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148 lines
3.0 KiB
C++
148 lines
3.0 KiB
C++
//
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// Array.h
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//
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// Library: MongoDB
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// Package: MongoDB
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// Module: ObjectId
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//
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// Definition of the ObjectId class.
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//
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// Copyright (c) 2012, Applied Informatics Software Engineering GmbH.
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// and Contributors.
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//
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// SPDX-License-Identifier: BSL-1.0
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//
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#ifndef MongoDB_ObjectId_INCLUDED
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#define MongoDB_ObjectId_INCLUDED
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#include "Poco/MongoDB/MongoDB.h"
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#include "Poco/MongoDB/Element.h"
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#include "Poco/Timestamp.h"
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namespace Poco {
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namespace MongoDB {
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class MongoDB_API ObjectId
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/// ObjectId is a 12-byte BSON type, constructed using:
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///
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/// - a 4-byte timestamp,
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/// - a 3-byte machine identifier,
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/// - a 2-byte process id, and
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/// - a 3-byte counter, starting with a random value.
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///
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/// In MongoDB, documents stored in a collection require a unique _id field that acts
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/// as a primary key. Because ObjectIds are small, most likely unique, and fast to generate,
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/// MongoDB uses ObjectIds as the default value for the _id field if the _id field is not
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/// specified; i.e., the mongod adds the _id field and generates a unique ObjectId to assign
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/// as its value.
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{
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public:
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using Ptr = SharedPtr<ObjectId>;
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explicit ObjectId(const std::string& id);
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/// Creates an ObjectId from a string.
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///
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/// The string must contain a hexadecimal representation
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/// of an object ID. This means a string of 24 characters.
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ObjectId(const ObjectId& copy);
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/// Creates an ObjectId by copying another one.
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virtual ~ObjectId();
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/// Destroys the ObjectId.
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Timestamp timestamp() const;
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/// Returns the timestamp which is stored in the first four bytes of the id
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std::string toString(const std::string& fmt = "%02x") const;
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/// Returns the id in string format. The fmt parameter
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/// specifies the formatting used for individual members
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/// of the ID char array.
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private:
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ObjectId();
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static int fromHex(char c);
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static char fromHex(const char* c);
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unsigned char _id[12];
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friend class BSONWriter;
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friend class BSONReader;
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friend class Document;
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};
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//
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// inlines
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//
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inline Timestamp ObjectId::timestamp() const
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{
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int time;
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char* T = (char *) &time;
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T[0] = _id[3];
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T[1] = _id[2];
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T[2] = _id[1];
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T[3] = _id[0];
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return Timestamp::fromEpochTime((time_t) time);
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}
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inline int ObjectId::fromHex(char c)
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{
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if ( '0' <= c && c <= '9' )
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return c - '0';
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if ( 'a' <= c && c <= 'f' )
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return c - 'a' + 10;
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if ( 'A' <= c && c <= 'F' )
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return c - 'A' + 10;
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return 0xff;
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}
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inline char ObjectId::fromHex(const char* c)
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{
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return (char)((fromHex(c[0]) << 4 ) | fromHex(c[1]));
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}
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// BSON Embedded Document
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// spec: ObjectId
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template<>
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struct ElementTraits<ObjectId::Ptr>
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{
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enum { TypeId = 0x07 };
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static std::string toString(const ObjectId::Ptr& id,
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int indent = 0,
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const std::string& fmt = "%02x")
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{
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return id->toString(fmt);
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}
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};
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template<>
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inline void BSONReader::read<ObjectId::Ptr>(ObjectId::Ptr& to)
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{
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_reader.readRaw((char*) to->_id, 12);
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}
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template<>
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inline void BSONWriter::write<ObjectId::Ptr>(ObjectId::Ptr& from)
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{
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_writer.writeRaw((char*) from->_id, 12);
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}
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} } // namespace Poco::MongoDB
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#endif // MongoDB_ObjectId_INCLUDED
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