1 // Copyright 2012 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 SYNC_SYNCABLE_SYNCABLE_ID_H_ 6 #define SYNC_SYNCABLE_SYNCABLE_ID_H_ 7 8 #include <iosfwd> 9 #include <limits> 10 #include <sstream> 11 #include <string> 12 13 #include "base/containers/hash_tables.h" 14 #include "base/memory/scoped_ptr.h" 15 #include "sync/base/sync_export.h" 16 17 class MockConnectionManager; 18 19 namespace base { 20 class StringValue; 21 } 22 23 namespace sql { 24 class Statement; 25 } 26 27 namespace syncer { 28 namespace syncable { 29 struct EntryKernel; 30 class Id; 31 32 SYNC_EXPORT_PRIVATE std::ostream& operator<<(std::ostream& out, const Id& id); 33 34 // For historical reasons, 3 concepts got everloaded into the Id: 35 // 1. A unique, opaque identifier for the object. 36 // 2. Flag specifing whether server know about this object. 37 // 3. Flag for root. 38 // 39 // We originally wrapped an integer for this information, but now we use a 40 // string. It will have one of three forms: 41 // 1. c<client only opaque id> for client items that have not been committed. 42 // 2. r for the root item. 43 // 3. s<server provided opaque id> for items that the server knows about. 44 class SYNC_EXPORT Id { 45 public: 46 // This constructor will be handy even when we move away from int64s, just 47 // for unit tests. Id()48 inline Id() : s_("r") { } Id(const Id & that)49 inline Id(const Id& that) { 50 Copy(that); 51 } 52 inline Id& operator = (const Id& that) { 53 Copy(that); 54 return *this; 55 } Copy(const Id & that)56 inline void Copy(const Id& that) { 57 this->s_ = that.s_; 58 } IsRoot()59 inline bool IsRoot() const { 60 return "r" == s_; 61 } ServerKnows()62 inline bool ServerKnows() const { 63 return s_[0] == 's' || s_ == "r"; 64 } 65 66 // TODO(sync): We could use null here, but to ease conversion we use "r". 67 // fix this, this is madness :) IsNull()68 inline bool IsNull() const { 69 return IsRoot(); 70 } Clear()71 inline void Clear() { 72 s_ = "r"; 73 } compare(const Id & that)74 inline int compare(const Id& that) const { 75 return s_.compare(that.s_); 76 } 77 inline bool operator == (const Id& that) const { 78 return s_ == that.s_; 79 } 80 inline bool operator != (const Id& that) const { 81 return s_ != that.s_; 82 } 83 inline bool operator < (const Id& that) const { 84 return s_ < that.s_; 85 } 86 inline bool operator > (const Id& that) const { 87 return s_ > that.s_; 88 } 89 value()90 const std::string& value() const { 91 return s_; 92 } 93 94 // Return the next highest ID in the lexicographic ordering. This is 95 // useful for computing upper bounds on std::sets that are ordered 96 // by operator<. 97 Id GetLexicographicSuccessor() const; 98 99 // Dumps the ID as a value and returns it. Transfers ownership of 100 // the StringValue to the caller. 101 base::StringValue* ToValue() const; 102 103 // Three functions are used to work with our proto buffers. 104 std::string GetServerId() const; 105 static Id CreateFromServerId(const std::string& server_id); 106 // This should only be used if you get back a reference to a local 107 // id from the server. Returns a client only opaque id. 108 static Id CreateFromClientString(const std::string& local_id); 109 110 // This method returns an ID that will compare less than any valid ID. 111 // The returned ID is not a valid ID itself. This is useful for 112 // computing lower bounds on std::sets that are ordered by operator<. 113 static Id GetLeastIdForLexicographicComparison(); 114 115 private: 116 friend scoped_ptr<EntryKernel> UnpackEntry(sql::Statement* statement); 117 friend void BindFields(const EntryKernel& entry, 118 sql::Statement* statement); 119 SYNC_EXPORT_PRIVATE friend std::ostream& operator<<(std::ostream& out, 120 const Id& id); 121 friend class MockConnectionManager; 122 friend class SyncableIdTest; 123 124 std::string s_; 125 }; 126 127 SYNC_EXPORT_PRIVATE Id GetNullId(); 128 129 } // namespace syncable 130 } // namespace syncer 131 132 #endif // SYNC_SYNCABLE_SYNCABLE_ID_H_ 133