Import a simple text editor I started working on.

Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/ca6847b5bb6

AK/Bitmap.h

@@ -1,6 +1,6 @@
 #pragma once
 
-#include "StdLib.h"
+#include "StdLibExtras.h"
 #include "Types.h"
 #include "kmalloc.h"
 #include "Assertions.h"

AK/Buffer.h

@@ -3,7 +3,7 @@
 #include "Assertions.h"
 #include "Retainable.h"
 #include "RetainPtr.h"
-#include "StdLib.h"
+#include "StdLibExtras.h"
 #include "kmalloc.h"
 
 namespace AK {

AK/ByteBuffer.h

@@ -2,7 +2,7 @@
 
 #include "Buffer.h"
 #include "Types.h"
-#include "StdLib.h"
+#include "StdLibExtras.h"
 
 namespace AK {
 

AK/DoublyLinkedList.h

@@ -1,6 +1,6 @@
 #pragma once
 
-#include "StdLib.h"
+#include "StdLibExtras.h"
 
 namespace AK {
 

AK/FileSystemPath.h

@@ -1,6 +1,6 @@
 #pragma once
 
-#include "String.h"
+#include "AKString.h"
 
 namespace AK {
 

AK/Function.h

@@ -27,7 +27,7 @@
 
 #include "Assertions.h"
 #include "OwnPtr.h"
-#include "StdLib.h"
+#include "StdLibExtras.h"
 
 namespace AK {
 

AK/HashMap.h

@@ -1,7 +1,7 @@
 #pragma once
 
 #include "HashTable.h"
-#include "StdLib.h"
+#include "StdLibExtras.h"
 #include "kstdio.h"
 
 namespace AK {

AK/HashTable.h

@@ -3,7 +3,7 @@
 #include "Assertions.h"
 #include "DoublyLinkedList.h"
 #include "Traits.h"
-#include "StdLib.h"
+#include "StdLibExtras.h"
 #include "kstdio.h"
 
 //#define HASHTABLE_DEBUG

AK/Makefile

@@ -5,7 +5,7 @@ CXXFLAGS = -std=c++17 -O0 -W -Wall -ggdb3
 
 all:	$(PROGRAM)
 
-test.o: Vector.h String.h StringImpl.h MappedFile.h HashTable.h SinglyLinkedList.h Traits.h HashMap.h TemporaryFile.h Buffer.h FileSystemPath.h StringBuilder.h
+test.o: Vector.h AKString.h StringImpl.h MappedFile.h HashTable.h SinglyLinkedList.h Traits.h HashMap.h TemporaryFile.h Buffer.h FileSystemPath.h StringBuilder.h
 
 .cpp.o:
 	$(CXX) $(CXXFLAGS) -o $@ -c $<

AK/MappedFile.h

@@ -1,6 +1,6 @@
 #pragma once
 
-#include "String.h"
+#include "AKString.h"
 
 namespace AK {
 

AK/Noncopyable.h

@@ -0,0 +1,6 @@
+#pragma once
+
+#define AK_MAKE_NONCOPYABLE(c) \
+private: \
+    c(const c&) = delete; \
+    c& operator=(const c&) = delete;

AK/OwnPtr.h

@@ -1,6 +1,6 @@
 #pragma once
 
-#include "StdLib.h"
+#include "StdLibExtras.h"
 #include "Types.h"
 #include "Traits.h"
 

AK/String.cpp

@@ -1,5 +1,5 @@
-#include "String.h"
+#include "AKString.h"
-#include "StdLib.h"
+#include "StdLibExtras.h"
 
 namespace AK {
 

AK/StringBuilder.h

@@ -1,6 +1,6 @@
 #pragma once
 
-#include "String.h"
+#include "AKString.h"
 #include "Vector.h"
 
 namespace AK {

AK/StringImpl.cpp

@@ -1,5 +1,5 @@
 #include "StringImpl.h"
-#include "StdLib.h"
+#include "StdLibExtras.h"
 #include "kmalloc.h"
 
 namespace AK {

AK/TemporaryFile.h

@@ -1,6 +1,6 @@
 #pragma once
 
-#include "String.h"
+#include "AKString.h"
 #include <stdio.h>
 
 namespace AK {

AK/test.cpp

@@ -1,4 +1,4 @@
-#include "String.h"
+#include "AKString.h"
 //#include "StringBuilder.h"
 #include "Vector.h"
 #include <stdio.h>

