
+    delete[] buf;
+}
+
+char Display::status_mode_char(int mode) {
+    switch (mode) {
+        case MODE_NORMAL:
+            return 'N';
+        case MODE_KCOMMAND:
+            return 'K';
+        case MODE_ESCAPE:
+            return 'E';
+        default:
+            return '?';
+    }
+}
+
+void Display::draw_status_bar(editor_t* editor, ke::abuf* ab) {
+    char* status = new char[editor->cols];
+    char* rstatus = new char[editor->cols];
+    char* mstatus = new char[editor->cols];
+    
+    int len, rlen;
+    
+    len = snprintf(status,
+                   editor->cols,
+                   "%c%cke: %.20s - %d lines",
+                   status_mode_char(editor->mode),
+                   editor->dirty ? '!' : '-',
+                   editor->filename ? editor->filename : "[no file]",
+                   editor->nrows);
+    
+    if (editor->mark_set) {
+        snprintf(mstatus,
+                 editor->cols,
+                 " | M: %d, %d ",
+                 editor->mark_curx + 1,
+                 editor->mark_cury + 1);
+    } else {
+        snprintf(mstatus, editor->cols, " | M:clear ");
+    }
+    
+    rlen = snprintf(rstatus,
+                    editor->cols,
+                    "L%d/%d C%d %s",
+                    editor->cury + 1,
+                    editor->nrows,
+                    editor->curx + 1,
+                    mstatus);
+    
+    if (len > editor->cols) {
+        len = editor->cols;
+    }
+    
+    ab->append(ESCSEQ "7m", 4);
+    ab->append(status, len);
+    while (len < editor->cols) {
+        if (editor->cols - len == rlen) {
+            ab->append(rstatus, rlen);
+            break;
+        } else {
+            ab->append(" ", 1);
+            len++;
+        }
+        len++;
+    }
+    ab->append(ESCSEQ "m", 3);
+    ab->append("\r\n", 2);
+    delete[] status;
+    delete[] rstatus;
+    delete[] mstatus;
+}
+
+void Display::draw_message_line(editor_t* editor, ke::abuf* ab) {
+    int len = strlen(editor->msg);
+    
+    ab->append(ESCSEQ "K", 3);
+    if (len > editor->cols) {
+        len = editor->cols;
+    }
+    
+    if (len && ((time(nullptr) - editor->msgtm) < MSG_TIMEO)) {
+        ab->append(editor->msg, len);
+    }
+}
+
+void Display::scroll(editor_t* editor) {
+    editor->rx = 0;
+    if (editor->cury < editor->nrows) {
+        editor->rx = erow_render_to_cursor(
+            &editor->row[editor->cury],
+            editor->curx);
+    }
+    
+    if (editor->cury < editor->rowoffs) {
+        editor->rowoffs = editor->cury;
+    }
+    
+    if (editor->cury >= editor->rowoffs + editor->rows) {
+        editor->rowoffs = editor->cury - editor->rows + 1;
+    }
+    
+    if (editor->rx < editor->coloffs) {
+        editor->coloffs = editor->rx;
+    }
+    
+    if (editor->rx >= editor->coloffs + editor->cols) {
+        editor->coloffs = editor->rx - editor->cols + 1;
+    }
+}
+
+void Display::refresh(editor_t* editor) {
+    char buf[32];
+    ke::abuf ab;
+    
+    scroll(editor);
+    
+    ab.append(ESCSEQ "?25l", 6);
+    clear(&ab);
+    
+    draw_rows(editor, &ab);
+    draw_status_bar(editor, &ab);
+    draw_message_line(editor, &ab);
+    
+    snprintf(buf,
+             sizeof(buf),
+             ESCSEQ "%d;%dH",
+             (editor->cury - editor->rowoffs) + 1,
+             (editor->rx - editor->coloffs) + 1);
+    ab.append(buf, strnlen(buf, 32));
+    ab.append(ESCSEQ "?25h", 6);
+    
+    (void)write(STDOUT_FILENO, ab.data(), ab.size());
+}
+
+} // namespace ke

display.h

@@ -0,0 +1,42 @@
+#ifndef DISPLAY_HPP
+#define DISPLAY_HPP
+
+#include <cstddef>
+
+// Forward declarations
+struct editor_t;
+
+namespace ke {
+    class abuf;  // Forward declaration of ke::abuf
+
+/**
+ * Display class for screen rendering and refresh operations.
+ */
+class Display {
+public:
+    Display() = default;
+    ~Display() = default;
+    
+    // Deleted copy constructor and assignment
+    Display(const Display&) = delete;
+    Display& operator=(const Display&) = delete;
+    
+    // Main display operations
+    static void refresh(editor_t* editor);
+    static void clear(ke::abuf* ab);
+    
+    // Drawing operations
+    static void draw_rows(editor_t* editor, ke::abuf* ab);
+    static void draw_status_bar(editor_t* editor, ke::abuf* ab);
+    static void draw_message_line(editor_t* editor, ke::abuf* ab);
+    
+    // Scrolling
+    static void scroll(editor_t* editor);
+    
+private:
+    static char status_mode_char(int mode);
+};
+
+} // namespace ke
+
+#endif // DISPLAY_HPP

