testkeyrange.cpp

mysql数据库源代码

/*NOTE: AccessExample changed to test Db.key_range.
 * We made a global change of /AccessExample/TestKeyRange/,
 * the only other changes are marked with comments that
 * are notated as 'ADDED'.
 */
/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1997-2002
 *	Sleepycat Software.  All rights reserved.
 *
 * $Id: TestKeyRange.cpp,v 1.4 2002/01/23 14:26:41 bostic Exp $
 */

#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>

#include <iostream.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#ifndef _MSC_VER
#include <unistd.h>
#endif
#endif

#include <iomanip.h>
#include <db_cxx.h>

class TestKeyRange
{
public:
	TestKeyRange();
	void run();

private:
	static const char FileName[];

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

static void usage();          // forward

int main(int argc, char *argv[])
{
	if (argc > 1) {
		usage();
	}

	// 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 {
		TestKeyRange app;
		app.run();
		return 0;
	}
	catch (DbException &dbe) {
		cerr << "TestKeyRange: " << dbe.what() << "\n";
		return 1;
	}
}

static void usage()
{
	cerr << "usage: TestKeyRange\n";
	exit(1);
}

const char TestKeyRange::FileName[] = "access.db";

TestKeyRange::TestKeyRange()
{
}

void TestKeyRange::run()
{
	// Remove the previous database.
	(void)unlink(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("TestKeyRange");
	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];
	char rbuf[1024];
	char *t;
	char *p;
	int ret;
	int len;
	Dbt *firstkey = NULL;
	char firstbuf[1024];

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

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

		if ((len = 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);
		if (firstkey == NULL) {
			strcpy(firstbuf, buf);
			firstkey = new Dbt(firstbuf, 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);

		/*ADDED...*/
		DB_KEY_RANGE range;
		memset(&range, 0, sizeof(range));

		db.key_range(NULL, firstkey, &range, 0);
		printf("less: %f\n", range.less);
		printf("equal: %f\n", range.equal);
		printf("greater: %f\n", range.greater);
		/*end ADDED*/

		Dbt key;
		Dbt data;

		// Walk through the table, printing the key/data pairs.
		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 << "TestKeyRange: " << dbe.what() << "\n";
	}

	db.close(0);
}