refactor to SQL builder iterators and standard iterator wrapper
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b754810c6e
commit
3e02bb2b71
5 changed files with 453 additions and 593 deletions
341
graph/sql/sql_iterator.go
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341
graph/sql/sql_iterator.go
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// Copyright 2015 The Cayley Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package sql
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import (
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"database/sql"
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"fmt"
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"strings"
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"github.com/barakmich/glog"
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"github.com/google/cayley/graph"
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"github.com/google/cayley/graph/iterator"
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"github.com/google/cayley/quad"
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)
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var sqlType graph.Type
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func init() {
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sqlType = graph.RegisterIterator("sql")
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}
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type SQLIterator struct {
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uid uint64
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qs *QuadStore
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cursor *sql.Rows
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err error
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sql sqlIterator
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result map[string]string
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resultIndex int
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resultList [][]string
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resultNext [][]string
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cols []string
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}
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func (it *SQLIterator) Clone() graph.Iterator {
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m := &SQLIterator{
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uid: iterator.NextUID(),
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qs: it.qs,
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sql: it.sql.sqlClone(),
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}
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return m
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}
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func (it *SQLIterator) UID() uint64 {
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return it.uid
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}
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func (it *SQLIterator) Reset() {
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it.err = nil
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it.Close()
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}
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func (it *SQLIterator) Err() error {
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return it.err
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}
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func (it *SQLIterator) Close() error {
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if it.cursor != nil {
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err := it.cursor.Close()
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if err != nil {
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return err
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}
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it.cursor = nil
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}
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return nil
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}
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func (it *SQLIterator) Tagger() *graph.Tagger {
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return it.sql.Tagger()
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}
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func (it *SQLIterator) Result() graph.Value {
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return it.sql.Result()
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}
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func (it *SQLIterator) TagResults(dst map[string]graph.Value) {
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for tag, value := range it.result {
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if tag == "__execd" {
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for _, tag := range it.Tagger().Tags() {
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dst[tag] = value
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}
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continue
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}
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dst[tag] = value
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}
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for tag, value := range it.Tagger().Fixed() {
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dst[tag] = value
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}
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}
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func (it *SQLIterator) Type() graph.Type {
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return sqlType
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}
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func (it *SQLIterator) SubIterators() []graph.Iterator {
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return nil
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}
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func (it *SQLIterator) Sorted() bool { return false }
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func (it *SQLIterator) Optimize() (graph.Iterator, bool) { return it, false }
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func (it *SQLIterator) Size() (int64, bool) {
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return it.sql.Size(it.qs)
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}
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func (it *SQLIterator) Describe() graph.Description {
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size, _ := it.Size()
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return graph.Description{
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UID: it.UID(),
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Name: it.sql.Describe(),
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Type: it.Type(),
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Size: size,
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}
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}
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func (it *SQLIterator) Stats() graph.IteratorStats {
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size, _ := it.Size()
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return graph.IteratorStats{
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ContainsCost: 1,
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NextCost: 5,
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Size: size,
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}
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}
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func (it *SQLIterator) NextPath() bool {
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it.resultIndex += 1
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if it.resultIndex >= len(it.resultList) {
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return false
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}
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it.buildResult(it.resultIndex)
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return true
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}
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func (it *SQLIterator) Next() bool {
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var err error
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graph.NextLogIn(it)
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if it.cursor == nil {
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err = it.makeCursor(true, nil)
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it.cols, err = it.cursor.Columns()
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if err != nil {
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glog.Errorf("Couldn't get columns")
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it.err = err
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it.cursor.Close()
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return false
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}
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// iterate the first one
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if !it.cursor.Next() {
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glog.V(4).Infoln("sql: No next")
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err := it.cursor.Err()
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if err != nil {
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glog.Errorf("Cursor error in SQL: %v", err)
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it.err = err
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}
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it.cursor.Close()
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return false
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}
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s, err := scan(it.cursor, len(it.cols))
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if err != nil {
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it.err = err
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it.cursor.Close()
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return false
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}
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it.resultNext = append(it.resultNext, s)
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}
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if it.resultList != nil && it.resultNext == nil {
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// We're on something and there's no next
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return false
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}
