private static int ParseArraySpecifier(ref BufferReader s)
        {
            s.ConsumeCharacter(ArrayStartIndicator);
            var dimensions = 1;

            while (s.TryPeek(out var c) && c != ArrayEndIndicator)
            {
                s.ConsumeCharacter(ArrayDimensionIndicator);
                ++dimensions;
            }

            s.ConsumeCharacter(ArrayEndIndicator);
            return(dimensions);
        }
        private static ReadOnlySpan <char> ParseTypeName(ref BufferReader s)
        {
            var start             = s.Index;
            var typeName          = ParseSpan(ref s, TypeNameDelimiters);
            var genericArityStart = -1;

            while (s.TryPeek(out char c))
            {
                if (genericArityStart < 0 && c == GenericTypeIndicator)
                {
                    genericArityStart = s.Index + 1;
                }
                else if (genericArityStart < 0 || !char.IsDigit(c))
                {
                    break;
                }

                s.ConsumeCharacter(c);
            }

            if (genericArityStart >= 0)
            {
                // The generic arity is additive, so that a generic class nested in a generic class has an arity
                // equal to the sum of specified arity values. For example, "C`1+N`2" has an arity of 3.
                var aritySlice = s.Input.Slice(genericArityStart, s.Index - genericArityStart);
#if NETCOREAPP
                var arity = int.Parse(aritySlice);
#else
                var arity = int.Parse(aritySlice.ToString());
#endif
                s.TotalGenericArity += arity;
                if (s.TotalGenericArity > MaxAllowedGenericArity)
                {
                    ThrowGenericArityTooLarge(s.TotalGenericArity);
                }

                // Include the generic arity in the type name.
                typeName = s.Input.Slice(start, s.Index - start);
            }

            return(typeName);
        }
        private static TypeSpec ParseInternal(ref ReadOnlySpan <char> input)
        {
            TypeSpec     result;
            char         c;
            BufferReader s = default;

            s.Input = input;

            // Read namespace and class name, including generic arity, which is a part of the class name.
            NamedTypeSpec named = null;

            while (true)
            {
                var typeName = ParseTypeName(ref s);
                named = new NamedTypeSpec(named, typeName.ToString(), s.TotalGenericArity);

                if (s.TryPeek(out c) && c == NestedTypeIndicator)
                {
                    // Consume the nested type indicator, then loop to parse the nested type.
                    s.ConsumeCharacter(NestedTypeIndicator);
                    continue;
                }

                break;
            }

            // Parse generic type parameters
            if (s.TotalGenericArity > 0 && s.TryPeek(out c) && c == ArrayStartIndicator)
            {
                s.ConsumeCharacter(ArrayStartIndicator);

                var arguments = new TypeSpec[s.TotalGenericArity];
                for (var i = 0; i < s.TotalGenericArity; i++)
                {
                    if (i > 0)
                    {
                        s.ConsumeCharacter(ParameterSeparator);
                    }

                    // Parse the argument type
                    s.ConsumeCharacter(ArrayStartIndicator);
                    var remaining = s.Remaining;
                    arguments[i] = ParseInternal(ref remaining);
                    var consumed = s.Remaining.Length - remaining.Length;
                    s.Consume(consumed);
                    s.ConsumeCharacter(ArrayEndIndicator);
                }

                s.ConsumeCharacter(ArrayEndIndicator);
                result = new ConstructedGenericTypeSpec(named, arguments);
            }
            else
            {
                // This is not a constructed generic type
                result = named;
            }

            // Parse modifiers
            bool hadModifier;

            do
            {
                hadModifier = false;

                if (!s.TryPeek(out c))
                {
                    break;
                }

                switch (c)
                {
                case ArrayStartIndicator:
                    var dimensions = ParseArraySpecifier(ref s);
                    result      = new ArrayTypeSpec(result, dimensions);
                    hadModifier = true;
                    break;

                case PointerIndicator:
                    result = new PointerTypeSpec(result);
                    s.ConsumeCharacter(PointerIndicator);
                    hadModifier = true;
                    break;

                case ReferenceIndicator:
                    result = new ReferenceTypeSpec(result);
                    s.ConsumeCharacter(ReferenceIndicator);
                    hadModifier = true;
                    break;
                }
            } while (hadModifier);

            // Extract the assembly, if specified.
            if (s.TryPeek(out c) && c == AssemblyIndicator)
            {
                s.ConsumeCharacter(AssemblyIndicator);
                var assembly = ExtractAssemblySpec(ref s);
                result = new AssemblyQualifiedTypeSpec(result, assembly.ToString());
            }

            input = s.Remaining;
            return(result);
        }