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Add Go API for virtual tables 

See https://www.sqlite.org/vtab.html for more details.

This work was started from
https://github.com/gwenn/gosqlite/blob/master/vtab.{c,go} and adds:

- Porting the API to go-sqlite3 APIs.
- Support for >= Go 1.6 without requiring the `cgocheck` flag to be changed.
- Filling out the unfinished callback functions for the `Vtable` struct.
- A simple `Context` API layer for ease of use when adding modules.

Tests are included.
This commit is contained in:
Conor Branagan 2016-11-10 10:27:20 -05:00
parent 3439fd2096
commit bba480975b
5 changed files with 798 additions and 1 deletions
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103
context.go Normal file
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@ -0,0 +1,103 @@
// Copyright (C) 2014 Yasuhiro Matsumoto <mattn.jp@gmail.com>.
//
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
package sqlite3
/*
#ifndef USE_LIBSQLITE3
#include <sqlite3-binding.h>
#else
#include <sqlite3.h>
#endif
#include <stdlib.h>
// These wrappers are necessary because SQLITE_TRANSIENT
// is a pointer constant, and cgo doesn't translate them correctly.
static inline void my_result_text(sqlite3_context *ctx, char *p, int np) {
sqlite3_result_text(ctx, p, np, SQLITE_TRANSIENT);
}
static inline void my_result_blob(sqlite3_context *ctx, void *p, int np) {
sqlite3_result_blob(ctx, p, np, SQLITE_TRANSIENT);
}
*/
import "C"
import (
"math"
"reflect"
"unsafe"
)
const i64 = unsafe.Sizeof(int(0)) > 4
type ZeroBlobLength int32
type Context C.sqlite3_context
// ResultBool sets the result of an SQL function.
func (c *Context) ResultBool(b bool) {
if b {
c.ResultInt(1)
} else {
c.ResultInt(0)
}
}
// ResultBlob sets the result of an SQL function.
// See: sqlite3_result_blob, http://sqlite.org/c3ref/result_blob.html
func (c *Context) ResultBlob(b []byte) {
if i64 && len(b) > math.MaxInt32 {
C.sqlite3_result_error_toobig((*C.sqlite3_context)(c))
return
}
var p *byte
if len(b) > 0 {
p = &b[0]
}
C.my_result_blob((*C.sqlite3_context)(c), unsafe.Pointer(p), C.int(len(b)))
}
// ResultDouble sets the result of an SQL function.
// See: sqlite3_result_double, http://sqlite.org/c3ref/result_blob.html
func (c *Context) ResultDouble(d float64) {
C.sqlite3_result_double((*C.sqlite3_context)(c), C.double(d))
}
// ResultInt sets the result of an SQL function.
// See: sqlite3_result_int, http://sqlite.org/c3ref/result_blob.html
func (c *Context) ResultInt(i int) {
if i64 && (i > math.MaxInt32 || i < math.MinInt32) {
C.sqlite3_result_int64((*C.sqlite3_context)(c), C.sqlite3_int64(i))
} else {
C.sqlite3_result_int((*C.sqlite3_context)(c), C.int(i))
}
}
// ResultInt64 sets the result of an SQL function.
// See: sqlite3_result_int64, http://sqlite.org/c3ref/result_blob.html
func (c *Context) ResultInt64(i int64) {
C.sqlite3_result_int64((*C.sqlite3_context)(c), C.sqlite3_int64(i))
}
// ResultNull sets the result of an SQL function.
// See: sqlite3_result_null, http://sqlite.org/c3ref/result_blob.html
func (c *Context) ResultNull() {
C.sqlite3_result_null((*C.sqlite3_context)(c))
}
// ResultText sets the result of an SQL function.
// See: sqlite3_result_text, http://sqlite.org/c3ref/result_blob.html
func (c *Context) ResultText(s string) {
h := (*reflect.StringHeader)(unsafe.Pointer(&s))
cs, l := (*C.char)(unsafe.Pointer(h.Data)), C.int(h.Len)
C.my_result_text((*C.sqlite3_context)(c), cs, l)
}
// ResultZeroblob sets the result of an SQL function.