Editor/Document.cpp

@@ -0,0 +1,46 @@
+#include "Document.h"
+#include "FileReader.h"
+
+OwnPtr<Document> Document::create_from_file(const std::string& path)
+{
+    auto document = make<Document>();
+
+    FileReader reader(path);
+    while (reader.can_read()) {
+        auto line = reader.read_line();
+        document->m_lines.push_back(Line(line));
+    }
+
+    return document;
+}
+
+void Document::dump()
+{
+    fprintf(stderr, "Document{%p}\n", this);
+    for (size_t i = 0; i < m_lines.size(); ++i) {
+        fprintf(stderr, "[%02zu] %s\n", i, m_lines[i].data().c_str());
+    }
+}
+
+bool Document::backspace_at(Position position)
+{
+    return false;
+}
+
+bool Document::insert_at(Position position, const std::string& text)
+{
+    static FILE* f = fopen("log", "a");
+    fprintf(f, "@%zu,%zu: +%s\n", position.line(), position.column(), text.c_str());
+    fflush(f);
+    ASSERT(position.is_valid());
+    if (!position.is_valid())
+        return false;
+    ASSERT(position.line() < line_count());
+    if (position.line() >= line_count())
+        return false;
+    Line& line = m_lines[position.line()];
+    if (position.column() > line.length())
+        return false;
+    line.insert(position.column(), text);
+    return true;
+}

Editor/Document.h

@@ -0,0 +1,27 @@
+#pragma once
+
+#include "cuki.h"
+#include "Line.h"
+#include "Position.h"
+#include "OwnPtr.h"
+#include <string>
+
+class Document {
+public:
+    Document() { }
+    ~Document() { }
+
+    const std::deque<Line>& lines() const { return m_lines; }
+    std::deque<Line>& lines() { return m_lines; }
+    size_t line_count() const { return m_lines.size(); }
+
+    static OwnPtr<Document> create_from_file(const std::string& path);
+
+    bool insert_at(Position, const std::string&);
+    bool backspace_at(Position);
+
+    void dump();
+
+private:
+    std::deque<Line> m_lines;
+};

