Move current result handling out of Base

Delete majority of Base functionality.

graph/iterator/all_iterator.go

@@ -36,6 +36,7 @@ type Int64 struct {
 	tags     graph.Tagger
 	max, min int64
 	at       int64
+	result   graph.Value
 }
 
 // Creates a new Int64 with the given range.
@@ -99,10 +100,19 @@ func (it *Int64) Next() (graph.Value, bool) {
 	if it.at > it.max {
 		it.at = -1
 	}
-	it.Last = val
+	it.result = val
 	return graph.NextLogOut(it, val, true)
 }
 
+// DEPRECATED
+func (it *Int64) ResultTree() *graph.ResultTree {
+	return graph.NewResultTree(it.Result())
+}
+
+func (it *Int64) Result() graph.Value {
+	return it.result
+}
+
 // No sub-iterators.
 func (it *Int64) SubIterators() []graph.Iterator {
 	return nil
@@ -121,7 +131,7 @@ func (it *Int64) Check(tsv graph.Value) bool {
 	graph.CheckLogIn(it, tsv)
 	v := tsv.(int64)
 	if it.min <= v && v <= it.max {
-		it.Last = v
+		it.result = v
 		return graph.CheckLogOut(it, v, true)
 	}
 	return graph.CheckLogOut(it, v, false)

graph/iterator/and_iterator.go

@@ -32,6 +32,7 @@ type And struct {
 	itCount           int
 	primaryIt         graph.Iterator
 	checkList         []graph.Iterator
+	result            graph.Value
 }
 
 // Creates a new And iterator.
@@ -167,11 +168,15 @@ func (it *And) Next() (graph.Value, bool) {
 			return graph.NextLogOut(it, nil, false)
 		}
 		if it.checkSubIts(curr) {
-			it.Last = curr
+			it.result = curr
 			return graph.NextLogOut(it, curr, true)
 		}
 	}
-	panic("Somehow broke out of Next() loop in And")
+	panic("unreachable")
+}
+
+func (it *And) Result() graph.Value {
+	return it.result
 }
 
 // Checks a value against the non-primary iterators, in order.
@@ -195,7 +200,7 @@ func (it *And) checkCheckList(val graph.Value) bool {
 		}
 	}
 	if ok {
-		it.Last = val
+		it.result = val
 	}
 	return graph.CheckLogOut(it, val, ok)
 }
@@ -214,7 +219,7 @@ func (it *And) Check(val graph.Value) bool {
 	if !othersGood {
 		return graph.CheckLogOut(it, val, false)
 	}
-	it.Last = val
+	it.result = val
 	return graph.CheckLogOut(it, val, true)
 }
 

graph/iterator/fixed_iterator.go

@@ -36,6 +36,7 @@ type Fixed struct {
 	values    []graph.Value
 	lastIndex int
 	cmp       Equality
+	result    graph.Value
 }
 
 // Define the signature of an equality function.
@@ -130,7 +131,7 @@ func (it *Fixed) Check(v graph.Value) bool {
 	graph.CheckLogIn(it, v)
 	for _, x := range it.values {
 		if it.cmp(x, v) {
-			it.Last = x
+			it.result = x
 			return graph.CheckLogOut(it, v, true)
 		}
 	}
@@ -144,11 +145,20 @@ func (it *Fixed) Next() (graph.Value, bool) {
 		return graph.NextLogOut(it, nil, false)
 	}
 	out := it.values[it.lastIndex]
-	it.Last = out
+	it.result = out
 	it.lastIndex++
 	return graph.NextLogOut(it, out, true)
 }
 
+// DEPRECATED
+func (it *Fixed) ResultTree() *graph.ResultTree {
+	return graph.NewResultTree(it.Result())
+}
+
+func (it *Fixed) Result() graph.Value {
+	return it.result
+}
+
 // No sub-iterators.
 func (it *Fixed) SubIterators() []graph.Iterator {
 	return nil

graph/iterator/hasa_iterator.go

@@ -53,6 +53,7 @@ type HasA struct {
 	primaryIt graph.Iterator
 	dir       graph.Direction
 	resultIt  graph.Iterator
+	result    graph.Value
 }
 
