Add new builder iterators, v2

Subcommits:

link iterator next/contains

implement sql_node_iterator next/buildsql

fix optimizers

graph/sql/sql_link_iterator_test.go

@@ -0,0 +1,87 @@
+// Copyright 2015 The Cayley Authors. All rights reserved.
+//
+// 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 sql
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/google/cayley/graph"
+	"github.com/google/cayley/graph/iterator"
+	"github.com/google/cayley/quad"
+)
+
+func TestSQLLink(t *testing.T) {
+	it := NewSQLLinkIterator(nil, quad.Object, "cool")
+	s, v := it.buildSQL(true, nil)
+	fmt.Println(s, v)
+}
+
+func TestSQLLinkIteration(t *testing.T) {
+	if *dbpath == "" {
+		t.SkipNow()
+	}
+	db, err := newQuadStore(*dbpath, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	it := NewSQLLinkIterator(db.(*QuadStore), quad.Object, "Humphrey Bogart")
+	for graph.Next(it) {
+		fmt.Println(it.Result())
+	}
+	it = NewSQLLinkIterator(db.(*QuadStore), quad.Subject, "/en/casablanca_1942")
+	s, v := it.buildSQL(true, nil)
+	fmt.Println(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)
+	}
+}
+
+func TestSQLNodeIteration(t *testing.T) {
+	if *dbpath == "" {
+		t.SkipNow()
+	}
+	db, err := newQuadStore(*dbpath, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	link := NewSQLLinkIterator(db.(*QuadStore), quad.Object, "/en/humphrey_bogart")
+	it := &SQLNodeIterator{
+		uid:       iterator.NextUID(),
+		qs:        db.(*QuadStore),
+		tableName: newTableName(),
+		linkIts: []sqlItDir{
+			sqlItDir{it: link,
+				dir: quad.Subject,
+			},
+		},
+	}
+	s, v := it.buildSQL(true, nil)
+	fmt.Println(s, v)
+	c := 0
+	for graph.Next(it) {
+		fmt.Println(it.Result())
+		c += 1
+	}
+	if c != 56 {
+		t.Errorf("Not enough results, got %d expected 56", c)
+	}
+
+}