Refactor String, use a common StringOps interface, hide std::string

24 files changed, 232 insertions, 253 deletions

diff --git a/src/buffer_utils.cc b/src/buffer_utils.cc
index 88f7d4f8..eda4d9d4 100644
--- a/src/buffer_utils.cc
+++ b/src/buffer_utils.cc
@@ -53,7 +53,7 @@ Buffer* create_buffer_from_data(StringView data, StringView name,
 
     const char* pos = data.begin();
     if (data.length() >= 3 and
-       data[0] == '\xEF' and data[1] == '\xBB' and data[2] == '\xBF')
+       data[0_byte] == '\xEF' and data[1_byte] == '\xBB' and data[2_byte] == '\xBF')
     {
         bom = true;
         pos = data.begin() + 3;
@@ -81,7 +81,7 @@ Buffer* create_buffer_from_data(StringView data, StringView name,
     if (buffer)
         buffer->reload(std::move(lines), fs_timestamp);
     else
-        buffer = new Buffer{name, flags, std::move(lines), fs_timestamp};
+        buffer = new Buffer{name.str(), flags, std::move(lines), fs_timestamp};
 
     OptionManager& options = buffer->options();
     options.get_local_option("eolformat").set<String>(crlf ? "crlf" : "lf");
diff --git a/src/client.cc b/src/client.cc
index 74a9aff2..ae18ebe4 100644
--- a/src/client.cc
+++ b/src/client.cc
@@ -257,6 +257,11 @@ StringView Client::get_env_var(const String& name) const
     return it->second;
 }
 
+StringView Client::get_env_var(StringView name) const
+{
+    return get_env_var(name.str());
+}
+
 void Client::on_option_changed(const Option& option)
 {
     if (option.name() == "ui_options")
diff --git a/src/client.hh b/src/client.hh
index 0f7eeb40..8a8c309f 100644
--- a/src/client.hh
+++ b/src/client.hh
@@ -51,6 +51,7 @@ public:
     void change_buffer(Buffer& buffer);
 
     StringView get_env_var(const String& name) const;
+    StringView get_env_var(StringView name) const;
 
 private:
     void on_option_changed(const Option& option) override;
diff --git a/src/command_manager.cc b/src/command_manager.cc
index 67e33c1e..459fcc22 100644
--- a/src/command_manager.cc
+++ b/src/command_manager.cc
@@ -119,7 +119,7 @@ String get_until_delimiter(StringView base, ByteCount& pos,
         }
         ++pos;
     }
-    return base.substr(start, pos - start);
+    return base.substr(start, pos - start).str();
 }
 
 struct unknown_expand : parse_error
@@ -313,7 +313,7 @@ String eval_token(const Token& token, Context& context,
         return ShellManager::instance().eval(content, context, shell_params,
                                              env_vars);
     case Token::Type::RegisterExpand:
-        return context.main_sel_register_value(content);
+        return context.main_sel_register_value(content).str();
     case Token::Type::OptionExpand:
         return context.options()[content].get_as_string();
     case Token::Type::ValExpand:
diff --git a/src/commands.cc b/src/commands.cc
index 08a9e3a6..97e19bd8 100644
--- a/src/commands.cc
+++ b/src/commands.cc
@@ -47,7 +47,7 @@ Buffer* open_fifo(StringView name, StringView filename, bool scroll)
     if (fd < 0)
        throw runtime_error("unable to open " + filename);
 
-    return create_fifo_buffer(name, fd, scroll);
+    return create_fifo_buffer(name.str(), fd, scroll);
 }
 
 const PerArgumentCommandCompleter filename_completer({
@@ -69,9 +69,9 @@ static CandidateList complete_buffer_name(StringView prefix, ByteCount cursor_po
         StringView match_name = name;
         if (not include_dirs and buffer->flags() & Buffer::Flags::File)
         {
-            ByteCount pos = name.find_last_of('/');
-            if (pos != (int)String::npos)
-                match_name = name.substr(pos+1);
+            auto it = find(reversed(name), '/');
+            if (it != name.rend())
+                match_name = StringView{it.base() + 2, name.end()};
         }
         if (prefix_match(match_name, prefix))
             prefix_result.push_back(name);
@@ -434,7 +434,7 @@ const CommandDesc namebuf_cmd = {
 Completions complete_highlighter(const Context& context,
                                  StringView arg, ByteCount pos_in_token, bool only_group)
 {
-    const bool shared = not arg.empty() and arg[0] == '/';
+    const bool shared = not arg.empty() and arg[0_byte] == '/';
     if (shared)
     {
         auto& group = DefinedHighlighters::instance();
@@ -480,7 +480,7 @@ Highlighter& get_highlighter(const Context& context, StringView path)
         throw runtime_error("group path should not be empty");
 
     Highlighter* root = nullptr;
-    if (path[0] == '/')
+    if (path[0_byte] == '/')
     {
         root = &DefinedHighlighters::instance();
         path = path.substr(1_byte);
@@ -603,12 +603,12 @@ const CommandDesc add_hook_cmd = {
 
             if (regex_match(param.begin(), param.end(), regex))
                 CommandManager::instance().execute(command, context, {},
-                                                   { { "hook_param", param } });
+                                                   { { "hook_param", param.str() } });
         };
         StringView group;
         if (parser.has_option("group"))
             group = parser.option_value("group");
-        get_scope(parser[0], context).hooks().add_hook(parser[1], group, hook_func);
+        get_scope(parser[0], context).hooks().add_hook(parser[1], group.str(), hook_func);
     }
 };
 
@@ -866,7 +866,7 @@ const CommandDesc debug_cmd = {
             {
                 size_t count = domain_allocated_bytes[domain];
                 total += count;
-                write_debug("  "_sv + domain_name((MemoryDomain)domain) + ": " + to_string(count));
+                write_debug("  "_str + domain_name((MemoryDomain)domain) + ": " + to_string(count));
             }
             write_debug("  Total: " + to_string(total));
             #if defined(__GLIBC__) || defined(__CYGWIN__)
@@ -1254,7 +1254,7 @@ const CommandDesc prompt_cmd = {
     {
         if (params[1].length() != 1)
             throw runtime_error("register name should be a single character");
-        const char reg = params[1][0];
+        const char reg = params[1][0_byte];
         const String& command = params[2];
 
