SQLite

      pNew->flags |= EP_Collate;
      pExpr = pNew;
    }
  }
  return pExpr;
}
Expr *sqlite3ExprAddCollateString(Parse *pParse, Expr *pExpr, const char *zC){

  Token s;
  assert( zC!=0 );
  s.z = zC;
  s.n = sqlite3Strlen30(s.z);
  return sqlite3ExprAddCollateToken(pParse, pExpr, &s);


}

/*
** Skip over any TK_COLLATE and/or TK_AS operators at the root of
** an expression.
*/
Expr *sqlite3ExprSkipCollate(Expr *pExpr){

** COLLATE operators take first precedence.  Left operands take
** precedence over right operands.
*/
CollSeq *sqlite3ExprCollSeq(Parse *pParse, Expr *pExpr){
  sqlite3 *db = pParse->db;
  CollSeq *pColl = 0;
  Expr *p = pExpr;
  while( p ){
    int op = p->op;
    if( op==TK_CAST || op==TK_UPLUS ){
      p = p->pLeft;
      continue;
    }
    assert( op!=TK_REGISTER || p->op2!=TK_COLLATE );
    if( op==TK_COLLATE ){
      if( db->init.busy ){
        /* Do not report errors when parsing while the schema */
        pColl = sqlite3FindCollSeq(db, ENC(db), p->u.zToken, 0);
      }else{
        pColl = sqlite3GetCollSeq(pParse, ENC(db), 0, p->u.zToken);
      }
      break;

      if( j>=0 ){
        const char *zColl = p->pTab->aCol[j].zColl;
        pColl = sqlite3FindCollSeq(db, ENC(db), zColl, 0);
      }
      break;
    }
    if( p->flags & EP_Collate ){
      if( ALWAYS(p->pLeft) && (p->pLeft->flags & EP_Collate)!=0 ){
        p = p->pLeft;
      }else{
        p = p->pRight;
      }
    }else{
      break;
    }

static int evalConstExpr(Walker *pWalker, Expr *pExpr){
  Parse *pParse = pWalker->pParse;
  switch( pExpr->op ){
    case TK_IN:
    case TK_REGISTER: {
      return WRC_Prune;
    }
    case TK_COLLATE: {
      return WRC_Continue;
    }
    case TK_FUNCTION:
    case TK_AGG_FUNCTION:
    case TK_CONST_FUNC: {
      /* The arguments to a function have a fixed destination.
      ** Mark them this way to avoid generated unneeded OP_SCopy
      ** instructions. 
      */

        }
      }
      break;
    }
  }
  if( isAppropriateForFactoring(pExpr) ){
    int r1 = ++pParse->nMem;

    int r2 = sqlite3ExprCodeTarget(pParse, pExpr, r1);
    /* If r2!=r1, it means that register r1 is never used.  That is harmless
    ** but suboptimal, so we want to know about the situation to fix it.
    ** Hence the following assert: */
    assert( r2==r1 );
    pExpr->op2 = pExpr->op;
    pExpr->op = TK_REGISTER;
    pExpr->iTable = r2;
    return WRC_Prune;
  }
  return WRC_Continue;
}

    }
  }else if( pA->op!=TK_COLUMN && ALWAYS(pA->op!=TK_AGG_COLUMN) && pA->u.zToken){
    if( ExprHasProperty(pB, EP_IntValue) || NEVER(pB->u.zToken==0) ) return 2;
    if( strcmp(pA->u.zToken,pB->u.zToken)!=0 ){
      return pA->op==TK_COLLATE ? 1 : 2;
    }
  }

  return 0;
}

/*
** Compare two ExprList objects.  Return 0 if they are identical and 
** non-zero if they differ in any way.
**

      int i, j;
      KeyInfo *pKeyInfo = pOp->p4.pKeyInfo;
      assert( pKeyInfo->aSortOrder!=0 );
      sqlite3_snprintf(nTemp, zTemp, "keyinfo(%d", pKeyInfo->nField);
      i = sqlite3Strlen30(zTemp);
      for(j=0; j<pKeyInfo->nField; j++){
        CollSeq *pColl = pKeyInfo->aColl[j];
        const char *zColl = pColl ? pColl->zName : "nil";
        int n = sqlite3Strlen30(zColl);
        if( i+n>nTemp-6 ){
          memcpy(&zTemp[i],",...",4);
          break;
        }
        zTemp[i++] = ',';
        if( pKeyInfo->aSortOrder[j] ){
          zTemp[i++] = '-';
        }
        memcpy(&zTemp[i], zColl, n+1);
        i += n;




      }
      zTemp[i++] = ')';
      zTemp[i] = 0;
      assert( i<nTemp );
      break;
    }
    case P4_COLLSEQ: {

          assert(pX->pLeft);
          pColl = sqlite3BinaryCompareCollSeq(pParse, pX->pLeft, pX->pRight);
          if( pColl==0 ) pColl = pParse->db->pDfltColl;
  
          for(j=0; pIdx->aiColumn[j]!=iColumn; j++){
            if( NEVER(j>=pIdx->nColumn) ) return 0;
          }
          if( sqlite3StrICmp(pColl->zName, pIdx->azColl[j]) ) continue;
        }
        return pTerm;
      }
    }
  }
  return 0;
}