docs/CONSTANTS_REFACTORING.md

@@ -0,0 +1,115 @@
+# Constants Refactoring Documentation
+
+## Overview
+This document describes the refactoring of #defines and common constants into a single centralized header file for Kyle's Editor (ke).
+
+## Changes Made
+
+### 1. Created `ke_constants.h`
+A new header file was created to centralize all common constants and preprocessor definitions used throughout the project.
+
+**Location**: `/Users/kyle/src/ke2/ke_constants.h`
+
+**Contents**:
+- **Version Information**: `KE_VERSION` - Editor version string
+- **Terminal Sequences**: `ESCSEQ` - ANSI escape sequence prefix
+- **Keyboard Macros**: `CTRL_KEY(key)` - Control key combination macro
+- **Display Constants**: 
+  - `TAB_STOP` (8) - Tab stop width
+  - `MSG_TIMEO` (3) - Message timeout in seconds
+- **Memory Management**: `INITIAL_CAPACITY` (64) - Initial buffer capacity
+- **Keyboard Modes**:
+  - `MODE_NORMAL` (0) - Normal editing mode
+  - `MODE_KCOMMAND` (1) - Command mode (^k commands)
+  - `MODE_ESCAPE` (2) - Escape key handling mode
+- **Kill Ring Operations**:
+  - `KILLRING_NO_OP` (0) - No operation
+  - `KILLRING_APPEND` (1) - Append deleted characters
+  - `KILLRING_PREPEND` (2) - Prepend deleted characters
+  - `KILLING_SET` (3) - Set killring to deleted character
+  - `KILLRING_FLUSH` (4) - Clear the killring
+- **Legacy Initializers**: `ABUF_INIT` - C struct initializer for append buffer
+
+### 2. Updated `main.c`
+- Added `#include "ke_constants.h"` at the top with other includes
+- Removed all duplicate #define statements that were moved to the constants header
+- Eliminated the duplicate `TAB_STOP` definition (was defined twice on lines 36 and 50)
+- Cleaned up approximately 30+ lines of redundant definitions
+
+### 3. Updated `erow.cpp`
+- Added `#include "ke_constants.h"` with extern "C" linkage for C++ compatibility
+- Removed local `constexpr int TAB_STOP = 8` definition
+- Now uses the centralized `TAB_STOP` constant from `ke_constants.h`
+
+## Benefits
+
+1. **Single Source of Truth**: All constants are now defined in one location, making them easier to maintain and modify
+2. **Eliminated Duplication**: Removed duplicate definitions (e.g., TAB_STOP was defined twice in main.c)
+3. **Better Organization**: Constants are grouped logically by category with clear comments
+4. **Cross-Language Compatibility**: Header works with both C (main.c) and C++ (erow.cpp) code
+5. **Easier Maintenance**: Future changes to constants only need to be made in one place
+6. **Improved Readability**: Cleaner source files with less clutter from #define statements
+
+## Build System Compatibility
+
+Both build systems have been tested and verified to work correctly:
+
+### Makefile Build
+```bash
+make clean
+make
+```
+Successfully compiles all files (main.c, abuf.cpp, erow.cpp) and links the executable.
+
+### CMake Build
+```bash
+cd cmake-build-debug
+cmake --build . --clean-first
+```
+Successfully builds the project with all components.
+
+## Header Guard
+The header uses standard include guards:
+```c
+#ifndef KE_CONSTANTS_H
+#define KE_CONSTANTS_H
+...
+#endif /* KE_CONSTANTS_H */
+```
+
+## C/C++ Interoperability
+When including in C++ files, use extern "C" linkage:
+```cpp
+extern "C" {
+#include "ke_constants.h"
+}
+```
+
+This ensures proper linkage and prevents name mangling issues.
+
+## Future Considerations
+
+1. **Additional Constants**: As the project grows, any new constants should be added to `ke_constants.h` rather than being scattered across source files
+2. **Namespacing**: For C++ constants, consider creating a dedicated C++ header with namespaced constants
+3. **Type Safety**: For C++ code, consider using `constexpr` or `inline constexpr` variables in a C++ header for better type safety
+4. **Documentation**: Keep this document updated as new constants are added or modified
+
+## Testing
+
+All compilation tests passed:
+- ✅ Makefile build: Clean compilation with no errors or warnings
+- ✅ CMake build: Clean compilation with no errors or warnings
+- ✅ All source files (C and C++) successfully include and use the constants
+- ✅ No duplicate definition errors
+- ✅ Proper linkage between C and C++ components
+
+## Related Files
+
+- `ke_constants.h` - The new constants header (created)
+- `main.c` - Updated to use new header (modified)
+- `erow.cpp` - Updated to use new header (modified)
+- `Makefile` - No changes required (working)
+- `CMakeLists.txt` - No changes required (working)
+
+## Date
+November 24, 2025

docs/CPP17_CONVERSION.md

@@ -0,0 +1,109 @@
+# 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):**
+```c
+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):**
+```c
+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

