FmtChk.cs

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using Mercury.Scanning;
using System;
using System.Collections.Generic;
using System.Linq;

namespace Mercury.Formats
{
    internal static class FmtChk
    {
        public static void AssertCount<T>(int count, ICollection<T> collection, string message = null)
        {
            if (count > collection.Count)
                throw new FormatException(message ?? "Not enough elements in collection");
        }

        public static void AssertNotEmpty<T>(ICollection<T> collection, string message = null)
        {
            AssertCount(1, collection, message ?? "Collection is empty");
        }

        public static void AssertNotNull(object obj, string message)
        {
            if (obj == null)
                throw new ArgumentNullException("message");
        }

        public static void AssertToken(Token token, string value, string message = null)
        {
            if (token.Value != value)
                throw new FormatException(message ?? string.Format("Expected '{0}', got '{1}'", value, token.Value));
        }

        public static void AssertPattern<T>(ICollection<T> pattern, ICollection<T> source, string message = null)
        {
            if (pattern.Count > source.Count)
                throw new FormatException(message ?? "Invalid sequence");

            Func<T, T, bool> f = (l, r) =>
            {
                if ((l != null) && (!l.Equals(r)))
                    throw new FormatException(message ?? string.Format("Expected '{0}', got '{1}'", l, r));

                return true;
            };

            pattern.Zip(source, f);
        }

        public static void AssertPattern<T,U>(ICollection<T> pattern, ICollection<U> source, Func<U,T> convert, string message = null)
        {
            if (pattern.Count > source.Count)
                throw new FormatException(message ?? "Invalid sequence");

            AssertPattern(pattern, source.Take(pattern.Count).Select(convert).ToArray(), message);
        }

        public static void AssertTrue(bool condition, string message)
        {
            if (!condition) throw new FormatException(message);
        }

        public static void AssertFalse(bool condition, string message)
        {
            if (condition) throw new FormatException(message);
        }
    }
}