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