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Ran auto-cleanup of interval tree node
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@apacha
apacha committed Apr 29, 2021
1 parent 495ff5e commit f14ea28
Showing 1 changed file with 36 additions and 47 deletions.
83 changes: 36 additions & 47 deletions IntervalTree/IntervalTreeNode.cs
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Original file line number Diff line number Diff line change
@@ -1,38 +1,37 @@
using System.Collections.Generic;
using System.Linq;

namespace IntervalTree
{
/// <summary>
/// A node of the range tree. Given a list of items, it builds
/// its subtree. Also contains methods to query the subtree.
/// Basically, all interval tree logic is here.
/// A node of the range tree. Given a list of items, it builds
/// its subtree. Also contains methods to query the subtree.
/// Basically, all interval tree logic is here.
/// </summary>
internal class IntervalTreeNode<TKey, TValue> : IComparer<RangeValuePair<TKey, TValue>>
{
private readonly TKey center;
private readonly IntervalTreeNode<TKey, TValue> leftNode;
private readonly IntervalTreeNode<TKey, TValue> rightNode;
private readonly RangeValuePair<TKey, TValue>[] items;

private readonly IComparer<TKey> comparer;
private readonly RangeValuePair<TKey, TValue>[] items;
private readonly IntervalTreeNode<TKey, TValue> leftNode;
private readonly IntervalTreeNode<TKey, TValue> rightNode;

/// <summary>
/// Initializes an empty node.
/// Initializes an empty node.
/// </summary>
/// <param name="comparer">The comparer used to compare two items.</param>
public IntervalTreeNode(IComparer<TKey> comparer)
{
this.comparer = comparer ?? Comparer<TKey>.Default;

center = default(TKey);
center = default;
leftNode = null;
rightNode = null;
items = null;
}

/// <summary>
/// Initializes a node with a list of items, builds the sub tree.
/// Initializes a node with a list of items, builds the sub tree.
/// </summary>
/// <param name="items">The items that should be added to this node</param>
/// <param name="comparer">The comparer used to compare two items.</param>
Expand All @@ -47,8 +46,9 @@ public IntervalTreeNode(IList<RangeValuePair<TKey, TValue>> items, IComparer<TKe
endPoints.Add(item.From);
endPoints.Add(item.To);
}

endPoints.Sort(this.comparer);

// the median is used as center value
if (endPoints.Count > 0)
{
Expand All @@ -66,14 +66,12 @@ public IntervalTreeNode(IList<RangeValuePair<TKey, TValue>> items, IComparer<TKe
// if it is on the right of the center, add it to the right items
// otherwise (range overlaps the center), add the item to this node's items
foreach (var o in items)
{
if (this.comparer.Compare(o.To, center) < 0)
left.Add(o);
else if (this.comparer.Compare(o.From, center) > 0)
right.Add(o);
else
inner.Add(o);
}

// sort the items, this way the query is faster later on
if (inner.Count > 0)
Expand All @@ -94,27 +92,42 @@ public IntervalTreeNode(IList<RangeValuePair<TKey, TValue>> items, IComparer<TKe
rightNode = new IntervalTreeNode<TKey, TValue>(right, this.comparer);
}

public TKey Max { get; }

public TKey Min { get; }

/// <summary>
/// Returns less than 0 if this range's From is less than the other, greater than 0 if greater.
/// If both are equal, the comparison of the To values is returned.
/// 0 if both ranges are equal.
/// </summary>
/// <param name="x">The first item.</param>
/// <param name="y">The other item.</param>
/// <returns></returns>
int IComparer<RangeValuePair<TKey, TValue>>.Compare(RangeValuePair<TKey, TValue> x,
RangeValuePair<TKey, TValue> y)
{
var fromComp = comparer.Compare(x.From, y.From);
if (fromComp == 0)
return comparer.Compare(x.To, y.To);
return fromComp;
}

/// <summary>
/// Performs a point query with a single value.
/// All items with overlapping ranges are returned.
/// Performs a point query with a single value.
/// All items with overlapping ranges are returned.
/// </summary>
public IEnumerable<TValue> Query(TKey value)
{
var results = new List<TValue>();

// If the node has items, check for leaves containing the value.
if (items != null)
{
foreach (var o in items)
{
if (comparer.Compare(o.From, value) > 0)
break;
else if (comparer.Compare(value, o.From) >= 0 && comparer.Compare(value, o.To) <= 0)
{
results.Add(o.Value);
}
}
}

// go to the left or go to the right of the tree, depending
// where the query value lies compared to the center
Expand All @@ -128,24 +141,20 @@ public IEnumerable<TValue> Query(TKey value)
}

/// <summary>
/// Performs a range query.
/// All items with overlapping ranges are returned.
/// Performs a range query.
/// All items with overlapping ranges are returned.
/// </summary>
public IEnumerable<TValue> Query(TKey from, TKey to)
{
var results = new List<TValue>();

// If the node has items, check for leaves intersecting the range.
if (items != null)
{
foreach (var o in items)
{
if (comparer.Compare(o.From, to) > 0)
break;
else if (comparer.Compare(to, o.From) >= 0 && comparer.Compare(from, o.To) <= 0)
results.Add(o.Value);
}
}

// go to the left or go to the right of the tree, depending
// where the query value lies compared to the center
Expand All @@ -156,25 +165,5 @@ public IEnumerable<TValue> Query(TKey from, TKey to)

return results;
}

/// <summary>
/// Returns less than 0 if this range's From is less than the other, greater than 0 if greater.
/// If both are equal, the comparison of the To values is returned.
/// 0 if both ranges are equal.
/// </summary>
/// <param name="x">The first item.</param>
/// <param name="y">The other item.</param>
/// <returns></returns>
int IComparer<RangeValuePair<TKey, TValue>>.Compare(RangeValuePair<TKey, TValue> x, RangeValuePair<TKey, TValue> y)
{
var fromComp = comparer.Compare(x.From, y.From);
if (fromComp == 0)
return comparer.Compare(x.To, y.To);
return fromComp;
}

public TKey Max { get; }

public TKey Min { get; }
}
}

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