More work on the implementation of cursors, but they are still not

functioning. (CVS 2142)

FossilOrigin-Name: 8b61d1ae1ca469b80f2b344d550c3b363448b193

11 files changed, 159 insertions, 47 deletions

diff --git a/manifest b/manifest
index 6aae0d09e..258636050 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Add\sinitial\sinfrastructure\sfor\scursors.\s\sIn\swhere.c,\soptimize\sout\sclauses\nof\sthe\sform\s"ORDER\sBY\srowid"\sif\sa\stable\sscan\sis\sbeing\sperformed.\s\sDo\sa\nreverse\stable\sscan\sif\s"ORDER\sBY\srowid\sDESC"\sis\spresent.\s(CVS\s2141)
-D 2004-11-22T19:12:20
+C More\swork\son\sthe\simplementation\sof\scursors,\sbut\sthey\sare\sstill\snot\nfunctioning.\s(CVS\s2142)
+D 2004-11-23T01:47:30
 F Makefile.in 8291610f5839939a5fbff4dbbf85adb0fe1ac37f
 F Makefile.linux-gcc a9e5a0d309fa7c38e7c14d3ecf7690879d3a5457
 F README a01693e454a00cc117967e3f9fdab2d4d52e9bc1
@@ -32,10 +32,10 @@ F src/auth.c 3b81f2a42f48a62c2c9c9b0eda31a157c681edea
 F src/btree.c 05fe410ebbcbac72b66bc3aeeadf7e5588b0699e
 F src/btree.h 861e40b759a195ba63819740e484390012cf81ab
 F src/build.c b62389de594d0b413068d6e067794249a1f1d209
-F src/cursor.c dddc11922f583645318c9446d0d1920d0bc940cd
+F src/cursor.c f883813759742068890b1f699335872bfa8fdf41
 F src/date.c 65536e7ea04fdde6e0551264fca15966966e171f
-F src/delete.c cf185995e20a61c0fecc2a9a9a3b19bd18bd05b3
-F src/expr.c b985b42a3bce753040ab3415669d8a39b0538e5f
+F src/delete.c 9083377a4c5b152b4466021592f32e3e8a3819e3
+F src/expr.c 7987e5f50c189d4c2550f247f8039c06ea272345
 F src/func.c b668e5ad043176049454c95a6a780367a0e8f6bb
 F src/hash.c a97721a55440b7bea31ffe471bb2f6b4123cddd5
 F src/hash.h 1b0c445e1c89ff2aaad9b4605ba61375af001e84
@@ -59,10 +59,10 @@ F src/parse.y ceba179b9703657180963568f54b0e75f33e36e1
 F src/pragma.c d6406e12c9eac353b3a026b50d41e4fd561afcc2
 F src/printf.c 3d20b21cfecadacecac3fb7274e746cb81d3d357
 F src/random.c eff68e3f257e05e81eae6c4d50a51eb88beb4ff3
-F src/select.c b00478f33d6a9beb56f85b5d6b2e7325793c0bdf
+F src/select.c 36cc9da999596578566e167d310e99f2005a7f03
 F src/shell.c e8f4f486cbf6e60d81173146ac8a6522c930fa51
 F src/sqlite.h.in 6d0e82c24ef3f84a10b468119f3943a5dfc806c7
-F src/sqliteInt.h f783c2793ca02b1e8bee587f526932a43da14173
+F src/sqliteInt.h 1dc643cf84f1d83bd45e314f724bb824ee24c000
 F src/table.c 25b3ff2b39b7d87e8d4a5da0713d68dfc06cbee9
 F src/tclsqlite.c 7f1a1a678140e6901c8954590ca2aabe50b48f71
 F src/test1.c b7d94c54e58f95452387a5cabdf98b2be8059f29
@@ -72,17 +72,17 @@ F src/test4.c 7c6b9fc33dd1f3f93c7f1ee6e5e6d016afa6c1df
 F src/test5.c 64f08b2a50ef371a1bd68ff206829e7b1b9997f5
 F src/tokenize.c 2ad3d1ae1a0a70746db0b31a0a74f58050a3c39a
 F src/trigger.c 0c91b56182560263733e4b035acdb939bd1cf0e2
-F src/update.c 24a605a4250fe4a0b173bedd7132d1892ad27090
+F src/update.c d79d1936c5603b3ce2ee22557618b6baad67efba
 F src/utf.c e45ce11be6922408cd381561721f6cca7d3b992a
 F src/util.c 4a8db4e97a3cfda12ad8dda3e77dd2d00ad1de5e
 F src/vacuum.c 705256e1111521fa04f0029de7f1667bc131d015
