dbf64ebe4a5118f6ce418f0beb42fbd20821113a
chmalee
  Fri Oct 28 17:15:59 2022 -0700
Fix erroneous trix prefixing problem. When looking for snippets we use a larger trixPrefixSize for a speedup, but I was forgetting to reset the size when opening up the next trix index later on. Fix missing highlights on search results page. refs #26963

diff --git src/lib/trix.c src/lib/trix.c
index e02810e..83cbe95 100644
--- src/lib/trix.c
+++ src/lib/trix.c
@@ -1,960 +1,966 @@
 /* trix - text retrieval index.  Stuff for fast two level index
  * of text for fast word searches. */
 
 /* Copyright (C) 2013 The Regents of the University of California 
  * See kent/LICENSE or http://genome.ucsc.edu/license/ for licensing information. */
 
 #include "common.h"
 #include "hash.h"
 #include "linefile.h"
 #include "trix.h"
 #include "sqlNum.h"
 #include "udc.h"
 #include "net.h"
 #include "rangeTree.h"
 #include "portable.h"
 
 /* Some local structures for the search. */
 struct trixHitPos 
 /* A hit to the index. */
     {
     struct trixHitPos *next;	/* Next in list */
     char *itemId;		/* Associated itemId */
     int wordIx;			/* Which word this is part of. */
     int leftoverLetters;	/* Number of letters at end of word not matched */
     };
 
 struct trixWordResult
 /* Results of a search on one word. */
     {
     struct trixWordResult *next;
     char *word;			/* Word name. */
     struct trixHitPos *hitList;	/* Hit list.  May be shared (not allocated here). */
     struct trixHitPos *hit;	/* Current position while iterating through hit list. */
     struct trixHitPos *iHit;	/* Current position during an inner iteration. */
     };
 
 int trixPrefixSize = 5;
 /* Some cleanup code. */
 
 static void trixHitPosFree(struct trixHitPos **pPos)
 /* Free up trixHitPos. */
 {
 struct trixHitPos *pos = *pPos;
 if (pos != NULL)
     {
     freeMem(pos->itemId);
     freez(pPos);
     }
 }
 
 static void trixHitPosFreeList(struct trixHitPos **pList)
 /* Free up a list of trixHitPoss. */
 {
 struct trixHitPos *el, *next;
 for (el = *pList; el != NULL; el = next)
     {
     next = el->next;
     trixHitPosFree(&el);
     }
 *pList = NULL;
 }
 
 static void trixWordResultFree(struct trixWordResult **pTwr)
 /* Free up a trixWordResult */
 {
 struct trixWordResult *twr = *pTwr;
 if (twr != NULL)
     {
     freeMem(twr->word);
     freez(pTwr);
     }
 }
 
 static void trixWordResultFreeList(struct trixWordResult **pList)
 /* Free up a list of trixWordResults. */
 {
 struct trixWordResult *el, *next;
 for (el = *pList; el != NULL; el = next)
     {
     next = el->next;
     trixWordResultFree(&el);
     }
 *pList = NULL;
 }
 
 static void freeHitCallback(void *val)
 /* Val is actually list trixHitPos.  This called to free stuff in hash. */
 {
 struct trixHitPos *posList = val;
 trixHitPosFreeList(&posList);
 }
 
 void trixClose(struct trix **pTrix)
 /* Close up index and free up associated resources. */
 {
 struct trix *trix = *pTrix;
 if (trix != NULL)
     {
     freeMem(trix->ixx);
     hashTraverseVals(trix->wordHitHash, freeHitCallback);
     hashFree(&trix->wordHitHash);	/* Need to free items? */
     freez(pTrix);
     }
 }
 
 void trixSearchResultFree(struct trixSearchResult **pTsr)
 /* Free up data associated with trixSearchResult. */
 {
 struct trixSearchResult *tsr = *pTsr;
 if (tsr != NULL)
     {
     freeMem(tsr->itemId);
     freez(pTsr);
     }
 }
 
 void trixSearchResultFreeList(struct trixSearchResult **pList)
 /* Free up a list of trixSearchResults. */
 {
 struct trixSearchResult *el, *next;
 for (el = *pList; el != NULL; el = next)
     {
     next = el->next;
     trixSearchResultFree(&el);
     }
 *pList = NULL;
 }
 
