1// Copyright 2012 the V8 project authors. All rights reserved.
2// Redistribution and use in source and binary forms, with or without
3// modification, are permitted provided that the following conditions are
4// met:
5//
6//     * Redistributions of source code must retain the above copyright
7//       notice, this list of conditions and the following disclaimer.
8//     * Redistributions in binary form must reproduce the above
9//       copyright notice, this list of conditions and the following
10//       disclaimer in the documentation and/or other materials provided
11//       with the distribution.
12//     * Neither the name of Google Inc. nor the names of its
13//       contributors may be used to endorse or promote products derived
14//       from this software without specific prior written permission.
15//
16// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27
28#ifndef V8_PROPERTY_DETAILS_H_
29#define V8_PROPERTY_DETAILS_H_
30
31#include "../include/v8.h"
32#include "allocation.h"
33#include "utils.h"
34
35// Ecma-262 3rd 8.6.1
36enum PropertyAttributes {
37  NONE              = v8::None,
38  READ_ONLY         = v8::ReadOnly,
39  DONT_ENUM         = v8::DontEnum,
40  DONT_DELETE       = v8::DontDelete,
41  ABSENT            = 16  // Used in runtime to indicate a property is absent.
42  // ABSENT can never be stored in or returned from a descriptor's attributes
43  // bitfield.  It is only used as a return value meaning the attributes of
44  // a non-existent property.
45};
46
47
48namespace v8 {
49namespace internal {
50
51class Smi;
52
53// Type of properties.
54// Order of properties is significant.
55// Must fit in the BitField PropertyDetails::TypeField.
56// A copy of this is in mirror-debugger.js.
57enum PropertyType {
58  NORMAL                    = 0,  // only in slow mode
59  FIELD                     = 1,  // only in fast mode
60  CONSTANT_FUNCTION         = 2,  // only in fast mode
61  CALLBACKS                 = 3,
62  HANDLER                   = 4,  // only in lookup results, not in descriptors
63  INTERCEPTOR               = 5,  // only in lookup results, not in descriptors
64  // All properties before MAP_TRANSITION are real.
65  MAP_TRANSITION            = 6,  // only in fast mode
66  ELEMENTS_TRANSITION       = 7,
67  CONSTANT_TRANSITION       = 8,  // only in fast mode
68  NULL_DESCRIPTOR           = 9,  // only in fast mode
69  // There are no IC stubs for NULL_DESCRIPTORS. Therefore,
70  // NULL_DESCRIPTOR can be used as the type flag for IC stubs for
71  // nonexistent properties.
72  NONEXISTENT = NULL_DESCRIPTOR
73};
74
75
76// PropertyDetails captures type and attributes for a property.
77// They are used both in property dictionaries and instance descriptors.
78class PropertyDetails BASE_EMBEDDED {
79 public:
80  PropertyDetails(PropertyAttributes attributes,
81                  PropertyType type,
82                  int index = 0) {
83    ASSERT(TypeField::is_valid(type));
84    ASSERT(AttributesField::is_valid(attributes));
85    ASSERT(StorageField::is_valid(index));
86
87    value_ = TypeField::encode(type)
88        | AttributesField::encode(attributes)
89        | StorageField::encode(index);
90
91    ASSERT(type == this->type());
92    ASSERT(attributes == this->attributes());
93    ASSERT(index == this->index());
94  }
95
96  // Conversion for storing details as Object*.
97  explicit inline PropertyDetails(Smi* smi);
98  inline Smi* AsSmi();
99
100  PropertyType type() { return TypeField::decode(value_); }
101
102  PropertyAttributes attributes() { return AttributesField::decode(value_); }
103
104  int index() { return StorageField::decode(value_); }
105
106  inline PropertyDetails AsDeleted();
107
108  static bool IsValidIndex(int index) {
109    return StorageField::is_valid(index);
110  }
111
112  bool IsReadOnly() { return (attributes() & READ_ONLY) != 0; }
113  bool IsDontDelete() { return (attributes() & DONT_DELETE) != 0; }
114  bool IsDontEnum() { return (attributes() & DONT_ENUM) != 0; }
115  bool IsDeleted() { return DeletedField::decode(value_) != 0;}
116
117  // Bit fields in value_ (type, shift, size). Must be public so the
118  // constants can be embedded in generated code.
119  class TypeField:       public BitField<PropertyType,       0, 4> {};
120  class AttributesField: public BitField<PropertyAttributes, 4, 3> {};
121  class DeletedField:    public BitField<uint32_t,           7, 1> {};
122  class StorageField:    public BitField<uint32_t,           8, 32-8> {};
123
124  static const int kInitialIndex = 1;
125
126 private:
127  uint32_t value_;
128};
129
130} }  // namespace v8::internal
131
132#endif  // V8_PROPERTY_DETAILS_H_
133