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it.resultList = it.resultNext
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it.resultNext = nil
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it.resultIndex = 0
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for {
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if !it.cursor.Next() {
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glog.V(4).Infoln("sql: No next")
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err := it.cursor.Err()
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if err != nil {
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glog.Errorf("Cursor error in SQL: %v", err)
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it.err = err
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}
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it.cursor.Close()
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break
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}
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s, err := scan(it.cursor, len(it.cols))
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if err != nil {
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it.err = err
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it.cursor.Close()
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return false
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}
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if it.sql.sameTopResult(it.resultList[0], s) {
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it.resultList = append(it.resultList, s)
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} else {
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it.resultNext = append(it.resultNext, s)
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break
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}
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}
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if len(it.resultList) == 0 {
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return graph.NextLogOut(it, nil, false)
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}
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it.buildResult(0)
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return graph.NextLogOut(it, it.Result(), true)
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}
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func (it *SQLIterator) Contains(v graph.Value) bool {
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var err error
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if ok, res := it.sql.quickContains(v); ok {
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return res
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}
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err = it.makeCursor(false, v)
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if err != nil {
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glog.Errorf("Couldn't make query: %v", err)
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it.err = err
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it.cursor.Close()
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return false
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}
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it.cols, err = it.cursor.Columns()
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if err != nil {
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glog.Errorf("Couldn't get columns")
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it.err = err
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it.cursor.Close()
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return false
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}
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it.resultList = nil
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for {
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if !it.cursor.Next() {
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glog.V(4).Infoln("sql: No next")
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err := it.cursor.Err()
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if err != nil {
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glog.Errorf("Cursor error in SQL: %v", err)
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it.err = err
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}
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it.cursor.Close()
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break
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}
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s, err := scan(it.cursor, len(it.cols))
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if err != nil {
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it.err = err
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it.cursor.Close()
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return false
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}
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it.resultList = append(it.resultList, s)
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}
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it.cursor.Close()
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it.cursor = nil
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if len(it.resultList) != 0 {
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it.resultIndex = 0
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it.buildResult(0)
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return true
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}
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return false
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}
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func scan(cursor *sql.Rows, nCols int) ([]string, error) {
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pointers := make([]interface{}, nCols)
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container := make([]string, nCols)
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for i, _ := range pointers {
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pointers[i] = &container[i]
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}
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err := cursor.Scan(pointers...)
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if err != nil {
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glog.Errorf("Error scanning iterator: %v", err)
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return nil, err
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}
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return container, nil
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}
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func (it *SQLIterator) buildResult(i int) {
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it.result = it.sql.buildResult(it.resultList[i], it.cols)
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}
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func (it *SQLIterator) makeCursor(next bool, value graph.Value) error {
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if it.cursor != nil {
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it.cursor.Close()
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}
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var q string
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var values []string
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q, values = it.sql.buildSQL(next, value)
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q = convertToPostgres(q, values)
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ivalues := make([]interface{}, 0, len(values))
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for _, v := range values {
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ivalues = append(ivalues, v)
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}
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cursor, err := it.qs.db.Query(q, ivalues...)
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if err != nil {
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glog.Errorf("Couldn't get cursor from SQL database: %v", err)
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cursor = nil
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return err
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}
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it.cursor = cursor
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return nil
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}
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func convertToPostgres(query string, values []string) string {
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for i := 1; i <= len(values); i++ {
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query = strings.Replace(query, "?", fmt.Sprintf("$%d", i), 1)
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}
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return query
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}
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func NewSQLLinkIterator(qs *QuadStore, d quad.Direction, val string) *SQLIterator {
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l := &SQLIterator{
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uid: iterator.NextUID(),
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qs: qs,
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sql: &SQLLinkIterator{
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constraints: []constraint{
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constraint{
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dir: d,
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vals: []string{val},
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},
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},
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tableName: newTableName(),
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size: 0,
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},
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}
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return l
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}
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func NewSQLIterator(qs *QuadStore, sql sqlIterator) *SQLIterator {
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l := &SQLIterator{
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uid: iterator.NextUID(),
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qs: qs,
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sql: sql,
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}
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return l
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}
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