Remove sliced string string type...

src/objects.cc

 // Copyright 2006-2009 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 665 matching lines @@
 Object* String::TryFlatten() {
 #ifdef DEBUG
   // Do not attempt to flatten in debug mode when allocation is not
   // allowed.  This is to avoid an assertion failure when allocating.
   // Flattening strings is the only case where we always allow
   // allocation because no GC is performed if the allocation fails.
   if (!Heap::IsAllocationAllowed()) return this;
 #endif
 
   switch (StringShape(this).representation_tag()) {
-    case kSlicedStringTag: {
-      SlicedString* ss = SlicedString::cast(this);
-      // The SlicedString constructor should ensure that there are no
-      // SlicedStrings that are constructed directly on top of other
-      // SlicedStrings.
-      String* buf = ss->buffer();
-      ASSERT(!buf->IsSlicedString());
-      Object* ok = buf->TryFlatten();
-      if (ok->IsFailure()) return ok;
-      // Under certain circumstances (TryFlattenIfNotFlat fails in
-      // String::Slice) we can have a cons string under a slice.
-      // In this case we need to get the flat string out of the cons!
-      if (StringShape(String::cast(ok)).IsCons()) {
-        ss->set_buffer(ConsString::cast(ok)->first());
-      }
-      return this;
-    }
     case kConsStringTag: {
       ConsString* cs = ConsString::cast(this);
       if (cs->second()->length() == 0) {
         return this;
       }
       // There's little point in putting the flat string in new space if the
       // cons string is in old space.  It can never get GCed until there is
       // an old space GC.
       PretenureFlag tenure = Heap::InNewSpace(this) ? NOT_TENURED : TENURED;
       int len = length();
@@ skipping 415 matching lines @@
                              ObjectVisitor* v) {
   // Avoiding <Type>::cast(this) because it accesses the map pointer field.
   // During GC, the map pointer field is encoded.
   if (type < FIRST_NONSTRING_TYPE) {
     switch (type & kStringRepresentationMask) {
       case kSeqStringTag:
         break;
       case kConsStringTag:
         reinterpret_cast<ConsString*>(this)->ConsStringIterateBody(v);
         break;
-      case kSlicedStringTag:
-        reinterpret_cast<SlicedString*>(this)->SlicedStringIterateBody(v);
-        break;
       case kExternalStringTag:
         if ((type & kStringEncodingMask) == kAsciiStringTag) {
           reinterpret_cast<ExternalAsciiString*>(this)->
               ExternalAsciiStringIterateBody(v);
         } else {
           reinterpret_cast<ExternalTwoByteString*>(this)->
               ExternalTwoByteStringIterateBody(v);
         }
         break;
     }
@@ skipping 2413 matching lines @@
 
 
 Vector<const char> String::ToAsciiVector() {
   ASSERT(IsAsciiRepresentation());
   ASSERT(IsFlat());
 
   int offset = 0;
   int length = this->length();
   StringRepresentationTag string_tag = StringShape(this).representation_tag();
   String* string = this;
-  if (string_tag == kSlicedStringTag) {
-    SlicedString* sliced = SlicedString::cast(string);
-    offset += sliced->start();
-    string = sliced->buffer();
-    string_tag = StringShape(string).representation_tag();
-  } else if (string_tag == kConsStringTag) {
+  if (string_tag == kConsStringTag) {
     ConsString* cons = ConsString::cast(string);
     ASSERT(cons->second()->length() == 0);
     string = cons->first();
     string_tag = StringShape(string).representation_tag();
   }
   if (string_tag == kSeqStringTag) {
     SeqAsciiString* seq = SeqAsciiString::cast(string);
     char* start = seq->GetChars();
     return Vector<const char>(start + offset, length);
   }
   ASSERT(string_tag == kExternalStringTag);
   ExternalAsciiString* ext = ExternalAsciiString::cast(string);
   const char* start = ext->resource()->data();
   return Vector<const char>(start + offset, length);
 }
 