         String initstr;
@@ -1267,7 +1267,7 @@ const CommandDesc prompt_cmd = {
             {
                 if (event != PromptEvent::Validate)
                     return;
-                RegisterManager::instance()[reg] = ConstArrayView<String>(str);
+                RegisterManager::instance()[reg] = ConstArrayView<String>(str.str());
 
                 CommandManager::instance().execute(command, context);
             });
@@ -1344,12 +1344,11 @@ const CommandDesc info_cmd = {
             if (parser.has_option("anchor"))
             {
                 auto anchor = parser.option_value("anchor");
-                size_t dot = anchor.find_first_of('.');
-                if (dot == String::npos)
+                auto dot = find(anchor, '.');
+                if (dot == anchor.end())
                     throw runtime_error("expected <line>.<column> for anchor");
-                ByteCount dotb = (int)dot;
-                ByteCoord coord{str_to_int(anchor.substr(0, dotb))-1,
-                                str_to_int(anchor.substr(dotb+1))-1};
+                ByteCoord coord{str_to_int({anchor.begin(), dot})-1,
+                                str_to_int({dot+1, anchor.end()})-1};
                 pos = context.window().display_position(coord);
                 style = InfoStyle::Inline;
                 if (parser.has_option("placement"))
diff --git a/src/display_buffer.cc b/src/display_buffer.cc
index a56fe612..3bcf37b2 100644
--- a/src/display_buffer.cc
+++ b/src/display_buffer.cc
@@ -49,7 +49,7 @@ void DisplayAtom::trim_begin(CharCount count)
         m_begin = utf8::advance(m_buffer->iterator_at(m_begin),
                                 m_buffer->iterator_at(m_end), count).coord();
     else
-        m_text = m_text.substr(count);
+        m_text = m_text.substr(count).str();
     check_invariant();
 }
 
@@ -59,7 +59,7 @@ void DisplayAtom::trim_end(CharCount count)
         m_end = utf8::advance(m_buffer->iterator_at(m_end),
                               m_buffer->iterator_at(m_begin), -count).coord();
     else
-        m_text = m_text.substr(0, m_text.char_length() - count);
+        m_text = m_text.substr(0, m_text.char_length() - count).str();
     check_invariant();
 }
 
diff --git a/src/file.cc b/src/file.cc
index a12b40ce..ec409df8 100644
--- a/src/file.cc
+++ b/src/file.cc
@@ -26,8 +26,8 @@ namespace Kakoune
 
 String parse_filename(StringView filename)
 {
-    if (filename.length() >= 1 and filename[0] == '~' and
-        (filename.length() == 1 or filename[1] == '/'))
+    if (filename.length() >= 1 and filename[0_byte] == '~' and
+        (filename.length() == 1 or filename[1_byte] == '/'))
         return parse_filename("$HOME"_str + filename.substr(1_byte));
 
     ByteCount pos = 0;
@@ -90,7 +90,7 @@ String real_path(StringView filename)
 
         auto it = find(existing.rbegin(), existing.rend(), '/');
         if (it == existing.rend())
-            return filename;
+            return filename.str();
 
         existing = StringView{existing.begin(), it.base()-1};
         non_existing = StringView{it.base(), filename.end()};
@@ -105,7 +105,7 @@ String compact_path(StringView filename)
     getcwd(cwd, 1024);
     String real_cwd = real_path(cwd) + "/";
     if (prefix_match(real_filename, real_cwd))
-        return real_filename.substr(real_cwd.length());
+        return real_filename.substr(real_cwd.length()).str();
 
     const char* home = getenv("HOME");
     if (home)
@@ -258,14 +258,14 @@ void write_buffer_to_backup_file(Buffer& buffer)
 String find_file(StringView filename, ConstArrayView<String> paths)
 {
     struct stat buf;
-    if (filename.length() > 1 and filename[0] == '/')
+    if (filename.length() > 1 and filename[0_byte] == '/')
     {
         if (stat(filename.zstr(), &buf) == 0 and S_ISREG(buf.st_mode))
             return filename.str();
          return "";
     }
     if (filename.length() > 2 and
-             filename[0] == '~' and filename[1] == '/')
+             filename[0_byte] == '~' and filename[1_byte] == '/')
     {
         String candidate = getenv("HOME") + filename.substr(1_byte).str();
         if (stat(candidate.c_str(), &buf) == 0 and S_ISREG(buf.st_mode))
@@ -386,7 +386,7 @@ Vector<String> complete_command(StringView prefix, ByteCount cursor_pos)
     Vector<String> res;
     for (auto dir : split(getenv("PATH"), ':'))
     {
-        String dirname = dir;
+        String dirname = dir.str();
         if (not dirname.empty() and dirname.back() != '/')
             dirname += '/';
 
diff --git a/src/highlighters.cc b/src/highlighters.cc
index 3cd00a75..900835cf 100644
--- a/src/highlighters.cc
+++ b/src/highlighters.cc
@@ -264,9 +264,9 @@ public:
                 if (not regex_match(it->begin(), it->end(), res, face_spec_ex))
                     throw runtime_error("wrong face spec: '" + *it +
                                          "' expected <capture>:<facespec>");
-                get_face(res[2].str()); // throw if wrong face spec
-                int capture = str_to_int(res[1].str());
-                faces.emplace_back(capture, res[2].str());
+                get_face({res[2].first, res[2].second}); // throw if wrong face spec
+                int capture = str_to_int({res[1].first, res[1].second});
+                faces.emplace_back(capture, String{res[2].first, res[2].second});
             }
 
