I have two type of nodes, one is MyLinkNode it's used as base, another one is GraphNode which inheritance MyLinkNode.
I try to create MyQueue with MyLinkNode. Everything is OK until I try to add GraphNode to MyQueue. I can't use MyQueue with GraphNode since it's bigger.
An alternative way is create another queue for GraphNode, but that means I would need to create lots of class if I have more type of nodes.
Is there any suggestion?
public class MyQueue<T> where T : MyLinkNode<T>
{
private T Head;
private T Last;
public MyQueue(){ ... }
public void Enqueue(T item)
{
item.Prev = Last;
Last.Next = item;
Last = item;
}
}
public class MyGraphQueue
{
//everything is the same with MyQueue besides the Node Type
//I don't want to create like this.
private GraphNode Head;
private GraphNode Last;
public MyGraphQueue(){ ... }
public void Enqueue(GraphNode item)
{
item.Prev = Last;
Last.Next = item;
Last = item;
}
}
public class MyLinkNode<T>
{
public T data { get; set; }
public MyLinkNode<T> Next { get; set; }
public MyLinkNode<T> Prev { get; set; }
}
public class GraphNode<T> : MyLinkNode<T>
{
public GraphNode()
{
this.adjacencyNodes = new List<GraphNode<T>>();
this.isVisited = false;
}
public List<GraphNode<T>> adjacencyNodes;
public bool isVisited { get; set; }
}
public void BFS<T>(GraphNode<T> v)
{
MyQueue<GraphNode<T>> queue = new MyQueue<GraphNode<T>>(); // error, can't implicit convert GraphNode to MyLinkNode<T>
MyGraphQueue queue = new MyGraphQueue(); //It's how I do now.
}
This is a standard Generics inheritance problem. You need to separate what the Queue needs from the generic type. Just add another base class for the queue constraint.
This will keep the queue to have the guarantee of all items having type T and not require extra types or multiple class definitions for all of the concrete types. Eric Lippert has a good article here on why this limitation was required in the generics system.
public class CallingClass
{
public void BFS(GraphNode v)
{
MyQueue<GraphNode> queue = new MyQueue<GraphNode>(); // error, can't implicit convert GraphNode to MyLinkNode<T>
// MyGraphQueue queue = new MyGraphQueue(); //It's how I do now.
}
}
public class QueueItem
{
public QueueItem Next { get; set; }
public QueueItem Prev { get; set; }
}
public class MyQueue<T> where T : QueueItem
{
private T Head;
private T Last;
public MyQueue() { }
public void Enqueue(T item)
{
item.Prev = Last;
Last.Next = item;
Last = item;
}
}
public class MyLinkNode<T>: QueueItem
{
public T data { get; set; }
}
public class GraphNode : MyLinkNode<string>
{
public GraphNode()
{
this.adjacencyNodes = new List<GraphNode>();
this.isVisited = false;
}
public List<GraphNode> adjacencyNodes;
public bool isVisited { get; set; }
}
MyQueue<T> where T : MyLinkNode<T> cannot accept a MyLinkNode<string>
Beacuse here T is string. but, obviously string doesn't inherit from MyLinkNode
I think the solution is simpler than you imagine.
Just set the type (T) of the value in the queue, and inside use MyLinkNode<T>:
public class MyQueue<T>
{
private MyLinkNode<T> Head;
private MyLinkNode<T> Last;
public void Enqueue(MyLinkNode<T> item)
{
item.Prev = Last;
Last.Next = item;
Last = item;
}
}
public void BFS(GraphNode v)
{
MyQueue<string> queue = new MyQueue<string>(); // no error anymore
queue.Enqueue(v);
}
That's not surprising. You need
public class MyQueue<T, S> where T : MyLinkNode<S>
{
private T Head;
private T Last;
public MyQueue() { }
public void Enqueue(T item)
{
item.Prev = Last;
Last.Next = item;
Last = item;
}
}
public void BFS(GraphNode v)
{
MyQueue<GraphNode, string> queue = new MyQueue<GraphNode, string>();
}
The problem is coming from your first line.
Use:
public class MyQueue<T> where T : MyLinkNode<string> { }
Instead of:
public class MyQueue<T> where T : MyLinkNode<T> { }
and it will work fine.
Related
I will plot an example to illustrate my behind the scene issues.