// See: sqlite3_result_zeroblob, http://sqlite.org/c3ref/result_blob.html
func (c *Context) ResultZeroblob(n ZeroBlobLength) {
C.sqlite3_result_zeroblob((*C.sqlite3_context)(c), C.int(n))
}

2
sqlite3.go
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@ -627,11 +627,11 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
// Close the connection.
func (c *SQLiteConn) Close() error {
deleteHandles(c)
rv := C.sqlite3_close_v2(c.db)
if rv != C.SQLITE_OK {
return c.lastError()
}
deleteHandles(c)
c.db = nil
runtime.SetFinalizer(c, nil)
return nil

182
vtable.c Normal file
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@ -0,0 +1,182 @@
// Copyright (C) 2014 Yasuhiro Matsumoto <mattn.jp@gmail.com>.
//
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
#ifndef USE_LIBSQLITE3
#include <sqlite3-binding.h>
#else
#include <sqlite3.h>
#endif
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include "_cgo_export.h"
typedef struct goVTab goVTab;
struct goVTab {
sqlite3_vtab base;
void *vTab;
};
static int cXInit(sqlite3 *db, void *pAux, int argc, const char *const*argv, sqlite3_vtab **ppVTab, char **pzErr, int isCreate) {
void *vTab = (void *)goMInit(db, pAux, argc, (char**)argv, pzErr, isCreate);
if (!vTab || *pzErr) {
return SQLITE_ERROR;
}
goVTab *pvTab = (goVTab *)sqlite3_malloc(sizeof(goVTab));
if (!pvTab) {
*pzErr = sqlite3_mprintf("%s", "Out of memory");
return SQLITE_NOMEM;
}
memset(pvTab, 0, sizeof(goVTab));
pvTab->vTab = vTab;
*ppVTab = (sqlite3_vtab *)pvTab;
*pzErr = 0;
return SQLITE_OK;
}
static inline int cXCreate(sqlite3 *db, void *pAux, int argc, const char *const*argv, sqlite3_vtab **ppVTab, char **pzErr) {
return cXInit(db, pAux, argc, argv, ppVTab, pzErr, 1);
}
static inline int cXConnect(sqlite3 *db, void *pAux, int argc, const char *const*argv, sqlite3_vtab **ppVTab, char **pzErr) {
return cXInit(db, pAux, argc, argv, ppVTab, pzErr, 0);
}
static inline int cXBestIndex(sqlite3_vtab *pVTab, sqlite3_index_info *info) {
char *pzErr = goVBestIndex(((goVTab*)pVTab)->vTab, info);
if (pzErr) {
if (pVTab->zErrMsg)
sqlite3_free(pVTab->zErrMsg);
pVTab->zErrMsg = pzErr;
return SQLITE_ERROR;
}
return SQLITE_OK;
}
static int cXRelease(sqlite3_vtab *pVTab, int isDestroy) {
char *pzErr = goVRelease(((goVTab*)pVTab)->vTab, isDestroy);
if (pzErr) {
if (pVTab->zErrMsg)
sqlite3_free(pVTab->zErrMsg);
pVTab->zErrMsg = pzErr;
return SQLITE_ERROR;
}
if (pVTab->zErrMsg)
sqlite3_free(pVTab->zErrMsg);
sqlite3_free(pVTab);
return SQLITE_OK;
}
static inline int cXDisconnect(sqlite3_vtab *pVTab) {
return cXRelease(pVTab, 0);
}
static inline int cXDestroy(sqlite3_vtab *pVTab) {
return cXRelease(pVTab, 1);
}
typedef struct goVTabCursor goVTabCursor;
struct goVTabCursor {
sqlite3_vtab_cursor base;
void *vTabCursor;
};
static int cXOpen(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor) {
void *vTabCursor = (void *)goVOpen(((goVTab*)pVTab)->vTab, &(pVTab->zErrMsg));
