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Overview
Comment:Experimental change that allows overloaded functions to be analyzed by the xBestIndex method and used by the xFilter method of a virtual table.
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SHA3-256:a353b1d7ee6c5989ba1b98a3990c9a4c2ff39ae66572fd1200606e8ef585e5fa
User & Date: drh 2018-05-26 18:03:48
Context
2018-05-26
20:04
Merge the ability to plan virtual table queries using overloaded functions. check-in: 2c2a202c user: drh tags: rtree-geopoly
18:03
Experimental change that allows overloaded functions to be analyzed by the xBestIndex method and used by the xFilter method of a virtual table. Leaf check-in: a353b1d7 user: drh tags: vtab-func-constraint
16:00
Store application-defined function names as lower-case to avoid the need for case conversions before calling xFindFunction on virtual tables. Avoid using lookaside to store the destructors for application defined functions, as lookaside should be reserved for transient allocations. check-in: 777189ce user: drh tags: trunk
Changes
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Changes to src/expr.c.

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      ** see if it is a column in a virtual table.  This is done because
      ** the left operand of infix functions (the operand we want to
      ** control overloading) ends up as the second argument to the
      ** function.  The expression "A glob B" is equivalent to 
      ** "glob(B,A).  We want to use the A in "A glob B" to test
      ** for function overloading.  But we use the B term in "glob(B,A)".
      */
      if( nFarg>=2 && (pExpr->flags & EP_InfixFunc) ){
        pDef = sqlite3VtabOverloadFunction(db, pDef, nFarg, pFarg->a[1].pExpr);
      }else if( nFarg>0 ){
        pDef = sqlite3VtabOverloadFunction(db, pDef, nFarg, pFarg->a[0].pExpr);
      }
#endif
      if( pDef->funcFlags & SQLITE_FUNC_NEEDCOLL ){
        if( !pColl ) pColl = db->pDfltColl; 







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      ** see if it is a column in a virtual table.  This is done because
      ** the left operand of infix functions (the operand we want to
      ** control overloading) ends up as the second argument to the
      ** function.  The expression "A glob B" is equivalent to 
      ** "glob(B,A).  We want to use the A in "A glob B" to test
      ** for function overloading.  But we use the B term in "glob(B,A)".
      */
      if( nFarg>=2 && ExprHasProperty(pExpr, EP_InfixFunc) ){
        pDef = sqlite3VtabOverloadFunction(db, pDef, nFarg, pFarg->a[1].pExpr);
      }else if( nFarg>0 ){
        pDef = sqlite3VtabOverloadFunction(db, pDef, nFarg, pFarg->a[0].pExpr);
      }
#endif
      if( pDef->funcFlags & SQLITE_FUNC_NEEDCOLL ){
        if( !pColl ) pColl = db->pDfltColl; 

Changes to src/sqlite.h.in.

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#define SQLITE_INDEX_CONSTRAINT_GLOB      66
#define SQLITE_INDEX_CONSTRAINT_REGEXP    67
#define SQLITE_INDEX_CONSTRAINT_NE        68
#define SQLITE_INDEX_CONSTRAINT_ISNOT     69
#define SQLITE_INDEX_CONSTRAINT_ISNOTNULL 70
#define SQLITE_INDEX_CONSTRAINT_ISNULL    71
#define SQLITE_INDEX_CONSTRAINT_IS        72


/*
** CAPI3REF: Register A Virtual Table Implementation
** METHOD: sqlite3
**
** ^These routines are used to register a new [virtual table module] name.
** ^Module names must be registered before







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#define SQLITE_INDEX_CONSTRAINT_GLOB      66
#define SQLITE_INDEX_CONSTRAINT_REGEXP    67
#define SQLITE_INDEX_CONSTRAINT_NE        68
#define SQLITE_INDEX_CONSTRAINT_ISNOT     69
#define SQLITE_INDEX_CONSTRAINT_ISNOTNULL 70
#define SQLITE_INDEX_CONSTRAINT_ISNULL    71
#define SQLITE_INDEX_CONSTRAINT_IS        72
#define SQLITE_INDEX_CONSTRAINT_FUNCTION 150

/*
** CAPI3REF: Register A Virtual Table Implementation
** METHOD: sqlite3
**
** ^These routines are used to register a new [virtual table module] name.
** ^Module names must be registered before

Changes to src/whereexpr.c.

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** appropriate virtual table operator.  The return value is 1 or 2 if there
** is a match.  The usual return is 1, but if the RHS is also a column
** of virtual table in forms (5) or (7) then return 2.
**
** If the expression matches none of the patterns above, return 0.
*/
static int isAuxiliaryVtabOperator(

  Expr *pExpr,                    /* Test this expression */
  unsigned char *peOp2,           /* OUT: 0 for MATCH, or else an op2 value */
  Expr **ppLeft,                  /* Column expression to left of MATCH/op2 */
  Expr **ppRight                  /* Expression to left of MATCH/op2 */
){
  if( pExpr->op==TK_FUNCTION ){
    static const struct Op2 {
................................................................................
    Expr *pCol;                     /* Column reference */
    int i;

    pList = pExpr->x.pList;
    if( pList==0 || pList->nExpr!=2 ){
      return 0;
    }








    pCol = pList->a[1].pExpr;
    if( pCol->op!=TK_COLUMN || !IsVirtual(pCol->pTab) ){
      return 0;
    }
    for(i=0; i<ArraySize(aOp); i++){
      if( sqlite3StrICmp(pExpr->u.zToken, aOp[i].zOp)==0 ){
        *peOp2 = aOp[i].eOp2;
        *ppRight = pList->a[0].pExpr;
        *ppLeft = pCol;
        return 1;
































