Lua: print() can print any type, add tostringx() for print-to-string

include/lua/internal.hpp

@@ -5,6 +5,8 @@
 #include <cstdio>
 #include <cstdlib>
 #include <iostream>
+#include <list>
+#include <functional>
 extern "C"
 {
 #include <lua.h>
@@ -19,6 +21,9 @@ extern bool lua_booted_flag;
 extern uint64_t lua_idle_hook_time;
 extern uint64_t lua_timer_hook_time;
 
+std::list<std::string(*)(lua_State* LS, int index)>& userdata_recogn_fns();
+std::string try_recognize_userdata(lua_State* LS, int index);
+
 template<typename T>
 T get_numeric_argument(lua_State* LS, unsigned argindex, const char* fname)
 {
@@ -90,6 +95,7 @@ public:
 	lua_class(const std::string& _name)
 	{
 		name = _name;
+		userdata_recogn_fns().push_back(lua_class<T>::recognize);
 	}
 
 	template<typename... U> T* _create(lua_State* LS, U... args)
@@ -208,6 +214,16 @@ badtype:
 		return objclass<T>()._is(LS, arg);
 	}
 
+	std::string _recognize(lua_State* LS, int arg)
+	{
+		return _is(LS, arg) ? name : "";
+	}
+
+	static std::string recognize(lua_State* LS, int arg)
+	{
+		return objclass<T>()._recognize(LS, arg);
+	}
+
 	lua_obj_pin<T>* _pin(lua_State* LS, int arg, const char* fname)
 	{
 		T* obj = get(LS, arg, fname);

manual.lyx

@@ -1923,6 +1923,15 @@ print
 Print line to message console.
 \end_layout
 
+\begin_layout Subsubsection
+tostringx
+\end_layout
+
+\begin_layout Standard
+Convert arbitrary lua value into a string (using same conversions as print)
+ and return the result.
+\end_layout
+
 \begin_layout Subsubsection
 exec(string command)
 \end_layout

manual.txt

@@ -940,36 +940,41 @@ Sets the delay for subsequent characters in typematic autorepeat.
 
 Print line to message console.
 
-8.1.2 exec(string command)
+8.1.2 tostringx
+
+Convert arbitrary lua value into a string (using same conversions 
+as print) and return the result.
+
+8.1.3 exec(string command)
 
 Run command as it was entered on the command line
 
-8.1.3 utime()
+8.1.4 utime()
 
 Returns two values. First is time since some epoch in seconds, 
 the second is microseconds mod 10^6 since that epoch.
 
-8.1.4 emulator_ready()
+8.1.5 emulator_ready()
 
 Returns true if emulator has finished booting, false if not 
 (on_startup() will be issued later).
 
-8.1.5 set_idle_timeout(number timeout)
+8.1.6 set_idle_timeout(number timeout)
 
 Set number of microseconds to block idle for. After this timeout 
 has expired, on_idle() will be called once.
 
-8.1.6 set_timer_timeout(number timeout)
+8.1.7 set_timer_timeout(number timeout)
 
 Set number of microseconds to block timer for. After this timeout 
 has expired, on_timer() will be called once.
 
-8.1.7 bus_address(number snesaddr)
+8.1.8 bus_address(number snesaddr)
 
 Returns virtual address corresponding to specified address on 
 SNES bus.
 
-8.1.8 loopwrapper(function fun, ...)
+8.1.9 loopwrapper(function fun, ...)
 
 Calls function fun with function and specified arguments. The 
 function passed suspends execution until the function returned is 
@@ -988,21 +993,21 @@ on_paint = loopwrapper(function(wait)
 
 end);
 
-8.1.9 list_bindings([string cmd])
+8.1.10 list_bindings([string cmd])
 
 Get table of all keybindings, indexed by keyspec 
 (modifiers|mask/key). If command is specified, the table is 
 limited to that command.
 
-8.1.10 get_alias(string aname)
+8.1.11 get_alias(string aname)
 
 Get expansion of given alias.
 
-8.1.11 set_alias(string aname, string value)
+8.1.12 set_alias(string aname, string value)
 
 Set expansion of given alias.
 
-8.1.12 create_ibind(string name, string cmd)
+8.1.13 create_ibind(string name, string cmd)
 
 Return object representing inverse binding with specified name 
 and specified command.