Editor/Editor.cpp

@@ -0,0 +1,336 @@
+#include "Editor.h"
+#include "Document.h"
+#include "InsertOperation.h"
+
+#define _XOPEN_SOURCE_EXTENDED
+#include <locale.h>
+#include <ncurses.h>
+
+static int statusbar_attributes;
+static int ruler_attributes;
+
+Editor::Editor()
+{
+    setlocale(LC_ALL, "");
+    initscr();
+    start_color();
+    use_default_colors();
+
+    init_pair(1, COLOR_WHITE, COLOR_BLUE);
+    init_pair(2, COLOR_BLUE, -1);
+
+    statusbar_attributes = COLOR_PAIR(1);
+    ruler_attributes = COLOR_PAIR(2);
+
+    raw();
+    keypad(stdscr, true);
+    timeout(10);
+    noecho();
+    refresh();
+}
+
+Editor::~Editor()
+{
+    //move(2, 2);
+    //printw("*** Press any key to exit! ***");
+    //getch();
+    endwin();
+}
+
+void Editor::set_document(OwnPtr<Document>&& document)
+{
+    m_document = std::move(document);
+    m_cursor.move_to(0, 0);
+    m_scroll_position.move_to(0, 0);
+}
+
+void Editor::redraw()
+{
+    clear();
+    if (!m_document)
+        return;
+
+    size_t window_height = getmaxy(stdscr);
+    size_t window_width = getmaxx(stdscr);
+
+    for (size_t row = 0; row < window_height - 1; ++row) {
+        size_t current_document_line = m_scroll_position.line() + row;
+        size_t current_document_column = m_scroll_position.column();
+
+        move(row, 0);
+
+        if (current_document_line >= m_document->line_count()) {
+            printw("~");
+        } else {
+            attron(ruler_attributes);
+            printw("%3d ", current_document_line);
+            attroff(ruler_attributes);
+            m_ruler_width = 4;
+            size_t line_length = m_document->lines()[current_document_line].data().size();
+            const char* line_data = m_document->lines()[current_document_line].data().c_str();
+            if (m_scroll_position.column() < line_length)
+                addnstr(line_data + m_scroll_position.column(), window_width - m_ruler_width);
+        }
+    }
+
+    draw_status_bar();
+
+    draw_cursor();
+    refresh();
+}
+
+void Editor::draw_cursor()
+{
+    ssize_t cursor_row_on_screen = m_cursor.line() - m_scroll_position.line();
+    ssize_t cursor_column_on_screen = m_cursor.column() - m_scroll_position.column();
+
+    move(cursor_row_on_screen, cursor_column_on_screen + m_ruler_width);
+
+}
+
+void Editor::draw_status_bar()
+{
+    int old_background = getbkgd(stdscr);
+    bkgdset(' ' | statusbar_attributes);
+    
+    size_t window_height = getmaxy(stdscr);
+    size_t window_width = getmaxx(stdscr);
+
+    move(window_height - 1, 0);
+    clrtoeol();
+
+    if (is_editing_document()) {
+        attron(A_STANDOUT);
+        printw("* Editing *");
+        attroff(A_STANDOUT);
+    } else if (is_editing_command()) {
+        printw("\\%s", m_command.c_str());
+    } else {
+        attron(A_BOLD);
+        addstr("~(^_^)~ ");
+        if (m_status_text.size() > 0) {
+            addstr(m_status_text.c_str());
+        }
+        attroff(A_BOLD);
+    }
+
+    move(window_height - 1, window_width - 20);
+    printw("%zu, %zu", m_scroll_position.line(), m_scroll_position.column());
+
+    move(window_height - 1, window_width - 8);
+    printw("%zu, %zu", m_cursor.line(), m_cursor.column());
+    attroff(statusbar_attributes);
+
+    bkgdset(old_background);
+}
+
+int Editor::exec()
+{
+    while (!m_should_quit) {
+        redraw();
+        int ch = getch();
+        if (ch == ERR) {
+            continue;
+            fprintf(stderr, "getch() returned ERR\n");
+            break;
+        }
+
+        if (is_editing_document() || is_editing_command()) {
+            if (ch == 27)
+                set_mode(Idle);
+            else {
+                if (is_editing_document())
+                    handle_document_key_press(ch);
+                else
+                    handle_command_key_press(ch);
+            }
+        } else {
+            switch (ch) {
+            case 'h': move_left(); break;
+            case 'j': move_down(); break;
+            case 'k': move_up(); break;
+            case 'l': move_right(); break;
+            case 'i': set_mode(EditingDocument); break;
+            case 'q': m_should_quit = true; break;
+            case '\\': set_mode(EditingCommand); break;
+            }
+        }
+    }
+    return 0;
+}
+
+void Editor::move_left()
+{
+    if (m_cursor.column() == 0)
+        return;
+    m_cursor.move_by(0, -1);
+    update_scroll_position_if_needed();
+}
+
+void Editor::move_down()
+{
+    if (m_cursor.line() >= max_line())
+        return;
+    m_cursor.move_by(1, 0);
+    if (m_cursor.column() > max_column())
+        m_cursor.set_column(max_column());
+
+    update_scroll_position_if_needed();
+}
+
+void Editor::move_up()
+{
+    if (m_cursor.line() == 0)
+        return;
+    m_cursor.move_by(-1, 0);
+    if (m_cursor.column() > max_column())
+        m_cursor.set_column(max_column());
+
+    update_scroll_position_if_needed();
+}
+
+void Editor::move_right()
+{
+    if (m_cursor.column() >= max_column())
+        return;
+    m_cursor.move_by(0, 1);
+    update_scroll_position_if_needed();
+}
+
+size_t Editor::max_line() const
+{
+    return m_document->line_count() - 1;
+}
+
+size_t Editor::max_column() const
+{
+    return m_document->lines()[m_cursor.line()].data().size();
+}
+
+void Editor::update_scroll_position_if_needed()
+{
+    ssize_t max_row = getmaxy(stdscr) - 2;
+    ssize_t max_column = getmaxx(stdscr) - 1 - m_ruler_width;
+
+    ssize_t cursor_row_on_screen = m_cursor.line() - m_scroll_position.line();
+    ssize_t cursor_column_on_screen = m_cursor.column() - m_scroll_position.column();
+
+    // FIXME: Need to move by more than just 1 step sometimes!
+
+    if (cursor_row_on_screen < 0) {
+        m_scroll_position.move_by(-1, 0);
+    }
+    
+    if (cursor_row_on_screen > max_row) {
+        m_scroll_position.move_by(1, 0);
+    }
+
+    if (cursor_column_on_screen < 0) {
+        m_scroll_position.move_by(0, -1);
+    }
+
+    if (cursor_column_on_screen > max_column) {
+        m_scroll_position.move_by(0, 1);
+    }
+}
+
+void Editor::set_mode(Mode m)
+{
+    if (m_mode == m)
+        return;
+    m_mode = m;
+    m_command = "";
+}
+
+static bool is_backspace(int ch)
+{
+    return ch == 8 || ch == 127;
+}
+
+static bool is_newline(int ch)
+{
+    return ch == 10 || ch == 13;
+}
+
+void Editor::handle_command_key_press(int ch)
+{
+    if (is_backspace(ch)) {
+        if (m_command.size() > 0)
+            m_command.pop_back();
+        else
+            set_mode(Idle);
+        return;
+    }
+    if (is_newline(ch)) {
+        if (m_command.size() > 0)
+            exec_command();
+        set_mode(Idle);
+        return;
+    }
+    m_command.push_back(ch);
+}
+
+void Editor::handle_document_key_press(int ch)
+{
+    if (is_backspace(ch)) {
+        //auto op = make<EraseOperation>(1);
+        m_document->backspace_at(m_cursor);
+    } else {
+        auto op = make<InsertOperation>(ch);
+        run(std::move(op));
+    }
+}
+
+void Editor::run(OwnPtr<Operation>&& op)
+{
+    ASSERT(op);
+    op->apply(*this);
+    m_undo_stack.push(std::move(op));
+}
+
+void Editor::insert_at_cursor(int ch)
+{
+    std::string s;
+    s += ch;
+    m_document->insert_at(m_cursor, s);
+    m_cursor.move_by(0, 1);
+}
+
+bool Editor::insert_text_at_cursor(const std::string& text)
+{
+    ASSERT(text.size() == 1);
+    m_document->insert_at(m_cursor, text);
+    m_cursor.move_by(0, text.size());
+    return true;
+}
+
+bool Editor::remove_text_at_cursor(const std::string& text)
+{
+    // FIXME: Implement
+    ASSERT(false);
+    return false;
+}
+
+void Editor::set_status_text(const std::string& text)
+{
+    m_status_text = text;
+}
+
+void Editor::exec_command()
+{
+    if (m_command == "q") {
+        m_should_quit = true;
+        return;
+    }
+
+    if (m_command == "about") {
+        set_status_text("cuki editor!");
+        return;
+    }
+
+    std::string s;
+    s = "Invalid command: '";
+    s += m_command;
+    s += "'";
+    set_status_text(s);
+}