erow.cc

@@ -0,0 +1,214 @@
+#include "erow.h"
+#include <cstring>
+#include <cwchar>
+#include <cassert>
+
+#include "ke_constants.h"
+
+namespace ke {
+
+// Constructors
+erow::erow(std::size_t initial_capacity) {
+    line_.reserve(initial_capacity);
+}
+
+erow::erow(const char* text, std::size_t len) {
+    line_.assign(text, len);
+}
+
+// Set line content
+void erow::set_line(const char* data, std::size_t len) {
+    line_.assign(data, len);
+}
+
+// Append string to the line
+void erow::append_string(const char* s, std::size_t len) {
+    line_.append(s, len);
+}
+
+// Insert character at position
+void erow::insert_char(std::size_t at, char c) {
+    if (at > line_.size()) {
+        at = line_.size();
+    }
+    line_.insert(at, 1, c);
+}
+
+// Delete character at position
+void erow::delete_char(std::size_t at) {
+    if (at < line_.size()) {
+        line_.erase(at, 1);
+    }
+}
+
+// Helper function for nibble to hex conversion
+char erow::nibble_to_hex(char c) {
+    c &= 0xf;
+    if (c < 10) {
+        return static_cast<char>('0' + c);
+    }
+    return static_cast<char>('A' + (c - 10));
+}
+
+// Update the render string based on the line content
+void erow::update() {
+    int tabs = 0;
+    int ctrl = 0;
+    
+    // Count tabs and control characters
+    for (std::size_t j = 0; j < line_.size(); ++j) {
+        if (line_[j] == '\t') {
+            ++tabs;
+        } else if (static_cast<unsigned char>(line_[j]) < 0x20) {
+            ++ctrl;
+        }
+    }
+    
+    // Allocate render buffer
+    render_.clear();
+    render_.reserve(line_.size() + (tabs * (TAB_STOP - 1)) + (ctrl * 3) + 1);
+    
+    // Build the render string
+    for (std::size_t j = 0; j < line_.size(); ++j) {
+        if (line_[j] == '\t') {
+            // Expand tabs to spaces
+            do {
+                render_.push_back(' ');
+            } while ((render_.size() % TAB_STOP) != 0);
+        } else if (static_cast<unsigned char>(line_[j]) < 0x20) {
+            // Render control characters as \xx
+            render_.push_back('\\');
+            render_.push_back(nibble_to_hex(line_[j] >> 4));
+            render_.push_back(nibble_to_hex(line_[j] & 0x0f));
+        } else {
+            // Leave UTF-8 multibyte bytes untouched
+            render_.push_back(line_[j]);
+        }
+    }
+}
+
+// Convert cursor position to render position
+int erow::render_to_cursor(int cx) const {
+    int rx = 0;
+    std::size_t j = 0;
+    
+    wchar_t wc;
+    std::mbstate_t st{};
+    
+    while (j < static_cast<std::size_t>(cx) && j < line_.size()) {
+        unsigned char b = static_cast<unsigned char>(line_[j]);
+        
+        if (b == '\t') {
+            rx += (TAB_STOP - 1) - (rx % TAB_STOP);
+            ++rx;
+            ++j;
+            continue;
+        }
+        
+        if (b < 0x20) {
+            // Render as \xx -> width 3
+            rx += 3;
+            ++j;
+            continue;
+        }
+        
+        std::size_t rem = line_.size() - j;
+        std::size_t n = std::mbrtowc(&wc, &line_[j], rem, &st);
+        
+        if (n == static_cast<std::size_t>(-2)) {
+            // Incomplete sequence at end; treat one byte
+            rx += 1;
+            j += 1;
+            std::memset(&st, 0, sizeof(st));
+        } else if (n == static_cast<std::size_t>(-1)) {
+            // Invalid byte; consume one and reset state
+            rx += 1;
+            j += 1;
+            std::memset(&st, 0, sizeof(st));
+        } else if (n == 0) {
+            // Null character
+            rx += 0;
+            j += 1;
+        } else {
+            int w = wcwidth(wc);
+            if (w < 0) {
+                w = 1; // Non-printable -> treat as width 1
+            }
+            rx += w;
+            j += n;
+        }
+    }
+    
+    return rx;
+}
+
+// Convert render position to cursor position
+int erow::cursor_to_render(int rx) const {
+    int cur_rx = 0;
+    std::size_t j = 0;
+    
+    wchar_t wc;
+    std::mbstate_t st{};
+    
+    while (j < line_.size()) {
+        unsigned char b = static_cast<unsigned char>(line_[j]);
+        
+        if (b == '\t') {
+            int tab_width = (TAB_STOP - 1) - (cur_rx % TAB_STOP) + 1;
+            if (cur_rx + tab_width > rx) {
+                break;
+            }
+            cur_rx += tab_width;
+            ++j;
+            continue;
+        }
+        
+        if (b < 0x20) {
+            // Control char width is 3
+            if (cur_rx + 3 > rx) {
+                break;
+            }
+            cur_rx += 3;
+            ++j;
+            continue;
+        }
+        
+        std::size_t rem = line_.size() - j;
+        std::size_t n = std::mbrtowc(&wc, &line_[j], rem, &st);
+        std::size_t adv = 1;
+        int w = 1;
+        
+        if (n == static_cast<std::size_t>(-2)) {
+            // Incomplete sequence
+            adv = 1;
+            w = 1;
+            std::memset(&st, 0, sizeof(st));
+        } else if (n == static_cast<std::size_t>(-1)) {
+            // Invalid byte
+            adv = 1;
+            w = 1;
+            std::memset(&st, 0, sizeof(st));
+        } else if (n == 0) {
+            // Null character
+            adv = 1;
+            w = 0;
+        } else {
+            adv = n;
+            w = wcwidth(wc);
+            if (w < 0) {
+                w = 1;
+            }
+        }
+        
+        if (cur_rx + w > rx) {
+            break;
+        }
+        
+        cur_rx += w;
+        j += adv;
+    }
+    
+    return static_cast<int>(j);
+}
+
+} // namespace ke

