80 lines
2.2 KiB
C#
80 lines
2.2 KiB
C#
namespace SpriteCompiler.AI
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{
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using System;
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using System.Collections.Generic;
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using System.Linq;
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public abstract class AbstractAISearch<A, S, T, C>
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where T : ISearchNode<A, S, T, C>
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where C : IComparable<C>
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{
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// Conceptually the expander is responsible for two things:
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//
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// 1. Creating a node's successors via the Successor Function
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// and wrapping them in SearchNodes (computing path costs
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// and heuristics, as well).
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//
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// 2. Creating a search node from a state. This lets us
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// decouple the search algorithm from the state expansion
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private INodeExpander<A, S, T, C> expander;
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public AbstractAISearch(INodeExpander<A, S, T, C> expander)
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{
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this.expander = expander;
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}
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public INodeExpander<A, S, T, C> Expander { get { return expander; } }
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public IEnumerable<T> Solution(T node)
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{
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var sequence = new List<T>();
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while (node != null)
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{
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sequence.Add(node);
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node = node.Parent;
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}
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sequence.Reverse();
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return sequence;
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}
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public IEnumerable<T> ExtendSearch(ISearchProblem<A, S, C> problem, IQueue<T> fringe)
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{
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while (!fringe.Empty)
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{
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var node = fringe.Remove();
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if (problem.IsGoal(node.State))
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{
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return Solution(node);
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}
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AddNodes(fringe, node, problem);
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}
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return Enumerable.Empty<T>();
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}
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public IEnumerable<T> Expand(ISearchProblem<A, S, C> problem, T node)
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{
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return expander.Expand(problem, node);
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}
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public bool IsFailure(IEnumerable<T> solution)
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{
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return !solution.Any();
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}
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public IEnumerable<T> Search(ISearchProblem<A, S, C> problem, IQueue<T> fringe, S initialState)
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{
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fringe.Enqueue(expander.CreateNode(default(T), initialState));
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return ExtendSearch(problem, fringe);
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}
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protected abstract void AddNodes(IQueue<T> fringe, T node, ISearchProblem<A, S, C> problem);
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}
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}
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