query_shape.go

// Copyright 2014 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 graph

type Node struct {
	Id         int      `json:"id"`
	Tags       []string `json:"tags,omitempty"`
	Values     []string `json:"values,omitempty"`
	IsLinkNode bool     `json:"is_link_node"`
	IsFixed    bool     `json:"is_fixed"`
}

type Link struct {
	Source   int `json:"source"`
	Target   int `json:"target"`
	Pred     int `json:"type"`
	LinkNode int `json:"link_node"`
}

type queryShape struct {
	nodes    []Node
	links    []Link
	ts       TripleStore
	nodeId   int
	hasaIds  []int
	hasaDirs []string
}

func OutputQueryShapeForIterator(it Iterator, ts TripleStore, outputMap *map[string]interface{}) {
	qs := &queryShape{}
	qs.nodes = make([]Node, 0)
	qs.links = make([]Link, 0)
	qs.hasaIds = make([]int, 0)
	qs.hasaDirs = make([]string, 0)
	qs.ts = ts
	qs.nodeId = 1

	node := qs.MakeNode(it.Clone())
	qs.AddNode(node)
	(*outputMap)["nodes"] = qs.nodes
	(*outputMap)["links"] = qs.links
}

func (qs *queryShape) AddNode(n *Node) {
	qs.nodes = append(qs.nodes, *n)
}

func (qs *queryShape) AddLink(l *Link) {
	qs.links = append(qs.links, *l)
}

func (qs *queryShape) LastHasa() (int, string) {
	return qs.hasaIds[len(qs.hasaIds)-1], qs.hasaDirs[len(qs.hasaDirs)-1]
}

func (qs *queryShape) PushHasa(i int, s string) {
	qs.hasaIds = append(qs.hasaIds, i)
	qs.hasaDirs = append(qs.hasaDirs, s)
}

func (qs *queryShape) RemoveHasa() {
	qs.hasaIds = qs.hasaIds[:len(qs.hasaIds)-1]
	qs.hasaDirs = qs.hasaDirs[:len(qs.hasaDirs)-1]
}

func (qs *queryShape) StealNode(left *Node, right *Node) {
	for _, v := range right.Values {
		left.Values = append(left.Values, v)
	}
	for _, v := range right.Tags {
		left.Tags = append(left.Tags, v)
	}
	left.IsLinkNode = left.IsLinkNode || right.IsLinkNode
	left.IsFixed = left.IsFixed || right.IsFixed
	for i, link := range qs.links {
		rewrite := false
		if link.LinkNode == right.Id {
			link.LinkNode = left.Id
			rewrite = true
		}
		if link.Source == right.Id {
			link.Source = left.Id
			rewrite = true
		}
		if link.Target == right.Id {
			link.Target = left.Id
			rewrite = true
		}
		if rewrite {
			qs.links = append(append(qs.links[:i], qs.links[i+1:]...), link)
		}
	}
}

func (qs *queryShape) MakeNode(it Iterator) *Node {
	var n Node
	n.IsLinkNode = false
	n.IsFixed = false
	n.Id = qs.nodeId
	n.Tags = make([]string, 0)
	n.Values = make([]string, 0)
	for _, tag := range it.Tags() {
		n.Tags = append(n.Tags, tag)
	}
	for k, _ := range it.FixedTags() {
		n.Tags = append(n.Tags, k)
	}

	switch it.Type() {
	case "and":
		list := it.GetSubIterators()
		for e := list.Front(); e != nil; e = e.Next() {
			subit := e.Value.(Iterator)
			qs.nodeId++
			newNode := qs.MakeNode(subit)
			if subit.Type() != "or" {
				qs.StealNode(&n, newNode)
			} else {
				qs.AddNode(newNode)
				qs.AddLink(&Link{n.Id, newNode.Id, 0, 0})
			}
		}
	case "fixed":
		n.IsFixed = true
		for {
			val, more := it.Next()
			if !more {
				break
			}
			n.Values = append(n.Values, qs.ts.GetNameFor(val))
		}
	case "hasa":
		hasa := it.(*HasaIterator)
		qs.PushHasa(n.Id, hasa.direction)
		qs.nodeId++
		newNode := qs.MakeNode(hasa.primaryIt)
		qs.AddNode(newNode)
		qs.RemoveHasa()
	case "or":
		list := it.GetSubIterators()
		for e := list.Front(); e != nil; e = e.Next() {
			subit := e.Value.(Iterator)
			qs.nodeId++
			newNode := qs.MakeNode(subit)
			if subit.Type() == "or" {
				qs.StealNode(&n, newNode)
			} else {
				qs.AddNode(newNode)
				qs.AddLink(&Link{n.Id, newNode.Id, 0, 0})
			}
		}
	case "linksto":
		n.IsLinkNode = true
		lto := it.(*LinksToIterator)
		qs.nodeId++
		newNode := qs.MakeNode(lto.primaryIt)
		hasaID, hasaDir := qs.LastHasa()
		if (hasaDir == "s" && lto.direction == "o") ||
			(hasaDir == "o" && lto.direction == "s") {
			qs.AddNode(newNode)
			if hasaDir == "s" {
				qs.AddLink(&Link{hasaID, newNode.Id, 0, n.Id})
			} else {
				qs.AddLink(&Link{newNode.Id, hasaID, 0, n.Id})
			}
		} else if lto.primaryIt.Type() == "fixed" {
			qs.StealNode(&n, newNode)
		} else {
			qs.AddNode(newNode)
		}
	case "optional":
		// Unsupported, for the moment
		fallthrough
	case "all":
	}
	return &n
}