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•Created by potzko on 3/9/2024 in #help

help with generic interface

im writing a small binary tree library for fun and ran into a small problem I made a small interface for Node and Tree: however the Node interface can only reference itself if that makes sense? public interface Node<T> where T : IComparable<T>

public interface Node<T> where T : IComparable<T>
{
    T GetValue();
    Node<T>? Getleft();
    Node<T>? GetRight();
}

public class SplayTreeNode<T> : Node<T> where T : IComparable<T>
{
    private T data;
    private SplayTreeNode<T>? left;
    private SplayTreeNode<T>? right;
    private SplayTreeNode<T>? parent;

    public SplayTreeNode(T value)
    {
        data = value;
    }

    public T GetValue()
    {
        return data;
    }

    public SplayTreeNode<T>? Getleft()
    {
        return left;
    }

    public SplayTreeNode<T>? GetRight()
    {
        return right;
    }
}

public interface Node<T> where T : IComparable<T>
{
    T GetValue();
    Node<T>? Getleft();
    Node<T>? GetRight();
}

public class SplayTreeNode<T> : Node<T> where T : IComparable<T>
{
    private T data;
    private SplayTreeNode<T>? left;
    private SplayTreeNode<T>? right;
    private SplayTreeNode<T>? parent;

    public SplayTreeNode(T value)
    {
        data = value;
    }

    public T GetValue()
    {
        return data;
    }

    public SplayTreeNode<T>? Getleft()
    {
        return left;
    }

    public SplayTreeNode<T>? GetRight()
    {
        return right;
    }
}

75 replies

CC#

•Created by potzko on 1/2/2024 in #help

C# enum deconstruction and assosiated data

hi, I want to follow the book crafting interpreters and I don't want to use the exact languadge he uses (java) to avoid copy pasting code without understanding it, I am looking at maybe using C# (I know... super far away from java), however I can't find a feature Ill prob want to use, is there a way to do rust style enum types with associated data? think something like (super super psudo code)

enum a{
twoDimantionalVector: (int, int)
position: (int, int, int)
cat: (string, string, int)
}
a value = ...
match a {
  case twoDimantionalVector(X, Y);
  case position(X, Y, Z) {...}
  case cat(name, color, age);
}

enum a{
twoDimantionalVector: (int, int)
position: (int, int, int)
cat: (string, string, int)
}
a value = ...
match a {
  case twoDimantionalVector(X, Y);
  case position(X, Y, Z) {...}
  case cat(name, color, age);
}

8 replies

CC#

•Created by potzko on 5/12/2023 in #help

❔ help with self referential class typing

I was trying to make a node class I can inherit from and ran into a ton of trouble, in my original solution the "next" value was still a node rather then the child class, I looked around and people were saying to use a self referential generic class signature so I used this:

public class Node<Self, T>
where Self: Node<Self, T> 
{
    public T value;
    public Self? next;
}

public class Node<Self, T>
where Self: Node<Self, T> 
{
    public T value;
    public Self? next;
}

and started writing, I even got some inheritance to work,

public class CmpNode<T>: Node<CmpNode<T>, T>
where T: IComparable
{
    public CmpNode(T value) : base(value) { }
    public CmpNode(T value, CmpNode<T> next) : base(value, next) { }

    public CmpNode<T> getMaxNode(){
        var max = this;
        var point = this;
        while (point!.hasNext()){
            if (max.value.CompareTo(point.value) == -1){
                max = point;
            }
            point = point.next;
        }
        if (max.value.CompareTo(point.value) == -1){
            max = point;
        }
        return max;
    }
}

public class CmpNode<T>: Node<CmpNode<T>, T>
where T: IComparable
{
    public CmpNode(T value) : base(value) { }
    public CmpNode(T value, CmpNode<T> next) : base(value, next) { }

    public CmpNode<T> getMaxNode(){
        var max = this;
        var point = this;
        while (point!.hasNext()){
            if (max.value.CompareTo(point.value) == -1){
                max = point;
            }
            point = point.next;
        }
        if (max.value.CompareTo(point.value) == -1){
            max = point;
        }
        return max;
    }
}

however I ran into a few problems in some of the functions:

