Tweak D8 remote debugger

When D8 is used as remote debugger the command 'break' (shorthand 'b') can be used to break JavaScript execution.

Fixed the printing of the prompt 'dbg>' and printing of error messages.
Review URL: http://codereview.chromium.org/1566049

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4437 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/d8-debug.cc

@@ -34,6 +34,11 @@
 
 namespace v8 {
 
+void PrintPrompt() {
+  printf("dbg> ");
+  fflush(stdout);
+}
+
 
 void HandleDebugEvent(DebugEvent event,
                       Handle<Object> exec_state,
@@ -86,7 +91,7 @@ void HandleDebugEvent(DebugEvent event,
   bool running = false;
   while (!running) {
     char command[kBufferSize];
-    printf("dbg> ");
+    PrintPrompt();
     char* str = fgets(command, kBufferSize, stdin);
     if (str == NULL) break;
 
@@ -178,6 +183,7 @@ void RemoteDebugger::Run() {
   // Start the keyboard thread.
   KeyboardThread keyboard(this);
   keyboard.Start();
+  PrintPrompt();
 
   // Process events received from debugged VM and from the keyboard.
   bool terminate = false;
@@ -264,7 +270,8 @@ void RemoteDebugger::HandleMessageReceived(char* message) {
   Handle<Object> details =
       Shell::DebugMessageDetails(Handle<String>::Cast(String::New(message)));
   if (try_catch.HasCaught()) {
-      Shell::ReportException(&try_catch);
+    Shell::ReportException(&try_catch);
+    PrintPrompt();
     return;
   }
   String::Utf8Value str(details->Get(String::New("text")));
@@ -277,7 +284,7 @@ void RemoteDebugger::HandleMessageReceived(char* message) {
   } else {
     printf("???\n");
   }
-  printf("dbg> ");
+  PrintPrompt();
 }
 
 
@@ -289,13 +296,17 @@ void RemoteDebugger::HandleKeyboardCommand(char* command) {
   Handle<Value> request =
       Shell::DebugCommandToJSONRequest(String::New(command));
   if (try_catch.HasCaught()) {
-    Shell::ReportException(&try_catch);
+    v8::String::Utf8Value exception(try_catch.Exception());
+    const char* exception_string = Shell::ToCString(exception);
+    printf("%s\n", exception_string);
+    PrintPrompt();
     return;
   }
 
   // If undefined is returned the command was handled internally and there is
   // no JSON to send.
   if (request->IsUndefined()) {
+    PrintPrompt();
     return;
   }
 

src/d8.cc

@@ -102,7 +102,7 @@ bool CounterMap::Match(void* key1, void* key2) {
 
 
 // Converts a V8 value to a C string.
-const char* ToCString(const v8::String::Utf8Value& value) {
+const char* Shell::ToCString(const v8::String::Utf8Value& value) {
   return *value ? *value : "<string conversion failed>";
 }
 

src/d8.h

@@ -117,6 +117,7 @@ class Shell: public i::AllStatic {
                             Handle<Value> name,
                             bool print_result,
                             bool report_exceptions);
+  static const char* ToCString(const v8::String::Utf8Value& value);
   static void ReportException(TryCatch* try_catch);
   static void Initialize();
   static void OnExit();

src/d8.js

@@ -715,8 +715,6 @@ DebugRequest.prototype.scriptsCommandToJSONRequest_ = function(args) {
 // Create a JSON request for the break command.
 DebugRequest.prototype.breakCommandToJSONRequest_ = function(args) {
   // Build a evaluate request from the text command.
-  var request = this.createRequest('setbreakpoint');
-
   // Process arguments if any.
   if (args && args.length > 0) {
     var target = args;
@@ -726,6 +724,8 @@ DebugRequest.prototype.breakCommandToJSONRequest_ = function(args) {
     var condition;
     var pos;
 
+    var request = this.createRequest('setbreakpoint');
+
     // Check for breakpoint condition.
     pos = args.indexOf(' ');
     if (pos > 0) {
@@ -763,7 +763,7 @@ DebugRequest.prototype.breakCommandToJSONRequest_ = function(args) {
     request.arguments.column = column;
     request.arguments.condition = condition;
   } else {
-    throw new Error('Invalid break arguments.');
+    var request = this.createRequest('suspend');
   }
 
   return request.toJSONProtocol();
@@ -817,6 +817,7 @@ DebugRequest.prototype.helpCommand_ = function(args) {
     print('warning: arguments to \'help\' are ignored');
   }
 
+  print('break');
   print('break location [condition]');
   print('  break on named function: location is a function name');
   print('  break on function: location is #<id>#');
@@ -931,6 +932,10 @@ function DebugResponseDetails(response) {
     var body = response.body();
     var result = '';
     switch (response.command()) {
+      case 'suspend':
+        details.text = 'stopped';
+        break;
+        
       case 'setbreakpoint':
         result = 'set breakpoint #';
         result += body.breakpoint;