From b498a06a7b59e1e35af11ce6c66012c44dfbba14 Mon Sep 17 00:00:00 2001
From: kortschak <dan.kortschak@adelaide.edu.au>
Date: Wed, 30 Jul 2014 15:21:48 +0930
Subject: [PATCH] Intermediate step in removal of Base

We are marking types that will be Nexters and ResultNexters (I want a
better name for this one).
---
 graph/iterator/all_iterator.go              |  8 +++++---
 graph/iterator/and_iterator.go              |  4 +---
 graph/iterator/fixed_iterator.go            |  8 +++++---
 graph/iterator/hasa_iterator.go             |  4 +---
 graph/iterator/iterator.go                  | 13 +------------
 graph/iterator/linksto_iterator.go          |  4 +---
 graph/iterator/optional_iterator.go         | 13 ++++++-------
 graph/iterator/or_iterator.go               |  8 ++------
 graph/iterator/value_comparison_iterator.go |  4 +---
 graph/leveldb/all_iterator.go               |  5 ++++-
 graph/leveldb/iterator.go                   |  5 ++++-
 graph/memstore/iterator.go                  |  8 +++++---
 graph/mongo/iterator.go                     | 14 ++++++--------
 13 files changed, 42 insertions(+), 56 deletions(-)

diff --git a/graph/iterator/all_iterator.go b/graph/iterator/all_iterator.go
index 9466cb4..8394a0e 100644
--- a/graph/iterator/all_iterator.go
+++ b/graph/iterator/all_iterator.go
@@ -41,14 +41,12 @@ type Int64 struct {
 
 // Creates a new Int64 with the given range.
 func NewInt64(min, max int64) *Int64 {
-	all := Int64{
+	return &Int64{
 		uid: NextUID(),
 		min: min,
 		max: max,
 		at:  min,
 	}
-	BaseInit(&all.Base)
-	return &all
 }
 
 func (it *Int64) UID() uint64 {
@@ -113,6 +111,10 @@ func (it *Int64) Result() graph.Value {
 	return it.result
 }
 
+func (it *Int64) NextResult() bool {
+	return false
+}
+
 // No sub-iterators.
 func (it *Int64) SubIterators() []graph.Iterator {
 	return nil
diff --git a/graph/iterator/and_iterator.go b/graph/iterator/and_iterator.go
index 938d9f8..ba7b70b 100644
--- a/graph/iterator/and_iterator.go
+++ b/graph/iterator/and_iterator.go
@@ -37,12 +37,10 @@ type And struct {
 
 // Creates a new And iterator.
 func NewAnd() *And {
-	and := And{
+	return &And{
 		uid:               NextUID(),
 		internalIterators: make([]graph.Iterator, 0, 20),
 	}
-	BaseInit(&and.Base)
-	return &and
 }
 
 func (it *And) UID() uint64 {
diff --git a/graph/iterator/fixed_iterator.go b/graph/iterator/fixed_iterator.go
index 82e308a..2caa8e9 100644
--- a/graph/iterator/fixed_iterator.go
+++ b/graph/iterator/fixed_iterator.go
@@ -57,13 +57,11 @@ func newFixed() *Fixed {
 
 // Creates a new Fixed iterator with a custom comparitor.
 func NewFixedIteratorWithCompare(compareFn Equality) *Fixed {
-	it := Fixed{
+	return &Fixed{
 		uid:    NextUID(),
 		values: make([]graph.Value, 0, 20),
 		cmp:    compareFn,
 	}
-	BaseInit(&it.Base)
-	return &it
 }
 
 func (it *Fixed) UID() uint64 {
@@ -159,6 +157,10 @@ func (it *Fixed) Result() graph.Value {
 	return it.result
 }
 
+func (it *Fixed) NextResult() bool {
+	return false
+}
+
 // No sub-iterators.
 func (it *Fixed) SubIterators() []graph.Iterator {
 	return nil
diff --git a/graph/iterator/hasa_iterator.go b/graph/iterator/hasa_iterator.go
index ea9d2cc..8d9ab46 100644
--- a/graph/iterator/hasa_iterator.go
+++ b/graph/iterator/hasa_iterator.go
@@ -59,14 +59,12 @@ type HasA struct {
 // Construct a new HasA iterator, given the triple subiterator, and the triple
 // direction for which it stands.
 func NewHasA(ts graph.TripleStore, subIt graph.Iterator, d graph.Direction) *HasA {
-	hasa := HasA{
+	return &HasA{
 		uid:       NextUID(),
 		ts:        ts,
 		primaryIt: subIt,
 		dir:       d,
 	}
-	BaseInit(&hasa.Base)
-	return &hasa
 }
 