erow.h

@@ -0,0 +1,76 @@
+#ifndef EROW_HPP
+#define EROW_HPP
+
+#include <string>
+#include <memory>
+#include <cstddef>
+#include <cstdint>
+
+namespace ke {
+
+/**
+ * Editor row class representing a line of text with rendering information.
+ * C++17 implementation with RAII memory management.
+ */
+class erow {
+public:
+    // Constructors
+    erow() noexcept = default;
+    explicit erow(std::size_t initial_capacity);
+    erow(const char* text, std::size_t len);
+    
+    // Deleted copy constructor and assignment (use move semantics)
+    erow(const erow&) = delete;
+    erow& operator=(const erow&) = delete;
+    
+    // Move constructor and assignment
+    erow(erow&&) noexcept = default;
+    erow& operator=(erow&&) noexcept = default;
+    
+    // Destructor (automatic cleanup via std::string)
+    ~erow() = default;
+    
+    // Core operations
+    void update();
+    void insert_char(std::size_t at, char c);
+    void delete_char(std::size_t at);
+    void append_string(const char* s, std::size_t len);
+    
+    // Cursor/render position conversions
+    [[nodiscard]] int render_to_cursor(int cx) const;
+    [[nodiscard]] int cursor_to_render(int rx) const;
+    
+    // Accessors for line data
+    [[nodiscard]] const char* line_data() const noexcept { return line_.data(); }
+    [[nodiscard]] char* line_data() noexcept { return line_.data(); }
+    [[nodiscard]] std::size_t line_size() const noexcept { return line_.size(); }
+    [[nodiscard]] std::size_t line_capacity() const noexcept { return line_.capacity(); }
+    
+    // Accessors for render data
+    [[nodiscard]] const char* render_data() const noexcept { return render_.data(); }
+    [[nodiscard]] std::size_t render_size() const noexcept { return render_.size(); }
+    
+    // Direct access to strings (for compatibility)
+    [[nodiscard]] std::string& line() noexcept { return line_; }
+    [[nodiscard]] const std::string& line() const noexcept { return line_; }
+    [[nodiscard]] const std::string& render() const noexcept { return render_; }
+    
+    // Resize operations
+    void resize_line(std::size_t new_size) { line_.resize(new_size); }
+    void reserve_line(std::size_t new_cap) { line_.reserve(new_cap); }
+    
+    // Set line content
+    void set_line(const char* data, std::size_t len);
+    void set_line(std::string&& data) noexcept { line_ = std::move(data); }
+
+private:
+    std::string line_;    // The actual line content
+    std::string render_;  // The rendered version (with tabs expanded, etc.)
+    
+    // Helper for nibble to hex conversion
+    static char nibble_to_hex(char c);
+};
+
+} // namespace ke
+
+#endif // EROW_HPP

file_io.cc

@@ -0,0 +1,180 @@
+#include "file_io.h"
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <termios.h>
+#include <cerrno>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <cassert>
+#include <ctime>
+
+// Need access to main.cc structures and functions
+extern void erow_insert(int at, const char *s, int len);
+extern void reset_editor();
+extern void editor_set_status(const char *fmt, ...);
+extern void die(const char *s);
+extern char *editor_prompt(const char *, void (*cb)(char *, int16_t));
+
+// erow definition
+struct erow {
+	char *line;
+	char *render;
+	int size;
+	int rsize;
+	int cap;
+};
+
+// editor_t definition
+struct editor_t {
+	struct termios entry_term;
+	int rows, cols;
+	int curx, cury;
+	int rx;
+	int mode;
+	int nrows;
+	int rowoffs, coloffs;
+	struct erow *row;
+	struct erow *killring;
+	int kill;
+	int no_kill;
+	char *filename;
+	int dirty;
+	int dirtyex;
+	char msg[80];
+	int mark_set;
+	int mark_curx, mark_cury;
+	time_t msgtm;
+};
+
+namespace ke {
+
+void FileIO::open_file(editor_t* editor, const char* filename) {
+    char* line = nullptr;
+    size_t linecap = 0;
+    ssize_t linelen;
+    FILE* fp = nullptr;
+    
+    reset_editor();
+    
+    editor->filename = strdup(filename);
+    assert(editor->filename != nullptr);
+    
+    editor->dirty = 0;
+    if ((fp = fopen(filename, "r")) == nullptr) {
+        if (errno == ENOENT) {
+            editor_set_status("[new file]");
+            return;
+        }
+        die("fopen");
+    }
+    
+    while ((linelen = getline(&line, &linecap, fp)) != -1) {
+        if (linelen != -1) {
+            while ((linelen > 0) && ((line[linelen - 1] == '\r') ||
+                                     (line[linelen - 1] == '\n'))) {
+                linelen--;
+            }
+            
+            erow_insert(editor->nrows, line, linelen);
+        }
+    }
+    
+    free(line);
+    line = nullptr;
+    fclose(fp);
+}
+
+char* FileIO::rows_to_buffer(editor_t* editor, int* buflen) {
+    int len = 0;
+    int j;
+    char* buf = nullptr;
+    char* p = nullptr;
+    
+    for (j = 0; j < editor->nrows; j++) {
+        /* extra byte for newline */
+        len += editor->row[j].size + 1;
+    }
+    
+    if (len == 0) {
+        return nullptr;
+    }
+    
+    *buflen = len;
+    buf = static_cast<char*>(malloc(len));
+    assert(buf != nullptr);
+    p = buf;
+    
+    for (j = 0; j < editor->nrows; j++) {
+        memcpy(p, editor->row[j].line, editor->row[j].size);
+        p += editor->row[j].size;
+        *p++ = '\n';
+    }
+    
+    return buf;
+}
+
+int FileIO::save_file(editor_t* editor) {
+    int fd = -1;
+    int len;
+    int status = 1; /* will be used as exit code */
+    char* buf;
+    
+    if (!editor->dirty) {
+        editor_set_status("No changes to save.");
+        return 0;
+    }
+    
+    if (editor->filename == nullptr) {
+        editor->filename = editor_prompt("Filename: %s", nullptr);
+        if (editor->filename == nullptr) {
+            editor_set_status("Save aborted.");
+            return 0;
+        }
+    }
+    
+    buf = rows_to_buffer(editor, &len);
+    if ((fd = open(editor->filename, O_RDWR | O_CREAT, 0644)) == -1) {
+        goto save_exit;
+    }
+    
+    if (-1 == ftruncate(fd, len)) {
+        goto save_exit;
+    }
+    
+    if (len == 0) {
+        status = 0;
+        goto save_exit;
+    }
+    
+    if ((ssize_t) len != write(fd, buf, len)) {
+        goto save_exit;
+    }
+    
+    status = 0;
+    
+save_exit:
+    if (fd)
+        close(fd);
+    if (buf) {
+        free(buf);
+        buf = nullptr;
+    }
+    
+    if (status != 0) {
+        buf = strerror(errno);
+        editor_set_status("Error writing %s: %s",
+                          editor->filename,
+                          buf);
+    } else {
+        editor_set_status("Wrote %d bytes to %s.",
+                          len,
+                          editor->filename);
+        editor->dirty = 0;
+    }
+    
+    return status;
+}
+
+} // namespace ke

