Quickly thrown together Interpolated String Handler based Parser

Parser.cs

using System;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;

namespace ParserTest;

public static class Parser
{
    [InterpolatedStringHandler]
    [StructLayout(LayoutKind.Auto)]
    public ref struct ParseValuesHandler
    {
        private bool successfulSoFar = true;
        private int parsedValuesCount = 0;
        private readonly int valuesToParseCount;
        private ReadOnlySpan<char> charSource;
        private readonly IFormatProvider? formatProvider;

        internal bool Successful => successfulSoFar;
        internal int ParsedValuesCount => parsedValuesCount;

        private bool PointlessToContinue => !successfulSoFar | parsedValuesCount >= valuesToParseCount;

        public ParseValuesHandler(int literalLength, int formattedCount, ReadOnlySpan<char> parsedChars, IFormatProvider? formatProvider = null)
        {
            this.charSource = parsedChars;
            this.valuesToParseCount = formattedCount;
            this.formatProvider = formatProvider;
        }

        public void AppendLiteral(string s)
        {
            if (PointlessToContinue)
            {
                return;
            }

            int literalIndex = charSource.IndexOf(s);
            if (literalIndex < 0)
            {
                successfulSoFar = false;
                return;
            }

            charSource = charSource[(literalIndex + s.Length)..];
        }
        public void AppendFormatted<T>(in T valueToParse) where T : ISpanParseable<T>
        {
            if (PointlessToContinue)
            {
                return;
            }

            if (parsedValuesCount != valuesToParseCount - 1)
            {
                throw new InvalidOperationException("Only the last parsed value is allowed not to have length or separator defined");
            }

            AppendFormatted(valueToParse, charSource.Length);
        }
        public void AppendFormatted<T>(in T valueToParse, string format) where T : ISpanParseable<T>
        {
            string separator = format ?? throw new ArgumentNullException(nameof(format));
            if (PointlessToContinue)
            {
                return;
            }

            int separatorIndex = charSource.IndexOf(separator);
            if (separatorIndex <= 0)
            {
                successfulSoFar = false;
                return;
            }

            AppendFormatted(valueToParse, separatorIndex);

            if (PointlessToContinue)
            {
                return;
            }

            charSource = charSource[separator.Length..];
        }

        public void AppendFormatted<T>(in T valueToParse, int alignment) where T : ISpanParseable<T>
        {
            int length = alignment;
            if (length <= 0)
            {
                throw new ArgumentException("The length of parsed value must be positive", nameof(alignment));
            }
            if (PointlessToContinue)
            {
                return;
            }

            if (T.TryParse(charSource[..length], formatProvider, out Unsafe.AsRef(valueToParse)))
            {
                charSource = charSource[length..];
                parsedValuesCount++;
            }
            else
            {
                successfulSoFar = false;
            }
        }
    }

    [InterpolatedStringHandler]
    [StructLayout(LayoutKind.Auto)]
    public ref struct ParseHomogenousValuesHandler<TParseable> where TParseable : ISpanParseable<TParseable>
    {
        private bool successfulSoFar = true;
        
        private int parsedValuesCount = 0;
        private readonly int valuesToParseCount;

        private int separatorLengthSoFar = 0;
        private readonly int totalSeparatorLength;
        
        private ReadOnlySpan<char> charSource;
        private readonly IFormatProvider? formatProvider;

        private Span<TParseable> nextValueToParse = default;


        internal bool Successful => successfulSoFar;
        internal int ParsedValuesCount => parsedValuesCount;

        private bool PointlessToContinue => !successfulSoFar | parsedValuesCount >= valuesToParseCount;

        public ParseHomogenousValuesHandler(int literalLength, int formattedCount, ReadOnlySpan<char> parsedChars, IFormatProvider? formatProvider = null)
        {
            this.charSource = parsedChars;
            this.valuesToParseCount = formattedCount;
            this.totalSeparatorLength = literalLength;
            this.formatProvider = formatProvider;
        }

        public void AppendLiteral(string s)
        {
            if (PointlessToContinue)
            {
                return;
            }

            separatorLengthSoFar += s.Length;

            int literalIndex = charSource.IndexOf(s);
            if (literalIndex < 0)
            {
                successfulSoFar = false;
                return;
            }


            if (!nextValueToParse.IsEmpty)
            {
                if (TParseable.TryParse(charSource[..literalIndex], formatProvider, out MemoryMarshal.GetReference(nextValueToParse)))
                {
                    parsedValuesCount++;
                }
                else
                {
                    successfulSoFar = false;
                    return;
                }
                nextValueToParse = default;
            }