goVTabCursor *pCursor = (goVTabCursor *)sqlite3_malloc(sizeof(goVTabCursor));
if (!pCursor) {
return SQLITE_NOMEM;
}
memset(pCursor, 0, sizeof(goVTabCursor));
pCursor->vTabCursor = vTabCursor;
*ppCursor = (sqlite3_vtab_cursor *)pCursor;
return SQLITE_OK;
}
static int setErrMsg(sqlite3_vtab_cursor *pCursor, char *pzErr) {
if (pCursor->pVtab->zErrMsg)
sqlite3_free(pCursor->pVtab->zErrMsg);
pCursor->pVtab->zErrMsg = pzErr;
return SQLITE_ERROR;
}
static int cXClose(sqlite3_vtab_cursor *pCursor) {
char *pzErr = goVClose(((goVTabCursor*)pCursor)->vTabCursor);
if (pzErr) {
return setErrMsg(pCursor, pzErr);
}
sqlite3_free(pCursor);
return SQLITE_OK;
}
static int cXFilter(sqlite3_vtab_cursor *pCursor, int idxNum, const char *idxStr, int argc, sqlite3_value **argv) {
char *pzErr = goVFilter(((goVTabCursor*)pCursor)->vTabCursor, idxNum, (char*)idxStr, argc, argv);
if (pzErr) {
return setErrMsg(pCursor, pzErr);
}
return SQLITE_OK;
}
static int cXNext(sqlite3_vtab_cursor *pCursor) {
char *pzErr = goVNext(((goVTabCursor*)pCursor)->vTabCursor);
if (pzErr) {
return setErrMsg(pCursor, pzErr);
}
return SQLITE_OK;
}
static inline int cXEof(sqlite3_vtab_cursor *pCursor) {
return goVEof(((goVTabCursor*)pCursor)->vTabCursor);
}
static int cXColumn(sqlite3_vtab_cursor *pCursor, sqlite3_context *ctx, int i) {
char *pzErr = goVColumn(((goVTabCursor*)pCursor)->vTabCursor, ctx, i);
if (pzErr) {
return setErrMsg(pCursor, pzErr);
}
return SQLITE_OK;
}
static int cXRowid(sqlite3_vtab_cursor *pCursor, sqlite3_int64 *pRowid) {
char *pzErr = goVRowid(((goVTabCursor*)pCursor)->vTabCursor, pRowid);
if (pzErr) {
return setErrMsg(pCursor, pzErr);
}
return SQLITE_OK;
}
static sqlite3_module goModule = {
0, /* iVersion */
cXCreate, /* xCreate - create a table */
cXConnect, /* xConnect - connect to an existing table */
cXBestIndex, /* xBestIndex - Determine search strategy */
cXDisconnect, /* xDisconnect - Disconnect from a table */
cXDestroy, /* xDestroy - Drop a table */
cXOpen, /* xOpen - open a cursor */
cXClose, /* xClose - close a cursor */
cXFilter, /* xFilter - configure scan constraints */
cXNext, /* xNext - advance a cursor */
cXEof, /* xEof */
cXColumn, /* xColumn - read data */
cXRowid, /* xRowid - read data */
// Not implemented
0, /* xUpdate - write data */
0, /* xBegin - begin transaction */
0, /* xSync - sync transaction */
0, /* xCommit - commit transaction */
0, /* xRollback - rollback transaction */
0, /* xFindFunction - function overloading */
0, /* xRename - rename the table */
0, /* xSavepoint */
0, /* xRelease */
0 /* xRollbackTo */
};
int goSqlite3CreateModule(sqlite3 *db, const char *zName, uintptr_t pClientData) {
return sqlite3_create_module_v2(db, zName, &goModule, (void*) pClientData, goMDestroy);
}

380
vtable.go Normal file
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@ -0,0 +1,380 @@
// Copyright (C) 2014 Yasuhiro Matsumoto <mattn.jp@gmail.com>.
