sourcemod-central: extensions/sqlite/sqlite-source/expr.c@b7aa2b626807

     1 /*

     2 ** 2001 September 15

     3 **

     4 ** The author disclaims copyright to this source code.  In place of

     5 ** a legal notice, here is a blessing:

     6 **

     7 **    May you do good and not evil.

     8 **    May you find forgiveness for yourself and forgive others.

     9 **    May you share freely, never taking more than you give.

    10 **

    11 *************************************************************************

    12 ** This file contains routines used for analyzing expressions and

    13 ** for generating VDBE code that evaluates expressions in SQLite.

    14 **

    15 ** $Id$

    16 */

    17 #include "sqliteInt.h"

    18 #include <ctype.h>

    20 /*

    21 ** Return the 'affinity' of the expression pExpr if any.

    22 **

    23 ** If pExpr is a column, a reference to a column via an 'AS' alias,

    24 ** or a sub-select with a column as the return value, then the

    25 ** affinity of that column is returned. Otherwise, 0x00 is returned,

    26 ** indicating no affinity for the expression.

    27 **

    28 ** i.e. the WHERE clause expresssions in the following statements all

    29 ** have an affinity:

    30 **

    31 ** CREATE TABLE t1(a);

    32 ** SELECT * FROM t1 WHERE a;

    33 ** SELECT a AS b FROM t1 WHERE b;

    34 ** SELECT * FROM t1 WHERE (select a from t1);

    35 */

    36 char sqlite3ExprAffinity(Expr *pExpr){

    37   int op = pExpr->op;

    38   if( op==TK_SELECT ){

    39     return sqlite3ExprAffinity(pExpr->pSelect->pEList->a[0].pExpr);

    40   }

    41 #ifndef SQLITE_OMIT_CAST

    42   if( op==TK_CAST ){

    43     return sqlite3AffinityType(&pExpr->token);

    44   }

    45 #endif

    46   return pExpr->affinity;

    47 }

    49 /*

    50 ** Set the collating sequence for expression pExpr to be the collating

    51 ** sequence named by pToken.   Return a pointer to the revised expression.

    52 ** The collating sequence is marked as "explicit" using the EP_ExpCollate

    53 ** flag.  An explicit collating sequence will override implicit

    54 ** collating sequences.

    55 */

    56 Expr *sqlite3ExprSetColl(Parse *pParse, Expr *pExpr, Token *pName){

    57   CollSeq *pColl;

    58   if( pExpr==0 ) return 0;

    59   pColl = sqlite3LocateCollSeq(pParse, (char*)pName->z, pName->n);

    60   if( pColl ){

    61     pExpr->pColl = pColl;

    62     pExpr->flags |= EP_ExpCollate;

    63   }

    64   return pExpr;

    65 }

    67 /*

    68 ** Return the default collation sequence for the expression pExpr. If

    69 ** there is no default collation type, return 0.

    70 */

    71 CollSeq *sqlite3ExprCollSeq(Parse *pParse, Expr *pExpr){

    72   CollSeq *pColl = 0;

    73   if( pExpr ){

    74     int op;

    75     pColl = pExpr->pColl;

    76     op = pExpr->op;

    77     if( (op==TK_CAST || op==TK_UPLUS) && !pColl ){

    78       return sqlite3ExprCollSeq(pParse, pExpr->pLeft);

    79     }

    80   }

    81   if( sqlite3CheckCollSeq(pParse, pColl) ){

    82     pColl = 0;

    83   }

    84   return pColl;

    85 }

    87 /*

    88 ** pExpr is an operand of a comparison operator.  aff2 is the

    89 ** type affinity of the other operand.  This routine returns the

    90 ** type affinity that should be used for the comparison operator.

    91 */

    92 char sqlite3CompareAffinity(Expr *pExpr, char aff2){

    93   char aff1 = sqlite3ExprAffinity(pExpr);

    94   if( aff1 && aff2 ){

    95     /* Both sides of the comparison are columns. If one has numeric

    96     ** affinity, use that. Otherwise use no affinity.

    97     */

    98     if( sqlite3IsNumericAffinity(aff1) || sqlite3IsNumericAffinity(aff2) ){

    99       return SQLITE_AFF_NUMERIC;

   100     }else{

   101       return SQLITE_AFF_NONE;

   102     }

   103   }else if( !aff1 && !aff2 ){

   104     /* Neither side of the comparison is a column.  Compare the

   105     ** results directly.

   106     */

   107     return SQLITE_AFF_NONE;

   108   }else{

   109     /* One side is a column, the other is not. Use the columns affinity. */

   110     assert( aff1==0 || aff2==0 );

   111     return (aff1 + aff2);

   112   }

   113 }

   115 /*

   116 ** pExpr is a comparison operator.  Return the type affinity that should

   117 ** be applied to both operands prior to doing the comparison.

   118 */

   119 static char comparisonAffinity(Expr *pExpr){

   120   char aff;

   121   assert( pExpr->op==TK_EQ || pExpr->op==TK_IN || pExpr->op==TK_LT ||

   122           pExpr->op==TK_GT || pExpr->op==TK_GE || pExpr->op==TK_LE ||

   123           pExpr->op==TK_NE );

   124   assert( pExpr->pLeft );

   125   aff = sqlite3ExprAffinity(pExpr->pLeft);

   126   if( pExpr->pRight ){

   127     aff = sqlite3CompareAffinity(pExpr->pRight, aff);

   128   }

   129   else if( pExpr->pSelect ){

   130     aff = sqlite3CompareAffinity(pExpr->pSelect->pEList->a[0].pExpr, aff);

   131   }

   132   else if( !aff ){

   133     aff = SQLITE_AFF_NONE;

   134   }

   135   return aff;

   136 }

   138 /*

   139 ** pExpr is a comparison expression, eg. '=', '<', IN(...) etc.

   140 ** idx_affinity is the affinity of an indexed column. Return true

   141 ** if the index with affinity idx_affinity may be used to implement

   142 ** the comparison in pExpr.

   143 */

   144 int sqlite3IndexAffinityOk(Expr *pExpr, char idx_affinity){

   145   char aff = comparisonAffinity(pExpr);

   146   switch( aff ){

   147     case SQLITE_AFF_NONE:

   148       return 1;

   149     case SQLITE_AFF_TEXT:

   150       return idx_affinity==SQLITE_AFF_TEXT;

   151     default:

   152       return sqlite3IsNumericAffinity(idx_affinity);

   153   }

   154 }

   156 /*

   157 ** Return the P1 value that should be used for a binary comparison

   158 ** opcode (OP_Eq, OP_Ge etc.) used to compare pExpr1 and pExpr2.

   159 ** If jumpIfNull is true, then set the low byte of the returned

   160 ** P1 value to tell the opcode to jump if either expression

   161 ** evaluates to NULL.

   162 */

   163 static int binaryCompareP1(Expr *pExpr1, Expr *pExpr2, int jumpIfNull){

   164   char aff = sqlite3ExprAffinity(pExpr2);

   165   return ((int)sqlite3CompareAffinity(pExpr1, aff))+(jumpIfNull?0x100:0);

   166 }

   168 /*

   169 ** Return a pointer to the collation sequence that should be used by

   170 ** a binary comparison operator comparing pLeft and pRight.

   171 **

   172 ** If the left hand expression has a collating sequence type, then it is

   173 ** used. Otherwise the collation sequence for the right hand expression

   174 ** is used, or the default (BINARY) if neither expression has a collating

   175 ** type.

   176 **

   177 ** Argument pRight (but not pLeft) may be a null pointer. In this case,

   178 ** it is not considered.

   179 */

   180 CollSeq *sqlite3BinaryCompareCollSeq(

   181   Parse *pParse,

   182   Expr *pLeft,

   183   Expr *pRight

   184 ){

   185   CollSeq *pColl;

   186   assert( pLeft );

   187   if( pLeft->flags & EP_ExpCollate ){

   188     assert( pLeft->pColl );

   189     pColl = pLeft->pColl;

   190   }else if( pRight && pRight->flags & EP_ExpCollate ){

   191     assert( pRight->pColl );

   192     pColl = pRight->pColl;

   193   }else{

   194     pColl = sqlite3ExprCollSeq(pParse, pLeft);

   195     if( !pColl ){

   196       pColl = sqlite3ExprCollSeq(pParse, pRight);

   197     }

   198   }

   199   return pColl;

   200 }

   202 /*

   203 ** Generate code for a comparison operator.

   204 */

   205 static int codeCompare(

   206   Parse *pParse,    /* The parsing (and code generating) context */

   207   Expr *pLeft,      /* The left operand */

   208   Expr *pRight,     /* The right operand */

   209   int opcode,       /* The comparison opcode */

   210   int dest,         /* Jump here if true.  */

   211   int jumpIfNull    /* If true, jump if either operand is NULL */

   212 ){

   213   int p1 = binaryCompareP1(pLeft, pRight, jumpIfNull);

   214   CollSeq *p3 = sqlite3BinaryCompareCollSeq(pParse, pLeft, pRight);

   215   return sqlite3VdbeOp3(pParse->pVdbe, opcode, p1, dest, (void*)p3, P3_COLLSEQ);

   216 }

   218 /*

   219 ** Construct a new expression node and return a pointer to it.  Memory

   220 ** for this node is obtained from sqlite3_malloc().  The calling function

   221 ** is responsible for making sure the node eventually gets freed.

   222 */

   223 Expr *sqlite3Expr(

   224   sqlite3 *db,            /* Handle for sqlite3DbMallocZero() (may be null) */

   225   int op,                 /* Expression opcode */

   226   Expr *pLeft,            /* Left operand */

   227   Expr *pRight,           /* Right operand */

   228   const Token *pToken     /* Argument token */

   229 ){

   230   Expr *pNew;

   231   pNew = sqlite3DbMallocZero(db, sizeof(Expr));

   232   if( pNew==0 ){

   233     /* When malloc fails, delete pLeft and pRight. Expressions passed to

   234     ** this function must always be allocated with sqlite3Expr() for this

   235     ** reason.

   236     */

   237     sqlite3ExprDelete(pLeft);

   238     sqlite3ExprDelete(pRight);

   239     return 0;

   240   }

   241   pNew->op = op;

   242   pNew->pLeft = pLeft;

   243   pNew->pRight = pRight;

   244   pNew->iAgg = -1;

   245   if( pToken ){

   246     assert( pToken->dyn==0 );

   247     pNew->span = pNew->token = *pToken;

   248   }else if( pLeft ){

   249     if( pRight ){

   250       sqlite3ExprSpan(pNew, &pLeft->span, &pRight->span);

   251       if( pRight->flags & EP_ExpCollate ){

   252         pNew->flags |= EP_ExpCollate;

   253         pNew->pColl = pRight->pColl;

   254       }

   255     }

   256     if( pLeft->flags & EP_ExpCollate ){

   257       pNew->flags |= EP_ExpCollate;

   258       pNew->pColl = pLeft->pColl;

   259     }

   260   }

   262   sqlite3ExprSetHeight(pNew);

   263   return pNew;

   264 }

   266 /*

   267 ** Works like sqlite3Expr() except that it takes an extra Parse*

   268 ** argument and notifies the associated connection object if malloc fails.

   269 */

   270 Expr *sqlite3PExpr(

   271   Parse *pParse,          /* Parsing context */

   272   int op,                 /* Expression opcode */

   273   Expr *pLeft,            /* Left operand */

   274   Expr *pRight,           /* Right operand */

   275   const Token *pToken     /* Argument token */

   276 ){

   277   return sqlite3Expr(pParse->db, op, pLeft, pRight, pToken);

   278 }

   280 /*

   281 ** When doing a nested parse, you can include terms in an expression

   282 ** that look like this:   #0 #1 #2 ...  These terms refer to elements

   283 ** on the stack.  "#0" means the top of the stack.

   284 ** "#1" means the next down on the stack.  And so forth.

   285 **

   286 ** This routine is called by the parser to deal with on of those terms.

   287 ** It immediately generates code to store the value in a memory location.

   288 ** The returns an expression that will code to extract the value from

   289 ** that memory location as needed.

   290 */

   291 Expr *sqlite3RegisterExpr(Parse *pParse, Token *pToken){

   292   Vdbe *v = pParse->pVdbe;

   293   Expr *p;

   294   int depth;

   295   if( pParse->nested==0 ){

   296     sqlite3ErrorMsg(pParse, "near \"%T\": syntax error", pToken);

   297     return sqlite3PExpr(pParse, TK_NULL, 0, 0, 0);

   298   }

   299   if( v==0 ) return 0;

   300   p = sqlite3PExpr(pParse, TK_REGISTER, 0, 0, pToken);

   301   if( p==0 ){

   302     return 0;  /* Malloc failed */

   303   }

   304   depth = atoi((char*)&pToken->z[1]);

   305   p->iTable = pParse->nMem++;

   306   sqlite3VdbeAddOp(v, OP_Dup, depth, 0);

   307   sqlite3VdbeAddOp(v, OP_MemStore, p->iTable, 1);

   308   return p;

   309 }

   311 /*

   312 ** Join two expressions using an AND operator.  If either expression is

   313 ** NULL, then just return the other expression.

   314 */

   315 Expr *sqlite3ExprAnd(sqlite3 *db, Expr *pLeft, Expr *pRight){

   316   if( pLeft==0 ){

   317     return pRight;

   318   }else if( pRight==0 ){

   319     return pLeft;

   320   }else{

   321     return sqlite3Expr(db, TK_AND, pLeft, pRight, 0);

   322   }

   323 }

   325 /*

   326 ** Set the Expr.span field of the given expression to span all

   327 ** text between the two given tokens.

   328 */

   329 void sqlite3ExprSpan(Expr *pExpr, Token *pLeft, Token *pRight){

   330   assert( pRight!=0 );

   331   assert( pLeft!=0 );

   332   if( pExpr && pRight->z && pLeft->z ){

   333     assert( pLeft->dyn==0 || pLeft->z[pLeft->n]==0 );

   334     if( pLeft->dyn==0 && pRight->dyn==0 ){

   335       pExpr->span.z = pLeft->z;

   336       pExpr->span.n = pRight->n + (pRight->z - pLeft->z);

   337     }else{

   338       pExpr->span.z = 0;

   339     }

   340   }

   341 }

   343 /*

   344 ** Construct a new expression node for a function with multiple

   345 ** arguments.

   346 */

   347 Expr *sqlite3ExprFunction(Parse *pParse, ExprList *pList, Token *pToken){

   348   Expr *pNew;

   349   assert( pToken );

   350   pNew = sqlite3DbMallocZero(pParse->db, sizeof(Expr) );

   351   if( pNew==0 ){

   352     sqlite3ExprListDelete(pList); /* Avoid leaking memory when malloc fails */

   353     return 0;

   354   }

   355   pNew->op = TK_FUNCTION;

   356   pNew->pList = pList;

   357   assert( pToken->dyn==0 );

   358   pNew->token = *pToken;

   359   pNew->span = pNew->token;

   361   sqlite3ExprSetHeight(pNew);

   362   return pNew;

   363 }

   365 /*

   366 ** Assign a variable number to an expression that encodes a wildcard

   367 ** in the original SQL statement.