-F src/vdbe.c ba3a920731d43bcf2497d558238400369008531a
+F src/vdbe.c b6caad985b7804b8158ab01b2021f1890570b7f3
 F src/vdbe.h 067ca8d6750ba4f69a50284765e5883dee860181
 F src/vdbeInt.h 6017100adff362b8dfa37a69e3f1431f084bfa5b
 F src/vdbeapi.c 74be7f96c0a1ac275661f8b32276ac521d9ce37c
 F src/vdbeaux.c dc06bbb8511d07f8d45ed2ea760f35f0736a690c
 F src/vdbemem.c 5876c8abf4374fef671f4fd8dc333ef3fc95a2f0
-F src/where.c be486196af29c4be8cc49275bc483a8af4cb8dcd
+F src/where.c f9d3b6f2243a0eb9065fa4c465fe0831a64b7db7
 F test/all.test 929bfa932b55e75c96fe2203f7650ba451c1862c
 F test/alter.test 95c57a4f461fa81293e0dccef7f83889aadb169a
 F test/attach.test a71117bab079c8a3a955e2d0270a76f9cb445935
@@ -115,7 +115,7 @@ F test/conflict.test c5b849b01cfbe0a4f63a90cba6f68e2fe3a75f87
 F test/corrupt.test 0080ddcece23e8ba47c44608c4fb73fd4d1d8ce2
 F test/crash.test 48b481769dd0ead25b0dfc0150853bfa39a3b65c
 F test/crashtest1.c 09c1c7d728ccf4feb9e481671e29dda5669bbcc2
-F test/cursor.test 376eabf81c727e15debc72d255d2c2624b9076c7
+F test/cursor.test d7c65ea0fc4e321e12fbcf5c7f3e2211ef45379b
 F test/date.test dda578ec1857837156bd8b32f8e09d81d7d7881c
 F test/delete.test fc29491f6a7ac899ce29f4549a104809e245d9a6
 F test/delete2.test e382b6a97787197eb8b93dd4ccd37797c3725ea3
@@ -261,7 +261,7 @@ F www/tclsqlite.tcl 560ecd6a916b320e59f2917317398f3d59b7cc25
 F www/vdbe.tcl 095f106d93875c94b47367384ebc870517431618
 F www/version3.tcl 092a01f5ef430d2c4acc0ae558d74c4bb89638a0
 F www/whentouse.tcl fdacb0ba2d39831e8a6240d05a490026ad4c4e4c
-P 3d2536c479c943b3a55047898068625f91c872ae
-R 72745c2cddac7210800e29c25c7bccd9
+P fc8c1393c86017a816beb52725b68af3b973f979
+R 98af4fe305ebafc3241be9d01cb582a6
 U drh
-Z a1c5d9d0383eefbb16dbdfab1a5f6edc
+Z 5a67f7855a17ccbeb24c26f03275c455
diff --git a/manifest.uuid b/manifest.uuid
index 1b26bb4bd..a7b2ef862 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-fc8c1393c86017a816beb52725b68af3b973f979
\ No newline at end of file
+8b61d1ae1ca469b80f2b344d550c3b363448b193
\ No newline at end of file
diff --git a/src/cursor.c b/src/cursor.c
index 061fcb699..6bd6f6cd7 100644
--- a/src/cursor.c
+++ b/src/cursor.c
@@ -21,7 +21,7 @@
 ** cursors, they are really very different things.  It is worth your while
 ** to fully understand the difference.
 **
-** @(#) $Id: cursor.c,v 1.1 2004/11/22 19:12:20 drh Exp $
+** @(#) $Id: cursor.c,v 1.2 2004/11/23 01:47:30 drh Exp $
 */
 #ifndef SQLITE_OMIT_CURSOR
 #include "sqliteInt.h"
@@ -86,13 +86,16 @@ void sqlite3CursorCreate(Parse *pParse, Token *pName, Select *pSelect){
   }
   db->apSqlCursor[i] = pNew = sqliteMallocRaw( sizeof(*pNew) + pName->n + 1 );
   if( pNew==0 ) goto end_create_cursor;
+  pNew->idx = i;
   pNew->zName = (char*)&pNew[1];
   memcpy(pNew->zName, pName->z, pName->n);
   pNew->zName[pName->n] = 0;
   pNew->pSelect = sqlite3SelectDup(pSelect);
-  pNew->nPtr = 0;
-  pNew->aPtr = 0;
-  pNew->idx = i;
+  pNew->nPtr = 2;
+  pNew->aPtr = sqliteMalloc( sizeof(Mem)*2 );
+  for(i=0; i<2; i++){
+    pNew->aPtr[i].flags = MEM_Null;
+  }
 
