diff --git a/src/assert.cc b/src/assert.cc
index c0b782a1..40e9f6b3 100644
--- a/src/assert.cc
+++ b/src/assert.cc
@@ -3,12 +3,12 @@
 namespace Kakoune
 {
 
-assert_failed::assert_failed(const std::string& message)
+assert_failed::assert_failed(const String& message)
 {
     m_message = message;
 }
 
-std::string assert_failed::description() const
+String assert_failed::description() const
 {
     return m_message;
 }
diff --git a/src/assert.hh b/src/assert.hh
index a2b8cb7b..ceee28f2 100644
--- a/src/assert.hh
+++ b/src/assert.hh
@@ -8,11 +8,11 @@ namespace Kakoune
 
 struct assert_failed : logic_error
 {
-    assert_failed(const std::string& message);
-    std::string description() const;
+    assert_failed(const String& message);
+    String description() const;
 
 private:
-    std::string m_message;
+    String m_message;
 };
 
 }
diff --git a/src/buffer.cc b/src/buffer.cc
index f046ede9..597c2981 100644
--- a/src/buffer.cc
+++ b/src/buffer.cc
@@ -22,7 +22,7 @@ T clamp(T min, T max, T val)
     return val;
 }
 
-Buffer::Buffer(const std::string& name, Type type,
+Buffer::Buffer(const String& name, Type type,
                const String& initial_content)
     : m_name(name), m_type(type),
       m_history(1), m_history_cursor(m_history.begin()),
@@ -301,10 +301,10 @@ void Buffer::apply_modification(const Modification& modification)
     }
     case Modification::Erase:
     {
-        size_t size = modification.content.size();
-        assert(string(modification.position, modification.position + size)
+        size_t count = modification.content.length();
+        assert(string(modification.position, modification.position + count)
                == modification.content);
-        erase(modification.position, size);
+        erase(modification.position, count);
         break;
     }
     default:
diff --git a/src/buffer.hh b/src/buffer.hh
index 4f92edf1..71d7b2ac 100644
--- a/src/buffer.hh
+++ b/src/buffer.hh
@@ -1,13 +1,13 @@
 #ifndef buffer_hh_INCLUDED
 #define buffer_hh_INCLUDED
 
-#include <string>
 #include <vector>
 #include <list>
 #include <memory>
 
 #include "line_and_column.hh"
 #include "option_manager.hh"
+#include "string.hh"
 
 namespace Kakoune
 {
@@ -16,10 +16,8 @@ class Buffer;
 class Modification;
 class Window;
 
-typedef int      BufferPos;
-typedef int      BufferSize;
-typedef char     BufferChar;
-typedef std::basic_string<BufferChar> String;
+typedef int       BufferPos;
+typedef int       BufferSize;
 
 struct BufferCoord : LineAndColumn<BufferCoord>
 {
@@ -35,7 +33,7 @@ struct BufferCoord : LineAndColumn<BufferCoord>
 class BufferIterator
 {
 public:
-    typedef BufferChar value_type;
+    typedef Character  value_type;
     typedef BufferSize difference_type;
     typedef const value_type* pointer;
     typedef const value_type& reference;
@@ -52,7 +50,7 @@ public:
     bool operator>  (const BufferIterator& iterator) const;
     bool operator>= (const BufferIterator& iterator) const;
 
-    BufferChar operator* () const;
+    Character  operator* () const;
     BufferSize operator- (const BufferIterator& iterator) const;
 
     BufferIterator operator+ (BufferSize size) const;
@@ -117,7 +115,7 @@ public:
         Scratch
     };
 
-    Buffer(const std::string& name, Type type,
+    Buffer(const String& name, Type type,
            const String& initial_content = "\n");
     Buffer(const Buffer&) = delete;
     Buffer(Buffer&&) = delete;
@@ -146,7 +144,7 @@ public:
     // returns nearest valid coordinates from given ones
     BufferCoord    clamp(const BufferCoord& line_and_column) const;
 
-    const std::string& name() const { return m_name; }
+    const String& name() const { return m_name; }
 
     Window* get_or_create_window();
     void delete_window(Window* window);
@@ -191,7 +189,7 @@ private:
     BufferPos line_at(const BufferIterator& iterator) const;
     BufferSize line_length(BufferPos line) const;
 
-    std::string  m_name;
+    String  m_name;
     const Type   m_type;
 
     typedef std::vector<Modification> UndoGroup;
diff --git a/src/buffer_iterator.inl.hh b/src/buffer_iterator.inl.hh
index 5260d3ed..65ed3c04 100644
--- a/src/buffer_iterator.inl.hh
+++ b/src/buffer_iterator.inl.hh
@@ -110,7 +110,7 @@ inline void BufferIterator::on_erase(const BufferCoord& begin,
 }
 
 
-inline BufferChar BufferIterator::operator*() const
+inline Character BufferIterator::operator*() const
 {
     assert(m_buffer);
     return m_buffer->m_lines[line()].content[column()];
diff --git a/src/buffer_manager.cc b/src/buffer_manager.cc
index d8f71861..e19c889c 100644
--- a/src/buffer_manager.cc
+++ b/src/buffer_manager.cc
@@ -12,7 +12,7 @@ struct name_not_unique : logic_error {};
 void BufferManager::register_buffer(Buffer* buffer)
 {
     assert(buffer);
-    const std::string& name = buffer->name();
+    const String& name = buffer->name();
     if (m_buffers.find(name) != m_buffers.end())
         throw name_not_unique();
 
@@ -30,7 +30,7 @@ void BufferManager::unregister_buffer(Buffer* buffer)
     }
 }
 
-Buffer* BufferManager::get_buffer(const std::string& name)
+Buffer* BufferManager::get_buffer(const String& name)
 {
     if (m_buffers.find(name) == m_buffers.end())
         return nullptr;
@@ -38,10 +38,10 @@ Buffer* BufferManager::get_buffer(const std::string& name)
     return m_buffers[name];
 }
 
-CandidateList BufferManager::complete_buffername(const std::string& prefix,
+CandidateList BufferManager::complete_buffername(const String& prefix,
                                                  size_t cursor_pos)
 {
-    std::string real_prefix = prefix.substr(0, cursor_pos);
+    String real_prefix = prefix.substr(0, cursor_pos);
     CandidateList result;
     for (auto& buffer : m_buffers)
     {
diff --git a/src/buffer_manager.hh b/src/buffer_manager.hh
index 7109dc11..1ee9f8fb 100644
--- a/src/buffer_manager.hh
+++ b/src/buffer_manager.hh
@@ -14,7 +14,7 @@ class Buffer;
 class BufferManager : public Singleton<BufferManager>
 {
 public:
-    typedef std::unordered_map<std::string, Buffer*> BufferMap;
+    typedef std::unordered_map<String, Buffer*> BufferMap;
 
     struct iterator : public BufferMap::const_iterator
     {
@@ -32,10 +32,10 @@ public:
     iterator begin() const { return iterator(m_buffers.begin()); }
     iterator end() const { return iterator(m_buffers.end()); }
 
-    Buffer* get_buffer(const std::string& name);
+    Buffer* get_buffer(const String& name);
 
-    CandidateList complete_buffername(const std::string& prefix,
-                                      size_t cursor_pos = std::string::npos);
+    CandidateList complete_buffername(const String& prefix,
+                                      size_t cursor_pos = String::npos);
 
 private:
     BufferMap m_buffers;
diff --git a/src/command_manager.cc b/src/command_manager.cc
index 3285c8c8..606c2513 100644
--- a/src/command_manager.cc
+++ b/src/command_manager.cc
@@ -12,14 +12,14 @@
 namespace Kakoune
 {
 
-void CommandManager::register_command(const std::string& command_name, Command command,
+void CommandManager::register_command(const String& command_name, Command command,
                                       unsigned flags,
                                       const CommandCompleter& completer)
 {
     m_commands[command_name] = CommandDescriptor { command, flags, completer };
 }
 
-void CommandManager::register_commands(const memoryview<std::string>& command_names, Command command,
+void CommandManager::register_commands(const memoryview<String>& command_names, Command command,
                                        unsigned flags,
                                        const CommandCompleter& completer)
 {
@@ -33,7 +33,7 @@ static bool is_blank(char c)
 }
 
 typedef std::vector<std::pair<size_t, size_t>> TokenList;
-static TokenList split(const std::string& line)
+static TokenList split(const String& line)
 {
     TokenList result;
 
@@ -76,18 +76,18 @@ static TokenList split(const std::string& line)
 
 struct command_not_found : runtime_error
 {
-    command_not_found(const std::string& command)
+    command_not_found(const String& command)
         : runtime_error(command + " : no such command") {}
 };
 
-void CommandManager::execute(const std::string& command_line,
+void CommandManager::execute(const String& command_line,
                              const Context& context)
 {
     TokenList tokens = split(command_line);
     if (tokens.empty())
         return;
 
-    std::vector<std::string> params;
+    std::vector<String> params;
     for (auto it = tokens.begin(); it != tokens.end(); ++it)
     {
         params.push_back(command_line.substr(it->first,
@@ -97,8 +97,8 @@ void CommandManager::execute(const std::string& command_line,
     execute(params, context);
 }
 
-static void shell_eval(std::vector<std::string>& params,
-                       const std::string& cmdline,
+static void shell_eval(std::vector<String>& params,
+                       const String& cmdline,
                        const Context& context)
 {
     int write_pipe[2];
@@ -113,13 +113,13 @@ static void shell_eval(std::vector<std::string>& params,
         close(read_pipe[1]);
         close(write_pipe[1]);
 
-        std::string output;
+        String output;
         char buffer[1024];
         while (size_t size = read(read_pipe[0], buffer, 1024))
         {
             if (size == -1)
                 break;
-            output += std::string(buffer, buffer+size);
+            output += String(buffer, buffer+size);
         }
         close(read_pipe[0]);
         waitpid(pid, NULL, 0);
@@ -161,7 +161,7 @@ void CommandManager::execute(const CommandParameters& params,
 
         if (end != begin)
         {
-            std::vector<std::string> expanded_params;
+            std::vector<String> expanded_params;
             auto command_it = m_commands.find(*begin);
 
             if (command_it == m_commands.end() and
@@ -209,7 +209,7 @@ void CommandManager::execute(const CommandParameters& params,
     }
 }
 
