Add a %val{...} expand type

%val{name} gives access to values given in shell through $kak_<name>

src/command_manager.cc

@@ -55,6 +55,7 @@ struct Token
         ShellExpand,
         RegisterExpand,
         OptionExpand,
+        ValExpand,
         CommandSeparator
     };
     Token() : m_type(Type::Raw) {}
@@ -150,6 +151,8 @@ Token::Type token_type(StringView type_name)
         return Token::Type::RegisterExpand;
     else if (type_name == "opt")
         return Token::Type::OptionExpand;
+    else if (type_name == "val")
+        return Token::Type::ValExpand;
     else if (type_name == "rec")
         return Token::Type::RawEval;
     else if (throw_on_invalid)
@@ -316,6 +319,8 @@ String eval_token(const Token& token, Context& context,
         return RegisterManager::instance()[content].values(context)[0];
     case Token::Type::OptionExpand:
         return context.options()[content].get_as_string();
+    case Token::Type::ValExpand:
+        return ShellManager::instance().get_val(content, context);
     case Token::Type::RawEval:
         return eval(content, context, shell_params, env_vars);
     case Token::Type::Raw:

src/shell_manager.cc

@@ -107,23 +107,14 @@ String ShellManager::pipe(StringView input,
             if (local_var != env_vars.end())
                 setenv(("kak_" + name).c_str(), local_var->second.c_str(), 1);
             else
-            {
-                auto env_var = std::find_if(
-                    m_env_vars.begin(), m_env_vars.end(),
-                    [&](const std::pair<Regex, EnvVarRetriever>& pair)
-                    { return boost::regex_match(name.begin(), name.end(),
-                                                pair.first); });
-
-                if (env_var != m_env_vars.end())
             {
                 try
                 {
-                        String value = env_var->second(name, context);
+                    String value = get_val(name, context);
                     setenv(("kak_"_str + name).c_str(), value.c_str(), 1);
                 }
                 catch (runtime_error&) {}
             }
-            }
 
             ++it;
         }
@@ -149,4 +140,17 @@ void ShellManager::register_env_var(StringView regex,
     m_env_vars.push_back({ Regex(regex.begin(), regex.end()), std::move(retriever) });
 }
 
+String ShellManager::get_val(StringView name, const Context& context) const
+{
+    auto env_var = std::find_if(
+        m_env_vars.begin(), m_env_vars.end(),
+        [&](const std::pair<Regex, EnvVarRetriever>& pair)
+        { return boost::regex_match(name.begin(), name.end(),
+                                    pair.first); });
+
+    if (env_var == m_env_vars.end())
+        throw runtime_error("no such env var: " + name);
+    return env_var->second(name, context);
+}
+
 }

src/shell_manager.hh

@@ -28,6 +28,7 @@ public:
                 int* exit_status = nullptr);
 
     void register_env_var(StringView regex, EnvVarRetriever retriever);
+    String get_val(StringView name, const Context& context) const;
 
 private:
     std::vector<std::pair<Regex, EnvVarRetriever>> m_env_vars;