Word forms provider Leave feedback
The IWordFormsProvider interface is designed to implement a word forms provider for searching by word forms. For information on searching by word forms, see the Search for different word forms page.
The IWordFormsProvider interface contains only one GetWordForms method, which returns various forms for the word passed as an argument. An example implementation of a simple provider of word forms is presented below.
C#
public class SimpleWordFormsProvider : IWordFormsProvider
{
public string[] GetWordForms(string word)
{
List<string> result = new List<string>();
// We assume that the input word is in the plural, then we add the singular
if (word.Length > 3 &&
word.EndsWith("ies", StringComparison.InvariantCultureIgnoreCase))
{
result.Add(word.Substring(0, word.Length - 3) + "y");
}
if (word.Length > 2 &&
word.EndsWith("es", StringComparison.InvariantCultureIgnoreCase))
{
result.Add(word.Substring(0, word.Length - 2));
}
if (word.Length > 1 &&
word.EndsWith("s", StringComparison.InvariantCultureIgnoreCase))
{
result.Add(word.Substring(0, word.Length - 1));
}
// Then we assume that the input word is in the singular, we add the plural
if (word.Length > 1 &&
word.EndsWith("y", StringComparison.InvariantCultureIgnoreCase))
{
result.Add(word.Substring(0, word.Length - 1) + "ies");
}
else if (word.EndsWith("s", StringComparison.InvariantCultureIgnoreCase) ||
word.EndsWith("x", StringComparison.InvariantCultureIgnoreCase) ||
word.EndsWith("ch", StringComparison.InvariantCultureIgnoreCase) ||
word.EndsWith("sh", StringComparison.InvariantCultureIgnoreCase))
{
result.Add(word + "es");
}
else
{
result.Add(word + "s");
}
// All rules are implemented in the EnglishWordFormsProvider class
return result.ToArray();
}
}
By default, the EnglishWordFormsProvider class is used, which for English generates various forms of nouns, adjectives, pronouns, verbs, etc. A custom provider is set with the WordFormsProvider property of the Index.Dictionaries object. The provider can be replaced at any time; it is not saved in the index, so it must be set each time the index is opened. An example of setting a custom provider of word forms is presented below.
C#
string indexFolder = @"c:\MyIndex\";
string documentsFolder = @"c:\MyDocuments\";
// Creating or opening an index in the specified folder
Index index = new Index(indexFolder);
// Indexing documents from the specified folder
index.Add(documentsFolder);
// Setting the custom word forms provider instance
index.Dictionaries.WordFormsProvider = new SimpleWordFormsProvider();
// Creating a search options instance
SearchOptions options = new SearchOptions();
options.UseWordFormsSearch = true; // Enabling search for word forms
// Searching in the index
SearchResult result = index.Search("relative", options);
// The following words can be found:
// relative
// relatives
You may easily run the code from documentation articles and see the features in action in our GitHub examples:
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You are welcome to search over your PDF, DOC, DOCX, PPT, PPTX, XLS, XLSX and more with our free online Free Online Document Search App.
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