-Completions CommandManager::complete(const std::string& command_line, size_t cursor_pos)
+Completions CommandManager::complete(const String& command_line, size_t cursor_pos)
 {
     TokenList tokens = split(command_line);
 
@@ -227,8 +227,8 @@ Completions CommandManager::complete(const std::string& command_line, size_t cur
     {
         size_t cmd_start = tokens.empty() ? 0 : tokens[0].first;
         Completions result(cmd_start, cursor_pos);
-        std::string prefix = command_line.substr(cmd_start,
-                                                 cursor_pos - cmd_start);
+        String prefix = command_line.substr(cmd_start,
+                                            cursor_pos - cmd_start);
 
         for (auto& command : m_commands)
         {
@@ -240,7 +240,7 @@ Completions CommandManager::complete(const std::string& command_line, size_t cur
     }
 
     assert(not tokens.empty());
-    std::string command_name =
+    String command_name =
         command_line.substr(tokens[0].first,
                             tokens[0].second - tokens[0].first);
 
@@ -248,7 +248,7 @@ Completions CommandManager::complete(const std::string& command_line, size_t cur
     if (command_it == m_commands.end() or not command_it->second.completer)
         return Completions();
 
-    std::vector<std::string> params;
+    std::vector<String> params;
     for (auto it = tokens.begin() + 1; it != tokens.end(); ++it)
     {
         params.push_back(command_line.substr(it->first,
@@ -276,8 +276,8 @@ CandidateList PerArgumentCommandCompleter::operator()(const CommandParameters& p
     // it is possible to try to complete a new argument
     assert(token_to_complete <= params.size());
 
-    const std::string& argument = token_to_complete < params.size() ?
-                                  params[token_to_complete] : std::string();
+    const String& argument = token_to_complete < params.size() ?
+                             params[token_to_complete] : String();
     return m_completers[token_to_complete](argument, pos_in_token);
 }
 
diff --git a/src/command_manager.hh b/src/command_manager.hh
index 5e08d364..d6923ce2 100644
--- a/src/command_manager.hh
+++ b/src/command_manager.hh
@@ -1,11 +1,11 @@
 #ifndef command_manager_hh_INCLUDED
 #define command_manager_hh_INCLUDED
 
-#include <string>
 #include <unordered_map>
 #include <functional>
 #include <initializer_list>
 
+#include "string.hh"
 #include "utils.hh"
 #include "completion.hh"
 #include "memoryview.hh"
@@ -20,7 +20,7 @@ struct wrong_argument_count : runtime_error
     wrong_argument_count() : runtime_error("wrong argument count") {}
 };
 
-typedef memoryview<std::string> CommandParameters;
+typedef memoryview<String> CommandParameters;
 typedef std::function<void (const CommandParameters&,
                             const Context& context)> Command;
 
@@ -30,7 +30,7 @@ typedef std::function<CandidateList (const CommandParameters&,
 class PerArgumentCommandCompleter
 {
 public:
-    typedef std::function<CandidateList (const std::string&, size_t)> ArgumentCompleter;
+    typedef std::function<CandidateList (const String&, size_t)> ArgumentCompleter;
     typedef memoryview<ArgumentCompleter> ArgumentCompleterList;
 
     PerArgumentCommandCompleter(const ArgumentCompleterList& completers)
@@ -54,17 +54,17 @@ public:
         DeferredShellEval = 2,
     };
 
-    void execute(const std::string& command_line, const Context& context);
+    void execute(const String& command_line, const Context& context);
     void execute(const CommandParameters& params, const Context& context);
 
-    Completions complete(const std::string& command_line, size_t cursor_pos);
+    Completions complete(const String& command_line, size_t cursor_pos);
 
-    void register_command(const std::string& command_name,
+    void register_command(const String& command_name,
                           Command command,
                           unsigned flags = None,
                           const CommandCompleter& completer = CommandCompleter());
 
-    void register_commands(const memoryview<std::string>& command_names,
+    void register_commands(const memoryview<String>& command_names,
                            Command command,
                            unsigned flags = None,
                            const CommandCompleter& completer = CommandCompleter());
@@ -76,7 +76,7 @@ private:
         unsigned flags;
         CommandCompleter completer;
     };
-    std::unordered_map<std::string, CommandDescriptor> m_commands;
+    std::unordered_map<String, CommandDescriptor> m_commands;
 };
 
 }
diff --git a/src/completion.cc b/src/completion.cc
index 17482d14..8b1e8757 100644
--- a/src/completion.cc
+++ b/src/completion.cc
@@ -9,20 +9,20 @@
 namespace Kakoune
 {
 
-CandidateList complete_filename(const std::string& prefix,
+CandidateList complete_filename(const String& prefix,
                                 size_t cursor_pos)
 {
-    std::string real_prefix = prefix.substr(0, cursor_pos);
-    size_t dir_end = real_prefix.find_last_of('/');
-    std::string dirname = "./";
-    std::string dirprefix;
-    std::string fileprefix = real_prefix;
+    String real_prefix = prefix.substr(0, cursor_pos);
+    auto dir_end = std::find(real_prefix.begin(), real_prefix.end(), '/');
+    String dirname = "./";
+    String dirprefix;
+    String fileprefix = real_prefix;
 
-    if (dir_end != std::string::npos)
+    if (dir_end != real_prefix.end())
     {
-        dirname = real_prefix.substr(0, dir_end + 1);
+        dirname = String(real_prefix.begin(), dir_end + 1);
         dirprefix = dirname;
-        fileprefix = real_prefix.substr(dir_end + 1, std::string::npos);
+        fileprefix = String(dir_end + 1, real_prefix.end());
     }
 
     auto dir = auto_raii(opendir(dirname.c_str()), closedir);
@@ -33,13 +33,13 @@ CandidateList complete_filename(const std::string& prefix,
 
     while (dirent* entry = readdir(dir))
     {
-        std::string filename = entry->d_name;
+        String filename = entry->d_name;
         if (filename.empty())
             continue;
 
         if (filename.substr(0, fileprefix.length()) == fileprefix)
         {
-            std::string name = dirprefix + filename;
+            String name = dirprefix + filename;
             if (entry->d_type == DT_DIR)
                 name += '/';
             if (fileprefix.length() or filename[0] != '.')
diff --git a/src/completion.hh b/src/completion.hh
index af60ed1b..578076db 100644
--- a/src/completion.hh
+++ b/src/completion.hh
@@ -1,14 +1,15 @@
 #ifndef completion_hh_INCLUDED
 #define completion_hh_INCLUDED
 
-#include <string>
 #include <vector>
 #include <functional>
 
+#include "string.hh"
+
 namespace Kakoune
 {
 
-typedef std::vector<std::string> CandidateList;
+typedef std::vector<String> CandidateList;
 
 struct Completions
 {
@@ -23,12 +24,12 @@ struct Completions
         : start(start), end(end) {}
 };
 
-CandidateList complete_filename(const std::string& prefix,
-                                size_t cursor_pos = std::string::npos);
+CandidateList complete_filename(const String& prefix,
+                                size_t cursor_pos = -1);
 
-typedef std::function<Completions (const std::string&, size_t)> Completer;
+typedef std::function<Completions (const String&, size_t)> Completer;
 
-inline Completions complete_nothing(const std::string&, size_t cursor_pos)
+inline Completions complete_nothing(const String&, size_t cursor_pos)
 {
     return Completions(cursor_pos, cursor_pos);
 }
diff --git a/src/debug.cc b/src/debug.cc
index d170f843..84f52581 100644
--- a/src/debug.cc
+++ b/src/debug.cc
@@ -9,7 +9,7 @@ namespace Kakoune
 
 static Buffer& get_or_create_debug_buffer()
 {
-    static const std::string debug_buffer_name("*debug*");
+    static const String debug_buffer_name("*debug*");
     Buffer* buffer = BufferManager::instance().get_buffer(debug_buffer_name);
 
     if (not buffer)
@@ -19,7 +19,7 @@ static Buffer& get_or_create_debug_buffer()
     return *buffer;
 }
 
-void write_debug(const std::string& str)
+void write_debug(const String& str)
 {
     Buffer& debug_buffer = get_or_create_debug_buffer();
     Editor editor(debug_buffer);
diff --git a/src/debug.hh b/src/debug.hh
index 7fdb226c..5f21d84c 100644
--- a/src/debug.hh
+++ b/src/debug.hh
@@ -1,12 +1,12 @@
 #ifndef debug_hh_INCLUDED
 #define debug_hh_INCLUDED
 
-#include <string>
+#include "string.hh"
 
 namespace Kakoune
 {
 
-void write_debug(const std::string& str);
+void write_debug(const String& str);
 
 }
 
diff --git a/src/display_buffer.hh b/src/display_buffer.hh
index aeafae14..36b4803e 100644
--- a/src/display_buffer.hh
+++ b/src/display_buffer.hh
@@ -1,11 +1,10 @@
 #ifndef display_buffer_hh_INCLUDED
 #define display_buffer_hh_INCLUDED
 
-#include <string>
 #include <vector>
 
+#include "string.hh"
 #include "line_and_column.hh"
-
 #include "buffer.hh"
 
 namespace Kakoune
diff --git a/src/editor.cc b/src/editor.cc
index c0bb6f76..d1253705 100644
--- a/src/editor.cc
+++ b/src/editor.cc
@@ -72,7 +72,7 @@ void Editor::append(const memoryview<String>& strings)
     do_insert<true>(*this, strings);
 }
 
-void Editor::replace(const std::string& string)
+void Editor::replace(const String& string)
 {
     scoped_edition edition(*this);
     erase();
@@ -228,7 +228,7 @@ void Editor::check_invariant() const
 
 struct id_not_unique : public runtime_error
 {
-    id_not_unique(const std::string& id)
+    id_not_unique(const String& id)
         : runtime_error("id not unique: " + id) {}
 };
 
