AST грамматики динамически расширяемого парсера

Rules.cs

public abstract record Rule(string Kind)
{
    public abstract override string ToString();
    public virtual Rule InlineReferences(Dictionary<string, Rule> inlineableRules) => this;
}

public abstract record Terminal(string Kind) : Rule(Kind)
{
    public override Rule InlineReferences(Dictionary<string, Rule> inlineableRules) => this;
    public abstract int TryMatch(string input, int position);
}

public sealed record Literal(string Value, string? Kind = null) : Terminal(Kind ?? Value)
{
    public override Rule InlineReferences(Dictionary<string, Rule> inlineableRules) => this;
    public override int TryMatch(string input, int position) =>
        input.AsSpan(position).StartsWith(Value, StringComparison.Ordinal) ? Value.Length : 0;
}

public record Seq(Rule[] Elements, string Kind) : Rule(Kind)
{
    public override string ToString() => string.Join(" ", Elements.Select(e => e is Choice ? $"({e})" : e.ToString()));
    public override Rule InlineReferences(Dictionary<string, Rule> inlineableRules) =>
        new Seq(Elements.Select(e => e.InlineReferences(inlineableRules)).ToArray(), Kind);
}

public record Choice(Rule[] Alternatives, string? Kind = null) : Rule(Kind ?? nameof(Choice))
{
    public override string ToString() => string.Join<Rule>(" | ", Alternatives);
    public override Rule InlineReferences(Dictionary<string, Rule> inlineableRules) =>
        new Choice(Alternatives.Select(a => a.InlineReferences(inlineableRules)).ToArray(), Kind);
}

public record OneOrMany(Rule Element, string? Kind = null) : Rule(Kind ?? nameof(OneOrMany))
{
    public override string ToString() => $"{Element}+";
    public override Rule InlineReferences(Dictionary<string, Rule> inlineableRules) =>
        new OneOrMany(Element.InlineReferences(inlineableRules), Kind);
}

public record ZeroOrMany(Rule Element, string? Kind = null) : Rule(Kind ?? nameof(ZeroOrMany))
{
    public override string ToString() => $"{Element}*";
    public override Rule InlineReferences(Dictionary<string, Rule> inlineableRules) =>
        new ZeroOrMany(Element.InlineReferences(inlineableRules), Kind);
}

public record Optional(Rule Element, string? Kind = null) : Rule(Kind ?? nameof(Optional))
{
    public override string ToString() => $"{Element}?";
    public override Rule InlineReferences(Dictionary<string, Rule> inlineableRules) =>
        new Optional(Element.InlineReferences(inlineableRules), Kind);
}

public record Ref(string RuleName, string? Kind = null) : Rule(Kind ?? nameof(RuleName))
{
    public override string ToString() => RuleName;
    public override Rule InlineReferences(Dictionary<string, Rule> inlineableRules) =>
        inlineableRules.TryGetValue(RuleName, out var rule) ? rule.InlineReferences(inlineableRules) : this;
}

public record ReqRef(string RuleName, int Precedence = 0, bool Right = false, string? Kind = null) : Rule(Kind ?? nameof(RuleName))
{
    public override string ToString() => $"{RuleName} {{{Precedence}, {(Right ? "left" : "right")}}}";
    public override Rule InlineReferences(Dictionary<string, Rule> inlineableRules) => this;
}

public record RuleWithPrecedence(string Kind, Seq Seq, int Precedence, bool Right);

public record TdoppRule(
    Ref Name,
    string Kind,
    Rule[] Prefix,
    RuleWithPrecedence[] Postfix
) : Rule(Kind)
{
    public override string ToString() =>
        $"{Name} = Prefix: {string.Join<Rule>(" | ", Prefix)}" +
        $" Postfix: {string.Join("", Postfix.Select(x => $" {{{x.Precedence}{(x.Right ? "" : " right")}}} {x.Seq}"))}";
}