source: trunk/gsdl/src/colservr/phrasesearch.cpp@ 395

/**********************************************************************
 *
 * phrasesearch.cpp -- tools to search for a phrase in a larger text
 * Copyright (C) 1999  DigiLib Systems Limited
 *
 * PUT COPYRIGHT NOTICE HERE
 *
 * $Id: phrasesearch.cpp 395 1999-07-16 00:15:49Z sjboddie $
 *
 *********************************************************************/

/*
   $Log$
   Revision 1.4  1999/07/16 00:15:48  sjboddie
   changed to use termfreqclassarray type

   Revision 1.3  1999/07/07 06:19:45  rjmcnab
   Added ability to combine two or more independant queries.

   Revision 1.2  1999/07/01 09:25:54  rjmcnab
   fixed bug :-^

   Revision 1.1  1999/07/01 04:01:46  rjmcnab
   Initial revision.

 */


#include "phrasesearch.h"
#include "gsdlunicode.h"

inline unsigned char *parse_nonword_word (unsigned char *here, unsigned char *end,
                      text_t &word) {
  int c_len = 0;
  unsigned short c = 0;

  word.clear();

  // parse non word
  while (here <= end) {
    c_len = parse_utf8_char (here, end, &c);
    if (is_unicode_letdig(c)) {
      while (c_len > 0) {
    word.push_back(*here);
    here++; c_len--;
      }
      break;
    }
    here += c_len;
  }

  // parse word
  while (here <= end) {
    c_len = parse_utf8_char (here, end, &c);
    if (!is_unicode_letdig(c)) {
      here += c_len;  // it is ok to skip a nonword character
      break;
    }
    while (c_len > 0) {
      word.push_back(*here);
      here++; c_len--;
    }
  }

  return here;
}


bool doc_phrase_search (unsigned char *doc, int doclen,
            const termfreqclassarray &phrase) {
  // note: this uses the most braindead search routine :-)
  // however its not so bad as there shouldn't be many partial
  // matches

  // a null phrase matches anything
  if (phrase.empty()) return true;

  // if there is nothing then there can't be a match
  if (doc == NULL || doclen == 0) return false;
  
  text_t doc_word;
  doc_word.reserve (16);

  bool first = true;

  unsigned char *doc_here = doc;
  unsigned char *doc_herefirstword = doc;
  unsigned char *doc_end = doc+doclen-1; // unitool conventions :-/

  while (doc_here <= doc_end) {
    first = true;
    
    // there will be at least one member of phrase (see above)
    termfreqclassarray::const_iterator phrase_here = phrase.begin();
    termfreqclassarray::const_iterator phrase_end = phrase.end();
    do {
      // get the next non-word ... and ignore it, then get the next word
      doc_here = parse_nonword_word (doc_here, doc_end, doc_word);
      if (first) {doc_herefirstword = doc_here; first = false;}

      // break if this word is not the next in the phrase
      if ((*phrase_here).utf8equivterms.find (doc_word) ==
      (*phrase_here).utf8equivterms.end()) break;

      phrase_here++;
    } while (doc_here <= doc_end && phrase_here != phrase_end);

    // see if we found a phrase
    if (phrase_here == phrase_end) return true;
    
    doc_here = doc_herefirstword; // set the counter back
  }

  return false;
}


// looks for the stemmed phrase in the metadata or text associated with
// an OID. This function has not been coded with all situations in mind
bool OID_phrase_search (mgsearchclass &mgsearch,
            gdbmclass &gdbm,
            const text_t &index,
            const text_t &subcollection,
            const text_t &language,
            const text_t &longindex,
            const text_t &collection,
            const termfreqclassarray &phrase,
            int docnum) {
  // disect the long index to find out where the text should come from
  text_t level, gran;
  text_t::const_iterator longindex_here = longindex.begin();
  text_t::const_iterator longindex_end = longindex.end();
  longindex_here = getdelimitstr (longindex_here, longindex_end, ':', level);
  longindex_here = getdelimitstr (longindex_here, longindex_end, ':', gran);

  if (gran.empty()) return false;
  
  if (gran == "text") {
    char *doc = NULL;
    int doclen = 0;
  
    // get text from mg.
    if (!mgsearch.mgdocument (index, subcollection, language, collection,
                  docnum, doc, doclen)) return false;
    return doc_phrase_search ((unsigned char *)doc, doclen, phrase);
  } 

  // get OID
  char *metadata = NULL;
  text_t::size_type metadata_len = 0;
  infodbclass docnum_info;
  infodbclass OID_info;
  
  if (!gdbm.getinfo (docnum, docnum_info)) return false;
  text_t &OID = docnum_info["section"];
  if (OID.empty()) return false;
  
  // get field
  if (!gdbm.getinfo (OID, OID_info)) return false;

  metadata = (to_utf8(OID_info[gran])).getcarr(metadata_len);
  bool result = doc_phrase_search ((unsigned char *)metadata, metadata_len, phrase);
  delete [] metadata;
  
  return result;
}