file_io.h

@@ -0,0 +1,29 @@
+#ifndef FILE_IO_HPP
+#define FILE_IO_HPP
+
+// Forward declaration
+struct editor_t;
+
+namespace ke {
+
+/**
+ * File I/O class for reading and writing files.
+ */
+class FileIO {
+public:
+    FileIO() = default;
+    ~FileIO() = default;
+    
+    // Deleted copy constructor and assignment
+    FileIO(const FileIO&) = delete;
+    FileIO& operator=(const FileIO&) = delete;
+    
+    // File operations
+    static void open_file(editor_t* editor, const char* filename);
+    static int save_file(editor_t* editor);
+    static char* rows_to_buffer(editor_t* editor, int* buflen);
+};
+
+} // namespace ke
+
+#endif // FILE_IO_HPP

input_handler.cc

@@ -0,0 +1,122 @@
+#include "input_handler.h"
+#include "ke_constants.h"
+#include <unistd.h>
+#include <cstdio>
+#include <cstdlib>
+
+namespace ke {
+
+// Key codes for special keys
+enum KeyPress {
+    TAB_KEY = 9,
+    ESC_KEY = 27,
+    BACKSPACE = 127,
+    ARROW_LEFT = 1000,
+    ARROW_RIGHT,
+    ARROW_UP,
+    ARROW_DOWN,
+    DEL_KEY,
+    HOME_KEY,
+    END_KEY,
+    PG_UP,
+    PG_DN,
+};
+
+int16_t InputHandler::get_keypress() {
+    char seq[3];
+    /* read raw byte so UTF-8 bytes (>=0x80) are not sign-extended */
+    unsigned char uc = 0;
+    int16_t c;
+    
+    if (read(STDIN_FILENO, &uc, 1) == -1) {
+        perror("get_keypress:read");
+        exit(1);
+    }
+    
+    c = (int16_t) uc;
+    
+    if (c == 0x1b) {
+        if (read(STDIN_FILENO, &seq[0], 1) != 1)
+            return c;
+        if (read(STDIN_FILENO, &seq[1], 1) != 1)
+            return c;
+        
+        if (seq[0] == '[') {
+            if (seq[1] < 'A') {
+                if (read(STDIN_FILENO, &seq[2], 1) != 1)
+                    return c;
+                if (seq[2] == '~') {
+                    switch (seq[1]) {
+                        case '1':
+                            return HOME_KEY;
+                        case '3':
+                            return DEL_KEY;
+                        case '4':
+                            return END_KEY;
+                        case '5':
+                            return PG_UP;
+                        case '6':
+                            return PG_DN;
+                        case '7':
+                            return HOME_KEY;
+                        case '8':
+                            return END_KEY;
+                    }
+                }
+            } else {
+                switch (seq[1]) {
+                    case 'A':
+                        return ARROW_UP;
+                    case 'B':
+                        return ARROW_DOWN;
+                    case 'C':
+                        return ARROW_RIGHT;
+                    case 'D':
+                        return ARROW_LEFT;
+                    case 'F':
+                        return END_KEY;
+                    case 'H':
+                        return HOME_KEY;
+                    
+                    default:
+                        /* nada */ ;
+                }
+            }
+        } else if (seq[0] == 'O') {
+            switch (seq[1]) {
+                case 'F':
+                    return END_KEY;
+                case 'H':
+                    return HOME_KEY;
+            }
+        }
+        
+        return 0x1b;
+    }
+    
+    return c;
+}
+
+bool InputHandler::is_arrow_key(int16_t c) {
+    switch (c) {
+        case ARROW_DOWN:
+        case ARROW_LEFT:
+        case ARROW_RIGHT:
+        case ARROW_UP:
+        case CTRL_KEY('p'):
+        case CTRL_KEY('n'):
+        case CTRL_KEY('f'):
+        case CTRL_KEY('b'):
+        case CTRL_KEY('a'):
+        case CTRL_KEY('e'):
+        case END_KEY:
+        case HOME_KEY:
+        case PG_DN:
+        case PG_UP:
+            return true;
+    }
+    
+    return false;
+}
+
+} // namespace ke

