Option name completion support

src/main.cc

@@ -1004,15 +1004,27 @@ int main(int argc, char* argv[])
 
     command_manager.register_commands({ "setg", "setglobal" },
                                      [&](const CommandParameters& params, const Context&) { set_option(option_manager, params); },
-                                     CommandManager::None);
+                                     CommandManager::None,
+                                     PerArgumentCommandCompleter({
+                                         [&](const std::string& prefix, size_t cursor_pos)
+                                         { return option_manager.complete_option_name(prefix, cursor_pos); }
+                                     }));
     command_manager.register_commands({ "setb", "setbuffer" },
                                      [&](const CommandParameters& params, const Context& context)
                                      { set_option(context.buffer().option_manager(), params); },
-                                     CommandManager::None);
+                                     CommandManager::None,
+                                     PerArgumentCommandCompleter({
+                                         [&](const std::string& prefix, size_t cursor_pos)
+                                         { return main_context.buffer().option_manager().complete_option_name(prefix, cursor_pos); }
+                                     }));
     command_manager.register_commands({ "setw", "setwindow" },
                                      [&](const CommandParameters& params, const Context& context)
                                      { set_option(context.window().option_manager(), params); },
-                                     CommandManager::None);
+                                     CommandManager::None,
+                                     PerArgumentCommandCompleter({
+                                         [&](const std::string& prefix, size_t cursor_pos)
+                                         { return main_context.window().option_manager().complete_option_name(prefix, cursor_pos); }
+                                     }));
 
     register_highlighters();
     register_filters();

src/option_manager.cc

@@ -12,6 +12,44 @@ std::string int_to_str(int value)
     return oss.str();
 }
 
+Option& OptionManager::operator[] (const std::string& name)
+{
+    auto it = m_options.find(name);
+    if (it != m_options.end())
+        return it->second;
+    else if (m_parent)
+        return (*m_parent)[name];
+    else
+        return m_options[name];
+}
+
+const Option& OptionManager::operator[] (const std::string& name) const
+{
+    auto it = m_options.find(name);
+    if (it != m_options.end())
+        return it->second;
+    else if (m_parent)
+        return (*m_parent)[name];
+    else
+        throw option_not_found(name);
+}
+
+CandidateList OptionManager::complete_option_name(const std::string& prefix,
+                                                  size_t cursor_pos)
+{
+    std::string real_prefix = prefix.substr(0, cursor_pos);
+    CandidateList result;
+    if (m_parent)
+        result = m_parent->complete_option_name(prefix, cursor_pos);
+    for (auto& option : m_options)
+    {
+        if (option.first.substr(0, real_prefix.length()) == real_prefix and
+            not contains(result, option.first))
+            result.push_back(option.first);
+    }
+    return result;
+}
+
 GlobalOptionManager::GlobalOptionManager()
     : OptionManager()
 {

src/option_manager.hh

@@ -3,6 +3,7 @@
 
 #include "utils.hh"
 #include "exception.hh"
+#include "completion.hh"
 
 #include <unordered_map>
 
@@ -39,27 +40,11 @@ public:
     OptionManager(OptionManager& parent)
         : m_parent(&parent) {}
 
-    Option& operator[] (const std::string& name)
+    Option& operator[] (const std::string& name);
-    {
+    const Option& operator[] (const std::string& name) const;
-        auto it = m_options.find(name);
-        if (it != m_options.end())
-            return it->second;
-        else if (m_parent)
-            return (*m_parent)[name];
-        else
-            return m_options[name];
-    }
 
-    const Option& operator[] (const std::string& name) const
+    CandidateList complete_option_name(const std::string& prefix,
-    {
+                                       size_t cursor_pos);
-        auto it = m_options.find(name);
-        if (it != m_options.end())
-            return it->second;
-        else if (m_parent)
-            return (*m_parent)[name];
-        else
-            throw option_not_found(name);
-    }
 
 private:
     OptionManager()