Golang graph.Next函数代码示例

func TestMultipleConstraintParse(t *testing.T) {
	ts, _ := graph.NewTripleStore("memstore", "", nil)
	for _, tv := range []*quad.Quad{
		{"i", "like", "food", ""},
		{"i", "like", "beer", ""},
		{"you", "like", "beer", ""},
	} {
		ts.AddTriple(tv)
	}
	query := `(
		$a
		(:like :beer)
		(:like "food")
	)`
	it := BuildIteratorTreeForQuery(ts, query)
	if it.Type() != graph.And {
		t.Error("Odd iterator tree. Got: %s", it.DebugString(0))
	}
	out, ok := graph.Next(it)
	if !ok {
		t.Error("Got no results")
	}
	if out != ts.ValueOf("i") {
		t.Errorf("Got %d, expected %d", out, ts.ValueOf("i"))
	}
	_, ok = graph.Next(it)
	if ok {
		t.Error("Too many results")
	}
}

func TestMultipleConstraintParse(t *testing.T) {
	qs, _ := graph.NewQuadStore("memstore", "", nil)
	w, _ := graph.NewQuadWriter("single", qs, nil)
	for _, tv := range []quad.Quad{
		{"i", "like", "food", ""},
		{"i", "like", "beer", ""},
		{"you", "like", "beer", ""},
	} {
		w.AddQuad(tv)
	}
	query := `(
		$a
		(:like :beer)
		(:like "food")
	)`
	it := BuildIteratorTreeForQuery(qs, query)
	if it.Type() != graph.And {
		t.Errorf("Odd iterator tree. Got: %#v", it.Describe())
	}
	if !graph.Next(it) {
		t.Error("Got no results")
	}
	out := it.Result()
	if out != qs.ValueOf("i") {
		t.Errorf("Got %d, expected %d", out, qs.ValueOf("i"))
	}
	if graph.Next(it) {
		t.Error("Too many results")
	}
}

func TestSQLLinkIteration(t *testing.T) {
	if *postgres_path == "" {
		t.SkipNow()
	}
	db, err := newQuadStore(*postgres_path, nil)
	qs := db.(*QuadStore)
	if err != nil {
		t.Fatal(err)
	}
	it := NewSQLLinkIterator(qs, quad.Object, "Humphrey Bogart")
	for graph.Next(it) {
		fmt.Println(it.Result())
	}
	it = NewSQLLinkIterator(qs, quad.Subject, "/en/casablanca_1942")
	s, v := it.sql.buildSQL(true, nil)
	t.Log(s, v)
	c := 0
	for graph.Next(it) {
		fmt.Println(it.Result())
		c += 1
	}
	if c != 18 {
		t.Errorf("Not enough results, got %d expected 18", c)
	}
}

// Next()ing a LinksTo operates as described above.
func (it *LinksTo) Next() bool {
	graph.NextLogIn(it)
	it.runstats.Next += 1
	if graph.Next(it.nextIt) {
		it.runstats.ContainsNext += 1
		it.result = it.nextIt.Result()
		return graph.NextLogOut(it, it.result, true)
	}

	// If there's an error in the 'next' iterator, we save it and we're done.
	it.err = it.nextIt.Err()
	if it.err != nil {
		return false
	}

	// Subiterator is empty, get another one
	if !graph.Next(it.primaryIt) {
		// Possibly save error
		it.err = it.primaryIt.Err()

		// We're out of nodes in our subiterator, so we're done as well.
		return graph.NextLogOut(it, nil, false)
	}
	it.nextIt.Close()
	it.nextIt = it.qs.QuadIterator(it.dir, it.primaryIt.Result())