Editor/Editor.h

@@ -0,0 +1,74 @@
+#pragma once
+
+#include "OwnPtr.h"
+#include "Position.h"
+#include "UndoStack.h"
+#include <string>
+
+class Document;
+
+class Editor {
+public:
+    Editor();
+    ~Editor();
+
+    void set_document(OwnPtr<Document>&&);
+    void redraw();
+
+    int exec();
+
+    enum Mode {
+        Idle,
+        EditingCommand,
+        EditingDocument,
+    };
+
+    void set_mode(Mode);
+    Mode mode() const { return m_mode; } 
+    bool is_editing_document() const { return m_mode == EditingDocument; }
+    bool is_editing_command() const { return m_mode == EditingCommand; }
+    bool is_idle() const { return m_mode == Idle; }
+
+    void set_status_text(const std::string&);
+
+    bool insert_text_at_cursor(const std::string&);
+    bool remove_text_at_cursor(const std::string&);
+
+    void run(OwnPtr<Operation>&&);
+
+private:
+    void move_left();
+    void move_down();
+    void move_up();
+    void move_right();
+
+    size_t max_line() const;
+    size_t max_column() const;
+
+    void update_scroll_position_if_needed();
+
+    void draw_status_bar();
+    void draw_cursor();
+
+    void handle_document_key_press(int ch);
+    void handle_command_key_press(int ch);
+
+    void insert_at_cursor(int ch);
+
+    void exec_command();
+
+    OwnPtr<Document> m_document;
+
+    UndoStack m_undo_stack;
+
+    // Document relative
+    Position m_scroll_position;
+    Position m_cursor;
+
+    std::string m_command;
+    std::string m_status_text;
+
+    bool m_should_quit { false };
+    size_t m_ruler_width { 0 };
+    Mode m_mode { Idle };
+};

