Virtual table modules with a null xCreate method act as eponymous-only modules -

they cannot be used in a CREATE VIRTUAL TABLE statement.  Add the series.c
extension that implements a postgres-like generate_series virtual table to
demonstrate this capability.

FossilOrigin-Name: c58426dbd5ea8b8440ebcc1214f79fa63d658216

Makefile.in

@@ -420,6 +420,7 @@ TESTSRC += \
   $(TOP)/ext/misc/nextchar.c \
   $(TOP)/ext/misc/percentile.c \
   $(TOP)/ext/misc/regexp.c \
+  $(TOP)/ext/misc/series.c \
   $(TOP)/ext/misc/spellfix.c \
   $(TOP)/ext/misc/totype.c \
   $(TOP)/ext/misc/wholenumber.c

Makefile.msc

@@ -1086,6 +1086,7 @@ TESTEXT = \
   $(TOP)\ext\misc\nextchar.c \
   $(TOP)\ext\misc\percentile.c \
   $(TOP)\ext\misc\regexp.c \
+  $(TOP)\ext\misc\series.c \
   $(TOP)\ext\misc\spellfix.c \
   $(TOP)\ext\misc\totype.c \
   $(TOP)\ext\misc\wholenumber.c

ext/misc/series.c

@@ -0,0 +1,290 @@
+/*
+** 2015-08-18
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file implements a virtual table that tries to replicate the 
+** behavior of the generate_series() table-valued-function in Postgres.
+**
+** Example:
+**
+**     SELECT * FROM generate_series WHERE start=1 AND stop=9 AND step=2
+**
+** Results in:
+**
+**     1 3 5 7 9
+**
+*/
+#include "sqlite3ext.h"
+SQLITE_EXTENSION_INIT1
+#include <assert.h>
+#include <string.h>
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+
+
+/* A series cursor object */
+typedef struct series_cursor series_cursor;
+struct series_cursor {
+  sqlite3_vtab_cursor base;  /* Base class - must be first */
+  sqlite3_int64 iValue;      /* Current value */
+  sqlite3_int64 mnValue;     /* Mimimum value */
+  sqlite3_int64 mxValue;     /* Maximum value */
+  sqlite3_int64 iStep;       /* How much to increment on each step */
+};
+
+/* Methods for the series module */
+static int seriesConnect(
+  sqlite3 *db,
+  void *pAux,
+  int argc, const char *const*argv,
+  sqlite3_vtab **ppVtab,
+  char **pzErr
+){
+  sqlite3_vtab *pNew;
+  pNew = *ppVtab = sqlite3_malloc( sizeof(*pNew) );
+  if( pNew==0 ) return SQLITE_NOMEM;
+
+#define SERIES_COLUMN_VALUE 0
+#define SERIES_COLUMN_START 1
+#define SERIES_COLUMN_STOP  2
+#define SERIES_COLUMN_STEP  3
+
+  sqlite3_declare_vtab(db,
+     "CREATE TABLE x(value,start hidden,stop hidden,step hidden)");
+  memset(pNew, 0, sizeof(*pNew));
+  return SQLITE_OK;
+}
+
+static int seriesDisconnect(sqlite3_vtab *pVtab){
+  sqlite3_free(pVtab);
+  return SQLITE_OK;
+}
+
+/*
+** Open a new series cursor.
+*/
+static int seriesOpen(sqlite3_vtab *p, sqlite3_vtab_cursor **ppCursor){
+  series_cursor *pCur;
+  pCur = sqlite3_malloc( sizeof(*pCur) );
+  if( pCur==0 ) return SQLITE_NOMEM;
+  memset(pCur, 0, sizeof(*pCur));
+  *ppCursor = &pCur->base;
+  return SQLITE_OK;
+}
+
+/*
+** Close a series cursor.
+*/
+static int seriesClose(sqlite3_vtab_cursor *cur){
+  sqlite3_free(cur);
+  return SQLITE_OK;
+}
+
+
+/*
+** Advance a cursor to its next row of output
+*/
+static int seriesNext(sqlite3_vtab_cursor *cur){
+  series_cursor *pCur = (series_cursor*)cur;
+  pCur->iValue += pCur->iStep;
+  return SQLITE_OK;
+}
+
+/*
+** Return the value associated with a series.
+*/
+static int seriesColumn(
+  sqlite3_vtab_cursor *cur,
+  sqlite3_context *ctx,
+  int i
+){
+  series_cursor *pCur = (series_cursor*)cur;
+  sqlite3_int64 x;
+  switch( i ){
+    case 0:  x = pCur->iValue;  break;
+    case 1:  x = pCur->mnValue; break;
+    case 2:  x = pCur->mxValue; break;
+    case 3:  x = pCur->iStep;   break;
+  }
+  sqlite3_result_int64(ctx, x);
+  return SQLITE_OK;
+}
+
+/*
+** The rowid.
+*/
+static int seriesRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
+  series_cursor *pCur = (series_cursor*)cur;
+  *pRowid = pCur->iValue;
+  return SQLITE_OK;
+}
+
+/*
+** Return TRUE if the last row has been output.
+*/
+static int seriesEof(sqlite3_vtab_cursor *cur){
+  series_cursor *pCur = (series_cursor*)cur;
+  return pCur->iValue>pCur->mxValue;
+}
+
+/*
+** Called to "rewind" a cursor back to the beginning so that
+** it starts its output over again.  Always called at least once
+** prior to any seriesColumn, seriesRowid, or seriesEof call.
+**