//
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
package sqlite3
/*
#cgo CFLAGS: -std=gnu99
#cgo CFLAGS: -DSQLITE_ENABLE_RTREE -DSQLITE_THREADSAFE
#cgo CFLAGS: -DSQLITE_ENABLE_FTS3 -DSQLITE_ENABLE_FTS3_PARENTHESIS -DSQLITE_ENABLE_FTS4_UNICODE61
#cgo CFLAGS: -DSQLITE_TRACE_SIZE_LIMIT=15
#cgo CFLAGS: -DSQLITE_ENABLE_COLUMN_METADATA=1
#cgo CFLAGS: -Wno-deprecated-declarations
#ifndef USE_LIBSQLITE3
#include <sqlite3-binding.h>
#else
#include <sqlite3.h>
#endif
#include <stdlib.h>
#include <stdint.h>
int goSqlite3CreateModule(sqlite3 *db, const char *zName, uintptr_t pClientData);
static inline char *my_mprintf(char *zFormat, char *arg) {
return sqlite3_mprintf(zFormat, arg);
}
*/
import "C"
import (
"math"
"reflect"
"unsafe"
)
type sqliteModule struct {
c *SQLiteConn
name string
module Module
}
type sqliteVTab struct {
module *sqliteModule
vTab VTab
}
type sqliteVTabCursor struct {
vTab *sqliteVTab
vTabCursor VTabCursor
}
type Op uint8
const (
OpEQ Op = 2
OpGT = 4
OpLE = 8
OpLT = 16
OpGE = 32
OpMATCH = 64
OpLIKE = 65 /* 3.10.0 and later only */
OpGLOB = 66 /* 3.10.0 and later only */
OpREGEXP = 67 /* 3.10.0 and later only */
OpScanUnique = 1 /* Scan visits at most 1 row */
)
type InfoConstraint struct {
Column int
Op Op
Usable bool
}
type InfoOrderBy struct {
Column int
Desc bool
}
func constraints(info *C.sqlite3_index_info) []InfoConstraint {
l := info.nConstraint
var constraints *C.struct_sqlite3_index_constraint = info.aConstraint
slice := (*[1 << 30]C.struct_sqlite3_index_constraint)(unsafe.Pointer(constraints))[:l:l]
cst := make([]InfoConstraint, 0, l)
for _, c := range slice {
var usable bool
if c.usable > 0 {
usable = true
}
cst = append(cst, InfoConstraint{
Column: int(c.iColumn),
Op: Op(c.op),
Usable: usable,
})
}
return cst
}
func orderBys(info *C.sqlite3_index_info) []InfoOrderBy {
l := info.nOrderBy
var obys *C.struct_sqlite3_index_orderby = info.aOrderBy
slice := (*[1 << 30]C.struct_sqlite3_index_orderby)(unsafe.Pointer(obys))[:l:l]
ob := make([]InfoOrderBy, 0, l)
for _, c := range slice {
var desc bool
if c.desc > 0 {
desc = true
}
ob = append(ob, InfoOrderBy{
Column: int(c.iColumn),
Desc: desc,
})
}
return ob
}
// IndexResult is a Go struct represetnation of what eventually ends up in the
// output fields for `sqlite3_index_info`
// See: https://www.sqlite.org/c3ref/index_info.html
type IndexResult struct {
Used []bool // aConstraintUsage
IdxNum int
IdxStr string
AlreadyOrdered bool // orderByConsumed
EstimatedCost float64
EstimatedRows float64
}
// mPrintf is a utility wrapper around sqlite3_mprintf
func mPrintf(format, arg string) *C.char {
cf := C.CString(format)
defer C.free(unsafe.Pointer(cf))
ca := C.CString(arg)
defer C.free(unsafe.Pointer(ca))
return C.my_mprintf(cf, ca)
}
//export goMInit
func goMInit(db, pClientData unsafe.Pointer, argc int, argv **C.char, pzErr **C.char, isCreate int) C.uintptr_t {
m := lookupHandle(uintptr(pClientData)).(*sqliteModule)
if m.c.db != (*C.sqlite3)(db) {
*pzErr = mPrintf("%s", "Inconsistent db handles")