 // Construct a new HasA iterator, given the triple subiterator, and the triple
@@ -168,7 +169,7 @@ func (it *HasA) GetCheckResult() bool {
 			glog.V(4).Infoln("Triple is", it.ts.Triple(linkVal))
 		}
 		if it.primaryIt.Check(linkVal) {
-			it.Last = it.ts.TripleDirection(linkVal, it.dir)
+			it.result = it.ts.TripleDirection(linkVal, it.dir)
 			return true
 		}
 	}
@@ -205,10 +206,14 @@ func (it *HasA) Next() (graph.Value, bool) {
 	}
 	name := it.ts.Triple(tID).Get(it.dir)
 	val := it.ts.ValueOf(name)
-	it.Last = val
+	it.result = val
 	return graph.NextLogOut(it, val, true)
 }
 
+func (it *HasA) Result() graph.Value {
+	return it.result
+}
+
 // GetStats() returns the statistics on the HasA iterator. This is curious. Next
 // cost is easy, it's an extra call or so on top of the subiterator Next cost.
 // CheckCost involves going to the graph.TripleStore, iterating out values, and hoping

graph/iterator/iterator.go

@@ -18,7 +18,6 @@ package iterator
 // iterators can "inherit" from to get default iterator functionality.
 
 import (
-	"fmt"
 	"strings"
 	"sync/atomic"
 
@@ -34,7 +33,6 @@ func NextUID() uint64 {
 // The Base iterator is the iterator other iterators inherit from to get some
 // default functionality.
 type Base struct {
-	Last    graph.Value
 	canNext bool
 }
 
@@ -44,50 +42,13 @@ func BaseInit(it *Base) {
 	it.canNext = true
 }
 
-// Prints a silly debug string. Most classes override.
-func (it *Base) DebugString(indent int) string {
-	return fmt.Sprintf("%s(base)", strings.Repeat(" ", indent))
-}
-
-// Nothing in a base iterator.
-func (it *Base) Check(v graph.Value) bool {
-	return false
-}
-
-// Base iterators should never appear in a tree if they are, select against
-// them.
-func (it *Base) Stats() graph.IteratorStats {
-	return graph.IteratorStats{100000, 100000, 100000}
-}
-
-// DEPRECATED
-func (it *Base) ResultTree() *graph.ResultTree {
-	tree := graph.NewResultTree(it.Result())
-	return tree
-}
-
-// Nothing in a base iterator.
-func (it *Base) Next() (graph.Value, bool) {
-	return nil, false
-}
-
 func (it *Base) NextResult() bool {
 	return false
 }
 
-// Returns the last result of an iterator.
-func (it *Base) Result() graph.Value {
-	return it.Last
-}
-
 // Accessor
 func (it *Base) CanNext() bool { return it.canNext }
 
-// Nothing to clean up.
-// func (it *Base) Close() {}
-
-func (it *Base) Reset() {}
-
 // Here we define the simplest iterator -- the Null iterator. It contains nothing.
 // It is the empty set. Often times, queries that contain one of these match nothing,
 // so it's important to give it a special iterator.
@@ -149,8 +110,7 @@ func (it *Null) Result() graph.Value {
 }
 
 func (it *Null) ResultTree() *graph.ResultTree {
-	tree := graph.NewResultTree(it.Result())
-	return tree
+	return graph.NewResultTree(it.Result())
 }
 
 func (it *Null) SubIterators() []graph.Iterator {

graph/iterator/linksto_iterator.go

@@ -47,6 +47,7 @@ type LinksTo struct {
 	primaryIt graph.Iterator
 	dir       graph.Direction
 	nextIt    graph.Iterator
+	result    graph.Value
 }
 