 
 /* Code that makes, rather than cleans up. */
 
 static char unhexTable[128];	/* Lookup table to help with hex conversion. */
 
 static void initUnhexTable()
 /* Initialize a table for fast unhexing of numbers. */
 {
 unhexTable['0'] = 0;
 unhexTable['1'] = 1;
 unhexTable['2'] = 2;
 unhexTable['3'] = 3;
 unhexTable['4'] = 4;
 unhexTable['5'] = 5;
 unhexTable['6'] = 6;
 unhexTable['7'] = 7;
 unhexTable['8'] = 8;
 unhexTable['9'] = 9;
 unhexTable['A'] = 10;
 unhexTable['B'] = 11;
 unhexTable['C'] = 12;
 unhexTable['D'] = 13;
 unhexTable['E'] = 14;
 unhexTable['F'] = 15;
 }
 
 static off_t unhex(char hex[10])
 /* Convert 10 character hex string to off_t */
 {
 off_t  x = 0;
 int i;
 
 for (i=0; i<10; ++i)
    {
    x <<= 4;
    x += unhexTable[(unsigned)hex[i]];
    }
 return x;
 }
 
 struct trix *trixNew()
 /* Create a new empty trix index. */
 {
 struct trix *trix;
 AllocVar(trix);
 trix->ixxAlloc = 8*1024;
 AllocArray(trix->ixx, trix->ixxAlloc);
 trix->wordHitHash = newHash(8);
 return trix;
 }
 
 void trixAddToIxx(struct trix *trix, off_t pos, char *prefix)
 /* Add to trix->ixx. */
 {
 struct trixIxx *ixx;
 if (trix->ixxSize >= trix->ixxAlloc)
      {
      trix->ixxAlloc += trix->ixxAlloc;	/* Double allocation. */
      ExpandArray(trix->ixx, trix->ixxSize, trix->ixxAlloc);
      }
 ixx = trix->ixx + trix->ixxSize;
 ixx->pos = pos;
 AllocVar(ixx->prefix);
 memcpy(ixx->prefix, prefix, trixPrefixSize);
 trix->ixxSize += 1;
 }
 
 // wrappers around the udc or lineFile routines
 static void *ourOpen(struct trix *trix, char *fileName)
 {
 if (trix->useUdc)
     return (void *)udcFileOpen(fileName, NULL);
 return (void *)lineFileOpen(fileName, TRUE);
 }
 
 static boolean ourReadLine(struct trix *trix, void *lf, char **line)
 {
 if (trix->useUdc)
     {
     *line = udcReadLine((struct udcFile *)lf);
     return *line != NULL;
     }
 return lineFileNext((struct lineFile *)lf, line, NULL);
 }
 
 static void ourClose(struct trix *trix, void **lf)
 {
 if (trix->useUdc)
     udcFileClose((struct udcFile **)lf);
 else
     lineFileClose((struct lineFile **)lf);
 }
 
 void ourSeek(struct trix *trix, struct lineFile *lf, off_t ixPos)
 {
 if (trix->useUdc)
     udcSeek((struct udcFile *)lf, ixPos);
 else
     lineFileSeek((struct lineFile *)lf, ixPos, SEEK_SET);
 }
 
 struct trix *trixOpen(char *ixFile)
 /* Open up index.  Load second level index in memory. */
 {
 struct trix *trix = trixNew();
 trix->useUdc = FALSE;
 if (hasProtocol(ixFile))
     trix->useUdc = TRUE;
 
 char ixxFile[PATH_LEN];
 void *lf;
 char *line;
 
 initUnhexTable();
 safef(ixxFile, sizeof(ixxFile), "%sx", ixFile);
 lf = ourOpen(trix, ixxFile);
 while (ourReadLine(trix, lf, &line) )
     {
     off_t pos = unhex(line+trixPrefixSize);
     trixAddToIxx(trix, pos, line);
     }
 ourClose(trix, &lf);
 trix->lf = ourOpen(trix, ixFile);
 return trix;
 }
 