Let say I have this base generic class :
public abstract class ContainerBase<T>
{
Guid Id {get; init;}
IList<T> Items {get; set;}
bool IsLeaf {get; set;} = false;
/// omitted constructors and so
}
Then I have a whole bunch (undefined number) of concrete Container class that have another ContainerBase<...> as the T type argument :
public class RootContainer : ContainerBase<ChildContainer1>
{...}
public class ChildContainer1: ContainerBase<ChildContainer2>
{...}
public class ChildContainer2: ContainerBase<ChildContainer3>
{...}
...
public class ChildContainerNminus1: ContainerBase<ChildContainerN>
{...}
public class ChildContainerN: ContainerBase<int> // the recursion end here.
{
...
IsLeaf = true;
}
Now let say I have an AddContainer method from an Utility class and have access to the RootContainer object (a singleton for example) that is fully populated of recursive sub containers.
public static class ContainerUtility
{
// What is the Type of the recursive currentContainer ?
public static ContainerBase<T> FindContainer<T>(Guid id, ContainerBase<?> currentContainer)
{
if(currentContainer.Id == id)
return currentContainer;
if(currentContainer.IsLeaf) return default;
foreach(var item in currentContainer.Items)
{
var potential = FindContainer(id, item);
if(potential != default) return potential;
}
return default;
}
public static bool AddContainer<T>(ContainerBase<T> container, Guid parentId)
{
// potential should be of container's parent type (ContainerBase<"T-1">)
// but how to "bybass" an expected type parameter as I cannot know it ?
var potential = FindContainer<?>(parentId, RootContainer.Instance)
if(potential != default && potential is ContainerBase<?>)
{
potential.Items.Add(container)
return true;
}
return false;
}
}
You see, my issue is that I have a base type ContainerBase that is convenient for recursive search as all subClasses allow access to Items list to pursue recursion.
But at each step of the recursion it is a different actual type of ContainerBase<?>.
So I cannot perform cast on the method argument.
maybe use a top level interface that expose a List<object> Items ? Not sure that will end up good.
Bellow was my intermediate mid-solution on my issue.
I'll keep it for the record or erase it if you request it to clarify this response.
Ok I get something more interesting now. I would like to have your criticism of this solution I end up with :
Mainly I abstracted a way higher with a non generic interface to avoid my issue described in OP.
The Interface
public interface IContainer
{
int TAG { get; init; } // usefull for logging purpose
string Name { get; }
Guid Id { get; init; }
public bool IsLeaf { get;}
IList<IContainer>? GetContainers();
void SetContainers(List<IContainer> value);
}
The base class
public abstract class ContainerBase<T> : IContainer where T : IContainer
{
public int TAG { get; init; }
public Guid Id { get; init; }
private IList<IContainer>? _containers = new List<IContainer>();
public IList<T> Items { get; set; } = new List<T>();
public bool IsLeaf => this.GetType() == typeof(T);
public string Name => this.GetType().Name + "_" + TAG;
public ContainerBase(Guid id)
{
TAG = ContainerUtils.ContainerCount++;
Id=id;
}
public ContainerBase()
{
TAG = ContainerUtils.ContainerCount++;
Id = Guid.NewGuid();
}
public IList<IContainer>? GetContainers()
{
if(Items == null) return null;
if(_containers == null || !_containers.Any())
_containers = Items.Where(x => x!=null).Select(x => (IContainer)x!).ToList();
return _containers;
}
public void SetContainers(List<IContainer> value)
{
Items = new List<T>();
foreach(var item in value)
{
if (item is T)
Items.Add((T)item);
}
}
}
The concrete classes
internal class RootContainer : ContainerBase<Child1Container>
{
public RootContainer(Guid id) : base(id)
{
}
public RootContainer() : base()
{
}
}
The intermediate containers are the same only class name change (X = 1 to 3 in my test case)
internal class ChildXContainer : ContainerBase<ChildX+1Container>
{
public ChildXContainer(Guid id) : base(id)
{
}
public ChildXContainer() : base()
{
}
}
The leaf class (end point of my chained containers classes recursion).
internal class LeafContainer : ContainerBase<LeafContainer>
{
public int IntItem { get; set; }
public LeafContainer() : base()
{
}
public LeafContainer(Guid id) : base(id)
{
}
}
Do note I'm using a trick to detect if a ContainerBase<T> concrete implementation is a leaf or not :
If such classes are leaves then they have to derive from ContainerBase<> of themselves.