 end_create_cursor:
   sqlite3SelectDelete(pSelect);
@@ -118,6 +121,26 @@ void sqlite3CursorClose(Parse *pParse, Token *pName){
 }
 
 /*
+** Reverse the direction the ORDER BY clause on the SELECT statement.
+*/
+static void reverseSortOrder(Select *p){
+  if( p->pOrderBy==0 ){
+    /* If there no ORDER BY clause, add a new one that is "rowid DESC" */
+    static const Token rowid = { "ROWID", 0, 5 };
+    Expr *pExpr = sqlite3Expr(TK_ID, 0, 0, &rowid);
+    ExprList *pList = sqlite3ExprListAppend(0, pExpr, 0);
+    if( pList )  pList->a[0].sortOrder = SQLITE_SO_DESC;
+    p->pOrderBy = pList;
+  }else{
+    int i;
+    ExprList *pList = p->pOrderBy;
+    for(i=0; i<pList->nExpr; i++){
+      pList->a[i].sortOrder = !pList->a[i].sortOrder;
+    }
+  }
+}
+
+/*
 ** The parser calls this routine when it sees a complete FETCH statement.
 ** This routine generates code to implement the FETCH.
 **
@@ -142,26 +165,73 @@ void sqlite3Fetch(Parse *pParse, Token *pName, IdList *pInto){
   pCopy->pFetch = &sFetch;
   switch( pParse->fetchDir ){
     case TK_FIRST: {
+      sFetch.isBackwards = 0;
+      sFetch.doRewind = 1;
+      pCopy->nLimit = pParse->dirArg1;
+      pCopy->nOffset = 0;
       break;
     }
     case TK_LAST: {
+      reverseSortOrder(pCopy);
+      sFetch.isBackwards = 1;
+      sFetch.doRewind = 1;
+      pCopy->nLimit = pParse->dirArg1;
+      pCopy->nOffset = 0;
       break;
     }
     case TK_NEXT: {
+      sFetch.isBackwards = 0;
+      sFetch.doRewind = 0;
+      pCopy->nLimit = pParse->dirArg1;
+      pCopy->nOffset = 0;
       break;
     }
     case TK_PRIOR: {
+      reverseSortOrder(pCopy);
+      sFetch.isBackwards = 1;
+      sFetch.doRewind = 0;
+      pCopy->nLimit = pParse->dirArg1;
+      pCopy->nOffset = 0;
       break;
     }
     case TK_ABSOLUTE: {
+      sFetch.isBackwards = 0;
+      sFetch.doRewind = 1;
+      pCopy->nLimit = pParse->dirArg1;
+      pCopy->nOffset = pParse->dirArg2;
       break;
     }
     default: {
       assert( pParse->fetchDir==TK_RELATIVE );
+      if( pParse->dirArg2>=0 ){
+        /* The index parameter is positive.  Move forward from the current
+        ** location */
+        sFetch.isBackwards = 0;
+        sFetch.doRewind = 0;
+        pCopy->nLimit = pParse->dirArg1;
+        pCopy->nOffset = pParse->dirArg2;
+      }else{
+        /* The index is negative.  We have to code two separate SELECTs.
+        ** The first one seeks to the no position and the second one does
+        ** the query.
+        */
+        Select *pSeek = sqlite3SelectDup(pCopy);
+        reverseSortOrder(pSeek);
+        sFetch.isBackwards = 1;
+        sFetch.doRewind = 0;
+        pSeek->nLimit = pParse->dirArg2;
+        pSeek->pFetch = &sFetch;
+        sqlite3Select(pParse, pSeek, SRT_Discard, 0, 0, 0, 0, 0);
+        sFetch.isBackwards = 0;
+        sFetch.doRewind = 0;
+        pCopy->nLimit = pParse->dirArg1;
+        pCopy->nOffset = 0;
+      }
       break;
     }
   }
   sqlite3Select(pParse, pCopy, SRT_Callback, 0, 0, 0, 0, 0);
+
 end_fetch:
   sqlite3IdListDelete(pInto);
 }
diff --git a/src/delete.c b/src/delete.c
index 4887d6984..a0d30ea9d 100644
--- a/src/delete.c
+++ b/src/delete.c
@@ -12,7 +12,7 @@
 ** This file contains C code routines that are called by the parser
 ** to handle DELETE FROM statements.
 **
-** $Id: delete.c,v 1.90 2004/11/22 10:02:10 danielk1977 Exp $
+** $Id: delete.c,v 1.91 2004/11/23 01:47:30 drh Exp $
 */
 #include "sqliteInt.h"
 
