Debug: support breakpoints set in the middle of statement

src/debug.cc

Index: src/debug.cc
diff --git a/src/debug.cc b/src/debug.cc
index 5d26ba2b139e36fc8704678c4b2c1919b74447a8..de44ff5e3ec6f84004d8a52d29dc3634c72b3aa4 100644
--- a/src/debug.cc
+++ b/src/debug.cc
@@ -235,17 +235,24 @@ void BreakLocationIterator::FindBreakLocationFromAddress(Address pc) {
 
 
 // Find the break point closest to the supplied source position.
-void BreakLocationIterator::FindBreakLocationFromPosition(int position) {
+void BreakLocationIterator::FindBreakLocationFromPosition(int position,
+    bool statement_alighned) {

[Yang, 2013/06/25 11:32:00]

Change variable name to "statement_aligned".

Suggestion: I'd prefer introducing an enum for better redability. Something like

enum PositionAlignment {
  STATEMENT_ALIGNED = 0,
  BREAK_POSITION_ALIGNED = 1
};

The advantage is that the use sites would read like

it.FindBreakLocationFromPosition(
  *source_position, STATEMENT_ALIGNED);

Of course you would have to do that in javascript as well. You could add those
enum values as constants to macros.py.

[Peter.Rybin, 2013/06/27 14:07:29]

I'm fine with this idea. I did JavaScript part as a regular object, like it is
done in debug-debugger.js

Done

   // Run through all break points to locate the one closest to the source
   // position.
   int closest_break_point = 0;
   int distance = kMaxInt;
+
   while (!Done()) {
+    int next_position;
+    if (statement_alighned) {

[Yang, 2013/06/25 11:32:00]

You could use a ternary operator to simplify this
int next_position = statement_aligned ? this->statement_position()
                                      : this->position();

[Peter.Rybin, 2013/06/27 14:07:29]

I guess with enum I should do switch? Or is it too long?

+      next_position = this->statement_position();
+    } else {
+      next_position = this->position();
+    }
     // Check if this break point is closer that what was previously found.
-    if (position <= statement_position() &&
-        statement_position() - position < distance) {
+    if (position <= next_position && next_position - position < distance) {
       closest_break_point = break_point();
-      distance = statement_position() - position;
+      distance = next_position - position;
       // Check whether we can't get any closer.
       if (distance == 0) break;
     }
@@ -1176,7 +1183,7 @@ void Debug::SetBreakPoint(Handle<JSFunction> function,
 
   // Find the break point and change it.
   BreakLocationIterator it(debug_info, SOURCE_BREAK_LOCATIONS);
-  it.FindBreakLocationFromPosition(*source_position);
+  it.FindBreakLocationFromPosition(*source_position, true);
   it.SetBreakPoint(break_point_object);
 
   *source_position = it.position();
@@ -1188,7 +1195,8 @@ void Debug::SetBreakPoint(Handle<JSFunction> function,
 
 bool Debug::SetBreakPointForScript(Handle<Script> script,
                                    Handle<Object> break_point_object,
-                                   int* source_position) {
+                                   int* source_position,
+                                   bool statement_alighned) {

[Yang, 2013/06/25 11:32:00]

Ditto.

[Peter.Rybin, 2013/06/27 14:07:29]

Done.

   HandleScope scope(isolate_);
 
   PrepareForBreakPoints();
@@ -1219,7 +1227,7 @@ bool Debug::SetBreakPointForScript(Handle<Script> script,
 
   // Find the break point and change it.
   BreakLocationIterator it(debug_info, SOURCE_BREAK_LOCATIONS);
-  it.FindBreakLocationFromPosition(position);
+  it.FindBreakLocationFromPosition(position, statement_alighned);
   it.SetBreakPoint(break_point_object);
 
   *source_position = it.position() + shared->start_position();