             String id = "hlregex'" + params[0] + "'";
@@ -711,7 +711,8 @@ void expand_unprintable(const Context& context, HighlightFlags flags, DisplayBuf
                     {
                         std::ostringstream oss;
                         oss << "U+" << std::hex << cp;
-                        String str = oss.str();
+                        const auto& stdstr = oss.str();
+                        String str{stdstr.begin(), stdstr.end()};
                         if (it.coord() != atom_it->begin())
                             atom_it = ++line.split(atom_it, it.coord());
                         if (next.coord() < atom_it->end())
diff --git a/src/hook_manager.cc b/src/hook_manager.cc
index cc4c1ec6..d7879c61 100644
--- a/src/hook_manager.cc
+++ b/src/hook_manager.cc
@@ -51,7 +51,7 @@ void HookManager::run_hook(StringView hook_name,
     for (auto& hook : hook_list_it->second)
     {
         if (not hook.first.empty() and not disabled_hooks.empty() and
-            regex_match(hook.first, disabled_hooks))
+            regex_match(hook.first.begin(), hook.first.end(), disabled_hooks))
             continue;
 
         try
diff --git a/src/id_map.hh b/src/id_map.hh
index e6f2f7b0..72d1c2f0 100644
--- a/src/id_map.hh
+++ b/src/id_map.hh
@@ -65,7 +65,7 @@ public:
         if (it != m_content.end())
             return it->second;
 
-        append({ id, Value{} });
+        append({ id.str(), Value{} });
         return (m_content.end()-1)->second;
     }
 
diff --git a/src/input_handler.cc b/src/input_handler.cc
index 23717f88..1e6d0cad 100644
--- a/src/input_handler.cc
+++ b/src/input_handler.cc
@@ -154,7 +154,7 @@ public:
         if (m_params.reg != '"')
         {
             atoms.push_back({ "; reg=", Face(Colors::Yellow) });
-            atoms.push_back({ StringView(m_params.reg), Face(Colors::Green) });
+            atoms.push_back({ StringView(m_params.reg).str(), Face(Colors::Green) });
         }
         return atoms;
     }
@@ -325,12 +325,12 @@ public:
             m_display_pos = m_cursor_pos + 1 - width;
 
         if (m_cursor_pos == m_line.char_length())
-            return DisplayLine{{ {m_line.substr(m_display_pos, width-1), get_face("StatusLine")},
+            return DisplayLine{{ {m_line.substr(m_display_pos, width-1).str(), get_face("StatusLine")},
                                  {" "_str, get_face("StatusCursor")} }};
         else
-            return DisplayLine({ { m_line.substr(m_display_pos, m_cursor_pos - m_display_pos), get_face("StatusLine") },
-                                 { m_line.substr(m_cursor_pos,1), get_face("StatusCursor") },
-                                 { m_line.substr(m_cursor_pos+1, width - m_cursor_pos + m_display_pos - 1), get_face("StatusLine") } });
+            return DisplayLine({ { m_line.substr(m_display_pos, m_cursor_pos - m_display_pos).str(), get_face("StatusLine") },
+                                 { m_line.substr(m_cursor_pos,1).str(), get_face("StatusCursor") },
+                                 { m_line.substr(m_cursor_pos+1, width - m_cursor_pos + m_display_pos - 1).str(), get_face("StatusLine") } });
     }
 private:
     CharCount      m_cursor_pos = 0;
@@ -473,7 +473,7 @@ String common_prefix(ConstArrayView<String> strings)
         while (common_len < len and str[common_len] == res[common_len])
             ++common_len;
         if (common_len != res.length())
-            res = res.substr(0, common_len);
+            res = res.substr(0, common_len).str();
     }
     return res;
 }
@@ -484,7 +484,7 @@ public:
     Prompt(InputHandler& input_handler, StringView prompt,
            String initstr, Face face, Completer completer,
            PromptCallback callback)
-        : InputMode(input_handler), m_prompt(prompt), m_prompt_face(face),
+        : InputMode(input_handler), m_prompt(prompt.str()), m_prompt_face(face),
           m_completer(completer), m_callback(callback),
           m_autoshowcompl{context().options()["autoshowcompl"].get<bool>()}
     {
@@ -600,7 +600,7 @@ public:
                 String prefix = common_prefix(candidates);
                 if (m_completions.end - m_completions.start > prefix.length())
                     prefix = line.substr(m_completions.start,
-                                         m_completions.end - m_completions.start);
+                                         m_completions.end - m_completions.start).str();
 
                 if (not prefix.empty())
                 {
@@ -742,7 +742,7 @@ private:
         History::iterator it;
         while ((it = find(history, entry)) != history.end())
             history.erase(it);
-        history.push_back(entry);
+        history.push_back(entry.str());
     }
 };
 UnorderedMap<String, Prompt::History, MemoryDomain::History> Prompt::ms_history;
diff --git a/src/insert_completer.cc b/src/insert_completer.cc
index 45f9681f..5d76023d 100644
--- a/src/insert_completer.cc
+++ b/src/insert_completer.cc
@@ -119,7 +119,7 @@ InsertCompletion complete_word(const Buffer& buffer, ByteCoord cursor_pos)
     ComplAndDescList result;
     result.reserve(matches.size());
     for (auto& m : matches)
-        result.emplace_back(m, "");
+        result.emplace_back(m.str(), "");
 