 
 Vector<const uc16> String::ToUC16Vector() {
   ASSERT(IsTwoByteRepresentation());
   ASSERT(IsFlat());
 
   int offset = 0;
   int length = this->length();
   StringRepresentationTag string_tag = StringShape(this).representation_tag();
   String* string = this;
-  if (string_tag == kSlicedStringTag) {
-    SlicedString* sliced = SlicedString::cast(string);
-    offset += sliced->start();
-    string = String::cast(sliced->buffer());
-    string_tag = StringShape(string).representation_tag();
-  } else if (string_tag == kConsStringTag) {
+  if (string_tag == kConsStringTag) {
     ConsString* cons = ConsString::cast(string);
     ASSERT(cons->second()->length() == 0);
     string = cons->first();
     string_tag = StringShape(string).representation_tag();
   }
   if (string_tag == kSeqStringTag) {
     SeqTwoByteString* seq = SeqTwoByteString::cast(string);
     return Vector<const uc16>(seq->GetChars() + offset, length);
   }
   ASSERT(string_tag == kExternalStringTag);
@@ skipping 70 matching lines @@
 
 
 const uc16* String::GetTwoByteData(unsigned start) {
   ASSERT(!IsAsciiRepresentation());
   switch (StringShape(this).representation_tag()) {
     case kSeqStringTag:
       return SeqTwoByteString::cast(this)->SeqTwoByteStringGetData(start);
     case kExternalStringTag:
       return ExternalTwoByteString::cast(this)->
         ExternalTwoByteStringGetData(start);
-    case kSlicedStringTag: {
-      SlicedString* sliced_string = SlicedString::cast(this);
-      String* buffer = sliced_string->buffer();
-      if (StringShape(buffer).IsCons()) {
-        ConsString* cs = ConsString::cast(buffer);
-        // Flattened string.
-        ASSERT(cs->second()->length() == 0);
-        buffer = cs->first();
-      }
-      return buffer->GetTwoByteData(start + sliced_string->start());
-    }
     case kConsStringTag:
       UNREACHABLE();
       return NULL;
   }
   UNREACHABLE();
   return NULL;
 }
 
 
 SmartPointer<uc16> String::ToWideCString(RobustnessFlag robust_flag) {
@@ skipping 134 matching lines @@
           rbb,
           &offset,
           max_chars > rbb->capacity ? rbb->capacity : max_chars);
       *offset_ptr = offset + offset_correction;
       return rbb->util_buffer;
     }
   }
 }
 
 
-const unibrow::byte* SlicedString::SlicedStringReadBlock(ReadBlockBuffer* rbb,
-                                                         unsigned* offset_ptr,
-                                                         unsigned max_chars) {
-  String* backing = buffer();
-  unsigned offset = start() + *offset_ptr;
-  unsigned length = backing->length();
-  if (max_chars > length - offset) {
-    max_chars = length - offset;
-  }
-  const unibrow::byte* answer =
-      String::ReadBlock(backing, rbb, &offset, max_chars);
-  *offset_ptr = offset - start();
-  return answer;
-}
-
-
 uint16_t ExternalAsciiString::ExternalAsciiStringGet(int index) {
   ASSERT(index >= 0 && index < length());
   return resource()->data()[index];
 }
 