            charSource = charSource[(literalIndex + s.Length)..];
        }

        public void AppendFormatted(in TParseable valueToParse)
        {
            if (PointlessToContinue)
            {
                return;
            }

            if (!nextValueToParse.IsEmpty)
            {
                throw new InvalidOperationException("Separators between values are needed");
            }

            if (parsedValuesCount == valuesToParseCount - 1 && separatorLengthSoFar >= totalSeparatorLength)
            {
                // if this is the last value to parse but there isn't any literals (separators) left, just format
                // using the rest of charSource
                if (TParseable.TryParse(charSource, formatProvider, out Unsafe.AsRef(valueToParse)))
                {
                    parsedValuesCount++;
                }
                else
                {
                    successfulSoFar = false;
                    return;
                }
            }
            else
            {
                // save the reference to valueToParse so that AppendLiteral can use it
                nextValueToParse = MemoryMarshal.CreateSpan(ref Unsafe.AsRef(valueToParse), 1);
            }
        }
    }

    public static bool TryParseValues(
        ReadOnlySpan<char> source,
        [InterpolatedStringHandlerArgument("source")] ref ParseValuesHandler handler,
        out int parsedValuesCount)
    {
        parsedValuesCount = handler.ParsedValuesCount;
        return handler.Successful;
    }

    public static bool TryParseValues(
        ReadOnlySpan<char> source,
        IFormatProvider? formatProvider,
        [InterpolatedStringHandlerArgument("source", "formatProvider")] ref ParseValuesHandler handler,
        out int parsedValuesCount)
    {
        parsedValuesCount = handler.ParsedValuesCount;
        return handler.Successful;
    }

    public static void ParseValues(
        ReadOnlySpan<char> source,
        [InterpolatedStringHandlerArgument("source")] ref ParseValuesHandler handler)
    {
        if (!handler.Successful)
        {
            throw new ArgumentException("Parsing unsuccessful");
        }
    }

    public static void ParseValues(
        ReadOnlySpan<char> source,
        IFormatProvider? formatProvider,
        [InterpolatedStringHandlerArgument("source", "formatProvider")] ref ParseValuesHandler handler)
    {
        if (!handler.Successful)
        {
            throw new ArgumentException("Parsing unsuccessful");
        }
    }

    public static bool TryParseHomogenousValues<T>(
        ReadOnlySpan<char> source,
        [InterpolatedStringHandlerArgument("source")] ref ParseHomogenousValuesHandler<T> handler,
        out int parsedValuesCount)
        where T : ISpanParseable<T>
    {
        parsedValuesCount = handler.ParsedValuesCount;
        return handler.Successful;
    }

    public static bool TryParseHomogenousValues<T>(
        ReadOnlySpan<char> source,
        IFormatProvider? formatProvider,
        [InterpolatedStringHandlerArgument("source", "formatProvider")] ref ParseHomogenousValuesHandler<T> handler,
        out int parsedValuesCount)
        where T : ISpanParseable<T>
    {
        parsedValuesCount = handler.ParsedValuesCount;
        return handler.Successful;
    }

    public static void ParseHomogenousValues<T>(
        ReadOnlySpan<char> source,
        [InterpolatedStringHandlerArgument("source")] ref ParseHomogenousValuesHandler<T> handler)
        where T : ISpanParseable<T>
    {
        if (!handler.Successful)
        {
            throw new ArgumentException("Parsing unsuccessful");
        }
    }

    public static void ParseHomogenousValues<T>(
        ReadOnlySpan<char> source,
        IFormatProvider? formatProvider,
        [InterpolatedStringHandlerArgument("source", "formatProvider")] ref ParseHomogenousValuesHandler<T> handler)
        where T : ISpanParseable<T>
    {
        if (!handler.Successful)
        {
            throw new ArgumentException("Parsing unsuccessful");
        }
    }
}

Program.cs

using System;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;

using ParserTest;



string versionString = "minor and major: 6 and 0 ... build and revision are 100, 7";

int major = 0, minor = 0, build = 0, revision = 0;

// here, format is used to inform the parser which chars should be after the value, 
// and string literals inbetween are used to inform the parser what chars should be behind each value
Parser.ParseValues(versionString,
    $"major: {major: and} {minor: .} are {build:,} {revision}");