	// Recurse -- return the first in the next set.
	return it.Next()
}

// Next advances the Or graph.iterator. Because the Or is the union of its
// subiterators, it must produce from all subiterators -- unless it it
// shortcircuiting, in which case, it is the first one that returns anything.
func (it *Or) Next() bool {
	graph.NextLogIn(it)
	var first bool
	for {
		if it.currentIterator == -1 {
			it.currentIterator = 0
			first = true
		}
		curIt := it.internalIterators[it.currentIterator]

		if graph.Next(curIt) {
			it.result = curIt.Result()
			return graph.NextLogOut(it, it.result, true)
		}

		if it.isShortCircuiting && !first {
			break
		}
		it.currentIterator++
		if it.currentIterator == it.itCount {
			break
		}
	}

	return graph.NextLogOut(it, nil, false)
}

func runIteratorWithCallback(it graph.Iterator, ses *Session, callback otto.Value, this otto.FunctionCall, limit int) {
	count := 0
	it, _ = it.Optimize()
	for {
		if ses.doHalt {
			return
		}
		_, ok := graph.Next(it)
		if !ok {
			break
		}
		tags := make(map[string]graph.Value)
		it.TagResults(tags)
		val, _ := this.Otto.ToValue(tagsToValueMap(tags, ses))
		val, _ = callback.Call(this.This, val)
		count++
		if limit >= 0 && count >= limit {
			break
		}
		for it.NextResult() == true {
			if ses.doHalt {
				return
			}
			tags := make(map[string]graph.Value)
			it.TagResults(tags)
			val, _ := this.Otto.ToValue(tagsToValueMap(tags, ses))
			val, _ = callback.Call(this.This, val)
			count++
			if limit >= 0 && count >= limit {
				break
			}
		}
	}
	it.Close()
}

func runIteratorToArray(it graph.Iterator, ses *Session, limit int) []map[string]string {
	output := make([]map[string]string, 0)
	count := 0
	it, _ = it.Optimize()
	for {
		if ses.doHalt {
			return nil
		}
		_, ok := graph.Next(it)
		if !ok {
			break
		}
		tags := make(map[string]graph.Value)
		it.TagResults(tags)
		output = append(output, tagsToValueMap(tags, ses))
		count++
		if limit >= 0 && count >= limit {
			break
		}
		for it.NextResult() == true {
			if ses.doHalt {
				return nil
			}
			tags := make(map[string]graph.Value)
			it.TagResults(tags)
			output = append(output, tagsToValueMap(tags, ses))
			count++
			if limit >= 0 && count >= limit {
				break
			}
		}
	}
	it.Close()
	return output
}

func main() {

	store, err := cayley.NewGraph("bolt", dbPath, nil)
	if err != nil {
		fmt.Println("error in creating database", err)
	}

	path := cayley.StartPath(store, "Article").
		In().
		Tag("link").
		Save("has_image", "image").
		Save("has_title", "title").
		Save("has_description", "description")

	it := path.BuildIterator()
	it, _ = it.Optimize()

	for graph.Next(it) {
		tags := make(map[string]graph.Value)
		it.TagResults(tags)
		fmt.Println(store.NameOf(tags["image"]))
		fmt.Println(store.NameOf(tags["title"]))
		fmt.Println(store.NameOf(tags["description"]))
		fmt.Println(store.NameOf(tags["link"]))
	}

}

// TestQuadStoreQuadsAllIterator iterates the nodes in a fixture and asserts
// the result.
func TestQuadStoreQuadsAllIterator(t *testing.T, ctx context.Context) {
	qs := ContextQuadStore(ctx)

	_, err := WriteFixtureQuadStore(qs, "simple")
	if err != nil {
		t.Errorf("Unexpected error writing fixures: %v", err)
	}

	it := qs.QuadsAllIterator()
	defer it.Reset()
	graph.Next(it)
	t.Logf("%#v\n", it.Result())
	q := qs.Quad(it.Result())
	t.Log(q)
	set := Fixtures.QuadSet("simple").Quads
	var ok bool
	for _, e := range set {
		if e.String() == q.String() {
			ok = true
			break
		}
	}
	if !ok {
		t.Errorf("Failed to find %q during iteration, got:%q", q, set)
	}
}

func (ts *TripleStore) optimizeLinksTo(it *iterator.LinksTo) (graph.Iterator, bool) {
	subs := it.SubIterators()
	if len(subs) != 1 {
		return it, false
	}
	primary := subs[0]
	if primary.Type() == graph.Fixed {
		size, _ := primary.Size()
		if size == 1 {
			val, ok := graph.Next(primary)
			if !ok {
				panic("Sizes lie")
			}
			newIt := ts.TripleIterator(it.Direction(), val)
			nt := newIt.Tagger()
			nt.CopyFrom(it)
			for _, tag := range primary.Tagger().Tags() {
				nt.AddFixed(tag, val)
			}
			return newIt, true
		}
	}
	it.Close()
	return it, false
}