 void trixCopyToPrefix(char *word, char *prefix)
 /* Copy first part of word to prefix.  If need be end pad with spaces. */
 {
 int len = strlen(word);
 if (len >= trixPrefixSize)
     memcpy(prefix, word, trixPrefixSize);
 else
     {
     memset(prefix, ' ', trixPrefixSize);
     memcpy(prefix, word, len);
     }
 }
 
 static off_t trixFindIndexStartLine(struct trixIxx *trixIxx, int ixxSize, char *word)
 /* Find start position of line we want to start at in the first level
  * index. */
 {
 char wordPrefix[trixPrefixSize];
 int i;
 off_t pos = 0;
 
 trixCopyToPrefix(word, wordPrefix);
 toLowerN(wordPrefix, trixPrefixSize);
 for (i=0; i < ixxSize; ++i)
     {
     struct trixIxx *ixx = trixIxx + i;
     if (memcmp(wordPrefix, ixx->prefix, trixPrefixSize) < 0)
        break;
     pos = ixx->pos;
     }
 return pos;
 }
 
 static struct trixHitPos *trixParseHitList(char *hitWord, char *hitString,
 	int leftoverLetters)
 /* Parse out hit string, inserting zeroes in it during process.
  * Return result as list of trixHitPos. */
 {
 struct trixHitPos *hit, *hitList = NULL;
 char *word;
 while ((word = nextWord(&hitString)) != NULL)
     {
     char *parts[3];
     int partCount;
     partCount = chopByChar(word, ',', parts, ArraySize(parts));
     if (partCount != 2)
         errAbort("Error in index format at word %s", hitWord);
     AllocVar(hit);
     hit->itemId = cloneString(parts[0]);
     hit->wordIx = sqlUnsigned(parts[1]);
     hit->leftoverLetters = leftoverLetters;
     slAddHead(&hitList, hit);
     }
 slReverse(&hitList);
 return hitList;
 }
 
 int trixHitPosCmp(const void *a, const void *b)
 /* Compare function to sort trixHitPos. */
 {
 struct trixHitPos *aHitPos = *((struct trixHitPos **)a);
 struct trixHitPos *bHitPos = *((struct trixHitPos **)b);
 int diff = strcmp(aHitPos->itemId, bHitPos->itemId);
 if (diff == 0)
     {
     diff = aHitPos->wordIx - bHitPos->wordIx;
     if (diff == 0)
         diff = aHitPos->leftoverLetters - bHitPos->leftoverLetters;
     }
 return diff;
 }
 
 static int reasonablePrefix(char *prefix, char *word, enum trixSearchMode mode)
 /* Return non-negative if prefix is reasonable for word.
  * Returns number of letters left in word not matched by
  * prefix. */
 {
 int prefixLen = strlen(prefix);
 int wordLen = strlen(word);
 int suffixLen = wordLen - prefixLen;
 if (suffixLen == 0)
    return 0;
 else if ((mode == tsmExpand && prefixLen >= 3) ||
          (mode == tsmFirstFive && prefixLen >= 5))
     {
     int wordEnd;
     char *suffix = word + prefixLen;
     boolean prefixEndsInDigit = isdigit(word[prefixLen-1]);
     /* Find a word marker - either end of string, '-', '.', or '_'
      * or a number. */
     for (wordEnd=0; wordEnd < suffixLen; ++wordEnd)
         {
 	char c = suffix[wordEnd];
 	if (c == '-' || c == '.' || c == '_' || (!prefixEndsInDigit && isdigit(c)))
 	    break;
 	}
     if (wordEnd <= 2)
        return wordEnd;
     if (wordEnd == 3 && startsWith("ing", suffix))
        return wordEnd;
     if (mode == tsmFirstFive && prefixLen >= 5)
         return wordEnd;
     }
 return -1;
 }
 
 
 struct trixWordResult *trixSearchWordResults(struct trix *trix, 
 	char *searchWord, enum trixSearchMode mode)
 /* Get results for single word from index.  Returns NULL if no matches. */
 {
 char *line, *word;
 struct trixWordResult *twr = NULL;
 struct trixHitPos *hitList = hashFindVal(trix->wordHitHash, searchWord);
 
