SQLite

*/
typedef struct Fts5Expr Fts5Expr;
typedef struct Fts5ExprNode Fts5ExprNode;
typedef struct Fts5Parse Fts5Parse;
typedef struct Fts5Token Fts5Token;
typedef struct Fts5ExprPhrase Fts5ExprPhrase;
typedef struct Fts5ExprNearset Fts5ExprNearset;
typedef struct Fts5ExprColset Fts5ExprColset;

struct Fts5Token {
  const char *p;                  /* Token text (not NULL terminated) */
  int n;                          /* Size of buffer p in bytes */
};

/* Parse a MATCH expression. */

);

Fts5ExprNearset *sqlite3Fts5ParseNearset(
  Fts5Parse*, 
  Fts5ExprNearset*,
  Fts5ExprPhrase* 
);

Fts5ExprColset *sqlite3Fts5ParseColset(
  Fts5Parse*, 
  Fts5ExprColset*, 
  Fts5Token *
);

void sqlite3Fts5ParsePhraseFree(Fts5ExprPhrase*);
void sqlite3Fts5ParseNearsetFree(Fts5ExprNearset*);
void sqlite3Fts5ParseNodeFree(Fts5ExprNode*);

void sqlite3Fts5ParseSetDistance(Fts5Parse*, Fts5ExprNearset*, Fts5Token*);
void sqlite3Fts5ParseSetColset(Fts5Parse*, Fts5ExprNearset*, Fts5ExprColset*);
void sqlite3Fts5ParseFinished(Fts5Parse *pParse, Fts5ExprNode *p);
void sqlite3Fts5ParseNear(Fts5Parse *pParse, Fts5Token*);

/*
** End of interface to code in fts5_expr.c.
**************************************************************************/

struct Fts5ExprPhrase {
  Fts5ExprNode *pNode;            /* FTS5_STRING node this phrase is part of */
  Fts5Buffer poslist;             /* Current position list */
  int nTerm;                      /* Number of entries in aTerm[] */
  Fts5ExprTerm aTerm[0];          /* Terms that make up this phrase */
};

/*
** If a NEAR() clump may only match a specific set of columns, then
** Fts5ExprNearset.pColset points to an object of the following type.
** Each entry in the aiCol[] array
*/
struct Fts5ExprColset {
  int nCol;
  int aiCol[1];
};

/*
** One or more phrases that must appear within a certain token distance of
** each other within each matching document.
*/
struct Fts5ExprNearset {
  int nNear;                      /* NEAR parameter */
  Fts5ExprColset *pColset;        /* Columns to search (NULL -> all columns) */
  int nPhrase;                    /* Number of entries in aPhrase[] array */
  Fts5ExprPhrase *apPhrase[0];    /* Array of phrase pointers */
};


/*
** Parse context.

  while( fts5ExprIsspace(*z) ) z++;

  pToken->p = z;
  pToken->n = 1;
  switch( *z ){
    case '(':  tok = FTS5_LP;    break;
    case ')':  tok = FTS5_RP;    break;
    case '[':  tok = FTS5_LSP;   break;
    case ']':  tok = FTS5_RSP;   break;
    case ':':  tok = FTS5_COLON; break;
    case ',':  tok = FTS5_COMMA; break;
    case '+':  tok = FTS5_PLUS;  break;
    case '*':  tok = FTS5_STAR;  break;
    case '\0': tok = FTS5_EOF;   break;

    case '"': {

      pNew->nPhrase = 1;
      pNew->apExprPhrase = apPhrase;
      pNew->apExprPhrase[0] = pCopy;

      pNode->eType = FTS5_STRING;
      pNode->pNear = pNear;


      pNear->nPhrase = 1;
      pNear->apPhrase[0] = pCopy;

      pCopy->nTerm = pOrig->nTerm;
      pCopy->pNode = pNode;
    }else{
      /* At least one allocation failed. Free them all. */