Kind like the CRTP syntax, but without its meaning.
So I'm not fully satisfied of this trick, but better than my previous attempt so far.
The Utility class
internal static class ContainerUtils
{
public static int ContainerCount = 0;
public static Guid IdToSearch {
get
{
if(!AllIds.Any())
return Guid.Empty;
return AllIds[new Random().Next(AllIds.Count - 1)];
}
//set { IdToSearch = value; }
}
public static List<Guid> AllIds { get; set; } = new();
private static RootContainer _root = BuildContainers();
public static RootContainer Root => _root;
private static RootContainer BuildContainers()
{
LeafContainer Leaf = new LeafContainer();
Child3Container Child3 = new Child3Container();
Child2Container Child2 = new Child2Container();
Child1Container Child1 = new Child1Container();
RootContainer Root = new RootContainer();
Root.Items.Add(Child1);
Child1.Items.Add(Child2);
Child2.Items.Add(Child3);
Child3.Items.Add(Leaf);
Leaf.IntItem = 12;
AllIds.Add(Root.Id);
AllIds.Add(Child1.Id);
AllIds.Add(Child2.Id);
AllIds.Add(Child3.Id);
AllIds.Add(Leaf.Id);
return Root;
}
private static IContainer? _GetSubContainer(this IContainer container, int index)
=> (container == null ||
container.GetContainers() == null ||
index >= container.GetContainers()!.Count) ? null : container.GetContainers()![index];
public static string ContainersToString()
=> ContainersToString(Root);
public static string ContainersToString(IContainer? fromContainer)
{
if (fromContainer == null) return string.Empty;
int i = 0;
string tab = " ";
string res = "";
while(fromContainer != null)
{
res += tab.Repeat(i) + "+" + fromContainer.Name??"NULL";
res += "\n";
i++;
fromContainer = _GetSubContainer(fromContainer, 0);
}
return res;
}
public static IContainer? SearchContainer(Guid id)
=> SearchContainer(id, Root);
public static IContainer? SearchContainer(Guid id, IContainer? fromContainer)
{
if (fromContainer == null) return null;
if (fromContainer.Id == id)
return fromContainer;
if (fromContainer.IsLeaf)
return null;
return SearchContainer(id, fromContainer._GetSubContainer(0));
}
public static bool SetItemToContainer(Guid id, IContainer newContainer)
{
var container = SearchContainer(id);
if(container == null) return false;
if (container._GetSubContainer(0) == null || (container.GetContainers()![0].GetType() != newContainer.GetType()))
return false;
container.GetContainers()![0] = newContainer;
return true;
}
}
The Program and its output
Console.WriteLine(ContainerUtils.ContainersToString());
IContainer newChild2 = new Child2Container();
Console.WriteLine("Child2's Name : " + ContainerUtils.SearchContainer(ContainerUtils.AllIds[2])?.Name ?? "NULL");
Console.WriteLine("New Child2's Name : " + newChild2.Name);
ContainerUtils.SetItemToContainer(ContainerUtils.AllIds[1], newChild2);
Console.WriteLine(ContainerUtils.ContainersToString());
Output
+RootContainer_4
+Child1Container_3
+Child2Container_2
+Child3Container_1
+LeafContainer_0
Child2's Name : Child2Container_2
New Child2's Name : Child2Container_5
+RootContainer_4
+Child1Container_3
+Child2Container_5
OLD answer
I created a new test project with a simpler version of my OP one.
Here is what I ended, and yep found using an interface as a "workish" solution (I'm not completely satisfied).
Let me know what you think of it please.
The interface without generic parameter :
public interface IContainer
{
string Name => this.GetType().Name;
public Guid Id { get; init; }
public IContainer? Item { get; set; }
public bool IsLeaf => Id == Guid.Empty;
}
The base abstract class with the generic parameter :
public abstract class ContainerBase<T> : IContainer where T : IContainer
{
public Guid Id { get; init; }
public T? Item { get; set; }
IContainer? IContainer.Item { get => Item; set => Item = (T)value; }
public ContainerBase(Guid id)
{
Id=id;
}
public ContainerBase()
{
Id = Guid.NewGuid();
}
}
The starting concrete Container class
internal class RootContainer : ContainerBase<Child1Container>
{
public RootContainer(Guid id) : base(id)
{
}
public RootContainer() : base()
{
}
}
The child Container concrete classes.