Editor/FileReader.cpp

@@ -0,0 +1,40 @@
+#include "FileReader.h"
+
+FileReader::FileReader(const std::string& path)
+    : m_path(path)
+{
+    m_file = fopen(path.c_str(), "r");
+}
+
+FileReader::~FileReader()
+{
+    if (m_file)
+        fclose(m_file);
+    m_file = nullptr;
+}
+
+bool FileReader::can_read() const
+{
+    return m_file && !feof(m_file);
+}
+
+std::string FileReader::read_line()
+{
+    if (!m_file) {
+        fprintf(stderr, "Error: FileReader::readLine() called on invalid FileReader for '%s'\n", m_path.c_str());
+        return std::string();
+    }
+
+    std::string line;
+
+    while (can_read()) {
+        int ch = fgetc(m_file);
+        if (ch == EOF)
+            break;
+        if (ch == '\n')
+            break;
+        line += ch;
+    }
+
+    return line;
+}

Editor/FileReader.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <string>
+#include <stdio.h>
+
+class FileReader {
+public:
+    explicit FileReader(const std::string& path);
+    ~FileReader();
+
+    bool can_read() const;
+    std::string read_line();
+
+private:
+    std::string m_path;
+    FILE* m_file { nullptr };
+};

Editor/InsertOperation.cpp

@@ -0,0 +1,26 @@
+#include "InsertOperation.h"
+#include "Editor.h"
+
+InsertOperation::InsertOperation(const std::string& text)
+    : m_text(text)
+{
+}
+
+InsertOperation::InsertOperation(char ch)
+    : m_text(&ch, 1)
+{
+}
+
+InsertOperation::~InsertOperation()
+{
+}
+
+bool InsertOperation::apply(Editor& editor)
+{
+    return editor.insert_text_at_cursor(m_text);
+}
+
+bool InsertOperation::unapply(Editor& editor)
+{
+    return editor.remove_text_at_cursor(m_text);
+}

Editor/InsertOperation.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include "Operation.h"
+#include <string>
+
+class InsertOperation final : public Operation {
+public:
+    explicit InsertOperation(const std::string&);
+    explicit InsertOperation(char);
+    ~InsertOperation();
+
+    virtual bool apply(Editor&) override;
+    virtual bool unapply(Editor&) override;
+
+private:
+    std::string m_text;
+};

Editor/Line.cpp

@@ -0,0 +1,95 @@
+#include "Line.h"
+
+Chunk::Chunk(const std::string& str)
+    : m_data(str)
+{
+}
+
+Chunk::~Chunk()
+{
+}
+
+Line::Line(const std::string& str)
+{
+    m_chunks.push_back(Chunk(str));
+}
+
+Line::Line(Line&& other)
+    : m_chunks(std::move(other.m_chunks))
+{
+}
+
+Line::~Line()
+{
+}
+
+std::string Line::data() const
+{
+    std::string str;
+    for (auto& chunk : m_chunks)
+        str += chunk.data();
+    return str;
+}
+
+void Line::append(const std::string& text)
+{
+    m_chunks.push_back(Chunk(text));
+}
+
+void Line::prepend(const std::string& text)
+{
+    m_chunks.push_front(Chunk(text));
+}
+
+void Line::insert(size_t index, const std::string& text)
+{
+    if (index == 0) {
+        prepend(text);
+        return;
+    }
+
+    if (index == length()) {
+        append(text);
+        return;
+    }
+
+    auto chunkAddress = chunkIndexForPosition(index);
+    auto chunkIndex = std::get<0>(chunkAddress);
+    auto& chunk = m_chunks[chunkIndex];
+    auto indexInChunk = std::get<1>(chunkAddress);
+
+    static FILE* f = fopen("log", "a");
+    fprintf(f, "#Column:%zu, Chunk:%zu, Index:%zu\n", index, chunkIndex, indexInChunk);
+    
+    auto leftString = chunk.data().substr(0, indexInChunk);
+    auto rightString = chunk.data().substr(indexInChunk, chunk.length() - indexInChunk);
+
+    fprintf(f, "#{\"%s\", \"%s\", \"%s\"}\n", leftString.c_str(), text.c_str(), rightString.c_str());
+    fflush(f);
+
+    Chunk leftChunk { leftString };
+    Chunk midChunk { text };
+    Chunk rightChunk { rightString };
+
+    auto iterator = m_chunks.begin() + chunkIndex;
+    m_chunks.erase(iterator);
+    iterator = m_chunks.begin() + chunkIndex;
+
+    // Note reverse insertion order!
+    m_chunks.insert(iterator, rightChunk);
+    m_chunks.insert(iterator, midChunk);
+    m_chunks.insert(iterator, leftChunk);
+}
+
+std::tuple<size_t, size_t> Line::chunkIndexForPosition(size_t position)
+{
+    ASSERT(position < length());
+    size_t seen { 0 };
+    for (size_t i = 0; i < m_chunks.size(); ++i) {
+        if (position < seen + m_chunks[i].length())
+            return std::make_tuple(i, position - seen);
+        seen += m_chunks[i].length();
+    }
+    ASSERT(false);
+    return std::make_tuple(0, 0);
+}

