// Starts scanning at character pos of string text for occurrence of any word
// in stemmed_terms. Returns a list of (words)*[(matched word)(words)*]+
private SnippetLine MarkTerms(ArrayList stemmed_terms, string text, ref int pos)
{
SnippetLine snippet_line = null;
int prev_match_end_pos = pos; // misnomer; means 1 + end_pos of previous word
// 1. get next word
// 2. if no next word, return arraylist
// 3. if word is not a match, following_words ++
// 4. else {
// 4a. add list to the arraylist
// 4b. add word to the arraylist
// 4c. clear list
// 4d. following_words=0
// }
// 5. if (following_words >= max_following_words) {
// 5a. add list to the arraylist
// 5b. clear list
// 5c. return list
// }
while (pos < text.Length)
{
// Find the beginning of the next token
if (IsTokenSeparator(text [pos]))
{
++pos;
continue;
}
// Find the end of the next token
int end_pos = pos + 1;
while (end_pos < text.Length && !IsTokenSeparator(text [end_pos]))
{
++end_pos;
}
string token = text.Substring(pos, end_pos - pos);
string stemmed_token = null;
bool found_match = false;
// Iterate through the stemmed terms and match the token
for (int i = 0; i < stemmed_terms.Count; i++)
{
// If this term is longer than the token in question, give up.
if (end_pos - pos < ((string)stemmed_terms [i]).Length)
{
continue;
}
// We cache the token, so as to avoid stemming it more than once
// when considering multiple terms.
if (stemmed_token == null)
{
stemmed_token = LuceneCommon.Stem(token.ToLower());
}
if (String.Compare((string)stemmed_terms [i], stemmed_token, true) != 0)
{
continue;
}
// We have a match!
found_match = true;
//Console.WriteLine ("Found match");
if (snippet_line == null)
{
snippet_line = new SnippetLine();
}
// Find the fragment before the match
int start_pos = sliding_window.StartValue;
if (start_pos == -1) // If no non-match words seen after last match
{
start_pos = prev_match_end_pos; // Use wherever previous word ended
}
sliding_window.Reset();
string before_match = text.Substring(start_pos, pos - start_pos);
snippet_line.AddNonMatchFragment(before_match);
//Console.WriteLine ("Adding [{0}, {1}]:[{2}]", start_pos, pos - 1, before_match);
snippet_line.AddMatchFragment(i, token);
//Console.WriteLine ("Adding word [{0}, {1}]:[{2}]", pos, end_pos - 1, token);
prev_match_end_pos = end_pos;
break;
}
if (!found_match)
{
// Add the start pos of the token to the window
sliding_window.Add(pos);
// If we found a match previously and saw enough following words, stop
if (snippet_line != null && snippet_line.Count > 0 && sliding_window.Count == context_length)
{
sliding_window.Reset();
string after_match = text.Substring(prev_match_end_pos, end_pos - prev_match_end_pos);
snippet_line.AddNonMatchFragment(after_match);
//Console.WriteLine ("Adding [{0}, {1}]:[{2}]", prev_match_end_pos, end_pos - 1, after_match);
return(snippet_line);
}
}
pos = end_pos;
}
// If less than 6 words came after the last match, add the rest here
if (snippet_line != null && snippet_line.Count > 0)
{
sliding_window.Reset();
string after_match = text.Substring(prev_match_end_pos, pos - prev_match_end_pos);
snippet_line.AddNonMatchFragment(after_match);
//Console.WriteLine ("Adding [{0}, {1}]:[{2}]", prev_match_end_pos, pos - 1, after_match);
//Console.WriteLine ("Sending snippet: {0}", snippet_line.ToString ());
return(snippet_line);
}
sliding_window.Reset();
return(null);
}