mongodb/bson/bsonmisc.h

// @file bsonmisc.h

/*    Copyright 2009 10gen Inc.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */

#pragma once

namespace mongo {

    int getGtLtOp(const BSONElement& e);

    struct BSONElementCmpWithoutField {
        bool operator()( const BSONElement &l, const BSONElement &r ) const {
            return l.woCompare( r, false ) < 0;
        }
    };
   
    class BSONObjCmp {
    public:
        BSONObjCmp( const BSONObj &_order = BSONObj() ) : order( _order ) {}
        bool operator()( const BSONObj &l, const BSONObj &r ) const {
            return l.woCompare( r, order ) < 0;
        }
    private:
        BSONObj order;
    };

    class BSONObjCmpDefaultOrder : public BSONObjCmp {
    public:
        BSONObjCmpDefaultOrder() : BSONObjCmp( BSONObj() ) {}
    };

    typedef set< BSONObj, BSONObjCmpDefaultOrder > BSONObjSetDefaultOrder;

    enum FieldCompareResult {
        LEFT_SUBFIELD = -2,
        LEFT_BEFORE = -1,
        SAME = 0,
        RIGHT_BEFORE = 1 ,
        RIGHT_SUBFIELD = 2
    };

    FieldCompareResult compareDottedFieldNames( const string& l , const string& r );

/** Use BSON macro to build a BSONObj from a stream 

    e.g., 
       BSON( "name" << "joe" << "age" << 33 )

    with auto-generated object id:
       BSON( GENOID << "name" << "joe" << "age" << 33 )
 
    The labels GT, GTE, LT, LTE, NE can be helpful for stream-oriented construction
    of a BSONObj, particularly when assembling a Query.  For example,
    BSON( "a" << GT << 23.4 << NE << 30 << "b" << 2 ) produces the object
    { a: { \$gt: 23.4, \$ne: 30 }, b: 2 }.
*/
#define BSON(x) (( mongo::BSONObjBuilder(64) << x ).obj())

/** Use BSON_ARRAY macro like BSON macro, but without keys

    BSONArray arr = BSON_ARRAY( "hello" << 1 << BSON( "foo" << BSON_ARRAY( "bar" << "baz" << "qux" ) ) );

 */
#define BSON_ARRAY(x) (( mongo::BSONArrayBuilder() << x ).arr())

    /* Utility class to auto assign object IDs.
       Example:
         cout << BSON( GENOID << "z" << 3 ); // { _id : ..., z : 3 }
    */
    extern struct GENOIDLabeler { } GENOID;

    /* Utility class to add a Date element with the current time
       Example: 
         cout << BSON( "created" << DATENOW ); // { created : "2009-10-09 11:41:42" }
    */
    extern struct DateNowLabeler { } DATENOW;

    // Utility class to implement GT, GTE, etc as described above.
    class Labeler {
    public:
        struct Label {
            Label( const char *l ) : l_( l ) {}
            const char *l_;
        };
        Labeler( const Label &l, BSONObjBuilderValueStream *s ) : l_( l ), s_( s ) {}
        template<class T>
        BSONObjBuilder& operator<<( T value );

        /* the value of the element e is appended i.e. for 
             "age" << GT << someElement
           one gets 
             { age : { $gt : someElement's value } } 
        */
        BSONObjBuilder& operator<<( const BSONElement& e );
    private:
        const Label &l_;
        BSONObjBuilderValueStream *s_;
    };
    
    extern Labeler::Label GT;
    extern Labeler::Label GTE;
    extern Labeler::Label LT;
    extern Labeler::Label LTE;
    extern Labeler::Label NE;
    extern Labeler::Label SIZE;


    // $or helper: OR(BSON("x" << GT << 7), BSON("y" << LT << 6));
    // becomes   : {$or: [{x: {$gt: 7}}, {y: {$lt: 6}}]}
    inline BSONObj OR(const BSONObj& a, const BSONObj& b);
    inline BSONObj OR(const BSONObj& a, const BSONObj& b, const BSONObj& c);
    inline BSONObj OR(const BSONObj& a, const BSONObj& b, const BSONObj& c, const BSONObj& d);
    inline BSONObj OR(const BSONObj& a, const BSONObj& b, const BSONObj& c, const BSONObj& d, const BSONObj& e);
    inline BSONObj OR(const BSONObj& a, const BSONObj& b, const BSONObj& c, const BSONObj& d, const BSONObj& e, const BSONObj& f);
    // definitions in bsonobjbuilder.h b/c of incomplete types
    
    // Utility class to implement BSON( key << val ) as described above.
    class BSONObjBuilderValueStream : public boost::noncopyable {
    public:
        friend class Labeler;
        BSONObjBuilderValueStream( BSONObjBuilder * builder );

        BSONObjBuilder& operator<<( const BSONElement& e );
        
        template<class T> 
        BSONObjBuilder& operator<<( T value );

        BSONObjBuilder& operator<<(DateNowLabeler& id);
        
        Labeler operator<<( const Labeler::Label &l );

        void endField( const char *nextFieldName = 0 );
        bool subobjStarted() const { return _fieldName != 0; }
        
    private:
        const char * _fieldName;
        BSONObjBuilder * _builder;

        bool haveSubobj() const { return _subobj.get() != 0; }
        BSONObjBuilder *subobj();
        auto_ptr< BSONObjBuilder > _subobj;
    };
    
    /**
       used in conjuction with BSONObjBuilder, allows for proper buffer size to prevent crazy memory usage
     */
    class BSONSizeTracker {
    public:
        BSONSizeTracker(){
            _pos = 0;
            for ( int i=0; i<SIZE; i++ )
                _sizes[i] = 512; // this is the default, so just be consistent
        }
        
        ~BSONSizeTracker(){
        }
        
        void got( int size ){
            _sizes[_pos++] = size;
            if ( _pos >= SIZE )
                _pos = 0;
        }
        
        /**
         * right now choosing largest size
         */
        int getSize() const {
            int x = 16; // sane min
            for ( int i=0; i<SIZE; i++ ){
                if ( _sizes[i] > x )
                    x = _sizes[i];
            }
            return x;
        }
        
    private:
        enum { SIZE = 10 };
        int _pos;
        int _sizes[SIZE];
    };

}