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graph: add Empty universal iterator for empty returns

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This commit is contained in:
Dan Kortschak
2018-12-13 07:56:04 +10:30
parent fd50e23eae
commit 14c7f9569f
29 changed files with 362 additions and 140 deletions
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113
graph/testgraph/testgraph.go
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@@ -25,16 +25,23 @@ import (
// compared with NaN-awareness, so they may be NaN when there is no edge
// associated with the Weight call.
// BUG(kortschak): The approach of using a nil return for empty sets of nodes
// and edges used prior to the introduction of the graph.Iterator types does
// not interact well with interfaces. For example, it is not possible to simply
// determine that an iterator is empty by calling it.Len without guarding that
// with a nil check. The validity of nil iterators may change depending on the
// outcome of https://github.com/gonum/gonum/issues/614.
func isValidIterator(graph.Iterator) bool {
// TODO(kortschak): Remove nil guards in iterator
// loops and slicer tests if this changes.
return true
func isValidIterator(it graph.Iterator) bool {
return it != nil
}
func checkEmptyIterator(t *testing.T, it graph.Iterator, useEmpty bool) {
if it.Len() != 0 {
return
}
if it != graph.Empty {
if useEmpty {
t.Errorf("unexpected empty iterator: got:%T", it)
return
}
// Only log this since we say that a graph should
// return a graph.Empty when it is empty.
t.Logf("unexpected empty iterator: got:%T", it)
}
}
// A Builder function returns a graph constructed from the nodes, edges and
@@ -68,7 +75,9 @@ type matrixer interface {
// ReturnAllNodes tests the constructed graph for the ability to return all
// the nodes it claims it has used in its construction. This is a check of
// the Nodes method of graph.Graph and the iterator that is returned.
func ReturnAllNodes(t *testing.T, b Builder) {
// If useEmpty is true, graph iterators will be checked for the use of
// graph.Empty if they are empty.
func ReturnAllNodes(t *testing.T, b Builder, useEmpty bool) {
for _, test := range testCases {
g, want, _, _, _, ok := b(test.nodes, test.edges, test.self, test.absent)
if !ok {
@@ -81,8 +90,9 @@ func ReturnAllNodes(t *testing.T, b Builder) {
t.Errorf("invalid iterator for test %q: got:%#v", test.name, it)
continue
}
checkEmptyIterator(t, it, useEmpty)
var got []graph.Node
for it != nil && it.Next() {
for it.Next() {
got = append(got, it.Node())
}
@@ -99,7 +109,9 @@ func ReturnAllNodes(t *testing.T, b Builder) {
// the nodes it claims it has used in its construction using the NodeSlicer
// interface. This is a check of the Nodes method of graph.Graph and the
// iterator that is returned.
func ReturnNodeSlice(t *testing.T, b Builder) {
// If useEmpty is true, graph iterators will be checked for the use of
// graph.Empty if they are empty.
func ReturnNodeSlice(t *testing.T, b Builder, useEmpty bool) {
for _, test := range testCases {
g, want, _, _, _, ok := b(test.nodes, test.edges, test.self, test.absent)
if !ok {
@@ -112,6 +124,7 @@ func ReturnNodeSlice(t *testing.T, b Builder) {
t.Errorf("invalid iterator for test %q: got:%#v", test.name, it)
continue
}
checkEmptyIterator(t, it, useEmpty)
if it == nil {
continue
}
@@ -168,7 +181,9 @@ func NodeExistence(t *testing.T, b Builder) {
// the Edges method of graph.Graph and the iterator that is returned.
// ReturnAllEdges also checks that the edge end nodes exist within the graph,
// checking the Node method of graph.Graph.
func ReturnAllEdges(t *testing.T, b Builder) {
// If useEmpty is true, graph iterators will be checked for the use of
// graph.Empty if they are empty.
func ReturnAllEdges(t *testing.T, b Builder, useEmpty bool) {
for _, test := range testCases {
g, _, want, _, _, ok := b(test.nodes, test.edges, test.self, test.absent)
if !ok {
@@ -184,7 +199,8 @@ func ReturnAllEdges(t *testing.T, b Builder) {
t.Errorf("invalid iterator for test %q: got:%#v", test.name, it)
continue
}
for it != nil && it.Next() {
checkEmptyIterator(t, it, useEmpty)
for it.Next() {
e := it.Edge()
got = append(got, e)
if g.Edge(e.From().ID(), e.To().ID()) == nil {
@@ -212,7 +228,9 @@ func ReturnAllEdges(t *testing.T, b Builder) {
// interface. This is a check of the Edges method of graph.Graph and the
// iterator that is returned. ReturnEdgeSlice also checks that the edge end
// nodes exist within the graph, checking the Node method of graph.Graph.