@@ -239,12 +239,12 @@ void Editor::add_filter(FilterAndId&& filter)
     m_filters.append(std::forward<FilterAndId>(filter));
 }
 
-void Editor::remove_filter(const std::string& id)
+void Editor::remove_filter(const String& id)
 {
     m_filters.remove(id);
 }
 
-CandidateList Editor::complete_filterid(const std::string& prefix,
+CandidateList Editor::complete_filterid(const String& prefix,
                                         size_t cursor_pos)
 {
     return m_filters.complete_id<str_to_str>(prefix, cursor_pos);
diff --git a/src/editor.hh b/src/editor.hh
index 70ea9d64..b41e0a81 100644
--- a/src/editor.hh
+++ b/src/editor.hh
@@ -54,10 +54,10 @@ public:
     bool redo();
 
     void add_filter(FilterAndId&& filter);
-    void remove_filter(const std::string& id);
+    void remove_filter(const String& id);
 
-    CandidateList complete_filterid(const std::string& prefix,
-                                    size_t cursor_pos = std::string::npos);
+    CandidateList complete_filterid(const String& prefix,
+                                    size_t cursor_pos = String::npos);
 
     bool is_editing() const { return m_edition_level!= 0; }
 
@@ -76,7 +76,7 @@ private:
 
     Buffer&                             m_buffer;
     std::vector<SelectionList>          m_selections;
-    idvaluemap<std::string, FilterFunc> m_filters;
+    idvaluemap<String, FilterFunc> m_filters;
 };
 
 struct scoped_edition
diff --git a/src/exception.cc b/src/exception.cc
index 0d816062..9bd8f6a2 100644
--- a/src/exception.cc
+++ b/src/exception.cc
@@ -1,12 +1,12 @@
 #include "exception.hh"
 
-#include <string>
+#include "string.hh"
 #include <typeinfo>
 
 namespace Kakoune
 {
 
-std::string exception::description() const
+String exception::description() const
 {
     return typeid(*this).name();
 }
diff --git a/src/exception.hh b/src/exception.hh
index 89188e63..5aab02f6 100644
--- a/src/exception.hh
+++ b/src/exception.hh
@@ -1,7 +1,7 @@
 #ifndef exception_hh_INCLUDED
 #define exception_hh_INCLUDED
 
-#include <string>
+#include "string.hh"
 
 namespace Kakoune
 {
@@ -9,18 +9,18 @@ namespace Kakoune
 struct exception
 {
     virtual ~exception() {}
-    virtual std::string description() const;
+    virtual String description() const;
 };
 
 struct runtime_error : exception
 {
-    runtime_error(const std::string& description)
+    runtime_error(const String& description)
         : m_description(description) {}
 
-    std::string description() const { return m_description; }
+    String description() const { return m_description; }
 
 private:
-    std::string m_description;
+    String m_description;
 };
 
 struct logic_error : exception
diff --git a/src/file.cc b/src/file.cc
index fdb50927..dd8f93de 100644
--- a/src/file.cc
+++ b/src/file.cc
@@ -18,13 +18,13 @@ bool isidentifier(char c)
     return std::isalnum(c) or c == '_';
 }
 
-std::string parse_filename(const std::string& filename)
+String parse_filename(const String& filename)
 {
     if (filename.length() > 2 and filename[0] == '~' and filename[1] == '/')
         return parse_filename("$HOME/" + filename.substr(2));
 
     size_t pos = 0;
-    std::string result;
+    String result;
     for (size_t i = 0; i < filename.length(); ++i)
     {
         if (filename[i] == '$' and (i == 0 or filename[i-1] != '\\'))
@@ -33,7 +33,7 @@ std::string parse_filename(const std::string& filename)
             size_t end = i+1;
             while (end != filename.length() and isidentifier(filename[end]))
                 ++end;
-            std::string var_name = filename.substr(i+1, end - i - 1);
+            String var_name = filename.substr(i+1, end - i - 1);
             const char* var_value = getenv(var_name.c_str());
             if (var_value)
                 result += var_value;
@@ -47,7 +47,7 @@ std::string parse_filename(const std::string& filename)
     return result;
 }
 
-std::string read_file(const std::string& filename)
+String read_file(const String& filename)
 {
    int fd = open(filename.c_str(), O_RDONLY);
     if (fd == -1)
@@ -58,7 +58,7 @@ std::string read_file(const std::string& filename)
         throw file_access_error(filename, strerror(errno));
     }
 
-    std::string content;
+    String content;
     char buf[256];
     while (true)
     {
@@ -66,15 +66,15 @@ std::string read_file(const std::string& filename)
         if (size == -1 or size == 0)
             break;
 
-        content += std::string(buf, size);
+        content += String(buf, buf + size);
     }
     close(fd);
     return content;
 }
 
-Buffer* create_buffer_from_file(const std::string& filename)
+Buffer* create_buffer_from_file(const String& filename)
 {
-    std::string content = read_file(filename);
+    String content = read_file(filename);
 
     if (Buffer* buffer = BufferManager::instance().get_buffer(filename))
         delete buffer;
@@ -82,7 +82,7 @@ Buffer* create_buffer_from_file(const std::string& filename)
     return new Buffer(filename, Buffer::Type::File, content);
 }
 
-void write_buffer_to_file(const Buffer& buffer, const std::string& filename)
+void write_buffer_to_file(const Buffer& buffer, const String& filename)
 {
     int fd = open(filename.c_str(), O_CREAT | O_WRONLY | O_TRUNC, 0644);
     if (fd == -1)
@@ -91,8 +91,8 @@ void write_buffer_to_file(const Buffer& buffer, const std::string& filename)
     for (size_t i = 0; i < buffer.line_count(); ++i)
     {
         const String& content = buffer.line_content(i);
-        ssize_t count = content.length() * sizeof(BufferChar);
         const char* ptr = content.c_str();
+        ssize_t count   = content.size();
 
         while (count)
         {
diff --git a/src/file.hh b/src/file.hh
index 3f1c599b..e816d5b4 100644
--- a/src/file.hh
+++ b/src/file.hh
@@ -1,7 +1,7 @@
 #ifndef file_hh_INCLUDED
 #define file_hh_INCLUDED
 
-#include <string>
+#include "string.hh"
 
 #include "exception.hh"
 
@@ -11,25 +11,25 @@ namespace Kakoune
 struct file_access_error : runtime_error
 {
 public:
-    file_access_error(const std::string& filename,
-                      const std::string& error_desc)
+    file_access_error(const String& filename,
+                      const String& error_desc)
         : runtime_error(filename + ": " + error_desc) {}
 };
 
 struct file_not_found : file_access_error
 {
-    file_not_found(const std::string& filename)
+    file_not_found(const String& filename)
         : file_access_error(filename, "file not found") {}
 };
 
 class Buffer;
 
 // parse ~/ and $env values in filename and returns the translated filename
-std::string parse_filename(const std::string& filename);
+String parse_filename(const String& filename);
 
-std::string read_file(const std::string& filename);
-Buffer* create_buffer_from_file(const std::string& filename);
-void write_buffer_to_file(const Buffer& buffer, const std::string& filename);
+String read_file(const String& filename);
+Buffer* create_buffer_from_file(const String& filename);
+void write_buffer_to_file(const Buffer& buffer, const String& filename);
 
 }
 
diff --git a/src/filter.hh b/src/filter.hh
index 68930960..8e35744a 100644
--- a/src/filter.hh
+++ b/src/filter.hh
@@ -1,7 +1,7 @@
 #ifndef filter_hh_INCLUDED
 #define filter_hh_INCLUDED
 
-#include <string>
+#include "string.hh"
 #include <functional>
 
 namespace Kakoune
@@ -15,7 +15,7 @@ class Modification;
 // prior to it's application.
 
 typedef std::function<void (Buffer& buffer, Modification& modification)> FilterFunc;
-typedef std::pair<std::string, FilterFunc> FilterAndId;
+typedef std::pair<String, FilterFunc> FilterAndId;
 
 }
 
diff --git a/src/filter_registry.cc b/src/filter_registry.cc
index 45e565f5..15422d60 100644
--- a/src/filter_registry.cc
+++ b/src/filter_registry.cc
@@ -8,11 +8,11 @@ namespace Kakoune
 
 struct factory_not_found : public runtime_error
 {
-    factory_not_found(const std::string& name)
+    factory_not_found(const String& name)
         : runtime_error("filter factory not found '" + name + "'") {}
 };
 
-void FilterRegistry::register_factory(const std::string& name,
+void FilterRegistry::register_factory(const String& name,
                                       const FilterFactory& factory)
 {
     assert(not m_factories.contains(name));
@@ -20,7 +20,7 @@ void FilterRegistry::register_factory(const std::string& name,
 }
 
 void FilterRegistry::add_filter_to_window(Window& window,
-                                          const std::string& name,
+                                          const String& name,
                                           const FilterParameters& parameters)
 {
     auto it = m_factories.find(name);
@@ -30,7 +30,7 @@ void FilterRegistry::add_filter_to_window(Window& window,
     window.add_filter(it->second(window, parameters));
 }
 
-CandidateList FilterRegistry::complete_filter(const std::string& prefix,
+CandidateList FilterRegistry::complete_filter(const String& prefix,
                                               size_t cursor_pos)
 {
     return m_factories.complete_id<str_to_str>(prefix, cursor_pos);
diff --git a/src/filter_registry.hh b/src/filter_registry.hh
index a5069362..ed2e90ee 100644
--- a/src/filter_registry.hh
+++ b/src/filter_registry.hh
@@ -1,9 +1,9 @@
 #ifndef filter_registry_h_INCLUDED
 #define filter_registry_h_INCLUDED
 
-#include <string>
 #include <unordered_map>
 
+#include "string.hh"
 #include "filter.hh"
 #include "utils.hh"
 #include "completion.hh"
@@ -15,7 +15,7 @@ namespace Kakoune
 
 class Window;
 