   368 **

   369 ** Wildcards consisting of a single "?" are assigned the next sequential

   370 ** variable number.

   371 **

   372 ** Wildcards of the form "?nnn" are assigned the number "nnn".  We make

   373 ** sure "nnn" is not too be to avoid a denial of service attack when

   374 ** the SQL statement comes from an external source.

   375 **

   376 ** Wildcards of the form ":aaa" or "$aaa" are assigned the same number

   377 ** as the previous instance of the same wildcard.  Or if this is the first

   378 ** instance of the wildcard, the next sequenial variable number is

   379 ** assigned.

   380 */

   381 void sqlite3ExprAssignVarNumber(Parse *pParse, Expr *pExpr){

   382   Token *pToken;

   383   sqlite3 *db = pParse->db;

   385   if( pExpr==0 ) return;

   386   pToken = &pExpr->token;

   387   assert( pToken->n>=1 );

   388   assert( pToken->z!=0 );

   389   assert( pToken->z[0]!=0 );

   390   if( pToken->n==1 ){

   391     /* Wildcard of the form "?".  Assign the next variable number */

   392     pExpr->iTable = ++pParse->nVar;

   393   }else if( pToken->z[0]=='?' ){

   394     /* Wildcard of the form "?nnn".  Convert "nnn" to an integer and

   395     ** use it as the variable number */

   396     int i;

   397     pExpr->iTable = i = atoi((char*)&pToken->z[1]);

   398     if( i<1 || i>SQLITE_MAX_VARIABLE_NUMBER ){

   399       sqlite3ErrorMsg(pParse, "variable number must be between ?1 and ?%d",

   400           SQLITE_MAX_VARIABLE_NUMBER);

   401     }

   402     if( i>pParse->nVar ){

   403       pParse->nVar = i;

   404     }

   405   }else{

   406     /* Wildcards of the form ":aaa" or "$aaa".  Reuse the same variable

   407     ** number as the prior appearance of the same name, or if the name

   408     ** has never appeared before, reuse the same variable number

   409     */

   410     int i, n;

   411     n = pToken->n;

   412     for(i=0; i<pParse->nVarExpr; i++){

   413       Expr *pE;

   414       if( (pE = pParse->apVarExpr[i])!=0

   415           && pE->token.n==n

   416           && memcmp(pE->token.z, pToken->z, n)==0 ){

   417         pExpr->iTable = pE->iTable;

   418         break;

   419       }

   420     }

   421     if( i>=pParse->nVarExpr ){

   422       pExpr->iTable = ++pParse->nVar;

   423       if( pParse->nVarExpr>=pParse->nVarExprAlloc-1 ){

   424         pParse->nVarExprAlloc += pParse->nVarExprAlloc + 10;

   425         pParse->apVarExpr =

   426             sqlite3DbReallocOrFree(

   427               db,

   428               pParse->apVarExpr,

   429               pParse->nVarExprAlloc*sizeof(pParse->apVarExpr[0])

   430             );

   431       }

   432       if( !db->mallocFailed ){

   433         assert( pParse->apVarExpr!=0 );

   434         pParse->apVarExpr[pParse->nVarExpr++] = pExpr;

   435       }

   436     }

   437   }

   438   if( !pParse->nErr && pParse->nVar>SQLITE_MAX_VARIABLE_NUMBER ){

   439     sqlite3ErrorMsg(pParse, "too many SQL variables");

   440   }

   441 }

   443 /*

   444 ** Recursively delete an expression tree.

   445 */

   446 void sqlite3ExprDelete(Expr *p){

   447   if( p==0 ) return;

   448   if( p->span.dyn ) sqlite3_free((char*)p->span.z);

   449   if( p->token.dyn ) sqlite3_free((char*)p->token.z);

   450   sqlite3ExprDelete(p->pLeft);

   451   sqlite3ExprDelete(p->pRight);

   452   sqlite3ExprListDelete(p->pList);

   453   sqlite3SelectDelete(p->pSelect);

   454   sqlite3_free(p);

   455 }

   457 /*

   458 ** The Expr.token field might be a string literal that is quoted.

   459 ** If so, remove the quotation marks.

   460 */

   461 void sqlite3DequoteExpr(sqlite3 *db, Expr *p){

   462   if( ExprHasAnyProperty(p, EP_Dequoted) ){

   463     return;

   464   }

   465   ExprSetProperty(p, EP_Dequoted);

   466   if( p->token.dyn==0 ){

   467     sqlite3TokenCopy(db, &p->token, &p->token);

   468   }

   469   sqlite3Dequote((char*)p->token.z);

   470 }

   473 /*

   474 ** The following group of routines make deep copies of expressions,

   475 ** expression lists, ID lists, and select statements.  The copies can

   476 ** be deleted (by being passed to their respective ...Delete() routines)

   477 ** without effecting the originals.

   478 **

   479 ** The expression list, ID, and source lists return by sqlite3ExprListDup(),

   480 ** sqlite3IdListDup(), and sqlite3SrcListDup() can not be further expanded

   481 ** by subsequent calls to sqlite*ListAppend() routines.

   482 **

   483 ** Any tables that the SrcList might point to are not duplicated.

   484 */

   485 Expr *sqlite3ExprDup(sqlite3 *db, Expr *p){

   486   Expr *pNew;

   487   if( p==0 ) return 0;

   488   pNew = sqlite3DbMallocRaw(db, sizeof(*p) );

   489   if( pNew==0 ) return 0;

   490   memcpy(pNew, p, sizeof(*pNew));

   491   if( p->token.z!=0 ){

   492     pNew->token.z = (u8*)sqlite3DbStrNDup(db, (char*)p->token.z, p->token.n);

   493     pNew->token.dyn = 1;

   494   }else{

   495     assert( pNew->token.z==0 );

   496   }

   497   pNew->span.z = 0;

   498   pNew->pLeft = sqlite3ExprDup(db, p->pLeft);

   499   pNew->pRight = sqlite3ExprDup(db, p->pRight);

   500   pNew->pList = sqlite3ExprListDup(db, p->pList);

   501   pNew->pSelect = sqlite3SelectDup(db, p->pSelect);

   502   return pNew;

   503 }

   504 void sqlite3TokenCopy(sqlite3 *db, Token *pTo, Token *pFrom){

   505   if( pTo->dyn ) sqlite3_free((char*)pTo->z);

   506   if( pFrom->z ){

   507     pTo->n = pFrom->n;

   508     pTo->z = (u8*)sqlite3DbStrNDup(db, (char*)pFrom->z, pFrom->n);

   509     pTo->dyn = 1;

   510   }else{

   511     pTo->z = 0;

   512   }

   513 }

   514 ExprList *sqlite3ExprListDup(sqlite3 *db, ExprList *p){

   515   ExprList *pNew;

   516   struct ExprList_item *pItem, *pOldItem;

   517   int i;

   518   if( p==0 ) return 0;

   519   pNew = sqlite3DbMallocRaw(db, sizeof(*pNew) );

   520   if( pNew==0 ) return 0;

   521   pNew->iECursor = 0;

   522   pNew->nExpr = pNew->nAlloc = p->nExpr;

   523   pNew->a = pItem = sqlite3DbMallocRaw(db,  p->nExpr*sizeof(p->a[0]) );

   524   if( pItem==0 ){

   525     sqlite3_free(pNew);

   526     return 0;

   527   }

   528   pOldItem = p->a;

   529   for(i=0; i<p->nExpr; i++, pItem++, pOldItem++){

   530     Expr *pNewExpr, *pOldExpr;

   531     pItem->pExpr = pNewExpr = sqlite3ExprDup(db, pOldExpr = pOldItem->pExpr);

   532     if( pOldExpr->span.z!=0 && pNewExpr ){

   533       /* Always make a copy of the span for top-level expressions in the

   534       ** expression list.  The logic in SELECT processing that determines

   535       ** the names of columns in the result set needs this information */

   536       sqlite3TokenCopy(db, &pNewExpr->span, &pOldExpr->span);

   537     }

   538     assert( pNewExpr==0 || pNewExpr->span.z!=0

   539             || pOldExpr->span.z==0

   540             || db->mallocFailed );

   541     pItem->zName = sqlite3DbStrDup(db, pOldItem->zName);

   542     pItem->sortOrder = pOldItem->sortOrder;

   543     pItem->isAgg = pOldItem->isAgg;

   544     pItem->done = 0;

   545   }

   546   return pNew;

   547 }

   549 /*

   550 ** If cursors, triggers, views and subqueries are all omitted from

   551 ** the build, then none of the following routines, except for

   552 ** sqlite3SelectDup(), can be called. sqlite3SelectDup() is sometimes

   553 ** called with a NULL argument.

   554 */

   555 #if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_TRIGGER) \

   556  || !defined(SQLITE_OMIT_SUBQUERY)

   557 SrcList *sqlite3SrcListDup(sqlite3 *db, SrcList *p){

   558   SrcList *pNew;

   559   int i;

   560   int nByte;

   561   if( p==0 ) return 0;

   562   nByte = sizeof(*p) + (p->nSrc>0 ? sizeof(p->a[0]) * (p->nSrc-1) : 0);

   563   pNew = sqlite3DbMallocRaw(db, nByte );

   564   if( pNew==0 ) return 0;

   565   pNew->nSrc = pNew->nAlloc = p->nSrc;

   566   for(i=0; i<p->nSrc; i++){

   567     struct SrcList_item *pNewItem = &pNew->a[i];

   568     struct SrcList_item *pOldItem = &p->a[i];

   569     Table *pTab;

   570     pNewItem->zDatabase = sqlite3DbStrDup(db, pOldItem->zDatabase);

   571     pNewItem->zName = sqlite3DbStrDup(db, pOldItem->zName);

   572     pNewItem->zAlias = sqlite3DbStrDup(db, pOldItem->zAlias);

   573     pNewItem->jointype = pOldItem->jointype;

   574     pNewItem->iCursor = pOldItem->iCursor;

   575     pNewItem->isPopulated = pOldItem->isPopulated;

   576     pTab = pNewItem->pTab = pOldItem->pTab;

   577     if( pTab ){

   578       pTab->nRef++;

   579     }

   580     pNewItem->pSelect = sqlite3SelectDup(db, pOldItem->pSelect);

   581     pNewItem->pOn = sqlite3ExprDup(db, pOldItem->pOn);

   582     pNewItem->pUsing = sqlite3IdListDup(db, pOldItem->pUsing);

   583     pNewItem->colUsed = pOldItem->colUsed;

   584   }

   585   return pNew;

   586 }

   587 IdList *sqlite3IdListDup(sqlite3 *db, IdList *p){

   588   IdList *pNew;

   589   int i;

   590   if( p==0 ) return 0;

   591   pNew = sqlite3DbMallocRaw(db, sizeof(*pNew) );

   592   if( pNew==0 ) return 0;

   593   pNew->nId = pNew->nAlloc = p->nId;

   594   pNew->a = sqlite3DbMallocRaw(db, p->nId*sizeof(p->a[0]) );

   595   if( pNew->a==0 ){

   596     sqlite3_free(pNew);

   597     return 0;

   598   }

   599   for(i=0; i<p->nId; i++){

   600     struct IdList_item *pNewItem = &pNew->a[i];

   601     struct IdList_item *pOldItem = &p->a[i];

   602     pNewItem->zName = sqlite3DbStrDup(db, pOldItem->zName);

   603     pNewItem->idx = pOldItem->idx;

   604   }

   605   return pNew;

   606 }

   607 Select *sqlite3SelectDup(sqlite3 *db, Select *p){

   608   Select *pNew;

   609   if( p==0 ) return 0;

   610   pNew = sqlite3DbMallocRaw(db, sizeof(*p) );

   611   if( pNew==0 ) return 0;

   612   pNew->isDistinct = p->isDistinct;

   613   pNew->pEList = sqlite3ExprListDup(db, p->pEList);

   614   pNew->pSrc = sqlite3SrcListDup(db, p->pSrc);

   615   pNew->pWhere = sqlite3ExprDup(db, p->pWhere);

   616   pNew->pGroupBy = sqlite3ExprListDup(db, p->pGroupBy);

   617   pNew->pHaving = sqlite3ExprDup(db, p->pHaving);

   618   pNew->pOrderBy = sqlite3ExprListDup(db, p->pOrderBy);

   619   pNew->op = p->op;

   620   pNew->pPrior = sqlite3SelectDup(db, p->pPrior);

   621   pNew->pLimit = sqlite3ExprDup(db, p->pLimit);

   622   pNew->pOffset = sqlite3ExprDup(db, p->pOffset);

   623   pNew->iLimit = -1;

   624   pNew->iOffset = -1;

   625   pNew->isResolved = p->isResolved;

   626   pNew->isAgg = p->isAgg;

   627   pNew->usesEphm = 0;

   628   pNew->disallowOrderBy = 0;

   629   pNew->pRightmost = 0;

   630   pNew->addrOpenEphm[0] = -1;

   631   pNew->addrOpenEphm[1] = -1;

   632   pNew->addrOpenEphm[2] = -1;

   633   return pNew;

   634 }

   635 #else

   636 Select *sqlite3SelectDup(sqlite3 *db, Select *p){

   637   assert( p==0 );

   638   return 0;

   639 }

   640 #endif

   643 /*

   644 ** Add a new element to the end of an expression list.  If pList is

   645 ** initially NULL, then create a new expression list.

   646 */

   647 ExprList *sqlite3ExprListAppend(

   648   Parse *pParse,          /* Parsing context */

   649   ExprList *pList,        /* List to which to append. Might be NULL */

   650   Expr *pExpr,            /* Expression to be appended */

   651   Token *pName            /* AS keyword for the expression */

   652 ){

   653   sqlite3 *db = pParse->db;

   654   if( pList==0 ){

   655     pList = sqlite3DbMallocZero(db, sizeof(ExprList) );

   656     if( pList==0 ){

   657       goto no_mem;

   658     }

   659     assert( pList->nAlloc==0 );

   660   }

   661   if( pList->nAlloc<=pList->nExpr ){

   662     struct ExprList_item *a;

   663     int n = pList->nAlloc*2 + 4;

   664     a = sqlite3DbRealloc(db, pList->a, n*sizeof(pList->a[0]));

   665     if( a==0 ){

   666       goto no_mem;

   667     }

   668     pList->a = a;

   669     pList->nAlloc = n;

   670   }

   671   assert( pList->a!=0 );

   672   if( pExpr || pName ){

   673     struct ExprList_item *pItem = &pList->a[pList->nExpr++];

   674     memset(pItem, 0, sizeof(*pItem));

   675     pItem->zName = sqlite3NameFromToken(db, pName);

   676     pItem->pExpr = pExpr;

   677   }

   678   return pList;

   680 no_mem:

   681   /* Avoid leaking memory if malloc has failed. */

   682   sqlite3ExprDelete(pExpr);

   683   sqlite3ExprListDelete(pList);

   684   return 0;

   685 }

   687 /*

   688 ** If the expression list pEList contains more than iLimit elements,

   689 ** leave an error message in pParse.