 if (hitList == NULL)
     {
     struct trixHitPos *oneHitList;
     off_t ixPos = trixFindIndexStartLine(trix->ixx, trix->ixxSize, searchWord);
     ourSeek(trix, trix->lf, ixPos);
     while (ourReadLine(trix, trix->lf, &line))
         {
         word = nextWord(&line);
         if (startsWith(searchWord, word))
             {
             int leftoverLetters = reasonablePrefix(searchWord, word, mode);
             /* uglyf("reasonablePrefix(%s,%s)=%d<BR>\n", searchWord, word, leftoverLetters); */
             if (leftoverLetters >= 0)
                 {
                 oneHitList = trixParseHitList(searchWord, line, leftoverLetters);
                 hitList = slCat(oneHitList, hitList);
                 }
             }
         else if (strcmp(searchWord, word) < 0)
             break;
         }
     slSort(&hitList, trixHitPosCmp);
     hashAdd(trix->wordHitHash, searchWord, hitList);
     }
 if (hitList != NULL)
     {
     AllocVar(twr);
     twr->word = cloneString(searchWord);
     twr->hitList = hitList;
     }
 return twr;
 }
 
 
 #ifdef DEBUG
 void trwDump(struct trixWordResult *twr)
 /* Dump out one trixWordResult to stdout. */
 {
 struct trixHitPos *hit;
 int hitIx, maxHits = 8;
 
 printf("%d matches to %s:", slCount(twr->hitList), twr->word);
 for (hit=twr->hitList, hitIx=0; hit != NULL && hitIx < maxHits; hit=hit->next, hitIx+=1)
     printf(" %s@%d", hit->itemId, hit->wordIx);
 if (hit != NULL)
     printf(" ...");
 printf("<BR>\n");
 }
 #endif /* DEBUG */
 
 static char *highestId(struct trixWordResult *twrList)
 /* Return highest itemId at current twr->hit */
 {
 char *itemId = twrList->hit->itemId;
 struct trixWordResult *twr;
 
 for (twr = twrList->next; twr != NULL; twr = twr->next)
     {
     if (strcmp(itemId, twr->hit->itemId) < 0)
         itemId = twr->hit->itemId;
     }
 return itemId;
 }
 
 static boolean seekOneToId(struct trixWordResult *twr, char *itemId)
 /* Move twr->hit forward until it hits itemId.  Return FALSE if
  * moved past where itemId would be without hitting it. */
 {
 struct trixHitPos *hit;
 int diff = -1;
 for (hit = twr->hit; hit != NULL; hit = hit->next)
     {
     diff = strcmp(itemId, hit->itemId);
     if (diff <= 0)
         break;
     }
 twr->hit = hit;
 return diff == 0;
 }
 
 static boolean seekAllToId(struct trixWordResult *twrList, char *itemId)
 /* Try to seek all twr's in list to the same itemId */
 {
 struct trixWordResult *twr;
 boolean allHit = TRUE;
 for (twr = twrList; twr != NULL; twr = twr->next)
     {
     if (!seekOneToId(twr, itemId))
         allHit = FALSE;
     }
 return allHit;
 }
 
 static void seekAllPastId(struct trixWordResult *twrList, char *itemId)
 /* Try to seek all twr's in list to past the itemId. */
 {
 struct trixWordResult *twr;
 for (twr = twrList; twr != NULL; twr = twr->next)
     {
     struct trixHitPos *hit;
     for (hit = twr->hit; hit != NULL; hit = hit->next)
 	if (!sameString(hit->itemId, itemId))
 	    break;
     twr->hit = hit;
     }
 }
 
 static boolean anyTwrDone(struct trixWordResult *twrList)
 /* Return TRUE if any of the items in list are done */
 {
 struct trixWordResult *twr;
 for (twr = twrList; twr != NULL; twr = twr->next)
     if (twr->hit == NULL)
         return TRUE;
 return FALSE;
 }
 
 static int findUnorderedSpan(struct trixWordResult *twrList,
 	char *itemId, int *retLeftoverLetters, int **retWordPos)
 /* Find out smallest number of words in doc that will cover
  * all words in search. */
 {
 int minSpan = BIGNUM;
 int leftoverLetters = 0;
 int curLeftover = 0;
 int minPossibleSpan;
 int i;
 struct trixWordResult *twr;
 
