public static SearchIndex <TType> Build <TType>(IEnumerable <TType> source, SearchIndexOptions <TType> options)
{
if (!options.Properties.Any())
{
throw new Exception($"No properties specified to index");
}
var wordFrequency = new Dictionary <string, int>();
var index = new SearchIndex <TType>
{
Options = options,
Source = source.Select(c => IndexItem(c, options, wordFrequency)).ToList()
};
// Index the top 1% of common words to give low scores too
var possibleCommonWords = wordFrequency.Where(w => w.Value > 2);
index.CommonWords = possibleCommonWords.OrderByDescending(c => c.Value).Take(possibleCommonWords.Count() / 100).Select(w => w.Key).ToArray();
return(index);
}
private static SearchItem <TType> IndexItem <TType>(TType item, SearchIndexOptions <TType> options, Dictionary <string, int> wordFrequency)
{
var index = new SearchItem <TType>(item);
foreach (var property in options.Properties)
{
var propertyValues = property.Value.Func.Invoke(item)?.Split(' ').Select(x => x.Clean());
if (propertyValues == null || !propertyValues.Any())
{
continue;
}
foreach (var word in propertyValues)
{
if (word.Length > 2)
{
if (wordFrequency.ContainsKey(word))
{
wordFrequency[word]++;
}
else
{
wordFrequency.Add(word, 1);
}
}
}
var propertyIndexValue = string.Join(options.IndexSeperator, propertyValues);
if (!string.IsNullOrEmpty(propertyIndexValue))
{
index.Index += $"{options.IndexSeperator}{propertyIndexValue}{options.IndexSeperator}";
index.PropertyIndexMap.Add(property.Key, index.Index.Length - 1);
}
}
return(index);
}
public static SearchIndex <TType> Build <TType>(IEnumerable <TType> source)
{
var options = new SearchIndexOptions <TType>();
return(Build(source, options));
}
public static SearchIndex <TType> ReBuild <TType>(SearchIndex <TType> original, ObservableCollection <TType> source, SearchIndexOptions <TType> options)
{
return(original);
}