Refactor script position calculation

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index 9d3511327e63dd8592c2a33f296e6cc0308d748b..066261b52b21447a1967d30197939cf8732d04ae 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -551,28 +551,16 @@ class CaptureStackTraceHelper {
     Handle<Script> script(Script::cast(fun->shared()->script()));
 
     if (!line_key_.is_null()) {
-      int script_line_offset = script->line_offset();
-      int line_number = Script::GetLineNumber(script, position);
-      // line_number is already shifted by the script_line_offset.
-      int relative_line_number = line_number - script_line_offset;
-      if (!column_key_.is_null() && relative_line_number >= 0) {
-        Handle<FixedArray> line_ends(FixedArray::cast(script->line_ends()));
-        int start =
-            (relative_line_number == 0)
-                ? 0
-                : Smi::cast(line_ends->get(relative_line_number - 1))->value() +
-                      1;
-        int column_offset = position - start;
-        if (relative_line_number == 0) {
-          // For the case where the code is on the same line as the script tag.
-          column_offset += script->column_offset();
-        }
+      Script::PositionInfo info;
+      bool valid_pos = Script::GetPositionInfo(script, position, &info, true);

[Yang, 2016/05/18 13:23:08]

Can we pass an enum value instead of true/false? That would be a lot easier to
read at the call site.

[jgruber1, 2016/05/19 08:05:24]

Good point. Is there an easy way to define an enum visible from both JS and C++
sides? Messages seems to have something like this, but they define it in
include/v8.h.

[jgruber1, 2016/05/19 08:56:01]

And done, using the enum on C++ side only.

+
+      if (!column_key_.is_null() && valid_pos) {
         JSObject::AddProperty(stack_frame, column_key_,
-                              handle(Smi::FromInt(column_offset + 1), isolate_),
+                              handle(Smi::FromInt(info.column + 1), isolate_),
                               NONE);
       }
       JSObject::AddProperty(stack_frame, line_key_,
-                            handle(Smi::FromInt(line_number + 1), isolate_),
+                            handle(Smi::FromInt(info.line + 1), isolate_),
                             NONE);
     }