    public static Self? fromArr(T[] arr){
        if (arr.Length == 0){
            return null;
        } 
        var start = new Self(arr[0]);
        var point = start;
        foreach (T item in arr.Skip(1))
        {    
            point.next = new Self(item);
        }
        return start;    
    }

    public static Self? fromArr(T[] arr){
        if (arr.Length == 0){
            return null;
        } 
        var start = new Self(arr[0]);
        var point = start;
        foreach (T item in arr.Skip(1))
        {    
            point.next = new Self(item);
        }
        return start;    
    }

in this function for example, how can I make a new "Self" object? as I do not know what constructors it has. and if I try to build a node I cant set it as next as I expect a Self object, am I missing a trick to get this to work?

9 replies

CC#

•Created by potzko on 3/23/2023 in #help

❔ id love to get a code review if possible

this is a segmented sieve code I wrote. it is meant to be as fast as I can get it, however id mostly like to get coding conventions for cs down

using System.Collections;
using System.Collections.Generic;

public class Primes
{
    static List<int> primes = new List<int>(new int[] { 2, 3, 5, 7 });
    static int segment = 1;
    public static void add_next_seg()
    {
        // use segmented sieve to add numbers to the prime list.
        
        //the next primes for whom we will check the squared segment
        int start = Primes.primes[Primes.segment];
        int end = Primes.primes[Primes.segment + 1];

        //create the bounds of the segment
        int seg_start = start * start;
        int seg_end = end * end;
        //create the segment, false -> prime, true -> composite
        bool[] seg = new bool[seg_end - seg_start];
        
        //the max number is seg_end which is end**2 -> only need to check primes under and including end.
        //no need to check 2, as we will jump by 2 when adding the numbers later
        for (int i = 1; i < segment + 1; i++) {
            int prime_num = Primes.primes[i];
            //start at start of segment and mark all numbers devisible by the prime number
            for (int ind = seg_start + (prime_num - (seg_start%prime_num))%prime_num; ind - seg_start < seg.Length; ind += prime_num)
            {
                seg[ind - seg_start] = true;
            }
        }
        
        //no need to check 2, as we precoded first iteration, -> start != 2 -> seg_start is odd
        for (int ind = seg_start; ind < seg_end; ind+=2)
        {
            if (!seg[ind - seg_start])
            {
                Primes.primes.Add(ind);
            }
        }
        Primes.segment++;
    }
    public static int get_nth_prime(int ind){
        //returns the nth prime
        while (Primes.primes.Count <= ind){
            Primes.add_next_seg();
        }
        return Primes.primes[ind];
    }
}

using System.Collections;
using System.Collections.Generic;

public class Primes
{
    static List<int> primes = new List<int>(new int[] { 2, 3, 5, 7 });
    static int segment = 1;
    public static void add_next_seg()
    {
        // use segmented sieve to add numbers to the prime list.
        
        //the next primes for whom we will check the squared segment
        int start = Primes.primes[Primes.segment];
        int end = Primes.primes[Primes.segment + 1];

        //create the bounds of the segment
        int seg_start = start * start;
        int seg_end = end * end;
        //create the segment, false -> prime, true -> composite
        bool[] seg = new bool[seg_end - seg_start];
        
        //the max number is seg_end which is end**2 -> only need to check primes under and including end.
        //no need to check 2, as we will jump by 2 when adding the numbers later
        for (int i = 1; i < segment + 1; i++) {
            int prime_num = Primes.primes[i];
            //start at start of segment and mark all numbers devisible by the prime number
            for (int ind = seg_start + (prime_num - (seg_start%prime_num))%prime_num; ind - seg_start < seg.Length; ind += prime_num)
            {
                seg[ind - seg_start] = true;
            }
        }
        
        //no need to check 2, as we precoded first iteration, -> start != 2 -> seg_start is odd
        for (int ind = seg_start; ind < seg_end; ind+=2)
        {
            if (!seg[ind - seg_start])
            {
                Primes.primes.Add(ind);
            }
        }
        Primes.segment++;
    }
    public static int get_nth_prime(int ind){
        //returns the nth prime
        while (Primes.primes.Count <= ind){
            Primes.add_next_seg();
        }
        return Primes.primes[ind];
    }
}

248 replies

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