 // Construct a new LinksTo iterator around a direction and a subiterator of
@@ -121,7 +122,7 @@ func (it *LinksTo) Check(val graph.Value) bool {
 	graph.CheckLogIn(it, val)
 	node := it.ts.TripleDirection(val, it.dir)
 	if it.primaryIt.Check(node) {
-		it.Last = val
+		it.result = val
 		return graph.CheckLogOut(it, val, true)
 	}
 	return graph.CheckLogOut(it, val, false)
@@ -169,10 +170,14 @@ func (it *LinksTo) Next() (graph.Value, bool) {
 		// Recurse -- return the first in the next set.
 		return it.Next()
 	}
-	it.Last = val
+	it.result = val
 	return graph.NextLogOut(it, val, ok)
 }
 
+func (it *LinksTo) Result() graph.Value {
+	return it.result
+}
+
 // Close our subiterators.
 func (it *LinksTo) Close() {
 	it.nextIt.Close()

graph/iterator/optional_iterator.go

@@ -43,6 +43,7 @@ type Optional struct {
 	tags      graph.Tagger
 	subIt     graph.Iterator
 	lastCheck bool
+	result    graph.Value
 }
 
 // Creates a new optional iterator.
@@ -78,6 +79,9 @@ func (it *Optional) Clone() graph.Iterator {
 	return out
 }
 
+// FIXME(kortschak) When we create a Nexter interface the
+// following two methods need to go away.
+
 // Nexting the iterator is unsupported -- error and return an empty set.
 // (As above, a reasonable alternative would be to Next() an all iterator)
 func (it *Optional) Next() (graph.Value, bool) {
@@ -85,6 +89,15 @@ func (it *Optional) Next() (graph.Value, bool) {
 	return nil, false
 }
 
+// DEPRECATED
+func (it *Optional) ResultTree() *graph.ResultTree {
+	return graph.NewResultTree(it.Result())
+}
+
+func (it *Optional) Result() graph.Value {
+	return it.result
+}
+
 // An optional iterator only has a next result if, (a) last time we checked
 // we had any results whatsoever, and (b) there was another subresult in our
 // optional subbranch.
@@ -106,7 +119,7 @@ func (it *Optional) SubIterators() []graph.Iterator {
 func (it *Optional) Check(val graph.Value) bool {
 	checked := it.subIt.Check(val)
 	it.lastCheck = checked
-	it.Last = val
+	it.result = val
 	return true
 }
 

graph/iterator/or_iterator.go

@@ -36,6 +36,7 @@ type Or struct {
 	internalIterators []graph.Iterator
 	itCount           int
 	currentIterator   int
+	result            graph.Value
 }
 
 func NewOr() *Or {
@@ -169,11 +170,15 @@ func (it *Or) Next() (graph.Value, bool) {
 				return graph.NextLogOut(it, nil, false)
 			}
 		} else {
-			it.Last = curr
+			it.result = curr
 			return graph.NextLogOut(it, curr, true)
 		}
 	}
-	panic("Somehow broke out of Next() loop in Or")
+	panic("unreachable")
+}
+
+func (it *Or) Result() graph.Value {
+	return it.result
 }
 
 // Checks a value against the iterators, in order.
@@ -196,7 +201,7 @@ func (it *Or) Check(val graph.Value) bool {
 	if !anyGood {
 		return graph.CheckLogOut(it, val, false)
 	}
-	it.Last = val
+	it.result = val
 	return graph.CheckLogOut(it, val, true)
 }
 

graph/iterator/value_comparison_iterator.go

@@ -47,12 +47,13 @@ const (
 
 type Comparison struct {
 	Base
-	uid   uint64
-	tags  graph.Tagger
-	subIt graph.Iterator
-	op    Operator
-	val   interface{}
-	ts    graph.TripleStore
+	uid    uint64
+	tags   graph.Tagger
+	subIt  graph.Iterator
+	op     Operator
+	val    interface{}
+	ts     graph.TripleStore
+	result graph.Value
 }
 
 func NewComparison(sub graph.Iterator, op Operator, val interface{}, ts graph.TripleStore) *Comparison {
@@ -141,10 +142,19 @@ func (it *Comparison) Next() (graph.Value, bool) {
 			break
 		}
 	}
-	it.Last = val
+	it.result = val
 	return val, ok
 }
 