@@ -229,7 +229,7 @@ void sqlite3DeleteFrom(
 
     /* Begin the database scan
     */
-    pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 1, 0);
+    pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 1, 0, 0);
     if( pWInfo==0 ) goto delete_from_cleanup;
 
     /* Remember the key of every item to be deleted.
diff --git a/src/expr.c b/src/expr.c
index 03fd866bd..de96ada74 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -12,7 +12,7 @@
 ** This file contains routines used for analyzing expressions and
 ** for generating VDBE code that evaluates expressions in SQLite.
 **
-** $Id: expr.c,v 1.173 2004/11/22 19:12:20 drh Exp $
+** $Id: expr.c,v 1.174 2004/11/23 01:47:30 drh Exp $
 */
 #include "sqliteInt.h"
 #include <ctype.h>
@@ -179,7 +179,7 @@ static int codeCompare(
 ** for this node is obtained from sqliteMalloc().  The calling function
 ** is responsible for making sure the node eventually gets freed.
 */
-Expr *sqlite3Expr(int op, Expr *pLeft, Expr *pRight, Token *pToken){
+Expr *sqlite3Expr(int op, Expr *pLeft, Expr *pRight, const Token *pToken){
   Expr *pNew;
   pNew = sqliteMalloc( sizeof(Expr) );
   if( pNew==0 ){
diff --git a/src/select.c b/src/select.c
index d17c26960..d16f43d23 100644
--- a/src/select.c
+++ b/src/select.c
@@ -12,7 +12,7 @@
 ** This file contains C code routines that are called by the parser
 ** to handle SELECT statements in SQLite.
 **
-** $Id: select.c,v 1.216 2004/11/22 19:12:21 drh Exp $
+** $Id: select.c,v 1.217 2004/11/23 01:47:30 drh Exp $
 */
 #include "sqliteInt.h"
 
@@ -2547,16 +2547,8 @@ int sqlite3Select(
 
   /* Begin the database scan
   */
-#if 0 /* ndef SQLITE_OMIT_CURSOR */
-  if( p->pFetch ){
-    pWInfo = sqlite3WhereBeginFetch(pParse, pTabList, pWhere,
-                                    pOrderby, p->pFetch);
-  }else
-#endif
-  {
-    pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0,
-                               pGroupBy ? 0 : &pOrderBy);
-  }
+  pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0,
+                             pGroupBy ? 0 : &pOrderBy, p->pFetch);
   if( pWInfo==0 ) goto select_end;
 
