/// <summary>
/// Performs a search in the index.
/// </summary>
/// <param name="query">The search query.</param>
/// <param name="documentTypeTags">The document type tags to include in the search.</param>
/// <param name="filterDocumentType"><c>true</c> to apply the filter on the document type.</param>
/// <param name="options">The search options.</param>
/// <param name="fetcher">An object that is able to fetch words.</param>
/// <returns>The results.</returns>
/// <exception cref="ArgumentNullException">If <paramref name="query"/> or <paramref name="fetcher"/> are <c>null</c>.</exception>
/// <exception cref="ArgumentException">If <paramref name="query"/> is empty.</exception>
/// <exception cref="ArgumentNullException">If <paramref name="filterDocumentType"/> is <c>true</c> and <paramref name="documentTypeTags"/> is <c>null</c>.</exception>
/// <exception cref="ArgumentException">If <paramref name="filterDocumentType"/> is <c>true</c> and <paramref name="documentTypeTags"/> is empty.</exception>
public static SearchResultCollection SearchInternal(string query, string[] documentTypeTags, bool filterDocumentType, SearchOptions options, IWordFetcher fetcher)
{
if (query == null)
{
throw new ArgumentNullException("query");
}
if (query.Length == 0)
{
throw new ArgumentException("Query cannot be empty.", "query");
}
if (filterDocumentType && documentTypeTags == null)
{
throw new ArgumentNullException("documentTypeTags");
}
if (filterDocumentType && documentTypeTags.Length == 0)
{
throw new ArgumentException("documentTypeTags cannot be empty.", "documentTypeTags");
}
if (fetcher == null)
{
throw new ArgumentNullException("fetcher");
}
SearchResultCollection results = new SearchResultCollection();
query = query.ToLowerInvariant();
string[] queryWords = query.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
float totalRelevance = 0;
Word word = null;
foreach (string q in queryWords)
{
if (fetcher.TryGetWord(q, out word))
{
foreach (IDocument doc in word.Occurrences.Keys)
{
// Skip documents with excluded tags
if (filterDocumentType &&
!IsDocumentTypeTagIncluded(doc.TypeTag, documentTypeTags))
{
continue;
}
foreach (BasicWordInfo info in word.Occurrences[doc])
{
// If a search result is already present, add a new match to it,
// otherwise create a new search result object
WordInfo mi = new WordInfo(q, info.FirstCharIndex, info.WordIndex, info.Location);
SearchResult res = results.GetSearchResult(doc);
if (res == null)
{
res = new SearchResult(doc);
res.Relevance.SetValue(info.Location.RelativeRelevance);
res.Matches.Add(mi);
results.Add(res);
}
else
{
// Avoid adding duplicate matches (happens when query contains the same word multiple times)
if (!res.Matches.ContainsOccurrence(mi.Text, mi.FirstCharIndex))
{
res.Matches.Add(mi);
}
res.Relevance.SetValue(res.Relevance.Value + info.Location.RelativeRelevance);
}
totalRelevance += info.Location.RelativeRelevance;
}
}
}
}
if (options == SearchOptions.AllWords)
{
totalRelevance -= PurgeResultsForAllWords(results, queryWords);
}
else if (options == SearchOptions.ExactPhrase)
{
totalRelevance -= PurgeResultsForExactPhrase(results, queryWords);
}
else if (options == SearchOptions.AtLeastOneWord)
{
// Nothing to do
}
else
{
throw new InvalidOperationException("Unsupported SearchOptions.");
}
// Finalize relevance values
for (int i = 0; i < results.Count; i++)
{
results[i].Relevance.Finalize(totalRelevance);
}
return(results);
}
/// <summary>
/// Purges the invalid results when SearchOptions is ExactPhrase.
/// </summary>
/// <param name="results">The results to purge.</param>
/// <param name="queryWords">The query words.</param>
/// <returns>The relevance value of the removed matches.</returns>
public static float PurgeResultsForExactPhrase(SearchResultCollection results, string[] queryWords)
{
// Remove results that do not contain the exact phrase
float relevanceToRemove = 0;
List <SearchResult> toRemove = new List <SearchResult>();
foreach (SearchResult r in results)
{
// Shortcut
if (r.Matches.Count < queryWords.Length)
{
toRemove.Add(r);
}
else
{
// Verify that all matches are in the same order as in the query
// and that their indices make up contiguous words,
// re-iterating from every word in the result, for example:
// query = 'repeated content', result = 'content repeated content'
// result must be tested with 'content repeated' (failing) and with 'repeated content' (succeeding)
int maxTestShift = 0;
if (queryWords.Length < r.Matches.Count)
{
maxTestShift = r.Matches.Count - queryWords.Length;
}
bool sequenceFound = false;
for (int shift = 0; shift <= maxTestShift; shift++)
{
int firstWordIndex = r.Matches[shift].WordIndex;
bool allOk = true;
for (int i = 0; i < queryWords.Length; i++)
{
if (queryWords[i] != r.Matches[i + shift].Text.ToLowerInvariant() ||
r.Matches[i + shift].WordIndex != firstWordIndex + i)
{
allOk = false;
break;
}
}
if (allOk)
{
sequenceFound = true;
break;
}
}
if (!sequenceFound)
{
toRemove.Add(r);
}
}
}
foreach (SearchResult r in toRemove)
{
results.Remove(r);
relevanceToRemove += r.Relevance.Value;
}
return(relevanceToRemove);
}