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1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 #ifndef CHROME_BROWSER_SYNC_SYNCABLE_SYNCABLE_ID_H_
6 #define CHROME_BROWSER_SYNC_SYNCABLE_SYNCABLE_ID_H_
7 #pragma once
8 
9 #include <iosfwd>
10 #include <limits>
11 #include <sstream>
12 #include <string>
13 
14 #include "base/hash_tables.h"
15 
16 class StringValue;
17 
18 namespace syncable {
19 struct EntryKernel;
20 class Id;
21 }
22 
23 class MockConnectionManager;
24 class SQLStatement;
25 
26 namespace syncable {
27 
28 std::ostream& operator<<(std::ostream& out, const Id& id);
29 
30 // For historical reasons, 3 concepts got everloaded into the Id:
31 // 1. A unique, opaque identifier for the object.
32 // 2. Flag specifing whether server know about this object.
33 // 3. Flag for root.
34 //
35 // We originally wrapped an integer for this information, but now we use a
36 // string. It will have one of three forms:
37 // 1. c<client only opaque id> for client items that have not been committed.
38 // 2. r for the root item.
39 // 3. s<server provided opaque id> for items that the server knows about.
40 class Id {
41   friend int UnpackEntry(SQLStatement* statement,
42                          syncable::EntryKernel** kernel);
43   friend int BindFields(const EntryKernel& entry, SQLStatement* statement);
44   friend std::ostream& operator<<(std::ostream& out, const Id& id);
45   friend class MockConnectionManager;
46   friend class SyncableIdTest;
47  public:
48   // This constructor will be handy even when we move away from int64s, just
49   // for unit tests.
Id()50   inline Id() : s_("r") { }
Id(const Id & that)51   inline Id(const Id& that) {
52     Copy(that);
53   }
54   inline Id& operator = (const Id& that) {
55     Copy(that);
56     return *this;
57   }
Copy(const Id & that)58   inline void Copy(const Id& that) {
59     this->s_ = that.s_;
60   }
IsRoot()61   inline bool IsRoot() const {
62     return "r" == s_;
63   }
ServerKnows()64   inline bool ServerKnows() const {
65     return s_[0] == 's' || s_ == "r";
66   }
67 
68   // TODO(sync): We could use null here, but to ease conversion we use "r".
69   // fix this, this is madness :)
IsNull()70   inline bool IsNull() const {
71     return IsRoot();
72   }
Clear()73   inline void Clear() {
74     s_ = "r";
75   }
compare(const Id & that)76   inline int compare(const Id& that) const {
77     return s_.compare(that.s_);
78   }
79   inline bool operator == (const Id& that) const {
80     return s_ == that.s_;
81   }
82   inline bool operator != (const Id& that) const {
83     return s_ != that.s_;
84   }
85   inline bool operator < (const Id& that) const {
86     return s_ < that.s_;
87   }
88   inline bool operator > (const Id& that) const {
89     return s_ > that.s_;
90   }
91   // Return the next highest ID in the lexicographic ordering.  This is
92   // useful for computing upper bounds on std::sets that are ordered
93   // by operator<.
94   Id GetLexicographicSuccessor() const;
95 
96   // Dumps the ID as a value and returns it.  Transfers ownership of
97   // the StringValue to the caller.
98   StringValue* ToValue() const;
99 
100   // Three functions are used to work with our proto buffers.
101   std::string GetServerId() const;
102   static Id CreateFromServerId(const std::string& server_id);
103   // This should only be used if you get back a reference to a local
104   // id from the server. Returns a client only opaque id.
105   static Id CreateFromClientString(const std::string& local_id);
106 
107   // This method returns an ID that will compare less than any valid ID.
108   // The returned ID is not a valid ID itself.  This is useful for
109   // computing lower bounds on std::sets that are ordered by operator<.
110   static Id GetLeastIdForLexicographicComparison();
111 
112  private:
113   std::string s_;
114 };
115 
116 extern const Id kNullId;
117 
118 }  // namespace syncable
119 
120 #endif  // CHROME_BROWSER_SYNC_SYNCABLE_SYNCABLE_ID_H_
121