Console.WriteLine($"{major}.{minor}.{build}.{revision}");
// prints "6.0.100.7"

major = minor = build = revision = 0;
// here, format is not used but entire substrings between values 
// have to be specified
Parser.ParseHomogenousValues<int>(versionString,
    $"major: {major} and {minor} ... build and revision are {build}, {revision}");

Console.WriteLine($"{major}.{minor}.{build}.{revision}");
// prints "6.0.100.7"





// mm_YYYY_dd:hh for some reason
string awkwardDateString = "04_2022_23:20";

byte hour = 0, day = 0, month = 0;
int year = 0;

//here, alignment is used to infrom the parser how long each substring is
//this method supports multiple types, so we can use both byte and int
Parser.ParseValues(awkwardDateString, $"{month,2}_{year,4}_{day,2}:{hour,2}");

DateTime date = new(year, month, day, hour, 0, 0);
Console.WriteLine(date.ToString(CultureInfo.InvariantCulture));
// prints 04/23/2022 20:00:00

month = day = hour = 0;
year = 0;
//or if we can't guarantee length of substrings:
Parser.ParseValues(awkwardDateString, $"{month:_}{year:_}{day::}{hour}");

date = new(year, month, day, hour, 0, 0);
Console.WriteLine(date.ToString(CultureInfo.InvariantCulture));
// prints 04/23/2022 20:00:00

year = 0;
int iHour = 0, iDay = 0, iMonth = 0;
//with this method, we can't use ints AND bytes, only one T at a time
Parser.ParseHomogenousValues<int>(awkwardDateString,
    $"{iMonth}_{year}_{iDay}:{iHour}");

date = new(year, month, day, hour, 0, 0);
Console.WriteLine(date.ToString(CultureInfo.InvariantCulture));
// prints 04/23/2022 20:00:00





string someNumbers = "10, 20, 30, 65.984, 8965.1233121231";
int a = 0, b = 0, c = 0;
float e = 0;
double f = 0;

// IFormatProvider can be supplied
Parser.ParseValues(someNumbers, CultureInfo.InvariantCulture,
    $"{a:,} {b:,} {c,2} {e:,} {f}");


Console.WriteLine($"{a + b + c}...{e + f}");
//prints "60...9031,107313282768" on my machine

double v = 0, w = 0, x = 0, y = 0, z = 0;

// can use the 'homogenous' parse method, but the variables
// have to be of the same type
Parser.ParseHomogenousValues<double>(someNumbers, CultureInfo.InvariantCulture,
    $"{v}, {w}, {x}, {y}, {z}");

Console.WriteLine($"{v + w + x}...{y + z}");
//prints "60...9031,1073121231" on my machine







string vectorsString =
    "( 10.5 ; 9e02 ; 98.3 )\n" +
    "( 9999 ; 1111 ; 2e8 )\n" +
    "( 3255 ; .1e6 ; 48.987 )\n";

var vectorsArray = new Vector3[3];

Parser.ParseHomogenousValues<Vector3>(vectorsString, CultureInfo.InvariantCulture,
    $"{vectorsArray[0]}\n{vectorsArray[1]}\n{vectorsArray[2]}");

foreach (var vec in vectorsArray)
{
    Console.WriteLine(vec);
}
/*
prints
( 10,5 ; 900 ; 98,3 )
( 9999 ; 1111 ; 200000000 )
( 3255 ; 100000 ; 48,987 )
*/



struct Vector3 : ISpanParseable<Vector3>
{
    private float x, y, z;

    public static Vector3 Parse(ReadOnlySpan<char> s, IFormatProvider? provider)
    {
        throw new NotImplementedException();
    }

    public static Vector3 Parse(string s, IFormatProvider? provider)
    {
        throw new NotImplementedException();
    }

    public static bool TryParse(ReadOnlySpan<char> s, IFormatProvider? provider, out Vector3 result)
    {
        result = new Vector3();
        ref float
            x = ref result.x,
            y = ref result.y,
            z = ref result.z;

        return Parser.TryParseHomogenousValues<float>(s, provider,
            $"( {x} ; {y} ; {z} )", out _);
    }

    public static bool TryParse([NotNullWhen(true)] string? s, IFormatProvider? provider, out Vector3 result)
    {
        throw new NotImplementedException();
    }

    public override string ToString() => $"( {x} ; {y} ; {z} )";
}

https://www.reddit.com/r/csharp/comments/uacz1s/this_is_really_cool_in_c_11_thanks_to_static/