     return { begin.coord(), cursor_pos, std::move(result), buffer.timestamp() };
 }
@@ -158,7 +158,7 @@ InsertCompletion complete_filename(const Buffer& buffer, ByteCoord cursor_pos,
             if (not dir.empty() and dir.back() != '/')
                 dir += '/';
             for (auto& filename : Kakoune::complete_filename(dir + prefix, Regex{}))
-                res.emplace_back(filename.substr(dir.length()), "");
+                res.emplace_back(filename.substr(dir.length()).str(), "");
         }
     }
     if (res.empty())
@@ -178,16 +178,17 @@ InsertCompletion complete_option(const Buffer& buffer, ByteCoord cursor_pos,
     MatchResults<String::const_iterator> match;
     if (regex_match(desc.begin(), desc.end(), match, re))
     {
-        ByteCoord coord{ str_to_int(match[1].str()) - 1, str_to_int(match[2].str()) - 1 };
+        ByteCoord coord{ str_to_int({match[1].first, match[1].second}) - 1,
+                         str_to_int({match[2].first, match[2].second}) - 1 };
         if (not buffer.is_valid(coord))
             return {};
         auto end = coord;
         if (match[3].matched)
         {
-            ByteCount len = str_to_int(match[3].str());
+            ByteCount len = str_to_int({match[3].first, match[3].second});
             end = buffer.advance(coord, len);
         }
-        size_t timestamp = (size_t)str_to_int(match[4].str());
+        size_t timestamp = (size_t)str_to_int({match[4].first, match[4].second});
         auto changes = buffer.changes_since(timestamp);
         if (find_if(changes, [&](const Buffer::Change& change){
                         return change.begin < coord;
@@ -204,7 +205,7 @@ InsertCompletion complete_option(const Buffer& buffer, ByteCoord cursor_pos,
             {
                 auto splitted = split(*it, '@');
                 if (not splitted.empty() and prefix_match(splitted[0], prefix))
-                    res.emplace_back(splitted[0], splitted.size() > 1 ? splitted[1] : "");
+                    res.emplace_back(splitted[0].str(), splitted.size() > 1 ? splitted[1].str() : "");
             }
             return { coord, end, std::move(res), timestamp };
         }
@@ -222,7 +223,7 @@ InsertCompletion complete_line(const Buffer& buffer, ByteCoord cursor_pos)
             continue;
         ByteCount len = buffer[l].length();
         if (len > cursor_pos.column and std::equal(prefix.begin(), prefix.end(), buffer[l].begin()))
-            res.emplace_back(buffer[l].substr(0_byte, len-1), "");
+            res.emplace_back(buffer[l].substr(0_byte, len-1).str(), "");
     }
     if (res.empty())
         return {};
diff --git a/src/keys.cc b/src/keys.cc
index b328252c..7dd45383 100644
--- a/src/keys.cc
+++ b/src/keys.cc
@@ -64,9 +64,9 @@ KeyList parse_keys(StringView str)
         Key::Modifiers modifier = Key::Modifiers::None;
 
         StringView desc{it.base()+1, end_it.base()};
-        if (desc.length() > 2 and desc[1] == '-')
+        if (desc.length() > 2 and desc[1_byte] == '-')
         {
-            switch(tolower(desc[0]))
+            switch(tolower(desc[0_byte]))
             {
                 case 'c': modifier = Key::Modifiers::Control; break;
                 case 'a': modifier = Key::Modifiers::Alt; break;
@@ -82,7 +82,7 @@ KeyList parse_keys(StringView str)
             result.push_back(canonicalize_ifn({ modifier, name_it->key }));
         else if (desc.char_length() == 1)
             result.push_back(Key{ modifier, desc[0_char] });
-        else if (tolower(desc[0]) == 'f' and desc.length() <= 3)
+        else if (tolower(desc[0_byte]) == 'f' and desc.length() <= 3)
         {
             int val = str_to_int(desc.substr(1_byte));
             if (val >= 1 and val <= 12)
diff --git a/src/main.cc b/src/main.cc
index af77ba44..f022361d 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -37,10 +37,10 @@ void run_unit_tests();
 String runtime_directory()
 {
     String bin_path = get_kak_binary_path();
-    size_t last_slash = bin_path.find_last_of('/');
-    if (last_slash == String::npos)
+    auto it = find(reversed(bin_path), '/');
+    if (it == bin_path.rend())
         throw runtime_error("unable to determine runtime directory");
-    return bin_path.substr(0_byte, (int)last_slash) + "/../share/kak";
+    return StringView{bin_path.begin(), it.base()-1} + "/../share/kak";
 }
 
 void register_env_vars()
@@ -54,7 +54,7 @@ void register_env_vars()
             { return context.buffer().display_name(); }
         }, {
             "buffile",
-            [](StringView name, const Context& context) -> String
+            [](StringView name, const Context& context)
             { return context.buffer().name(); }
         }, {
             "buflist",
@@ -85,19 +85,19 @@ void register_env_vars()
             { return context.options()[name.substr(4_byte)].get_as_string(); }
         }, {
             "reg_.+",
-            [](StringView name, const Context& context) -> String
-            { return context.main_sel_register_value(name.substr(4_byte)); }
+            [](StringView name, const Context& context)
+            { return context.main_sel_register_value(name.substr(4_byte)).str(); }
         }, {
             "client_env_.+",
-            [](StringView name, const Context& context) -> String
-            { return context.client().get_env_var(name.substr(11_byte)); }
+            [](StringView name, const Context& context)
+            { return context.client().get_env_var(name.substr(11_byte)).str(); }
         }, {
             "session",
-            [](StringView name, const Context& context) -> String
+            [](StringView name, const Context& context)
             { return Server::instance().session(); }
         }, {
             "client",
-            [](StringView name, const Context& context) -> String
+            [](StringView name, const Context& context)
             { return context.name(); }
         }, {
             "cursor_line",
@@ -356,7 +356,7 @@ int run_server(StringView session, StringView init_command,
 
     write_debug("*** This is the debug buffer, where debug info will be written ***");
 