   690 */

   691 void sqlite3ExprListCheckLength(

   692   Parse *pParse,

   693   ExprList *pEList,

   694   int iLimit,

   695   const char *zObject

   696 ){

   697   if( pEList && pEList->nExpr>iLimit ){

   698     sqlite3ErrorMsg(pParse, "too many columns in %s", zObject);

   699   }

   700 }

   703 #if defined(SQLITE_TEST) || SQLITE_MAX_EXPR_DEPTH>0

   704 /* The following three functions, heightOfExpr(), heightOfExprList()

   705 ** and heightOfSelect(), are used to determine the maximum height

   706 ** of any expression tree referenced by the structure passed as the

   707 ** first argument.

   708 **

   709 ** If this maximum height is greater than the current value pointed

   710 ** to by pnHeight, the second parameter, then set *pnHeight to that

   711 ** value.

   712 */

   713 static void heightOfExpr(Expr *p, int *pnHeight){

   714   if( p ){

   715     if( p->nHeight>*pnHeight ){

   716       *pnHeight = p->nHeight;

   717     }

   718   }

   719 }

   720 static void heightOfExprList(ExprList *p, int *pnHeight){

   721   if( p ){

   722     int i;

   723     for(i=0; i<p->nExpr; i++){

   724       heightOfExpr(p->a[i].pExpr, pnHeight);

   725     }

   726   }

   727 }

   728 static void heightOfSelect(Select *p, int *pnHeight){

   729   if( p ){

   730     heightOfExpr(p->pWhere, pnHeight);

   731     heightOfExpr(p->pHaving, pnHeight);

   732     heightOfExpr(p->pLimit, pnHeight);

   733     heightOfExpr(p->pOffset, pnHeight);

   734     heightOfExprList(p->pEList, pnHeight);

   735     heightOfExprList(p->pGroupBy, pnHeight);

   736     heightOfExprList(p->pOrderBy, pnHeight);

   737     heightOfSelect(p->pPrior, pnHeight);

   738   }

   739 }

   741 /*

   742 ** Set the Expr.nHeight variable in the structure passed as an

   743 ** argument. An expression with no children, Expr.pList or

   744 ** Expr.pSelect member has a height of 1. Any other expression

   745 ** has a height equal to the maximum height of any other

   746 ** referenced Expr plus one.

   747 */

   748 void sqlite3ExprSetHeight(Expr *p){

   749   int nHeight = 0;

   750   heightOfExpr(p->pLeft, &nHeight);

   751   heightOfExpr(p->pRight, &nHeight);

   752   heightOfExprList(p->pList, &nHeight);

   753   heightOfSelect(p->pSelect, &nHeight);

   754   p->nHeight = nHeight + 1;

   755 }

   757 /*

   758 ** Return the maximum height of any expression tree referenced

   759 ** by the select statement passed as an argument.

   760 */

   761 int sqlite3SelectExprHeight(Select *p){

   762   int nHeight = 0;

   763   heightOfSelect(p, &nHeight);

   764   return nHeight;

   765 }

   766 #endif

   768 /*

   769 ** Delete an entire expression list.

   770 */

   771 void sqlite3ExprListDelete(ExprList *pList){

   772   int i;

   773   struct ExprList_item *pItem;

   774   if( pList==0 ) return;

   775   assert( pList->a!=0 || (pList->nExpr==0 && pList->nAlloc==0) );

   776   assert( pList->nExpr<=pList->nAlloc );

   777   for(pItem=pList->a, i=0; i<pList->nExpr; i++, pItem++){

   778     sqlite3ExprDelete(pItem->pExpr);

   779     sqlite3_free(pItem->zName);

   780   }

   781   sqlite3_free(pList->a);

   782   sqlite3_free(pList);

   783 }

   785 /*

   786 ** Walk an expression tree.  Call xFunc for each node visited.

   787 **

   788 ** The return value from xFunc determines whether the tree walk continues.

   789 ** 0 means continue walking the tree.  1 means do not walk children

   790 ** of the current node but continue with siblings.  2 means abandon

   791 ** the tree walk completely.

   792 **

   793 ** The return value from this routine is 1 to abandon the tree walk

   794 ** and 0 to continue.

   795 **

   796 ** NOTICE:  This routine does *not* descend into subqueries.

   797 */

   798 static int walkExprList(ExprList *, int (*)(void *, Expr*), void *);

   799 static int walkExprTree(Expr *pExpr, int (*xFunc)(void*,Expr*), void *pArg){

   800   int rc;

   801   if( pExpr==0 ) return 0;

   802   rc = (*xFunc)(pArg, pExpr);

   803   if( rc==0 ){

   804     if( walkExprTree(pExpr->pLeft, xFunc, pArg) ) return 1;

   805     if( walkExprTree(pExpr->pRight, xFunc, pArg) ) return 1;

   806     if( walkExprList(pExpr->pList, xFunc, pArg) ) return 1;

   807   }

   808   return rc>1;

   809 }

   811 /*

   812 ** Call walkExprTree() for every expression in list p.

   813 */

   814 static int walkExprList(ExprList *p, int (*xFunc)(void *, Expr*), void *pArg){

   815   int i;

   816   struct ExprList_item *pItem;

   817   if( !p ) return 0;

   818   for(i=p->nExpr, pItem=p->a; i>0; i--, pItem++){

   819     if( walkExprTree(pItem->pExpr, xFunc, pArg) ) return 1;

   820   }

   821   return 0;

   822 }

   824 /*

   825 ** Call walkExprTree() for every expression in Select p, not including

   826 ** expressions that are part of sub-selects in any FROM clause or the LIMIT

   827 ** or OFFSET expressions..

   828 */

   829 static int walkSelectExpr(Select *p, int (*xFunc)(void *, Expr*), void *pArg){

   830   walkExprList(p->pEList, xFunc, pArg);

   831   walkExprTree(p->pWhere, xFunc, pArg);

   832   walkExprList(p->pGroupBy, xFunc, pArg);

   833   walkExprTree(p->pHaving, xFunc, pArg);

   834   walkExprList(p->pOrderBy, xFunc, pArg);

   835   if( p->pPrior ){

   836     walkSelectExpr(p->pPrior, xFunc, pArg);

   837   }

   838   return 0;

   839 }

   842 /*

   843 ** This routine is designed as an xFunc for walkExprTree().

   844 **

   845 ** pArg is really a pointer to an integer.  If we can tell by looking

   846 ** at pExpr that the expression that contains pExpr is not a constant

   847 ** expression, then set *pArg to 0 and return 2 to abandon the tree walk.

   848 ** If pExpr does does not disqualify the expression from being a constant

   849 ** then do nothing.

   850 **

   851 ** After walking the whole tree, if no nodes are found that disqualify

   852 ** the expression as constant, then we assume the whole expression

   853 ** is constant.  See sqlite3ExprIsConstant() for additional information.

   854 */

   855 static int exprNodeIsConstant(void *pArg, Expr *pExpr){

   856   int *pN = (int*)pArg;

   858   /* If *pArg is 3 then any term of the expression that comes from

   859   ** the ON or USING clauses of a join disqualifies the expression

   860   ** from being considered constant. */

   861   if( (*pN)==3 && ExprHasAnyProperty(pExpr, EP_FromJoin) ){

   862     *pN = 0;

   863     return 2;

   864   }

   866   switch( pExpr->op ){

   867     /* Consider functions to be constant if all their arguments are constant

   868     ** and *pArg==2 */

   869     case TK_FUNCTION:

   870       if( (*pN)==2 ) return 0;

   871       /* Fall through */

   872     case TK_ID:

   873     case TK_COLUMN:

   874     case TK_DOT:

   875     case TK_AGG_FUNCTION:

   876     case TK_AGG_COLUMN:

   877 #ifndef SQLITE_OMIT_SUBQUERY

   878     case TK_SELECT:

   879     case TK_EXISTS:

   880 #endif

   881       *pN = 0;

   882       return 2;

   883     case TK_IN:

   884       if( pExpr->pSelect ){

   885         *pN = 0;

   886         return 2;

   887       }

   888     default:

   889       return 0;

   890   }

   891 }

   893 /*

   894 ** Walk an expression tree.  Return 1 if the expression is constant

   895 ** and 0 if it involves variables or function calls.

   896 **

   897 ** For the purposes of this function, a double-quoted string (ex: "abc")

   898 ** is considered a variable but a single-quoted string (ex: 'abc') is

   899 ** a constant.

   900 */

   901 int sqlite3ExprIsConstant(Expr *p){

   902   int isConst = 1;

   903   walkExprTree(p, exprNodeIsConstant, &isConst);

   904   return isConst;

   905 }

   907 /*

   908 ** Walk an expression tree.  Return 1 if the expression is constant

   909 ** that does no originate from the ON or USING clauses of a join.

   910 ** Return 0 if it involves variables or function calls or terms from

   911 ** an ON or USING clause.

   912 */

   913 int sqlite3ExprIsConstantNotJoin(Expr *p){

   914   int isConst = 3;

   915   walkExprTree(p, exprNodeIsConstant, &isConst);

   916   return isConst!=0;

   917 }

   919 /*

   920 ** Walk an expression tree.  Return 1 if the expression is constant

   921 ** or a function call with constant arguments.  Return and 0 if there

   922 ** are any variables.

   923 **

   924 ** For the purposes of this function, a double-quoted string (ex: "abc")

   925 ** is considered a variable but a single-quoted string (ex: 'abc') is

   926 ** a constant.

   927 */

   928 int sqlite3ExprIsConstantOrFunction(Expr *p){

   929   int isConst = 2;

   930   walkExprTree(p, exprNodeIsConstant, &isConst);

   931   return isConst!=0;

   932 }

   934 /*

   935 ** If the expression p codes a constant integer that is small enough

   936 ** to fit in a 32-bit integer, return 1 and put the value of the integer

   937 ** in *pValue.  If the expression is not an integer or if it is too big

   938 ** to fit in a signed 32-bit integer, return 0 and leave *pValue unchanged.

   939 */

   940 int sqlite3ExprIsInteger(Expr *p, int *pValue){

   941   switch( p->op ){

   942     case TK_INTEGER: {

   943       if( sqlite3GetInt32((char*)p->token.z, pValue) ){

   944         return 1;

   945       }

   946       break;

   947     }

   948     case TK_UPLUS: {

   949       return sqlite3ExprIsInteger(p->pLeft, pValue);

   950     }

   951     case TK_UMINUS: {

   952       int v;

   953       if( sqlite3ExprIsInteger(p->pLeft, &v) ){

   954         *pValue = -v;

   955         return 1;

   956       }

   957       break;

   958     }

   959     default: break;

   960   }

   961   return 0;

   962 }

   964 /*

   965 ** Return TRUE if the given string is a row-id column name.

   966 */

   967 int sqlite3IsRowid(const char *z){

   968   if( sqlite3StrICmp(z, "_ROWID_")==0 ) return 1;

   969   if( sqlite3StrICmp(z, "ROWID")==0 ) return 1;

   970   if( sqlite3StrICmp(z, "OID")==0 ) return 1;

   971   return 0;

   972 }

   974 /*

   975 ** Given the name of a column of the form X.Y.Z or Y.Z or just Z, look up

   976 ** that name in the set of source tables in pSrcList and make the pExpr

   977 ** expression node refer back to that source column.  The following changes

   978 ** are made to pExpr:

   979 **

   980 **    pExpr->iDb           Set the index in db->aDb[] of the database holding

   981 **                         the table.

   982 **    pExpr->iTable        Set to the cursor number for the table obtained

   983 **                         from pSrcList.

   984 **    pExpr->iColumn       Set to the column number within the table.

   985 **    pExpr->op            Set to TK_COLUMN.

   986 **    pExpr->pLeft         Any expression this points to is deleted

   987 **    pExpr->pRight        Any expression this points to is deleted.

   988 **

   989 ** The pDbToken is the name of the database (the "X").  This value may be

   990 ** NULL meaning that name is of the form Y.Z or Z.  Any available database

   991 ** can be used.  The pTableToken is the name of the table (the "Y").  This

   992 ** value can be NULL if pDbToken is also NULL.  If pTableToken is NULL it

   993 ** means that the form of the name is Z and that columns from any table

   994 ** can be used.

   995 **

   996 ** If the name cannot be resolved unambiguously, leave an error message

   997 ** in pParse and return non-zero.  Return zero on success.