+** idxNum is a bitmask showing which constraints are available:
+**
+**    1:    start=VALUE
+**    2:    stop=VALUE
+**    4:    step=VALUE
+**
+*/
+static int seriesFilter(
+  sqlite3_vtab_cursor *pVtabCursor, 
+  int idxNum, const char *idxStr,
+  int argc, sqlite3_value **argv
+){
+  series_cursor *pCur = (series_cursor *)pVtabCursor;
+  int i = 0;
+  if( idxNum & 1 ){
+    pCur->mnValue = sqlite3_value_int64(argv[i++]);
+  }else{
+    pCur->mnValue = 0;
+  }
+  pCur->iValue = pCur->mnValue;
+  if( idxNum & 2 ){
+    pCur->mxValue = sqlite3_value_int64(argv[i++]);
+  }else{
+    pCur->mxValue = 0xffffffff;
+  }
+  if( idxNum & 4 ){
+    pCur->iStep = sqlite3_value_int64(argv[i++]);
+  }else{
+    pCur->iStep = 1;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Search for terms of these forms:
+**
+**  (1)  start = $value
+**  (2)  stop = $value
+**  (4)  step = $value
+**
+** idxNum is an ORed combination of 1, 2,  4.
+*/
+static int seriesBestIndex(
+  sqlite3_vtab *tab,
+  sqlite3_index_info *pIdxInfo
+){
+  int i;
+  int idxNum = 0;
+  int startIdx = -1;
+  int stopIdx = -1;
+  int stepIdx = -1;
+  int nArg = 0;
+
+  const struct sqlite3_index_constraint *pConstraint;
+  pConstraint = pIdxInfo->aConstraint;
+  for(i=0; i<pIdxInfo->nConstraint; i++, pConstraint++){
+    if( pConstraint->usable==0 ) continue;
+    if( pConstraint->op!=SQLITE_INDEX_CONSTRAINT_EQ ) continue;
+    switch( pConstraint->iColumn ){
+      case SERIES_COLUMN_START:
+        startIdx = i;
+        idxNum |= 1;
+        break;
+      case SERIES_COLUMN_STOP:
+        stopIdx = i;
+        idxNum |= 2;
+        break;
+      case SERIES_COLUMN_STEP:
+        stepIdx = i;
+        idxNum |= 4;
+        break;
+    }
+  }
+  pIdxInfo->idxNum = idxNum;
+  if( startIdx>=0 ){
+    pIdxInfo->aConstraintUsage[startIdx].argvIndex = ++nArg;
+    pIdxInfo->aConstraintUsage[startIdx].omit = 1;
+  }
+  if( stopIdx>=0 ){
+    pIdxInfo->aConstraintUsage[stopIdx].argvIndex = ++nArg;
+    pIdxInfo->aConstraintUsage[stopIdx].omit = 1;
+  }
+  if( stepIdx>=0 ){
+    pIdxInfo->aConstraintUsage[stepIdx].argvIndex = ++nArg;
+    pIdxInfo->aConstraintUsage[stepIdx].omit = 1;
+  }
+  if( pIdxInfo->nOrderBy==1
+   && pIdxInfo->aOrderBy[0].desc==0
+  ){
+    pIdxInfo->orderByConsumed = 1;
+  }
+  if( (idxNum & 3)==3 ){
+    /* Both start= and stop= boundaries are available.  This is the 
+    ** the preferred case */
+    pIdxInfo->estimatedCost = (double)1;
+  }else{
+    /* If either boundary is missing, we have to generate a huge span
+    ** of numbers.  Make this case very expensive so that the query
+    ** planner will work hard to avoid it. */
+    pIdxInfo->estimatedCost = (double)2000000000;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** A virtual table module that provides read-only access to a
+** Tcl global variable namespace.
+*/
+static sqlite3_module seriesModule = {
+  0,                         /* iVersion */
+  0,                         /* xCreate */
+  seriesConnect,
+  seriesBestIndex,
+  seriesDisconnect, 
+  0,                         /* xDestroy */
+  seriesOpen,                /* xOpen - open a cursor */
+  seriesClose,               /* xClose - close a cursor */
+  seriesFilter,              /* xFilter - configure scan constraints */
+  seriesNext,                /* xNext - advance a cursor */
+  seriesEof,                 /* xEof - check for end of scan */
+  seriesColumn,              /* xColumn - read data */
+  seriesRowid,               /* xRowid - read data */
+  0,                         /* xUpdate */
+  0,                         /* xBegin */
+  0,                         /* xSync */
+  0,                         /* xCommit */
+  0,                         /* xRollback */
+  0,                         /* xFindMethod */
+  0,                         /* xRename */
+};
+
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+int sqlite3_series_init(
+  sqlite3 *db, 
+  char **pzErrMsg, 
+  const sqlite3_api_routines *pApi
+){
+  int rc = SQLITE_OK;
+  SQLITE_EXTENSION_INIT2(pApi);
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  rc = sqlite3_create_module(db, "generate_series", &seriesModule, 0);
+#endif
+  return rc;
+}