-    Server server(session.empty() ? to_string(getpid()) : String{session});
+    Server server(session.empty() ? to_string(getpid()) : session.str());
 
     if (not ignore_kakrc) try
     {
@@ -385,7 +385,7 @@ int run_server(StringView session, StringView init_command,
         for (auto& file : reversed(files))
         {
             if (not create_buffer_from_file(file))
-                new Buffer(file, Buffer::Flags::New | Buffer::Flags::File);
+                new Buffer(file.str(), Buffer::Flags::New | Buffer::Flags::File);
         }
     }
     catch (Kakoune::runtime_error& error)
diff --git a/src/ncurses_ui.cc b/src/ncurses_ui.cc
index 9e401985..13de9fd2 100644
--- a/src/ncurses_ui.cc
+++ b/src/ncurses_ui.cc
@@ -591,7 +591,7 @@ void NCursesUI::menu_show(ConstArrayView<String> items,
     const CharCount maxlen = min((int)maxsize.column-2, 200);
     for (auto& item : items)
     {
-        m_items.push_back(item.substr(0_char, maxlen));
+        m_items.push_back(item.substr(0_char, maxlen).str());
         longest = max(longest, m_items.back().char_length());
     }
     longest += 1;
diff --git a/src/normal.cc b/src/normal.cc
index 8893b8f5..4d16bad0 100644
--- a/src/normal.cc
+++ b/src/normal.cc
@@ -375,7 +375,7 @@ void pipe(Context& context, NormalParams)
                 real_cmd = context.main_sel_register_value("|");
             else
             {
-                RegisterManager::instance()['|'] = String{cmdline};
+                RegisterManager::instance()['|'] = cmdline.str();
                 real_cmd = cmdline;
             }
 
@@ -397,7 +397,7 @@ void pipe(Context& context, NormalParams)
                                                         {}, EnvVarMap{});
                     if ((insert_eol or sel.max() == buffer.back_coord()) and
                         str.back() == '\n')
-                        str = str.substr(0, str.length()-1);
+                        str = str.substr(0, str.length()-1).str();
                     strings.push_back(std::move(str));
                 }
                 ScopedEdition edition(context);
@@ -428,7 +428,7 @@ void insert_output(Context& context, NormalParams)
                 real_cmd = context.main_sel_register_value("|");
             else
             {
-                RegisterManager::instance()['|'] = String{cmdline};
+                RegisterManager::instance()['|'] = cmdline.str();
                 real_cmd = cmdline;
             }
 
@@ -617,7 +617,7 @@ void search(Context& context, NormalParams)
                      if (ex.empty())
                          ex = Regex{context.main_sel_register_value("/").str()};
                      else if (event == PromptEvent::Validate)
-                         RegisterManager::instance()['/'] = String{ex.str()};
+                         RegisterManager::instance()['/'] = ex.str();
                      if (not ex.empty() and not ex.str().empty())
                          select_next_match<direction, mode>(context.buffer(), context.selections(), ex);
                  });
@@ -674,7 +674,7 @@ void select_regex(Context& context, NormalParams)
         if (ex.empty())
             ex = Regex{context.main_sel_register_value("/").str()};
         else if (event == PromptEvent::Validate)
-            RegisterManager::instance()['/'] = String{ex.str()};
+            RegisterManager::instance()['/'] = ex.str();
         if (not ex.empty() and not ex.str().empty())
             select_all_matches(context.selections(), ex);
     });
@@ -686,7 +686,7 @@ void split_regex(Context& context, NormalParams)
         if (ex.empty())
             ex = Regex{context.main_sel_register_value("/").str()};
         else if (event == PromptEvent::Validate)
-            RegisterManager::instance()['/'] = String{ex.str()};
+            RegisterManager::instance()['/'] = ex.str();
         if (not ex.empty() and not ex.str().empty())
             split_selections(context.selections(), ex);
     });
diff --git a/src/option_types.hh b/src/option_types.hh
index ef611ae4..0f204b70 100644
--- a/src/option_types.hh
+++ b/src/option_types.hh
@@ -14,8 +14,8 @@
 namespace Kakoune
 {
 
-inline String option_to_string(StringView opt) { return opt; }
-inline void option_from_string(StringView str, String& opt) { opt = str; }
+inline String option_to_string(StringView opt) { return opt.str(); }
+inline void option_from_string(StringView str, String& opt) { opt = str.str(); }
 
 inline String option_to_string(int opt) { return to_string(opt); }
 inline void option_from_string(StringView str, int& opt) { opt = str_to_int(str); }
diff --git a/src/parameters_parser.cc b/src/parameters_parser.cc
index 06c081e0..e86d7101 100644
--- a/src/parameters_parser.cc
+++ b/src/parameters_parser.cc
@@ -21,7 +21,7 @@ ParametersParser::ParametersParser(ParameterList params,
     {
         if (not only_pos and params[i] == "--")
             only_pos = true;
-        else if (not only_pos and params[i][0] == '-')
+        else if (not only_pos and params[i][0_byte] == '-')
         {
             auto it = m_desc.switches.find(params[i].substr(1_byte));
             if (it == m_desc.switches.end())
@@ -30,7 +30,7 @@ ParametersParser::ParametersParser(ParameterList params,
             if (it->second.takes_arg)
             {
                 ++i;
-                if (i == params.size() or params[i][0] == '-')
+                if (i == params.size() or params[i][0_byte] == '-')
                    throw missing_option_value(it->first);
             }
         }
@@ -51,7 +51,7 @@ bool ParametersParser::has_option(const String& name) const
     kak_assert(m_desc.switches.find(name) != m_desc.switches.end());
     for (auto& param : m_params)
     {
-        if (param[0] == '-' and param.substr(1_byte) == name)
+        if (param[0_byte] == '-' and param.substr(1_byte) == name)
             return true;
 
         if (param == "--")
@@ -70,7 +70,7 @@ const String& ParametersParser::option_value(const String& name) const
 
     for (size_t i = 0; i < m_params.size(); ++i)
     {
-        if (m_params[i][0] == '-' and m_params[i].substr(1_byte) == name)
+        if (m_params[i][0_byte] == '-' and m_params[i].substr(1_byte) == name)
             return m_params[i+1];
 
         if (m_params[i] == "--")
diff --git a/src/regex.cc b/src/regex.cc
index d2c8f615..23916036 100644
--- a/src/regex.cc
+++ b/src/regex.cc
@@ -7,7 +7,8 @@ namespace Kakoune
 