   998 */

   999 static int lookupName(

  1000   Parse *pParse,       /* The parsing context */

  1001   Token *pDbToken,     /* Name of the database containing table, or NULL */

  1002   Token *pTableToken,  /* Name of table containing column, or NULL */

  1003   Token *pColumnToken, /* Name of the column. */

  1004   NameContext *pNC,    /* The name context used to resolve the name */

  1005   Expr *pExpr          /* Make this EXPR node point to the selected column */

  1006 ){

  1007   char *zDb = 0;       /* Name of the database.  The "X" in X.Y.Z */

  1008   char *zTab = 0;      /* Name of the table.  The "Y" in X.Y.Z or Y.Z */

  1009   char *zCol = 0;      /* Name of the column.  The "Z" */

  1010   int i, j;            /* Loop counters */

  1011   int cnt = 0;         /* Number of matching column names */

  1012   int cntTab = 0;      /* Number of matching table names */

  1013   sqlite3 *db = pParse->db;  /* The database */

  1014   struct SrcList_item *pItem;       /* Use for looping over pSrcList items */

  1015   struct SrcList_item *pMatch = 0;  /* The matching pSrcList item */

  1016   NameContext *pTopNC = pNC;        /* First namecontext in the list */

  1017   Schema *pSchema = 0;              /* Schema of the expression */

  1019   assert( pColumnToken && pColumnToken->z ); /* The Z in X.Y.Z cannot be NULL */

  1020   zDb = sqlite3NameFromToken(db, pDbToken);

  1021   zTab = sqlite3NameFromToken(db, pTableToken);

  1022   zCol = sqlite3NameFromToken(db, pColumnToken);

  1023   if( db->mallocFailed ){

  1024     goto lookupname_end;

  1025   }

  1027   pExpr->iTable = -1;

  1028   while( pNC && cnt==0 ){

  1029     ExprList *pEList;

  1030     SrcList *pSrcList = pNC->pSrcList;

  1032     if( pSrcList ){

  1033       for(i=0, pItem=pSrcList->a; i<pSrcList->nSrc; i++, pItem++){

  1034         Table *pTab;

  1035         int iDb;

  1036         Column *pCol;

  1038         pTab = pItem->pTab;

  1039         assert( pTab!=0 );

  1040         iDb = sqlite3SchemaToIndex(db, pTab->pSchema);

  1041         assert( pTab->nCol>0 );

  1042         if( zTab ){

  1043           if( pItem->zAlias ){

  1044             char *zTabName = pItem->zAlias;

  1045             if( sqlite3StrICmp(zTabName, zTab)!=0 ) continue;

  1046           }else{

  1047             char *zTabName = pTab->zName;

  1048             if( zTabName==0 || sqlite3StrICmp(zTabName, zTab)!=0 ) continue;

  1049             if( zDb!=0 && sqlite3StrICmp(db->aDb[iDb].zName, zDb)!=0 ){

  1050               continue;

  1051             }

  1052           }

  1053         }

  1054         if( 0==(cntTab++) ){

  1055           pExpr->iTable = pItem->iCursor;

  1056           pSchema = pTab->pSchema;

  1057           pMatch = pItem;

  1058         }

  1059         for(j=0, pCol=pTab->aCol; j<pTab->nCol; j++, pCol++){

  1060           if( sqlite3StrICmp(pCol->zName, zCol)==0 ){

  1061             const char *zColl = pTab->aCol[j].zColl;

  1062             IdList *pUsing;

  1063             cnt++;

  1064             pExpr->iTable = pItem->iCursor;

  1065             pMatch = pItem;

  1066             pSchema = pTab->pSchema;

  1067             /* Substitute the rowid (column -1) for the INTEGER PRIMARY KEY */

  1068             pExpr->iColumn = j==pTab->iPKey ? -1 : j;

  1069             pExpr->affinity = pTab->aCol[j].affinity;

  1070             if( (pExpr->flags & EP_ExpCollate)==0 ){

  1071               pExpr->pColl = sqlite3FindCollSeq(db, ENC(db), zColl,-1, 0);

  1072             }

  1073             if( i<pSrcList->nSrc-1 ){

  1074               if( pItem[1].jointype & JT_NATURAL ){

  1075                 /* If this match occurred in the left table of a natural join,

  1076                 ** then skip the right table to avoid a duplicate match */

  1077                 pItem++;

  1078                 i++;

  1079               }else if( (pUsing = pItem[1].pUsing)!=0 ){

  1080                 /* If this match occurs on a column that is in the USING clause

  1081                 ** of a join, skip the search of the right table of the join

  1082                 ** to avoid a duplicate match there. */

  1083                 int k;

  1084                 for(k=0; k<pUsing->nId; k++){

  1085                   if( sqlite3StrICmp(pUsing->a[k].zName, zCol)==0 ){

  1086                     pItem++;

  1087                     i++;

  1088                     break;

  1089                   }

  1090                 }

  1091               }

  1092             }

  1093             break;

  1094           }

  1095         }

  1096       }

  1097     }

  1099 #ifndef SQLITE_OMIT_TRIGGER

  1100     /* If we have not already resolved the name, then maybe

  1101     ** it is a new.* or old.* trigger argument reference

  1102     */

  1103     if( zDb==0 && zTab!=0 && cnt==0 && pParse->trigStack!=0 ){

  1104       TriggerStack *pTriggerStack = pParse->trigStack;

  1105       Table *pTab = 0;

  1106       if( pTriggerStack->newIdx != -1 && sqlite3StrICmp("new", zTab) == 0 ){

  1107         pExpr->iTable = pTriggerStack->newIdx;

  1108         assert( pTriggerStack->pTab );

  1109         pTab = pTriggerStack->pTab;

  1110       }else if( pTriggerStack->oldIdx != -1 && sqlite3StrICmp("old", zTab)==0 ){

  1111         pExpr->iTable = pTriggerStack->oldIdx;

  1112         assert( pTriggerStack->pTab );

  1113         pTab = pTriggerStack->pTab;

  1114       }

  1116       if( pTab ){

  1117         int iCol;

  1118         Column *pCol = pTab->aCol;

  1120         pSchema = pTab->pSchema;

  1121         cntTab++;

  1122         for(iCol=0; iCol < pTab->nCol; iCol++, pCol++) {

  1123           if( sqlite3StrICmp(pCol->zName, zCol)==0 ){

  1124             const char *zColl = pTab->aCol[iCol].zColl;

  1125             cnt++;

  1126             pExpr->iColumn = iCol==pTab->iPKey ? -1 : iCol;

  1127             pExpr->affinity = pTab->aCol[iCol].affinity;

  1128             if( (pExpr->flags & EP_ExpCollate)==0 ){

  1129               pExpr->pColl = sqlite3FindCollSeq(db, ENC(db), zColl,-1, 0);

  1130             }

  1131             pExpr->pTab = pTab;

  1132             break;

  1133           }

  1134         }

  1135       }

  1136     }

  1137 #endif /* !defined(SQLITE_OMIT_TRIGGER) */

  1139     /*

  1140     ** Perhaps the name is a reference to the ROWID

  1141     */

  1142     if( cnt==0 && cntTab==1 && sqlite3IsRowid(zCol) ){

  1143       cnt = 1;

  1144       pExpr->iColumn = -1;

  1145       pExpr->affinity = SQLITE_AFF_INTEGER;

  1146     }

  1148     /*

  1149     ** If the input is of the form Z (not Y.Z or X.Y.Z) then the name Z

  1150     ** might refer to an result-set alias.  This happens, for example, when

  1151     ** we are resolving names in the WHERE clause of the following command:

  1152     **

  1153     **     SELECT a+b AS x FROM table WHERE x<10;

  1154     **

  1155     ** In cases like this, replace pExpr with a copy of the expression that

  1156     ** forms the result set entry ("a+b" in the example) and return immediately.

  1157     ** Note that the expression in the result set should have already been

  1158     ** resolved by the time the WHERE clause is resolved.

  1159     */

  1160     if( cnt==0 && (pEList = pNC->pEList)!=0 && zTab==0 ){

  1161       for(j=0; j<pEList->nExpr; j++){

  1162         char *zAs = pEList->a[j].zName;

  1163         if( zAs!=0 && sqlite3StrICmp(zAs, zCol)==0 ){

  1164           Expr *pDup, *pOrig;

  1165           assert( pExpr->pLeft==0 && pExpr->pRight==0 );

  1166           assert( pExpr->pList==0 );

  1167           assert( pExpr->pSelect==0 );

  1168           pOrig = pEList->a[j].pExpr;

  1169           if( !pNC->allowAgg && ExprHasProperty(pOrig, EP_Agg) ){

  1170             sqlite3ErrorMsg(pParse, "misuse of aliased aggregate %s", zAs);

  1171             sqlite3_free(zCol);

  1172             return 2;

  1173           }

  1174           pDup = sqlite3ExprDup(db, pOrig);

  1175           if( pExpr->flags & EP_ExpCollate ){

  1176             pDup->pColl = pExpr->pColl;

  1177             pDup->flags |= EP_ExpCollate;

  1178           }

  1179           if( pExpr->span.dyn ) sqlite3_free((char*)pExpr->span.z);

  1180           if( pExpr->token.dyn ) sqlite3_free((char*)pExpr->token.z);

  1181           memcpy(pExpr, pDup, sizeof(*pExpr));

  1182           sqlite3_free(pDup);

  1183           cnt = 1;

  1184           pMatch = 0;

  1185           assert( zTab==0 && zDb==0 );

  1186           goto lookupname_end_2;

  1187         }

  1188       }

  1189     }

  1191     /* Advance to the next name context.  The loop will exit when either

  1192     ** we have a match (cnt>0) or when we run out of name contexts.

  1193     */

  1194     if( cnt==0 ){

  1195       pNC = pNC->pNext;

  1196     }

  1197   }

  1199   /*

  1200   ** If X and Y are NULL (in other words if only the column name Z is

  1201   ** supplied) and the value of Z is enclosed in double-quotes, then

  1202   ** Z is a string literal if it doesn't match any column names.  In that

  1203   ** case, we need to return right away and not make any changes to

  1204   ** pExpr.

  1205   **

  1206   ** Because no reference was made to outer contexts, the pNC->nRef

  1207   ** fields are not changed in any context.

  1208   */

  1209   if( cnt==0 && zTab==0 && pColumnToken->z[0]=='"' ){

  1210     sqlite3_free(zCol);

  1211     return 0;

  1212   }

  1214   /*

  1215   ** cnt==0 means there was not match.  cnt>1 means there were two or

  1216   ** more matches.  Either way, we have an error.

  1217   */

  1218   if( cnt!=1 ){

  1219     char *z = 0;

  1220     char *zErr;

  1221     zErr = cnt==0 ? "no such column: %s" : "ambiguous column name: %s";

  1222     if( zDb ){

  1223       sqlite3SetString(&z, zDb, ".", zTab, ".", zCol, (char*)0);

  1224     }else if( zTab ){

  1225       sqlite3SetString(&z, zTab, ".", zCol, (char*)0);

  1226     }else{

  1227       z = sqlite3StrDup(zCol);

  1228     }

  1229     if( z ){

  1230       sqlite3ErrorMsg(pParse, zErr, z);

  1231       sqlite3_free(z);

  1232       pTopNC->nErr++;

  1233     }else{

  1234       db->mallocFailed = 1;

  1235     }

  1236   }

  1238   /* If a column from a table in pSrcList is referenced, then record

  1239   ** this fact in the pSrcList.a[].colUsed bitmask.  Column 0 causes

  1240   ** bit 0 to be set.  Column 1 sets bit 1.  And so forth.  If the

  1241   ** column number is greater than the number of bits in the bitmask

  1242   ** then set the high-order bit of the bitmask.

  1243   */

  1244   if( pExpr->iColumn>=0 && pMatch!=0 ){

  1245     int n = pExpr->iColumn;

  1246     if( n>=sizeof(Bitmask)*8 ){

  1247       n = sizeof(Bitmask)*8-1;

  1248     }

  1249     assert( pMatch->iCursor==pExpr->iTable );

  1250     pMatch->colUsed |= ((Bitmask)1)<<n;

  1251   }

  1253 lookupname_end:

  1254   /* Clean up and return

  1255   */

  1256   sqlite3_free(zDb);

  1257   sqlite3_free(zTab);

  1258   sqlite3ExprDelete(pExpr->pLeft);

  1259   pExpr->pLeft = 0;

  1260   sqlite3ExprDelete(pExpr->pRight);

  1261   pExpr->pRight = 0;

  1262   pExpr->op = TK_COLUMN;

  1263 lookupname_end_2:

  1264   sqlite3_free(zCol);

  1265   if( cnt==1 ){

  1266     assert( pNC!=0 );

  1267     sqlite3AuthRead(pParse, pExpr, pSchema, pNC->pSrcList);

  1268     if( pMatch && !pMatch->pSelect ){

  1269       pExpr->pTab = pMatch->pTab;

  1270     }

  1271     /* Increment the nRef value on all name contexts from TopNC up to

  1272     ** the point where the name matched. */

  1273     for(;;){

  1274       assert( pTopNC!=0 );

  1275       pTopNC->nRef++;

  1276       if( pTopNC==pNC ) break;

  1277       pTopNC = pTopNC->pNext;

  1278     }

  1279     return 0;

  1280   } else {

  1281     return 1;

  1282   }

  1283 }

  1285 /*

  1286 ** This routine is designed as an xFunc for walkExprTree().

  1287 **

  1288 ** Resolve symbolic names into TK_COLUMN operators for the current

  1289 ** node in the expression tree.  Return 0 to continue the search down

  1290 ** the tree or 2 to abort the tree walk.

  1291 **

  1292 ** This routine also does error checking and name resolution for

  1293 ** function names.  The operator for aggregate functions is changed

  1294 ** to TK_AGG_FUNCTION.

  1295 */

  1296 static int nameResolverStep(void *pArg, Expr *pExpr){

  1297   NameContext *pNC = (NameContext*)pArg;

  1298   Parse *pParse;

  1300   if( pExpr==0 ) return 1;

  1301   assert( pNC!=0 );

  1302   pParse = pNC->pParse;

  1304   if( ExprHasAnyProperty(pExpr, EP_Resolved) ) return 1;

  1305   ExprSetProperty(pExpr, EP_Resolved);

  1306 #ifndef NDEBUG

  1307   if( pNC->pSrcList && pNC->pSrcList->nAlloc>0 ){

  1308     SrcList *pSrcList = pNC->pSrcList;

  1309     int i;

  1310     for(i=0; i<pNC->pSrcList->nSrc; i++){

  1311       assert( pSrcList->a[i].iCursor>=0 && pSrcList->a[i].iCursor<pParse->nTab);

  1312     }

  1313   }

  1314 #endif

  1315   switch( pExpr->op ){

  1316     /* Double-quoted strings (ex: "abc") are used as identifiers if

  1317     ** possible.  Otherwise they remain as strings.  Single-quoted

  1318     ** strings (ex: 'abc') are always string literals.

  1319     */

  1320     case TK_STRING: {

  1321       if( pExpr->token.z[0]=='\'' ) break;

  1322       /* Fall thru into the TK_ID case if this is a double-quoted string */

  1323     }

  1324     /* A lone identifier is the name of a column.

