Refactor OptionManager, add OptionManagerWatcher

- use set_option to set an option, instead of operator[] (no-const)
- keeps a list of OptionManagerWatcher to notify when an option change
  it also notifies when an option changes in his parent and the option
  is not overridden.

src/commands.cc

@@ -640,13 +640,12 @@ void exec_commands_in_runtime_file(const CommandParameters& params,
 }
 
 void set_option(OptionManager& option_manager, const CommandParameters& params,
-                HookManager& hook_manager, const Context& context)
+                const Context& context)
 {
     if (params.size() != 2)
         throw wrong_argument_count();
 
-    option_manager[params[0]] = params[1];
-    hook_manager.run_hook("SetOption", params[0] + "=" + params[1], context);
+    option_manager.set_option(params[0], Option(params[1]));
 }
 
 class RegisterRestorer
@@ -920,7 +919,7 @@ void register_commands()
 
     cm.register_commands({ "setg", "setglobal" },
                          [](const CommandParameters& params, const Context& context)
-                         { set_option(GlobalOptionManager::instance(), params, GlobalHookManager::instance(), context); },
+                         { set_option(GlobalOptionManager::instance(), params, context); },
                          CommandManager::None,
                          PerArgumentCommandCompleter({
                              [](const String& prefix, size_t cursor_pos)
@@ -928,7 +927,7 @@ void register_commands()
                          }));
     cm.register_commands({ "setb", "setbuffer" },
                          [](const CommandParameters& params, const Context& context)
-                         { set_option(context.buffer().option_manager(), params, context.buffer().hook_manager(), context); },
+                         { set_option(context.buffer().option_manager(), params, context); },
                          CommandManager::None,
                          PerArgumentCommandCompleter({
                              [](const String& prefix, size_t cursor_pos)
@@ -936,7 +935,7 @@ void register_commands()
                          }));
     cm.register_commands({ "setw", "setwindow" },
                          [](const CommandParameters& params, const Context& context)
-                         { set_option(context.window().option_manager(), params, context.window().hook_manager(), context); },
+                         { set_option(context.window().option_manager(), params, context); },
                          CommandManager::None,
                          PerArgumentCommandCompleter({
                              [](const String& prefix, size_t cursor_pos)

src/option_manager.cc

@@ -1,35 +1,51 @@
 #include "option_manager.hh"
+#include "assert.hh"
 
 #include <sstream>
 
 namespace Kakoune
 {
 
-Option& OptionManager::operator[] (const String& name)
+OptionManager::OptionManager(OptionManager& parent)
+    : m_parent(&parent)
 {
-    auto it = m_options.find(name);
-    if (it != m_options.end())
-        return it->second;
-    else
+    parent.register_watcher(*this);
+}
+
+OptionManager::~OptionManager()
+{
+    if (m_parent)
+        m_parent->unregister_watcher(*this);
+
+    assert(m_watchers.empty());
+}
+
+void OptionManager::register_watcher(OptionManagerWatcher& watcher)
+{
+    assert(not contains(m_watchers, &watcher));
+    m_watchers.push_back(&watcher);
+}
+
+void OptionManager::unregister_watcher(OptionManagerWatcher& watcher)
+{
+    auto it = find(m_watchers.begin(), m_watchers.end(), &watcher);
+    assert(it != m_watchers.end());
+    m_watchers.erase(it);
+}
+
+void OptionManager::set_option(const String& name, const Option& value)
+{
+    Option old_value = m_options[name];
+    m_options[name] = value;
+
+    if (old_value != value)
     {
-        Option& res = m_options[name];
-        OptionManager* parent = m_parent;
-        while (parent)
-        {
-            auto parent_it = parent->m_options.find(name);
-            if (parent_it != parent->m_options.end())
-            {
-                res = parent_it->second;
-                break;
-            }
-            else
-               parent = parent->m_parent;
-        }
-        return res;
+        for (auto watcher : m_watchers)
+            watcher->on_option_changed(name, value);
     }
 }
 
-const Option& OptionManager::operator[] (const String& name) const
+const Option& OptionManager::operator[](const String& name) const
 {
     auto it = m_options.find(name);
     if (it != m_options.end())
@@ -56,10 +72,28 @@ CandidateList OptionManager::complete_option_name(const String& prefix,
     return result;
 }
 
+OptionManager::OptionMap OptionManager::flatten_options() const
+{
+    OptionMap res = m_parent ? m_parent->flatten_options() : OptionMap();
+    for (auto& option : m_options)
+        res.insert(option);
+    return res;
+}
+
+void OptionManager::on_option_changed(const String& name, const Option& value)
+{
+    // if parent option changed, but we overrided it, it's like nothing happened
+    if (m_options.find(name) != m_options.end())
+        return;
+
+    for (auto watcher : m_watchers)
+        watcher->on_option_changed(name, value);
+}
+
 GlobalOptionManager::GlobalOptionManager()
     : OptionManager()
 {
-    (*this)["tabstop"] = 8;
+    set_option("tabstop", Option(8));
 }
 
 }

src/option_manager.hh

@@ -28,32 +28,56 @@ public:
     Option& operator=(int value) { m_value = int_to_str(value); return *this; }
     Option& operator=(const String& value) { m_value = value; return *this; }
 
+    bool operator==(const Option& other) const { return m_value == other.m_value; }
+    bool operator!=(const Option& other) const { return m_value != other.m_value; }
+
     int    as_int()    const  { return atoi(m_value.c_str()); }
     String as_string() const { return m_value; }
 private:
     String m_value;
 };
 
-class OptionManager
+class OptionManagerWatcher
 {
 public:
-    OptionManager(OptionManager& parent)
-        : m_parent(&parent) {}
+    virtual ~OptionManagerWatcher() {}
+
+    virtual void on_option_changed(const String& name,
+                                   const Option& option) = 0;
+};
+
+class OptionManager : private OptionManagerWatcher
+{
+public:
+    OptionManager(OptionManager& parent);
+    ~OptionManager();
 
-    Option& operator[] (const String& name);
     const Option& operator[] (const String& name) const;
 
+    void set_option(const String& name, const Option& value);
+
     CandidateList complete_option_name(const String& prefix,
                                        size_t cursor_pos);
 
+    typedef std::unordered_map<String, Option> OptionMap;
+    OptionMap flatten_options() const;
+
+    void register_watcher(OptionManagerWatcher& watcher);
+    void unregister_watcher(OptionManagerWatcher& watcher);
+
 private:
     OptionManager()
         : m_parent(nullptr) {}
     // the only one allowed to construct a root option manager
     friend class GlobalOptionManager;
 
-    std::unordered_map<String, Option> m_options;
+    OptionMap m_options;
     OptionManager* m_parent;
+
+    void on_option_changed(const String& name,
+                           const Option& value);
+
+    std::vector<OptionManagerWatcher*> m_watchers;
 };
 
 class GlobalOptionManager : public OptionManager,