89 lines
1.8 KiB
Go
89 lines
1.8 KiB
Go
package db0405
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import (
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"errors"
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"slices"
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)
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type Schema struct {
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Table string
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Cols []Column
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PKey []int // indexes of primary key columns
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}
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type Column struct {
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Name string
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Type CellType
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}
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type Row []Cell
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func (schema *Schema) NewRow() Row {
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return make(Row, len(schema.Cols))
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}
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func (row Row) EncodeKey(schema *Schema) []byte
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func EncodeKeyPrefix(schema *Schema, prefix []Cell, positive bool) []byte
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func (row Row) EncodeVal(schema *Schema) (val []byte) {
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check(len(row) == len(schema.Cols))
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for idx, value := range row {
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if !slices.Contains(schema.PKey, idx) {
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check(value.Type == schema.Cols[idx].Type)
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val = row[idx].EncodeVal(val)
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}
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}
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return val
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}
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var ErrOutOfRange = errors.New("out of range")
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func (row Row) DecodeKey(schema *Schema, key []byte) (err error) {
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check(len(row) == len(schema.Cols))
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if len(key) < len(schema.Table)+1 {
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return ErrOutOfRange
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}
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if string(key[:len(schema.Table)+1]) != schema.Table+"\x00" {
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return ErrOutOfRange
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}
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key = key[len(schema.Table)+1:]
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for _, idx := range schema.PKey {
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row[idx] = Cell{Type: schema.Cols[idx].Type}
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if !(len(key) > 0 && key[0] == byte(row[idx].Type)) {
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return errors.New("bad key")
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}
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key = key[1:]
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if key, err = row[idx].DecodeKey(key); err != nil {
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return err
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}
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}
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if !(len(key) == 1 && key[0] == 0x00) {
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return errors.New("bad key")
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}
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return nil
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}
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func (row Row) DecodeVal(schema *Schema, val []byte) (err error) {
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check(len(row) == len(schema.Cols))
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for idx, col := range schema.Cols {
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if slices.Contains(schema.PKey, idx) {
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continue
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}
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row[idx] = Cell{Type: col.Type}
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if val, err = row[idx].DecodeVal(val); err != nil {
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return err
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}
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}
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if len(val) != 0 {
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return errors.New("trailing garbage")
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}
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return nil
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}
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// QzBQWVJJOUhU https://trialofcode.org/
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