RavenDB - An Introduction

// Copyright 2004-2010 Castle Project - http://www.castleproject.org/
// 
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// 
//     http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

using System.Collections;
using System.Text.RegularExpressions;

namespace Raven.Client.Util
{
	/// <summary>
	/// The Inflector class transforms words from one 
	/// form to another. For example, from singular to plural.
	/// </summary>
	public class Inflector
	{
		private static readonly ArrayList plurals = new ArrayList();
		private static readonly ArrayList singulars = new ArrayList();
		private static readonly ArrayList uncountables = new ArrayList();

		private Inflector()
		{
		}

		#region Default Rules

		static Inflector()
		{
			AddPlural("$", "s");
			AddPlural("s$", "s");
			AddPlural("(ax|test)is$", "$1es");
			AddPlural("(octop|vir)us$", "$1i");
			AddPlural("(alias|status)$", "$1es");
			AddPlural("(bu)s$", "$1ses");
			AddPlural("(buffal|tomat)o$", "$1oes");
			AddPlural("([ti])um$", "$1a");
			AddPlural("sis$", "ses");
			AddPlural("(?:([^f])fe|([lr])f)$", "$1$2ves");
			AddPlural("(hive)$", "$1s");
			AddPlural("([^aeiouy]|qu)y$", "$1ies");
			AddPlural("(x|ch|ss|sh)$", "$1es");
			AddPlural("(matr|vert|ind)ix|ex$", "$1ices");
			AddPlural("([m|l])ouse$", "$1ice");
			AddPlural("^(ox)$", "$1en");
			AddPlural("(quiz)$", "$1zes");

			AddSingular("s$", "");
			AddSingular("(n)ews$", "$1ews");
			AddSingular("([ti])a$", "$1um");
			AddSingular("((a)naly|(b)a|(d)iagno|(p)arenthe|(p)rogno|(s)ynop|(t)he)ses$", "$1$2sis");
			AddSingular("(^analy)ses$", "$1sis");
			AddSingular("([^f])ves$", "$1fe");
			AddSingular("(hive)s$", "$1");
			AddSingular("(tive)s$", "$1");
			AddSingular("([lr])ves$", "$1f");
			AddSingular("([^aeiouy]|qu)ies$", "$1y");
			AddSingular("(s)eries$", "$1eries");
			AddSingular("(m)ovies$", "$1ovie");
			AddSingular("(x|ch|ss|sh)es$", "$1");
			AddSingular("([m|l])ice$", "$1ouse");
			AddSingular("(bus)es$", "$1");
			AddSingular("(o)es$", "$1");
			AddSingular("(shoe)s$", "$1");
			AddSingular("(cris|ax|test)es$", "$1is");
			AddSingular("(octop|vir)i$", "$1us");
			AddSingular("(alias|status)es$", "$1");
			AddSingular("^(ox)en", "$1");
			AddSingular("(vert|ind)ices$", "$1ex");
			AddSingular("(matr)ices$", "$1ix");
			AddSingular("(quiz)zes$", "$1");

			AddIrregular("person", "people");
			AddIrregular("man", "men");
			AddIrregular("child", "children");
			AddIrregular("sex", "sexes");
			AddIrregular("move", "moves");

			AddUncountable("equipment");
			AddUncountable("information");
			AddUncountable("rice");
			AddUncountable("money");
			AddUncountable("species");
			AddUncountable("series");
			AddUncountable("fish");
			AddUncountable("sheep");
		}

		#endregion

		#region Rule inner class

		private class Rule
		{
			private readonly Regex regex;
			private readonly string replacement;

			public Rule(string pattern, string replacement)
			{
				regex = new Regex(pattern, RegexOptions.IgnoreCase);
				this.replacement = replacement;
			}

			public string Apply(string word)
			{
				if (!regex.IsMatch(word))
				{
					return null;
				}

				return regex.Replace(word, replacement);
			}
		}

		#endregion

		/// <summary>
		/// Return the plural of a word.
		/// </summary>
		/// <param name="word">The singular form</param>
		/// <returns>The plural form of <paramref name="word"/></returns>
		public static string Pluralize(string word)
		{
			return ApplyRules(plurals, word);
		}

		/// <summary>
		/// Return the singular of a word.
		/// </summary>
		/// <param name="word">The plural form</param>
		/// <returns>The singular form of <paramref name="word"/></returns>
		public static string Singularize(string word)
		{
			return ApplyRules(singulars, word);
		}

		/// <summary>
		/// Capitalizes a word.
		/// </summary>
		/// <param name="word">The word to be capitalized.</param>
		/// <returns><paramref name="word"/> capitalized.</returns>
		public static string Capitalize(string word)
		{
			return word.Substring(0, 1).ToUpper() + word.Substring(1).ToLower();
		}

		private static void AddIrregular(string singular, string plural)
		{
			AddPlural("(" + singular[0] + ")" + singular.Substring(1) + "$", "$1" + plural.Substring(1));
			AddSingular("(" + plural[0] + ")" + plural.Substring(1) + "$", "$1" + singular.Substring(1));
		}

		private static void AddUncountable(string word)
		{
			uncountables.Add(word.ToLower());
		}

		private static void AddPlural(string rule, string replacement)
		{
			plurals.Add(new Rule(rule, replacement));
		}

		private static void AddSingular(string rule, string replacement)
		{
			singulars.Add(new Rule(rule, replacement));
		}

		private static string ApplyRules(IList rules, string word)
		{
			string result = word;

			if (!uncountables.Contains(word.ToLower()))
			{
				for (int i = rules.Count - 1; i >= 0; i--)
				{
					Rule rule = (Rule)rules[i];

					if ((result = rule.Apply(word)) != null)
					{
						break;
					}
				}
			}

			return result;
		}
	}
}