**
** SQLITE_OK is returned if an error occurs, or an SQLite error code 
** otherwise. It is not considered an error code if the current rowid is 
** not a match.
*/
static int fts5ExprPhraseIsMatch(
  Fts5Expr *pExpr,                /* Expression pPhrase belongs to */
  Fts5ExprColset *pColset,        /* Restrict matches to these columns */
  Fts5ExprPhrase *pPhrase,        /* Phrase object to initialize */
  int *pbMatch                    /* OUT: Set to true if really a match */
){
  Fts5PoslistWriter writer = {0};
  Fts5PoslistReader aStatic[4];
  Fts5PoslistReader *aIter = aStatic;
  int i;
  int rc = SQLITE_OK;
  int iCol = pColset ? pColset->aiCol[0] : -1;

  fts5BufferZero(&pPhrase->poslist);

  /* If the aStatic[] array is not large enough, allocate a large array
  ** using sqlite3_malloc(). This approach could be improved upon. */
  if( pPhrase->nTerm>(sizeof(aStatic) / sizeof(aStatic[0])) ){
    int nByte = sizeof(Fts5PoslistReader) * pPhrase->nTerm;

** contain any entries for column iCol, return 0.
*/
static int fts5ExprExtractCol(
  const u8 **pa,                  /* IN/OUT: Pointer to poslist */
  int n,                          /* IN: Size of poslist in bytes */
  int iCol                        /* Column to extract from poslist */
){

  int iCurrent = 0;
  const u8 *p = *pa;
  const u8 *pEnd = &p[n];         /* One byte past end of position list */
  u8 prev = 0;

  while( iCol!=iCurrent ){
    /* Advance pointer p until it points to pEnd or an 0x01 byte that is

  Fts5Expr *pExpr,                /* Expression that pNear is a part of */
  Fts5ExprNode *pNode             /* The "NEAR" node (FTS5_STRING) */
){
  Fts5ExprNearset *pNear = pNode->pNear;
  int rc = SQLITE_OK;

  while( 1 ){


    if( pNear->nPhrase==1 && pNear->apPhrase[0]->nTerm==1 ){
      /* If this "NEAR" object is actually a single phrase that consists 
      ** of a single term only, then grab pointers into the poslist
      ** managed by the fts5_index.c iterator object. This is much faster 
      ** than synthesizing a new poslist the way we have to for more
      ** complicated phrase or NEAR expressions.  */
      Fts5ExprPhrase *pPhrase = pNear->apPhrase[0];
      Fts5IndexIter *pIter = pPhrase->aTerm[0].pIter;
      Fts5ExprColset *pColset = pNear->pColset;
      const u8 *pPos;
      int nPos;

      rc = sqlite3Fts5IterPoslist(pIter, &pPos, &nPos, &pNode->iRowid);



      /* If the term may match any column, then this must be a match. 
      ** Return immediately in this case. Otherwise, try to find the
      ** part of the poslist that corresponds to the required column.
      ** If it can be found, return. If it cannot, the next iteration
      ** of the loop will test the next rowid in the database for this
      ** term.  */
      if( pColset==0 ){
        assert( pPhrase->poslist.nSpace==0 );
        pPhrase->poslist.p = (u8*)pPos;
        pPhrase->poslist.n = nPos;
      }else if( pColset->nCol==1 ){
        assert( pPhrase->poslist.nSpace==0 );
        pPhrase->poslist.n = fts5ExprExtractCol(&pPos, nPos, pColset->aiCol[0]);
        pPhrase->poslist.p = (u8*)pPos;
      }else{
        int i;
        fts5BufferZero(&pPhrase->poslist);
        for(i=0; i<pColset->nCol; i++){
          const u8 *pSub = pPos;
          int nSub = fts5ExprExtractCol(&pSub, nPos, pColset->aiCol[i]);
          if( nSub ){
            fts5BufferAppendBlob(&rc, &pPhrase->poslist, nSub, pSub);
          }
        }
      }

      if( pPhrase->poslist.n ) return rc;
    }else{
      int i;

      assert( pNear->pColset==0 || pNear->pColset->nCol==1 );

      /* Advance the iterators until they all point to the same rowid */
      rc = fts5ExprNearNextRowidMatch(pExpr, pNode);
      if( rc!=SQLITE_OK || pNode->bEof ) break;

