Add machinery to capture result of running a Lua script or snippet.

Add LuaState::expr() that evaluates a Lua snippet and reports back any result
(or error) left on the stack.

Add LLLUAmanager::runScriptFile() and runScriptLine() overloads that accept a
callback with an (int count, LLSD result) signature. The count disambiguates
(error, no result, one result, array of results). Also add overloads that accept
an existing LuaState instance. Also add waitScriptFile() and waitScriptLine()
methods that pause the calling coroutine until the Lua script completes, and
return its results.

Instead of giving LuaState a description to use for all subsequent checkLua()
calls, remove description from its constructor and data members. Move to
expr() and checkLua() parameters: we want a description specific to each
operation, rather than for the LuaState as a whole. This prepares for
persistent LuaState instances.

For now, the existing script_finished_fn semantics remain: the callback will
be called only when the LuaState is destroyed. This may need to change as we
migrate towards longer-lasting LuaState instances.

Make lua_function(name) macro append suffixes to the name for both the
LuaFunction subclass declaration and the instance declaration. This allows
publishing a lua_function() name such as sleep(), which already has a
different C++ declaration.

Move the Lua sleep() entry point to a standalone lua_function(sleep), instead
of a lambda in the body of runScriptFile().

1 files changed, 27 insertions, 3 deletions

diff --git a/indra/newview/llluamanager.h b/indra/newview/llluamanager.h
index 08d9876ce2..bed12e358a 100644
--- a/indra/newview/llluamanager.h
+++ b/indra/newview/llluamanager.h
@@ -27,19 +27,43 @@
 #ifndef LL_LLLUAMANAGER_H
 #define LL_LLLUAMANAGER_H
 
+#include "llsd.h"
 #include <functional>
 #include <string>
+#include <utility>                  // std::pair
+
+class LuaState;
 
 class LLLUAmanager
 {
 public:
+    // Pass a callback with this signature to obtain the error message, if
+    // any, from running a script or source string. Empty msg means success.
     typedef std::function<void(std::string msg)> script_finished_fn;
+    // Pass a callback with this signature to obtain the result, if any, of
+    // running a script or source string.
+    // count <  0 means error, and result.asString() is the error message.
+    // count == 0 with result.isUndefined() means the script returned no results.
+    // count == 1 means the script returned one result.
+    // count >  1 with result.isArray() means the script returned multiple
+    //            results, represented as the entries of the result array.
+    typedef std::function<void(int count, const LLSD& result)> script_result_fn;
+
+    static void runScriptFile(const std::string &filename, script_finished_fn cb = {});
+    static void runScriptFile(const std::string &filename, script_result_fn cb);
+    static void runScriptFile(LuaState& L, const std::string &filename, script_result_fn cb = {});
+    // Run a Lua script file, and pause the calling coroutine until it completes.
+    // The return value is the (count, result) pair described above.
+    static std::pair<int, LLSD> waitScriptFile(LuaState& L, const std::string& filename);
 
-    static void runScriptFile(const std::string &filename, script_finished_fn cb = script_finished_fn());
-    static void runScriptLine(const std::string &cmd, script_finished_fn cb = script_finished_fn());
+    static void runScriptLine(const std::string &cmd, script_finished_fn cb = {});
+    static void runScriptLine(const std::string &cmd, script_result_fn cb);
+    static void runScriptLine(LuaState& L, const std::string &cmd, script_result_fn cb = {});
+    // Run a Lua expression string, and pause the calling coroutine until it completes.
+    // The return value is the (count, result) pair described above.
+    static std::pair<int, LLSD> waitScriptLine(LuaState& L, const std::string& cmd);
 
     static void runScriptOnLogin();
 };
 
-
 #endif