-typedef memoryview<std::string> FilterParameters;
+typedef memoryview<String> FilterParameters;
 
 typedef std::function<FilterAndId (Window& window,
                                    const FilterParameters& params)> FilterFactory;
@@ -23,18 +23,18 @@ typedef std::function<FilterAndId (Window& window,
 class FilterRegistry : public Singleton<FilterRegistry>
 {
 public:
-    void register_factory(const std::string& name,
+    void register_factory(const String& name,
                           const FilterFactory& factory);
 
     void add_filter_to_window(Window& window,
-                              const std::string& factory_name,
+                              const String& factory_name,
                               const FilterParameters& parameters);
 
-    CandidateList complete_filter(const std::string& prefix,
+    CandidateList complete_filter(const String& prefix,
                                   size_t cursor_pos);
 
 private:
-    idvaluemap<std::string, FilterFactory> m_factories;
+    idvaluemap<String, FilterFactory> m_factories;
 };
 
 }
diff --git a/src/filters.cc b/src/filters.cc
index 9d1589f4..960c5511 100644
--- a/src/filters.cc
+++ b/src/filters.cc
@@ -56,7 +56,9 @@ void expand_tabulations(Buffer& buffer, Modification& modification)
         }
 
         int count = tabstop - (column % tabstop);
-        modification.content = std::string(count, ' ');
+        modification.content.clear();
+        for (int i = 0; i < count; ++i)
+            modification.content += ' ';
     }
 }
 
@@ -64,7 +66,7 @@ template<void (*filter_func)(Buffer&, Modification&)>
 class SimpleFilterFactory
 {
 public:
-    SimpleFilterFactory(const std::string& id) : m_id(id) {}
+    SimpleFilterFactory(const String& id) : m_id(id) {}
 
     FilterAndId operator()(Window& window,
                            const FilterParameters& params) const
@@ -72,7 +74,7 @@ public:
         return FilterAndId(m_id, FilterFunc(filter_func));
     }
 private:
-    std::string m_id;
+    String m_id;
 };
 
 void register_filters()
diff --git a/src/highlighter.hh b/src/highlighter.hh
index 5c9ce5e9..5f6d58d9 100644
--- a/src/highlighter.hh
+++ b/src/highlighter.hh
@@ -1,7 +1,7 @@
 #ifndef highlighter_hh_INCLUDED
 #define highlighter_hh_INCLUDED
 
-#include <string>
+#include "string.hh"
 #include <functional>
 #include "memoryview.hh"
 
@@ -16,8 +16,8 @@ class DisplayBuffer;
 // buffer content (folding for example)
 
 typedef std::function<void (DisplayBuffer& display_buffer)> HighlighterFunc;
-typedef std::pair<std::string, HighlighterFunc> HighlighterAndId;
-typedef memoryview<std::string> HighlighterParameters;
+typedef std::pair<String, HighlighterFunc> HighlighterAndId;
+typedef memoryview<String> HighlighterParameters;
 
 
 }
diff --git a/src/highlighter_group.cc b/src/highlighter_group.cc
index e87c4816..2c86c62f 100644
--- a/src/highlighter_group.cc
+++ b/src/highlighter_group.cc
@@ -20,12 +20,12 @@ void HighlighterGroup::append(HighlighterAndId&& highlighter)
     m_highlighters.append(std::forward<HighlighterAndId>(highlighter));
 }
 
-void HighlighterGroup::remove(const std::string& id)
+void HighlighterGroup::remove(const String& id)
 {
     m_highlighters.remove(id);
 }
 
-HighlighterGroup& HighlighterGroup::get_group(const std::string& id)
+HighlighterGroup& HighlighterGroup::get_group(const String& id)
 {
     auto it = m_highlighters.find(id);
     if (it == m_highlighters.end())
@@ -38,18 +38,18 @@ HighlighterGroup& HighlighterGroup::get_group(const std::string& id)
 }
 
 
-CandidateList HighlighterGroup::complete_id(const std::string& prefix,
+CandidateList HighlighterGroup::complete_id(const String& prefix,
                                             size_t cursor_pos)
 {
     return m_highlighters.complete_id<str_to_str>(prefix, cursor_pos);
 }
 
-CandidateList HighlighterGroup::complete_group_id(const std::string& prefix,
+CandidateList HighlighterGroup::complete_group_id(const String& prefix,
                                                   size_t cursor_pos)
 {
     return m_highlighters.complete_id_if<str_to_str>(
         prefix, cursor_pos,
-        [](std::pair<std::string, HighlighterFunc>& func)
+        [](std::pair<String, HighlighterFunc>& func)
         { return func.second.target<HighlighterGroup>() != nullptr; });
 }
 
diff --git a/src/highlighter_group.hh b/src/highlighter_group.hh
index 1157a48c..d6374f30 100644
--- a/src/highlighter_group.hh
+++ b/src/highlighter_group.hh
@@ -16,15 +16,15 @@ public:
     void operator()(DisplayBuffer& display_buffer);
 
     void append(HighlighterAndId&& highlighter);
-    void remove(const std::string& id);
+    void remove(const String& id);
 
-    HighlighterGroup& get_group(const std::string& id);
+    HighlighterGroup& get_group(const String& id);
 
-    CandidateList complete_id(const std::string& prefix, size_t cursor_pos);
-    CandidateList complete_group_id(const std::string& prefix, size_t cursor_pos);
+    CandidateList complete_id(const String& prefix, size_t cursor_pos);
+    CandidateList complete_group_id(const String& prefix, size_t cursor_pos);
 
 private:
-    idvaluemap<std::string, HighlighterFunc> m_highlighters;
+    idvaluemap<String, HighlighterFunc> m_highlighters;
 };
 
 }
diff --git a/src/highlighter_registry.cc b/src/highlighter_registry.cc
index 9eb0b3b1..0f5145a9 100644
--- a/src/highlighter_registry.cc
+++ b/src/highlighter_registry.cc
@@ -9,11 +9,11 @@ namespace Kakoune
 
 struct factory_not_found : public runtime_error
 {
-    factory_not_found(const std::string& name)
+    factory_not_found(const String& name)
         : runtime_error("highlighter factory not found '" + name + "'") {}
 };
 
-void HighlighterRegistry::register_factory(const std::string& name,
+void HighlighterRegistry::register_factory(const String& name,
                                            const HighlighterFactory& factory)
 {
     assert(not m_factories.contains(name));
@@ -21,7 +21,7 @@ void HighlighterRegistry::register_factory(const std::string& name,
 }
 
 void HighlighterRegistry::add_highlighter_to_window(Window& window,
-                                                    const std::string& name,
+                                                    const String& name,
                                                     const HighlighterParameters& parameters)
 {
     auto it = m_factories.find(name);
@@ -33,7 +33,7 @@ void HighlighterRegistry::add_highlighter_to_window(Window& window,
 
 void HighlighterRegistry::add_highlighter_to_group(Window& window,
                                                    HighlighterGroup& group,
-                                                   const std::string& name,
+                                                   const String& name,
                                                    const HighlighterParameters& parameters)
 {
     auto it = m_factories.find(name);
@@ -43,7 +43,7 @@ void HighlighterRegistry::add_highlighter_to_group(Window& window,
     group.append(it->second(window, parameters));
 }
 
-CandidateList HighlighterRegistry::complete_highlighter(const std::string& prefix,
+CandidateList HighlighterRegistry::complete_highlighter(const String& prefix,
                                                         size_t cursor_pos)
 {
     return m_factories.complete_id<str_to_str>(prefix, cursor_pos);
diff --git a/src/highlighter_registry.hh b/src/highlighter_registry.hh
index cd77fdc9..17daa89b 100644
--- a/src/highlighter_registry.hh
+++ b/src/highlighter_registry.hh
@@ -1,7 +1,7 @@
 #ifndef highlighter_registry_h_INCLUDED
 #define highlighter_registry_h_INCLUDED
 
-#include <string>
+#include "string.hh"
 #include <unordered_map>
 
 #include "highlighter.hh"
@@ -21,23 +21,23 @@ typedef std::function<HighlighterAndId (Window& window,
 class HighlighterRegistry : public Singleton<HighlighterRegistry>
 {
 public:
-    void register_factory(const std::string& name,
+    void register_factory(const String& name,
                           const HighlighterFactory& factory);
 
     void add_highlighter_to_window(Window& window,
-                                  const std::string& factory_name,
+                                  const String& factory_name,
                                   const HighlighterParameters& parameters);
 
     void add_highlighter_to_group(Window& window,
                                   HighlighterGroup& group,
-                                  const std::string& factory_name,
+                                  const String& factory_name,
                                   const HighlighterParameters& parameters);
 
-    CandidateList complete_highlighter(const std::string& prefix,
+    CandidateList complete_highlighter(const String& prefix,
                                       size_t cursor_pos);
 
 private:
-    idvaluemap<std::string, HighlighterFactory> m_factories;
+    idvaluemap<String, HighlighterFactory> m_factories;
 };
 
 }
diff --git a/src/highlighters.cc b/src/highlighters.cc
index ed0fa63c..7becf1d0 100644
--- a/src/highlighters.cc
+++ b/src/highlighters.cc
@@ -5,7 +5,7 @@
 #include "display_buffer.hh"
 #include "highlighter_registry.hh"
 #include "highlighter_group.hh"
-#include <boost/regex.hpp>
+#include "regex.hh"
 
 namespace Kakoune
 {
@@ -15,7 +15,7 @@ using namespace std::placeholders;
 void colorize_regex_range(DisplayBuffer& display_buffer,
                           const BufferIterator& range_begin,
                           const BufferIterator& range_end,
-                          const boost::regex& ex,
+                          const Regex& ex,
                           Color fg_color, Color bg_color = Color::Default)
 {
     assert(range_begin <= range_end);
@@ -29,9 +29,8 @@ void colorize_regex_range(DisplayBuffer& display_buffer,
     BufferIterator display_end   = std::min(range_end,
                                             display_buffer.back().end());
 