In my project there is Child1Container, Child2Container and Child3Container. I only display Child1Container here. The other are the same except class name.
internal class Child1Container : ContainerBase<Child2Container>
{
public Child1Container(Guid id) : base(id)
{
}
public Child1Container() : base()
{
}
}
The endind Container (noted Leaf here) :
This is where I found the code most ugly..
internal class LeafContainer : IContainer
{
public int IntItem { get; set; }
public Guid Id { get; init ; }
/// Meh, would be nice to avoid this.
public IContainer? Item { get => null; set => Item = null; }
public LeafContainer()
{
Id = Guid.Empty;
}
}
My utility class :
internal static class ContainerUtils
{
public static Guid IdToSearch { get; set; }
private static RootContainer _root = BuildContainers();
public static RootContainer Root => _root;
private static RootContainer BuildContainers()
{
LeafContainer Leaf = new LeafContainer();
Child3Container Child3 = new Child3Container();
Child2Container Child2 = new Child2Container();
Child1Container Child1 = new Child1Container();
RootContainer Root = new RootContainer();
Root.Item = Child1;
Child1.Item = Child2;
Child2.Item = Child3;
Child3.Item = Leaf;
Leaf.IntItem = 12;
IdToSearch = Root.Id;
return Root;
}
public static IContainer? SearchContainer(Guid id)
=> SearchContainer(id, Root);
public static IContainer? SearchContainer(Guid id, IContainer? fromContainer)
{
if (fromContainer == null) return null;
if(fromContainer.Id == id)
return fromContainer;
if(fromContainer.IsLeaf)
return null;
return SearchContainer(id, fromContainer.Item);
}
}
Finally my Program :
using TestRecursiveGenerics;
var res = ContainerUtils.SearchContainer(ContainerUtils.IdToSearch);
Console.WriteLine("Searching IContainer's Id, and we found : "+ res?.Name ?? "NULL");
I have a IHasTag interface, a TaggableItem class that implements IHasTag and a TaggingManager class which I want to make it the only one responsible for setting or clearing the Tags but I've been struggling all day trying to implement but with no luck.
How can I make this possible?
public class TaggableItem : TaggingManager.IHasTag
{
public string Tag { get; } // read only
}
public class TaggingManager
{
public interface IHasTag
{
string Tag { get; }
}
private List<IHasTag> _taggedItems = new();
public void TagItem(IHasTag item, string tag)
{
item.Tag = tag; // not working
_taggedItems.Add(item);
}
public void ClearAllTags()
{
foreach (var item in _taggedItems)
{
item.Tag = "": // not working
}
_taggedItems.Clear();
}
}
EDIT
I followed Thomas' suggestion and this is what I end up doing. I know it's not perfect, though. Thank you all for your advices.
public interface ITaggable
{
string? Tag { get; }
}
public interface ISelectable
{
bool IsSelected { get; }
}
public interface IItem : ITaggable, ISelectable
{
}
public class Item : IItem
{
protected Item() { }
public bool IsSelected { get; set; }
public string Tag { get; set; } = string.Empty;
// 'Item' will be created here returning IItem.
// So, unless you 'cast' it, you can't set 'Tag' or 'IsSelected'.
public static IItem CreateItem() => new Item();
}
public class SelectionManager
{
protected List<object> _items = new();
public void Select(ISelectable item)
{
if (item is Item selectable)
{
selectable.IsSelected = true;
_items.Add(item);
}
}
public void Unselect(ISelectable item)
{
if (item is Item selectable)
{
selectable.IsSelected = false;
_items.Remove(item);
}
}
}
public class TaggingManager
{
private List<object> _items = new();
public void Tag(ITaggable item, string tag)
{
if (item is Item taggable)
{
taggable.Tag = tag;
_items.Add(item);
}
}
public void Untag(ITaggable item)
{
if (item is Item taggable)
{
taggable.Tag = string.Empty;
_items.Remove(item);
}
}
}
My suggestion would be to have two interfaces for two purposes: reading and writing.