main.mk

@@ -300,6 +300,7 @@ TESTSRC += \
   $(TOP)/ext/misc/nextchar.c \
   $(TOP)/ext/misc/percentile.c \
   $(TOP)/ext/misc/regexp.c \
+  $(TOP)/ext/misc/series.c \
   $(TOP)/ext/misc/spellfix.c \
   $(TOP)/ext/misc/totype.c \
   $(TOP)/ext/misc/wholenumber.c \

manifest

@@ -1,9 +1,9 @@
-C Merge\schanges\sfrom\strunk.
+C Virtual\stable\smodules\swith\sa\snull\sxCreate\smethod\sact\sas\seponymous-only\smodules\s-\nthey\scannot\sbe\sused\sin\sa\sCREATE\sVIRTUAL\sTABLE\sstatement.\s\sAdd\sthe\sseries.c\nextension\sthat\simplements\sa\spostgres-like\sgenerate_series\svirtual\stable\sto\ndemonstrate\sthis\scapability.
-D 2015-08-19T12:52:51.679
+D 2015-08-19T13:54:20.227
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
-F Makefile.in 2fc9ca6bf5949d415801c007ed3004a4bdb7c380
+F Makefile.in 4f663b6b4954b9b1eb0e6f08387688a93b57542d
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
-F Makefile.msc 5f7861c62c41fe8e3205ef14b90ebed28fa21f1b
+F Makefile.msc cf63e11a5395cf887515ac7b78e2057dfe442fcd
 F Makefile.vxworks e1b65dea203f054e71653415bd8f96dcaed47858
 F README.md 8ecc12493ff9f820cdea6520a9016001cb2e59b7
 F VERSION ccfc4d1576dbfdeece0a4372a2e6a2e37d3e7975
@@ -196,6 +196,7 @@ F ext/misc/nextchar.c 35c8b8baacb96d92abbb34a83a997b797075b342
 F ext/misc/percentile.c bcbee3c061b884eccb80e21651daaae8e1e43c63
 F ext/misc/regexp.c af92cdaa5058fcec1451e49becc7ba44dba023dc
 F ext/misc/rot13.c 1ac6f95f99b575907b9b09c81a349114cf9be45a
+F ext/misc/series.c c2be7ee41963cd2fcc1d7a226f5348fbe5f4f657
 F ext/misc/showauth.c 732578f0fe4ce42d577e1c86dc89dd14a006ab52
 F ext/misc/spellfix.c 86998fb73aefb7b5dc346ba8a58912f312da4996
 F ext/misc/totype.c 4a167594e791abeed95e0a8db028822b5e8fe512
@@ -256,7 +257,7 @@ F ext/userauth/userauth.c 5fa3bdb492f481bbc1709fc83c91ebd13460c69e
 F install-sh 9d4de14ab9fb0facae2f48780b874848cbf2f895 x
 F ltmain.sh 3ff0879076df340d2e23ae905484d8c15d5fdea8
 F magic.txt 8273bf49ba3b0c8559cb2774495390c31fd61c60
-F main.mk 73167b34b0e67c0be32c1da2d988a376851c9ab1
+F main.mk 702135e71d4438ea38c64b22fd6545a0fd87425c
 F mkopcodec.awk c2ff431854d702cdd2d779c9c0d1f58fa16fa4ea