-    boost::regex_iterator<BufferIterator> re_it(display_begin, display_end,
-                                                ex, boost::match_nosubs);
-    boost::regex_iterator<BufferIterator> re_end;
+    RegexIterator re_it(display_begin, display_end, ex, boost::match_nosubs);
+    RegexIterator re_end;
     DisplayBuffer::iterator atom_it = display_buffer.begin();
     for (; re_it != re_end; ++re_it)
     {
@@ -65,14 +64,14 @@ void colorize_regex_range(DisplayBuffer& display_buffer,
 }
 
 void colorize_regex(DisplayBuffer& display_buffer,
-                    const boost::regex& ex,
+                    const Regex& ex,
                     Color fg_color, Color bg_color = Color::Default)
 {
     colorize_regex_range(display_buffer, display_buffer.front().begin(),
                          display_buffer.back().end(), ex, fg_color, bg_color);
 }
 
-Color parse_color(const std::string& color)
+Color parse_color(const String& color)
 {
     if (color == "default") return Color::Default;
     if (color == "black")   return Color::Black;
@@ -92,12 +91,12 @@ HighlighterAndId colorize_regex_factory(Window& window,
     if (params.size() != 3)
         throw runtime_error("wrong parameter count");
 
-    boost::regex ex(params[0]);
+    Regex ex(params[0].begin(), params[0].end());
 
     Color fg_color = parse_color(params[1]);
     Color bg_color = parse_color(params[2]);
 
-    std::string id = "colre'" + params[0] + "'";
+    String id = "colre'" + params[0] + "'";
 
     return HighlighterAndId(id, std::bind(colorize_regex, _1,
                                           ex, fg_color, bg_color));
@@ -133,8 +132,10 @@ void expand_tabulations(Window& window, DisplayBuffer& display_buffer)
                 }
 
                 int count = tabstop - (column % tabstop);
-                display_buffer.replace_atom_content(atom_it,
-                                                    std::string(count, ' '));
+                String padding;
+                for (int i = 0; i < count; ++i)
+                    padding += ' ';
+                display_buffer.replace_atom_content(atom_it, padding);
             }
         }
     }
@@ -271,7 +272,7 @@ template<void (*highlighter_func)(DisplayBuffer&)>
 class SimpleHighlighterFactory
 {
 public:
-    SimpleHighlighterFactory(const std::string& id) : m_id(id) {}
+    SimpleHighlighterFactory(const String& id) : m_id(id) {}
 
     HighlighterAndId operator()(Window& window,
                                 const HighlighterParameters& params) const
@@ -279,14 +280,14 @@ public:
         return HighlighterAndId(m_id, HighlighterFunc(highlighter_func));
     }
 private:
-    std::string m_id;
+    String m_id;
 };
 
 template<void (*highlighter_func)(Window&, DisplayBuffer&)>
 class WindowHighlighterFactory
 {
 public:
-    WindowHighlighterFactory(const std::string& id) : m_id(id) {}
+    WindowHighlighterFactory(const String& id) : m_id(id) {}
 
     HighlighterAndId operator()(Window& window,
                                 const HighlighterParameters& params) const
@@ -294,7 +295,7 @@ public:
         return HighlighterAndId(m_id, std::bind(highlighter_func, std::ref(window), _1));
     }
 private:
-    std::string m_id;
+    String m_id;
 };
 
 HighlighterAndId highlighter_group_factory(Window& window,
diff --git a/src/hook_manager.cc b/src/hook_manager.cc
index 283d7b3d..846b922d 100644
--- a/src/hook_manager.cc
+++ b/src/hook_manager.cc
@@ -3,13 +3,13 @@
 namespace Kakoune
 {
 
-void HookManager::add_hook(const std::string& hook_name, HookFunc hook)
+void HookManager::add_hook(const String& hook_name, HookFunc hook)
 {
     m_hook[hook_name].push_back(hook);
 }
 
-void HookManager::run_hook(const std::string& hook_name,
-                           const std::string& param,
+void HookManager::run_hook(const String& hook_name,
+                           const String& param,
                            const Context& context) const
 {
     auto hook_list_it = m_hook.find(hook_name);
diff --git a/src/hook_manager.hh b/src/hook_manager.hh
index 85b6cc28..21d087c7 100644
--- a/src/hook_manager.hh
+++ b/src/hook_manager.hh
@@ -9,17 +9,17 @@ namespace Kakoune
 {
 
 class Context;
-typedef std::function<void (const std::string&, const Context&)> HookFunc;
+typedef std::function<void (const String&, const Context&)> HookFunc;
 
 class HookManager
 {
 public:
-    void add_hook(const std::string& hook_name, HookFunc hook);
-    void run_hook(const std::string& hook_name, const std::string& param,
+    void add_hook(const String& hook_name, HookFunc hook);
+    void run_hook(const String& hook_name, const String& param,
                   const Context& context) const;
 
 private:
-    std::unordered_map<std::string, std::vector<HookFunc>> m_hook;
+    std::unordered_map<String, std::vector<HookFunc>> m_hook;
 };
 
 class GlobalHookManager : public HookManager,
diff --git a/src/idvaluemap.hh b/src/idvaluemap.hh
index 387e6fb0..a6eb315d 100644
--- a/src/idvaluemap.hh
+++ b/src/idvaluemap.hh
@@ -63,28 +63,28 @@ public:
         }
     }
 
-    template<std::string (*id_to_string)(const _Id&),
+    template<String (*id_to_string)(const _Id&),
              typename _Condition>
-    CandidateList complete_id_if(const std::string& prefix,
+    CandidateList complete_id_if(const String& prefix,
                                  size_t cursor_pos,
                                  _Condition condition)
     {
-        std::string real_prefix = prefix.substr(0, cursor_pos);
+        String real_prefix = prefix.substr(0, cursor_pos);
         CandidateList result;
         for (auto& value : m_content)
         {
             if (not condition(value))
                 continue;
 
-            std::string id_str = id_to_string(value.first);
+            String id_str = id_to_string(value.first);
             if (id_str.substr(0, real_prefix.length()) == real_prefix)
                 result.push_back(std::move(id_str));
         }
         return result;
     }
 
-    template<std::string (*id_to_string)(const _Id&)>
-    CandidateList complete_id(const std::string& prefix,
+    template<String (*id_to_string)(const _Id&)>
+    CandidateList complete_id(const String& prefix,
                               size_t cursor_pos)
     {
         return complete_id_if<id_to_string>(
diff --git a/src/keys.cc b/src/keys.cc
index a2f65e2c..042e8daa 100644
--- a/src/keys.cc
+++ b/src/keys.cc
@@ -5,13 +5,13 @@
 namespace Kakoune
 {
 
-static std::unordered_map<std::string, char> keynamemap = {
+static std::unordered_map<String, Character> keynamemap = {
     { "ret", '\n' },
     { "space", ' ' },
     { "esc", 27 }
 };
 
-KeyList parse_keys(const std::string& str)
+KeyList parse_keys(const String& str)
 {
     KeyList result;
     for (size_t pos = 0; pos < str.length(); ++pos)
@@ -26,7 +26,7 @@ KeyList parse_keys(const std::string& str)
             {
                 Key::Modifiers modifier = Key::Modifiers::None;
 
-                std::string keyname = str.substr(pos+1, end_pos - pos - 1);
+                String keyname = str.substr(pos+1, end_pos - pos - 1);
                 if (keyname.length() > 2)
                 {
                     if (tolower(keyname[0]) == 'c' and keyname[1] == '-')
diff --git a/src/keys.hh b/src/keys.hh
index 3ff158be..0884276e 100644
--- a/src/keys.hh
+++ b/src/keys.hh
@@ -2,7 +2,7 @@
 #define keys_hh_INCLUDED
 
 #include <vector>
-#include <string>
+#include "string.hh"
 
 namespace Kakoune
 {
@@ -18,9 +18,9 @@ struct Key
     };
 
     Modifiers modifiers;
-    char      key;
+    Character key;
 
-    Key(Modifiers modifiers, char key)
+    Key(Modifiers modifiers, Character key)
         : modifiers(modifiers), key(key) {}
 
     bool operator==(const Key& other) const
@@ -29,7 +29,7 @@ struct Key
 
 typedef std::vector<Key> KeyList;
 
-KeyList parse_keys(const std::string& str);
+KeyList parse_keys(const String& str);
 
 }
 
diff --git a/src/main.cc b/src/main.cc
index b001f648..0d5361cf 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -15,9 +15,9 @@
 #include "option_manager.hh"
 #include "context.hh"
 #include "ncurses.hh"
+#include "regex.hh"
 
 #include <unordered_map>
-#include <boost/regex.hpp>
 #include <sys/types.h>
 #include <sys/wait.h>
 
@@ -36,7 +36,7 @@ void draw_editor_ifn(Editor& editor)
 }
 
 PromptFunc prompt_func;
-std::string prompt(const std::string& text, Completer completer = complete_nothing)
+String prompt(const String& text, Completer completer = complete_nothing)
 {
     return prompt_func(text, completer);
 }
@@ -67,7 +67,7 @@ bool insert_char(IncrementalInserter& inserter, const Key& key)
         case 27:
             return false;
         default:
-            inserter.insert(std::string() + key.key);
+            inserter.insert(String() + key.key);
         }
         break;
     case Key::Modifiers::Control:
@@ -91,10 +91,10 @@ bool insert_char(IncrementalInserter& inserter, const Key& key)
             break;
         }
         case 'm':
-            inserter.insert(std::string() + '\n');
+            inserter.insert(String() + '\n');
             break;
         case 'i':
-            inserter.insert(std::string() + '\t');
+            inserter.insert(String() + '\t');
             break;
         case 'd':
             inserter.move_cursors({0, -1});
@@ -187,7 +187,7 @@ void do_go(Editor& editor, int count)
 
 Context main_context;
 
-Buffer* open_or_create(const std::string& filename)
+Buffer* open_or_create(const String& filename)
 {
     Buffer* buffer = NULL;
     try
@@ -208,7 +208,7 @@ void edit(const CommandParameters& params, const Context& context)
     if (params.size() == 0 or params.size() > 3)
         throw wrong_argument_count();
 
-    std::string filename = params[0];
+    String filename = params[0];
 
     Buffer* buffer = nullptr;
     if (not force_reload)
@@ -236,7 +236,7 @@ void write_buffer(const CommandParameters& params, const Context& context)
         throw wrong_argument_count();
 