public interface IHasTag // interface for reading. Maybe IReadTag
{
string Tag { get; }
}
public interface ITagChange // interface for writing. Maybe IWriteTag
{
string Tag { set; }
}
public class TaggableItem : IHasTag, ITagChange // implement both
{
public string Tag { get; set; }
}
// Tagging manager gets write access (ITagChange)
public class TaggingManager
{
private List<ITagChange> _taggedItems = new ();
public void TagItem(ITagChange item, string tag)
{
item.Tag = tag;
_taggedItems.Add(item);
}
public void ClearAllTags()
{
foreach (var item in _taggedItems)
{
item.Tag = "";
}
_taggedItems.Clear();
}
}
// Everyone else has read access only (IHasTag)
class SomeoneElse
{
private List<IHasTag> _taggedItems = new ();
public void DoSomething(IHasTag item)
{
_taggedItems.Add(item);
var tag = item.Tag; // do something with the tag
}
}
class Instantiation
{
public void Main()
{
TaggableItem x = new TaggableItem();
TaggingManager m = new TaggingManager();
m.TagItem(x, "name");
SomeoneElse s = new SomeoneElse();
s.DoSomething(x);
}
}
One possible option is to move the "getter" also to the TagManager. Then the manager is responsible for the tags. The object itself does not even need to know about the tags.
You still can restrict this by exchanging object with an interface.
public class TagManager
{
private Dictionary<object, string> _tagedItems = new Dictionary<object, string>();
public bool HasTag(object item)
{
return _tagedItems.ContainsKey(item);
}
public string GetTag(object item)
{
return _tagedItems[item];
}
public void SetTag(object item, string tag)
{
if(!HasTag(item))
{
_tagedItems.Add(item, tag);
}
else
{
_tagedItems[item] = tag;
}
}
}
I don't think that this is really a answer to the OP, but one possible solution for the underlying problem.
I have 3 interfaces.
public interface IItem
{
string Name { get; set; }
}
public interface IEquipable : IItem
{
void Equip();
}
public interface IConsumable : IItem
{
void Use();
}
IEquipable is implemented by the classes Helmet and Bow, and IConsumable is implemented by classes Potion and Food.
Then, I have a class with a property which contains a List of IItem, and proceed to add a few items of both IEquipable and IConsumable after instantiating it.
public class Character
{
public List<IItem> Items { get; private set; }
public Character()
{
this.Items = new List<IItem>();
}
public void AddItem(IItem item)
{
this.Items.Add(item);
}
}
Program.cs
...
Character char = new Character();
char.AddItem(new Potion());
char.AddItem(new Food());
char.AddItem(new Helmet());
char.AddItem(new Bow());
...
Is there a way I can get a List of all IEquipable members from the List of IItems, each AS IEquipable?
I want to do something like
...
List<IEquipable> equipmentList = //do something to char.Items and get all items of type IEquipable.
IEquipment equipment = equipmentList.First(...)
equipment.Equip();
...
I've tried using List<IEquipable> equipmentList = char.Items.OfType<IEquipable>().ToList() but the resulting list ends up empty.
I implemented (and fixed minor typos in) your code like this:
void Main()
{
Character character = new Character();
character.AddItem(new Potion());
character.AddItem(new Food());
character.AddItem(new Helmet());
character.AddItem(new Bow());
List<IEquipable> equipmentList = character.Items.OfType<IEquipable>().ToList();
}
public class Potion : IConsumable
{
public string Name { get; set; }
public void Use()
{
throw new NotImplementedException();
}
}
public class Food : IConsumable
{
public string Name { get; set; }
public void Use()
{
throw new NotImplementedException();
}
}
public class Helmet : IEquipable
{
public string Name { get; set; }
public void Equip()
{
throw new NotImplementedException();
}
}
public class Bow : IEquipable
{
public string Name { get; set; }
public void Equip()
{
throw new NotImplementedException();
}
}
public interface IItem
{
string Name { get; set; }
}
public interface IEquipable : IItem
{
void Equip();
}
public interface IConsumable : IItem
{
void Use();
}
public class Character
{
public List<IItem> Items { get; private set; }
public Character()
{
this.Items = new List<IItem>();
}
public void AddItem(IItem item)
{
this.Items.Add(item);
}
}
Your exact code (albeit char renamed to character) works perfectly fine. The equipmentList ends up with two elements. The issue you're seeing, i.e. "the resulting list ends up empty", is not reproducible with the code you've posted.
You can use the OfType method
Filters the elements of an IEnumerable based on a specified type.