input_handler.h

@@ -0,0 +1,29 @@
+#ifndef INPUT_HANDLER_HPP
+#define INPUT_HANDLER_HPP
+
+#include <cstdint>
+
+namespace ke {
+
+/**
+ * Input handler class for reading and processing keyboard input.
+ */
+class InputHandler {
+public:
+    InputHandler() = default;
+    ~InputHandler() = default;
+    
+    // Deleted copy constructor and assignment
+    InputHandler(const InputHandler&) = delete;
+    InputHandler& operator=(const InputHandler&) = delete;
+    
+    // Read a keypress from stdin
+    static int16_t get_keypress();
+    
+    // Check if a key code is an arrow/navigation key
+    static bool is_arrow_key(int16_t c);
+};
+
+} // namespace ke
+
+#endif // INPUT_HANDLER_HPP

ke_constants.h

@@ -0,0 +1,44 @@
+/*
+ * ke_constants.h
+ * 
+ * Common constants and defines for Kyle's Editor (ke)
+ * Refactored from main.c and other source files for centralized maintenance.
+ */
+
+#ifndef KE_CONSTANTS_H
+#define KE_CONSTANTS_H
+
+/* Version information */
+#ifndef KE_VERSION
+#define KE_VERSION		"ke dev build"
+#endif
+
+/* Terminal escape sequences */
+#define ESCSEQ			"\x1b["
+
+/* Keyboard and control key macros */
+#define CTRL_KEY(key)		((key)&0x1f)
+
+/* Display and rendering constants */
+#define TAB_STOP		8
+#define MSG_TIMEO		3
+
+/* Memory management constants */
+#define INITIAL_CAPACITY	64
+
+/* Keyboard input modes */
+#define MODE_NORMAL		0
+#define MODE_KCOMMAND		1
+#define MODE_ESCAPE		2
+
+/* Kill ring operations */
+#define KILLRING_NO_OP		0	/* don't touch the killring */
+#define KILLRING_APPEND		1	/* append deleted chars */
+#define KILLRING_PREPEND	2	/* prepend deleted chars */
+#define KILLING_SET		3	/* set killring to deleted char */
+#define KILLRING_FLUSH		4	/* clear the killring */
+
+/* Legacy C struct initializers (for compatibility with main.c) */
+#define ABUF_INIT		{NULL, 0, 0}
+
+#endif /* KE_CONSTANTS_H */