     Buffer& buffer = context.window().buffer();
-    std::string filename = params.empty() ? buffer.name()
+    String filename = params.empty() ? buffer.name()
                                           : parse_filename(params[0]);
 
     write_buffer_to_file(buffer, filename);
@@ -253,7 +253,7 @@ void quit(const CommandParameters& params, const Context& context)
 
     if (not force)
     {
-        std::vector<std::string> names;
+        std::vector<String> names;
         for (auto& buffer : BufferManager::instance())
         {
             if (buffer.type() != Buffer::Type::Scratch and buffer.is_modified())
@@ -261,7 +261,7 @@ void quit(const CommandParameters& params, const Context& context)
         }
         if (not names.empty())
         {
-            std::string message = "modified buffers remaining: [";
+            String message = "modified buffers remaining: [";
             for (auto it = names.begin(); it != names.end(); ++it)
             {
                 if (it != names.begin())
@@ -387,11 +387,12 @@ void add_hook(const CommandParameters& params, const Context& context)
     if (params.size() < 4)
         throw wrong_argument_count();
 
-    std::string regex = params[2];
-    std::vector<std::string> hook_params(params.begin()+3, params.end());
+    String regex = params[2];
+    std::vector<String> hook_params(params.begin()+3, params.end());
 
-    auto hook_func = [=](const std::string& param, const Context& context) {
-        if (boost::regex_match(param, boost::regex(regex)))
+    auto hook_func = [=](const String& param, const Context& context) {
+        if (boost::regex_match(param.begin(), param.end(),
+                               Regex(regex.begin(), regex.end())))
             CommandManager::instance().execute(hook_params, context);
     };
 
@@ -410,7 +411,7 @@ void define_command(const CommandParameters& params, const Context& context)
 
     if (params[0] == "-env-params")
     {
-        std::vector<std::string> cmd_params(params.begin() + 2, params.end());
+        std::vector<String> cmd_params(params.begin() + 2, params.end());
         CommandManager::instance().register_command(params[1],
              [=](const CommandParameters& params, const Context& context) {
                 char param_name[] = "kak_param0";
@@ -427,10 +428,10 @@ void define_command(const CommandParameters& params, const Context& context)
     }
     else if (params[0] == "-append-params")
     {
-        std::vector<std::string> cmd_params(params.begin() + 2, params.end());
+        std::vector<String> cmd_params(params.begin() + 2, params.end());
         CommandManager::instance().register_command(params[1],
              [=](const CommandParameters& params, const Context& context) {
-                std::vector<std::string> merged_params = cmd_params;
+                std::vector<String> merged_params = cmd_params;
                 for (auto& param : params)
                     merged_params.push_back(param);
                 CommandManager::instance().execute(merged_params, context);
@@ -438,7 +439,7 @@ void define_command(const CommandParameters& params, const Context& context)
     }
     else
     {
-        std::vector<std::string> cmd_params(params.begin() + 1, params.end());
+        std::vector<String> cmd_params(params.begin() + 1, params.end());
         CommandManager::instance().register_command(params[0],
              [=](const CommandParameters& params, const Context& context) {
                  if (not params.empty())
@@ -450,7 +451,7 @@ void define_command(const CommandParameters& params, const Context& context)
 
 void echo_message(const CommandParameters& params, const Context& context)
 {
-    std::string message;
+    String message;
     for (auto& param : params)
         message += param + " ";
     NCurses::print_status(message);
@@ -462,13 +463,13 @@ void exec_commands_in_file(const CommandParameters& params,
     if (params.size() != 1)
         throw wrong_argument_count();
 
-    std::string file_content = read_file(parse_filename(params[0]));
+    String file_content = read_file(parse_filename(params[0]));
     CommandManager& cmd_manager = CommandManager::instance();
 
     size_t pos = 0;
     size_t length = file_content.length();
     bool   cat_with_previous = false;
-    std::string command_line;
+    String command_line;
     while (true)
     {
          if (not cat_with_previous)
@@ -489,7 +490,7 @@ void exec_commands_in_file(const CommandParameters& params,
 
                  if (end_pos == length)
                  {
-                     NCurses::print_status(std::string("unterminated '") + delimiter + "' string");
+                     NCurses::print_status(String("unterminated '") + delimiter + "' string");
                      return;
                  }
 
@@ -528,7 +529,7 @@ void exec_commands_in_runtime_file(const CommandParameters& params,
     if (params.size() != 1)
         throw wrong_argument_count();
 
-    const std::string& filename = params[0];
+    const String& filename = params[0];
     char buffer[2048];
 #if defined(__linux__)
     ssize_t res = readlink("/proc/self/exe", buffer, 2048 - filename.length());
@@ -589,15 +590,15 @@ void do_pipe(Editor& editor, int count)
                 close(write_pipe[0]);
                 close(read_pipe[1]);
 
-                std::string content = editor.buffer().string(sel.begin(), sel.end());
+                String content = editor.buffer().string(sel.begin(), sel.end());
                 write(write_pipe[1], content.c_str(), content.size());
                 close(write_pipe[1]);
 
-                std::string new_content;
+                String new_content;
                 char buffer[1024];
                 while (size_t size = read(read_pipe[0], buffer, 1024))
                 {
-                    new_content += std::string(buffer, buffer+size);
+                    new_content += String(buffer, buffer+size);
                 }
                 close(read_pipe[0]);
                 waitpid(pid, NULL, 0);
@@ -626,7 +627,7 @@ void do_search(Editor& editor)
 {
     try
     {
-        std::string ex = prompt("/");
+        String ex = prompt("/");
         if (ex.empty())
             ex = RegisterManager::instance()['/'].get();
         else
@@ -640,7 +641,7 @@ void do_search(Editor& editor)
 template<bool append>
 void do_search_next(Editor& editor)
 {
-    const std::string& ex = RegisterManager::instance()['/'].get();
+    const String& ex = RegisterManager::instance()['/'].get();
     if (not ex.empty())
         editor.select(std::bind(select_next_match, _1, ex), append);
     else
@@ -688,7 +689,7 @@ void do_select_regex(Editor& editor, int count)
 {
     try
     {
-        std::string ex = prompt("select: ");
+        String ex = prompt("select: ");
         editor.multi_select(std::bind(select_all_matches, _1, ex));
     }
     catch (prompt_aborted&) {}
@@ -698,7 +699,7 @@ void do_split_regex(Editor& editor, int count)
 {
     try
     {
-        std::string ex = prompt("split: ");
+        String ex = prompt("split: ");
         editor.multi_select(std::bind(split_selection, _1, ex));
     }
     catch (prompt_aborted&) {}
@@ -842,8 +843,8 @@ public:
     { RegisterManager::instance()[m_name] = m_save; }
 
 private:
-    std::vector<std::string> m_save;
-    char                     m_name;
+    std::vector<String> m_save;
+    char                m_name;
 };
 
 void exec_keys(const KeyList& keys,
@@ -859,14 +860,14 @@ void exec_keys(const KeyList& keys,
 
     size_t pos = 0;
 
-    prompt_func = [&](const std::string&, Completer) {
+    prompt_func = [&](const String&, Completer) {
         size_t begin = pos;
         while (pos < keys.size() and keys[pos].key != '\n')
             ++pos;
 
-        std::string result;
+        String result;
         for (size_t i = begin; i < pos; ++i)
-            result += keys[i].key;
+            result += String() + keys[i].key;
         ++pos;
 
         return result;
@@ -957,14 +958,14 @@ int main(int argc, char* argv[])
     command_manager.register_commands({ "agh", "addgrouphl" }, add_group_highlighter,
                                      CommandManager::None,
                                      PerArgumentCommandCompleter({
-                                         [&](const std::string& prefix, size_t cursor_pos)
+                                         [&](const String& prefix, size_t cursor_pos)
                                          { return main_context.window().highlighters().complete_group_id(prefix, cursor_pos); },
                                          std::bind(&HighlighterRegistry::complete_highlighter, &highlighter_registry, _1, _2)
                                      }));
     command_manager.register_commands({ "rh", "rmhl" }, rm_highlighter,
                                      CommandManager::None,
                                      PerArgumentCommandCompleter({
-                                         [&](const std::string& prefix, size_t cursor_pos)
+                                         [&](const String& prefix, size_t cursor_pos)
                                          { return main_context.window().highlighters().complete_group_id(prefix, cursor_pos); }
                                      }));
     command_manager.register_commands({ "rgh", "rmgrouphl" }, rm_group_highlighter,
@@ -972,8 +973,8 @@ int main(int argc, char* argv[])
                                      [&](const CommandParameters& params, size_t token_to_complete, size_t pos_in_token)
                                      {
                                          Window& w = main_context.window();
-                                         const std::string& arg = token_to_complete < params.size() ?
-                                                                  params[token_to_complete] : std::string();
+                                         const String& arg = token_to_complete < params.size() ?
+                                                                  params[token_to_complete] : String();
                                          if (token_to_complete == 0)
                                              return w.highlighters().complete_group_id(arg, pos_in_token);
                                          else if (token_to_complete == 1)
@@ -987,7 +988,7 @@ int main(int argc, char* argv[])
     command_manager.register_commands({ "rf", "rmfilter" }, rm_filter,
                                      CommandManager::None,
                                      PerArgumentCommandCompleter({
-                                         [&](const std::string& prefix, size_t cursor_pos)
+                                         [&](const String& prefix, size_t cursor_pos)
                                          { return main_context.window().complete_filterid(prefix, cursor_pos); }
                                      }));
     command_manager.register_command("hook", add_hook, CommandManager::IgnoreSemiColons | CommandManager::DeferredShellEval);
@@ -1006,7 +1007,7 @@ int main(int argc, char* argv[])
                                      [&](const CommandParameters& params, const Context&) { set_option(option_manager, params); },
                                      CommandManager::None,
                                      PerArgumentCommandCompleter({
-                                         [&](const std::string& prefix, size_t cursor_pos)
+                                         [&](const String& prefix, size_t cursor_pos)
                                          { return option_manager.complete_option_name(prefix, cursor_pos); }
                                      }));
     command_manager.register_commands({ "setb", "setbuffer" },
@@ -1014,7 +1015,7 @@ int main(int argc, char* argv[])
                                      { set_option(context.buffer().option_manager(), params); },
                                      CommandManager::None,
                                      PerArgumentCommandCompleter({
-                                         [&](const std::string& prefix, size_t cursor_pos)
+                                         [&](const String& prefix, size_t cursor_pos)
                                          { return main_context.buffer().option_manager().complete_option_name(prefix, cursor_pos); }
                                      }));
     command_manager.register_commands({ "setw", "setwindow" },
@@ -1022,7 +1023,7 @@ int main(int argc, char* argv[])
                                      { set_option(context.window().option_manager(), params); },
                                      CommandManager::None,
                                      PerArgumentCommandCompleter({
-                                         [&](const std::string& prefix, size_t cursor_pos)
+                                         [&](const String& prefix, size_t cursor_pos)
                                          { return main_context.window().option_manager().complete_option_name(prefix, cursor_pos); }
                                      }));
 