func ReturnEdgeSlice(t *testing.T, b Builder) {
// If useEmpty is true, graph iterators will be checked for the use of
// graph.Empty if they are empty.
func ReturnEdgeSlice(t *testing.T, b Builder, useEmpty bool) {
for _, test := range testCases {
g, _, want, _, _, ok := b(test.nodes, test.edges, test.self, test.absent)
if !ok {
@@ -228,6 +246,7 @@ func ReturnEdgeSlice(t *testing.T, b Builder) {
t.Errorf("invalid iterator for test %q: got:%#v", test.name, it)
continue
}
checkEmptyIterator(t, it, useEmpty)
if it == nil {
continue
}
@@ -267,7 +286,9 @@ func ReturnEdgeSlice(t *testing.T, b Builder) {
//
// The edges used within and returned by the Builder function should be
// graph.Line. The edge parameter passed to b will contain only graph.Line.
func ReturnAllLines(t *testing.T, b Builder) {
// If useEmpty is true, graph iterators will be checked for the use of
// graph.Empty if they are empty.
func ReturnAllLines(t *testing.T, b Builder, useEmpty bool) {
for _, test := range testCases {
g, _, want, _, _, ok := b(test.nodes, test.edges, test.self, test.absent)
if !ok {
@@ -283,6 +304,7 @@ func ReturnAllLines(t *testing.T, b Builder) {
t.Errorf("invalid iterator for test %q: got:%#v", test.name, it)
continue
}
checkEmptyIterator(t, it, useEmpty)
for _, e := range graph.EdgesOf(it) {
if g.Edge(e.From().ID(), e.To().ID()) == nil {
t.Errorf("missing edge for test %q: %v", test.name, e)
@@ -294,11 +316,11 @@ func ReturnAllLines(t *testing.T, b Builder) {
// and graph.Edges.
switch lit := e.(type) {
case graph.Lines:
for lit != nil && lit.Next() {
for lit.Next() {
got = append(got, lit.Line())
}
case graph.WeightedLines:
for lit != nil && lit.Next() {
for lit.Next() {
got = append(got, lit.WeightedLine())
}
default:
@@ -331,7 +353,9 @@ func ReturnAllLines(t *testing.T, b Builder) {
// The edges used within and returned by the Builder function should be
// graph.WeightedEdge. The edge parameter passed to b will contain only
// graph.WeightedEdge.
func ReturnAllWeightedEdges(t *testing.T, b Builder) {
// If useEmpty is true, graph iterators will be checked for the use of
// graph.Empty if they are empty.
func ReturnAllWeightedEdges(t *testing.T, b Builder, useEmpty bool) {
for _, test := range testCases {
g, _, want, _, _, ok := b(test.nodes, test.edges, test.self, test.absent)
if !ok {
@@ -347,7 +371,8 @@ func ReturnAllWeightedEdges(t *testing.T, b Builder) {
t.Errorf("invalid iterator for test %q: got:%#v", test.name, it)
continue
}
for it != nil && it.Next() {
checkEmptyIterator(t, it, useEmpty)
for it.Next() {
e := it.WeightedEdge()
got = append(got, e)
switch g := g.(type) {
@@ -388,7 +413,9 @@ func ReturnAllWeightedEdges(t *testing.T, b Builder) {
// The edges used within and returned by the Builder function should be
// graph.WeightedEdge. The edge parameter passed to b will contain only
// graph.WeightedEdge.
func ReturnWeightedEdgeSlice(t *testing.T, b Builder) {
// If useEmpty is true, graph iterators will be checked for the use of
// graph.Empty if they are empty.
func ReturnWeightedEdgeSlice(t *testing.T, b Builder, useEmpty bool) {
for _, test := range testCases {
g, _, want, _, _, ok := b(test.nodes, test.edges, test.self, test.absent)
if !ok {
@@ -404,6 +431,7 @@ func ReturnWeightedEdgeSlice(t *testing.T, b Builder) {
t.Errorf("invalid iterator for test %q: got:%#v", test.name, it)
continue
}
checkEmptyIterator(t, it, useEmpty)
s, ok := it.(graph.WeightedEdgeSlicer)
if !ok {
t.Errorf("invalid type for test %T: cannot return weighted edge slice", g)
@@ -442,7 +470,9 @@ func ReturnWeightedEdgeSlice(t *testing.T, b Builder) {
// The edges used within and returned by the Builder function should be
// graph.WeightedLine. The edge parameter passed to b will contain only
// graph.WeightedLine.