Signature
public static IEnumerable<TResult> OfType<TResult> (this IEnumerable source)
Usage
var equipable = Character.Items.OfType<IEquipable>();
Or encapsulate it as a method in the instance or an extension method if you like
So it does work like I wanted. My actual code just had another issue and I'm a dummy for not actually posting that. So here it is, for future reference.
using System.Collections.Generic;
using RolePlayGame.Library.Items.Backstage;
using System.Linq;
using System.Text;
using System;
namespace RolePlayGame.Library.Characters.Backstage
{
public class Inventory
{
public List<IItem> StoredItems { get; private set; }
public List<EquippedItem> Gear { get; private set; }
public Inventory()
{
this.StoredItems = new List<IItem>();
this.Gear = new List<EquippedItem>();
}
public bool HasItem(string name)
{
return this.StoredItems.Exists(item => item.Name == name);
}
public bool HasItem(IItem item)
{
return this.StoredItems.Contains(item);
}
public void RemoveItem(string name)
{
int firstIndex = this.StoredItems.FindIndex(item => item.Name == name);
if (firstIndex != -1)
{
this.StoredItems.RemoveAt(firstIndex);
}
}
public void RemoveItem(IItem item)
{
int firstIndex = this.StoredItems.IndexOf(item);
if (firstIndex != -1)
{
this.StoredItems.RemoveAt(firstIndex);
}
}
public void AddItem(IItem item, int quantity)
{
for (int i = 0; i < quantity; i++)
{
this.StoredItems.Add(item);
}
}
public void AddItem(IItem item)
{
this.StoredItems.Add(item);
}
public bool CheckEquipmentSlot(EquipmentSlot slot)
{
return this.Gear.Exists(item => item.UsedSlots.Contains(slot));
}
public bool HasEquipment(IEquipment equipment)
{
return this.Gear.Exists(item => item.Item == equipment);
}
public void AddEquipment(IEquipment equipment)
{
IEquipment alreadyEquipped;
foreach (EquipmentSlot slot in equipment.SlotsUsed)
{
if (this.Gear.Exists(item => item.UsedSlots.Contains(slot)))
{
alreadyEquipped = this.Gear.Find(item => item.UsedSlots.Contains(slot)).Item;
this.RemoveEquipment(slot);
this.StoredItems.Add(alreadyEquipped);
}
}
EquippedItem newEquipment = new EquippedItem(equipment);
this.Gear.Add(newEquipment);
}
public void RemoveEquipment(EquipmentSlot slot)
{
this.Gear.RemoveAll(equipment => equipment.UsedSlots.Contains(slot));
}
public int GetAttributeBonusTotal(AttributeType attribute)
{
int bonusTotal = 0;
foreach (IEquipment item in this.StoredItems.OfType<IEquipment>().ToList())
{
bonusTotal += item.GetAttributeBonus(attribute);
}
return bonusTotal;
}
public int GetCarryWeight()
{
int totalWeight = 0;
foreach (IItem item in StoredItems)
{
totalWeight += item.Weight;
}
return totalWeight;
}
public string GearToString()
{
StringBuilder builder = new StringBuilder();
builder.Append(" Equipped Gear:");
foreach (EquippedItem equipment in this.Gear)
{
builder.Append($"\n {equipment.Item.Name}");
}
return builder.ToString();
}
public string ItemsToString()
{
StringBuilder builder = new StringBuilder();
builder.Append(" Inventory:");
foreach (IItem item in this.StoredItems.Distinct())
{
builder.Append($"\n {item.Name} x {this.StoredItems.FindAll(value => value == item).Count()}");
}
return builder.ToString();
}
public int GetDefenseRateAgainstTypeTotal(DamageType againstType)
{
int rate = 0;
List<IOutfit> outfits = this.Gear.Select(value => value.Item).OfType<IOutfit>().ToList();
foreach (IOutfit item in outfits)
{
rate += item.GetDefenseRateAgainstType(againstType);
}
return rate;
}
}
}
One of the last lines has the problem (now fixed). List<IOutfit> outfits = this.Gear.Select(value => value.Item).OfType<IOutfit>().ToList(); used to be List<IOutfit> outfits = this.Gear.OfType<IOutfit>().ToList();. But Gear is of type List<EquippedItem>, and EquippedItem is not an implementation of IItem.