  1325     */

  1326     case TK_ID: {

  1327       lookupName(pParse, 0, 0, &pExpr->token, pNC, pExpr);

  1328       return 1;

  1329     }

  1331     /* A table name and column name:     ID.ID

  1332     ** Or a database, table and column:  ID.ID.ID

  1333     */

  1334     case TK_DOT: {

  1335       Token *pColumn;

  1336       Token *pTable;

  1337       Token *pDb;

  1338       Expr *pRight;

  1340       /* if( pSrcList==0 ) break; */

  1341       pRight = pExpr->pRight;

  1342       if( pRight->op==TK_ID ){

  1343         pDb = 0;

  1344         pTable = &pExpr->pLeft->token;

  1345         pColumn = &pRight->token;

  1346       }else{

  1347         assert( pRight->op==TK_DOT );

  1348         pDb = &pExpr->pLeft->token;

  1349         pTable = &pRight->pLeft->token;

  1350         pColumn = &pRight->pRight->token;

  1351       }

  1352       lookupName(pParse, pDb, pTable, pColumn, pNC, pExpr);

  1353       return 1;

  1354     }

  1356     /* Resolve function names

  1357     */

  1358     case TK_CONST_FUNC:

  1359     case TK_FUNCTION: {

  1360       ExprList *pList = pExpr->pList;    /* The argument list */

  1361       int n = pList ? pList->nExpr : 0;  /* Number of arguments */

  1362       int no_such_func = 0;       /* True if no such function exists */

  1363       int wrong_num_args = 0;     /* True if wrong number of arguments */

  1364       int is_agg = 0;             /* True if is an aggregate function */

  1365       int i;

  1366       int auth;                   /* Authorization to use the function */

  1367       int nId;                    /* Number of characters in function name */

  1368       const char *zId;            /* The function name. */

  1369       FuncDef *pDef;              /* Information about the function */

  1370       int enc = ENC(pParse->db);  /* The database encoding */

  1372       zId = (char*)pExpr->token.z;

  1373       nId = pExpr->token.n;

  1374       pDef = sqlite3FindFunction(pParse->db, zId, nId, n, enc, 0);

  1375       if( pDef==0 ){

  1376         pDef = sqlite3FindFunction(pParse->db, zId, nId, -1, enc, 0);

  1377         if( pDef==0 ){

  1378           no_such_func = 1;

  1379         }else{

  1380           wrong_num_args = 1;

  1381         }

  1382       }else{

  1383         is_agg = pDef->xFunc==0;

  1384       }

  1385 #ifndef SQLITE_OMIT_AUTHORIZATION

  1386       if( pDef ){

  1387         auth = sqlite3AuthCheck(pParse, SQLITE_FUNCTION, 0, pDef->zName, 0);

  1388         if( auth!=SQLITE_OK ){

  1389           if( auth==SQLITE_DENY ){

  1390             sqlite3ErrorMsg(pParse, "not authorized to use function: %s",

  1391                                     pDef->zName);

  1392             pNC->nErr++;

  1393           }

  1394           pExpr->op = TK_NULL;

  1395           return 1;

  1396         }

  1397       }

  1398 #endif

  1399       if( is_agg && !pNC->allowAgg ){

  1400         sqlite3ErrorMsg(pParse, "misuse of aggregate function %.*s()", nId,zId);

  1401         pNC->nErr++;

  1402         is_agg = 0;

  1403       }else if( no_such_func ){

  1404         sqlite3ErrorMsg(pParse, "no such function: %.*s", nId, zId);

  1405         pNC->nErr++;

  1406       }else if( wrong_num_args ){

  1407         sqlite3ErrorMsg(pParse,"wrong number of arguments to function %.*s()",

  1408              nId, zId);

  1409         pNC->nErr++;

  1410       }

  1411       if( is_agg ){

  1412         pExpr->op = TK_AGG_FUNCTION;

  1413         pNC->hasAgg = 1;

  1414       }

  1415       if( is_agg ) pNC->allowAgg = 0;

  1416       for(i=0; pNC->nErr==0 && i<n; i++){

  1417         walkExprTree(pList->a[i].pExpr, nameResolverStep, pNC);

  1418       }

  1419       if( is_agg ) pNC->allowAgg = 1;

  1420       /* FIX ME:  Compute pExpr->affinity based on the expected return

  1421       ** type of the function

  1422       */

  1423       return is_agg;

  1424     }

  1425 #ifndef SQLITE_OMIT_SUBQUERY

  1426     case TK_SELECT:

  1427     case TK_EXISTS:

  1428 #endif

  1429     case TK_IN: {

  1430       if( pExpr->pSelect ){

  1431         int nRef = pNC->nRef;

  1432 #ifndef SQLITE_OMIT_CHECK

  1433         if( pNC->isCheck ){

  1434           sqlite3ErrorMsg(pParse,"subqueries prohibited in CHECK constraints");

  1435         }

  1436 #endif

  1437         sqlite3SelectResolve(pParse, pExpr->pSelect, pNC);

  1438         assert( pNC->nRef>=nRef );

  1439         if( nRef!=pNC->nRef ){

  1440           ExprSetProperty(pExpr, EP_VarSelect);

  1441         }

  1442       }

  1443       break;

  1444     }

  1445 #ifndef SQLITE_OMIT_CHECK

  1446     case TK_VARIABLE: {

  1447       if( pNC->isCheck ){

  1448         sqlite3ErrorMsg(pParse,"parameters prohibited in CHECK constraints");

  1449       }

  1450       break;

  1451     }

  1452 #endif

  1453   }

  1454   return 0;

  1455 }

  1457 /*

  1458 ** This routine walks an expression tree and resolves references to

  1459 ** table columns.  Nodes of the form ID.ID or ID resolve into an

  1460 ** index to the table in the table list and a column offset.  The

  1461 ** Expr.opcode for such nodes is changed to TK_COLUMN.  The Expr.iTable

  1462 ** value is changed to the index of the referenced table in pTabList

  1463 ** plus the "base" value.  The base value will ultimately become the

  1464 ** VDBE cursor number for a cursor that is pointing into the referenced

  1465 ** table.  The Expr.iColumn value is changed to the index of the column

  1466 ** of the referenced table.  The Expr.iColumn value for the special

  1467 ** ROWID column is -1.  Any INTEGER PRIMARY KEY column is tried as an

  1468 ** alias for ROWID.

  1469 **

  1470 ** Also resolve function names and check the functions for proper

  1471 ** usage.  Make sure all function names are recognized and all functions

  1472 ** have the correct number of arguments.  Leave an error message

  1473 ** in pParse->zErrMsg if anything is amiss.  Return the number of errors.

  1474 **

  1475 ** If the expression contains aggregate functions then set the EP_Agg

  1476 ** property on the expression.

  1477 */

  1478 int sqlite3ExprResolveNames(

  1479   NameContext *pNC,       /* Namespace to resolve expressions in. */

  1480   Expr *pExpr             /* The expression to be analyzed. */

  1481 ){

  1482   int savedHasAgg;

  1483   if( pExpr==0 ) return 0;

  1484 #if defined(SQLITE_TEST) || SQLITE_MAX_EXPR_DEPTH>0

  1485   if( (pExpr->nHeight+pNC->pParse->nHeight)>SQLITE_MAX_EXPR_DEPTH ){

  1486     sqlite3ErrorMsg(pNC->pParse,

  1487        "Expression tree is too large (maximum depth %d)",

  1488        SQLITE_MAX_EXPR_DEPTH

  1489     );

  1490     return 1;

  1491   }

  1492   pNC->pParse->nHeight += pExpr->nHeight;

  1493 #endif

  1494   savedHasAgg = pNC->hasAgg;

  1495   pNC->hasAgg = 0;

  1496   walkExprTree(pExpr, nameResolverStep, pNC);

  1497 #if defined(SQLITE_TEST) || SQLITE_MAX_EXPR_DEPTH>0

  1498   pNC->pParse->nHeight -= pExpr->nHeight;

  1499 #endif

  1500   if( pNC->nErr>0 ){

  1501     ExprSetProperty(pExpr, EP_Error);

  1502   }

  1503   if( pNC->hasAgg ){

  1504     ExprSetProperty(pExpr, EP_Agg);

  1505   }else if( savedHasAgg ){

  1506     pNC->hasAgg = 1;

  1507   }

  1508   return ExprHasProperty(pExpr, EP_Error);

  1509 }

  1511 /*

  1512 ** A pointer instance of this structure is used to pass information

  1513 ** through walkExprTree into codeSubqueryStep().

  1514 */

  1515 typedef struct QueryCoder QueryCoder;

  1516 struct QueryCoder {

  1517   Parse *pParse;       /* The parsing context */

  1518   NameContext *pNC;    /* Namespace of first enclosing query */

  1519 };

  1522 /*

  1523 ** Generate code for scalar subqueries used as an expression

  1524 ** and IN operators.  Examples:

  1525 **

  1526 **     (SELECT a FROM b)          -- subquery

  1527 **     EXISTS (SELECT a FROM b)   -- EXISTS subquery

  1528 **     x IN (4,5,11)              -- IN operator with list on right-hand side

  1529 **     x IN (SELECT a FROM b)     -- IN operator with subquery on the right

  1530 **

  1531 ** The pExpr parameter describes the expression that contains the IN

  1532 ** operator or subquery.

  1533 */

  1534 #ifndef SQLITE_OMIT_SUBQUERY

  1535 void sqlite3CodeSubselect(Parse *pParse, Expr *pExpr){

  1536   int testAddr = 0;                       /* One-time test address */

  1537   Vdbe *v = sqlite3GetVdbe(pParse);

  1538   if( v==0 ) return;

  1541   /* This code must be run in its entirety every time it is encountered

  1542   ** if any of the following is true:

  1543   **

  1544   **    *  The right-hand side is a correlated subquery

  1545   **    *  The right-hand side is an expression list containing variables

  1546   **    *  We are inside a trigger

  1547   **

  1548   ** If all of the above are false, then we can run this code just once

  1549   ** save the results, and reuse the same result on subsequent invocations.

  1550   */

  1551   if( !ExprHasAnyProperty(pExpr, EP_VarSelect) && !pParse->trigStack ){

  1552     int mem = pParse->nMem++;

  1553     sqlite3VdbeAddOp(v, OP_MemLoad, mem, 0);

  1554     testAddr = sqlite3VdbeAddOp(v, OP_If, 0, 0);

  1555     assert( testAddr>0 || pParse->db->mallocFailed );

  1556     sqlite3VdbeAddOp(v, OP_MemInt, 1, mem);

  1557   }

  1559   switch( pExpr->op ){

  1560     case TK_IN: {

  1561       char affinity;

  1562       KeyInfo keyInfo;

  1563       int addr;        /* Address of OP_OpenEphemeral instruction */

  1565       affinity = sqlite3ExprAffinity(pExpr->pLeft);

  1567       /* Whether this is an 'x IN(SELECT...)' or an 'x IN(<exprlist>)'

  1568       ** expression it is handled the same way. A virtual table is

  1569       ** filled with single-field index keys representing the results

  1570       ** from the SELECT or the <exprlist>.

  1571       **

  1572       ** If the 'x' expression is a column value, or the SELECT...

  1573       ** statement returns a column value, then the affinity of that

  1574       ** column is used to build the index keys. If both 'x' and the

  1575       ** SELECT... statement are columns, then numeric affinity is used

  1576       ** if either column has NUMERIC or INTEGER affinity. If neither

  1577       ** 'x' nor the SELECT... statement are columns, then numeric affinity

  1578       ** is used.

  1579       */

  1580       pExpr->iTable = pParse->nTab++;

  1581       addr = sqlite3VdbeAddOp(v, OP_OpenEphemeral, pExpr->iTable, 0);

  1582       memset(&keyInfo, 0, sizeof(keyInfo));

  1583       keyInfo.nField = 1;

  1584       sqlite3VdbeAddOp(v, OP_SetNumColumns, pExpr->iTable, 1);

  1586       if( pExpr->pSelect ){

  1587         /* Case 1:     expr IN (SELECT ...)

  1588         **

  1589         ** Generate code to write the results of the select into the temporary

  1590         ** table allocated and opened above.

  1591         */

  1592         int iParm = pExpr->iTable +  (((int)affinity)<<16);

  1593         ExprList *pEList;

  1594         assert( (pExpr->iTable&0x0000FFFF)==pExpr->iTable );

  1595         if( sqlite3Select(pParse, pExpr->pSelect, SRT_Set, iParm, 0, 0, 0, 0) ){

  1596           return;

  1597         }

  1598         pEList = pExpr->pSelect->pEList;

  1599         if( pEList && pEList->nExpr>0 ){

  1600           keyInfo.aColl[0] = sqlite3BinaryCompareCollSeq(pParse, pExpr->pLeft,

  1601               pEList->a[0].pExpr);

  1602         }

  1603       }else if( pExpr->pList ){

  1604         /* Case 2:     expr IN (exprlist)

  1605         **

  1606         ** For each expression, build an index key from the evaluation and

  1607         ** store it in the temporary table. If <expr> is a column, then use

  1608         ** that columns affinity when building index keys. If <expr> is not

  1609         ** a column, use numeric affinity.

  1610         */

  1611         int i;

  1612         ExprList *pList = pExpr->pList;

  1613         struct ExprList_item *pItem;

  1615         if( !affinity ){

  1616           affinity = SQLITE_AFF_NONE;

  1617         }

  1618         keyInfo.aColl[0] = pExpr->pLeft->pColl;

  1620         /* Loop through each expression in <exprlist>. */

  1621         for(i=pList->nExpr, pItem=pList->a; i>0; i--, pItem++){

  1622           Expr *pE2 = pItem->pExpr;

  1624           /* If the expression is not constant then we will need to

  1625           ** disable the test that was generated above that makes sure

  1626           ** this code only executes once.  Because for a non-constant

  1627           ** expression we need to rerun this code each time.

  1628           */

  1629           if( testAddr>0 && !sqlite3ExprIsConstant(pE2) ){

  1630             sqlite3VdbeChangeToNoop(v, testAddr-1, 3);

  1631             testAddr = 0;

  1632           }

  1634           /* Evaluate the expression and insert it into the temp table */

  1635           sqlite3ExprCode(pParse, pE2);

  1636           sqlite3VdbeOp3(v, OP_MakeRecord, 1, 0, &affinity, 1);

  1637           sqlite3VdbeAddOp(v, OP_IdxInsert, pExpr->iTable, 0);

  1638         }

  1639       }

  1640       sqlite3VdbeChangeP3(v, addr, (void *)&keyInfo, P3_KEYINFO);

  1641       break;

  1642     }

  1644     case TK_EXISTS:

  1645     case TK_SELECT: {

  1646       /* This has to be a scalar SELECT.  Generate code to put the

  1647       ** value of this select in a memory cell and record the number

  1648       ** of the memory cell in iColumn.

  1649       */

  1650       static const Token one = { (u8*)"1", 0, 1 };

  1651       Select *pSel;

  1652       int iMem;

  1653       int sop;

  1655       pExpr->iColumn = iMem = pParse->nMem++;

  1656       pSel = pExpr->pSelect;

  1657       if( pExpr->op==TK_SELECT ){

  1658         sop = SRT_Mem;

  1659         sqlite3VdbeAddOp(v, OP_MemNull, iMem, 0);

  1660         VdbeComment((v, "# Init subquery result"));

  1661       }else{

  1662         sop = SRT_Exists;

  1663         sqlite3VdbeAddOp(v, OP_MemInt, 0, iMem);

  1664         VdbeComment((v, "# Init EXISTS result"));

  1665       }

  1666       sqlite3ExprDelete(pSel->pLimit);

  1667       pSel->pLimit = sqlite3PExpr(pParse, TK_INTEGER, 0, 0, &one);

  1668       if( sqlite3Select(pParse, pSel, sop, iMem, 0, 0, 0, 0) ){

  1669         return;

  1670       }

  1671       break;

  1672     }

  1673   }

  1675   if( testAddr ){

  1676     sqlite3VdbeJumpHere(v, testAddr);

  1677   }

  1679   return;

  1680 }

  1681 #endif /* SQLITE_OMIT_SUBQUERY */

  1683 /*

  1684 ** Generate an instruction that will put the integer describe by

  1685 ** text z[0..n-1] on the stack.

