Adding the challenge 0305

0305/table.go

@@ -0,0 +1,108 @@
+package db0305
+
+import (
+	"encoding/json"
+	"errors"
+)
+
+type DB struct {
+	KV     KV
+	tables map[string]Schema
+}
+
+func (db *DB) Open() error {
+	db.tables = map[string]Schema{}
+	return db.KV.Open()
+}
+
+func (db *DB) Close() error { return db.KV.Close() }
+
+func (db *DB) Select(schema *Schema, row Row) (ok bool, err error) {
+	key := row.EncodeKey(schema)
+	val, ok, err := db.KV.Get(key)
+	if err != nil || !ok {
+		return ok, err
+	}
+	if err = row.DecodeVal(schema, val); err != nil {
+		return false, err
+	}
+	return true, nil
+}
+
+func (db *DB) Insert(schema *Schema, row Row) (updated bool, err error) {
+	key := row.EncodeKey(schema)
+	val := row.EncodeVal(schema)
+	return db.KV.SetEx(key, val, ModeInsert)
+}
+
+func (db *DB) Upsert(schema *Schema, row Row) (updated bool, err error) {
+	key := row.EncodeKey(schema)
+	val := row.EncodeVal(schema)
+	return db.KV.SetEx(key, val, ModeUpsert)
+}
+
+func (db *DB) Update(schema *Schema, row Row) (updated bool, err error) {
+	key := row.EncodeKey(schema)
+	val := row.EncodeVal(schema)
+	return db.KV.SetEx(key, val, ModeUpdate)
+}
+
+func (db *DB) Delete(schema *Schema, row Row) (deleted bool, err error) {
+	key := row.EncodeKey(schema)
+	return db.KV.Del(key)
+}
+
+type SQLResult struct {
+	Updated int
+	Header  []string
+	Values  []Row
+}
+
+func (db *DB) ExecStmt(stmt interface{}) (r SQLResult, err error) {
+	switch ptr := stmt.(type) {
+	case *StmtCreatTable:
+		err = db.execCreateTable(ptr)
+	case *StmtSelect:
+		r.Header = ptr.cols
+		r.Values, err = db.execSelect(ptr)
+	case *StmtInsert:
+		r.Updated, err = db.execInsert(ptr)
+	case *StmtUpdate:
+		r.Updated, err = db.execUpdate(ptr)
+	case *StmtDelete:
+		r.Updated, err = db.execDelete(ptr)
+	default:
+		panic("unreachable")
+	}
+	return
+}
+
+func (db *DB) execCreateTable(stmt *StmtCreatTable) (err error)
+
+func (db *DB) GetSchema(table string) (Schema, error) {
+	schema, ok := db.tables[table]
+	if !ok {
+		val, ok, err := db.KV.Get([]byte("@schema_" + table))
+		if err == nil && ok {
+			err = json.Unmarshal(val, &schema)
+		}
+		if err != nil {
+			return Schema{}, err
+		}
+		if !ok {
+			return Schema{}, errors.New("table is not found")
+		}
+		db.tables[table] = schema
+	}
+	return schema, nil
+}
+
+func (db *DB) execSelect(stmt *StmtSelect) ([]Row, error)
+
+func (db *DB) execInsert(stmt *StmtInsert) (count int, err error)
+
+func (db *DB) execUpdate(stmt *StmtUpdate) (count int, err error)
+
+func (db *DB) execDelete(stmt *StmtDelete) (count int, err error)
+
+// QzBQWVJJOUhU https://trialofcode.org/