 F mkopcodeh.awk 0e7f04a8eb90f92259e47d80110e4e98d7ce337a
 F mkso.sh fd21c06b063bb16a5d25deea1752c2da6ac3ed83
@@ -345,7 +346,7 @@ F src/sqliteLimit.h 216557999cb45f2e3578ed53ebefe228d779cb46
 F src/status.c f266ad8a2892d659b74f0f50cb6a88b6e7c12179
 F src/table.c 51b46b2a62d1b3a959633d593b89bab5e2c9155e
 F src/tclsqlite.c d9439b6a910985b7fff43ba6756bcef00de22649
-F src/test1.c d339ae9b9baf9221c657c9628c9061d88bd831f6
+F src/test1.c c12ed85c22ac95f87f79de2ec9553334d115f71e
 F src/test2.c 577961fe48961b2f2e5c8b56ee50c3f459d3359d
 F src/test3.c 64d2afdd68feac1bb5e2ffb8226c8c639f798622
 F src/test4.c d168f83cc78d02e8d35567bb5630e40dcd85ac1e
@@ -407,7 +408,7 @@ F src/vdbeblob.c 4f2e8e075d238392df98c5e03a64342465b03f90
 F src/vdbemem.c ae38a0d35ae71cf604381a887c170466ba518090
 F src/vdbesort.c f5009e7a35e3065635d8918b9a31f498a499976b
 F src/vdbetrace.c 8befe829faff6d9e6f6e4dee5a7d3f85cc85f1a0
-F src/vtab.c fddb32423d824831fbc42b8358ffadc2437edd97
+F src/vtab.c 1e3405f78e9f248bdee6ef7a8903fadaa7222f9c
 F src/vxworks.h c18586c8edc1bddbc15c004fa16aeb1e1342b4fb
 F src/wal.c 6fb6b68969e4692593c2552c4e7bff5882de2cb8
 F src/wal.h df01efe09c5cb8c8e391ff1715cca294f89668a4
@@ -1030,6 +1031,7 @@ F test/superlock.test 1cde669f68d2dd37d6c9bd35eee1d95491ae3fc2
 F test/sync.test a34cd43e98b7fb84eabbf38f7ed8f7349b3f3d85
 F test/syscall.test d2fdaad713f103ac611fe7ef9b724c7b69f8149c
 F test/sysfault.test fa776e60bf46bdd3ae69f0b73e46ee3977a58ae6
+F test/tabfunc01.test 239e336a556c92c6f81431f4f144f16311184880
 F test/table.test 33bf0d1fd07f304582695184b8e6feb017303816
 F test/tableapi.test 2674633fa95d80da917571ebdd759a14d9819126
 F test/tableopts.test dba698ba97251017b7c80d738c198d39ab747930
@@ -1374,7 +1376,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh 48bd54594752d5be3337f12c72f28d2080cb630b
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P c1f43a7799a9298abea01b2f8531fc7cdadc4594 c573b0a1aa3ba509234f07520fa94d008bcbb330
+P dddd792dedf0c73ebe74b4ff8d303e6216c16b6a
-R 04d75ba2dfa13388a455ec59c68a148d
+R 5f16282689e1192bf9396f5e61d5d753
 U drh
-Z d53ae36484d8828c21b5f9a23ee68eb5
+Z 970ed95f4f43231f807975375b2847aa