  1686 */

  1687 static void codeInteger(Vdbe *v, const char *z, int n){

  1688   assert( z || v==0 || sqlite3VdbeDb(v)->mallocFailed );

  1689   if( z ){

  1690     int i;

  1691     if( sqlite3GetInt32(z, &i) ){

  1692       sqlite3VdbeAddOp(v, OP_Integer, i, 0);

  1693     }else if( sqlite3FitsIn64Bits(z) ){

  1694       sqlite3VdbeOp3(v, OP_Int64, 0, 0, z, n);

  1695     }else{

  1696       sqlite3VdbeOp3(v, OP_Real, 0, 0, z, n);

  1697     }

  1698   }

  1699 }

  1702 /*

  1703 ** Generate code that will extract the iColumn-th column from

  1704 ** table pTab and push that column value on the stack.  There

  1705 ** is an open cursor to pTab in iTable.  If iColumn<0 then

  1706 ** code is generated that extracts the rowid.

  1707 */

  1708 void sqlite3ExprCodeGetColumn(Vdbe *v, Table *pTab, int iColumn, int iTable){

  1709   if( iColumn<0 ){

  1710     int op = (pTab && IsVirtual(pTab)) ? OP_VRowid : OP_Rowid;

  1711     sqlite3VdbeAddOp(v, op, iTable, 0);

  1712   }else if( pTab==0 ){

  1713     sqlite3VdbeAddOp(v, OP_Column, iTable, iColumn);

  1714   }else{

  1715     int op = IsVirtual(pTab) ? OP_VColumn : OP_Column;

  1716     sqlite3VdbeAddOp(v, op, iTable, iColumn);

  1717     sqlite3ColumnDefault(v, pTab, iColumn);

  1718 #ifndef SQLITE_OMIT_FLOATING_POINT

  1719     if( pTab->aCol[iColumn].affinity==SQLITE_AFF_REAL ){

  1720       sqlite3VdbeAddOp(v, OP_RealAffinity, 0, 0);

  1721     }

  1722 #endif

  1723   }

  1724 }

  1726 /*

  1727 ** Generate code into the current Vdbe to evaluate the given

  1728 ** expression and leave the result on the top of stack.

  1729 **

  1730 ** This code depends on the fact that certain token values (ex: TK_EQ)

  1731 ** are the same as opcode values (ex: OP_Eq) that implement the corresponding

  1732 ** operation.  Special comments in vdbe.c and the mkopcodeh.awk script in

  1733 ** the make process cause these values to align.  Assert()s in the code

  1734 ** below verify that the numbers are aligned correctly.

  1735 */

  1736 void sqlite3ExprCode(Parse *pParse, Expr *pExpr){

  1737   Vdbe *v = pParse->pVdbe;

  1738   int op;

  1739   int stackChng = 1;    /* Amount of change to stack depth */

  1741   if( v==0 ) return;

  1742   if( pExpr==0 ){

  1743     sqlite3VdbeAddOp(v, OP_Null, 0, 0);

  1744     return;

  1745   }

  1746   op = pExpr->op;

  1747   switch( op ){

  1748     case TK_AGG_COLUMN: {

  1749       AggInfo *pAggInfo = pExpr->pAggInfo;

  1750       struct AggInfo_col *pCol = &pAggInfo->aCol[pExpr->iAgg];

  1751       if( !pAggInfo->directMode ){

  1752         sqlite3VdbeAddOp(v, OP_MemLoad, pCol->iMem, 0);

  1753         break;

  1754       }else if( pAggInfo->useSortingIdx ){

  1755         sqlite3VdbeAddOp(v, OP_Column, pAggInfo->sortingIdx,

  1756                               pCol->iSorterColumn);

  1757         break;

  1758       }

  1759       /* Otherwise, fall thru into the TK_COLUMN case */

  1760     }

  1761     case TK_COLUMN: {

  1762       if( pExpr->iTable<0 ){

  1763         /* This only happens when coding check constraints */

  1764         assert( pParse->ckOffset>0 );

  1765         sqlite3VdbeAddOp(v, OP_Dup, pParse->ckOffset-pExpr->iColumn-1, 1);

  1766       }else{

  1767         sqlite3ExprCodeGetColumn(v, pExpr->pTab, pExpr->iColumn, pExpr->iTable);

  1768       }

  1769       break;

  1770     }

  1771     case TK_INTEGER: {

  1772       codeInteger(v, (char*)pExpr->token.z, pExpr->token.n);

  1773       break;

  1774     }

  1775     case TK_FLOAT:

  1776     case TK_STRING: {

  1777       assert( TK_FLOAT==OP_Real );

  1778       assert( TK_STRING==OP_String8 );

  1779       sqlite3DequoteExpr(pParse->db, pExpr);

  1780       sqlite3VdbeOp3(v, op, 0, 0, (char*)pExpr->token.z, pExpr->token.n);

  1781       break;

  1782     }

  1783     case TK_NULL: {

  1784       sqlite3VdbeAddOp(v, OP_Null, 0, 0);

  1785       break;

  1786     }

  1787 #ifndef SQLITE_OMIT_BLOB_LITERAL

  1788     case TK_BLOB: {

  1789       int n;

  1790       const char *z;

  1791       assert( TK_BLOB==OP_HexBlob );

  1792       n = pExpr->token.n - 3;

  1793       z = (char*)pExpr->token.z + 2;

  1794       assert( n>=0 );

  1795       if( n==0 ){

  1796         z = "";

  1797       }

  1798       sqlite3VdbeOp3(v, op, 0, 0, z, n);

  1799       break;

  1800     }

  1801 #endif

  1802     case TK_VARIABLE: {

  1803       sqlite3VdbeAddOp(v, OP_Variable, pExpr->iTable, 0);

  1804       if( pExpr->token.n>1 ){

  1805         sqlite3VdbeChangeP3(v, -1, (char*)pExpr->token.z, pExpr->token.n);

  1806       }

  1807       break;

  1808     }

  1809     case TK_REGISTER: {

  1810       sqlite3VdbeAddOp(v, OP_MemLoad, pExpr->iTable, 0);

  1811       break;

  1812     }

  1813 #ifndef SQLITE_OMIT_CAST

  1814     case TK_CAST: {

  1815       /* Expressions of the form:   CAST(pLeft AS token) */

  1816       int aff, to_op;

  1817       sqlite3ExprCode(pParse, pExpr->pLeft);

  1818       aff = sqlite3AffinityType(&pExpr->token);

  1819       to_op = aff - SQLITE_AFF_TEXT + OP_ToText;

  1820       assert( to_op==OP_ToText    || aff!=SQLITE_AFF_TEXT    );

  1821       assert( to_op==OP_ToBlob    || aff!=SQLITE_AFF_NONE    );

  1822       assert( to_op==OP_ToNumeric || aff!=SQLITE_AFF_NUMERIC );

  1823       assert( to_op==OP_ToInt     || aff!=SQLITE_AFF_INTEGER );

  1824       assert( to_op==OP_ToReal    || aff!=SQLITE_AFF_REAL    );

  1825       sqlite3VdbeAddOp(v, to_op, 0, 0);

  1826       stackChng = 0;

  1827       break;

  1828     }

  1829 #endif /* SQLITE_OMIT_CAST */

  1830     case TK_LT:

  1831     case TK_LE:

  1832     case TK_GT:

  1833     case TK_GE:

  1834     case TK_NE:

  1835     case TK_EQ: {

  1836       assert( TK_LT==OP_Lt );

  1837       assert( TK_LE==OP_Le );

  1838       assert( TK_GT==OP_Gt );

  1839       assert( TK_GE==OP_Ge );

  1840       assert( TK_EQ==OP_Eq );

  1841       assert( TK_NE==OP_Ne );

  1842       sqlite3ExprCode(pParse, pExpr->pLeft);

  1843       sqlite3ExprCode(pParse, pExpr->pRight);

  1844       codeCompare(pParse, pExpr->pLeft, pExpr->pRight, op, 0, 0);

  1845       stackChng = -1;

  1846       break;

  1847     }

  1848     case TK_AND:

  1849     case TK_OR:

  1850     case TK_PLUS:

  1851     case TK_STAR:

  1852     case TK_MINUS:

  1853     case TK_REM:

  1854     case TK_BITAND:

  1855     case TK_BITOR:

  1856     case TK_SLASH:

  1857     case TK_LSHIFT:

  1858     case TK_RSHIFT:

  1859     case TK_CONCAT: {

  1860       assert( TK_AND==OP_And );

  1861       assert( TK_OR==OP_Or );

  1862       assert( TK_PLUS==OP_Add );

  1863       assert( TK_MINUS==OP_Subtract );

  1864       assert( TK_REM==OP_Remainder );

  1865       assert( TK_BITAND==OP_BitAnd );

  1866       assert( TK_BITOR==OP_BitOr );

  1867       assert( TK_SLASH==OP_Divide );

  1868       assert( TK_LSHIFT==OP_ShiftLeft );

  1869       assert( TK_RSHIFT==OP_ShiftRight );

  1870       assert( TK_CONCAT==OP_Concat );

  1871       sqlite3ExprCode(pParse, pExpr->pLeft);

  1872       sqlite3ExprCode(pParse, pExpr->pRight);

  1873       sqlite3VdbeAddOp(v, op, 0, 0);

  1874       stackChng = -1;

  1875       break;

  1876     }

  1877     case TK_UMINUS: {

  1878       Expr *pLeft = pExpr->pLeft;

  1879       assert( pLeft );

  1880       if( pLeft->op==TK_FLOAT || pLeft->op==TK_INTEGER ){

  1881         Token *p = &pLeft->token;

  1882         char *z = sqlite3MPrintf(pParse->db, "-%.*s", p->n, p->z);

  1883         if( pLeft->op==TK_FLOAT ){

  1884           sqlite3VdbeOp3(v, OP_Real, 0, 0, z, p->n+1);

  1885         }else{

  1886           codeInteger(v, z, p->n+1);

  1887         }

  1888         sqlite3_free(z);

  1889         break;

  1890       }

  1891       /* Fall through into TK_NOT */

  1892     }

  1893     case TK_BITNOT:

  1894     case TK_NOT: {

  1895       assert( TK_BITNOT==OP_BitNot );

  1896       assert( TK_NOT==OP_Not );

  1897       sqlite3ExprCode(pParse, pExpr->pLeft);

  1898       sqlite3VdbeAddOp(v, op, 0, 0);

  1899       stackChng = 0;

  1900       break;

  1901     }

  1902     case TK_ISNULL:

  1903     case TK_NOTNULL: {

  1904       int dest;

  1905       assert( TK_ISNULL==OP_IsNull );

  1906       assert( TK_NOTNULL==OP_NotNull );

  1907       sqlite3VdbeAddOp(v, OP_Integer, 1, 0);

  1908       sqlite3ExprCode(pParse, pExpr->pLeft);

  1909       dest = sqlite3VdbeCurrentAddr(v) + 2;

  1910       sqlite3VdbeAddOp(v, op, 1, dest);

  1911       sqlite3VdbeAddOp(v, OP_AddImm, -1, 0);

  1912       stackChng = 0;

  1913       break;

  1914     }

  1915     case TK_AGG_FUNCTION: {

  1916       AggInfo *pInfo = pExpr->pAggInfo;

  1917       if( pInfo==0 ){

  1918         sqlite3ErrorMsg(pParse, "misuse of aggregate: %T",

  1919             &pExpr->span);

  1920       }else{

  1921         sqlite3VdbeAddOp(v, OP_MemLoad, pInfo->aFunc[pExpr->iAgg].iMem, 0);

  1922       }

  1923       break;

  1924     }

  1925     case TK_CONST_FUNC:

  1926     case TK_FUNCTION: {

  1927       ExprList *pList = pExpr->pList;

  1928       int nExpr = pList ? pList->nExpr : 0;

  1929       FuncDef *pDef;

  1930       int nId;

  1931       const char *zId;

  1932       int constMask = 0;

  1933       int i;

  1934       sqlite3 *db = pParse->db;

  1935       u8 enc = ENC(db);

  1936       CollSeq *pColl = 0;

  1938       zId = (char*)pExpr->token.z;

  1939       nId = pExpr->token.n;

  1940       pDef = sqlite3FindFunction(pParse->db, zId, nId, nExpr, enc, 0);

  1941       assert( pDef!=0 );

  1942       nExpr = sqlite3ExprCodeExprList(pParse, pList);

  1943 #ifndef SQLITE_OMIT_VIRTUALTABLE

  1944       /* Possibly overload the function if the first argument is

  1945       ** a virtual table column.

  1946       **

  1947       ** For infix functions (LIKE, GLOB, REGEXP, and MATCH) use the

  1948       ** second argument, not the first, as the argument to test to

  1949       ** see if it is a column in a virtual table.  This is done because

  1950       ** the left operand of infix functions (the operand we want to

  1951       ** control overloading) ends up as the second argument to the

  1952       ** function.  The expression "A glob B" is equivalent to

  1953       ** "glob(B,A).  We want to use the A in "A glob B" to test

  1954       ** for function overloading.  But we use the B term in "glob(B,A)".

  1955       */

  1956       if( nExpr>=2 && (pExpr->flags & EP_InfixFunc) ){

  1957         pDef = sqlite3VtabOverloadFunction(db, pDef, nExpr, pList->a[1].pExpr);

  1958       }else if( nExpr>0 ){

  1959         pDef = sqlite3VtabOverloadFunction(db, pDef, nExpr, pList->a[0].pExpr);

  1960       }

  1961 #endif

  1962       for(i=0; i<nExpr && i<32; i++){

  1963         if( sqlite3ExprIsConstant(pList->a[i].pExpr) ){

  1964           constMask |= (1<<i);

  1965         }

  1966         if( pDef->needCollSeq && !pColl ){

  1967           pColl = sqlite3ExprCollSeq(pParse, pList->a[i].pExpr);

  1968         }

  1969       }

  1970       if( pDef->needCollSeq ){

  1971         if( !pColl ) pColl = pParse->db->pDfltColl;

  1972         sqlite3VdbeOp3(v, OP_CollSeq, 0, 0, (char *)pColl, P3_COLLSEQ);

  1973       }

  1974       sqlite3VdbeOp3(v, OP_Function, constMask, nExpr, (char*)pDef, P3_FUNCDEF);

  1975       stackChng = 1-nExpr;

  1976       break;

  1977     }

  1978 #ifndef SQLITE_OMIT_SUBQUERY

  1979     case TK_EXISTS:

  1980     case TK_SELECT: {

  1981       if( pExpr->iColumn==0 ){

  1982         sqlite3CodeSubselect(pParse, pExpr);

  1983       }

  1984       sqlite3VdbeAddOp(v, OP_MemLoad, pExpr->iColumn, 0);

  1985       VdbeComment((v, "# load subquery result"));

  1986       break;

  1987     }

  1988     case TK_IN: {

  1989       int addr;

  1990       char affinity;

  1991       int ckOffset = pParse->ckOffset;

  1992       sqlite3CodeSubselect(pParse, pExpr);

  1994       /* Figure out the affinity to use to create a key from the results

  1995       ** of the expression. affinityStr stores a static string suitable for

  1996       ** P3 of OP_MakeRecord.

