napi: implement exception handling

Re gh-27
Re gh-49

src/node_jsrtapi.cc

@@ -918,49 +918,6 @@ napi_value napi_make_callback(napi_env e, napi_value recv,
 	return reinterpret_cast<napi_value>(result);
 }
 
-bool napi_try_catch(napi_env e, napi_try_callback cbtry,
-  napi_catch_callback cbcatch, void* data) {
-  JsValueRef error = JS_INVALID_REFERENCE;
-  bool hasException;
-  cbtry(e, data);
-  if (error = JS_INVALID_REFERENCE) {
-    JsErrorCode errorCode = JsHasException(&hasException);
-    if (errorCode != JsNoError) {
-      // If script is in disabled state, no need to fail here.
-      // We will fail subsequent calls to Jsrt anyway.
-      assert(errorCode == JsErrorInDisabledState);
-    } else if (hasException) {
-      JsValueRef exceptionRef;
-      errorCode = JsGetAndClearException(&exceptionRef);
-      // We came here through JsHasException, so script shouldn't be in disabled
-      // state.
-      assert(errorCode != JsErrorInDisabledState);
-      if (errorCode == JsNoError) {
-        error = exceptionRef;
-      }
-    }
-  }
-  if(error != JS_INVALID_REFERENCE) {
-    cbcatch(e, data);
-    return true;
-  }
-  JsErrorCode errorCode = JsHasException(&hasException);
-  if (errorCode != JsNoError) {
-    if (errorCode == JsErrorInDisabledState) {
-      cbcatch(e, data);
-      return true;
-    }
-    // Should never get errorCode other than JsNoError/JsErrorInDisabledState
-    assert(false);
-    return false;
-  }
-  if (hasException) {
-    cbcatch(e, data);
-    return true;
-  }
-  return false;
-}
-
 struct ArrayBufferFinalizeInfo {
   void *data;
 
@@ -1020,3 +977,15 @@ size_t napi_buffer_length(napi_env e, napi_value v) {
     return 0;
   return len;
 }
+
+bool napi_is_exception_pending(napi_env) {
+  bool returnValue = false;
+  JsErrorCode error = JsHasException(&returnValue);
+  return returnValue;
+}
+
+napi_value napi_get_and_clear_last_exception(napi_env e) {
+  JsValueRef lastException = napi_get_undefined_(e);
+  JsErrorCode error = JsGetAndClearException(&lastException);
+  return reinterpret_cast<napi_value>(lastException);
+}

src/node_jsvmapi.h

@@ -242,16 +242,9 @@ NODE_EXTERN void napi_throw(napi_env e, napi_value error);
 NODE_EXTERN void napi_throw_error(napi_env e, char* msg);
 NODE_EXTERN void napi_throw_type_error(napi_env e, char* msg);
 
-// TODO(ianhall): APIs for handling try catch semantics need serious
-// design analysis, this is just a quick hack
-// One thing to note is that v8::TryCatch relies on the current
-// stack pointer position, so it cannot be used
-// with a wrapper class hack like we're doing for handle scopes.
-typedef void (*napi_try_callback)(napi_env e, void* data);
-typedef void (*napi_catch_callback)(napi_env e, void* data);
-NODE_EXTERN bool napi_try_catch(napi_env e, napi_try_callback t,
-                                napi_catch_callback c, void* data);
-
+// Methods to support catching exceptions
+NODE_EXTERN bool napi_is_exception_pending(napi_env e);
+NODE_EXTERN napi_value napi_get_and_clear_last_exception(napi_env e);
 
 // Methods to provide node::Buffer functionality with napi types
 NODE_EXTERN napi_value napi_buffer_new(napi_env e, char* data, uint32_t size);