 String option_to_string(const Regex& re)
 {
-    return String{re.str()};
+    const auto& str = re.str();
+    return String{str.begin(), str.end()};
 }
 
 void option_from_string(StringView str, Regex& re)
diff --git a/src/regex.hh b/src/regex.hh
index aa71f669..8d87427e 100644
--- a/src/regex.hh
+++ b/src/regex.hh
@@ -29,15 +29,27 @@ struct Regex : std::regex
     bool operator==(const Regex& other) { return m_str == other.m_str; }
     bool operator!=(const Regex& other) { return m_str != other.m_str; }
 
-    StringView str() const { return m_str; }
+    const String& str() const { return m_str; }
 
 private:
     String m_str;
 };
 namespace regex_ns = std;
 #else
+struct Regex : boost::regex
+{
+    Regex() = default;
+
+    explicit Regex(StringView re, flag_type flags = ECMAScript)
+        : boost::regex(re.begin(), re.end(), flags) {}
+
+    template<typename Iterator>
+    Regex(Iterator begin, Iterator end, flag_type flags = ECMAScript)
+        : boost::regex(begin, end, flags) {}
+
+        String str() const { auto s = boost::regex::str(); return {s.begin(), s.end()}; }
+};
 namespace regex_ns = boost;
-using Regex = boost::regex;
 #endif
 
 template<typename Iterator>
diff --git a/src/register_manager.cc b/src/register_manager.cc
index 7a071ae3..7990c13b 100644
--- a/src/register_manager.cc
+++ b/src/register_manager.cc
@@ -59,7 +59,7 @@ private:
 Register& RegisterManager::operator[](StringView reg)
 {
     if (reg.length() == 1)
-        return (*this)[reg[0]];
+        return (*this)[reg[0_byte]];
 
     static const IdMap<Codepoint> reg_names = {
         { "slash", '/' },
diff --git a/src/shell_manager.cc b/src/shell_manager.cc
index d10c4ad5..6b82ba91 100644
--- a/src/shell_manager.cc
+++ b/src/shell_manager.cc
@@ -23,7 +23,7 @@ ShellManager::ShellManager()
         new_path = path + ":"_str;
 
     String kak_path = get_kak_binary_path();
-    StringView kak_dir = kak_path.substr(0_byte, (int)kak_path.find_last_of('/'));
+    StringView kak_dir{kak_path.begin(), find(reversed(kak_path), '/').base()-1};
     new_path += kak_dir;
     setenv("PATH", new_path.c_str(), 1);
 }
@@ -111,7 +111,7 @@ String ShellManager::pipe(StringView input,
             StringView name = StringView(match[1].first, match[1].second);
             kak_assert(name.length() > 0);
 
-            auto local_var = env_vars.find(name);
+            auto local_var = env_vars.find(name.str());
             if (local_var != env_vars.end())
                 setenv(("kak_" + name).c_str(), local_var->second.c_str(), 1);
             else
diff --git a/src/string.cc b/src/string.cc
index beeb4a74..5da03901 100644
--- a/src/string.cc
+++ b/src/string.cc
@@ -9,11 +9,6 @@
 namespace Kakoune
 {
 
-bool operator<(StringView lhs, StringView rhs)
-{
-    return std::lexicographical_compare(lhs.begin(), lhs.end(), rhs.begin(), rhs.end());
-}
-
 Vector<String> split(StringView str, char separator, char escape)
 {
     Vector<String> res;
diff --git a/src/string.hh b/src/string.hh
index 74df3fd7..4fb24c1e 100644
--- a/src/string.hh
+++ b/src/string.hh
@@ -14,56 +14,133 @@ namespace Kakoune
 
 class StringView;
 
-using StringBase = std::basic_string<char, std::char_traits<char>,
-                                     Allocator<char, MemoryDomain::String>>;
-
-constexpr ByteCount strlen(const char* s)
+template<typename Type, typename CharType>
+class StringOps
 {
-    return *s == 0 ? 0 : strlen(s+1) + 1;
-}
+public:
+    using value_type = CharType;
+
+    friend bool operator==(const Type& lhs, const Type& rhs)
+    {
+        return lhs.length() == rhs.length() and 
+           std::equal(lhs.begin(), lhs.end(), rhs.begin());
+    }
+
+    friend bool operator!=(const Type& lhs, const Type& rhs)
+    {
+        return lhs.length() != rhs.length() or 
+           not std::equal(lhs.begin(), lhs.end(), rhs.begin());
+    }
+
+    friend bool operator<(const Type& lhs, const Type& rhs)
+    {
+        return std::lexicographical_compare(lhs.begin(), lhs.end(),
+                                            rhs.begin(), rhs.end());
+    }
+
+    friend inline size_t hash_value(const Type& str)
+    {
+        return hash_data(str.data(), (int)str.length());
+    }
+
+    using iterator = CharType*;
+    using const_iterator = const CharType*;
+    using reverse_iterator = std::reverse_iterator<iterator>;
+    using const_reverse_iterator = std::reverse_iterator<const_iterator>;
+
+    [[gnu::always_inline]]
+    iterator begin() { return type().data(); }
+
+    [[gnu::always_inline]]
+    const_iterator begin() const { return type().data(); }
+
+    [[gnu::always_inline]]
+    iterator end() { return type().data() + (int)type().length(); }
+
+    [[gnu::always_inline]]
+    const_iterator end() const { return type().data() + (int)type().length(); }
+
+    reverse_iterator rbegin() { return reverse_iterator{end()}; }
+    const_reverse_iterator rbegin() const { return const_reverse_iterator{end()}; }
+
+    reverse_iterator rend() { return reverse_iterator{begin()}; }
+    const_reverse_iterator rend() const { return const_reverse_iterator{begin()}; }
+
+    CharType& front() { return *type().data(); }
+    const CharType& front() const { return *type().data(); }
+    CharType& back() { return type().data()[(int)type().length() - 1]; }
+    const CharType& back() const { return type().data()[(int)type().length() - 1]; }
+
+    [[gnu::always_inline]]
+    CharType& operator[](ByteCount pos) { return type().data()[(int)pos]; }
+
+    [[gnu::always_inline]]
+    const CharType& operator[](ByteCount pos) const
+    { return type().data()[(int)pos]; }
 