 func (it *HasA) UID() uint64 {
diff --git a/graph/iterator/iterator.go b/graph/iterator/iterator.go
index cb06965..e290dc3 100644
--- a/graph/iterator/iterator.go
+++ b/graph/iterator/iterator.go
@@ -33,21 +33,10 @@ func NextUID() uint64 {
 // The Base iterator is the iterator other iterators inherit from to get some
 // default functionality.
 type Base struct {
-	canNext bool
-}
-
-// Called by subclases.
-func BaseInit(it *Base) {
-	// Your basic iterator is nextable
-	it.canNext = true
-}
-
-func (it *Base) NextResult() bool {
-	return false
 }
 
 // Accessor
-func (it *Base) CanNext() bool { return it.canNext }
+func (it *Base) CanNext() bool { return true }
 
 // 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,
diff --git a/graph/iterator/linksto_iterator.go b/graph/iterator/linksto_iterator.go
index 80071c4..fa7cf29 100644
--- a/graph/iterator/linksto_iterator.go
+++ b/graph/iterator/linksto_iterator.go
@@ -53,15 +53,13 @@ type LinksTo struct {
 // Construct a new LinksTo iterator around a direction and a subiterator of
 // nodes.
 func NewLinksTo(ts graph.TripleStore, it graph.Iterator, d graph.Direction) *LinksTo {
-	lto := LinksTo{
+	return &LinksTo{
 		uid:       NextUID(),
 		ts:        ts,
 		primaryIt: it,
 		dir:       d,
 		nextIt:    &Null{},
 	}
-	BaseInit(&lto.Base)
-	return &lto
 }
 
 func (it *LinksTo) UID() uint64 {
diff --git a/graph/iterator/optional_iterator.go b/graph/iterator/optional_iterator.go
index e87549b..7b9435f 100644
--- a/graph/iterator/optional_iterator.go
+++ b/graph/iterator/optional_iterator.go
@@ -38,7 +38,6 @@ import (
 // An optional iterator has the sub-constraint iterator we wish to be optional
 // and whether the last check we received was true or false.
 type Optional struct {
-	Base
 	uid       uint64
 	tags      graph.Tagger
 	subIt     graph.Iterator
@@ -48,14 +47,14 @@ type Optional struct {
 
 // Creates a new optional iterator.
 func NewOptional(it graph.Iterator) *Optional {
-	var o Optional
-	BaseInit(&o.Base)
-	o.canNext = false
-	o.subIt = it
-	o.uid = NextUID()
-	return &o
+	return &Optional{
+		uid:   NextUID(),
+		subIt: it,
+	}
 }
 
+func (it *Optional) CanNext() bool { return false }
+
 func (it *Optional) UID() uint64 {
 	return it.uid
 }
diff --git a/graph/iterator/or_iterator.go b/graph/iterator/or_iterator.go
index 20318bf..db323ed 100644
--- a/graph/iterator/or_iterator.go
+++ b/graph/iterator/or_iterator.go
@@ -40,24 +40,20 @@ type Or struct {
 }
 
 func NewOr() *Or {
-	or := Or{
+	return &Or{
 		uid:               NextUID(),
 		internalIterators: make([]graph.Iterator, 0, 20),
 		currentIterator:   -1,
 	}
-	BaseInit(&or.Base)
-	return &or
 }
 
 func NewShortCircuitOr() *Or {
-	or := Or{
+	return &Or{
 		uid:               NextUID(),
 		internalIterators: make([]graph.Iterator, 0, 20),
 		isShortCircuiting: true,
 		currentIterator:   -1,
 	}
-	BaseInit(&or.Base)
-	return &or
 }
 
 func (it *Or) UID() uint64 {
diff --git a/graph/iterator/value_comparison_iterator.go b/graph/iterator/value_comparison_iterator.go
index 6dfd7c5..ab5e698 100644
--- a/graph/iterator/value_comparison_iterator.go
+++ b/graph/iterator/value_comparison_iterator.go
@@ -57,15 +57,13 @@ type Comparison struct {
 }
 
 func NewComparison(sub graph.Iterator, op Operator, val interface{}, ts graph.TripleStore) *Comparison {
-	vc := Comparison{
+	return &Comparison{
 		uid:   NextUID(),
 		subIt: sub,
 		op:    op,
 		val:   val,
 		ts:    ts,
 	}
-	BaseInit(&vc.Base)
-	return &vc
 }
 