  1997       */

  1998       affinity = comparisonAffinity(pExpr);

  2000       sqlite3VdbeAddOp(v, OP_Integer, 1, 0);

  2001       pParse->ckOffset = (ckOffset ? (ckOffset+1) : 0);

  2003       /* Code the <expr> from "<expr> IN (...)". The temporary table

  2004       ** pExpr->iTable contains the values that make up the (...) set.

  2005       */

  2006       sqlite3ExprCode(pParse, pExpr->pLeft);

  2007       addr = sqlite3VdbeCurrentAddr(v);

  2008       sqlite3VdbeAddOp(v, OP_NotNull, -1, addr+4);            /* addr + 0 */

  2009       sqlite3VdbeAddOp(v, OP_Pop, 2, 0);

  2010       sqlite3VdbeAddOp(v, OP_Null, 0, 0);

  2011       sqlite3VdbeAddOp(v, OP_Goto, 0, addr+7);

  2012       sqlite3VdbeOp3(v, OP_MakeRecord, 1, 0, &affinity, 1);   /* addr + 4 */

  2013       sqlite3VdbeAddOp(v, OP_Found, pExpr->iTable, addr+7);

  2014       sqlite3VdbeAddOp(v, OP_AddImm, -1, 0);                  /* addr + 6 */

  2016       break;

  2017     }

  2018 #endif

  2019     case TK_BETWEEN: {

  2020       Expr *pLeft = pExpr->pLeft;

  2021       struct ExprList_item *pLItem = pExpr->pList->a;

  2022       Expr *pRight = pLItem->pExpr;

  2023       sqlite3ExprCode(pParse, pLeft);

  2024       sqlite3VdbeAddOp(v, OP_Dup, 0, 0);

  2025       sqlite3ExprCode(pParse, pRight);

  2026       codeCompare(pParse, pLeft, pRight, OP_Ge, 0, 0);

  2027       sqlite3VdbeAddOp(v, OP_Pull, 1, 0);

  2028       pLItem++;

  2029       pRight = pLItem->pExpr;

  2030       sqlite3ExprCode(pParse, pRight);

  2031       codeCompare(pParse, pLeft, pRight, OP_Le, 0, 0);

  2032       sqlite3VdbeAddOp(v, OP_And, 0, 0);

  2033       break;

  2034     }

  2035     case TK_UPLUS: {

  2036       sqlite3ExprCode(pParse, pExpr->pLeft);

  2037       stackChng = 0;

  2038       break;

  2039     }

  2040     case TK_CASE: {

  2041       int expr_end_label;

  2042       int jumpInst;

  2043       int nExpr;

  2044       int i;

  2045       ExprList *pEList;

  2046       struct ExprList_item *aListelem;

  2048       assert(pExpr->pList);

  2049       assert((pExpr->pList->nExpr % 2) == 0);

  2050       assert(pExpr->pList->nExpr > 0);

  2051       pEList = pExpr->pList;

  2052       aListelem = pEList->a;

  2053       nExpr = pEList->nExpr;

  2054       expr_end_label = sqlite3VdbeMakeLabel(v);

  2055       if( pExpr->pLeft ){

  2056         sqlite3ExprCode(pParse, pExpr->pLeft);

  2057       }

  2058       for(i=0; i<nExpr; i=i+2){

  2059         sqlite3ExprCode(pParse, aListelem[i].pExpr);

  2060         if( pExpr->pLeft ){

  2061           sqlite3VdbeAddOp(v, OP_Dup, 1, 1);

  2062           jumpInst = codeCompare(pParse, pExpr->pLeft, aListelem[i].pExpr,

  2063                                  OP_Ne, 0, 1);

  2064           sqlite3VdbeAddOp(v, OP_Pop, 1, 0);

  2065         }else{

  2066           jumpInst = sqlite3VdbeAddOp(v, OP_IfNot, 1, 0);

  2067         }

  2068         sqlite3ExprCode(pParse, aListelem[i+1].pExpr);

  2069         sqlite3VdbeAddOp(v, OP_Goto, 0, expr_end_label);

  2070         sqlite3VdbeJumpHere(v, jumpInst);

  2071       }

  2072       if( pExpr->pLeft ){

  2073         sqlite3VdbeAddOp(v, OP_Pop, 1, 0);

  2074       }

  2075       if( pExpr->pRight ){

  2076         sqlite3ExprCode(pParse, pExpr->pRight);

  2077       }else{

  2078         sqlite3VdbeAddOp(v, OP_Null, 0, 0);

  2079       }

  2080       sqlite3VdbeResolveLabel(v, expr_end_label);

  2081       break;

  2082     }

  2083 #ifndef SQLITE_OMIT_TRIGGER

  2084     case TK_RAISE: {

  2085       if( !pParse->trigStack ){

  2086         sqlite3ErrorMsg(pParse,

  2087                        "RAISE() may only be used within a trigger-program");

  2088         return;

  2089       }

  2090       if( pExpr->iColumn!=OE_Ignore ){

  2091          assert( pExpr->iColumn==OE_Rollback ||

  2092                  pExpr->iColumn == OE_Abort ||

  2093                  pExpr->iColumn == OE_Fail );

  2094          sqlite3DequoteExpr(pParse->db, pExpr);

  2095          sqlite3VdbeOp3(v, OP_Halt, SQLITE_CONSTRAINT, pExpr->iColumn,

  2096                         (char*)pExpr->token.z, pExpr->token.n);

  2097       } else {

  2098          assert( pExpr->iColumn == OE_Ignore );

  2099          sqlite3VdbeAddOp(v, OP_ContextPop, 0, 0);

  2100          sqlite3VdbeAddOp(v, OP_Goto, 0, pParse->trigStack->ignoreJump);

  2101          VdbeComment((v, "# raise(IGNORE)"));

  2102       }

  2103       stackChng = 0;

  2104       break;

  2105     }

  2106 #endif

  2107   }

  2109   if( pParse->ckOffset ){

  2110     pParse->ckOffset += stackChng;

  2111     assert( pParse->ckOffset );

  2112   }

  2113 }

  2115 #ifndef SQLITE_OMIT_TRIGGER

  2116 /*

  2117 ** Generate code that evalutes the given expression and leaves the result

  2118 ** on the stack.  See also sqlite3ExprCode().

  2119 **

  2120 ** This routine might also cache the result and modify the pExpr tree

  2121 ** so that it will make use of the cached result on subsequent evaluations

  2122 ** rather than evaluate the whole expression again.  Trivial expressions are

  2123 ** not cached.  If the expression is cached, its result is stored in a

  2124 ** memory location.

  2125 */

  2126 void sqlite3ExprCodeAndCache(Parse *pParse, Expr *pExpr){

  2127   Vdbe *v = pParse->pVdbe;

  2128   int iMem;

  2129   int addr1, addr2;

  2130   if( v==0 ) return;

  2131   addr1 = sqlite3VdbeCurrentAddr(v);

  2132   sqlite3ExprCode(pParse, pExpr);

  2133   addr2 = sqlite3VdbeCurrentAddr(v);

  2134   if( addr2>addr1+1 || sqlite3VdbeGetOp(v, addr1)->opcode==OP_Function ){

  2135     iMem = pExpr->iTable = pParse->nMem++;

  2136     sqlite3VdbeAddOp(v, OP_MemStore, iMem, 0);

  2137     pExpr->op = TK_REGISTER;

  2138   }

  2139 }

  2140 #endif

  2142 /*

  2143 ** Generate code that pushes the value of every element of the given

  2144 ** expression list onto the stack.

  2145 **

  2146 ** Return the number of elements pushed onto the stack.

  2147 */

  2148 int sqlite3ExprCodeExprList(

  2149   Parse *pParse,     /* Parsing context */

  2150   ExprList *pList    /* The expression list to be coded */

  2151 ){

  2152   struct ExprList_item *pItem;

  2153   int i, n;

  2154   if( pList==0 ) return 0;

  2155   n = pList->nExpr;

  2156   for(pItem=pList->a, i=n; i>0; i--, pItem++){

  2157     sqlite3ExprCode(pParse, pItem->pExpr);

  2158   }

  2159   return n;

  2160 }

  2162 /*

  2163 ** Generate code for a boolean expression such that a jump is made

  2164 ** to the label "dest" if the expression is true but execution

  2165 ** continues straight thru if the expression is false.

  2166 **

  2167 ** If the expression evaluates to NULL (neither true nor false), then

  2168 ** take the jump if the jumpIfNull flag is true.

  2169 **

  2170 ** This code depends on the fact that certain token values (ex: TK_EQ)

  2171 ** are the same as opcode values (ex: OP_Eq) that implement the corresponding

  2172 ** operation.  Special comments in vdbe.c and the mkopcodeh.awk script in

  2173 ** the make process cause these values to align.  Assert()s in the code

  2174 ** below verify that the numbers are aligned correctly.

  2175 */

  2176 void sqlite3ExprIfTrue(Parse *pParse, Expr *pExpr, int dest, int jumpIfNull){

  2177   Vdbe *v = pParse->pVdbe;

  2178   int op = 0;

  2179   int ckOffset = pParse->ckOffset;

  2180   if( v==0 || pExpr==0 ) return;

  2181   op = pExpr->op;

  2182   switch( op ){

  2183     case TK_AND: {

  2184       int d2 = sqlite3VdbeMakeLabel(v);

  2185       sqlite3ExprIfFalse(pParse, pExpr->pLeft, d2, !jumpIfNull);

  2186       sqlite3ExprIfTrue(pParse, pExpr->pRight, dest, jumpIfNull);

  2187       sqlite3VdbeResolveLabel(v, d2);

  2188       break;

  2189     }

  2190     case TK_OR: {

  2191       sqlite3ExprIfTrue(pParse, pExpr->pLeft, dest, jumpIfNull);

  2192       sqlite3ExprIfTrue(pParse, pExpr->pRight, dest, jumpIfNull);

  2193       break;

  2194     }

  2195     case TK_NOT: {

  2196       sqlite3ExprIfFalse(pParse, pExpr->pLeft, dest, jumpIfNull);

  2197       break;

  2198     }

  2199     case TK_LT:

  2200     case TK_LE:

  2201     case TK_GT:

  2202     case TK_GE:

  2203     case TK_NE:

  2204     case TK_EQ: {

  2205       assert( TK_LT==OP_Lt );

  2206       assert( TK_LE==OP_Le );

  2207       assert( TK_GT==OP_Gt );

  2208       assert( TK_GE==OP_Ge );

  2209       assert( TK_EQ==OP_Eq );

  2210       assert( TK_NE==OP_Ne );

  2211       sqlite3ExprCode(pParse, pExpr->pLeft);

  2212       sqlite3ExprCode(pParse, pExpr->pRight);

  2213       codeCompare(pParse, pExpr->pLeft, pExpr->pRight, op, dest, jumpIfNull);

  2214       break;

  2215     }

  2216     case TK_ISNULL:

  2217     case TK_NOTNULL: {

  2218       assert( TK_ISNULL==OP_IsNull );

  2219       assert( TK_NOTNULL==OP_NotNull );

  2220       sqlite3ExprCode(pParse, pExpr->pLeft);

  2221       sqlite3VdbeAddOp(v, op, 1, dest);

  2222       break;

  2223     }

  2224     case TK_BETWEEN: {

  2225       /* The expression "x BETWEEN y AND z" is implemented as:

  2226       **

  2227       ** 1 IF (x < y) GOTO 3

  2228       ** 2 IF (x <= z) GOTO <dest>

  2229       ** 3 ...

  2230       */

  2231       int addr;

  2232       Expr *pLeft = pExpr->pLeft;

  2233       Expr *pRight = pExpr->pList->a[0].pExpr;

  2234       sqlite3ExprCode(pParse, pLeft);

  2235       sqlite3VdbeAddOp(v, OP_Dup, 0, 0);

  2236       sqlite3ExprCode(pParse, pRight);

  2237       addr = codeCompare(pParse, pLeft, pRight, OP_Lt, 0, !jumpIfNull);

  2239       pRight = pExpr->pList->a[1].pExpr;

  2240       sqlite3ExprCode(pParse, pRight);

  2241       codeCompare(pParse, pLeft, pRight, OP_Le, dest, jumpIfNull);

  2243       sqlite3VdbeAddOp(v, OP_Integer, 0, 0);

  2244       sqlite3VdbeJumpHere(v, addr);

  2245       sqlite3VdbeAddOp(v, OP_Pop, 1, 0);

  2246       break;

  2247     }

  2248     default: {

  2249       sqlite3ExprCode(pParse, pExpr);

  2250       sqlite3VdbeAddOp(v, OP_If, jumpIfNull, dest);

  2251       break;

  2252     }

  2253   }

  2254   pParse->ckOffset = ckOffset;

  2255 }

  2257 /*

  2258 ** Generate code for a boolean expression such that a jump is made

  2259 ** to the label "dest" if the expression is false but execution

  2260 ** continues straight thru if the expression is true.

  2261 **

  2262 ** If the expression evaluates to NULL (neither true nor false) then

  2263 ** jump if jumpIfNull is true or fall through if jumpIfNull is false.

  2264 */

  2265 void sqlite3ExprIfFalse(Parse *pParse, Expr *pExpr, int dest, int jumpIfNull){

  2266   Vdbe *v = pParse->pVdbe;

  2267   int op = 0;

  2268   int ckOffset = pParse->ckOffset;

  2269   if( v==0 || pExpr==0 ) return;

  2271   /* The value of pExpr->op and op are related as follows:

  2272   **

  2273   **       pExpr->op            op

  2274   **       ---------          ----------

  2275   **       TK_ISNULL          OP_NotNull

  2276   **       TK_NOTNULL         OP_IsNull

  2277   **       TK_NE              OP_Eq

  2278   **       TK_EQ              OP_Ne

  2279   **       TK_GT              OP_Le

  2280   **       TK_LE              OP_Gt

  2281   **       TK_GE              OP_Lt

  2282   **       TK_LT              OP_Ge

  2283   **

  2284   ** For other values of pExpr->op, op is undefined and unused.

  2285   ** The value of TK_ and OP_ constants are arranged such that we

  2286   ** can compute the mapping above using the following expression.

  2287   ** Assert()s verify that the computation is correct.