+// DEPRECATED
+func (it *Comparison) ResultTree() *graph.ResultTree {
+	return graph.NewResultTree(it.Result())
+}
+
+func (it *Comparison) Result() graph.Value {
+	return it.result
+}
+
 func (it *Comparison) NextResult() bool {
 	for {
 		hasNext := it.subIt.NextResult()
@@ -155,7 +165,7 @@ func (it *Comparison) NextResult() bool {
 			return true
 		}
 	}
-	it.Last = it.subIt.Result()
+	it.result = it.subIt.Result()
 	return true
 }
 
@@ -213,6 +223,6 @@ func (it *Comparison) Stats() graph.IteratorStats {
 	return it.subIt.Stats()
 }
 
-func (it *Base) Size() (int64, bool) {
+func (it *Comparison) Size() (int64, bool) {
 	return 0, true
 }

graph/leveldb/all_iterator.go

@@ -36,6 +36,7 @@ type AllIterator struct {
 	iter   ldbit.Iterator
 	ts     *TripleStore
 	ro     *opt.ReadOptions
+	result graph.Value
 }
 
 func NewAllIterator(prefix string, d graph.Direction, ts *TripleStore) *AllIterator {
@@ -103,7 +104,7 @@ func (it *AllIterator) Clone() graph.Iterator {
 
 func (it *AllIterator) Next() (graph.Value, bool) {
 	if !it.open {
-		it.Last = nil
+		it.result = nil
 		return nil, false
 	}
 	var out []byte
@@ -117,17 +118,25 @@ func (it *AllIterator) Next() (graph.Value, bool) {
 		it.Close()
 		return nil, false
 	}
-	it.Last = out
+	it.result = out
 	return out, true
 }
 
+func (it *AllIterator) ResultTree() *graph.ResultTree {
+	return graph.NewResultTree(it.Result())
+}
+
+func (it *AllIterator) Result() graph.Value {
+	return it.result
+}
+
 // No subiterators.
 func (it *AllIterator) SubIterators() []graph.Iterator {
 	return nil
 }
 
 func (it *AllIterator) Check(v graph.Value) bool {
-	it.Last = v
+	it.result = v
 	return true
 }
 

graph/leveldb/iterator.go

@@ -38,6 +38,7 @@ type Iterator struct {
 	ts             *TripleStore
 	ro             *opt.ReadOptions
 	originalPrefix string
+	result         graph.Value
 }
 
 func NewIterator(prefix string, d graph.Direction, value graph.Value, ts *TripleStore) *Iterator {
@@ -119,22 +120,22 @@ func (it *Iterator) Close() {
 
 func (it *Iterator) Next() (graph.Value, bool) {
 	if it.iter == nil {
-		it.Last = nil
+		it.result = nil
 		return nil, false
 	}
 	if !it.open {
-		it.Last = nil
+		it.result = nil
 		return nil, false
 	}
 	if !it.iter.Valid() {
-		it.Last = nil
+		it.result = nil
 		it.Close()
 		return nil, false
 	}
 	if bytes.HasPrefix(it.iter.Key(), it.nextPrefix) {
 		out := make([]byte, len(it.iter.Key()))
 		copy(out, it.iter.Key())
-		it.Last = out
+		it.result = out
 		ok := it.iter.Next()
 		if !ok {
 			it.Close()
@@ -142,10 +143,18 @@ func (it *Iterator) Next() (graph.Value, bool) {
 		return out, true
 	}
 	it.Close()
-	it.Last = nil
+	it.result = nil
 	return nil, false
 }
 