      /* Check that each phrase in the nearset matches the current row.
      ** Populate the pPhrase->poslist buffers at the same time. If any
      ** phrase is not a match, break out of the loop early.  */
      for(i=0; rc==SQLITE_OK && i<pNear->nPhrase; i++){
        Fts5ExprPhrase *pPhrase = pNear->apPhrase[i];
        if( pPhrase->nTerm>1 || pNear->pColset ){
          int bMatch = 0;
          rc = fts5ExprPhraseIsMatch(pExpr, pNear->pColset, pPhrase, &bMatch);
          if( bMatch==0 ) break;
        }else{
          rc = sqlite3Fts5IterPoslistBuffer(
              pPhrase->aTerm[0].pIter, &pPhrase->poslist
              );
        }
      }

    if( pNear==0 ){
      int nByte = sizeof(Fts5ExprNearset) + SZALLOC * sizeof(Fts5ExprPhrase*);
      pRet = sqlite3_malloc(nByte);
      if( pRet==0 ){
        pParse->rc = SQLITE_NOMEM;
      }else{
        memset(pRet, 0, nByte);

      }
    }else if( (pNear->nPhrase % SZALLOC)==0 ){
      int nNew = pNear->nPhrase + SZALLOC;
      int nByte = sizeof(Fts5ExprNearset) + nNew * sizeof(Fts5ExprPhrase*);

      pRet = (Fts5ExprNearset*)sqlite3_realloc(pNear, nByte);
      if( pRet==0 ){

*/
void sqlite3Fts5ParseNearsetFree(Fts5ExprNearset *pNear){
  if( pNear ){
    int i;
    for(i=0; i<pNear->nPhrase; i++){
      fts5ExprPhraseFree(pNear->apPhrase[i]);
    }
    sqlite3_free(pNear->pColset);
    sqlite3_free(pNear);
  }
}

void sqlite3Fts5ParseFinished(Fts5Parse *pParse, Fts5ExprNode *p){
  assert( pParse->pExpr==0 );
  pParse->pExpr = p;

    }
  }else{
    nNear = FTS5_DEFAULT_NEARDIST;
  }
  pNear->nNear = nNear;
}

/*
** The second argument passed to this function may be NULL, or it may be
** an existing Fts5ExprColset object. This function returns a pointer to
** a new colset object containing the contents of (p) with new value column
** number iCol appended. 
**
** If an OOM error occurs, store an error code in pParse and return NULL.
** The old colset object (if any) is not freed in this case.
*/
static Fts5ExprColset *fts5ParseColset(
  Fts5Parse *pParse,              /* Store SQLITE_NOMEM here if required */
  Fts5ExprColset *p,              /* Existing colset object */
  int iCol                        /* New column to add to colset object */
){
  int nCol = p ? p->nCol : 0;     /* Num. columns already in colset object */
  Fts5ExprColset *pNew;           /* New colset object to return */

  assert( pParse->rc==SQLITE_OK );
  assert( iCol>=0 && iCol<pParse->pConfig->nCol );

  pNew = sqlite3_realloc(p, sizeof(Fts5ExprColset) + sizeof(int)*nCol);
  if( pNew==0 ){
    pParse->rc = SQLITE_NOMEM;
  }else{
    int *aiCol = pNew->aiCol;
    int i, j;
    for(i=0; i<nCol; i++){
      if( aiCol[i]==iCol ) return pNew;
      if( aiCol[i]>iCol ) break;
    }
    for(j=nCol; j>i; j--){
      aiCol[j] = aiCol[j-1];
    }
    aiCol[i] = iCol;
    pNew->nCol = nCol+1;

#ifndef NDEBUG
    /* Check that the array is in order and contains no duplicate entries. */
    for(i=1; i<pNew->nCol; i++) assert( pNew->aiCol[i]>pNew->aiCol[i-1] );
#endif
  }

  return pNew;
}

Fts5ExprColset *sqlite3Fts5ParseColset(
  Fts5Parse *pParse,              /* Store SQLITE_NOMEM here if required */
  Fts5ExprColset *pColset,        /* Existing colset object */
  Fts5Token *p
){
  Fts5ExprColset *pRet = 0;

  if( pParse->rc==SQLITE_OK ){
    int iCol;
    char *z = 0;
    int rc = fts5ParseStringFromToken(p, &z);
    if( rc==SQLITE_OK ){
      Fts5Config *pConfig = pParse->pConfig;
      sqlite3Fts5Dequote(z);
      for(iCol=0; iCol<pConfig->nCol; iCol++){
        if( 0==sqlite3_stricmp(pConfig->azCol[iCol], z) ){

