Refactor luaconsole to make it easier to use

luprex/core/cpp/luaconsole.hpp

@@ -3,22 +3,26 @@
 // LuaConsole:
 //
 // Used to parse commands that are being interactively typed
-// in by a user.
+// in by a user.  The common usage pattern is:
 //
-// The command syntax is always a single character command,
-// followed by arguments.  Only two commands are hardwired:
+//    1. Print the prompt suggested by 'get_prompt'.
+//    2. Read a line of text from stdin.
+//    3. Add the line to the LuaConsole using 'add'.
+//    4. Get the command words using 'words'.
+//    5. If the words are empty, do nothing.
+//    6. If the words contain something, execute and call 'clear'.
 //
-//    l - evaluate lua expression
-//    r - evaluate lua expression with 'return' prepended
+// The 'words' returned by the luaconsole can be empty, meaning
+// that there's no command to execute.  If the words are nonempty,
+// then the first word is the command.  There are two hardwired
+// commands:
 //
-// The console expects you to add lines of text one at a time.
-// After adding a line, the console will recommend one of these
-// actions:
+//    lua <expr> - execute a lua expression
+//    syntax <message> - print a syntax error message
 //
-// 1. DO_NOTHING: Add more lines of text.
-// 2. DO_LUA: Evaluate a lua expression.
-// 3. DO_OTHER: Execute a non-lua command.
-// 4. DO_SYNTAX: Print a lua syntax error.
+// If the first word is anything else, it means the user typed
+// that word on the command line.   It is up to you to interpret
+// such commands.
 //
 //////////////////////////////////////////////////////
 
@@ -30,46 +34,34 @@
 
 class LuaConsole {
 public:
-    enum {
-        DO_NOTHING,  // We need more input text.
-        DO_COMMAND,  // We have a valid slash command.
-        DO_LUA,      // We have a valid lua expression.
-        DO_SYNTAX,   // We have a syntax error.
-    };
     using StringVec = std::vector<std::string>;
 
 private:
     lua_State *lua_state_;
-    int action_;
     std::string raw_input_;
     int lines_;
-    std::string lua_expression_;
     StringVec words_;
-    std::string syntax_;
     std::string prompt_;
 
     void split_words();
+    void clear_command();
 
 public:
     LuaConsole();
     ~LuaConsole();
 
-    // Get the recommended action.
-    int action() const { return action_; }
-
     // Fetch the stored prompt.  Also clears the stored prompt. You should fetch
     // and print the prompt after 'add' or 'clear'.
     std::string get_prompt();
     
-    // When action is DO_COMMAND, get the command words.
+    // Get the command words.
+    //
+    // Returns the empty vector if there is no command.
+    // If there is a command, the first word is the command word.
+    // See the file comment for certain built-in command words.
+    // 
     const StringVec &words() const { return words_; }
 
-    // When action is DO_LUA, get the valid lua expression.
-    std::string lua_expression() const { return lua_expression_; }
-
-    // When action is DO_SYNTAX, get the syntax error.
-    const std::string &syntax() const { return syntax_; }
-
     // Add a line of text that was just read from the console.
     // If more input is needed, stores the ">> " prompt.
     void add(std::string line);