src/lua/core.cpp

@@ -3,9 +3,75 @@
 #include "lua/internal.hpp"
 #include "core/framerate.hpp"
 #include "core/window.hpp"
+#include "library/string.hpp"
+#include <sstream>
 
 namespace
 {
+	std::string luavalue_to_string(lua_State* LS, int index, std::set<const void*>& printed, bool quote)
+	{
+		switch(lua_type(LS, index)) {
+		case LUA_TNONE:
+			return "none";
+		case LUA_TNIL:
+			return "nil";
+		case LUA_TBOOLEAN:
+			return lua_toboolean(LS, index) ? "true" : "false";
+		case LUA_TNUMBER:
+			return (stringfmt() << lua_tonumber(LS, index)).str();
+		case LUA_TSTRING: {
+			const char* tmp2;
+			size_t len;
+			tmp2 = lua_tolstring(LS, index, &len);
+			if(quote)
+				return "\"" + std::string(tmp2, tmp2 + len) + "\"";
+			else
+				return std::string(tmp2, tmp2 + len);
+		}
+		case LUA_TLIGHTUSERDATA:
+			return (stringfmt() << "Lightuserdata:" << lua_touserdata(LS, index)).str();
+		case LUA_TFUNCTION:
+			return (stringfmt() << "Function:" << lua_topointer(LS, index)).str();
+		case LUA_TTHREAD:
+			return (stringfmt() << "Thread:" << lua_topointer(LS, index)).str();
+			break;
+		case LUA_TUSERDATA:
+			return (stringfmt() << "Userdata<" << try_recognize_userdata(LS, index) << ">:"
+				<< lua_touserdata(LS, index)).str();
+		case LUA_TTABLE: {
+			//Fun with recursion.
+			const void* ptr = lua_topointer(LS, index);
+			if(printed.count(ptr))
+				return (stringfmt() << "<table:" << ptr << ">").str();
+			printed.insert(ptr);
+			std::ostringstream s;
+			s << "<" << ptr << ">{";
+			lua_pushnil(LS);
+			bool first = true;
+			while(lua_next(LS, index)) {
+				if(!first)
+					s << ", ";
+				int stacktop = lua_gettop(LS);
+				s << "[" << luavalue_to_string(LS, stacktop - 1, printed, true) << "]="
+					<< luavalue_to_string(LS, stacktop, printed, true);
+				first = false;
+				lua_pop(LS, 1);
+			}
+			s << "}";
+			return s.str();
+		}
+		default:
+			return (stringfmt() << "???:" << lua_topointer(LS, index)).str();
+		}
+	}
+
+	function_ptr_luafun lua_tostringx("tostringx", [](lua_State* LS, const std::string& fname) -> int {
+		std::set<const void*> tmp2;
+		std::string y = luavalue_to_string(LS, 1, tmp2, false);
+		lua_pushlstring(LS, y.c_str(), y.length());
+		return 1;
+	});
+
 	function_ptr_luafun lua_print("print", [](lua_State* LS, const std::string& fname) -> int {
 		int stacksize = 0;
 		while(!lua_isnone(LS, stacksize + 1))
@@ -13,29 +79,12 @@ namespace
 		std::string toprint;
 		bool first = true;
 		for(int i = 0; i < stacksize; i++) {
-			size_t len;
-			const char* tmp = NULL;
-			if(lua_isnil(LS, i + 1)) {
-				tmp = "nil";
-				len = 3;
-			} else if(lua_isboolean(LS, i + 1) && lua_toboolean(LS, i + 1)) {
-				tmp = "true";
-				len = 4;
-			} else if(lua_isboolean(LS, i + 1) && !lua_toboolean(LS, i + 1)) {
-				tmp = "false";
-				len = 5;
-			} else {
-				tmp = lua_tolstring(LS, i + 1, &len);
-				if(!tmp) {
-					tmp = "(unprintable)";
-					len = 13;
-				}
-			}
-			std::string localmsg(tmp, tmp + len);
+			std::set<const void*> tmp2;
+			std::string tmp = luavalue_to_string(LS, i + 1, tmp2, false);
 			if(first)
-				toprint = localmsg;
+				toprint = tmp;
 			else
-				toprint = toprint + "\t" + localmsg;
+				toprint = toprint + "\t" + tmp;
 			first = false;
 		}
 		platform::message(toprint);

src/lua/lua.cpp

@@ -670,6 +670,33 @@ bool lua_do_once(lua_State* LS, void* key)
 	}
 }
 
+std::list<std::string(*)(lua_State* LS, int index)>& userdata_recogn_fns()
+{
+	static std::list<std::string(*)(lua_State* LS, int index)> x;
+	return x;
+}
+
+std::string try_recognize_userdata(lua_State* LS, int index)
+{
+	for(auto i : userdata_recogn_fns()) {
+		std::string x = i(LS, index);
+		if(x != "")
+			return x;
+	}
+	//Hack: Lua builtin file objects.
+	lua_pushstring(LS, "FILE*");
+	lua_rawget(LS, LUA_REGISTRYINDEX);
+	if(lua_getmetatable(LS, index)) {
+		if(lua_rawequal(LS, -1, -2)) {
+			lua_pop(LS, 2);
+			return "FILE*";
+		}
+		lua_pop(LS, 1);
+	}
+	lua_pop(LS, 1);
+	return "unknown";
+}
+
 bool lua_requests_repaint = false;
 bool lua_requests_subframe_paint = false;
 bool lua_supported = true;