 /* Set up iHit pointers we use to keep track of our 
  * search.  Don't want to mess with hit pointers as they
  * will be used later. */
 for (twr = twrList; twr != NULL; twr = twr->next)
     twr->iHit = twr->hit;
 int numWords = minPossibleSpan = slCount(twrList);
 int *unorderedWordPositions;
 AllocArray(unorderedWordPositions, numWords);
 for (;;)
     {
     int minWord = BIGNUM, maxWord=0, span;
 
     /* Figure out current span and save as min if it's smallest so far. */
     for (twr = twrList, i = 0; twr != NULL && i < numWords; twr = twr->next, i++)
         {
         unorderedWordPositions[i] = twr->iHit->wordIx-1;
         int curWord = twr->iHit->wordIx;
         if (curWord < minWord)
             minWord = curWord;
         if (curWord > maxWord)
             maxWord = curWord;
         curLeftover += twr->iHit->leftoverLetters;
         }
     span = maxWord - minWord;
     if (span < minSpan)
         {
         minSpan = span;
         leftoverLetters = curLeftover;
         }
 
     /* Advance iHit past minWord.  Break if we go outside of our doc or item. */
     for (twr = twrList; twr != NULL; twr = twr->next)
         {
         if (twr->iHit->wordIx == minWord)
             {
             struct trixHitPos *hit = twr->iHit = twr->iHit->next;
             if (hit == NULL || !sameString(hit->itemId, itemId) || minSpan == minPossibleSpan)
                 {
                 *retLeftoverLetters = leftoverLetters;
                 *retWordPos = unorderedWordPositions;
                 return span + 1;
                 }
             }
         }
     }
 *retWordPos = unorderedWordPositions;
 } 
 
 int findWordPos(struct trixWordResult *twrList, char *itemId)
 /* Figure out the first word position.  For multiple words, this
  * will be the maximimum first word position of all words. 
  * This assumes that the hits are sorted by word position
  * within a document. NOTE: this does not take into account
  * that the span may not actually start at that word */
 {
 int firstWordPos = 0;
 struct trixWordResult *twr;
 for (twr = twrList; twr != NULL; twr = twr->next)
     {
     int pos = twr->hit->wordIx;
     if (firstWordPos < pos)
         firstWordPos = pos;
     }
 return firstWordPos;
 }
 
 static int findOrderedSpan(struct trixWordResult *twrList, char *itemId, int **retWordPos)
 /* Find out smallest number of words in doc that will cover
  * all words in search. */
 {
 int minSpan = BIGNUM - 1;  // subtract 1 to accomodate adding 1 below
 struct trixWordResult *twr;
 
 /* Set up iHit pointers we use to keep track of our 
  * search.  Don't want to mess with hit pointers as they
  * will be used later. */
 for (twr = twrList; twr != NULL; twr = twr->next)
     twr->iHit = twr->hit;
 
 int numWords = slCount(twrList);
 int *orderedWordPositions;
 AllocArray(orderedWordPositions, numWords);
 for (;;)
     {
     int startWord = twrList->iHit->wordIx-1;
     int endWord = startWord;
     int span, i;
     struct trixHitPos *hit;
     // we haven't found a span yet so initialize to the first word start position
     if (minSpan == BIGNUM - 1)
         orderedWordPositions[0] = startWord;
 
     /* Set up twr->iHit to be closest one past hit of previous twr. */
     for (twr = twrList->next, i = 1; twr != NULL && i < numWords; twr = twr->next, i++)
         {
         for (hit = twr->iHit; ; hit = hit->next)
             {
             if (hit == NULL || !sameString(hit->itemId, itemId))
                 return minSpan + 1;
             if (hit->wordIx > endWord)
                 break;
             }
         twr->iHit = hit;
         endWord = hit->wordIx;
         orderedWordPositions[i] = hit->wordIx-1;
         }
     span = endWord - startWord;
     if (span < minSpan)
         {
         orderedWordPositions[0] = startWord;
         CopyArray(orderedWordPositions, *retWordPos, numWords);
         minSpan = span;
         }
 
     /* Advance to next occurence of first word. */
     hit = twrList->iHit = twrList->iHit->next;
     if (hit == NULL || !sameString(hit->itemId, itemId))
         {
         return minSpan+1;
         }
     }
 }
 
 
 static struct trixSearchResult *findMultipleWordHits(struct trixWordResult *twrList)
 /* Return list of items that are hit by all words. */
 {
 struct trixWordResult *twr;
 struct trixSearchResult *tsList = NULL, *ts;
 
