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build_iterator.go
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/
build_iterator.go
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// 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 gremlin
import (
"strconv"
"github.com/barakmich/glog"
"github.com/robertkrimen/otto"
"github.com/google/cayley/graph"
"github.com/google/cayley/graph/iterator"
"github.com/google/cayley/quad"
)
func getStrings(obj *otto.Object, field string) []string {
strings := make([]string, 0)
val, _ := obj.Get(field)
if !val.IsUndefined() {
export, _ := val.Export()
array := export.([]interface{})
for _, arg := range array {
strings = append(strings, arg.(string))
}
}
return strings
}
func getStringArgs(obj *otto.Object) []string { return getStrings(obj, "string_args") }
func buildIteratorTree(obj *otto.Object, ts graph.TripleStore) graph.Iterator {
if !isVertexChain(obj) {
return iterator.NewNull()
}
return buildIteratorTreeHelper(obj, ts, iterator.NewNull())
}
func makeListOfStringsFromArrayValue(obj *otto.Object) []string {
var output []string
lengthValue, _ := obj.Get("length")
length, _ := lengthValue.ToInteger()
ulength := uint32(length)
for index := uint32(0); index < ulength; index += 1 {
name := strconv.FormatInt(int64(index), 10)
value, err := obj.Get(name)
if err != nil {
continue
}
if !value.IsString() {
continue
}
s, _ := value.ToString()
output = append(output, s)
}
return output
}
func buildIteratorFromValue(val otto.Value, ts graph.TripleStore) graph.Iterator {
if val.IsNull() || val.IsUndefined() {
return ts.NodesAllIterator()
}
if val.IsPrimitive() {
thing, _ := val.Export()
switch v := thing.(type) {
case string:
it := ts.FixedIterator()
it.Add(ts.ValueOf(v))
return it
default:
glog.Errorln("Trying to build unknown primitive value.")
}
}
switch val.Class() {
case "Object":
return buildIteratorTree(val.Object(), ts)
case "Array":
// Had better be an array of strings
strings := makeListOfStringsFromArrayValue(val.Object())
it := ts.FixedIterator()
for _, x := range strings {
it.Add(ts.ValueOf(x))
}
return it
case "Number":
fallthrough
case "Boolean":
fallthrough
case "Date":
fallthrough
case "String":
it := ts.FixedIterator()
str, _ := val.ToString()
it.Add(ts.ValueOf(str))
return it
default:
glog.Errorln("Trying to handle unsupported Javascript value.")
return iterator.NewNull()
}
}
func buildInOutIterator(obj *otto.Object, ts graph.TripleStore, base graph.Iterator, isReverse bool) graph.Iterator {
argList, _ := obj.Get("_gremlin_values")
if argList.Class() != "GoArray" {
glog.Errorln("How is arglist not an array? Return nothing.", argList.Class())
return iterator.NewNull()
}
argArray := argList.Object()
lengthVal, _ := argArray.Get("length")
length, _ := lengthVal.ToInteger()
var predicateNodeIterator graph.Iterator
if length == 0 {
predicateNodeIterator = ts.NodesAllIterator()
} else {
zero, _ := argArray.Get("0")
predicateNodeIterator = buildIteratorFromValue(zero, ts)
}
if length >= 2 {
var tags []string
one, _ := argArray.Get("1")
if one.IsString() {
s, _ := one.ToString()
tags = append(tags, s)
} else if one.Class() == "Array" {
tags = makeListOfStringsFromArrayValue(one.Object())
}
for _, tag := range tags {
predicateNodeIterator.Tagger().Add(tag)
}
}
in, out := quad.Subject, quad.Object
if isReverse {
in, out = out, in
}
lto := iterator.NewLinksTo(ts, base, in)