@@ -1041,6 +1042,7 @@ int main(int argc, char* argv[])
     try
     {
         write_debug("*** This is the debug buffer, where debug info will be written ***\n");
+        write_debug("utf-8 test: é á ï");
 
         auto buffer = (argc > 1) ? open_or_create(argv[1]) : new Buffer("*scratch*", Buffer::Type::Scratch);
         main_context = Context(*buffer->get_or_create_window());
diff --git a/src/memoryview.hh b/src/memoryview.hh
index 9ca0da30..d8e509d5 100644
--- a/src/memoryview.hh
+++ b/src/memoryview.hh
@@ -35,6 +35,7 @@ public:
     memoryview(const std::initializer_list<T>& v)
         : m_pointer(v.begin()), m_size(v.size()) {}
 
+    const T* pointer() const { return m_pointer; }
     size_t size() const { return m_size; }
     const T& operator[](size_t n) const { return *(m_pointer + n); }
 
diff --git a/src/ncurses.cc b/src/ncurses.cc
index 9f7f9b5e..177530b7 100644
--- a/src/ncurses.cc
+++ b/src/ncurses.cc
@@ -82,7 +82,7 @@ void draw_window(Window& window)
     for (const DisplayAtom& atom : window.display_buffer())
     {
         assert(position == atom.coord());
-        const std::string content = atom.content();
+        const String content = atom.content();
 
         set_attribute(A_UNDERLINE, atom.attribute() & Underline);
         set_attribute(A_REVERSE, atom.attribute() & Reverse);
@@ -91,17 +91,16 @@ void draw_window(Window& window)
 
         set_color(atom.fg_color(), atom.bg_color());
 
-        size_t pos = 0;
-        size_t end;
+        auto pos = content.begin();
         while (true)
         {
             move(position.line, position.column);
             clrtoeol();
-            end = content.find_first_of('\n', pos);
-            std::string line = content.substr(pos, end - pos);
+            auto end = std::find(pos, content.end(), '\n');
+            String line(pos, end);
             addstr(line.c_str());
 
-            if (end != std::string::npos)
+            if (end != content.end())
             {
                 addch(' ');
                 position.line = position.line + 1;
@@ -134,7 +133,7 @@ void draw_window(Window& window)
     }
 
     set_color(Color::Cyan, Color::Black);
-    std::string status_line = window.status_line();
+    String status_line = window.status_line();
     static int last_status_length = 0;
     move(max_y, max_x - last_status_length);
     clrtoeol();
@@ -167,7 +166,7 @@ static Key get_key()
     return Key(modifiers, c);
 }
 
-static std::string prompt(const std::string& text, Completer completer)
+static String prompt(const String& text, Completer completer)
 {
     curs_set(2);
     auto restore_cursor = on_scope_end([]() { curs_set(0); });
@@ -182,13 +181,13 @@ static std::string prompt(const std::string& text, Completer completer)
 
     Completions completions;
     int current_completion = -1;
-    std::string text_before_completion;
+    String text_before_completion;
 
-    std::string result;
-    std::string saved_result;
+    String result;
+    String saved_result;
 
-    static std::unordered_map<std::string, std::vector<std::string>> history_per_prompt;
-    std::vector<std::string>& history = history_per_prompt[text];
+    static std::unordered_map<String, std::vector<String>> history_per_prompt;
+    std::vector<String>& history = history_per_prompt[text];
     auto history_it = history.end();
 
     while (true)
@@ -198,7 +197,7 @@ static std::string prompt(const std::string& text, Completer completer)
         {
         case '\r':
         {
-            std::vector<std::string>::iterator it;
+            std::vector<String>::iterator it;
             while ((it = find(history, result)) != history.end())
                 history.erase(it);
 
@@ -238,7 +237,7 @@ static std::string prompt(const std::string& text, Completer completer)
             if (cursor_pos != 0)
             {
                 result = result.substr(0, cursor_pos - 1)
-                       + result.substr(cursor_pos, std::string::npos);
+                       + result.substr(cursor_pos, String::npos);
 
                 --cursor_pos;
             }
@@ -248,9 +247,9 @@ static std::string prompt(const std::string& text, Completer completer)
         case CTRL('r'):
             {
                 c = getch();
-                std::string reg = RegisterManager::instance()[c].get();
+                String reg = RegisterManager::instance()[c].get();
                 current_completion = -1;
-                result = result.substr(0, cursor_pos) + reg + result.substr(cursor_pos, std::string::npos);
+                result = result.substr(0, cursor_pos) + reg + result.substr(cursor_pos, String::npos);
                 cursor_pos += reg.length();
             }
             break;
@@ -269,7 +268,7 @@ static std::string prompt(const std::string& text, Completer completer)
             }
             ++current_completion;
 
-            std::string completion;
+            String completion;
             if (current_completion >= completions.candidates.size())
             {
                 if (current_completion == completions.candidates.size() and
@@ -291,7 +290,7 @@ static std::string prompt(const std::string& text, Completer completer)
         }
         default:
             current_completion = -1;
-            result = result.substr(0, cursor_pos) + (char)c + result.substr(cursor_pos, std::string::npos);
+            result = result.substr(0, cursor_pos) + (char)c + result.substr(cursor_pos, String::npos);
             ++cursor_pos;
         }
 
@@ -304,7 +303,7 @@ static std::string prompt(const std::string& text, Completer completer)
     return result;
 }
 
-void print_status(const std::string& status)
+void print_status(const String& status)
 {
     int x,y;
     getmaxyx(stdscr, y, x);
@@ -315,6 +314,7 @@ void print_status(const std::string& status)
 
 void init(PromptFunc& prompt_func, GetKeyFunc& get_key_func)
 {
+    // setlocale(LC_ALL, "");
     initscr();
     cbreak();
     noecho();
diff --git a/src/ncurses.hh b/src/ncurses.hh
index d431fac7..a262f6a2 100644
--- a/src/ncurses.hh
+++ b/src/ncurses.hh
@@ -11,7 +11,7 @@ namespace Kakoune
 
 class Window;
 
-typedef std::function<std::string (const std::string&, Completer)> PromptFunc;
+typedef std::function<String (const String&, Completer)> PromptFunc;
 typedef std::function<Key ()> GetKeyFunc;
 
 struct prompt_aborted {};
@@ -22,7 +22,7 @@ namespace NCurses
 void init(PromptFunc& prompt_func, GetKeyFunc& get_key_func);
 void deinit();
 void draw_window(Window& window);
-void print_status(const std::string& status);
+void print_status(const String& status);
 
 }
 
diff --git a/src/option_manager.cc b/src/option_manager.cc
index 45ebdfc8..ee329d89 100644
--- a/src/option_manager.cc
+++ b/src/option_manager.cc
@@ -5,14 +5,14 @@
 namespace Kakoune
 {
 
-std::string int_to_str(int value)
+String int_to_str(int value)
 {
     std::ostringstream oss;
     oss << value;
     return oss.str();
 }
 
-Option& OptionManager::operator[] (const std::string& name)
+Option& OptionManager::operator[] (const String& name)
 {
     auto it = m_options.find(name);
     if (it != m_options.end())
@@ -23,7 +23,7 @@ Option& OptionManager::operator[] (const std::string& name)
         return m_options[name];
 }
 
-const Option& OptionManager::operator[] (const std::string& name) const
+const Option& OptionManager::operator[] (const String& name) const
 {
     auto it = m_options.find(name);
     if (it != m_options.end())
@@ -34,10 +34,10 @@ const Option& OptionManager::operator[] (const std::string& name) const
         throw option_not_found(name);
 }
 
-CandidateList OptionManager::complete_option_name(const std::string& prefix,
+CandidateList OptionManager::complete_option_name(const String& prefix,
                                                   size_t cursor_pos)
 {
-    std::string real_prefix = prefix.substr(0, cursor_pos);
+    String real_prefix = prefix.substr(0, cursor_pos);
     CandidateList result;
     if (m_parent)
         result = m_parent->complete_option_name(prefix, cursor_pos);
diff --git a/src/option_manager.hh b/src/option_manager.hh
index ca1bcd66..4309abed 100644
--- a/src/option_manager.hh
+++ b/src/option_manager.hh
@@ -12,26 +12,26 @@ namespace Kakoune
 
 struct option_not_found : public runtime_error
 {
-    option_not_found(const std::string& name)
+    option_not_found(const String& name)
         : runtime_error("option not found: " + name) {}
 };
 
-std::string int_to_str(int value);
+String int_to_str(int value);
 
 class Option
 {
 public:
     Option() {}
     explicit Option(int value) : m_value(int_to_str(value)) {}
-    explicit Option(const std::string& value) : m_value(value) {}
+    explicit Option(const String& value) : m_value(value) {}
 
     Option& operator=(int value) { m_value = int_to_str(value); return *this; }
-    Option& operator=(const std::string& value) { m_value = value; return *this; }
+    Option& operator=(const String& value) { m_value = value; return *this; }
 
     operator int() const { return atoi(m_value.c_str()); }
-    operator std::string() const { return m_value; }
+    operator String() const { return m_value; }
 private:
-    std::string m_value;
+    String m_value;
 };
 
 class OptionManager
@@ -40,10 +40,10 @@ public:
     OptionManager(OptionManager& parent)
         : m_parent(&parent) {}
 