Editor/Line.h

@@ -0,0 +1,40 @@
+#pragma once
+
+#include "cuki.h"
+#include <deque>
+#include <string>
+#include <tuple>
+
+class Chunk {
+public:
+    explicit Chunk(const std::string&);
+    ~Chunk();
+
+    const std::string& data() const { return m_data; }
+    size_t length() const { return m_data.size(); }
+
+private:
+    std::string m_data;
+};
+
+class Line {
+    AK_MAKE_NONCOPYABLE(Line);
+public:
+    Line() { }
+    Line(const std::string&);
+    Line(Line&&);
+    ~Line();
+
+    std::string data() const;
+    size_t length() const { return data().size(); }
+
+    void insert(size_t index, const std::string&);
+
+private:
+    void append(const std::string&);
+    void prepend(const std::string&);
+
+    std::tuple<size_t, size_t> chunkIndexForPosition(size_t);
+
+    std::deque<Chunk> m_chunks;
+};

Editor/Makefile

@@ -0,0 +1,25 @@
+BINARY = cuki
+
+OBJS = \
+	Document.o \
+	Line.o \
+	FileReader.o \
+	Editor.o \
+	main.o \
+        InsertOperation.o \
+        Operation.o \
+        UndoStack.o
+
+CXXFLAGS = -Os -std=c++1z -W -Wall -g -I../AK
+LDFLAGS = -lncurses
+
+$(BINARY): $(OBJS)
+	$(CXX) $(LDFLAGS) -o $@ $(OBJS)
+
+all: $(BINARY)
+
+clean:
+	rm -f $(BINARY) $(OBJS)
+
+%.o: %.cpp
+	$(CXX) $(CXXFLAGS) -c $< -o $@

Editor/Operation.cpp

@@ -0,0 +1,9 @@
+#include "Operation.h"
+
+Operation::Operation()
+{
+}
+
+Operation::~Operation()
+{
+}

Editor/Operation.h

@@ -0,0 +1,14 @@
+#pragma once
+
+class Editor;
+
+class Operation {
+public:
+    virtual ~Operation();
+
+    virtual bool apply(Editor&) = 0;
+    virtual bool unapply(Editor&) = 0;
+
+protected:
+    Operation();
+};

Editor/Position.h

@@ -0,0 +1,27 @@
+#pragma once
+
+#include <unistd.h>
+
+class Position {
+public:
+    Position() { }
+    Position(size_t line, size_t column) : m_line(line), m_column(column) { }
+
+    size_t line() const { return m_line; }
+    size_t column() const { return m_column; }
+
+    void set_line(size_t l) { m_line = l; }
+    void set_column(size_t c) { m_column = c; }
+
+    void move_to(size_t l, size_t c) { m_line = l; m_column = c; }
+
+    void move_by(ssize_t l, ssize_t c) { m_line += l; m_column += c; }
+
+    bool is_valid() const { return m_line != InvalidValue && m_column != InvalidValue; }
+
+private:
+    static const size_t InvalidValue = 0xFFFFFFFF;
+
+    size_t m_line { InvalidValue };
+    size_t m_column { InvalidValue };
+};