 /* Initially set hit position to start on all words. */
 for (twr = twrList; twr != NULL; twr = twr->next)
     twr->hit = twr->hitList;
 
 for (;;)
     {
     char *itemId = highestId(twrList);
     if (seekAllToId(twrList, itemId))
         {
         AllocVar(ts);
         ts->itemId = cloneString(itemId);
         // NOTE: tsr->wordPos first gets filled in by findUnorderedSpan.
         // If findOrderedSpan also finds the search words in order, tsr->wordPos
         // becomes that order instead of the unordered positions. Ideally I suppose
         // it would be best that there were two word position arrays saved for each
         // type
         ts->unorderedSpan = findUnorderedSpan(twrList, itemId, &ts->leftoverLetters, &ts->wordPos);
         ts->orderedSpan = findOrderedSpan(twrList, itemId, &ts->wordPos);
         ts->wordPosSize = slCount(twrList);
         slAddHead(&tsList, ts);
         }
     seekAllPastId(twrList, itemId);
     if (anyTwrDone(twrList))
         break;
     }
 slReverse(&tsList);
 return tsList;
 }
 
 int trixSearchResultCmp(const void *va, const void *vb)
 /* Compare two trixSearchResult in such a way that most relevant searches tend to be first. */
 {
 const struct trixSearchResult *a = *((struct trixSearchResult **)va);
 const struct trixSearchResult *b = *((struct trixSearchResult **)vb);
 int dif;
 dif = a->unorderedSpan - b->unorderedSpan;
 if (dif == 0)
     {
     dif = a->orderedSpan - b->orderedSpan;
     if (dif == 0)
         {
         dif = a->leftoverLetters - b->leftoverLetters;
         if (dif == 0)
             {
             int i;
             for (i = 0; i < a->wordPosSize; i++)
                 {
                 dif = a->wordPos[i] - b->wordPos[i];
                 if (dif != 0)
                     break;
                 }
             }
         }
     }
 return dif;
 }
 
 struct trixSearchResult *trixSearch(struct trix *trix, int wordCount, char **words,
                                     enum trixSearchMode mode)
 /* Return a list of items that match all words.  This will be sorted so that
  * multiple-word matches where the words are closer to each other and in the
  * right order will be first.  Single word matches will be prioritized so that those
  * closer to the start of the search text will appear before those later.
  * Do a trixSearchResultFreeList when done.  If mode is tsmExpand or tsmFirstFive then
  * this will match not only the input words, but also additional words that start with
  * the input words. If addSnippets is true, go back to the original text and include
  * the text around the matching word as a "word1 word2 ... matchedWord word3 word4 ..."
  * style snippet. The snippet will have '...' in between multi-word matches if the
  * span between matched words is 'too' long. */
 {
 struct trixWordResult *twr, *twrList = NULL;
 struct trixSearchResult *ts, *tsList = NULL;
 int wordIx;
 boolean gotMiss = FALSE;
 
 if (wordCount == 1)
     {
     struct trixHitPos *hit;
     char *lastId = "";
     twr = twrList = trixSearchWordResults(trix, words[0], mode);
     if (twr == NULL)
         return NULL;
     for (hit = twr->hitList; hit != NULL; hit = hit->next)
         {
         if (!sameString(lastId, hit->itemId))
             {
             lastId = hit->itemId;
             AllocVar(ts);
             ts->itemId = hit->itemId;        /* Transfer itemId */
             hit->itemId = NULL;
             ts->orderedSpan = 1;
             ts->unorderedSpan = 1;
             AllocArray(ts->wordPos, 1);
             ts->wordPos[0] = hit->wordIx - 1;
             ts->wordPosSize = 1;
             ts->leftoverLetters = hit->leftoverLetters;
             slAddHead(&tsList, ts);
             }
         }
     }
 else
     {
     for (wordIx=0; wordIx<wordCount; ++wordIx)
         {
         char *searchWord = words[wordIx];
         twr = trixSearchWordResults(trix, searchWord, mode);
         if (twr == NULL)
             {
             gotMiss = TRUE;
             break;
             }
         slAddHead(&twrList, twr);
 #ifdef DEBUG
         trwDump(twr);
 #endif /* DEBUG */
         }
     if (!gotMiss)
         {
         slReverse(&twrList);
         tsList = findMultipleWordHits(twrList);
         }
     }
 trixWordResultFreeList(&twrList);
 slSort(&tsList, trixSearchResultCmp);
 return tsList;
 }
 