          break;
        }
      }
      if( iCol==pConfig->nCol ){
        sqlite3Fts5ParseError(pParse, "no such column: %s", z);
      }
      sqlite3_free(z);
    }else{
      pParse->rc = rc;
    }

    if( pParse->rc==SQLITE_OK ){
      pRet = fts5ParseColset(pParse, pColset, iCol);
    }
  }

  if( pParse->rc!=SQLITE_OK ){
    assert( pRet==0 );
    sqlite3_free(pColset);
  }

  return pRet;
}

void sqlite3Fts5ParseSetColset(
  Fts5Parse *pParse, 
  Fts5ExprNearset *pNear, 
  Fts5ExprColset *pColset 
){
  if( pNear ){
    pNear->pColset = pColset;
  }else{
    sqlite3_free(pColset);
  }
}

/*
** Allocate and return a new expression object. If anything goes wrong (i.e.
** OOM error), leave an error code in pParse and return NULL.
*/

  if( pExpr->eType==FTS5_STRING ){
    Fts5ExprNearset *pNear = pExpr->pNear;
    int i; 
    int iTerm;

    zRet = fts5PrintfAppend(zRet, "[%s ", zNearsetCmd);
    if( zRet==0 ) return 0;
    if( pNear->pColset ){
      int *aiCol = pNear->pColset->aiCol;
      int nCol = pNear->pColset->nCol;
      if( nCol==1 ){
        zRet = fts5PrintfAppend(zRet, "-col %d ", aiCol[0]);
      }else{
        zRet = fts5PrintfAppend(zRet, "-col {%d", aiCol[0]);
        for(i=1; i<pNear->pColset->nCol; i++){
          zRet = fts5PrintfAppend(zRet, " %d", aiCol[i]);
        }
        zRet = fts5PrintfAppend(zRet, "} ");
      }
      if( zRet==0 ) return 0;
    }

    if( pNear->nPhrase>1 ){
      zRet = fts5PrintfAppend(zRet, "-near %d ", pNear->nNear);
      if( zRet==0 ) return 0;
    }

static char *fts5ExprPrint(Fts5Config *pConfig, Fts5ExprNode *pExpr){
  char *zRet = 0;
  if( pExpr->eType==FTS5_STRING ){
    Fts5ExprNearset *pNear = pExpr->pNear;
    int i; 
    int iTerm;

    if( pNear->pColset ){
      int iCol = pNear->pColset->aiCol[0];
      zRet = fts5PrintfAppend(zRet, "%s : ", pConfig->azCol[iCol]);
      if( zRet==0 ) return 0;
    }

    if( pNear->nPhrase>1 ){
      zRet = fts5PrintfAppend(zRet, "NEAR(");
      if( zRet==0 ) return 0;
    }

}

/*
** Move to the next matching rowid. 
*/
int sqlite3Fts5IterNext(Fts5IndexIter *pIter){
  assert( pIter->pIndex->rc==SQLITE_OK );

  fts5MultiIterNext(pIter->pIndex, pIter->pMulti, 0, 0);
  return fts5IndexReturn(pIter->pIndex);
}

/*
** Move to the next matching term/rowid. Used by the fts5vocab module.
*/
int sqlite3Fts5IterNextScan(Fts5IndexIter *pIter){
  Fts5Index *p = pIter->pIndex;
  Fts5MultiSegIter *pMulti = pIter->pMulti;

  assert( pIter->pIndex->rc==SQLITE_OK );
  assert( pMulti );


  fts5MultiIterNext(p, pMulti, 0, 0);
  if( p->rc==SQLITE_OK ){
    Fts5SegIter *pSeg = &pMulti->aSeg[ pMulti->aFirst[1].iFirst ];
    if( pSeg->pLeaf && pSeg->term.p[0]!=FTS5_MAIN_PREFIX ){
      fts5DataRelease(pSeg->pLeaf);
      pSeg->pLeaf = 0;
    }

exprlist(A) ::= exprlist(X) cnearset(Y). {
  A = sqlite3Fts5ParseNode(pParse, FTS5_AND, X, Y, 0);
}

cnearset(A) ::= nearset(X). { 
  A = sqlite3Fts5ParseNode(pParse, FTS5_STRING, 0, 0, X); 
}
cnearset(A) ::= colset(X) COLON nearset(Y). { 
  sqlite3Fts5ParseSetColset(pParse, Y, X);
  A = sqlite3Fts5ParseNode(pParse, FTS5_STRING, 0, 0, Y); 
}

