[inspector] added Debugger.getPossibleBreakpoints method

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index b7a5b2e4ec45e1642a6ad578e9f98604f490d806..5059d0a0b9e55c7198585e872905cb3136eb8052 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -8926,6 +8926,80 @@ MaybeLocal<String> DebugInterface::Script::Source() const {
       handle_scope.CloseAndEscape(i::Handle<i::String>::cast(value)));
 }
 
+namespace {
+int GetSmiValue(i::Isolate* isolate, i::Handle<i::FixedArray> array,
+                int index) {
+  return array->GetValueChecked<i::Smi>(isolate, index)->value();

[Yang, 2016/11/04 12:22:58]

Let's just use Smi::cast(array->get(index))->value()

[kozy, 2016/11/04 14:48:38]

Done.

+}
+}  // namespace
+
+bool DebugInterface::Script::GetPossibleBreakpoints(
+    const Location& start, const Location& end,

[Yang, 2016/11/04 12:22:58]

Is this location with or without the line_offset and column_offset? If I'm not
mistaken, the line_ends array operates without offsets.

[kozy, 2016/11/04 14:48:38]

This Location contains line_offset and column_offset in source, we addressed all
location this way in inspector. To convert it to offset I use
DebugInterface::Script::GetSourcePosition using line endings.

[Yang, 2016/11/04 14:53:00]

yes, but arent line_ends initialized without offset? so the conversion is wrong?

[kozy, 2016/11/04 15:04:01]

As I found line_ends contains offset of \n in source as just offset with offset
of EOF.
In case of:
var a = 1;\n
var b = 2;\n

It will be something like [ 11, 23, 24 ].

Test that is added in this CL cover all branches in conversion and I think it's
right, but maybe I'm still misunderstanding something.

+    std::vector<Location>* locations) const {
+  CHECK(!start.IsEmpty());
+  i::Handle<i::Script> script = Utils::OpenHandle(this);
+
+  i::Script::InitLineEnds(script);
+  CHECK(script->line_ends()->IsFixedArray());
+  i::Isolate* isolate = script->GetIsolate();
+  i::Handle<i::FixedArray> line_ends =
+      i::Handle<i::FixedArray>::cast(i::handle(script->line_ends(), isolate));
+  CHECK(line_ends->length());
+
+  int start_offset = GetSourcePosition(start);
+  int end_offset;
+  if (end.IsEmpty())

[Yang, 2016/11/04 12:22:58]

can we have brackets around the then-body and the else-body?

[kozy, 2016/11/04 14:48:38]

Done.

+    end_offset = GetSmiValue(isolate, line_ends, line_ends->length() - 1) + 1;
+  else
+    end_offset = GetSourcePosition(end);
+  if (start_offset >= end_offset) return true;
+
+  std::vector<int> offsets;

[Yang, 2016/11/04 12:22:58]

why don't we pass an std::set to GetPossibleBreakpoints directly?

[kozy, 2016/11/04 14:48:38]

Done.

+  if (!isolate->debug()->GetPossibleBreakpoints(script, start_offset,
+                                                end_offset, &offsets)) {
+    return false;
+  }
+  std::set<int> unique_offsets;
+  for (size_t i = 0; i < offsets.size(); ++i) unique_offsets.insert(offsets[i]);
+
+  int current_line_end_index = 0;
+  for (const auto& it : unique_offsets) {
+    int offset = it;
+    while (offset > GetSmiValue(isolate, line_ends, current_line_end_index)) {
+      ++current_line_end_index;
+      CHECK(current_line_end_index < line_ends->length());
+    }
+    int line_offset = 0;
+
+    if (current_line_end_index > 0) {
+      line_offset =
+          GetSmiValue(isolate, line_ends, current_line_end_index - 1) + 1;
+    }
+    locations->push_back(
+        Location(current_line_end_index, offset - line_offset));
+  }
+  return true;
+}
+
+int DebugInterface::Script::GetSourcePosition(const Location& location) const {
+  int line = location.GetLineNumber();
+  int column = location.GetColumnNumber();
+
+  i::Handle<i::Script> script = Utils::OpenHandle(this);
+  i::Script::InitLineEnds(script);
+  CHECK(script->line_ends()->IsFixedArray());
+  i::Isolate* isolate = script->GetIsolate();
+  i::Handle<i::FixedArray> line_ends =
+      i::Handle<i::FixedArray>::cast(i::handle(script->line_ends(), isolate));
+  CHECK(line_ends->length());
+  if (line >= line_ends->length())
+    return GetSmiValue(isolate, line_ends, line_ends->length() - 1);
+  int line_offset = GetSmiValue(isolate, line_ends, line);
+  if (line == 0) return std::min(column, line_offset);
+  int prev_line_offset = GetSmiValue(isolate, line_ends, line - 1);
+  return std::min(prev_line_offset + column + 1, line_offset);
+}
+
 MaybeLocal<DebugInterface::Script> DebugInterface::Script::Wrap(
     v8::Isolate* v8_isolate, v8::Local<v8::Object> script) {
   i::Isolate* isolate = reinterpret_cast<i::Isolate*>(v8_isolate);
@@ -8944,6 +9018,28 @@ MaybeLocal<DebugInterface::Script> DebugInterface::Script::Wrap(
       handle_scope.CloseAndEscape(script_obj));
 }
 
+DebugInterface::Location::Location(int lineNumber, int columnNumber)
+    : lineNumber_(lineNumber), columnNumber_(columnNumber) {
+  CHECK(lineNumber >= 0);
+  CHECK(columnNumber >= 0);
+}
+
+DebugInterface::Location::Location() : lineNumber_(-1), columnNumber_(-1) {}
+
+int DebugInterface::Location::GetLineNumber() const {
+  CHECK(lineNumber_ >= 0);
+  return lineNumber_;
+}
+
+int DebugInterface::Location::GetColumnNumber() const {
+  CHECK(columnNumber_ >= 0);
+  return columnNumber_;
+}
+
+bool DebugInterface::Location::IsEmpty() const {
+  return lineNumber_ == -1 && columnNumber_ == -1;
+}
+
 void DebugInterface::GetLoadedScripts(
     v8::Isolate* v8_isolate,
     PersistentValueVector<DebugInterface::Script>& scripts) {