 func (it *Comparison) UID() uint64 {
diff --git a/graph/leveldb/all_iterator.go b/graph/leveldb/all_iterator.go
index 27cb144..673fbb9 100644
--- a/graph/leveldb/all_iterator.go
+++ b/graph/leveldb/all_iterator.go
@@ -53,7 +53,6 @@ func NewAllIterator(prefix string, d graph.Direction, ts *TripleStore) *AllItera
 		open:   true,
 		ts:     ts,
 	}
-	iterator.BaseInit(&it.Base)
 
 	it.iter.Seek(it.prefix)
 	if !it.iter.Valid() {
@@ -130,6 +129,10 @@ func (it *AllIterator) Result() graph.Value {
 	return it.result
 }
 
+func (it *AllIterator) NextResult() bool {
+	return false
+}
+
 // No subiterators.
 func (it *AllIterator) SubIterators() []graph.Iterator {
 	return nil
diff --git a/graph/leveldb/iterator.go b/graph/leveldb/iterator.go
index 1b6771e..9f9b0bf 100644
--- a/graph/leveldb/iterator.go
+++ b/graph/leveldb/iterator.go
@@ -62,7 +62,6 @@ func NewIterator(prefix string, d graph.Direction, value graph.Value, ts *Triple
 		open:           true,
 		ts:             ts,
 	}
-	iterator.BaseInit(&it.Base)
 
 	ok := it.iter.Seek(it.nextPrefix)
 	if !ok {
@@ -155,6 +154,10 @@ func (it *Iterator) Result() graph.Value {
 	return it.result
 }
 
+func (it *Iterator) NextResult() bool {
+	return false
+}
+
 // No subiterators.
 func (it *Iterator) SubIterators() []graph.Iterator {
 	return nil
diff --git a/graph/memstore/iterator.go b/graph/memstore/iterator.go
index be6d1ff..4be57db 100644
--- a/graph/memstore/iterator.go
+++ b/graph/memstore/iterator.go
@@ -56,14 +56,12 @@ func IterateOne(tree *llrb.LLRB, last Int64) Int64 {
 }
 
 func NewLlrbIterator(tree *llrb.LLRB, data string) *Iterator {
-	it := Iterator{
+	return &Iterator{
 		uid:      iterator.NextUID(),
 		tree:     tree,
 		iterLast: Int64(-1),
 		data:     data,
 	}
-	iterator.BaseInit(&it.Base)
-	return &it
 }
 
 func (it *Iterator) UID() uint64 {
@@ -114,6 +112,10 @@ func (it *Iterator) Result() graph.Value {
 	return it.result
 }
 
+func (it *Iterator) NextResult() bool {
+	return false
+}
+
 // No subiterators.
 func (it *Iterator) SubIterators() []graph.Iterator {
 	return nil
diff --git a/graph/mongo/iterator.go b/graph/mongo/iterator.go
index ab752ef..3389e9f 100644
--- a/graph/mongo/iterator.go
+++ b/graph/mongo/iterator.go
@@ -64,7 +64,7 @@ func NewIterator(ts *TripleStore, collection string, d graph.Direction, val grap
 		return nil
 	}
 
-	m := Iterator{
+	return &Iterator{
 		uid:        iterator.NextUID(),
 		name:       name,
 		constraint: constraint,
@@ -76,9 +76,6 @@ func NewIterator(ts *TripleStore, collection string, d graph.Direction, val grap
 		hash:       val.(string),
 		isAll:      false,
 	}
-	iterator.BaseInit(&m.Base)
-
-	return &m
 }
 
 func NewAllIterator(ts *TripleStore, collection string) *Iterator {
@@ -89,7 +86,7 @@ func NewAllIterator(ts *TripleStore, collection string) *Iterator {
 		return nil
 	}
 
-	m := Iterator{
+	return &Iterator{
 		uid:        iterator.NextUID(),
 		ts:         ts,
 		dir:        graph.Any,
@@ -100,9 +97,6 @@ func NewAllIterator(ts *TripleStore, collection string) *Iterator {
 		hash:       "",
 		isAll:      true,
 	}
-	// FIXME(kortschak) Was there supposed to be a BaseInit call here?
-
-	return &m
 }
 
 func (it *Iterator) UID() uint64 {
@@ -171,6 +165,10 @@ func (it *Iterator) Result() graph.Value {
 	return it.result
 }
 
+func (it *Iterator) NextResult() bool {
+	return false
+}
+
 // No subiterators.
 func (it *Iterator) SubIterators() []graph.Iterator {
 	return nil