surrealpatch/db/select.go
2016-09-21 00:34:21 +01:00

81 lines
2 KiB
Go

// Copyright © 2016 Abcum Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package db
import (
"github.com/abcum/surreal/kvs"
"github.com/abcum/surreal/sql"
"github.com/abcum/surreal/util/item"
"github.com/abcum/surreal/util/keys"
)
func executeSelectStatement(txn kvs.TX, ast *sql.SelectStatement) (out []interface{}, err error) {
if txn == nil {
txn, err = db.Txn(false)
if err != nil {
return
}
defer txn.Close()
}
for _, w := range ast.What {
if what, ok := w.(*sql.Thing); ok {
key := &keys.Thing{KV: ast.KV, NS: ast.NS, DB: ast.DB, TB: what.TB, ID: what.ID}
kv, _ := txn.Get(key.Encode())
doc := item.New(kv, txn, key)
if ret, err := detect(doc, ast); err != nil {
return nil, err
} else if ret != nil {
out = append(out, ret)
}
}
if what, ok := w.(*sql.Table); ok {
beg := &keys.Thing{KV: ast.KV, NS: ast.NS, DB: ast.DB, TB: what.TB, ID: keys.Prefix}
end := &keys.Thing{KV: ast.KV, NS: ast.NS, DB: ast.DB, TB: what.TB, ID: keys.Suffix}
kvs, _ := txn.RGet(beg.Encode(), end.Encode(), 0)
for _, kv := range kvs {
doc := item.New(kv, txn, nil)
if ret, err := detect(doc, ast); err != nil {
return nil, err
} else if ret != nil {
out = append(out, ret)
}
}
}
}
return
}
func detect(doc *item.Doc, ast *sql.SelectStatement) (out interface{}, err error) {
if !doc.Check(ast.Cond) {
return
}
if !doc.Allow("SELECT") {
return nil, nil
}
out = doc.Blaze(ast)
return
}