-    Option& operator[] (const std::string& name);
-    const Option& operator[] (const std::string& name) const;
+    Option& operator[] (const String& name);
+    const Option& operator[] (const String& name) const;
 
-    CandidateList complete_option_name(const std::string& prefix,
+    CandidateList complete_option_name(const String& prefix,
                                        size_t cursor_pos);
 
 private:
@@ -52,7 +52,7 @@ private:
     // the only one allowed to construct a root option manager
     friend class GlobalOptionManager;
 
-    std::unordered_map<std::string, Option> m_options;
+    std::unordered_map<String, Option> m_options;
     OptionManager* m_parent;
 };
 
diff --git a/src/regex.hh b/src/regex.hh
new file mode 100644
index 00000000..0ad93a1b
--- /dev/null
+++ b/src/regex.hh
@@ -0,0 +1,17 @@
+#ifndef regex_hh_INCLUDED
+#define regex_hh_INCLUDED
+
+#include "string.hh"
+
+#include <boost/regex.hpp>
+
+namespace Kakoune
+{
+
+typedef boost::regex_iterator<BufferIterator> RegexIterator;
+typedef boost::basic_regex<Character> Regex;
+
+}
+
+#endif // regex_hh_INCLUDED
+
diff --git a/src/register.cc b/src/register.cc
index 79ded472..d8c48704 100644
--- a/src/register.cc
+++ b/src/register.cc
@@ -3,22 +3,22 @@
 namespace Kakoune
 {
 
-const std::string Register::ms_empty;
+const String Register::ms_empty;
 
-Register& Register::operator=(const std::string& value)
+Register& Register::operator=(const String& value)
 {
     m_content.clear();
     m_content.push_back(value);
     return *this;
 }
 
-Register& Register::operator=(const memoryview<std::string>& values)
+Register& Register::operator=(const memoryview<String>& values)
 {
-    m_content = std::vector<std::string>(values.begin(), values.end());
+    m_content = std::vector<String>(values.begin(), values.end());
     return *this;
 }
 
-const std::string& Register::get() const
+const String& Register::get() const
 {
     if (m_content.size() != 0)
         return m_content.front();
@@ -26,7 +26,7 @@ const std::string& Register::get() const
         return ms_empty;
 }
 
-const std::string& Register::get(size_t index) const
+const String& Register::get(size_t index) const
 {
     if (m_content.size() > index)
         return m_content[index];
diff --git a/src/register.hh b/src/register.hh
index 75f88354..0dc072f7 100644
--- a/src/register.hh
+++ b/src/register.hh
@@ -1,9 +1,9 @@
 #ifndef register_hh_INCLUDED
 #define register_hh_INCLUDED
 
-#include <string>
 #include <vector>
 
+#include "string.hh"
 #include "memoryview.hh"
 
 namespace Kakoune
@@ -12,20 +12,20 @@ namespace Kakoune
 class Register
 {
 public:
-    Register& operator=(const std::string& value);
-    Register& operator=(const memoryview<std::string>& values);
+    Register& operator=(const String& value);
+    Register& operator=(const memoryview<String>& values);
 
-    const std::string& get() const;
-    const std::string& get(size_t index) const;
+    const String& get() const;
+    const String& get(size_t index) const;
 
-    operator memoryview<std::string>() const
-    { return memoryview<std::string>(m_content); }
+    operator memoryview<String>() const
+    { return memoryview<String>(m_content); }
 
-    const std::vector<std::string>& content() const { return m_content; }
+    const std::vector<String>& content() const { return m_content; }
 private:
-    std::vector<std::string> m_content;
+    std::vector<String> m_content;
 
-    static const std::string ms_empty;
+    static const String ms_empty;
 };
 
 }
diff --git a/src/selectors.cc b/src/selectors.cc
index bcad49a4..c327edfd 100644
--- a/src/selectors.cc
+++ b/src/selectors.cc
@@ -1,6 +1,7 @@
 #include "selectors.hh"
 
-#include <boost/regex.hpp>
+#include "regex.hh"
+
 #include <algorithm>
 
 namespace Kakoune
@@ -371,7 +372,7 @@ SelectionAndCaptures select_whole_buffer(const Selection& selection)
 }
 
 SelectionAndCaptures select_next_match(const Selection& selection,
-                                       const std::string& regex)
+                                       const String& regex)
 {
     try
     {
@@ -379,7 +380,7 @@ SelectionAndCaptures select_next_match(const Selection& selection,
         BufferIterator end = begin;
         CaptureList captures;
 
-        boost::regex ex(regex);
+        Regex ex(regex.begin(), regex.end());
         boost::match_results<BufferIterator> matches;
 
         if (boost::regex_search(begin+1, begin.buffer().end(),
@@ -387,16 +388,16 @@ SelectionAndCaptures select_next_match(const Selection& selection,
         {
             begin = matches[0].first;
             end   = matches[0].second;
-            std::copy(matches.begin(), matches.end(),
-                      std::back_inserter(captures));
+            for (auto& match : matches)
+                captures.push_back(String(match.first, match.second));
         }
         else if (boost::regex_search(begin.buffer().begin(), begin+1,
                                      matches, ex))
         {
             begin = matches[0].first;
             end   = matches[0].second;
-            std::copy(matches.begin(), matches.end(),
-                      std::back_inserter(captures));
+            for (auto& match : matches)
+                captures.push_back(String(match.first, match.second));
         }
         if (begin == end)
             ++end;
@@ -405,18 +406,16 @@ SelectionAndCaptures select_next_match(const Selection& selection,
     }
     catch (boost::regex_error& err)
     {
-        throw runtime_error(std::string("regex error: ") + err.what());
+        throw runtime_error(String("regex error: ") + err.what());
     }
 }
 
-typedef boost::regex_iterator<BufferIterator> RegexIterator;
-
 SelectionAndCapturesList select_all_matches(const Selection& selection,
-                                            const std::string& regex)
+                                            const String& regex)
 {
     try
     {
-        boost::regex ex(regex);
+        Regex ex(regex.begin(), regex.end());
         RegexIterator re_it(selection.begin(), selection.end(), ex);
         RegexIterator re_end;
 
@@ -426,7 +425,9 @@ SelectionAndCapturesList select_all_matches(const Selection& selection,
             BufferIterator begin = (*re_it)[0].first;
             BufferIterator end   = (*re_it)[0].second;
 
-            CaptureList captures(re_it->begin(), re_it->end());
+            CaptureList captures;
+            for (auto& match : *re_it)
+                captures.push_back(String(match.first, match.second));
 
             result.push_back(SelectionAndCaptures(begin,
                                                   begin == end ? end : end-1,
@@ -436,16 +437,16 @@ SelectionAndCapturesList select_all_matches(const Selection& selection,
     }
     catch (boost::regex_error& err)
     {
-        throw runtime_error(std::string("regex error: ") + err.what());
+        throw runtime_error(String("regex error: ") + err.what());
     }
 }
 
 SelectionAndCapturesList split_selection(const Selection& selection,
-                                         const std::string& separator_regex)
+                                         const String& separator_regex)
 {
     try
     {
-        boost::regex ex(separator_regex);
+        Regex ex(separator_regex.begin(), separator_regex.end());
         RegexIterator re_it(selection.begin(), selection.end(), ex,
                             boost::regex_constants::match_nosubs);
         RegexIterator re_end;
@@ -464,7 +465,7 @@ SelectionAndCapturesList split_selection(const Selection& selection,
     }
     catch (boost::regex_error& err)
     {
-        throw runtime_error(std::string("regex error: ") + err.what());
+        throw runtime_error(String("regex error: ") + err.what());
     }
 }
 
diff --git a/src/selectors.hh b/src/selectors.hh
index c1d24e88..b9acd08e 100644
--- a/src/selectors.hh
+++ b/src/selectors.hh
@@ -33,13 +33,13 @@ SelectionAndCaptures select_whole_lines(const Selection& selection);
 SelectionAndCaptures select_whole_buffer(const Selection& selection);
 
 SelectionAndCaptures select_next_match(const Selection& selection,
-                                       const std::string& regex);
+                                       const String& regex);
 
 SelectionAndCapturesList select_all_matches(const Selection& selection,
-                                            const std::string& regex);
+                                            const String& regex);
 
 SelectionAndCapturesList split_selection(const Selection& selection,
-                                         const std::string& separator_regex);
+                                         const String& separator_regex);
 
 }
 
diff --git a/src/string.hh b/src/string.hh
new file mode 100644
index 00000000..38a8aaae
--- /dev/null
+++ b/src/string.hh
@@ -0,0 +1,16 @@
+#ifndef string_hh_INCLUDED
+#define string_hh_INCLUDED
+
+#include <string>
+
+namespace Kakoune
+{
+
+typedef char Character;
+typedef std::string String;
+
+}
+
+
+#endif // string_hh_INCLUDED
+
diff --git a/src/utils.hh b/src/utils.hh
index 9e9aa453..32e593b8 100644
--- a/src/utils.hh
+++ b/src/utils.hh
@@ -112,7 +112,7 @@ bool contains(const Container& container, const T& value)
     return find(container, value) != container.end();
 }
 
-inline std::string str_to_str(const std::string& str)
+inline String str_to_str(const String& str)
 {
     return str;
 }
diff --git a/src/window.cc b/src/window.cc
index 84503ca4..91e9baa4 100644
--- a/src/window.cc
+++ b/src/window.cc
@@ -113,7 +113,7 @@ void Window::scroll_to_keep_cursor_visible_ifn()
     }
 }
 
-std::string Window::status_line() const
+String Window::status_line() const
 {
     BufferCoord cursor = buffer().line_and_column_at(selections().back().last());
     std::ostringstream oss;
diff --git a/src/window.hh b/src/window.hh
index 7e77c6ee..66264c89 100644
--- a/src/window.hh
+++ b/src/window.hh
@@ -35,7 +35,7 @@ public:
 
     void update_display_buffer();
 
-    std::string status_line() const;
+    String status_line() const;
 
     HighlighterGroup& highlighters() { return m_highlighters; }