      }
    }
  }else if( pExpr->op==TK_NE || pExpr->op==TK_ISNOT || pExpr->op==TK_NOTNULL ){
    int res = 0;
    Expr *pLeft = pExpr->pLeft;
    Expr *pRight = pExpr->pRight;
    if( pLeft->op==TK_COLUMN && IsVirtual(pLeft->pTab) ){
................................................................................
  ** is one of MATCH, LIKE, GLOB, REGEXP, !=, IS, IS NOT, or NOT NULL.
  ** This information is used by the xBestIndex methods of
  ** virtual tables.  The native query optimizer does not attempt
  ** to do anything with MATCH functions.
  */
  if( pWC->op==TK_AND ){
    Expr *pRight = 0, *pLeft = 0;
    int res = isAuxiliaryVtabOperator(pExpr, &eOp2, &pLeft, &pRight);
    while( res-- > 0 ){
      int idxNew;
      WhereTerm *pNewTerm;
      Bitmask prereqColumn, prereqExpr;

      prereqExpr = sqlite3WhereExprUsage(pMaskSet, pRight);
      prereqColumn = sqlite3WhereExprUsage(pMaskSet, pLeft);







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** appropriate virtual table operator.  The return value is 1 or 2 if there
** is a match.  The usual return is 1, but if the RHS is also a column
** of virtual table in forms (5) or (7) then return 2.
**
** If the expression matches none of the patterns above, return 0.
*/
static int isAuxiliaryVtabOperator(
  sqlite3 *db,                    /* Parsing context */
  Expr *pExpr,                    /* Test this expression */
  unsigned char *peOp2,           /* OUT: 0 for MATCH, or else an op2 value */
  Expr **ppLeft,                  /* Column expression to left of MATCH/op2 */
  Expr **ppRight                  /* Expression to left of MATCH/op2 */
){
  if( pExpr->op==TK_FUNCTION ){
    static const struct Op2 {
................................................................................
    Expr *pCol;                     /* Column reference */
    int i;

    pList = pExpr->x.pList;
    if( pList==0 || pList->nExpr!=2 ){
      return 0;
    }

    /* Built-in operators MATCH, GLOB, LIKE, and REGEXP attach to a
    ** virtual table on their second argument, which is the same as
    ** the left-hand side operand in their in-fix form.
    **
    **       vtab_column MATCH expression
    **       MATCH(expression,vtab_column)
    */
    pCol = pList->a[1].pExpr;
    if( pCol->op==TK_COLUMN && IsVirtual(pCol->pTab) ){


      for(i=0; i<ArraySize(aOp); i++){
        if( sqlite3StrICmp(pExpr->u.zToken, aOp[i].zOp)==0 ){
          *peOp2 = aOp[i].eOp2;
          *ppRight = pList->a[0].pExpr;
          *ppLeft = pCol;
          return 1;
        }
      }
    }

    /* We can also match against the first column of overloaded
    ** functions where xFindFunction returns a value of at least
    ** SQLITE_INDEX_CONSTRAINT_FUNCTION.
    **
    **      OVERLOADED(vtab_column,expression)
    **
    ** Historically, xFindFunction expected to see lower-case function
    ** names.  But for this use case, xFindFunction is expected to deal
    ** with function names in an arbitrary case.
    */
    pCol = pList->a[0].pExpr;
    if( pCol->op==TK_COLUMN && IsVirtual(pCol->pTab) ){
      sqlite3_vtab *pVtab;
      sqlite3_module *pMod;
      void (*xNotUsed)(sqlite3_context*,int,sqlite3_value**);
      void *pNotUsed;
      pVtab = sqlite3GetVTable(db, pCol->pTab)->pVtab;
      assert( pVtab!=0 );
      assert( pVtab->pModule!=0 );
      pMod = (sqlite3_module *)pVtab->pModule;
      if( pMod->xFindFunction!=0 ){
        i = pMod->xFindFunction(pVtab,2, pExpr->u.zToken, &xNotUsed, &pNotUsed);
        if( i>=SQLITE_INDEX_CONSTRAINT_FUNCTION ){
          *peOp2 = i;
          *ppRight = pList->a[1].pExpr;
          *ppLeft = pCol;
          return 1;
        }
      }
    }
  }else if( pExpr->op==TK_NE || pExpr->op==TK_ISNOT || pExpr->op==TK_NOTNULL ){
    int res = 0;
    Expr *pLeft = pExpr->pLeft;
    Expr *pRight = pExpr->pRight;
    if( pLeft->op==TK_COLUMN && IsVirtual(pLeft->pTab) ){
................................................................................
  ** is one of MATCH, LIKE, GLOB, REGEXP, !=, IS, IS NOT, or NOT NULL.
  ** This information is used by the xBestIndex methods of
  ** virtual tables.  The native query optimizer does not attempt
  ** to do anything with MATCH functions.
  */
  if( pWC->op==TK_AND ){
    Expr *pRight = 0, *pLeft = 0;
    int res = isAuxiliaryVtabOperator(db, pExpr, &eOp2, &pLeft, &pRight);
    while( res-- > 0 ){
      int idxNew;
      WhereTerm *pNewTerm;
      Bitmask prereqColumn, prereqExpr;

      prereqExpr = sqlite3WhereExprUsage(pMaskSet, pRight);
      prereqColumn = sqlite3WhereExprUsage(pMaskSet, pLeft);