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package main
import (
"fmt"
"github.com/mattn/go-sqlite3"
)
type seriesModule struct{}
func (m *seriesModule) EponymousOnlyModule() {}
func (m *seriesModule) Create(c *sqlite3.SQLiteConn, args []string) (sqlite3.VTab, error) {
err := c.DeclareVTab(fmt.Sprintf(`
CREATE TABLE %s (
value INT,
start HIDDEN,
stop HIDDEN,
step HIDDEN
)`, args[0]))
if err != nil {
return nil, err
}
return &seriesTable{0, 0, 1}, nil
}
func (m *seriesModule) Connect(c *sqlite3.SQLiteConn, args []string) (sqlite3.VTab, error) {
return m.Create(c, args)
}
func (m *seriesModule) DestroyModule() {}
type seriesTable struct {
start int64
stop int64
step int64
}
func (v *seriesTable) Open() (sqlite3.VTabCursor, error) {
return &seriesCursor{v, 0}, nil
}
func (v *seriesTable) BestIndex(csts []sqlite3.InfoConstraint, ob []sqlite3.InfoOrderBy) (*sqlite3.IndexResult, error) {
used := make([]bool, len(csts))
for c, cst := range csts {
if cst.Usable && cst.Op == sqlite3.OpEQ {
used[c] = true
}
}
return &sqlite3.IndexResult{
IdxNum: 0,
IdxStr: "default",
Used: used,
}, nil
}
func (v *seriesTable) Disconnect() error { return nil }
func (v *seriesTable) Destroy() error { return nil }
type seriesCursor struct {
*seriesTable
value int64
}
func (vc *seriesCursor) Column(c *sqlite3.SQLiteContext, col int) error {
switch col {
case 0:
c.ResultInt64(vc.value)
case 1:
c.ResultInt64(vc.seriesTable.start)
case 2:
c.ResultInt64(vc.seriesTable.stop)
case 3:
c.ResultInt64(vc.seriesTable.step)
}
return nil
}
func (vc *seriesCursor) Filter(idxNum int, idxStr string, vals []interface{}) error {
switch {
case len(vals) < 1:
vc.seriesTable.start = 0
vc.seriesTable.stop = 1000
vc.value = vc.seriesTable.start
case len(vals) < 2:
vc.seriesTable.start = vals[0].(int64)
vc.seriesTable.stop = 1000
vc.value = vc.seriesTable.start
case len(vals) < 3:
vc.seriesTable.start = vals[0].(int64)
vc.seriesTable.stop = vals[1].(int64)
vc.value = vc.seriesTable.start
case len(vals) < 4:
vc.seriesTable.start = vals[0].(int64)
vc.seriesTable.stop = vals[1].(int64)
vc.seriesTable.step = vals[2].(int64)
}
return nil
}
func (vc *seriesCursor) Next() error {
vc.value += vc.step
return nil
}
func (vc *seriesCursor) EOF() bool {
return vc.value > vc.stop
}
func (vc *seriesCursor) Rowid() (int64, error) {
return int64(vc.value), nil
}
func (vc *seriesCursor) Close() error {
return nil
}
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