Scope tree serialization and ScopeIterator cleanup.

src/scopeinfo.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 13 matching lines @@
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #ifndef V8_SCOPEINFO_H_
 #define V8_SCOPEINFO_H_
 
 #include "allocation.h"
 #include "variables.h"
 #include "zone-inl.h"
+#include "scopes.h"

[Kevin Millikin (Chromium), 2011/10/05 08:43:36]

Maybe we should avoid this?  It's not yet a circularity, but it risks one and
they cause us a lot of headaches.  The Scope and ScopeInfo are almost
independent except for this enum.  I think I'd rather have a ScopeType with all
the other enums in v8globals.h so the classes are not coupled (unless you can
convince me otherwise :))

[Steven, 2011/10/06 19:09:27]

Yes, I totally agree.
On 2011/10/05 08:43:36, Kevin Millikin wrote:

 
 namespace v8 {
 namespace internal {
 
 // Scope information represents information about a functions's

[Kevin Millikin (Chromium), 2011/10/05 08:43:36]

This comment seems out of date.  And the Historical note is unnecessary (and not
entirely true).

[Steven, 2011/10/06 19:09:27]

Done. But could use more love when cleaning up ScopeInfo/SerializedScopeInfo.
On 2011/10/05 08:43:36, Kevin Millikin wrote:

 // scopes (currently only one, because we don't do any inlining)
 // and the allocation of the scope's variables. Scope information
 // is stored in a compressed form in FixedArray objects and is used
 // at runtime (stack dumps, deoptimization, etc.).
 //
 // Historical note: In other VMs built by this team, ScopeInfo was
 // usually called DebugInfo since the information was used (among
 // other things) for on-demand debugging (Self, Smalltalk). However,
 // DebugInfo seems misleading, since this information is primarily used
 // in debugging-unrelated contexts.
@@ skipping 27 matching lines @@
     return context_slots_[i - Context::MIN_CONTEXT_SLOTS];
   }
   int number_of_context_slots() const {
     int l = context_slots_.length();
     return l == 0 ? 0 : l + Context::MIN_CONTEXT_SLOTS;
   }
 
   Handle<String> LocalName(int i) const;
   int NumberOfLocals() const;
 
+  Scope::Type type() const { return type_; }
+  int SourceBegStatementPos() const { return source_beg_statement_pos_; }
+  int SourceEndStatementPos() const { return source_end_statement_pos_; }
+
   // --------------------------------------------------------------------------
   // Debugging support
 
 #ifdef DEBUG
   void Print();
 #endif
 
  private:
   Handle<String> function_name_;
   bool calls_eval_;
   bool is_strict_mode_;
+  Scope::Type type_;
+  int source_beg_statement_pos_;
+  int source_end_statement_pos_;
   List<Handle<String>, Allocator > parameters_;
   List<Handle<String>, Allocator > stack_slots_;
   List<Handle<String>, Allocator > context_slots_;
   List<Variable::Mode, Allocator > context_modes_;
+  List<Handle<SerializedScopeInfo>, Allocator> inner_scopeinfos_;
 };
 
 
 // This object provides quick access to scope info details for runtime
 // routines w/o the need to explicitly create a ScopeInfo object.
 class SerializedScopeInfo : public FixedArray {
  public :
 
   static SerializedScopeInfo* cast(Object* object) {
     ASSERT(object->IsSerializedScopeInfo());
     return reinterpret_cast<SerializedScopeInfo*>(object);
   }
 
+  // Return the type of this scope.
+  Scope::Type ScopeType();
+
   // Does this scope call eval?
   bool CallsEval();
 
   // Is this scope a strict mode scope?
   bool IsStrictMode();
 
+  // Start position of this scope in the source string.

[Kevin Millikin (Chromium), 2011/10/05 08:43:36]

I think we want a crisp characterization of start and end positions, either as a
comment in the scopes or in the parser where we set it, or both.  Is it the
position of the curly brace?  Of the first/last character inside the curlies?

[Steven, 2011/10/06 19:09:27]

Added a description to scopes.h. PTAL there.
On 2011/10/05 08:43:36, Kevin Millikin wrote:

+  int SourceBegStatementPos();
+
+  // End position of this scope in the source string.
+  int SourceEndStatementPos();
+
   // Return the number of stack slots for code.
   int NumberOfStackSlots();
 
   // Return the number of context slots for code.
   int NumberOfContextSlots();
 
+  // Return the number of immediate nested scopes.
+  int NumberOfNestedScopes();
+
+  // Lookup an immediate nested scope by its index.
+  Handle<SerializedScopeInfo> NestedScope(int i);
+
   // Return if this has context slots besides MIN_CONTEXT_SLOTS;
   bool HasHeapAllocatedLocals();
 
+  // Return if contexts are allocated for this scope.
+  bool HasContext();
+
   // Lookup support for serialized scope info. Returns the
   // the stack slot index for a given slot name if the slot is
   // present; otherwise returns a value < 0. The name must be a symbol
   // (canonicalized).
   int StackSlotIndex(String* name);
 
   // Lookup support for serialized scope info. Returns the
   // context slot index for a given slot name if the slot is present; otherwise
   // returns a value < 0. The name must be a symbol (canonicalized).
   // If the slot is present and mode != NULL, sets *mode to the corresponding
   // mode for that variable.
   int ContextSlotIndex(String* name, Variable::Mode* mode);
 
   // Lookup support for serialized scope info. Returns the
   // parameter index for a given parameter name if the parameter is present;
   // otherwise returns a value < 0. The name must be a symbol (canonicalized).
   int ParameterIndex(String* name);
 
   // Lookup support for serialized scope info. Returns the
   // function context slot index if the function name is present (named
   // function expressions, only), otherwise returns a value < 0. The name
   // must be a symbol (canonicalized).
   int FunctionContextSlotIndex(String* name);
 
+  // Get the chain of nested scopes within this scope for the source statement
+  // position. The scopes will be added to the list from the outermost scope to
+  // the innermost scope. Only nested block, catch or with scopes are tracked
+  // and will be returned, but no inner function scopes.
+  void GetNestedScopeChain(List<Handle<SerializedScopeInfo> >* chain,
+                           int statement_position);
+
   static Handle<SerializedScopeInfo> Create(Scope* scope);
 
   // Serializes empty scope info.
   static SerializedScopeInfo* Empty();
 
  private:
   inline Object** ContextEntriesAddr();
 
   inline Object** ParameterEntriesAddr();
 
   inline Object** StackSlotEntriesAddr();
+
+  inline Object** NestedScopeEntriesAddr();
 };
 
 
 // Cache for mapping (data, property name) into context slot index.
 // The cache contains both positive and negative results.
 // Slot index equals -1 means the property is absent.
 // Cleared at startup and prior to mark sweep collection.
 class ContextSlotCache {
  public:
   // Lookup context slot index for (data, name).
@@ skipping 66 matching lines @@
   uint32_t values_[kLength];
 
   friend class Isolate;
   DISALLOW_COPY_AND_ASSIGN(ContextSlotCache);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_SCOPEINFO_H_