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EagerLoadingEnumerable.cs
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148 lines (129 loc) · 5.88 KB
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namespace Simple.Data.Ado
{
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using Extensions;
using QueryPolyfills;
public class EagerLoadingEnumerable : IEnumerable<IDictionary<string,object>>
{
private readonly IEnumerable<IDictionary<string, object>> _source;
private readonly object _listLock = new object();
private IList<IDictionary<string, object>> _list;
public EagerLoadingEnumerable(IEnumerable<IDictionary<string, object>> source)
{
_source = source;
}
public IEnumerator<IDictionary<string, object>> GetEnumerator()
{
lock (_listLock)
{
if (_list == null)
{
_list = CreateObjectGraphs().ToList();
}
}
return _list.GetEnumerator();
}
IEnumerator IEnumerable.GetEnumerator()
{
return GetEnumerator();
}
private IEnumerable<IDictionary<string,object>> CreateObjectGraphs()
{
var load = BuildLoadDictionary();
IDictionary<string,int> index = null;
foreach (var kvp in load)
{
if (index == null)
{
index = kvp.Key.Keys.Select((k, i) => new KeyValuePair<string, int>(k, i)).ToDictionary(HomogenizedEqualityComparer.DefaultInstance);
}
var row = new OptimizedDictionary<string, object>(index, kvp.Key.Values);
foreach (var sub in kvp.Value)
{
if (sub.Value.Single != null)
{
row[sub.Key] = sub.Value.Single;
}
else if (sub.Value.Collection != null)
{
row[sub.Key] = sub.Value.Collection.ToList();
}
}
yield return row;
}
}
private Dictionary<IDictionary<string, object>, IDictionary<string, WithContainer>> BuildLoadDictionary()
{
var load =
new Dictionary<IDictionary<string, object>, IDictionary<string, WithContainer>>(
new DictionaryEqualityComparer());
foreach (var dict in _source)
{
IDictionary<string, WithContainer> withContainers;
var main = new SubDictionary<string, object>(dict, s => !s.StartsWith("__with"));
if (!load.TryGetValue(main, out withContainers))
{
withContainers = new Dictionary<string, WithContainer>();
load.Add(main, withContainers);
foreach (var tuple in ExtractSingleObjects(dict))
{
var withContainer = new WithContainer();
withContainer.SetSingle(tuple.Item2);
if (!ReferenceEquals(withContainer.Single, null))
{
withContainers.Add(tuple.Item1, withContainer);
}
}
}
foreach (var tuple in ExtractCollectionObjects(dict))
{
if (!withContainers.ContainsKey(tuple.Item1))
{
withContainers.Add(tuple.Item1, new WithContainer());
}
withContainers[tuple.Item1].AddToCollection(tuple.Item2);
}
}
return load;
}
private class WithContainer
{
public HashSet<IDictionary<string, object>> Collection { get; private set; }
public IDictionary<string, object> Single { get; private set; }
public void AddToCollection(IDictionary<string,object> row)
{
if (row.All(kvp => ReferenceEquals(null, kvp.Value))) return;
if (Collection == null) Collection = new HashSet<IDictionary<string, object>>(new DictionaryEqualityComparer());
Collection.Add(row);
}
public void SetSingle(IDictionary<string,object> row)
{
if (row.All(kvp => ReferenceEquals(null, kvp.Value))) return;
Single = row;
}
}
private IEnumerable<Tuple<string,Dictionary<string,object>>> ExtractSingleObjects(IDictionary<string,object> source)
{
var names =
source.Keys.Where(k => k.StartsWith("__with1__")).Select(
k => k.Split(new[] {"__"}, StringSplitOptions.RemoveEmptyEntries)[1]).Distinct().ToList();
return from name in names
let pattern = "__with1__" + name + "__"
select Tuple.Create(name, source.Where(kvp => kvp.Key.StartsWith(pattern))
.ToDictionary(kvp => kvp.Key.Replace(pattern, ""), kvp => kvp.Value, HomogenizedEqualityComparer.DefaultInstance));
}
private IEnumerable<Tuple<string,Dictionary<string,object>>> ExtractCollectionObjects(IDictionary<string,object> source)
{
var names =
source.Keys.Where(k => k.StartsWith("__withn__")).Select(
k => k.Split(new[] {"__"}, StringSplitOptions.RemoveEmptyEntries)[1]).Distinct().ToList();
return from name in names
let pattern = "__withn__" + name + "__"
select Tuple.Create(name, source.Where(kvp => kvp.Key.StartsWith(pattern))
.ToDictionary(kvp => kvp.Key.Replace(pattern, ""), kvp => kvp.Value, HomogenizedEqualityComparer.DefaultInstance));
}
}
}