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Iterator.cs
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Iterator.cs
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// leveldb-sharp
//
// Copyright (c) 2013, Mirco Bauer <[email protected]>
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
using System;
using System.Collections;
using System.Collections.Generic;
namespace LevelDB
{
/// <summary>
/// DB Iterator
/// </summary>
/// <remarks>
/// This type is not thread safe.
///
/// If two threads share this object, they must protect access to it using
/// their own locking protocol.
/// </remarks>
public class Iterator : IEnumerator<KeyValuePair<string, string>>
{
/// <summary>
/// Native handle
/// </summary>
public IntPtr Handle { get; private set; }
DB DB { get; set; }
ReadOptions ReadOptions { get; set; }
bool IsFirstMove { get; set; }
public bool IsValid {
get {
return Native.leveldb_iter_valid(Handle);
}
}
public string Key {
get {
return Native.leveldb_iter_key(Handle);
}
}
public string Value {
get {
return Native.leveldb_iter_value(Handle);
}
}
object IEnumerator.Current {
get {
return Current;
}
}
public KeyValuePair<string, string> Current {
get {
return new KeyValuePair<string, string>(Key, Value);
}
}
public Iterator(DB db, ReadOptions readOptions)
{
if (db == null) {
throw new ArgumentNullException("db");
}
DB = db;
// keep reference so it doesn't get GCed
ReadOptions = readOptions;
if (ReadOptions == null) {
ReadOptions = new ReadOptions();
}
Handle = Native.leveldb_create_iterator(db.Handle, ReadOptions.Handle);
IsFirstMove = true;
}
~Iterator()
{
if (DB.Handle != IntPtr.Zero) {
Native.leveldb_iter_destroy(Handle);
}
}
public void SeekToFirst()
{
Native.leveldb_iter_seek_to_first(Handle);
}
public void SeekToLast()
{
Native.leveldb_iter_seek_to_last(Handle);
}
public void Seek(string key)
{
Native.leveldb_iter_seek(Handle, key);
}
public void Previous()
{
Native.leveldb_iter_prev(Handle);
}
public void Next()
{
Native.leveldb_iter_next(Handle);
}
public void Reset()
{
IsFirstMove = true;
SeekToFirst();
}
public bool MoveNext()
{
if (IsFirstMove) {
SeekToFirst();
IsFirstMove = false;
return IsValid;
}
Next();
return IsValid;
}
public void Dispose()
{
// ~Iterator() takes already care
}
}
}