// Returns the Next value from the Or graph.iterator. Because the Or is the
// union of its subiterators, it must produce from all subiterators -- unless
// it's shortcircuiting, in which case, it's the first one that returns anything.
func (it *Or) Next() (graph.Value, bool) {
	graph.NextLogIn(it)
	var curr graph.Value
	var exists bool
	firstTime := false
	for {
		if it.currentIterator == -1 {
			it.currentIterator = 0
			firstTime = true
		}
		curIt := it.internalIterators[it.currentIterator]
		curr, exists = graph.Next(curIt)
		if !exists {
			if it.isShortCircuiting && !firstTime {
				return graph.NextLogOut(it, nil, false)
			}
			it.currentIterator++
			if it.currentIterator == it.itCount {
				return graph.NextLogOut(it, nil, false)
			}
		} else {
			it.result = curr
			return graph.NextLogOut(it, curr, true)
		}
	}
	panic("unreachable")
}

func (it *Materialize) materializeSet() {
	i := 0
	for graph.Next(it.subIt) {
		i++
		if i > abortMaterializeAt {
			it.aborted = true
			break
		}
		id := it.subIt.Result()
		val := id
		if h, ok := id.(Keyer); ok {
			val = h.Key()
		}
		if _, ok := it.containsMap[val]; !ok {
			it.containsMap[val] = len(it.values)
			it.values = append(it.values, nil)
		}
		index := it.containsMap[val]
		tags := make(map[string]graph.Value)
		it.subIt.TagResults(tags)
		it.values[index] = append(it.values[index], result{id: id, tags: tags})
		for it.subIt.NextPath() {
			tags := make(map[string]graph.Value)
			it.subIt.TagResults(tags)
			it.values[index] = append(it.values[index], result{id: id, tags: tags})
		}
	}
	if it.aborted {
		it.values = nil
		it.containsMap = nil
		it.subIt.Reset()
	}
	glog.Infof("Materialization List %d: %#v", it.values)
	it.hasRun = true
}

func iterated(it graph.Iterator) []int {
	var res []int
	for graph.Next(it) {
		res = append(res, it.Result().(int))
	}
	return res
}

func (ts *QuadStore) optimizeLinksTo(it *iterator.LinksTo) (graph.Iterator, bool) {
	subs := it.SubIterators()
	if len(subs) != 1 {
		return it, false
	}
	primary := subs[0]
	if primary.Type() == graph.Fixed {
		size, _ := primary.Size()
		if size == 1 {
			if !graph.Next(primary) {
				panic("unexpected size during optimize")
			}
			val := primary.Result()
			newIt := ts.TripleIterator(it.Direction(), val)
			nt := newIt.Tagger()
			nt.CopyFrom(it)
			for _, tag := range primary.Tagger().Tags() {
				nt.AddFixed(tag, val)
			}
			it.Close()
			return newIt, true
		}
	}
	return it, false
}

func (s *Session) ExecInput(input string, c chan interface{}, _ int) {
	defer close(c)
	var mqlQuery interface{}
	err := json.Unmarshal([]byte(input), &mqlQuery)
	if err != nil {
		return
	}
	s.currentQuery = NewQuery(s)
	s.currentQuery.BuildIteratorTree(mqlQuery)
	if s.currentQuery.isError() {
		return
	}
	it, _ := s.currentQuery.it.Optimize()
	if glog.V(2) {
		b, err := json.MarshalIndent(it.Describe(), "", "  ")
		if err != nil {
			glog.Infof("failed to format description: %v", err)
		} else {
			glog.Infof("%s", b)
		}
	}
	for graph.Next(it) {
		tags := make(map[string]graph.Value)
		it.TagResults(tags)
		c <- tags
		for it.NextPath() == true {
			tags := make(map[string]graph.Value)
			it.TagResults(tags)
			c <- tags
		}
	}
}