 
 const unibrow::byte* ExternalAsciiString::ExternalAsciiStringReadBlock(
       unsigned* remaining,
       unsigned* offset_ptr,
       unsigned max_chars) {
@@ skipping 103 matching lines @@
         SeqTwoByteString* str = SeqTwoByteString::cast(input);
         str->SeqTwoByteStringReadBlockIntoBuffer(rbb,
                                                  offset_ptr,
                                                  max_chars);
         return rbb->util_buffer;
       }
     case kConsStringTag:
       return ConsString::cast(input)->ConsStringReadBlock(rbb,
                                                           offset_ptr,
                                                           max_chars);
-    case kSlicedStringTag:
-      return SlicedString::cast(input)->SlicedStringReadBlock(rbb,
-                                                              offset_ptr,
-                                                              max_chars);
     case kExternalStringTag:
       if (input->IsAsciiRepresentation()) {
         return ExternalAsciiString::cast(input)->ExternalAsciiStringReadBlock(
             &rbb->remaining,
             offset_ptr,
             max_chars);
       } else {
         ExternalTwoByteString::cast(input)->
             ExternalTwoByteStringReadBlockIntoBuffer(rbb,
                                                      offset_ptr,
@@ skipping 122 matching lines @@
         SeqTwoByteString::cast(input)->SeqTwoByteStringReadBlockIntoBuffer(rbb,
                                                                      offset_ptr,
                                                                      max_chars);
         return;
       }
     case kConsStringTag:
       ConsString::cast(input)->ConsStringReadBlockIntoBuffer(rbb,
                                                              offset_ptr,
                                                              max_chars);
       return;
-    case kSlicedStringTag:
-      SlicedString::cast(input)->SlicedStringReadBlockIntoBuffer(rbb,
-                                                                 offset_ptr,
-                                                                 max_chars);
-      return;
     case kExternalStringTag:
       if (input->IsAsciiRepresentation()) {
         ExternalAsciiString::cast(input)->
             ExternalAsciiStringReadBlockIntoBuffer(rbb, offset_ptr, max_chars);
       } else {
         ExternalTwoByteString::cast(input)->
             ExternalTwoByteStringReadBlockIntoBuffer(rbb,
                                                      offset_ptr,
                                                      max_chars);
        }
@@ skipping 94 matching lines @@
         offset_correction += left_length;
         String::ReadBlockIntoBuffer(right, rbb, &offset, max_chars);
       }
       *offset_ptr = offset + offset_correction;
       return;
     }
   }
 }
 
 
-void SlicedString::SlicedStringReadBlockIntoBuffer(ReadBlockBuffer* rbb,
-                                                   unsigned* offset_ptr,
-                                                   unsigned max_chars) {
-  String* backing = buffer();
-  unsigned offset = start() + *offset_ptr;
-  unsigned length = backing->length();
-  if (max_chars > length - offset) {
-    max_chars = length - offset;
-  }
-  String::ReadBlockIntoBuffer(backing, rbb, &offset, max_chars);
-  *offset_ptr = offset - start();
-}
-
-
 void ConsString::ConsStringIterateBody(ObjectVisitor* v) {
   IteratePointers(v, kFirstOffset, kSecondOffset + kPointerSize);
 }
 
 
 void JSGlobalPropertyCell::JSGlobalPropertyCellIterateBody(ObjectVisitor* v) {
   IteratePointers(v, kValueOffset, kValueOffset + kPointerSize);
 }
 
 
@@ skipping 58 matching lines @@
                   SeqAsciiString::cast(source)->GetChars() + from,
                   to - from);
         return;
       }
       case kTwoByteStringTag | kSeqStringTag: {
         CopyChars(sink,
                   SeqTwoByteString::cast(source)->GetChars() + from,
                   to - from);
         return;
       }
-      case kAsciiStringTag | kSlicedStringTag:
-      case kTwoByteStringTag | kSlicedStringTag: {
-        SlicedString* sliced_string = SlicedString::cast(source);
-        int start = sliced_string->start();
-        from += start;
-        to += start;
-        source = String::cast(sliced_string->buffer());
-        break;
-      }
       case kAsciiStringTag | kConsStringTag:
       case kTwoByteStringTag | kConsStringTag: {
         ConsString* cons_string = ConsString::cast(source);
         String* first = cons_string->first();
         int boundary = first->length();
         if (to - boundary >= boundary - from) {
           // Right hand side is longer.  Recurse over left.
           if (from < boundary) {
             WriteToFlat(first, sink, from, boundary);
             sink += boundary - from;
@@ skipping 15 matching lines @@
           }
           source = first;
         }
         break;
       }
     }
   }
 }
 
 
-void SlicedString::SlicedStringIterateBody(ObjectVisitor* v) {
-  IteratePointer(v, kBufferOffset);
-}
-
 #define FIELD_ADDR(p, offset) \
   (reinterpret_cast<byte*>(p) + offset - kHeapObjectTag)
 
 void ExternalAsciiString::ExternalAsciiStringIterateBody(ObjectVisitor* v) {
   typedef v8::String::ExternalAsciiStringResource Resource;
   v->VisitExternalAsciiString(
       reinterpret_cast<Resource**>(FIELD_ADDR(this, kResourceOffset)));
 }
 
 
 void ExternalTwoByteString::ExternalTwoByteStringIterateBody(ObjectVisitor* v) {
   typedef v8::String::ExternalStringResource Resource;
   v->VisitExternalTwoByteString(
       reinterpret_cast<Resource**>(FIELD_ADDR(this, kResourceOffset)));
 }
 