   /* Use the standard inner loop if we are not dealing with
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 0616d05a3..43f9afa1f 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -11,7 +11,7 @@
 *************************************************************************
 ** Internal interface definitions for SQLite.
 **
-** @(#) $Id: sqliteInt.h,v 1.343 2004/11/22 19:12:21 drh Exp $
+** @(#) $Id: sqliteInt.h,v 1.344 2004/11/23 01:47:30 drh Exp $
 */
 #ifndef _SQLITEINT_H_
 #define _SQLITEINT_H_
@@ -1281,7 +1281,7 @@ void sqlite3Dequote(char*);
 int sqlite3KeywordCode(const char*, int);
 int sqlite3RunParser(Parse*, const char*, char **);
 void sqlite3FinishCoding(Parse*);
-Expr *sqlite3Expr(int, Expr*, Expr*, Token*);
+Expr *sqlite3Expr(int, Expr*, Expr*, const Token*);
 Expr *sqlite3RegisterExpr(Parse*,Token*);
 Expr *sqlite3ExprAnd(Expr*, Expr*);
 void sqlite3ExprSpan(Expr*,Token*,Token*);
@@ -1341,7 +1341,7 @@ void sqlite3OpenTableForReading(Vdbe*, int iCur, Table*);
 void sqlite3OpenTable(Vdbe*, int iCur, Table*, int);
 void sqlite3DeleteFrom(Parse*, SrcList*, Expr*);
 void sqlite3Update(Parse*, SrcList*, ExprList*, Expr*, int);
-WhereInfo *sqlite3WhereBegin(Parse*, SrcList*, Expr*, int, ExprList**);
+WhereInfo *sqlite3WhereBegin(Parse*, SrcList*, Expr*, int, ExprList**, Fetch*);
 void sqlite3WhereEnd(WhereInfo*);
 void sqlite3ExprCode(Parse*, Expr*);
 int sqlite3ExprCodeExprList(Parse*, ExprList*);
diff --git a/src/update.c b/src/update.c
index 501ca6c3e..4dd040ee5 100644
--- a/src/update.c
+++ b/src/update.c
@@ -12,7 +12,7 @@
 ** This file contains C code routines that are called by the parser
 ** to handle UPDATE statements.
 **
-** $Id: update.c,v 1.96 2004/11/22 10:02:11 danielk1977 Exp $
+** $Id: update.c,v 1.97 2004/11/23 01:47:30 drh Exp $
 */
 #include "sqliteInt.h"
 
@@ -235,7 +235,7 @@ void sqlite3Update(
 
   /* Begin the database scan
   */
-  pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 1, 0);
+  pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 1, 0, 0);
   if( pWInfo==0 ) goto update_cleanup;
 
   /* Remember the index of every item to be updated.
diff --git a/src/vdbe.c b/src/vdbe.c
index 31ecea193..dc4963eaf 100644
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -43,7 +43,7 @@
 ** in this file for details.  If in doubt, do not deviate from existing
 ** commenting and indentation practices when changing or adding code.
 **
-** $Id: vdbe.c,v 1.430 2004/11/18 02:10:55 drh Exp $
+** $Id: vdbe.c,v 1.431 2004/11/23 01:47:30 drh Exp $
 */
 #include "sqliteInt.h"
 #include "os.h"
@@ -4433,6 +4433,56 @@ case OP_Vacuum: {
   break;
 }
 