return 0
}
args := make([]string, argc)
var A []*C.char
slice := reflect.SliceHeader{Data: uintptr(unsafe.Pointer(argv)), Len: argc, Cap: argc}
a := reflect.NewAt(reflect.TypeOf(A), unsafe.Pointer(&slice)).Elem().Interface()
for i, s := range a.([]*C.char) {
args[i] = C.GoString(s)
}
var vTab VTab
var err error
if isCreate == 1 {
vTab, err = m.module.Create(m.c, args)
} else {
vTab, err = m.module.Connect(m.c, args)
}
if err != nil {
*pzErr = mPrintf("%s", err.Error())
return 0
}
vt := sqliteVTab{m, vTab}
*pzErr = nil
return C.uintptr_t(newHandle(m.c, &vt))
}
//export goVRelease
func goVRelease(pVTab unsafe.Pointer, isDestroy int) *C.char {
vt := lookupHandle(uintptr(pVTab)).(*sqliteVTab)
var err error
if isDestroy == 1 {
err = vt.vTab.Destroy()
} else {
err = vt.vTab.Disconnect()
}
if err != nil {
return mPrintf("%s", err.Error())
}
return nil
}
//export goVOpen
func goVOpen(pVTab unsafe.Pointer, pzErr **C.char) C.uintptr_t {
vt := lookupHandle(uintptr(pVTab)).(*sqliteVTab)
vTabCursor, err := vt.vTab.Open()
if err != nil {
*pzErr = mPrintf("%s", err.Error())
return 0
}
vtc := sqliteVTabCursor{vt, vTabCursor}
*pzErr = nil
return C.uintptr_t(newHandle(vt.module.c, &vtc))
}
//export goVBestIndex
func goVBestIndex(pVTab unsafe.Pointer, icp unsafe.Pointer) *C.char {
vt := lookupHandle(uintptr(pVTab)).(*sqliteVTab)
info := (*C.sqlite3_index_info)(icp)
csts := constraints(info)
res, err := vt.vTab.BestIndex(csts, orderBys(info))
if err != nil {
return mPrintf("%s", err.Error())
}
if len(res.Used) != len(csts) {
return mPrintf("Result.Used != expected value", "")
}
// Get a pointer to constraint_usage struct so we can update in place.
l := info.nConstraint
var usg *C.struct_sqlite3_index_constraint_usage = info.aConstraintUsage
s := (*[1 << 30]C.struct_sqlite3_index_constraint_usage)(unsafe.Pointer(usg))[:l:l]
index := 1
for i := C.int(0); i < info.nConstraint; i++ {
if res.Used[i] {
s[i].argvIndex = C.int(index)
s[i].omit = C.uchar(1)
index++
}
}
info.idxNum = C.int(res.IdxNum)
idxStr := C.CString(res.IdxStr)
defer C.free(unsafe.Pointer(idxStr))
info.idxStr = idxStr
info.needToFreeIdxStr = C.int(0)
if res.AlreadyOrdered {
info.orderByConsumed = C.int(1)
}
info.estimatedCost = C.double(res.EstimatedCost)
info.estimatedRows = C.sqlite3_int64(res.EstimatedRows)
return nil
}
//export goVClose
func goVClose(pCursor unsafe.Pointer) *C.char {
vtc := lookupHandle(uintptr(pCursor)).(*sqliteVTabCursor)
err := vtc.vTabCursor.Close()
if err != nil {
return mPrintf("%s", err.Error())
}
return nil
}
//export goMDestroy
func goMDestroy(pClientData unsafe.Pointer) {
m := lookupHandle(uintptr(pClientData)).(*sqliteModule)
m.module.DestroyModule()
}
//export goVFilter
func goVFilter(pCursor unsafe.Pointer, idxNum int, idxName *C.char, argc int, argv **C.sqlite3_value) *C.char {
vtc := lookupHandle(uintptr(pCursor)).(*sqliteVTabCursor)
args := (*[(math.MaxInt32 - 1) / unsafe.Sizeof((*C.sqlite3_value)(nil))]*C.sqlite3_value)(unsafe.Pointer(argv))[:argc:argc]
vals := make([]interface{}, 0, argc)
