/// <summary>
/// 搜尋主體
/// </summary>
/// <param name="keyword"></param>
/// <param name="fetchSize"></param>
/// <returns></returns>
public SearchResult Search(Repository repo, String keyword, int fetchSize)
{
try
{
return Search(repo, keyword, 0, fetchSize);
}
catch (Exception e)
{
return null;
}
}
/// <summary>
/// 新增索引庫
/// </summary>
/// <param name="name"></param>
/// <returns></returns>
public Repository CreateRepository(String name)
{
try
{
if (this.Repositories.ContainsKey(name))
return Repositories[name];
else
{
try
{
// 新增 repository 資訊
Repository repo = new Repository(this, name);
this.Repositories.Add(name, repo);
// 將 repository 資訊寫入 MongoDB 中
var server = MongoDbLib.GetServerConnection(MongoDbServer);
var database = server.GetDatabase(DbName);
var tblRepos = database.GetCollection<RepositoryInfo>(Constants.TblRepository);
tblRepos.Insert(new RepositoryInfo()
{
Name = name
});
return repo;
}
catch (Exception e)
{
// roll back
if (this.Repositories.ContainsKey(name))
this.Repositories.Remove(name);
throw e;
}
}
}
catch (Exception e)
{
throw e;
}
}
public SearchResult Search(Repository repo, String keyword, int startPos, int fetchSize)
{
try
{
SearchResult result = new SearchResult();
// 計時器
Stopwatch sw = new Stopwatch();
sw.Reset();
sw.Start();
// MongoDb 初始化
var server = MongoDbLib.GetServerConnection(MongoDbServer);
var database = server.GetDatabase(DbName);
var tblWordList = database.GetCollection<WordItem>(Constants.TblWordList);
var tblFullText = database.GetCollection<InvertedIndex>(Constants.TblFullText);
// 針對搜尋關鍵字斷詞
List<Pair<String, Int32>> keywordTokens = _segmentor.SegWords(keyword);
// 自索引中取出對應的 word list
var buf = (from t in keywordTokens select t.First).ToList();
var query = from w in tblWordList.AsQueryable<WordItem>()
where w.Word.In(buf)
select new { w.WordId };
List<Int32> wordIdList = new List<Int32>();
foreach (var aWord in query)
{
wordIdList.Add(aWord.WordId);
}
// word id 為 0 筆，表示搜尋結果為 0
if (wordIdList.Count == 0)
{
sw.Stop();
result.SearchTime = sw.ElapsedMilliseconds / 1000.0;
return result;
}
// 自全文索引中，取出對應的記錄
var indexes = from i in tblFullText.AsQueryable<InvertedIndex>()
where i.WordId.In(wordIdList)
select i;
if (indexes.Count() != wordIdList.Count)
{
return null;
}
// 將每個 keyword token 對應回相對應的 index
List<List<IndexElement>> checkedIndex = new List<List<IndexElement>>();
foreach (var aToken in keywordTokens)
{
checkedIndex.Add(indexes.Where(t => t.Word == aToken.First).First().Indexes);
}
// 檢查各文件是否為符合的文件
var firstTokenIndex = checkedIndex[0];
Dictionary<Int32, Int32> hittedDocs = new Dictionary<Int32, Int32>();
foreach (var currentIndex in firstTokenIndex)
{
if (keywordTokens.Count == 1 || CheckDocumentIsHitted(keywordTokens, 1, checkedIndex, currentIndex))
{
if (hittedDocs.ContainsKey(currentIndex.DocId))
hittedDocs[currentIndex.DocId]++;
else
hittedDocs[currentIndex.DocId] = 1;
}
}
// 文件照分數排序，取出指定區間的 doc id 列表
var sortedDocIds = (from entry in hittedDocs orderby entry.Value descending select entry.Key).Skip(startPos).Take(fetchSize).ToList();
// 結果儲存
result.Matches = hittedDocs.Count;
sw.Stop();
result.SearchTime = sw.ElapsedMilliseconds / 1000.0;
for (int i = 0; i < fetchSize && i < sortedDocIds.Count; i++)
{
String rawText = this.GetDocumentById(sortedDocIds[i]);
result.Results.Add(new ResultItem()
{
Rank = startPos + 1 + i,
Score = hittedDocs[sortedDocIds[i]],
HitField = rawText.Replace(keyword, "<<" + keyword + ">>")
});
}
return result;
}
catch (Exception e)
{
return null;
}
}