114 lines
3.6 KiB
C#
114 lines
3.6 KiB
C#
#region Copyright & License Information
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/*
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* Copyright (c) The OpenRA Developers and Contributors
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* This file is part of OpenRA, which is free software. It is made
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* available to you under the terms of the GNU General Public License
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* as published by the Free Software Foundation, either version 3 of
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* the License, or (at your option) any later version. For more
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* information, see COPYING.
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*/
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#endregion
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using System;
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using System.Collections.Generic;
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namespace OpenRA.Mods.Common.Pathfinder
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{
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/// <summary>
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/// Represents a pathfinding graph with nodes and edges.
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/// Nodes are represented as cells, and pathfinding information
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/// in the form of <see cref="CellInfo"/> is attached to each one.
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/// </summary>
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public interface IPathGraph : IDisposable
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{
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/// <summary>
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/// Given a source node, returns connections to all reachable destination nodes with their cost.
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/// </summary>
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/// <remarks>PERF: Returns a <see cref="List{T}"/> rather than an <see cref="IEnumerable{T}"/> as enumerating
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/// this efficiently is important for pathfinding performance. Callers should interact with this as an
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/// <see cref="IEnumerable{T}"/> and not mutate the result.</remarks>
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List<GraphConnection> GetConnections(CPos source);
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/// <summary>
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/// Gets or sets the pathfinding information for a given node.
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/// </summary>
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CellInfo this[CPos node] { get; set; }
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}
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public static class PathGraph
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{
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public const int PathCostForInvalidPath = int.MaxValue;
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public const short MovementCostForUnreachableCell = short.MaxValue;
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}
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/// <summary>
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/// Represents a full edge in a graph, giving the cost to traverse between two nodes.
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/// </summary>
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public readonly struct GraphEdge
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{
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public readonly CPos Source;
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public readonly CPos Destination;
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public readonly int Cost;
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public GraphEdge(CPos source, CPos destination, int cost)
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{
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if (source == destination)
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throw new ArgumentException($"{nameof(source)} and {nameof(destination)} must refer to different cells");
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if (cost < 0)
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throw new ArgumentOutOfRangeException(nameof(cost), $"{nameof(cost)} cannot be negative");
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if (cost == PathGraph.PathCostForInvalidPath)
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throw new ArgumentOutOfRangeException(nameof(cost), $"{nameof(cost)} cannot be used for an unreachable path");
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Source = source;
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Destination = destination;
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Cost = cost;
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}
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public GraphConnection ToConnection()
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{
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return new GraphConnection(Destination, Cost);
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}
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public override string ToString() => $"{Source} -> {Destination} = {Cost}";
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}
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/// <summary>
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/// Represents part of an edge in a graph, giving the cost to traverse to a node.
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/// </summary>
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public readonly struct GraphConnection
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{
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public static readonly CostComparer ConnectionCostComparer = CostComparer.Instance;
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public sealed class CostComparer : IComparer<GraphConnection>
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{
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public static readonly CostComparer Instance = new CostComparer();
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CostComparer() { }
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public int Compare(GraphConnection x, GraphConnection y)
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{
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return x.Cost.CompareTo(y.Cost);
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}
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}
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public readonly CPos Destination;
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public readonly int Cost;
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public GraphConnection(CPos destination, int cost)
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{
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if (cost < 0)
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throw new ArgumentOutOfRangeException(nameof(cost), $"{nameof(cost)} cannot be negative");
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if (cost == PathGraph.PathCostForInvalidPath)
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throw new ArgumentOutOfRangeException(nameof(cost), $"{nameof(cost)} cannot be used for an unreachable path");
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Destination = destination;
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Cost = cost;
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}
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public GraphEdge ToEdge(CPos source)
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{
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return new GraphEdge(source, Destination, Cost);
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}
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public override string ToString() => $"-> {Destination} = {Cost}";
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}
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}
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