Jazz Up Your C# Code

#region License
// Copyright (c) 2007 James Newton-King
//
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without
// restriction, including without limitation the rights to use,
// copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following
// conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
#endregion

using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Globalization;
#if NET20
using Newtonsoft.Json.Utilities.LinqBridge;
#else
using System.Linq;
#endif
using Newtonsoft.Json.Serialization;

namespace Newtonsoft.Json.Utilities
{
  internal static class StringUtils
  {
    public const string CarriageReturnLineFeed = "\r\n";
    public const string Empty = "";
    public const char CarriageReturn = '\r';
    public const char LineFeed = '\n';
    public const char Tab = '\t';

    public static string FormatWith(this string format, IFormatProvider provider, params object[] args)
    {
      ValidationUtils.ArgumentNotNull(format, "format");

      return string.Format(provider, format, args);
    }

    /// <summary>
    /// Determines whether the string is all white space. Empty string will return false.
    /// </summary>
    /// <param name="s">The string to test whether it is all white space.</param>
    /// <returns>
    /// 	<c>true</c> if the string is all white space; otherwise, <c>false</c>.
    /// </returns>
    public static bool IsWhiteSpace(string s)
    {
      if (s == null)
        throw new ArgumentNullException("s");

      if (s.Length == 0)
        return false;

      for (int i = 0; i < s.Length; i++)
      {
        if (!char.IsWhiteSpace(s[i]))
          return false;
      }

      return true;
    }

    /// <summary>
    /// Nulls an empty string.
    /// </summary>
    /// <param name="s">The string.</param>
    /// <returns>Null if the string was null, otherwise the string unchanged.</returns>
    public static string NullEmptyString(string s)
    {
      return (string.IsNullOrEmpty(s)) ? null : s;
    }

    public static StringWriter CreateStringWriter(int capacity)
    {
      StringBuilder sb = new StringBuilder(capacity);
      StringWriter sw = new StringWriter(sb, CultureInfo.InvariantCulture);

      return sw;
    }

    public static int? GetLength(string value)
    {
      if (value == null)
        return null;
      else
        return value.Length;
    }

    public static string ToCharAsUnicode(char c)
    {
      char h1 = MathUtils.IntToHex((c >> 12) & '\x000f');
      char h2 = MathUtils.IntToHex((c >> 8) & '\x000f');
      char h3 = MathUtils.IntToHex((c >> 4) & '\x000f');
      char h4 = MathUtils.IntToHex(c & '\x000f');

      return new string(new[] { '\\', 'u', h1, h2, h3, h4 });
    }

    public static TSource ForgivingCaseSensitiveFind<TSource>(this IEnumerable<TSource> source, Func<TSource, string> valueSelector, string testValue)
    {
      if (source == null)
        throw new ArgumentNullException("source");
      if (valueSelector == null)
        throw new ArgumentNullException("valueSelector");

      var caseInsensitiveResults = source.Where(s => string.Equals(valueSelector(s), testValue, StringComparison.OrdinalIgnoreCase));
      if (caseInsensitiveResults.Count() <= 1)
      {
        return caseInsensitiveResults.SingleOrDefault();
      }
      else
      {
        // multiple results returned. now filter using case sensitivity
        var caseSensitiveResults = source.Where(s => string.Equals(valueSelector(s), testValue, StringComparison.Ordinal));
        return caseSensitiveResults.SingleOrDefault();
      }
    }

    public static string ToCamelCase(string s)
    {
      if (string.IsNullOrEmpty(s))
        return s;

      if (!char.IsUpper(s[0]))
        return s;

      string camelCase = null;
#if !NETFX_CORE
      camelCase = char.ToLower(s[0], CultureInfo.InvariantCulture).ToString(CultureInfo.InvariantCulture);
#else
      camelCase = char.ToLower(s[0]).ToString();
#endif

      if (s.Length > 1)
        camelCase += s.Substring(1);

      return camelCase;
    }

    public static bool IsHighSurrogate(char c)
    {
#if !SILVERLIGHT
      return char.IsHighSurrogate(c);
#else
      return (c >= 55296 && c <= 56319);
#endif
    }

    public static bool IsLowSurrogate(char c)
    {
#if !SILVERLIGHT
      return char.IsLowSurrogate(c);
#else
      return (c >= 56320 && c <= 57343);
#endif
    }
  }
}