func ReturnAllWeightedLines(t *testing.T, b Builder) {
// If useEmpty is true, graph iterators will be checked for the use of
// graph.Empty if they are empty.
func ReturnAllWeightedLines(t *testing.T, b Builder, useEmpty bool) {
for _, test := range testCases {
g, _, want, _, _, ok := b(test.nodes, test.edges, test.self, test.absent)
if !ok {
@@ -458,6 +488,7 @@ func ReturnAllWeightedLines(t *testing.T, b Builder) {
t.Errorf("invalid iterator for test %q: got:%#v", test.name, it)
continue
}
checkEmptyIterator(t, it, useEmpty)
for _, e := range graph.WeightedEdgesOf(it) {
if g.Edge(e.From().ID(), e.To().ID()) == nil {
t.Errorf("missing edge for test %q: %v", test.name, e)
@@ -469,11 +500,11 @@ func ReturnAllWeightedLines(t *testing.T, b Builder) {
// and graph.Edges.
switch lit := e.(type) {
case graph.Lines:
for lit != nil && lit.Next() {
for lit.Next() {
got = append(got, lit.Line())
}
case graph.WeightedLines:
for lit != nil && lit.Next() {
for lit.Next() {
got = append(got, lit.WeightedLine())
}
default:
@@ -602,7 +633,9 @@ func EdgeExistence(t *testing.T, b Builder) {
// within the graph, checking the Node, Edge, EdgeBetween and HasEdgeBetween
// methods of graph.Graph, the EdgeBetween method of graph.Undirected and the
// HasEdgeFromTo method of graph.Directed.
func ReturnAdjacentNodes(t *testing.T, b Builder) {
// If useEmpty is true, graph iterators will be checked for the use of
// graph.Empty if they are empty.
func ReturnAdjacentNodes(t *testing.T, b Builder, useEmpty bool) {
for _, test := range testCases {
g, nodes, edges, _, _, ok := b(test.nodes, test.edges, test.self, test.absent)
if !ok {
@@ -620,7 +653,12 @@ func ReturnAdjacentNodes(t *testing.T, b Builder) {
// Test forward.
u := x
it := g.From(u.ID())
for i := 0; it != nil && it.Next(); i++ {
if !isValidIterator(it) {
t.Errorf("invalid iterator for test %q: got:%#v", test.name, it)
continue
}
checkEmptyIterator(t, it, useEmpty)
for i := 0; it.Next(); i++ {
v := it.Node()
if i == 0 && g.Node(u.ID()) == nil {
t.Errorf("missing from node for test %q: %v", test.name, u.ID())
@@ -645,7 +683,12 @@ func ReturnAdjacentNodes(t *testing.T, b Builder) {
// Test backward.
v := x
it = g.To(v.ID())
for i := 0; it != nil && it.Next(); i++ {
if !isValidIterator(it) {
t.Errorf("invalid iterator for test %q: got:%#v", test.name, it)
continue
}
checkEmptyIterator(t, it, useEmpty)
for i := 0; it.Next(); i++ {
u := it.Node()
if i == 0 && g.Node(v.ID()) == nil {
t.Errorf("missing to node for test %q: %v", test.name, v.ID())
@@ -673,7 +716,12 @@ func ReturnAdjacentNodes(t *testing.T, b Builder) {
case graph.Undirected:
u := x
it := g.From(u.ID())
for i := 0; it != nil && it.Next(); i++ {
if !isValidIterator(it) {
t.Errorf("invalid iterator for test %q: got:%#v", test.name, it)
continue
}
checkEmptyIterator(t, it, useEmpty)
for i := 0; it.Next(); i++ {
v := it.Node()
if i == 0 && g.Node(u.ID()) == nil {
t.Errorf("missing from node for test %q: %v", test.name, u.ID())
@@ -699,7 +747,12 @@ func ReturnAdjacentNodes(t *testing.T, b Builder) {
default:
u := x
it := g.From(u.ID())
for i := 0; it != nil && it.Next(); i++ {
if !isValidIterator(it) {
t.Errorf("invalid iterator for test %q: got:%#v", test.name, it)
continue
}
checkEmptyIterator(t, it, useEmpty)
for i := 0; it.Next(); i++ {
v := it.Node()
if i == 0 && g.Node(u.ID()) == nil {
t.Errorf("missing from node for test %q: %v", test.name, u.ID())