+func (it *Iterator) ResultTree() *graph.ResultTree {
+	return graph.NewResultTree(it.Result())
+}
+
+func (it *Iterator) Result() graph.Value {
+	return it.result
+}
+
 // No subiterators.
 func (it *Iterator) SubIterators() []graph.Iterator {
 	return nil

graph/memstore/all_iterator.go

@@ -46,6 +46,5 @@ func (it *AllIterator) Next() (graph.Value, bool) {
 	if !ok {
 		return it.Next()
 	}
-	it.Last = next
 	return next, out
 }

graph/memstore/iterator.go

@@ -33,6 +33,7 @@ type Iterator struct {
 	data      string
 	isRunning bool
 	iterLast  Int64
+	result    graph.Value
 }
 
 type Int64 int64
@@ -97,12 +98,20 @@ func (it *Iterator) Close() {}
 
 func (it *Iterator) Next() (graph.Value, bool) {
 	graph.NextLogIn(it)
-	if it.tree.Max() == nil || it.Last == int64(it.tree.Max().(Int64)) {
+	if it.tree.Max() == nil || it.result == int64(it.tree.Max().(Int64)) {
 		return graph.NextLogOut(it, nil, false)
 	}
 	it.iterLast = IterateOne(it.tree, it.iterLast)
-	it.Last = int64(it.iterLast)
-	return graph.NextLogOut(it, it.Last, true)
+	it.result = int64(it.iterLast)
+	return graph.NextLogOut(it, it.result, true)
+}
+
+func (it *Iterator) ResultTree() *graph.ResultTree {
+	return graph.NewResultTree(it.Result())
+}
+
+func (it *Iterator) Result() graph.Value {
+	return it.result
 }
 
 // No subiterators.
@@ -117,7 +126,7 @@ func (it *Iterator) Size() (int64, bool) {
 func (it *Iterator) Check(v graph.Value) bool {
 	graph.CheckLogIn(it, v)
 	if it.tree.Has(Int64(v.(int64))) {
-		it.Last = v
+		it.result = v
 		return graph.CheckLogOut(it, v, true)
 	}
 	return graph.CheckLogOut(it, v, false)

graph/mongo/iterator.go

@@ -39,6 +39,7 @@ type Iterator struct {
 	isAll      bool
 	constraint bson.M
 	collection string
+	result     graph.Value
 }
 
 func NewIterator(ts *TripleStore, collection string, d graph.Direction, val graph.Value) *Iterator {
@@ -158,10 +159,18 @@ func (it *Iterator) Next() (graph.Value, bool) {
 		}
 		return nil, false
 	}
-	it.Last = result.Id
+	it.result = result.Id
 	return result.Id, true
 }
 
+func (it *Iterator) ResultTree() *graph.ResultTree {
+	return graph.NewResultTree(it.Result())
+}
+
+func (it *Iterator) Result() graph.Value {
+	return it.result
+}
+
 // No subiterators.
 func (it *Iterator) SubIterators() []graph.Iterator {
 	return nil
@@ -170,7 +179,7 @@ func (it *Iterator) SubIterators() []graph.Iterator {
 func (it *Iterator) Check(v graph.Value) bool {
 	graph.CheckLogIn(it, v)
 	if it.isAll {
-		it.Last = v
+		it.result = v
 		return graph.CheckLogOut(it, v, true)
 	}
 	var offset int
@@ -186,7 +195,7 @@ func (it *Iterator) Check(v graph.Value) bool {
 	}
 	val := v.(string)[offset : it.ts.hasher.Size()*2+offset]
 	if val == it.hash {
-		it.Last = v
+		it.result = v
 		return graph.CheckLogOut(it, v, true)
 	}
 	return graph.CheckLogOut(it, v, false)