for _, v := range args {
conv, err := callbackArgGeneric(v)
if err != nil {
return mPrintf("%s", err.Error())
}
vals = append(vals, conv.Interface())
}
err := vtc.vTabCursor.Filter(idxNum, C.GoString(idxName), vals)
if err != nil {
return mPrintf("%s", err.Error())
}
return nil
}
//export goVNext
func goVNext(pCursor unsafe.Pointer) *C.char {
vtc := lookupHandle(uintptr(pCursor)).(*sqliteVTabCursor)
err := vtc.vTabCursor.Next()
if err != nil {
return mPrintf("%s", err.Error())
}
return nil
}
//export goVEof
func goVEof(pCursor unsafe.Pointer) C.int {
vtc := lookupHandle(uintptr(pCursor)).(*sqliteVTabCursor)
err := vtc.vTabCursor.EOF()
if err {
return 1
}
return 0
}
//export goVColumn
func goVColumn(pCursor, cp unsafe.Pointer, col int) *C.char {
vtc := lookupHandle(uintptr(pCursor)).(*sqliteVTabCursor)
c := (*Context)(cp)
err := vtc.vTabCursor.Column(c, col)
if err != nil {
return mPrintf("%s", err.Error())
}
return nil
}
//export goVRowid
func goVRowid(pCursor unsafe.Pointer, pRowid *C.sqlite3_int64) *C.char {
vtc := lookupHandle(uintptr(pCursor)).(*sqliteVTabCursor)
rowid, err := vtc.vTabCursor.Rowid()
if err != nil {
return mPrintf("%s", err.Error())
}
*pRowid = C.sqlite3_int64(rowid)
return nil
}
// Module is a "virtual table module", it defines the implementation of a
// virtual tables. See: http://sqlite.org/c3ref/module.html
type Module interface {
// http://sqlite.org/vtab.html#xcreate
Create(c *SQLiteConn, args []string) (VTab, error)
// http://sqlite.org/vtab.html#xconnect
Connect(c *SQLiteConn, args []string) (VTab, error)
// http://sqlite.org/c3ref/create_module.html
DestroyModule()
}
// VTab describes a particular instance of the virtual table.
// See: http://sqlite.org/c3ref/vtab.html
type VTab interface {
// http://sqlite.org/vtab.html#xbestindex
BestIndex([]InfoConstraint, []InfoOrderBy) (*IndexResult, error)
// http://sqlite.org/vtab.html#xdisconnect
Disconnect() error
// http://sqlite.org/vtab.html#sqlite3_module.xDestroy
Destroy() error
// http://sqlite.org/vtab.html#xopen
Open() (VTabCursor, error)
}
// VTabCursor describes cursors that point into the virtual table and are used
// to loop through the virtual table. See: http://sqlite.org/c3ref/vtab_cursor.html
type VTabCursor interface {
// http://sqlite.org/vtab.html#xclose
Close() error
// http://sqlite.org/vtab.html#xfilter
Filter(idxNum int, idxStr string, vals []interface{}) error
// http://sqlite.org/vtab.html#xnext
Next() error
// http://sqlite.org/vtab.html#xeof
EOF() bool
// http://sqlite.org/vtab.html#xcolumn
Column(c *Context, col int) error
// http://sqlite.org/vtab.html#xrowid
Rowid() (int64, error)
}
// DeclareVTab declares the Schema of a virtual table.
// See: http://sqlite.org/c3ref/declare_vtab.html
func (c *SQLiteConn) DeclareVTab(sql string) error {
zSQL := C.CString(sql)
defer C.free(unsafe.Pointer(zSQL))
rv := C.sqlite3_declare_vtab(c.db, zSQL)
if rv != C.SQLITE_OK {
return c.lastError()
}
return nil
}
// CreateModule registers a virtual table implementation.
