Even more sophisticated readline functionality

luprex/core/cpp/drivenengine.cpp

@@ -23,7 +23,16 @@ Channel::~Channel() {
     driven_->channels_[chid_] = nullptr;
 }
 
-void Channel::show_command() {
+void Channel::show_or_hide_command() {
+    // Decide if we should hide the command, and if so, do it.
+    if ((!readline_enabled_) || (driven_->stop_driver_) || (sb_out_->fill() > 0)) {
+        int ccsize = current_prompt_.size() + current_command_.size();
+        readline_echo_ += util::repeat_string("\b \b", ccsize);
+        current_prompt_ = "";
+        current_command_ = "";
+        return;
+    }
+
     // If the prompt has changed, erase everything and start over.
     if (desired_prompt_ != current_prompt_) {
         int ccsize = current_prompt_.size() + current_command_.size();
@@ -51,18 +60,9 @@ void Channel::show_command() {
     }
 }
 
-void Channel::hide_command() {
-    int ccsize = current_command_.size() + current_prompt_.size();
-    if (ccsize > 0) {
-        readline_echo_ += util::repeat_string("\b \b", ccsize);
-        current_command_ = "";
-        current_prompt_ = "";
-    }
-}
-
 void Channel::set_prompt(const std::string &p) {
     desired_prompt_ = p;
-    if (readline_enabled_) show_command();
+    show_or_hide_command();
 }
 
 void Channel::feed_readline(int nbytes, const char *bytes) {
@@ -72,7 +72,7 @@ void Channel::feed_readline(int nbytes, const char *bytes) {
             // Ignore newline immediately after carriage return.
             // Otherwise, crlf produces two newlines.
         } else if ((c == '\r') || (c == '\n')) {
-            show_command();
+            show_or_hide_command();
             readline_echo_ = readline_echo_ + " \n";
             sb_in_->write_bytes(desired_command_);
             sb_in_->write_uint8('\n');
@@ -95,11 +95,7 @@ void Channel::feed_readline(int nbytes, const char *bytes) {
 }
 
 void Channel::peek_outgoing(int *nbytes, const char **bytes) {
-    if (sb_out_->fill() > 0) {
-        hide_command();
-    } else if (readline_enabled_) {
-        show_command();
-    }
+    show_or_hide_command();
     if (readline_echo_.size() > 0) {
         *nbytes = readline_echo_.size();
         *bytes = readline_echo_.c_str();
@@ -127,6 +123,7 @@ void Channel::set_readline(bool e) {
     if (e != readline_enabled_) {
         readline_enabled_ = e;
         desired_command_ = "";
+        show_or_hide_command();
     }
 }