issue #262: more verbose error messages when loading broken modules

js/common/bootstrap/modules.js

@@ -87,23 +87,33 @@ Module.prototype.require = function (path) {
   // locate file and read content
   raw = ModuleCache["/internal"].exports.readFile(path);
 
+  // test for parse errors first and fail early if a parse error detected
+  if (! SYS_PARSE(raw.content, path)) {
+    throw "Javascript parse error in file '" + path + "'";
+  }
+
   // create a new sandbox and execute
   module = ModuleCache[path] = new Module(path);
 
   content = "(function (module, exports, require, print) {"
           + raw.content 
           + "\n});";
-
+  
   f = SYS_EXECUTE(content, undefined, path);
 
   if (f === undefined) {
     throw "cannot create context function";
   }
-
-  f(module,
-    module.exports,
-    function(path) { return module.require(path); },
-    ModuleCache["/internal"].exports.print);
+ 
+  try {
+    f(module,
+      module.exports,
+      function(path) { return module.require(path); },
+      ModuleCache["/internal"].exports.print);
+  }
+  catch (err) {
+    throw "Javascript exception in file '" + path + "': " + err.stack;
+  }
 
   return module.exports;
 };

lib/V8/v8-utils.cpp

@@ -430,7 +430,7 @@ static bool LoadJavaScriptFile (v8::Handle<v8::Context> context,
   char* content = TRI_SlurpFile(TRI_UNKNOWN_MEM_ZONE, filename);
 
   if (content == 0) {
-    LOG_TRACE("cannot loaded java script file '%s': %s", filename, TRI_last_error());
+    LOG_TRACE("cannot load java script file '%s': %s", filename, TRI_last_error());
     return false;
   }
 
@@ -529,6 +529,54 @@ static bool LoadJavaScriptDirectory (v8::Handle<v8::Context> context, char const
 /// @{
 ////////////////////////////////////////////////////////////////////////////////
 
+////////////////////////////////////////////////////////////////////////////////
+/// @brief parse a Javascript snippet, but do not execute it
+///
+/// @FUN{internal.parse(@FA{script})}
+///
+/// Parses the @FA{script} code, but does not execute it.
+/// Will return @LIT{true} if the code does not have a parse error, and throw
+/// an exception otherwise.
+////////////////////////////////////////////////////////////////////////////////
+
+static v8::Handle<v8::Value> JS_Parse (v8::Arguments const& argv) {
+  v8::HandleScope scope;
+  v8::TryCatch tryCatch;
+
+  if (argv.Length() < 1) {
+    return scope.Close(v8::ThrowException(v8::String::New("usage: parse(<script>)")));
+  }
+  
+  v8::Handle<v8::Value> source = argv[0];
+  v8::Handle<v8::Value> filename;
+
+  if (argv.Length() > 1) {
+    filename = argv[1];
+  }
+  else {
+    filename = v8::String::New("(snippet)");
+  }
+  
+  if (! source->IsString()) {
+    return scope.Close(v8::ThrowException(v8::String::New("<script> must be a string")));
+  }
+
+  v8::Handle<v8::Script> script = v8::Script::Compile(source->ToString(), filename);
+
+  // compilation failed, we have caught an exception
+  if (tryCatch.HasCaught()) {
+    string err = TRI_StringifyV8Exception(&tryCatch);
+    return scope.Close(v8::ThrowException(v8::String::New(err.c_str())));
+  }
+  
+  // compilation failed, we don't know why
+  if (script.IsEmpty()) {
+    return scope.Close(v8::False());
+  }
+
+  return scope.Close(v8::True());
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 /// @brief executes a script
 ///
@@ -558,7 +606,7 @@ static v8::Handle<v8::Value> JS_Execute (v8::Arguments const& argv) {
   if (! source->IsString()) {
     return scope.Close(v8::ThrowException(v8::String::New("<script> must be a string")));
   }
-
+  
   bool useSandbox = sandboxValue->IsObject();
   v8::Handle<v8::Object> sandbox;
   v8::Handle<v8::Context> context;
@@ -602,7 +650,7 @@ static v8::Handle<v8::Value> JS_Execute (v8::Arguments const& argv) {
       context->DetachGlobal();
       context->Exit();
     }
-
+  
     return scope.Close(v8::Undefined());
   }
 
@@ -1600,6 +1648,10 @@ void TRI_InitV8Utils (v8::Handle<v8::Context> context, string const& path) {
   // .............................................................................
   // create the global functions
   // .............................................................................
+  
+  context->Global()->Set(v8::String::New("SYS_PARSE"),
+                         v8::FunctionTemplate::New(JS_Parse)->GetFunction(),
+                         v8::ReadOnly);
 
   context->Global()->Set(v8::String::New("SYS_EXECUTE"),
                          v8::FunctionTemplate::New(JS_Execute)->GetFunction(),