and := iterator.NewAnd()
and.AddSubIterator(iterator.NewLinksTo(ts, predicateNodeIterator, quad.Predicate))
and.AddSubIterator(lto)
return iterator.NewHasA(ts, and, out)
}
func buildIteratorTreeHelper(obj *otto.Object, ts graph.TripleStore, base graph.Iterator) graph.Iterator {
var it graph.Iterator
it = base
// TODO: Better error handling
kindVal, _ := obj.Get("_gremlin_type")
stringArgs := getStringArgs(obj)
var subIt graph.Iterator
prevVal, _ := obj.Get("_gremlin_prev")
if !prevVal.IsObject() {
subIt = base
} else {
subIt = buildIteratorTreeHelper(prevVal.Object(), ts, base)
}
kind, _ := kindVal.ToString()
switch kind {
case "vertex":
if len(stringArgs) == 0 {
it = ts.NodesAllIterator()
} else {
fixed := ts.FixedIterator()
for _, name := range stringArgs {
fixed.Add(ts.ValueOf(name))
}
it = fixed
}
case "tag":
it = subIt
for _, tag := range stringArgs {
it.Tagger().Add(tag)
}
case "save":
all := ts.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 := ts.FixedIterator()
predFixed.Add(ts.ValueOf(stringArgs[0]))
subAnd := iterator.NewAnd()
subAnd.AddSubIterator(iterator.NewLinksTo(ts, predFixed, quad.Predicate))
subAnd.AddSubIterator(iterator.NewLinksTo(ts, all, quad.Object))
hasa := iterator.NewHasA(ts, subAnd, quad.Subject)
and := iterator.NewAnd()
and.AddSubIterator(hasa)
and.AddSubIterator(subIt)
it = and
case "saver":
all := ts.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 := ts.FixedIterator()
predFixed.Add(ts.ValueOf(stringArgs[0]))
subAnd := iterator.NewAnd()
subAnd.AddSubIterator(iterator.NewLinksTo(ts, predFixed, quad.Predicate))
subAnd.AddSubIterator(iterator.NewLinksTo(ts, all, quad.Subject))
hasa := iterator.NewHasA(ts, subAnd, quad.Object)
and := iterator.NewAnd()
and.AddSubIterator(hasa)
and.AddSubIterator(subIt)
it = and
case "has":
fixed := ts.FixedIterator()
if len(stringArgs) < 2 {
return iterator.NewNull()
}
for _, name := range stringArgs[1:] {
fixed.Add(ts.ValueOf(name))
}
predFixed := ts.FixedIterator()
predFixed.Add(ts.ValueOf(stringArgs[0]))
subAnd := iterator.NewAnd()
subAnd.AddSubIterator(iterator.NewLinksTo(ts, predFixed, quad.Predicate))
subAnd.AddSubIterator(iterator.NewLinksTo(ts, fixed, quad.Object))
hasa := iterator.NewHasA(ts, subAnd, quad.Subject)
and := iterator.NewAnd()
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(), ts)
and := iterator.NewAnd()
and.AddSubIterator(subIt)
and.AddSubIterator(argIt)
it = and
case "back":
arg, _ := obj.Get("_gremlin_back_chain")
argIt := buildIteratorTree(arg.Object(), ts)
and := iterator.NewAnd()
and.AddSubIterator(subIt)
and.AddSubIterator(argIt)
it = and
case "is":
fixed := ts.FixedIterator()
for _, name := range stringArgs {
fixed.Add(ts.ValueOf(name))
}
and := iterator.NewAnd()
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(), ts)
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, ts, subIt, false)
it2 := buildInOutIterator(obj, ts, clone, true)
or := iterator.NewOr()
or.AddSubIterator(it1)
or.AddSubIterator(it2)
it = or
case "out":
it = buildInOutIterator(obj, ts, 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(), ts, subIt)
case "followr":
// Follow a morphism
arg, _ := obj.Get("_gremlin_followr")
if isVertexChain(arg.Object()) {
return iterator.NewNull()
}
it = buildIteratorTreeHelper(arg.Object(), ts, subIt)
case "in":
it = buildInOutIterator(obj, ts, subIt, true)
}
return it
}