Introduce CodeSourceMap object to hold pc -> token position mappings

runtime/vm/code_descriptors.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_CODE_DESCRIPTORS_H_
 #define VM_CODE_DESCRIPTORS_H_
 
 #include "vm/ast.h"
 #include "vm/code_generator.h"
 #include "vm/globals.h"
@@ skipping 24 matching lines @@
   GrowableArray<uint8_t> encoded_data_;
 
   intptr_t prev_pc_offset;
   intptr_t prev_deopt_id;
   intptr_t prev_token_pos;
 
   DISALLOW_COPY_AND_ASSIGN(DescriptorList);
 };
 
 
+class CodeSourceMapBuilder : public ZoneAllocated {
+ public:
+  explicit CodeSourceMapBuilder(intptr_t initial_capacity = 64)
+    : encoded_data_(initial_capacity),
+      prev_pc_offset(0),
+      prev_token_pos(0) {}
+
+  ~CodeSourceMapBuilder() { }
+
+  void AddEntry(intptr_t pc_offset, intptr_t token_pos);
+
+  RawCodeSourceMap* Finalize();
+
+ private:
+  GrowableArray<uint8_t> encoded_data_;
+
+  intptr_t prev_pc_offset;
+  intptr_t prev_token_pos;
+
+  DISALLOW_COPY_AND_ASSIGN(CodeSourceMapBuilder);
+};
+
+
 class StackmapTableBuilder : public ZoneAllocated {
  public:
   StackmapTableBuilder()
       : stack_map_(Stackmap::ZoneHandle()),
         list_(GrowableObjectArray::ZoneHandle(
             GrowableObjectArray::New(Heap::kOld))) { }
   ~StackmapTableBuilder() { }
 
   void AddEntry(intptr_t pc_offset,
                 BitmapBuilder* bitmap,
@@ skipping 81 matching lines @@
   RawExceptionHandlers* FinalizeExceptionHandlers(uword entry_point) const;
 
  private:
   GrowableArray<struct HandlerDesc> list_;
   DISALLOW_COPY_AND_ASSIGN(ExceptionHandlerList);
 };
 
 }  // namespace dart
 
 #endif  // VM_CODE_DESCRIPTORS_H_