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Cursor.cs
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Cursor.cs
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using System;
using System.Collections.Generic;
using System.IO;
using MongoDB.Driver.Connections;
using MongoDB.Driver.Protocol;
namespace MongoDB.Driver
{
public class Cursor : ICursor
{
private Connection connection;
private ReplyMessage reply;
#region "Properties"
private long id = -1;
public long Id {
get { return id; }
}
private String fullCollectionName;
public string FullCollectionName {
get { return fullCollectionName; }
}
private bool modifiable = true;
public bool Modifiable {
get { return modifiable; }
}
#endregion
public Cursor (Connection conn, string fullCollectionName){
this.connection = conn;
this.fullCollectionName = fullCollectionName;
}
public Cursor (Connection conn, String fullCollectionName, Document spec, int limit, int skip, Document fields) : this(conn, fullCollectionName){
if (spec == null)
spec = new Document ();
this.spec = spec;
this.limit = limit;
this.skip = skip;
this.fields = fields;
}
#region "Fluency"
private Document spec;
public ICursor Spec (IEnumerable<KeyValuePair<String, Object>> spec){
TryModify ();
this.spec = EnsureIsDocument(spec);
return this;
}
private int limit;
public ICursor Limit (int limit){
TryModify ();
this.limit = limit;
return this;
}
private int skip;
public ICursor Skip (int skip){
TryModify ();
this.skip = skip;
return this;
}
private Document fields;
public ICursor Fields (IEnumerable<KeyValuePair<String, Object>> fields){
TryModify ();
this.fields = EnsureIsDocument(fields);
return this;
}
private QueryOptions options;
public ICursor Options (QueryOptions options){
TryModify ();
this.options = options;
return this;
}
#region "Spec Options"
private Document specOpts = new Document ();
public ICursor Sort (string field){
return this.Sort (field, IndexOrder.Ascending);
}
public ICursor Sort (string field, IndexOrder order){
return this.Sort (new Document ().Append (field, order));
}
public ICursor Sort (IEnumerable<KeyValuePair<String, Object>> fields){
TryModify ();
AddOrRemoveSpecOpt ("$orderby", fields);
return this;
}
public ICursor Hint (IEnumerable<KeyValuePair<String, Object>> index){
TryModify ();
AddOrRemoveSpecOpt ("$hint", index);
return this;
}
public ICursor Snapshot (IEnumerable<KeyValuePair<String, Object>> index){
TryModify ();
AddOrRemoveSpecOpt ("$snapshot", index);
return this;
}
public Document Explain (){
TryModify ();
specOpts["$explain"] = true;
IEnumerable<Document> docs = this.Documents;
using ((IDisposable)docs) {
foreach (Document doc in docs) {
return doc;
}
}
throw new InvalidOperationException ("Explain failed.");
}
#endregion
#endregion
public IEnumerable<Document> Documents {
get {
if (this.reply == null) {
RetrieveData ();
}
int docsReturned = 0;
Document[] docs = this.reply.Documents;
Boolean shouldBreak = false;
while (!shouldBreak) {
foreach (Document doc in docs) {
if ((this.limit == 0) || (this.limit != 0 && docsReturned < this.limit)) {
docsReturned++;
yield return doc;
} else {
shouldBreak = true;
yield break;
}
}
if (this.Id != 0 && shouldBreak == false) {
RetrieveMoreData ();
docs = this.reply.Documents;
if (docs == null) {
shouldBreak = true;
}
} else {
shouldBreak = true;
}
}
}
}
private void RetrieveData (){
QueryMessage query = new QueryMessage ();
query.FullCollectionName = this.FullCollectionName;
query.Query = BuildSpec ();
query.NumberToReturn = this.limit;
query.NumberToSkip = this.skip;
query.Options = options;
if (this.fields != null) {
query.ReturnFieldSelector = (Document)this.fields;
}
try {
this.reply = connection.SendTwoWayMessage (query);
this.id = this.reply.CursorID;
if (this.limit < 0)
this.limit = this.limit * -1;
} catch (IOException ioe) {
throw new MongoCommException ("Could not read data, communication failure", this.connection, ioe);
}
}
private void RetrieveMoreData (){
GetMoreMessage gmm = new GetMoreMessage (this.fullCollectionName, this.Id, this.limit);
try {
this.reply = connection.SendTwoWayMessage (gmm);
this.id = this.reply.CursorID;
} catch (IOException ioe) {
this.id = 0;
throw new MongoCommException ("Could not read data, communication failure", this.connection, ioe);
}
}
public void Dispose (){
if (this.Id == 0)
return;
//All server side resources disposed of.
KillCursorsMessage kcm = new KillCursorsMessage (this.Id);
try {
this.id = 0;
connection.SendMessage (kcm);
} catch (IOException ioe) {
throw new MongoCommException ("Could not read data, communication failure", this.connection, ioe);
}
}
private void TryModify (){
if (this.modifiable)
return;
throw new InvalidOperationException ("Cannot modify a cursor that has already returned documents.");
}
private void AddOrRemoveSpecOpt (string key, IEnumerable<KeyValuePair<String, Object>> doc){
if (doc == null) {
specOpts.Remove (key);
} else {
specOpts[key] = EnsureIsDocument(doc);
}
}
private Document BuildSpec (){
if (this.specOpts.Count == 0)
return this.spec;
Document doc = new Document ();
this.specOpts.CopyTo (doc);
doc["$query"] = this.spec;
return doc;
}
private Document EnsureIsDocument(IEnumerable<KeyValuePair<string,object>> doc){
if(doc is Document) return (Document)doc;
return new Document(doc);
}
}
}