killring.cc

@@ -0,0 +1,262 @@
+#include "killring.h"
+#include <termios.h>
+#include <cstdlib>
+#include <cstring>
+#include <cassert>
+#include <ctime>
+
+// Need access to main.cc structures and functions
+extern int erow_init(struct erow *row, int len);
+extern void erow_update(struct erow *row);
+extern void erow_free(struct erow *row);
+extern void editor_set_status(const char *fmt, ...);
+extern void insertch(int16_t c);
+extern void newline();
+extern void move_cursor(int16_t c);
+extern int cursor_at_eol();
+extern void swap_int(int *a, int *b);
+extern void deletech(uint8_t op);
+
+// erow definition
+struct erow {
+	char *line;
+	char *render;
+	int size;
+	int rsize;
+	int cap;
+};
+
+// editor_t definition
+struct editor_t {
+	struct termios entry_term;
+	int rows, cols;
+	int curx, cury;
+	int rx;
+	int mode;
+	int nrows;
+	int rowoffs, coloffs;
+	struct erow *row;
+	struct erow *killring;
+	int kill;
+	int no_kill;
+	char *filename;
+	int dirty;
+	int dirtyex;
+	char msg[80];
+	int mark_set;
+	int mark_curx, mark_cury;
+	time_t msgtm;
+};
+
+namespace ke {
+
+void Killring::flush(editor_t* editor) {
+    if (editor->killring != nullptr) {
+        erow_free(editor->killring);
+        free(editor->killring);
+        editor->killring = nullptr;
+    }
+}
+
+void Killring::yank(editor_t* editor) {
+    if (editor->killring == nullptr) {
+        return;
+    }
+    /*
+     * Insert killring contents at the cursor without clearing the ring.
+     * Interpret '\n' as an actual newline() rather than inserting a raw 0x0A
+     * byte, so yanked content preserves lines correctly.
+     */
+    for (int i = 0; i < editor->killring->size; i++) {
+        unsigned char ch = (unsigned char) editor->killring->line[i];
+        if (ch == '\n') {
+            newline();
+        } else {
+            insertch(ch);
+        }
+    }
+}
+
+void Killring::start_with_char(editor_t* editor, unsigned char ch) {
+    erow* row = nullptr;
+    
+    if (editor->killring != nullptr) {
+        erow_free(editor->killring);
+        free(editor->killring);
+        editor->killring = nullptr;
+    }
+    
+    editor->killring = static_cast<erow*>(malloc(sizeof(erow)));
+    assert(editor->killring != nullptr);
+    assert(erow_init(editor->killring, 0) == 0);
+    
+    /* append one char to empty killring without affecting editor.dirty */
+    row = editor->killring;
+    
+    row->line = static_cast<char*>(realloc(row->line, row->size + 2));
+    assert(row->line != nullptr);
+    row->line[row->size] = ch;
+    row->size++;
+    row->line[row->size] = '\0';
+    erow_update(row);
+}
+
+void Killring::append_char(editor_t* editor, unsigned char ch) {
+    erow* row = nullptr;
+    
+    if (editor->killring == nullptr) {
+        start_with_char(editor, ch);
+        return;
+    }
+    
+    row = editor->killring;
+    row->line = static_cast<char*>(realloc(row->line, row->size + 2));
+    assert(row->line != nullptr);
+    row->line[row->size] = ch;
+    row->size++;
+    row->line[row->size] = '\0';
+    erow_update(row);
+}
+
+void Killring::prepend_char(editor_t* editor, unsigned char ch) {
+    if (editor->killring == nullptr) {
+        start_with_char(editor, ch);
+        return;
+    }
+    
+    erow* row = editor->killring;
+    row->line = static_cast<char*>(realloc(row->line, row->size + 2));
+    assert(row->line != nullptr);
+    memmove(&row->line[1], &row->line[0], row->size + 1);
+    row->line[0] = ch;
+    row->size++;
+    erow_update(row);
+}
+
+void Killring::toggle_markset(editor_t* editor) {
+    if (editor->mark_set) {
+        editor->mark_set = 0;
+        editor_set_status("Mark cleared.");
+        return;
+    }
+    
+    editor->mark_set = 1;
+    editor->mark_curx = editor->curx;
+    editor->mark_cury = editor->cury;
+    editor_set_status("Mark set.");
+}
+
+int Killring::cursor_after_mark(editor_t* editor) {
+    if (editor->mark_cury < editor->cury) {
+        return 1;
+    }
+    
+    if (editor->mark_cury > editor->cury) {
+        return 0;
+    }
+    
+    return editor->curx >= editor->mark_curx;
+}
+
+int Killring::count_chars_from_cursor_to_mark(editor_t* editor) {
+    int count = 0;
+    int curx = editor->curx;
+    int cury = editor->cury;
+    
+    int markx = editor->mark_curx;
+    int marky = editor->mark_cury;
+    
+    if (!cursor_after_mark(editor)) {
+        swap_int(&curx, &markx);
+        swap_int(&cury, &marky);
+    }
+    
+    editor->curx = markx;
+    editor->cury = marky;
+    
+    while (editor->cury != cury) {
+        while (!cursor_at_eol()) {
+            move_cursor(1000 + 3); // ARROW_RIGHT
+            count++;
+        }
+        
+        move_cursor(1000 + 3); // ARROW_RIGHT
+        count++;
+    }
+    
+    while (editor->curx != curx) {
+        count++;
+        move_cursor(1000 + 3); // ARROW_RIGHT
+    }
+    
+    return count;
+}
+
+void Killring::kill_region(editor_t* editor) {
+    int curx = editor->curx;
+    int cury = editor->cury;
+    int markx = editor->mark_curx;
+    int marky = editor->mark_cury;
+    
+    if (!editor->mark_set) {
+        return;
+    }
+    
+    /* kill the current killring */
+    flush(editor);
+    
+    if (!cursor_after_mark(editor)) {
+        swap_int(&curx, &markx);
+        swap_int(&cury, &marky);
+    }
+    
+    editor->curx = markx;
+    editor->cury = marky;
+    
+    while (editor->cury != cury) {
+        while (!cursor_at_eol()) {
+            append_char(editor, editor->row[editor->cury].line[editor->curx]);
+            move_cursor(1000 + 3); // ARROW_RIGHT
+        }
+        append_char(editor, '\n');
+        move_cursor(1000 + 3); // ARROW_RIGHT
+    }
+    
+    while (editor->curx != curx) {
+        append_char(editor, editor->row[editor->cury].line[editor->curx]);
+        move_cursor(1000 + 3); // ARROW_RIGHT
+    }
+    
+    editor_set_status("Region killed.");
+}
+
+void Killring::delete_region(editor_t* editor) {
+    int count = count_chars_from_cursor_to_mark(editor);
+    int killed = 0;
+    int curx = editor->curx;
+    int cury = editor->cury;
+    int markx = editor->mark_curx;
+    int marky = editor->mark_cury;
+    
+    if (!editor->mark_set) {
+        return;
+    }
+    
+    if (!cursor_after_mark(editor)) {
+        swap_int(&curx, &markx);
+        swap_int(&cury, &marky);
+    }
+    
+    editor->curx = markx;
+    editor->cury = marky;
+    
+    while (killed < count) {
+        deletech(0); // KILLRING_NO_OP
+        killed++;
+    }
+    
+    editor->kill = 1;
+    editor_set_status("Region killed.");
+}
+
+} // namespace ke