manifest.uuid

@@ -1 +1 @@
-dddd792dedf0c73ebe74b4ff8d303e6216c16b6a
+c58426dbd5ea8b8440ebcc1214f79fa63d658216

src/test1.c

@@ -6380,6 +6380,7 @@ static int tclLoadStaticExtensionCmd(
   extern int sqlite3_nextchar_init(sqlite3*,char**,const sqlite3_api_routines*);
   extern int sqlite3_percentile_init(sqlite3*,char**,const sqlite3_api_routines*);
   extern int sqlite3_regexp_init(sqlite3*,char**,const sqlite3_api_routines*);
+  extern int sqlite3_series_init(sqlite3*,char**,const sqlite3_api_routines*);
   extern int sqlite3_spellfix_init(sqlite3*,char**,const sqlite3_api_routines*);
   extern int sqlite3_totype_init(sqlite3*,char**,const sqlite3_api_routines*);
   extern int sqlite3_wholenumber_init(sqlite3*,char**,const sqlite3_api_routines*);
@@ -6400,6 +6401,7 @@ static int tclLoadStaticExtensionCmd(
     { "nextchar",              sqlite3_nextchar_init             },
     { "percentile",            sqlite3_percentile_init           },
     { "regexp",                sqlite3_regexp_init               },
+    { "series",                sqlite3_series_init               },
     { "spellfix",              sqlite3_spellfix_init             },
     { "totype",                sqlite3_totype_init               },
     { "wholenumber",           sqlite3_wholenumber_init          },

src/vtab.c

@@ -699,7 +699,7 @@ int sqlite3VtabCallCreate(sqlite3 *db, int iDb, const char *zTab, char **pzErr){
   ** invoke it now. If the module has not been registered, return an 
   ** error. Otherwise, do nothing.
   */
-  if( !pMod ){
+  if( pMod==0 || pMod->pModule->xCreate==0 ){
     *pzErr = sqlite3MPrintf(db, "no such module: %s", zMod);
     rc = SQLITE_ERROR;
   }else{
@@ -1109,7 +1109,7 @@ int sqlite3VtabEponymousTableInit(Parse *pParse, Module *pMod){
   int rc;
   sqlite3 *db = pParse->db;
   if( pMod->pEpoTab ) return 1;
-  if( pModule->xCreate!=pModule->xConnect ) return 0;
+  if( pModule->xCreate!=0 && pModule->xCreate!=pModule->xConnect ) return 0;
   nName = sqlite3Strlen30(pMod->zName) + 1;
   pTab = sqlite3DbMallocZero(db, sizeof(Table) + nName);
   if( pTab==0 ) return 0;

test/tabfunc01.test

@@ -0,0 +1,36 @@
+# 2015-08-19
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# 
+# This file implements tests for table-valued-functions implemented using
+# eponymous virtual tables.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+set testprefix tabfunc01
+
+ifcapable !vtab {
+  finish_test
+  return
+}
+load_static_extension db series
+
+do_execsql_test tabfunc01-1.1 {
+  SELECT *, '|' FROM generate_series WHERE start=1 AND stop=9 AND step=2;
+} {1 | 3 | 5 | 7 | 9 |}
+do_execsql_test tabfunc01-1.2 {
+  SELECT *, '|' FROM generate_series LIMIT 5;
+} {0 | 1 | 2 | 3 | 4 |}
+do_catchsql_test tabfunc01-1.3 {
+  CREATE VIRTUAL TABLE t1 USING generate_series;
+} {}
+
+finish_test