Editor/UndoStack.cpp

@@ -0,0 +1,14 @@
+#include "cuki.h"
+#include "UndoStack.h"
+
+void UndoStack::push(OwnPtr<Operation>&& op)
+{
+    m_stack.push(std::move(op));
+}
+
+OwnPtr<Operation> UndoStack::pop()
+{
+    OwnPtr<Operation> op = std::move(m_stack.top());
+    m_stack.pop();
+    return op;
+}

Editor/UndoStack.h

@@ -0,0 +1,18 @@
+#pragma once
+
+#include <stack>
+#include "Operation.h"
+#include "OwnPtr.h"
+
+class UndoStack {
+public:
+    UndoStack() { }
+
+    void push(OwnPtr<Operation>&&);
+    OwnPtr<Operation> pop();
+
+    bool is_empty() const { return m_stack.empty(); }
+
+private:
+    std::stack<OwnPtr<Operation>> m_stack;
+};

Editor/cuki.h

@@ -0,0 +1,6 @@
+// cuki text editor
+
+#include "Assertions.h"
+#include "Noncopyable.h"
+
+// eof

Editor/main.cpp

@@ -0,0 +1,19 @@
+#include "Document.h"
+#include "Editor.h"
+#include <stdio.h>
+
+int main(int c, char** v)
+{
+    std::string file_to_open = "cuki.h";
+    if (c > 1) {
+        file_to_open = v[1];
+    }
+    auto document = Document::create_from_file(file_to_open);
+    if (!document) {
+        fprintf(stderr, "Failed to open file.\n");
+        return 1;
+    }
+    Editor editor;
+    editor.set_document(std::move(document));
+    return editor.exec();
+}

Kernel/ELFImage.h

@@ -2,7 +2,7 @@
 
 #include <AK/OwnPtr.h>
 #include <AK/HashMap.h>
-#include <AK/String.h>
+#include <AK/AKString.h>
 #include "elf.h"
 #include "types.h"
 

Kernel/FIFO.cpp

@@ -1,5 +1,5 @@
 #include "FIFO.h"
-#include <AK/StdLib.h>
+#include <AK/StdLibExtras.h>
 
 //#define FIFO_DEBUG
 

Kernel/MemoryManager.h

@@ -8,7 +8,7 @@
 #include <AK/RetainPtr.h>
 #include <AK/Vector.h>
 #include <AK/HashTable.h>
-#include <AK/String.h>
+#include <AK/AKString.h>
 #include <VirtualFileSystem/VirtualFileSystem.h>
 
 class Process;

Kernel/Process.cpp

@@ -12,7 +12,7 @@
 #include "i8253.h"
 #include "RTC.h"
 #include "ProcFileSystem.h"
-#include <AK/StdLib.h>
+#include <AK/StdLibExtras.h>
 #include <LibC/signal_numbers.h>
 #include "Syscall.h"
 #include "Scheduler.h"

Kernel/Process.h

@@ -8,7 +8,7 @@
 #include <VirtualFileSystem/VirtualFileSystem.h>
 #include <VirtualFileSystem/UnixTypes.h>
 #include <AK/InlineLinkedList.h>
-#include <AK/String.h>
+#include <AK/AKString.h>
 #include <AK/Vector.h>
 
 class FileDescriptor;

Kernel/VirtualConsole.cpp

@@ -4,7 +4,7 @@
 #include "IO.h"
 #include "StdLib.h"
 #include "Keyboard.h"
-#include <AK/String.h>
+#include <AK/AKString.h>
 
 static byte* s_vga_buffer;
 static VirtualConsole* s_consoles[6];

Kernel/system.h

@@ -2,7 +2,7 @@
 
 #include "types.h"
 #include <AK/Vector.h>
-#include <AK/String.h>
+#include <AK/AKString.h>
 
 struct KSym {
     dword address;

LibC/grp.cpp

@@ -3,7 +3,7 @@
 #include <stdlib.h>
 #include <unistd.h>
 #include <sys/mman.h>
-#include <AK/String.h>
+#include <AK/AKString.h>
 
 extern "C" {
 

LibC/pwd.cpp

@@ -3,7 +3,7 @@
 #include <stdlib.h>
 #include <unistd.h>
 #include <sys/mman.h>
-#include <AK/String.h>
+#include <AK/AKString.h>
 
 extern "C" {
 

LibC/termcap.cpp

@@ -3,7 +3,7 @@
 #include <string.h>
 #include <stdio.h>
 #include <AK/HashMap.h>
-#include <AK/String.h>
+#include <AK/AKString.h>
 
