AccessExample.cpp

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1997-2005
 *      Sleepycat Software.  All rights reserved.
 *
 * $Id: AccessExample.cpp,v 12.1 2005/06/16 20:22:14 bostic Exp $
 */

#include <sys/types.h>

#include <iostream>
#include <iomanip>
#include <errno.h>
#include <stdlib.h>
#include <string.h>

#ifdef _WIN32
extern "C" {
  extern int getopt(int, char * const *, const char *);
  extern int optind;
}
#else
#include <unistd.h>
#endif

#include <db_cxx.h>

#define DATABASE        "access.db"

using std::cin;
using std::cout;
using std::cerr;

class AccessExample
{
public:
        AccessExample();
        void run(bool removeExistingDatabase, const char *fileName);

private:
        // no need for copy and assignment
        AccessExample(const AccessExample &);
        void operator = (const AccessExample &);
};

int
usage()
{
        (void)fprintf(stderr, "usage: AccessExample [-r] [database]\n");
        return (EXIT_FAILURE);
}

int
main(int argc, char *argv[])
{
        int ch, rflag;
        const char *database;

        rflag = 0;
        while ((ch = getopt(argc, argv, "r")) != EOF)
                switch (ch) {
                case 'r':
                        rflag = 1;
                        break;
                case '?':
                default:
                        return (usage());
                }
        argc -= optind;
        argv += optind;

        /* Accept optional database name. */
        database = *argv == NULL ? DATABASE : argv[0];

        // Use a try block just to report any errors.
        // An alternate approach to using exceptions is to
        // use error models (see DbEnv::set_error_model()) so
        // that error codes are returned for all Berkeley DB methods.
        //
        try {
                AccessExample app;
                app.run((bool)(rflag == 1 ? true : false), database);
                return (EXIT_SUCCESS);
        }
        catch (DbException &dbe) {
                cerr << "AccessExample: " << dbe.what() << "\n";
                return (EXIT_FAILURE);
        }
}

AccessExample::AccessExample()
{
}

void AccessExample::run(bool removeExistingDatabase, const char *fileName)
{
        // Remove the previous database.
        if (removeExistingDatabase)
                (void)remove(fileName);

        // Create the database object.
        // There is no environment for this simple example.
        Db db(0, 0);

        db.set_error_stream(&cerr);
        db.set_errpfx("AccessExample");
        db.set_pagesize(1024);          /* Page size: 1K. */
        db.set_cachesize(0, 32 * 1024, 0);
        db.open(NULL, fileName, NULL, DB_BTREE, DB_CREATE, 0664);

        //
        // Insert records into the database, where the key is the user
        // input and the data is the user input in reverse order.
        //
        char buf[1024], rbuf[1024];
        char *p, *t;
        int ret;
        u_int32_t len;

        for (;;) {
                cout << "input> ";
                cout.flush();

                cin.getline(buf, sizeof(buf));
                if (cin.eof())
                        break;

                if ((len = (u_int32_t)strlen(buf)) <= 0)
                        continue;
                for (t = rbuf, p = buf + (len - 1); p >= buf;)
                        *t++ = *p--;
                *t++ = '\0';

                Dbt key(buf, len + 1);
                Dbt data(rbuf, len + 1);

                ret = db.put(0, &key, &data, DB_NOOVERWRITE);
                if (ret == DB_KEYEXIST) {
                        cout << "Key " << buf << " already exists.\n";
                }
        }
        cout << "\n";

        // We put a try block around this section of code
        // to ensure that our database is properly closed
        // in the event of an error.
        //
        try {
                // Acquire a cursor for the table.
                Dbc *dbcp;
                db.cursor(NULL, &dbcp, 0);

                // Walk through the table, printing the key/data pairs.
                Dbt key;
                Dbt data;
                while (dbcp->get(&key, &data, DB_NEXT) == 0) {
                        char *key_string = (char *)key.get_data();
                        char *data_string = (char *)data.get_data();
                        cout << key_string << " : " << data_string << "\n";
                }
                dbcp->close();
        }
        catch (DbException &dbe) {
                cerr << "AccessExample: " << dbe.what() << "\n";
        }

        db.close(0);
}

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