Extensions.cs

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

namespace StableNameDotNet;

public static class Extensions
{
    public static bool ContainsAnyInvalidSourceCodeChars(this string s, bool allowCompilerGenerated = false)
    {
        foreach (var c in s)
            switch (c)
            {
                case >= 'a' and <= 'z':
                case >= 'A' and <= 'Z':
                case >= '0' and <= '9':
                case '_' or '`':
                case '.' or '<' or '>' when allowCompilerGenerated:
                    continue;
                default:
                    return true;
            }

        return false;
    }

    public static TValue GetOrCreate<TKey, TValue>(this Dictionary<TKey, TValue> dict, TKey key, Func<TValue> defaultGetter) where TKey : notnull
    {
        if (dict.TryGetValue(key, out var value))
            return value;

        value = defaultGetter();
        dict.Add(key, value);
        return value;
    }

    public static string Join(this IEnumerable<string> strings, string separator = "")
        => string.Join(separator, strings);


    public static ulong StableHash(this string str)
        => str.Aggregate<char, ulong>(0, (current, c) => current * 37 + c);
}