-class String : public  StringBase
+    Codepoint operator[](CharCount pos) const
+    { return utf8::codepoint(utf8::advance(begin(), end(), pos), end()); }
+
+    CharCount char_length() const { return utf8::distance(begin(), end()); }
+
+    [[gnu::always_inline]]
+    bool empty() const { return type().length() == 0_byte; }
+
+    ByteCount byte_count_to(CharCount count) const
+    { return utf8::advance(begin(), end(), (int)count) - begin(); }
+
+    CharCount char_count_to(ByteCount count) const
+    { return utf8::distance(begin(), begin() + (int)count); }
+
+    StringView substr(ByteCount from, ByteCount length = INT_MAX) const;
+    StringView substr(CharCount from, CharCount length = INT_MAX) const;
+
+private:
+    Type& type() { return *static_cast<Type*>(this); }
+    const Type& type() const { return *static_cast<const Type*>(this); }
+};
+
+class String : public StringOps<String, char>
 {
 public:
+    using Content = std::basic_string<char, std::char_traits<char>,
+                                      Allocator<char, MemoryDomain::String>>;
+
     String() {}
-    String(const char* content) : StringBase(content) {}
-    String(StringBase content) : StringBase(std::move(content)) {}
-    template<typename Char, typename Traits, typename Alloc>
-    String(const std::basic_string<Char, Traits, Alloc>& content) : StringBase(content.begin(), content.end()) {}
-    explicit String(char content, CharCount count = 1) : StringBase((size_t)(int)count, content) {}
+    String(const char* content) : m_data(content) {}
+    String(Content content) : m_data(std::move(content)) {}
+    explicit String(char content, CharCount count = 1) : m_data((size_t)(int)count, content) {}
     explicit String(Codepoint cp, CharCount count = 1)
     {
         while (count-- > 0)
-            utf8::dump(back_inserter(*this), cp);
+            utf8::dump(std::back_inserter(*this), cp);
     }
     template<typename Iterator>
-    String(Iterator begin, Iterator end) : StringBase(begin, end) {}
+    String(Iterator begin, Iterator end) : m_data(begin, end) {}
 
-    StringBase& stdstr() { return *this; }
-    const StringBase& stdstr() const { return *this; }
+    [[gnu::always_inline]]
+    char* data() { return &m_data[0]; }
 
     [[gnu::always_inline]]
-    char      operator[](ByteCount pos) const { return StringBase::operator[]((int)pos); }
+    const char* data() const { return m_data.data(); }
+
     [[gnu::always_inline]]
-    char&     operator[](ByteCount pos) { return StringBase::operator[]((int)pos); }
-    Codepoint operator[](CharCount pos) { return utf8::codepoint(utf8::advance(begin(), end(), pos), end()); }
+    ByteCount length() const { return ByteCount{(int)m_data.length()}; }
 
     [[gnu::always_inline]]
-    ByteCount length() const { return ByteCount{(int)StringBase::length()}; }
-    CharCount char_length() const { return utf8::distance(begin(), end()); }
-    ByteCount byte_count_to(CharCount count) const { return utf8::advance(begin(), end(), (int)count) - begin(); }
-    CharCount char_count_to(ByteCount count) const { return utf8::distance(begin(), begin() + (int)count); }
+    const char* c_str() const { return m_data.c_str(); }
+
+    void append(const char* data, ByteCount count) { m_data.append(data, (size_t)(int)count); }
 
-    String& operator+=(const String& other) { StringBase::operator+=(other); return *this; }
-    String& operator+=(const char* other) { StringBase::operator+=(other); return *this; }
-    String& operator+=(char other) { StringBase::operator+=(other); return *this; }
-    String& operator+=(Codepoint cp) { utf8::dump(back_inserter(*this), cp); return *this; }
+    void push_back(char c) { m_data.push_back(c); }
+    void resize(ByteCount size) { m_data.resize((size_t)(int)size); }
+    void reserve(ByteCount size) { m_data.reserve((size_t)(int)size); }
 
-    StringView substr(ByteCount pos, ByteCount length = INT_MAX) const;
-    StringView substr(CharCount pos, CharCount length = INT_MAX) const;
+private:
+    Content m_data;
 };
 
-class StringView
+class StringView : public StringOps<StringView, const char>
 {
 public:
     constexpr StringView() : m_data{nullptr}, m_length{0} {}
@@ -71,50 +148,17 @@ public:
         : m_data{data}, m_length{length} {}
     constexpr StringView(const char* data) : m_data{data}, m_length{strlen(data)} {}
     constexpr StringView(const char* begin, const char* end) : m_data{begin}, m_length{(int)(end - begin)} {}
-    template<typename Char, typename Traits, typename Alloc>
-    StringView(const std::basic_string<Char, Traits, Alloc>& str) : m_data{str.data()}, m_length{(int)str.length()} {}
+    StringView(const String& str) : m_data{str.data()}, m_length{(int)str.length()} {}
     StringView(const char& c) : m_data(&c), m_length(1) {}
 
-    friend bool operator==(StringView lhs, StringView rhs);
-
     [[gnu::always_inline]]
     const char* data() const { return m_data; }
 
-    using iterator = const char*;
-    using reverse_iterator = std::reverse_iterator<const char*>;
-
-    [[gnu::always_inline]]
-    iterator begin() const { return m_data; }
-    [[gnu::always_inline]]
-    iterator end() const { return m_data + (int)m_length; }
-
-    reverse_iterator rbegin() const { return reverse_iterator{m_data + (int)m_length}; }
-    reverse_iterator rend() const { return reverse_iterator{m_data}; }
-
-    char front() const { return *m_data; }
-    char back() const { return m_data[(int)m_length - 1]; }
-
-    [[gnu::always_inline]]
-    char operator[](ByteCount pos) const { return m_data[(int)pos]; }
-    Codepoint operator[](CharCount pos) { return utf8::codepoint(utf8::advance(begin(), end(), pos), end()); }
-
     [[gnu::always_inline]]
     ByteCount length() const { return m_length; }
-    CharCount char_length() const { return utf8::distance(begin(), end()); }
-
-    [[gnu::always_inline]]
-    bool empty() { return m_length == 0_byte; }
-
-    ByteCount byte_count_to(CharCount count) const;
-    CharCount char_count_to(ByteCount count) const;
-
-    StringView substr(ByteCount from, ByteCount length = INT_MAX) const;
-    StringView substr(CharCount from, CharCount length = INT_MAX) const;
 
