Lots of work on the lua read-eval-print loop

luprex/cpp/core/luastack.cpp

@@ -336,7 +336,7 @@ eng::string LuaCoreStack::load(LuaSlot result, std::string_view code, std::strin
         const char *str = lua_tolstring(L_, -1, &len);
         eng::string message(str, len);
         lua_pop(L_, 1);
-        if (sv::has_suffix(message, "near <eof>"))
+        if (sv::has_suffix(message, "near <eof>") && sv::is_possible_long_lua_expression(code))
         {
             message = "truncated lua";
         }

luprex/cpp/core/printbuffer.cpp

@@ -192,7 +192,6 @@ bool PrintChanneler::channel(const PrintBuffer *printbuffer, StreamBuffer *sb) {
         line_ = printbuffer->first_line();
     }
     while (line_ < printbuffer->first_unchecked()) {
-        sb->write_bytes("|");
         sb->write_bytes(printbuffer->nth(line_));
         sb->write_bytes("\n");
         line_ += 1;

luprex/cpp/core/util.cpp

@@ -200,6 +200,24 @@ bool is_lua_comment(string_view s) {
     return s.substr(start, 2) == "--";
 }
 
+bool is_possible_long_lua_expression(string_view s) {
+    read_space(s);
+    string_view id = read_lua_identifier(s);
+    if (id.empty()) return false;
+    if ((id == "function") || (id == "if") || (id == "while") || (id == "for") || (id == "repeat") || (id == "do")) return true;
+    if (id == "local")
+    {
+        read_space(s);
+        id = read_lua_identifier(s);
+    }
+    read_space(s);
+    read_prefix(s, "="); // If not present, returns false but we continue anyway.
+    read_space(s);
+    if (has_prefix(s, "[")) return true;
+    if (has_prefix(s, "(")) return true;
+    return false;
+}
+
 bool is_whitespace(string_view s) {
     for (int i = 0; i < int(s.size()); i++) {
         if (!ascii_isspace(s[i])) {

luprex/cpp/core/util.hpp

@@ -106,6 +106,14 @@ bool is_lua_classname(string_view s);
 // Return true if the line of code is a lua comment.
 bool is_lua_comment(string_view s);
 
+// Return true if the line of code could be the beginning of a long expression.
+// In a read-eval-print loop, if the user types something like "function foo",
+// that's not a complete lua expression.  But we don't want to just print an error,
+// we want to give the user a chance to continue typing so that he can turn it
+// into a complete lua expression.  This function returns true if the string looks
+// like the beginning of a long lua expression.  This is only a heuristic.
+bool is_possible_long_lua_expression(string_view s);
+
 // Return true if the line is entirely whitespace.
 bool is_whitespace(string_view s);
 

luprex/cpp/core/world-core.cpp

@@ -1071,6 +1071,10 @@ void World::run_scheduled_threads() {
                     PrettyPrint::Indented().print(LSCO, LuaSpecial(i), &lthread_prints_);
                     lthread_prints_ << std::endl;
                 }
+                if (lthread_prints_.view().empty())
+                {
+                    lthread_prints_ << "ok\n";
+                }
             }
         } else if (status == LUA_YIELD) {
             if (is_authoritative()) {

luprex/lua/login.lua

@@ -40,6 +40,7 @@ function cube.lookmenu(add)
     add("Cube Hi", function () dprint("Doing Cube Hi") end)
     add("Cube Bye", function () dprint("Doing Cube Bye") end)
     add("Cube Yo", function () dprint("Doing Cube Yo") end)
+    add("Cube Z", function () dprint("Doing Cube Z") end)
 end
 
 function sphere.lookhotkeys(add)