%type colset {Fts5ExprColset*}
%destructor colset { sqlite3_free($$); }
%type colsetlist {Fts5ExprColset*}
%destructor colsetlist { sqlite3_free($$); }

colset(A) ::= LSP colsetlist(X) RSP. { A = X; }
colset(A) ::= STRING(X). {
  A = sqlite3Fts5ParseColset(pParse, 0, &X);
}

colsetlist(A) ::= colsetlist(Y) STRING(X). { 
  A = sqlite3Fts5ParseColset(pParse, Y, &X); }
colsetlist(A) ::= STRING(X). { 
  A = sqlite3Fts5ParseColset(pParse, 0, &X); 
}


%type nearset     {Fts5ExprNearset*}
%type nearphrases {Fts5ExprNearset*}
%destructor nearset { sqlite3Fts5ParseNearsetFree($$); }
%destructor nearphrases { sqlite3Fts5ParseNearsetFree($$); }

nearset(A) ::= phrase(X). { A = sqlite3Fts5ParseNearset(pParse, 0, X); }

    95  {h b n j t k i h o q u}             {w n g i t o k c a m y p f l x c p}
    96  {f c x p y r b m o l m o a}         {p c a q s u n n x d c f a o}
    97  {u h h k m n k}                     {u b v n u a o c}
    98  {s p e t c z d f n w f}             {l s f j b l c e s h}
    99  {r c v w i v h a t a c v c r e}     {h h u m g o f b a e o}
}

#-------------------------------------------------------------------------
# Usage:
#
#   poslist aCol ?-pc VARNAME? ?-near N? ?-col C? -- phrase1 phrase2...
#
# This command is used to test if a document (set of column values) matches
# the logical equivalent of a single FTS5 NEAR() clump and, if so, return
# the equivalent of an FTS5 position list.
#
# Parameter $aCol is passed a list of the column values for the document
# to test. Parameters $phrase1 and so on are the phrases.
#
# The result is a list of phrase hits. Each phrase hit is formatted as
# three integers separated by "." characters, in the following format:
#
#   <phrase number> . <column number> . <token offset>
#
# Options:
#
#   -near N        (NEAR distance. Default 10)
#   -col  C        (List of column indexes to match against)
#   -pc   VARNAME  (variable in caller frame to use for phrase numbering)
#
proc poslist {aCol args} {
  set O(-near) 10
  set O(-col)  {}
  set O(-pc)   ""

  set nOpt [lsearch -exact $args --]
  if {$nOpt<0} { error "no -- option" }

  foreach {k v} [lrange $args 0 [expr $nOpt-1]] {
    if {[info exists O($k)]==0} { error "unrecognized option $k" }

      set A($j,$i) [list]
    }
  }

  set iCol -1
  foreach col $aCol {
    incr iCol

    if {$O(-col)!="" && [lsearch $O(-col) $iCol]<0} continue
    set nToken [llength $col]

    set iFL [expr $O(-near) >= $nToken ? $nToken - 1 : $O(-near)]
    for { } {$iFL < $nToken} {incr iFL} {
      for {set iPhrase 0} {$iPhrase<$nPhrase} {incr iPhrase} {
        set B($iPhrase) [list]
      }

    } $res
  }

  #-------------------------------------------------------------------------
  # Queries on a specific column.
  #
  foreach {tn expr} {
    1.1 "x:a"
    1.2 "y:a"
    1.3 "x:b"
    1.4 "y:b"
    2.1 "[x]:a"
    2.2 "[y]:a"
    2.3 "[x]:b"
    2.4 "[y]:b"

    3.1 "[x y]:a"
    3.2 "[y x]:a"
    3.3 "[x x]:b"
    3.4 "[y y]:b"

    4.1 {["x" "y"]:a}
    4.2 {["y" x]:a}
    4.3 {[x "x"]:b}
    4.4 {["y" y]:b}
  } {
    set res [matchdata 1 $expr]
    do_execsql_test $tn2.3.$tn.[llength $res] { 
      SELECT rowid, fts5_test_poslist(xx) FROM xx WHERE xx match $expr
    } $res
  }