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Overview
Comment: | Optimization to the ExprList object to make it slightly smaller and faster. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA3-256: |
4da49a95c0f07ed7790169e8833c3e2d |
User & Date: | drh 2017-09-15 15:17:48.630 |
References
2017-09-17
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19:45 | Do not make the assumption (as check-in [4da49a95c0f07] incorrectly did) that the ExprList returned by sqlite3ExprListDup() would never be passed into sqlite3ExprListAppend(). Include a new test case that shows this sometimes does happen. (check-in: 29227d00a9 user: drh tags: trunk) | |
Context
2017-09-15
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15:38 | Improved the header-comment documentation on sqlite3ExprCodeExprList(). No changes to code. (check-in: 5dc3ecb5f6 user: drh tags: trunk) | |
15:17 | Optimization to the ExprList object to make it slightly smaller and faster. (check-in: 4da49a95c0 user: drh tags: trunk) | |
14:36 | Fix a harmless comment typo. No changes to code. (check-in: f7f0bf1da0 user: drh tags: trunk) | |
Changes
Changes to src/expr.c.
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1301 1302 1303 1304 1305 1306 1307 | int i; Expr *pPriorSelectCol = 0; assert( db!=0 ); if( p==0 ) return 0; pNew = sqlite3DbMallocRawNN(db, sizeof(*pNew)+sizeof(pNew->a[0])*(p->nExpr-1) ); if( pNew==0 ) return 0; | | > > > > | 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 | int i; Expr *pPriorSelectCol = 0; assert( db!=0 ); if( p==0 ) return 0; pNew = sqlite3DbMallocRawNN(db, sizeof(*pNew)+sizeof(pNew->a[0])*(p->nExpr-1) ); if( pNew==0 ) return 0; pNew->nExpr = p->nExpr; /* After being duplicated, the ExprList may not be expanded again using ** Append() because Append() assumes that the number of slots in ** ExprList.a[] is a power of 2 */ VVA_ONLY( pNew->bFixedSize = 1 ); pItem = pNew->a; pOldItem = p->a; for(i=0; i<p->nExpr; i++, pItem++, pOldItem++){ Expr *pOldExpr = pOldItem->pExpr; Expr *pNewExpr; pItem->pExpr = sqlite3ExprDup(db, pOldExpr, flags); if( pOldExpr |
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1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 | #endif /* ** Add a new element to the end of an expression list. If pList is ** initially NULL, then create a new expression list. ** ** If a memory allocation error occurs, the entire list is freed and ** NULL is returned. If non-NULL is returned, then it is guaranteed ** that the new entry was successfully appended. */ ExprList *sqlite3ExprListAppend( Parse *pParse, /* Parsing context */ ExprList *pList, /* List to which to append. Might be NULL */ Expr *pExpr /* Expression to be appended. Might be NULL */ ){ struct ExprList_item *pItem; sqlite3 *db = pParse->db; assert( db!=0 ); if( pList==0 ){ pList = sqlite3DbMallocRawNN(db, sizeof(ExprList) ); if( pList==0 ){ goto no_mem; } pList->nExpr = 0; | > > > > > > > > | | | < | 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 | #endif /* ** Add a new element to the end of an expression list. If pList is ** initially NULL, then create a new expression list. ** ** The pList argument must be either NULL or a pointer to an ExprList ** obtained from a prior call to sqlite3ExprListAppend(). This routine ** may not be used with an ExprList obtained from sqlite3ExprListDup(). ** Reason: This routine assumes that the number of slots in pList->a[] ** is a power of two. That is true for sqlite3ExprListAppend() returns ** but is not necessarily true from the return value of sqlite3ExprListDup(). ** ** If a memory allocation error occurs, the entire list is freed and ** NULL is returned. If non-NULL is returned, then it is guaranteed ** that the new entry was successfully appended. */ ExprList *sqlite3ExprListAppend( Parse *pParse, /* Parsing context */ ExprList *pList, /* List to which to append. Might be NULL */ Expr *pExpr /* Expression to be appended. Might be NULL */ ){ struct ExprList_item *pItem; sqlite3 *db = pParse->db; assert( db!=0 ); assert( pList==0 || pList->bFixedSize==0 ); if( pList==0 ){ pList = sqlite3DbMallocRawNN(db, sizeof(ExprList) ); if( pList==0 ){ goto no_mem; } pList->nExpr = 0; VVA_ONLY( pList->bFixedSize = 0 ); }else if( (pList->nExpr & (pList->nExpr-1))==0 ){ ExprList *pNew; pNew = sqlite3DbRealloc(db, pList, sizeof(*pList)+(2*pList->nExpr - 1)*sizeof(pList->a[0])); if( pNew==0 ){ goto no_mem; } pList = pNew; } pItem = &pList->a[pList->nExpr++]; assert( offsetof(struct ExprList_item,zName)==sizeof(pItem->pExpr) ); assert( offsetof(struct ExprList_item,pExpr)==0 ); memset(&pItem->zName,0,sizeof(*pItem)-offsetof(struct ExprList_item,zName)); pItem->pExpr = pExpr; return pList; |
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Changes to src/sqliteInt.h.
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2464 2465 2466 2467 2468 2469 2470 | ** column expression as it exists in a SELECT statement. However, if ** the bSpanIsTab flag is set, then zSpan is overloaded to mean the name ** of the result column in the form: DATABASE.TABLE.COLUMN. This later ** form is used for name resolution with nested FROM clauses. */ struct ExprList { int nExpr; /* Number of expressions on the list */ | > | > | 2464 2465 2466 2467 2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478 2479 2480 | ** column expression as it exists in a SELECT statement. However, if ** the bSpanIsTab flag is set, then zSpan is overloaded to mean the name ** of the result column in the form: DATABASE.TABLE.COLUMN. This later ** form is used for name resolution with nested FROM clauses. */ struct ExprList { int nExpr; /* Number of expressions on the list */ #ifdef SQLITE_DEBUG u8 bFixedSize; /* May not be expanded using sqlite3ExprListAppend() */ #endif struct ExprList_item { /* For each expression in the list */ Expr *pExpr; /* The parse tree for this expression */ char *zName; /* Token associated with this expression */ char *zSpan; /* Original text of the expression */ u8 sortOrder; /* 1 for DESC or 0 for ASC */ unsigned done :1; /* A flag to indicate when processing is finished */ unsigned bSpanIsTab :1; /* zSpan holds DB.TABLE.COLUMN */ |
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