// See: http://sqlite.org/c3ref/create_module.html
func (c *SQLiteConn) CreateModule(moduleName string, module Module) error {
mname := C.CString(moduleName)
defer C.free(unsafe.Pointer(mname))
udm := sqliteModule{c, moduleName, module}
rv := C.goSqlite3CreateModule(c.db, mname, C.uintptr_t(newHandle(c, &udm)))
if rv != C.SQLITE_OK {
return c.lastError()
}
return nil
}

132
vtable_test.go Normal file
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@ -0,0 +1,132 @@
// Copyright (C) 2014 Yasuhiro Matsumoto <mattn.jp@gmail.com>.
//
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
package sqlite3
import (
"database/sql"
"fmt"
"os"
"testing"
"github.com/stretchr/testify/assert"
)
type testModule struct {
t *testing.T
intarray []int
}
type testVTab struct {
intarray []int
}
type testVTabCursor struct {
vTab *testVTab
index int
}
func (m testModule) Create(c *SQLiteConn, args []string) (VTab, error) {
assert.True(m.t, len(args) == 6, "six arguments expected")
assert.Equal(m.t, "test", args[0], "module name")
assert.Equal(m.t, "main", args[1], "db name")
assert.Equal(m.t, "vtab", args[2], "table name")
assert.Equal(m.t, "'1'", args[3], "first arg")
assert.Equal(m.t, "2", args[4], "second arg")
assert.Equal(m.t, "three", args[5], "third arg")
err := c.DeclareVTab("CREATE TABLE x(test TEXT)")
if err != nil {
return nil, err
}
return &testVTab{m.intarray}, nil
}
func (m testModule) Connect(c *SQLiteConn, args []string) (VTab, error) {
return m.Create(c, args)
}
func (m testModule) DestroyModule() {}
func (v *testVTab) BestIndex(cst []InfoConstraint, ob []InfoOrderBy) (*IndexResult, error) {
used := make([]bool, 0, len(cst))
for range cst {
used = append(used, false)
}
return &IndexResult{
Used: used,
IdxNum: 0,
IdxStr: "test-index",
AlreadyOrdered: true,
EstimatedCost: 100,
EstimatedRows: 200,
}, nil
}
func (v *testVTab) Disconnect() error {
return nil
}
func (v *testVTab) Destroy() error {
return nil
}
func (v *testVTab) Open() (VTabCursor, error) {
return &testVTabCursor{v, 0}, nil
}
func (vc *testVTabCursor) Close() error {
return nil
}
func (vc *testVTabCursor) Filter(idxNum int, idxStr string, vals []interface{}) error {
vc.index = 0
return nil
}
func (vc *testVTabCursor) Next() error {
vc.index++
return nil
}
func (vc *testVTabCursor) EOF() bool {
return vc.index >= len(vc.vTab.intarray)
}
func (vc *testVTabCursor) Column(c *Context, col int) error {
if col != 0 {
return fmt.Errorf("column index out of bounds: %d", col)
}
c.ResultInt(vc.vTab.intarray[vc.index])
return nil
}
func (vc *testVTabCursor) Rowid() (int64, error) {
return int64(vc.index), nil
}
func TestCreateModule(t *testing.T) {
tempFilename := TempFilename(t)
defer os.Remove(tempFilename)
intarray := []int{1, 2, 3}
sql.Register("sqlite3_TestCreateModule", &SQLiteDriver{
ConnectHook: func(conn *SQLiteConn) error {
return conn.CreateModule("test", testModule{t, intarray})
},
})
db, err := sql.Open("sqlite3_TestCreateModule", tempFilename)
assert.Nil(t, err, "could not open db")
_, err = db.Exec("CREATE VIRTUAL TABLE vtab USING test('1', 2, three)")
assert.Nil(t, err, "could not create vtable")
var i, value int
rows, err := db.Query("SELECT rowid, * FROM vtab WHERE test = '3'")
assert.Nil(t, err, "couldn't select from virtual table")
for rows.Next() {
rows.Scan(&i, &value)
assert.Equal(t, intarray[i], value)
}
_, err = db.Exec("DROP TABLE vtab")
assert.Nil(t, err, "couldn't drop virtual table")
}