 void snippetIndexAddToIxx(struct snippetIndex *snippetIndex, off_t pos, char *prefix)
 /* Add to trix->ixx. */
 {
 struct trixIxx *ixx;
 if (snippetIndex->ixxSize >= snippetIndex->ixxAlloc)
      {
      snippetIndex->ixxAlloc += snippetIndex->ixxAlloc;	/* Double allocation. */
      ExpandArray(snippetIndex->ixx, snippetIndex->ixxSize, snippetIndex->ixxAlloc);
      }
 ixx = snippetIndex->ixx + snippetIndex->ixxSize;
 ixx->pos = pos;
 AllocVar(ixx->prefix);
 toLowerN(prefix, trixPrefixSize);
 memcpy(ixx->prefix, prefix, trixPrefixSize);
 snippetIndex->ixxSize += 1;
 }
 
 static void openSnippetIxx(struct snippetIndex *snippetIndex, char *ixxFile, struct trix *trix)
 {
 int prefixSize = 15;
 snippetIndex->ixxAlloc = 8*1024;
 AllocArray(snippetIndex->ixx, snippetIndex->ixxAlloc);
 void *lf = ourOpen(trix, ixxFile);
 char *line;
 while (ourReadLine(trix, lf, &line) )
     {
     off_t pos = unhex(line+prefixSize);
     snippetIndexAddToIxx(snippetIndex, pos, line);
     }
 ourClose(trix, &lf);
 }
 
 static void openSnippetIndex(struct trix *trix)
 /* Fill out a struct snippetIndex on a trix index */
 {
 char *baseName = cloneString(trix->lf->fileName);
 chopSuffix(baseName);
 char origFile[PATH_LEN];
 safef(origFile, sizeof(origFile), "%s.txt", baseName);
 if (!fileExists(origFile))
     safef(origFile, sizeof(origFile), "%s.tab", baseName);
 if (!fileExists(origFile))
     errAbort("Can't find original file used for indexing, base name: '%s', %s.txt or %s.tab should exist",
             baseName, baseName, baseName);
 char offsetFile[PATH_LEN];
 char ixxFile[PATH_LEN];
 safef(offsetFile, sizeof(origFile), "%s.offsets", baseName);
 if (!fileExists(offsetFile))
     errAbort("Can't find offset file '%s.offsets'", baseName);
 safef(ixxFile, sizeof(origFile), "%s.offsets.ixx", baseName);
 if (!fileExists(ixxFile))
     errAbort("Can't find offsets.ixx file '%s.offsets.ixx'", baseName);
 struct snippetIndex *snippetIndex = NULL;
 AllocVar(snippetIndex);
 snippetIndex->origFile = lineFileOpen(origFile, TRUE);
 snippetIndex->textIndex = lineFileOpen(offsetFile, TRUE);
 openSnippetIxx(snippetIndex, ixxFile, trix);
 trix->snippetIndex = snippetIndex;
 }
 
 bool wordMiddleChars[256];  /* Characters that may be part of a word. */
 bool wordBeginChars[256];
 
 void initCharTables()
 /* Initialize tables that describe characters. */
 {
 int c;
 for (c=0; c<256; ++c)
     if (isalnum(c))
        wordBeginChars[c] = wordMiddleChars[c] = TRUE;
 wordBeginChars['_'] = wordMiddleChars['_'] = TRUE;
 wordMiddleChars['.'] = TRUE;
 wordMiddleChars['-'] = TRUE;
 }
 
 char *skipToWord(char *s)
 /* Skip to next word character.  Return NULL at end of string. */
 {
 unsigned char c;
 while ((c = *s) != 0)
     {
     if (wordBeginChars[c])
         return s;
     s += 1;
     }
 return NULL;
 }
 