killring.h

@@ -0,0 +1,44 @@
+#ifndef KILLRING_HPP
+#define KILLRING_HPP
+
+#include <cstdint>
+
+// Forward declarations
+struct editor_t;
+
+namespace ke {
+
+/**
+ * Killring class for cut/paste (kill/yank) operations.
+ */
+class Killring {
+public:
+    Killring() = default;
+    ~Killring() = default;
+    
+    // Deleted copy constructor and assignment
+    Killring(const Killring&) = delete;
+    Killring& operator=(const Killring&) = delete;
+    
+    // Killring operations
+    static void flush(editor_t* editor);
+    static void yank(editor_t* editor);
+    static void start_with_char(editor_t* editor, unsigned char ch);
+    static void append_char(editor_t* editor, unsigned char ch);
+    static void prepend_char(editor_t* editor, unsigned char ch);
+    
+    // Mark operations
+    static void toggle_markset(editor_t* editor);
+    static int cursor_after_mark(editor_t* editor);
+    
+    // Region operations
+    static void kill_region(editor_t* editor);
+    static void delete_region(editor_t* editor);
+    
+private:
+    static int count_chars_from_cursor_to_mark(editor_t* editor);
+};
+
+} // namespace ke
+
+#endif // KILLRING_HPP

terminal.cc

@@ -0,0 +1,111 @@
+#include "terminal.h"
+#include <sys/ioctl.h>
+#include <unistd.h>
+#include <cstdio>
+#include <cstdlib>
+
+namespace ke {
+
+static Terminal* g_terminal_instance = nullptr;
+
+static void cleanup_terminal_on_exit() {
+    if (g_terminal_instance) {
+        g_terminal_instance->disable_raw_mode();
+    }
+}
+
+Terminal::Terminal() : raw_mode_enabled_(false) {
+    g_terminal_instance = this;
+}
+
+Terminal::~Terminal() {
+    if (raw_mode_enabled_) {
+        disable_raw_mode();
+    }
+    g_terminal_instance = nullptr;
+}
+
+void Terminal::setup() {
+    if (tcgetattr(STDIN_FILENO, &entry_term_) == -1) {
+        perror("can't snapshot terminal settings");
+        exit(1);
+    }
+    atexit(cleanup_terminal_on_exit);
+    enable_raw_mode();
+}
+
+void Terminal::enable_raw_mode() {
+    if (raw_mode_enabled_) {
+        return;
+    }
+    
+    struct termios raw;
+    
+    /* Read the current terminal parameters for standard input. */
+    if (tcgetattr(STDIN_FILENO, &raw) == -1) {
+        perror("tcgetattr while enabling raw mode");
+        exit(1);
+    }
+    
+    /*
+     * Put the terminal into raw mode.
+     */
+    cfmakeraw(&raw);
+    
+    /*
+     * Set timeout for read(2).
+     *
+     * VMIN: what is the minimum number of bytes required for read
+     * to return?
+     *
+     * VTIME: max time before read(2) returns in hundreds of milli-
+     * seconds.
+     */
+    raw.c_cc[VMIN] = 0;
+    raw.c_cc[VTIME] = 1;
+    
+    /*
+     * Now write the terminal parameters to the current terminal,
+     * after flushing any waiting input out.
+     */
+    if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &raw) == -1) {
+        perror("tcsetattr while enabling raw mode");
+        exit(1);
+    }
+    
+    raw_mode_enabled_ = true;
+}
+
+void Terminal::disable_raw_mode() {
+    if (!raw_mode_enabled_) {
+        return;
+    }
+    
+    clear_screen();
+    
+    if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &entry_term_) == -1) {
+        perror("couldn't disable terminal raw mode");
+        exit(1);
+    }
+    
+    raw_mode_enabled_ = false;
+}
+
+int Terminal::get_window_size(int* rows, int* cols) {
+    struct winsize ws;
+    
+    if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) == -1 || ws.ws_col == 0) {
+        return -1;
+    }
+    
+    *cols = ws.ws_col;
+    *rows = ws.ws_row;
+    return 0;
+}
+
+void Terminal::clear_screen() {
+    (void)write(STDOUT_FILENO, "\x1b[2J", 4);
+    (void)write(STDOUT_FILENO, "\x1b[H", 3);
+}
+
+} // namespace ke

terminal.h

@@ -0,0 +1,39 @@
+#ifndef TERMINAL_HPP
+#define TERMINAL_HPP
+
+#include <termios.h>
+
+namespace ke {
+
+/**
+ * Terminal management class for handling raw mode and terminal operations.
+ */
+class Terminal {
+public:
+    Terminal();
+    ~Terminal();
+    
+    // Deleted copy constructor and assignment
+    Terminal(const Terminal&) = delete;
+    Terminal& operator=(const Terminal&) = delete;
+    
+    // Setup and teardown
+    void setup();
+    void enable_raw_mode();
+    void disable_raw_mode();
+    
+    // Terminal operations
+    static int get_window_size(int* rows, int* cols);
+    static void clear_screen();
+    
+    // Access to original terminal settings
+    const termios& entry_term() const { return entry_term_; }
+    
+private:
+    termios entry_term_;
+    bool raw_mode_enabled_;
+};
+
+} // namespace ke
+
+#endif // TERMINAL_HPP