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//
// Threshold.cs
//
// Authors:
// Alexander Chebaturkin (chebaturkin@gmail.com)
//
// Copyright (C) 2012 Alexander Chebaturkin
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System.Collections.Generic;
namespace Mono.CodeContracts.Static.Analysis.Numerical {
public abstract class Threshold<T> {
protected int NextFree;
protected readonly List<T> Values;
protected abstract T MinusInfinity { get; }
protected abstract T PlusInfinity { get; }
protected abstract T Zero { get; }
public int Count { get { return Values.Count; } }
protected Threshold (int size)
{
Values = new List<T> (size) {MinusInfinity, Zero, PlusInfinity};
NextFree = 3;
}
public bool Add (T value)
{
if (NextFree == Values.Count)
return false;
var idx = 0;
while (idx < NextFree && LessThan (Values[idx], value))
idx++;
if (Values[idx].Equals (value))
return false;
Values.Insert (idx, value);
NextFree++;
return true;
}
protected abstract bool LessThan (T a, T b);
public T GetNext (T value)
{
var index = BinarySearch (value, 0, NextFree - 1);
if (index >= 0)
return Values[index];
var nextIndex = ~index; //because binary search returns position of next item if not found
return Values[nextIndex];
}
public T GetPrevious (T value)
{
var index = BinarySearch (value, 0, NextFree - 1);
if (index >= 0)
return Values[index];
var nextIndex = ~index;
return Values[nextIndex - 1];
}
public int BinarySearch (T value, int low, int hi)
{
while (low <= hi) {
var median = low + ((hi - low) >> 1);
if (Values[median].Equals (value))
return median;
if (LessThan (Values[median], value))
low = median + 1;
else
hi = median - 1;
}
return ~low;
}
}
}
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