Here is EquippedItem.cs
using RolePlayGame.Library.Items.Backstage;
using System.Collections.Generic;
namespace RolePlayGame.Library
{
public class EquippedItem
{
public List<EquipmentSlot> UsedSlots { get; set; }
public IEquipment Item { get; set; }
public EquippedItem(IEquipment equipment)
{
this.Item = equipment;
this.UsedSlots = equipment.SlotsUsed;
}
}
}
I needed to select the Item property from the items inside Gear as another list before doing the type filtering with .OfType<IOutfit>(). That's where .Select(value => value.Item) enters the stage.
So that's that. I'll learn to post actual code for future questions.
I would like to create a parse tree (not an AST) with ANTLR in target language C#. This seems less then trivial, maybe I'm looking in all the wrong places.
So far, I tried to implement the partials in the generated parser as follows:
public partial class TestParser
{
ParseTree pt = new ParseTree("root", null);
partial void EnterRule(string ruleName, int ruleIndex)
{
ParseTree child = new ParseTree(ruleName, pt);
pt.Children.Add(child);
this.pt = child;
}
partial void LeaveRule(string ruleName, int ruleIndex)
{
this.pt = pt.Parent;
}
}
with ParseTree being
public class ParseTree
{
private List<ParseTree> children = new List<ParseTree>();
public ParseTree(string name, ParseTree parent)
{
this.Parent = parent;
this.Rule = name;
}
public ParseTree Parent { get; private set; }
public string Rule { get; private set; }
public List<ParseTree> Children { get { return children; } }
public Boolean IsTerminal
{
get
{
return (children.Count == 0);
}
}
}
This works, but doesn't fulfill my goal: I can't get the matched tokens/text from this tree. Apart from that, it has an additional drawback: If I want to do this for multiple grammars, I have to copy-paste the partial class everywhere, since it's a partial of the TestParser, nothing higher up the foodchain.
I have looked at http://www.antlr.org/wiki/pages/viewpage.action?pageId=1760 but the generated Parser doesn't have a constructor that takes a ParseTreeBuilder.
Where to now?
I've found a more or less reasonable solution to my problem. It has a major drawback: It only handles the text of production rules that consist only of tokens. This is sufficient for me, but might not be for you. A proper implementation should have token nodes too, so it can be properly walked.
Adaptor:
public class ParseAdaptor : CommonTreeAdaptor
{
private C<ParseTree> container;
public ParseAdaptor(C<ParseTree> container)
: base()
{
this.container = container;
}
public override void AddChild(object t, object child)
{
base.AddChild(t, child);
this.container.Value.Text += base.GetTree(child).Text;
}
}
The ParseTree implementation:
public class ParseTree
{
private string ownText;
private List<ParseTree> children = new List<ParseTree>();
public ParseTree(string name, ParseTree parent)
{
this.Parent = parent;
this.Rule = name;
}
public String Text
{
get
{
if (this.IsTerminal) return this.ownText;
else
{
StringBuilder builder = new StringBuilder();
foreach (ParseTree child in children)
{
builder.Append(child.Text);
}
return builder.ToString();
}
}
set
{
this.ownText = value;
}
}
public ParseTree Parent { get; private set; }
public string Rule { get; private set; }
public List<ParseTree> Children { get { return children; } }
public Boolean IsTerminal
{
get
{
return (children.Count == 0);
}
}
}
//Isn't this the silliest little thing you've ever seen?
//Where is a pointer when you need one?
