From 712b4bed9973c60b5c139f98e51ed804ce8a628d Mon Sep 17 00:00:00 2001
From: Nicolas Noble <nnoble@blizzard.com>
Date: Wed, 24 Jul 2013 14:23:25 -0700
Subject: Better exception handling support for Lua.

---
 includes/LuaTask.h |  6 ++++--
 src/BLua.cc        | 21 +++++++++++++++++----
 src/LuaTask.cc     | 17 +++++++++++++++++
 3 files changed, 38 insertions(+), 6 deletions(-)

diff --git a/includes/LuaTask.h b/includes/LuaTask.h
index 50226cd..1f7a0b5 100644
--- a/includes/LuaTask.h
+++ b/includes/LuaTask.h
@@ -12,10 +12,11 @@ class LuaMainTask;
 class LuaExecCell {
   public:
       LuaExecCell();
-      virtual ~LuaExecCell() { }
+      virtual ~LuaExecCell() { if (m_exception) delete m_exception; }
     void detach() { m_detached = true; }
     void exec(LuaMainTask * mainTask);
-    bool gotError() { return m_gotError; }
+    bool gotError() { return m_gotError || m_exception; }
+    void throwError() throw (GeneralException);
   protected:
     virtual void run(Lua &) = 0;
     void setError() { m_gotError = true; }
@@ -23,6 +24,7 @@ class LuaExecCell {
     Events::Async m_event;
     bool m_detached = false;
     bool m_gotError = false;
+    GeneralException * m_exception = NULL;
     friend class LuaTask;
 
       LuaExecCell(const LuaExecCell &) = delete;
diff --git a/src/BLua.cc b/src/BLua.cc
index 21a7452..29b68c2 100644
--- a/src/BLua.cc
+++ b/src/BLua.cc
@@ -474,12 +474,19 @@ Balau::String Balau::Lua::tostring(int i) {
 struct LoadF {
     Balau::IO<Balau::Handle> f;
     char buff[BUFFERSIZE];
+    Balau::GeneralException * exception = NULL;
 };
 
 const char * Balau::LuaStatics::getF(lua_State * L, void * ud, size_t * size) {
     LoadF * lf = (LoadF *)ud;
 
-    *size = lf->f->read(lf->buff, BUFFERSIZE);
+    try {
+        *size = lf->f->read(lf->buff, BUFFERSIZE);
+    }
+    catch (GeneralException e) {
+        lf->exception = new GeneralException(e);
+        AssertHelper("LuaJIT is lame.");
+    }
     return (*size > 0) ? lf->buff : NULL;
 }
 
@@ -522,9 +529,15 @@ void Balau::Lua::load(IO<Handle> h, bool docall) throw (GeneralException) {
     status = lua_load(L, LuaStatics::getF, &lf, name.to_charp());
 
     if (status) {
-        pushLuaContext();
-        showerror();
-        throw LuaException(String("Error loading lua chunk from Handle `") + h->getName() + "'");
+        if (lf.exception) {
+            GeneralException copy(*lf.exception);
+            delete lf.exception;
+            throw copy;
+        } else {
+            pushLuaContext();
+            showerror();
+            throw LuaException(String("Error loading lua chunk from Handle `") + h->getName() + "'");
+        }
     }
 
     if (docall)
diff --git a/src/LuaTask.cc b/src/LuaTask.cc
index 12d4435..fc92cdf 100644
--- a/src/LuaTask.cc
+++ b/src/LuaTask.cc
@@ -60,6 +60,9 @@ void Balau::LuaTask::Do() {
     try {
         m_cell->run(L);
     }
+    catch (GeneralException e) {
+        m_cell->m_exception = new GeneralException(e);
+    }
     catch (...) {
         m_cell->setError();
     }
@@ -77,6 +80,20 @@ void Balau::LuaExecCell::exec(LuaMainTask * mainTask) {
         Task::operationYield(&m_event);
 }
 
+void Balau::LuaExecCell::throwError() throw (GeneralException) {
+    if (!gotError())
+        return;
+
+    if (m_exception) {
+        GeneralException copy(*m_exception);
+        delete m_exception;
+        m_exception = NULL;
+        throw copy;
+    } else {
+        throw GeneralException("Unknown error");
+    }
+}
+
 void Balau::LuaExecString::run(Lua & L) {
     L.load(m_str);
 }
-- 
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