  2288   */

  2289   op = ((pExpr->op+(TK_ISNULL&1))^1)-(TK_ISNULL&1);

  2291   /* Verify correct alignment of TK_ and OP_ constants

  2292   */

  2293   assert( pExpr->op!=TK_ISNULL || op==OP_NotNull );

  2294   assert( pExpr->op!=TK_NOTNULL || op==OP_IsNull );

  2295   assert( pExpr->op!=TK_NE || op==OP_Eq );

  2296   assert( pExpr->op!=TK_EQ || op==OP_Ne );

  2297   assert( pExpr->op!=TK_LT || op==OP_Ge );

  2298   assert( pExpr->op!=TK_LE || op==OP_Gt );

  2299   assert( pExpr->op!=TK_GT || op==OP_Le );

  2300   assert( pExpr->op!=TK_GE || op==OP_Lt );

  2302   switch( pExpr->op ){

  2303     case TK_AND: {

  2304       sqlite3ExprIfFalse(pParse, pExpr->pLeft, dest, jumpIfNull);

  2305       sqlite3ExprIfFalse(pParse, pExpr->pRight, dest, jumpIfNull);

  2306       break;

  2307     }

  2308     case TK_OR: {

  2309       int d2 = sqlite3VdbeMakeLabel(v);

  2310       sqlite3ExprIfTrue(pParse, pExpr->pLeft, d2, !jumpIfNull);

  2311       sqlite3ExprIfFalse(pParse, pExpr->pRight, dest, jumpIfNull);

  2312       sqlite3VdbeResolveLabel(v, d2);

  2313       break;

  2314     }

  2315     case TK_NOT: {

  2316       sqlite3ExprIfTrue(pParse, pExpr->pLeft, dest, jumpIfNull);

  2317       break;

  2318     }

  2319     case TK_LT:

  2320     case TK_LE:

  2321     case TK_GT:

  2322     case TK_GE:

  2323     case TK_NE:

  2324     case TK_EQ: {

  2325       sqlite3ExprCode(pParse, pExpr->pLeft);

  2326       sqlite3ExprCode(pParse, pExpr->pRight);

  2327       codeCompare(pParse, pExpr->pLeft, pExpr->pRight, op, dest, jumpIfNull);

  2328       break;

  2329     }

  2330     case TK_ISNULL:

  2331     case TK_NOTNULL: {

  2332       sqlite3ExprCode(pParse, pExpr->pLeft);

  2333       sqlite3VdbeAddOp(v, op, 1, dest);

  2334       break;

  2335     }

  2336     case TK_BETWEEN: {

  2337       /* The expression is "x BETWEEN y AND z". It is implemented as:

  2338       **

  2339       ** 1 IF (x >= y) GOTO 3

  2340       ** 2 GOTO <dest>

  2341       ** 3 IF (x > z) GOTO <dest>

  2342       */

  2343       int addr;

  2344       Expr *pLeft = pExpr->pLeft;

  2345       Expr *pRight = pExpr->pList->a[0].pExpr;

  2346       sqlite3ExprCode(pParse, pLeft);

  2347       sqlite3VdbeAddOp(v, OP_Dup, 0, 0);

  2348       sqlite3ExprCode(pParse, pRight);

  2349       addr = sqlite3VdbeCurrentAddr(v);

  2350       codeCompare(pParse, pLeft, pRight, OP_Ge, addr+3, !jumpIfNull);

  2352       sqlite3VdbeAddOp(v, OP_Pop, 1, 0);

  2353       sqlite3VdbeAddOp(v, OP_Goto, 0, dest);

  2354       pRight = pExpr->pList->a[1].pExpr;

  2355       sqlite3ExprCode(pParse, pRight);

  2356       codeCompare(pParse, pLeft, pRight, OP_Gt, dest, jumpIfNull);

  2357       break;

  2358     }

  2359     default: {

  2360       sqlite3ExprCode(pParse, pExpr);

  2361       sqlite3VdbeAddOp(v, OP_IfNot, jumpIfNull, dest);

  2362       break;

  2363     }

  2364   }

  2365   pParse->ckOffset = ckOffset;

  2366 }

  2368 /*

  2369 ** Do a deep comparison of two expression trees.  Return TRUE (non-zero)

  2370 ** if they are identical and return FALSE if they differ in any way.

  2371 **

  2372 ** Sometimes this routine will return FALSE even if the two expressions

  2373 ** really are equivalent.  If we cannot prove that the expressions are

  2374 ** identical, we return FALSE just to be safe.  So if this routine

  2375 ** returns false, then you do not really know for certain if the two

  2376 ** expressions are the same.  But if you get a TRUE return, then you

  2377 ** can be sure the expressions are the same.  In the places where

  2378 ** this routine is used, it does not hurt to get an extra FALSE - that

  2379 ** just might result in some slightly slower code.  But returning

  2380 ** an incorrect TRUE could lead to a malfunction.

  2381 */

  2382 int sqlite3ExprCompare(Expr *pA, Expr *pB){

  2383   int i;

  2384   if( pA==0||pB==0 ){

  2385     return pB==pA;

  2386   }

  2387   if( pA->op!=pB->op ) return 0;

  2388   if( (pA->flags & EP_Distinct)!=(pB->flags & EP_Distinct) ) return 0;

  2389   if( !sqlite3ExprCompare(pA->pLeft, pB->pLeft) ) return 0;

  2390   if( !sqlite3ExprCompare(pA->pRight, pB->pRight) ) return 0;

  2391   if( pA->pList ){

  2392     if( pB->pList==0 ) return 0;

  2393     if( pA->pList->nExpr!=pB->pList->nExpr ) return 0;

  2394     for(i=0; i<pA->pList->nExpr; i++){

  2395       if( !sqlite3ExprCompare(pA->pList->a[i].pExpr, pB->pList->a[i].pExpr) ){

  2396         return 0;

  2397       }

  2398     }

  2399   }else if( pB->pList ){

  2400     return 0;

  2401   }

  2402   if( pA->pSelect || pB->pSelect ) return 0;

  2403   if( pA->iTable!=pB->iTable || pA->iColumn!=pB->iColumn ) return 0;

  2404   if( pA->op!=TK_COLUMN && pA->token.z ){

  2405     if( pB->token.z==0 ) return 0;

  2406     if( pB->token.n!=pA->token.n ) return 0;

  2407     if( sqlite3StrNICmp((char*)pA->token.z,(char*)pB->token.z,pB->token.n)!=0 ){

  2408       return 0;

  2409     }

  2410   }

  2411   return 1;

  2412 }

  2415 /*

  2416 ** Add a new element to the pAggInfo->aCol[] array.  Return the index of

  2417 ** the new element.  Return a negative number if malloc fails.

  2418 */

  2419 static int addAggInfoColumn(sqlite3 *db, AggInfo *pInfo){

  2420   int i;

  2421   pInfo->aCol = sqlite3ArrayAllocate(

  2422        db,

  2423        pInfo->aCol,

  2424        sizeof(pInfo->aCol[0]),

  2425        3,

  2426        &pInfo->nColumn,

  2427        &pInfo->nColumnAlloc,

  2428        &i

  2429   );

  2430   return i;

  2431 }

  2433 /*

  2434 ** Add a new element to the pAggInfo->aFunc[] array.  Return the index of

  2435 ** the new element.  Return a negative number if malloc fails.

  2436 */

  2437 static int addAggInfoFunc(sqlite3 *db, AggInfo *pInfo){

  2438   int i;

  2439   pInfo->aFunc = sqlite3ArrayAllocate(

  2440        db,

  2441        pInfo->aFunc,

  2442        sizeof(pInfo->aFunc[0]),

  2443        3,

  2444        &pInfo->nFunc,

  2445        &pInfo->nFuncAlloc,

  2446        &i

  2447   );

  2448   return i;

  2449 }

  2451 /*

  2452 ** This is an xFunc for walkExprTree() used to implement

  2453 ** sqlite3ExprAnalyzeAggregates().  See sqlite3ExprAnalyzeAggregates

  2454 ** for additional information.

  2455 **

  2456 ** This routine analyzes the aggregate function at pExpr.

  2457 */

  2458 static int analyzeAggregate(void *pArg, Expr *pExpr){

  2459   int i;

  2460   NameContext *pNC = (NameContext *)pArg;

  2461   Parse *pParse = pNC->pParse;

  2462   SrcList *pSrcList = pNC->pSrcList;

  2463   AggInfo *pAggInfo = pNC->pAggInfo;

  2465   switch( pExpr->op ){

  2466     case TK_AGG_COLUMN:

  2467     case TK_COLUMN: {

  2468       /* Check to see if the column is in one of the tables in the FROM

  2469       ** clause of the aggregate query */

  2470       if( pSrcList ){

  2471         struct SrcList_item *pItem = pSrcList->a;

  2472         for(i=0; i<pSrcList->nSrc; i++, pItem++){

  2473           struct AggInfo_col *pCol;

  2474           if( pExpr->iTable==pItem->iCursor ){

  2475             /* If we reach this point, it means that pExpr refers to a table

  2476             ** that is in the FROM clause of the aggregate query.

  2477             **

  2478             ** Make an entry for the column in pAggInfo->aCol[] if there

  2479             ** is not an entry there already.

  2480             */

  2481             int k;

  2482             pCol = pAggInfo->aCol;

  2483             for(k=0; k<pAggInfo->nColumn; k++, pCol++){

  2484               if( pCol->iTable==pExpr->iTable &&

  2485                   pCol->iColumn==pExpr->iColumn ){

  2486                 break;

  2487               }

  2488             }

  2489             if( (k>=pAggInfo->nColumn)

  2490              && (k = addAggInfoColumn(pParse->db, pAggInfo))>=0

  2491             ){

  2492               pCol = &pAggInfo->aCol[k];

  2493               pCol->pTab = pExpr->pTab;

  2494               pCol->iTable = pExpr->iTable;

  2495               pCol->iColumn = pExpr->iColumn;

  2496               pCol->iMem = pParse->nMem++;

  2497               pCol->iSorterColumn = -1;

  2498               pCol->pExpr = pExpr;

  2499               if( pAggInfo->pGroupBy ){

  2500                 int j, n;

  2501                 ExprList *pGB = pAggInfo->pGroupBy;

  2502                 struct ExprList_item *pTerm = pGB->a;

  2503                 n = pGB->nExpr;

  2504                 for(j=0; j<n; j++, pTerm++){

  2505                   Expr *pE = pTerm->pExpr;

  2506                   if( pE->op==TK_COLUMN && pE->iTable==pExpr->iTable &&

  2507                       pE->iColumn==pExpr->iColumn ){

  2508                     pCol->iSorterColumn = j;

  2509                     break;

  2510                   }

  2511                 }

  2512               }

  2513               if( pCol->iSorterColumn<0 ){

  2514                 pCol->iSorterColumn = pAggInfo->nSortingColumn++;

  2515               }

  2516             }

  2517             /* There is now an entry for pExpr in pAggInfo->aCol[] (either

  2518             ** because it was there before or because we just created it).

  2519             ** Convert the pExpr to be a TK_AGG_COLUMN referring to that

  2520             ** pAggInfo->aCol[] entry.

  2521             */

  2522             pExpr->pAggInfo = pAggInfo;

  2523             pExpr->op = TK_AGG_COLUMN;

  2524             pExpr->iAgg = k;

  2525             break;

  2526           } /* endif pExpr->iTable==pItem->iCursor */

  2527         } /* end loop over pSrcList */

  2528       }

  2529       return 1;

  2530     }

  2531     case TK_AGG_FUNCTION: {

  2532       /* The pNC->nDepth==0 test causes aggregate functions in subqueries

  2533       ** to be ignored */

  2534       if( pNC->nDepth==0 ){

  2535         /* Check to see if pExpr is a duplicate of another aggregate

  2536         ** function that is already in the pAggInfo structure

  2537         */

  2538         struct AggInfo_func *pItem = pAggInfo->aFunc;

  2539         for(i=0; i<pAggInfo->nFunc; i++, pItem++){

  2540           if( sqlite3ExprCompare(pItem->pExpr, pExpr) ){

  2541             break;

  2542           }

  2543         }

  2544         if( i>=pAggInfo->nFunc ){

  2545           /* pExpr is original.  Make a new entry in pAggInfo->aFunc[]

  2546           */

  2547           u8 enc = ENC(pParse->db);

  2548           i = addAggInfoFunc(pParse->db, pAggInfo);

  2549           if( i>=0 ){

  2550             pItem = &pAggInfo->aFunc[i];

  2551             pItem->pExpr = pExpr;

  2552             pItem->iMem = pParse->nMem++;

  2553             pItem->pFunc = sqlite3FindFunction(pParse->db,

  2554                    (char*)pExpr->token.z, pExpr->token.n,

  2555                    pExpr->pList ? pExpr->pList->nExpr : 0, enc, 0);

  2556             if( pExpr->flags & EP_Distinct ){

  2557               pItem->iDistinct = pParse->nTab++;

  2558             }else{

  2559               pItem->iDistinct = -1;

  2560             }

  2561           }

  2562         }

  2563         /* Make pExpr point to the appropriate pAggInfo->aFunc[] entry

  2564         */

  2565         pExpr->iAgg = i;

  2566         pExpr->pAggInfo = pAggInfo;

  2567         return 1;

  2568       }

  2569     }

  2570   }

  2572   /* Recursively walk subqueries looking for TK_COLUMN nodes that need

  2573   ** to be changed to TK_AGG_COLUMN.  But increment nDepth so that

  2574   ** TK_AGG_FUNCTION nodes in subqueries will be unchanged.

  2575   */

  2576   if( pExpr->pSelect ){

  2577     pNC->nDepth++;

  2578     walkSelectExpr(pExpr->pSelect, analyzeAggregate, pNC);

  2579     pNC->nDepth--;

  2580   }

  2581   return 0;

  2582 }

  2584 /*

  2585 ** Analyze the given expression looking for aggregate functions and

  2586 ** for variables that need to be added to the pParse->aAgg[] array.

  2587 ** Make additional entries to the pParse->aAgg[] array as necessary.

  2588 **

  2589 ** This routine should only be called after the expression has been

  2590 ** analyzed by sqlite3ExprResolveNames().

  2591 **

  2592 ** If errors are seen, leave an error message in zErrMsg and return

  2593 ** the number of errors.

  2594 */

  2595 int sqlite3ExprAnalyzeAggregates(NameContext *pNC, Expr *pExpr){

  2596   int nErr = pNC->pParse->nErr;

  2597   walkExprTree(pExpr, analyzeAggregate, pNC);

  2598   return pNC->pParse->nErr - nErr;

  2599 }

  2601 /*

  2602 ** Call sqlite3ExprAnalyzeAggregates() for every expression in an

  2603 ** expression list.  Return the number of errors.

  2604 **

  2605 ** If an error is found, the analysis is cut short.

  2606 */

  2607 int sqlite3ExprAnalyzeAggList(NameContext *pNC, ExprList *pList){

  2608   struct ExprList_item *pItem;

  2609   int i;

  2610   int nErr = 0;

  2611   if( pList ){

  2612     for(pItem=pList->a, i=0; nErr==0 && i<pList->nExpr; i++, pItem++){

  2613       nErr += sqlite3ExprAnalyzeAggregates(pNC, pItem->pExpr);

  2614     }

  2615   }

  2616   return nErr;

  2617 }

author	Scott Ehlert <ds@alliedmods.net>
	Sun Mar 30 07:00:22 2008 +0000 (2008-03-30)
changeset 1952	b7aa2b626807
permissions	-rw-r--r--