 //#define TERMCAP_DEBUG
 

Userland/kill.cpp

@@ -2,7 +2,7 @@
 #include <stdio.h>
 #include <signal.h>
 #include <stdlib.h>
-#include <AK/String.h>
+#include <AK/AKString.h>
 
 static unsigned parseUInt(const String& str, bool& ok)
 {

Userland/ls.cpp

@@ -5,7 +5,7 @@
 #include <string.h>
 #include <getopt.h>
 #include <sys/ioctl.h>
-#include <AK/String.h>
+#include <AK/AKString.h>
 #include <AK/Vector.h>
 
 static int do_dir(const char* path);

Userland/sleep.cpp

@@ -1,7 +1,7 @@
 #include <unistd.h>
 #include <stdio.h>
 #include <signal.h>
-#include <AK/String.h>
+#include <AK/AKString.h>
 
 static unsigned parseUInt(const String& str, bool& ok)
 {

VirtualFileSystem/Ext2FileSystem.cpp

@@ -2,7 +2,7 @@
 #include "ext2_fs.h"
 #include "UnixTypes.h"
 #include <AK/Bitmap.h>
-#include <AK/StdLib.h>
+#include <AK/StdLibExtras.h>
 #include <AK/kmalloc.h>
 #include <AK/ktime.h>
 #include <AK/kstdio.h>

VirtualFileSystem/FileBackedDiskDevice.h

@@ -2,7 +2,7 @@
 
 #include "DiskDevice.h"
 #include <AK/RetainPtr.h>
-#include <AK/String.h>
+#include <AK/AKString.h>
 #include <AK/Types.h>
 #include <stdio.h>
 

VirtualFileSystem/FileSystem.h

@@ -10,7 +10,7 @@
 #include <AK/OwnPtr.h>
 #include <AK/Retainable.h>
 #include <AK/RetainPtr.h>
-#include <AK/String.h>
+#include <AK/AKString.h>
 #include <AK/Function.h>
 #include <AK/kstdio.h>
 

VirtualFileSystem/FullDevice.cpp

@@ -1,7 +1,7 @@
 #include "FullDevice.h"
 #include "Limits.h"
 #include <LibC/errno_numbers.h>
-#include <AK/StdLib.h>
+#include <AK/StdLibExtras.h>
 #include <AK/kstdio.h>
 
 FullDevice::FullDevice()

VirtualFileSystem/NullDevice.cpp

@@ -1,6 +1,6 @@
 #include "NullDevice.h"
 #include "Limits.h"
-#include <AK/StdLib.h>
+#include <AK/StdLibExtras.h>
 #include <AK/kstdio.h>
 
 NullDevice::NullDevice()

VirtualFileSystem/RandomDevice.cpp

@@ -1,6 +1,6 @@
 #include "RandomDevice.h"
 #include "Limits.h"
-#include <AK/StdLib.h>
+#include <AK/StdLibExtras.h>
 
 RandomDevice::RandomDevice()
     : CharacterDevice(1, 8)

VirtualFileSystem/SyntheticFileSystem.cpp

@@ -1,7 +1,7 @@
 #include "SyntheticFileSystem.h"
 #include "FileDescriptor.h"
 #include <LibC/errno_numbers.h>
-#include <AK/StdLib.h>
+#include <AK/StdLibExtras.h>
 
 #ifndef SERENITY
 typedef int InterruptDisabler;

VirtualFileSystem/VirtualFileSystem.h

@@ -3,7 +3,7 @@
 #include <AK/HashMap.h>
 #include <AK/OwnPtr.h>
 #include <AK/RetainPtr.h>
-#include <AK/String.h>
+#include <AK/AKString.h>
 #include <AK/Vector.h>
 #include <AK/Function.h>
 #include "InodeIdentifier.h"

VirtualFileSystem/ZeroDevice.cpp

@@ -1,6 +1,6 @@
 #include "ZeroDevice.h"
 #include "Limits.h"
-#include <AK/StdLib.h>
+#include <AK/StdLibExtras.h>
 #include <AK/kstdio.h>
 
 ZeroDevice::ZeroDevice()