add a Register class, registers can now contain a list of string

That way, registers can be used to store per selection data

src/main.cc

@@ -413,7 +413,7 @@ bool insert_char(IncrementalInserter& inserter, const Key& key)
                     inserter.insert(inserter.buffer().name());
                     break;
                 default:
-                    inserter.insert(RegisterManager::instance()[next_key.key]);
+                    inserter.insert(RegisterManager::instance()[next_key.key].get());
                 }
             }
             break;
@@ -834,9 +834,9 @@ void do_search(Editor& editor)
     {
         std::string ex = prompt("/");
         if (ex.empty())
-            ex = RegisterManager::instance()['/'];
+            ex = RegisterManager::instance()['/'].get();
         else
-            RegisterManager::instance()['/'] = ex;
+            RegisterManager::instance()['/'].set(ex);
 
         editor.select(std::bind(select_next_match, _1, ex));
     }
@@ -845,7 +845,7 @@ void do_search(Editor& editor)
 
 void do_search_next(Editor& editor)
 {
-    std::string& ex = RegisterManager::instance()['/'];
+    const std::string& ex = RegisterManager::instance()['/'].get();
     if (not ex.empty())
         editor.select(std::bind(select_next_match, _1, ex));
     else
@@ -854,18 +854,18 @@ void do_search_next(Editor& editor)
 
 void do_yank(Editor& editor, int count)
 {
-    RegisterManager::instance()['"'] = editor.selection_content();
+    RegisterManager::instance()['"'].set(editor.selection_content());
 }
 
 void do_erase(Editor& editor, int count)
 {
-    RegisterManager::instance()['"'] = editor.selection_content();
+    RegisterManager::instance()['"'].set(editor.selection_content());
     editor.erase();
 }
 
 void do_change(Editor& editor, int count)
 {
-    RegisterManager::instance()['"'] = editor.selection_content();
+    RegisterManager::instance()['"'].set(editor.selection_content());
     do_insert(editor, IncrementalInserter::Mode::Change);
 }
 
@@ -873,9 +873,9 @@ template<bool append>
 void do_paste(Editor& editor, int count)
 {
     if (append)
-        editor.append(RegisterManager::instance()['"']);
+        editor.append(RegisterManager::instance()['"'].get());
     else
-        editor.insert(RegisterManager::instance()['"']);
+        editor.insert(RegisterManager::instance()['"'].get());
 }
 
 void do_select_regex(Editor& editor, int count)

src/register.cc

@@ -0,0 +1,35 @@
+#include "register.hh"
+
+namespace Kakoune
+{
+
+const std::string Register::ms_empty;
+
+void Register::set(const std::string& value)
+{
+    m_content.clear();
+    m_content.push_back(value);
+}
+
+void Register::set(const memoryview<std::string>& values)
+{
+    m_content = std::vector<std::string>(values.begin(), values.end());
+}
+
+const std::string& Register::get() const
+{
+    if (m_content.size() != 0)
+        return m_content.front();
+    else
+        return ms_empty;
+}
+
+const std::string& Register::get(size_t index) const
+{
+    if (m_content.size() > index)
+        return m_content[index];
+    else
+        return ms_empty;
+}
+
+}

src/register.hh

@@ -0,0 +1,29 @@
+#ifndef register_hh_INCLUDED
+#define register_hh_INCLUDED
+
+#include <string>
+#include <vector>
+
+#include "memoryview.hh"
+
+namespace Kakoune
+{
+
+class Register
+{
+public:
+    void set(const std::string& value);
+    void set(const memoryview<std::string>& values);
+    const std::string& get() const;
+    const std::string& get(size_t index) const;
+
+private:
+    std::vector<std::string> m_content;
+
+    static const std::string ms_empty;
+};
+
+}
+
+#endif // register_hh_INCLUDED
+

src/register_manager.hh

@@ -1,6 +1,7 @@
 #ifndef register_manager_hh_INCLUDED
 #define register_manager_hh_INCLUDED
 
+#include "register.hh"
 #include "utils.hh"
 
 namespace Kakoune
@@ -9,10 +10,10 @@ namespace Kakoune
 class RegisterManager : public Singleton<RegisterManager>
 {
 public:
-    std::string& operator[](char reg) { return m_registers[reg]; }
+    Register& operator[](char reg) { return m_registers[reg]; }
 
 protected:
-    std::unordered_map<char, std::string> m_registers;
+    std::unordered_map<char, Register> m_registers;
 };
 
 }