 char *skipOutWord(char *start)
 /* Skip to next non-word character.  Returns empty string at end. */
 {
 char *s = start;
 unsigned char c;
 while ((c = *s) != 0)
     {
     if (!wordMiddleChars[c])
         break;
     s += 1;
     }
 while (s > start && !wordBeginChars[(int)(s[-1])])
     s -= 1;
 return s;
 }
 
 static struct rbTree *wordPosToRangeTree(int *intList, int len)
 /* Convert an array of integers to a range tree with 10 context around each int */
 {
 struct rbTree *rt = rangeTreeNew();
 int i;
 for (i = 0; i < len; i++)
     {
     int temp = intList[i] - 10;
     if (temp < 0) temp = 0;
     rangeTreeAdd(rt, temp, intList[i]+10);
     }
 return rt;
 }
 
 void addSnippetForResult(struct trixSearchResult *tsr, struct trix *trix)
 /* Find the snippet for a search result */
 {
 struct snippetIndex *snippetIndex = trix->snippetIndex;
 char *ourDocId = tsr->itemId;
 static struct dyString *snippet = NULL;
 if (snippet == NULL)
     snippet = dyStringNew(0);
 else
     dyStringClear(snippet);
 off_t origFileOffset = 0, offsetFilePos = trixFindIndexStartLine(snippetIndex->ixx, snippetIndex->ixxSize, ourDocId);
 ourSeek(trix, snippetIndex->textIndex, offsetFilePos);
 char *snippetIxLine, *origTextLine;
 char *thisDocId;
 while (ourReadLine(trix, snippetIndex->textIndex, &snippetIxLine))
     {
     thisDocId = nextWord(&snippetIxLine);
     if (sameString(thisDocId, ourDocId))
         {
         origFileOffset = sqlUnsignedLong(nextWord(&snippetIxLine));
         ourSeek(trix, snippetIndex->origFile, origFileOffset);
         ourReadLine(trix, snippetIndex->origFile, &origTextLine);
         nextWord(&origTextLine);
         char *origText = skipLeadingSpaces(origTextLine);
         // make a rangeTree out of wordPos
         intSort(tsr->wordPosSize, tsr->wordPos);
         struct rbTree *rt = wordPosToRangeTree(tsr->wordPos, tsr->wordPosSize);
         int i, end = tsr->wordPos[tsr->wordPosSize-1] + 10;
         char word[128];
         char *s, *e = origText;
         boolean didEllipse = FALSE;
         for (i = 0 ; i < end; i++)
             {
             s = skipToWord(e);
             if (s == NULL)
                 break;
             e = skipOutWord(s);
             if (rangeTreeOverlaps(rt, i, i+1))
                 {
                 int len = e - s;
                 safencpy(word, sizeof(word), s, len);
                 if (isNotEmpty(word))
                     {
                     int j;
                     boolean bold = FALSE;
                     for (j = 0; j < tsr->wordPosSize; j++)
                         if (i == tsr->wordPos[j])
                             bold = TRUE;
                     if (bold)
                         dyStringPrintf(snippet, "<b>%s</b>", word);
                     else
                         dyStringPrintf(snippet, "%s", word);
                     if (i < end)
                         dyStringPrintf(snippet, " ");
                     didEllipse = FALSE;
                     }
                 else
                     break;
                 }
             else if (!didEllipse)
                 {
                 didEllipse = TRUE;
                 dyStringPrintf(snippet, " ... ");
                 }
             }
         tsr->snippet = dyStringCannibalize(&snippet);
         break;
         }
     }
 }
 
+void resetPrefixSize()
+{
+trixPrefixSize = 5;
+}
+
 void initSnippetIndex(struct trix *trix)
 /* Setup what we need to obtain snippets */
 {
 trixPrefixSize = 15;
 initCharTables();
 openSnippetIndex(trix);
 }
 
 void addSnippetsToSearchResults(struct trixSearchResult *tsrList, struct trix *trix)
 /* Add snippets to each search result in tsrList */
 {
 initSnippetIndex(trix);
 struct trixSearchResult *tsr;
 for (tsr = tsrList; tsr != NULL; tsr = tsr->next)
     addSnippetForResult(tsr, trix);
+resetPrefixSize();
 }