     String str() const { return String{begin(), end()}; }
 
-    operator String() const { return str(); } // to remove
-
     struct ZeroTerminatedString
     {
         ZeroTerminatedString(const char* begin, const char* end)
@@ -122,53 +166,37 @@ public:
             if (*end == '\0')
                 unowned = begin;
             else
-                owned = StringBase(begin, end);
+                owned = String::Content(begin, end);
         }
         operator const char*() const { return unowned ? unowned : owned.c_str(); }
 
     private:
-        StringBase owned;
+        String::Content owned;
         const char* unowned = nullptr;
 
     };
     ZeroTerminatedString zstr() const { return ZeroTerminatedString{begin(), end()}; }
 
 private:
+    static constexpr ByteCount strlen(const char* s)
+    {
+        return *s == 0 ? 0 : strlen(s+1) + 1;
+    }
+
     const char* m_data;
     ByteCount m_length;
 };
 
-inline bool operator==(StringView lhs, StringView rhs)
-{
-    return lhs.m_length == rhs.m_length and
-           std::equal(lhs.begin(), lhs.end(), rhs.begin());
-}
-
-inline bool operator!=(StringView lhs, StringView rhs)
-{
-    return not (lhs == rhs);
-}
-
-bool operator<(StringView lhs, StringView rhs);
-
-inline ByteCount StringView::byte_count_to(CharCount count) const
-{
-    return utf8::advance(begin(), end(), (int)count) - begin();
-}
-
-inline CharCount StringView::char_count_to(ByteCount count) const
-{
-    return utf8::distance(begin(), begin() + (int)count);
-}
-
-inline StringView StringView::substr(ByteCount from, ByteCount length) const
+template<typename Type, typename CharType>
+inline StringView StringOps<Type, CharType>::substr(ByteCount from, ByteCount length) const
 {
     if (length < 0)
         length = INT_MAX;
-    return StringView{ m_data + (int)from, std::min(m_length - from, length) };
+    return StringView{ type().data() + (int)from, std::min(type().length() - from, length) };
 }
 
-inline StringView StringView::substr(CharCount from, CharCount length) const
+template<typename Type, typename CharType>
+inline StringView StringOps<Type, CharType>::substr(CharCount from, CharCount length) const
 {
     if (length < 0)
         length = INT_MAX;
@@ -176,70 +204,21 @@ inline StringView StringView::substr(CharCount from, CharCount length) const
     return StringView{ beg, utf8::advance(beg, end(), length) };
 }
 
-inline StringView String::substr(ByteCount pos, ByteCount length) const
-{
-    return StringView{*this}.substr(pos, length);
-}
-
-inline StringView String::substr(CharCount pos, CharCount length) const
-{
-    return StringView{*this}.substr(pos, length);
-}
-
 inline String& operator+=(String& lhs, StringView rhs)
 {
-    lhs.append(rhs.data(), (size_t)(int)rhs.length());
+    lhs.append(rhs.data(), rhs.length());
     return lhs;
 }
 
-inline String operator+(const String& lhs, const String& rhs)
-{
-    String res = lhs;
-    res += rhs;
-    return res;
-}
-
 inline String operator+(StringView lhs, StringView rhs)
 {
-    String res{lhs.begin(), lhs.end()};
-    res += rhs;
-    return res;
-}
-
-inline String operator+(const String& lhs, StringView rhs)
-{
-    String res = lhs;
+    String res;
+    res.reserve((int)(lhs.length() + rhs.length()));
+    res += lhs;
     res += rhs;
     return res;
 }
 
-inline String operator+(StringView lhs, const String& rhs)
-{
-    String res{lhs.begin(), lhs.end()};
-    res.append(rhs);
-    return res;
-}
-
-inline String operator+(const char* lhs, StringView rhs)
-{
-    return StringView{lhs} + rhs;
-}
-
-inline String operator+(StringView lhs, const char* rhs)
-{
-    return lhs + StringView{rhs};
-}
-
-inline String operator+(const char* lhs, const String& rhs)
-{
-    return StringView{lhs} + rhs;
-}
-
-inline String operator+(const String& lhs, const char* rhs)
-{
-    return lhs + StringView{rhs};
-}
-
 Vector<String> split(StringView str, char separator, char escape);
 Vector<StringView> split(StringView str, char separator);
 
@@ -266,16 +245,11 @@ inline String operator"" _str(const char* str, size_t)
     return String(str);
 }
 
-inline StringView operator"" _sv(const char* str, size_t len)
-{
-    return StringView(str, (int)len);
-}
-
 inline String codepoint_to_str(Codepoint cp)
 {
-    StringBase str;
-    utf8::dump(back_inserter(str), cp);
-    return String(str);
+    String str;
+    utf8::dump(std::back_inserter(str), cp);
+    return str;
 }
 
 int str_to_int(StringView str);
@@ -301,16 +275,6 @@ String expand_tabs(StringView line, CharCount tabstop, CharCount col = 0);
 
 Vector<StringView> wrap_lines(StringView text, CharCount max_width);
 
-inline size_t hash_value(const Kakoune::String& str)
-{
-    return hash_data(str.data(), (int)str.length());
-}
-
-inline size_t hash_value(const Kakoune::StringView& str)
-{
-    return hash_data(str.data(), (int)str.length());
-}
-
 }
 
 #endif // string_hh_INCLUDED