func exceptMorphism(p *Path) morphism {
	return morphism{
		Name:     "except",
		Reversal: func() morphism { return exceptMorphism(p) },
		Apply: func(qs graph.QuadStore, base graph.Iterator) graph.Iterator {
			subIt := p.BuildIteratorOn(qs)
			notIt := iterator.NewNot(subIt, qs.NodesAllIterator())
			and := iterator.NewAnd(qs)
			and.AddSubIterator(base)
			and.AddSubIterator(notIt)
			return and
		},
	}
}
Example #2
0
func buildIteratorTreeHelper(obj *otto.Object, qs graph.QuadStore, base graph.Iterator) graph.Iterator {
	// TODO: Better error handling
	var (
		it    graph.Iterator
		subIt graph.Iterator
	)

	if prev, _ := obj.Get("_gremlin_prev"); !prev.IsObject() {
		subIt = base
	} else {
		subIt = buildIteratorTreeHelper(prev.Object(), qs, base)
	}

	stringArgs := propertiesOf(obj, "string_args")
	val, _ := obj.Get("_gremlin_type")
	switch val.String() {
	case "vertex":
		if len(stringArgs) == 0 {
			it = qs.NodesAllIterator()
		} else {
			fixed := qs.FixedIterator()
			for _, name := range stringArgs {
				fixed.Add(qs.ValueOf(name))
			}
			it = fixed
		}
	case "tag":
		it = subIt
		for _, tag := range stringArgs {
			it.Tagger().Add(tag)
		}
	case "save":
		all := qs.NodesAllIterator()
		if len(stringArgs) > 2 || len(stringArgs) == 0 {
			return iterator.NewNull()
		}
		if len(stringArgs) == 2 {
			all.Tagger().Add(stringArgs[1])
		} else {
			all.Tagger().Add(stringArgs[0])
		}
		predFixed := qs.FixedIterator()
		predFixed.Add(qs.ValueOf(stringArgs[0]))
		subAnd := iterator.NewAnd(qs)
		subAnd.AddSubIterator(iterator.NewLinksTo(qs, predFixed, quad.Predicate))
		subAnd.AddSubIterator(iterator.NewLinksTo(qs, all, quad.Object))
		hasa := iterator.NewHasA(qs, subAnd, quad.Subject)
		and := iterator.NewAnd(qs)
		and.AddSubIterator(hasa)
		and.AddSubIterator(subIt)
		it = and
	case "saver":
		all := qs.NodesAllIterator()
		if len(stringArgs) > 2 || len(stringArgs) == 0 {
			return iterator.NewNull()
		}
		if len(stringArgs) == 2 {
			all.Tagger().Add(stringArgs[1])
		} else {
			all.Tagger().Add(stringArgs[0])
		}
		predFixed := qs.FixedIterator()
		predFixed.Add(qs.ValueOf(stringArgs[0]))
		subAnd := iterator.NewAnd(qs)
		subAnd.AddSubIterator(iterator.NewLinksTo(qs, predFixed, quad.Predicate))
		subAnd.AddSubIterator(iterator.NewLinksTo(qs, all, quad.Subject))
		hasa := iterator.NewHasA(qs, subAnd, quad.Object)
		and := iterator.NewAnd(qs)
		and.AddSubIterator(hasa)
		and.AddSubIterator(subIt)
		it = and
	case "has":
		fixed := qs.FixedIterator()
		if len(stringArgs) < 2 {
			return iterator.NewNull()
		}
		for _, name := range stringArgs[1:] {
			fixed.Add(qs.ValueOf(name))
		}
		predFixed := qs.FixedIterator()
		predFixed.Add(qs.ValueOf(stringArgs[0]))
		subAnd := iterator.NewAnd(qs)
		subAnd.AddSubIterator(iterator.NewLinksTo(qs, predFixed, quad.Predicate))
		subAnd.AddSubIterator(iterator.NewLinksTo(qs, fixed, quad.Object))
		hasa := iterator.NewHasA(qs, subAnd, quad.Subject)
		and := iterator.NewAnd(qs)
		and.AddSubIterator(hasa)
		and.AddSubIterator(subIt)
		it = and
	case "morphism":
		it = base
	case "and":
		arg, _ := obj.Get("_gremlin_values")
		firstArg, _ := arg.Object().Get("0")
		if !isVertexChain(firstArg.Object()) {
			return iterator.NewNull()
		}
		argIt := buildIteratorTree(firstArg.Object(), qs)

		and := iterator.NewAnd(qs)
		and.AddSubIterator(subIt)
		and.AddSubIterator(argIt)
		it = and
	case "back":
		arg, _ := obj.Get("_gremlin_back_chain")
		argIt := buildIteratorTree(arg.Object(), qs)
		and := iterator.NewAnd(qs)
		and.AddSubIterator(subIt)
		and.AddSubIterator(argIt)
		it = and
	case "is":
		fixed := qs.FixedIterator()
		for _, name := range stringArgs {
			fixed.Add(qs.ValueOf(name))
		}
		and := iterator.NewAnd(qs)
		and.AddSubIterator(fixed)
		and.AddSubIterator(subIt)
		it = and
	case "or":
		arg, _ := obj.Get("_gremlin_values")
		firstArg, _ := arg.Object().Get("0")
		if !isVertexChain(firstArg.Object()) {
			return iterator.NewNull()
		}
		argIt := buildIteratorTree(firstArg.Object(), qs)

		or := iterator.NewOr()
		or.AddSubIterator(subIt)
		or.AddSubIterator(argIt)
		it = or
	case "both":
		// Hardly the most efficient pattern, but the most general.
		// Worth looking into an Optimize() optimization here.
		clone := subIt.Clone()
		it1 := buildInOutIterator(obj, qs, subIt, false)
		it2 := buildInOutIterator(obj, qs, clone, true)

		or := iterator.NewOr()
		or.AddSubIterator(it1)
		or.AddSubIterator(it2)
		it = or
	case "out":
		it = buildInOutIterator(obj, qs, subIt, false)
	case "follow":
		// Follow a morphism
		arg, _ := obj.Get("_gremlin_values")
		firstArg, _ := arg.Object().Get("0")
		if isVertexChain(firstArg.Object()) {
			return iterator.NewNull()
		}
		it = buildIteratorTreeHelper(firstArg.Object(), qs, subIt)
	case "followr":
		// Follow a morphism
		arg, _ := obj.Get("_gremlin_followr")
		if isVertexChain(arg.Object()) {
			return iterator.NewNull()
		}
		it = buildIteratorTreeHelper(arg.Object(), qs, subIt)
	case "in":
		it = buildInOutIterator(obj, qs, subIt, true)
	case "except":
		arg, _ := obj.Get("_gremlin_values")
		firstArg, _ := arg.Object().Get("0")
		if !isVertexChain(firstArg.Object()) {
			return iterator.NewNull()
		}

		allIt := qs.NodesAllIterator()
		toComplementIt := buildIteratorTree(firstArg.Object(), qs)
		notIt := iterator.NewNot(toComplementIt, allIt)

		and := iterator.NewAnd(qs)
		and.AddSubIterator(subIt)
		and.AddSubIterator(notIt)
		it = and
	case "in_predicates":
		it = buildInOutPredicateIterator(obj, qs, subIt, true)
	case "out_predicates":
		it = buildInOutPredicateIterator(obj, qs, subIt, false)
	}
	if it == nil {
		panic("Iterator building does not catch the output iterator in some case.")
	}
	return it
}