 #undef FIELD_ADDR
 
-uint16_t SlicedString::SlicedStringGet(int index) {
-  ASSERT(index >= 0 && index < this->length());
-  // Delegate to the buffer string.
-  String* underlying = buffer();
-  return underlying->Get(start() + index);
-}
-
-
 template <typename IteratorA, typename IteratorB>
 static inline bool CompareStringContents(IteratorA* ia, IteratorB* ib) {
   // General slow case check.  We know that the ia and ib iterators
   // have the same length.
   while (ia->has_more()) {
     uc32 ca = ia->GetNext();
     uc32 cb = ib->GetNext();
     if (ca != cb)
       return false;
   }
@@ skipping 278 matching lines @@
   // Process the remaining characters without updating the array
   // index.
   while (buffer->has_more()) {
     hasher.AddCharacterNoIndex(buffer->GetNext());
   }
 
   return hasher.GetHashField();
 }
 
 
-Object* String::Slice(int start, int end) {
+Object* String::SubString(int start, int end) {
   if (start == 0 && end == length()) return this;
-  if (StringShape(this).representation_tag() == kSlicedStringTag) {
-    // Translate slices of a SlicedString into slices of the
-    // underlying string buffer.
-    SlicedString* str = SlicedString::cast(this);
-    String* buf = str->buffer();
-    return Heap::AllocateSlicedString(buf,
-                                      str->start() + start,
-                                      str->start() + end);
-  }
-  Object* result = Heap::AllocateSlicedString(this, start, end);
-  if (result->IsFailure()) {
-    return result;
-  }
-  // Due to the way we retry after GC on allocation failure we are not allowed
-  // to fail on allocation after this point.  This is the one-allocation rule.
-
-  // Try to flatten a cons string that is under the sliced string.
-  // This is to avoid memory leaks and possible stack overflows caused by
-  // building 'towers' of sliced strings on cons strings.
-  // This may fail due to an allocation failure (when a GC is needed), but it
-  // will succeed often enough to avoid the problem.  We only have to do this
-  // if Heap::AllocateSlicedString actually returned a SlicedString.  It will
-  // return flat strings for small slices for efficiency reasons.
-  String* answer = String::cast(result);
-  if (StringShape(answer).IsSliced() &&
-      StringShape(this).representation_tag() == kConsStringTag) {
-    TryFlatten();
-    // If the flatten succeeded we might as well make the sliced string point
-    // to the flat string rather than the cons string.
-    String* second = ConsString::cast(this)->second();
-    if (second->length() == 0) {
-      SlicedString::cast(answer)->set_buffer(ConsString::cast(this)->first());
-    }
-  }
-  return answer;
+  Object* result = Heap::AllocateSubString(this, start, end);
+  return result;
 }
 
 
 void String::PrintOn(FILE* file) {
   int length = this->length();
   for (int i = 0; i < length; i++) {
     fprintf(file, "%c", Get(i));
   }
 }
 
@@ skipping 232 matching lines @@
 // without any allocation in the heap.
 void SharedFunctionInfo::SourceCodePrint(StringStream* accumulator,
                                          int max_length) {
   // For some native functions there is no source.
   if (script()->IsUndefined() ||
       Script::cast(script())->source()->IsUndefined()) {
     accumulator->Add("<No Source>");
     return;
   }
 
-  // Get the slice of the source for this function.
+  // Get the source for the script which this function came from.
   // Don't use String::cast because we don't want more assertion errors while
   // we are already creating a stack dump.
   String* script_source =
       reinterpret_cast<String*>(Script::cast(script())->source());
 
   if (!script_source->LooksValid()) {
     accumulator->Add("<Invalid Source>");
     return;
   }
 
@@ skipping 3299 matching lines @@
   if (break_point_objects()->IsUndefined()) return 0;
   // Single beak point.
   if (!break_point_objects()->IsFixedArray()) return 1;
   // Multiple break points.
   return FixedArray::cast(break_point_objects())->length();
 }
 #endif
 
 
 } }  // namespace v8::internal