public class C<T>
{
public T Value { get; set; }
}
and it gets glued together with the partials:
public partial class TestParser
{
C<ParseTree> parseTreeContainer = new C<ParseTree>() { Value = new ParseTree("root", null) };
public ParseTree Tree
{
get
{
return parseTreeContainer.Value;
}
set
{
parseTreeContainer.Value = value;
}
}
partial void CreateTreeAdaptor(ref ITreeAdaptor adaptor)
{
adaptor = new ParseAdaptor(this.parseTreeContainer);
}
partial void EnterRule(string ruleName, int ruleIndex)
{
ParseTree child = new ParseTree(ruleName, Tree);
ParseTree parent = Tree;
parent.Children.Add(child);
Tree = child;
}
partial void LeaveRule(string ruleName, int ruleIndex)
{
Tree = Tree.Parent;
}
}
I have this :
public class CChainElement
{
public CChainElement m_Prev, m_Next;
}
public class CChainList : IEnumerable
{
public CChainElement m_First;
internal void Add(CChainElement Element)
{
if (m_First != null)
m_First.m_Prev = Element;
Element.m_Next = m_First;
m_First = Element;
}
}
public class CEntity : CChainElement
{
}
public class CItem : CEntity
{
}
public class CTest
{
void Test()
{
CChainList AllItem = new CChainList();
CItem Item = new CItem();
AllItem.Add(Item);
CItem FirstItem = AllItem.m_First as CItem;
CItem SecondItem = FirstItem.m_Next as CItem;
}
}
And I'd like to switch to something like this :
public class CChainElement<T> where T : CChainElement<T>
{
public T m_Prev, m_Next;
}
public class CChainList<T> : IEnumerable where T : CChainElement<T>
{
public T m_First;
internal void Add(T Element)
{
if (m_First != null)
m_First.m_Prev = Element;
Element.m_Next = m_First;
m_First = Element;
}
}
public class CEntity : CChainElement<CEntity>
{
}
public class CItem : CEntity
{
}
public class CTest
{
void Test()
{
CChainList<CItem> AllItem = new CChainList<CItem>();
CItem Item = new CItem();
AllItem.Add(Item);
CItem FirstItem = AllItem.m_First; // Yeepee, no more "as CItem" ..! ;-)
CItem SecondItem = FirstItem.m_Next;
}
}
And I get the error that CItem can't be converted to CChainElement<CItem> .
So my question is : is there anyway to constrain public class CChainElement<T> so it'll take CItem graciously, even if it doesn't inherit directly from CChainElement ?
My goal is obviously that all classes inherited from CChainElement<T> being able to be listed with my generic list class, while avoiding the explicit cast.
Thanks in advance for any help !
EDIT: in my full project, CEntity is used for many different things as an abstraction class (ie: I can manipulate Monsters in a similar way than Items through it), so it can't be changed to be a generic CEntity<T> .
CChainElement should not be generic. The only thing that should turn to a generic is CChainList.
public class CChainElement
{
public CChainElement m_Prev, m_Next;
}
public class CChainList<T> : IEnumerable
where T : CChainElement
{
public T m_First;
internal void Add(T Element)
{
if (m_First != null)
m_First.m_Prev = Element;
Element.m_Next = m_First;
m_First = Element;
}
}
public class CEntity : CChainElement
{
}
public class CItem : CEntity
{
}
public class CTest
{
void Test()
{
CChainList<CItem> AllItem = new CChainList<CItem>();
CItem Item = new CItem();
AllItem.Add(Item);
CItem FirstItem = AllItem.m_First;
CItem SecondItem = FirstItem.m_Next;
}
}
Well, this is a fun little problem. You need to make these changes:
public class CEntity<T> : CChainElement<T> where T : CChainElement<T> { ... }
public class CItem : CEntity<CItem> { ... }
Then this will work the way you want:
var allItems = new CChainList<CItem> { new CItem(), new CItem() };
// Both of these are now of type Item.
var firstItem = allItems.m_First;
var secondItem = firstItem.m_Next;
Another option is to make ChainElement a generic interface:
public interface IChainElement<T> where T : IChainElement<T>
{
T Previous { get; set; }
T Next { get; set; }
}
But then you will have to explicitly add the properties to each class you want to put in the list:
public class Entity { }
public class Item : Entity, IChainElement<Item>
{
public Item Previous { get; set; }
public Item Next { get; set; }
}
Either way you end up needing to modify all the classes you want to use in your list.
As an aside, you might want to use a better set of naming conventions. Prefacing all your class names with C, naming parameters and locals with InitialCapitals and public fields starting with m_ make your code pretty hard to read! I would recommend something like this:
public class ChainElement<T> where T : ChainElement<T>
{
public T Previous { get; set; }
public T Next { get; set; }
}
public class ChainList<T> : IEnumerable where T : ChainElement<T>
{
public T First { get; private set; }
public void Add(T element)
{
if (First != null)
First.Previous = element;
element.Next = First;
First = element;
}
public IEnumerator GetEnumerator() { throw new NotImplementedException(); }
}
public class Entity<T> : ChainElement<T> where T : ChainElement<T> { }
public class Item : Entity<Item> { }