+#ifndef SQLITE_OMIT_CURSOR
+/* Opcode: CursorStore P1 P2 *
+**
+** The implementation of SQL cursors (not to be confused with VDBE cursors
+** or B-tree cursors) stores information in the SQLite database connection
+** structure (the sqlite3* pointer) that identifies the row
+** in a table that an SQL cursor is pointing to.  This opcode is
+** used to store that information.  P1 is an index of an SQL cursor.
+** P2 is the index of a memory slot within that SQL cursor.  This opcode
+** pops the top of the stack and stores it in the SQL cursor.
+*/
+case OP_CursorStore: {
+  SqlCursor *pCursor;
+  assert( pTos>=p->aStack );
+  assert( pOp->p1>=0 && pOp->p1<db->nSqlCursor );
+  pCursor = db->apSqlCursor[pOp->p1];
+  assert( pCursor!=0 );
+  assert( pOp->p2>=0 && pOp->p2<2 );  
+  rc = sqlite3VdbeMemMove(&pCursor->aPtr[pOp->p1], pTos);
+  pTos--;
+  break;
+}
+
+/* Opcode: CursorLoad P1 P2 *
+**
+** The implementation of SQL cursors (not to be confused with VDBE cursors
+** or B-tree cursors) stores information in the SQLite database connection
+** structure (the sqlite3* pointer) that effectively records the current
+** location in a table that an SQL cursor is pointing to.  This opcode is
+** used to recover that information.  P1 is an index of an SQL cursor.
+** P2 is the index of a memory slot within that SQL cursor.  This opcode
+** pushes a new value onto the stack which is a copy of the information
+** obtained from entry P2 of cursor P1.
+*/
+case OP_CursorLoad: {
+  SqlCursor *pCursor;
+  int i = pOp->p1;
+  assert( pTos>=p->aStack );
+  assert( pOp->p1>=0 && pOp->p1<db->nSqlCursor );
+  pCursor = db->apSqlCursor[pOp->p1];
+  assert( pCursor!=0 );
+  assert( pOp->p2>=0 && pOp->p2<2 );  
+  pTos++;
+  sqlite3VdbeMemShallowCopy(pTos, &pCursor->aPtr[i], MEM_Ephem);
+  break;
+}
+#endif /* SQLITE_OMIT_CURSOR */
+
+
+
 /* An other opcode is illegal...
 */
 default: {
diff --git a/src/where.c b/src/where.c
index 97cf37d69..1e7073c2f 100644
--- a/src/where.c
+++ b/src/where.c
@@ -12,7 +12,7 @@
 ** This module contains C code that generates VDBE code used to process
 ** the WHERE clause of SQL statements.
 **
-** $Id: where.c,v 1.119 2004/11/22 19:12:21 drh Exp $
+** $Id: where.c,v 1.120 2004/11/23 01:47:31 drh Exp $
 */
 #include "sqliteInt.h"
 
@@ -498,17 +498,14 @@ static void codeEqualityTerm(
 **
 ** If the where clause loops cannot be arranged to provide the correct
 ** output order, then the *ppOrderBy is unchanged.
-**
-** If parameter iTabCur is non-negative, then it is a cursor already open
-** on table pTabList->aSrc[0]. Use this cursor instead of opening a new
-** one.
 */
 WhereInfo *sqlite3WhereBegin(
   Parse *pParse,        /* The parser context */
   SrcList *pTabList,    /* A list of all tables to be scanned */
   Expr *pWhere,         /* The WHERE clause */
   int pushKey,          /* If TRUE, leave the table key on the stack */
-  ExprList **ppOrderBy  /* An ORDER BY clause, or NULL */
+  ExprList **ppOrderBy, /* An ORDER BY clause, or NULL */
+  Fetch *pFetch         /* Initial location of cursors.  NULL otherwise */
 ){
   int i;                     /* Loop counter */
   WhereInfo *pWInfo;         /* Will become the return value of this function */
@@ -529,6 +526,9 @@ WhereInfo *sqlite3WhereBegin(
   */
   assert( pushKey==0 || pTabList->nSrc==1 );
 
+  /*
+  */
+
   /* Split the WHERE clause into separate subexpressions where each
   ** subexpression is separated by an AND operator.  If the aExpr[]
   ** array fills up, the last entry might point to an expression which
diff --git a/test/cursor.test b/test/cursor.test
index dcd83a2a4..815913e3b 100644
--- a/test/cursor.test
+++ b/test/cursor.test
@@ -11,7 +11,7 @@
 # This file implements regression tests for SQLite library.  The
 # focus of this script is DECLARE...CURSOR functionality
 #
-# $Id: cursor.test,v 1.1 2004/11/22 19:12:21 drh Exp $
+# $Id: cursor.test,v 1.2 2004/11/23 01:47:31 drh Exp $
 #
 
 set testdir [file dirname $argv0]