From 6172fb983cf8c722499c3be91804ca0ea9d5913c Mon Sep 17 00:00:00 2001
From: Josh Yelon <jyelon@gmail.com>
Date: Tue, 9 Nov 2021 12:46:24 -0500
Subject: [PATCH] Minor bugfix to drivenengine readline mode

---
 luprex/core/cpp/drivenengine.cpp | 14 +++++++-------
 luprex/core/cpp/drivenengine.hpp |  2 +-
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/luprex/core/cpp/drivenengine.cpp b/luprex/core/cpp/drivenengine.cpp
index 712caaa2..9ebb0e7a 100644
--- a/luprex/core/cpp/drivenengine.cpp
+++ b/luprex/core/cpp/drivenengine.cpp
@@ -23,9 +23,9 @@ Channel::~Channel() {
     driven_->channels_[chid_] = nullptr;
 }
 
-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)) {
+void Channel::show_or_hide_command(bool ignore_sb_out) {
+    bool sb_out_empty = (sb_out_->fill() == 0) || ignore_sb_out;
+    if (!sb_out_empty || (!readline_enabled_) || (driven_->stop_driver_)) {
         int ccsize = current_prompt_.size() + current_command_.size();
         readline_echo_ += util::repeat_string("\b \b", ccsize);
         current_prompt_ = "";
@@ -62,7 +62,7 @@ void Channel::show_or_hide_command() {
 
 void Channel::set_prompt(const std::string &p) {
     desired_prompt_ = p;
-    show_or_hide_command();
+    show_or_hide_command(false);
 }
 
 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_or_hide_command();
+            show_or_hide_command(true);
             readline_echo_ = readline_echo_ + " \n";
             sb_in_->write_bytes(desired_command_);
             sb_in_->write_uint8('\n');
@@ -95,7 +95,7 @@ void Channel::feed_readline(int nbytes, const char *bytes) {
 }
 
 void Channel::peek_outgoing(int *nbytes, const char **bytes) {
-    show_or_hide_command();
+    show_or_hide_command(false);
     if (readline_echo_.size() > 0) {
         *nbytes = readline_echo_.size();
         *bytes = readline_echo_.c_str();
@@ -123,7 +123,7 @@ void Channel::set_readline(bool e) {
     if (e != readline_enabled_) {
         readline_enabled_ = e;
         desired_command_ = "";
-        show_or_hide_command();
+        show_or_hide_command(false);
     }
 }
 
diff --git a/luprex/core/cpp/drivenengine.hpp b/luprex/core/cpp/drivenengine.hpp
index 5d4d9ff2..c403df68 100644
--- a/luprex/core/cpp/drivenengine.hpp
+++ b/luprex/core/cpp/drivenengine.hpp
@@ -162,7 +162,7 @@ private:
     void feed_readline(int nbytes, const char *bytes);
     void peek_outgoing(int *nbytes, const char **bytes);
     void sent_outgoing(int nbytes);
-    void show_or_hide_command();
+    void show_or_hide_command(bool ignore_sb_out);
 
 private:
     static const int READLINE_MAX=512;