graph,graph/{encoding/dot,internal/set,topo,traverse}: remove intsets…

… imports

graph/encoding/dot/decode.go

@@ -7,11 +7,10 @@ package dot
 import (
 	"fmt"
 
-	"golang.org/x/tools/container/intsets"
-
 	"gonum.org/v1/gonum/graph"
 	"gonum.org/v1/gonum/graph/formats/dot"
 	"gonum.org/v1/gonum/graph/formats/dot/ast"
+	"gonum.org/v1/gonum/graph/internal/set"
 )
 
 // Builder is a graph that can have user-defined nodes and edges added.
@@ -267,14 +266,14 @@ func (gen *generator) popSubgraph() []graph.Node {
 // unique returns the set of unique nodes contained within ns.
 func unique(ns []graph.Node) []graph.Node {
 	var nodes []graph.Node
-	var set intsets.Sparse
+	seen := make(set.Ints)
 	for _, n := range ns {
 		id := n.ID()
-		if set.Has(id) {
+		if seen.Has(id) {
 			// skip duplicate node
 			continue
 		}
-		set.Insert(id)
+		seen.Add(id)
 		nodes = append(nodes, n)
 	}
 	return nodes

graph/encoding/dot/dot_test.go

@@ -12,14 +12,14 @@ import (
 	"gonum.org/v1/gonum/graph/simple"
 )
 
-// set is an integer set.
-type set map[int]struct{}
+// intset is an integer set.
+type intset map[int]struct{}
 
-func linksTo(i ...int) set {
+func linksTo(i ...int) intset {
 	if len(i) == 0 {
 		return nil
 	}
-	s := make(set)
+	s := make(intset)
 	for _, v := range i {
 		s[v] = struct{}{}
 	}
@@ -29,7 +29,7 @@ func linksTo(i ...int) set {
 var (
 	// Example graph from http://en.wikipedia.org/wiki/File:PageRanks-Example.svg 16:17, 8 July 2009
 	// Node identities are rewritten here to use integers from 0 to match with the DOT output.
-	pageRankGraph = []set{
+	pageRankGraph = []intset{
 		0:  nil,
 		1:  linksTo(2),
 		2:  linksTo(1),
@@ -44,7 +44,7 @@ var (
 	}
 
 	// Example graph from http://en.wikipedia.org/w/index.php?title=PageRank&oldid=659286279#Power_Method
-	powerMethodGraph = []set{
+	powerMethodGraph = []intset{
 		0: linksTo(1, 2),
 		1: linksTo(3),
 		2: linksTo(3, 4),
@@ -53,7 +53,7 @@ var (
 	}
 )
 
-func directedGraphFrom(g []set) graph.Directed {
+func directedGraphFrom(g []intset) graph.Directed {
 	dg := simple.NewDirectedGraph(0, math.Inf(1))
 	for u, e := range g {
 		for v := range e {
@@ -63,7 +63,7 @@ func directedGraphFrom(g []set) graph.Directed {
 	return dg
 }
 
-func undirectedGraphFrom(g []set) graph.Graph {
+func undirectedGraphFrom(g []intset) graph.Graph {
 	dg := simple.NewUndirectedGraph(0, math.Inf(1))
 	for u, e := range g {
 		for v := range e {
@@ -83,7 +83,7 @@ type namedNode struct {
 func (n namedNode) ID() int       { return n.id }
 func (n namedNode) DOTID() string { return n.name }
 
-func directedNamedIDGraphFrom(g []set) graph.Directed {
+func directedNamedIDGraphFrom(g []intset) graph.Directed {
 	dg := simple.NewDirectedGraph(0, math.Inf(1))
 	for u, e := range g {
 		nu := namedNode{id: u, name: alpha[u : u+1]}
@@ -95,7 +95,7 @@ func directedNamedIDGraphFrom(g []set) graph.Directed {
 	return dg
 }
 
-func undirectedNamedIDGraphFrom(g []set) graph.Graph {
+func undirectedNamedIDGraphFrom(g []intset) graph.Graph {
 	dg := simple.NewUndirectedGraph(0, math.Inf(1))
 	for u, e := range g {
 		nu := namedNode{id: u, name: alpha[u : u+1]}
@@ -116,7 +116,7 @@ type attrNode struct {
 func (n attrNode) ID() int                    { return n.id }
 func (n attrNode) DOTAttributes() []Attribute { return n.attr }
 
-func directedNodeAttrGraphFrom(g []set, attr [][]Attribute) graph.Directed {
+func directedNodeAttrGraphFrom(g []intset, attr [][]Attribute) graph.Directed {
 	dg := simple.NewDirectedGraph(0, math.Inf(1))
 	for u, e := range g {
 		var at []Attribute
@@ -135,7 +135,7 @@ func directedNodeAttrGraphFrom(g []set, attr [][]Attribute) graph.Directed {
 	return dg
 }
 
-func undirectedNodeAttrGraphFrom(g []set, attr [][]Attribute) graph.Graph {
+func undirectedNodeAttrGraphFrom(g []intset, attr [][]Attribute) graph.Graph {
 	dg := simple.NewUndirectedGraph(0, math.Inf(1))
 	for u, e := range g {
 		var at []Attribute
@@ -164,7 +164,7 @@ func (n namedAttrNode) ID() int                    { return n.id }
 func (n namedAttrNode) DOTID() string              { return n.name }
 func (n namedAttrNode) DOTAttributes() []Attribute { return n.attr }
 
-func directedNamedIDNodeAttrGraphFrom(g []set, attr [][]Attribute) graph.Directed {
+func directedNamedIDNodeAttrGraphFrom(g []intset, attr [][]Attribute) graph.Directed {
 	dg := simple.NewDirectedGraph(0, math.Inf(1))
 	for u, e := range g {
 		var at []Attribute
@@ -183,7 +183,7 @@ func directedNamedIDNodeAttrGraphFrom(g []set, attr [][]Attribute) graph.Directe
 	return dg
 }
 
-func undirectedNamedIDNodeAttrGraphFrom(g []set, attr [][]Attribute) graph.Graph {
+func undirectedNamedIDNodeAttrGraphFrom(g []intset, attr [][]Attribute) graph.Graph {
 	dg := simple.NewUndirectedGraph(0, math.Inf(1))
 	for u, e := range g {
 		var at []Attribute
@@ -213,7 +213,7 @@ func (e attrEdge) To() graph.Node             { return e.to }
 func (e attrEdge) Weight() float64            { return 0 }
 func (e attrEdge) DOTAttributes() []Attribute { return e.attr }
 
-func directedEdgeAttrGraphFrom(g []set, attr map[edge][]Attribute) graph.Directed {
+func directedEdgeAttrGraphFrom(g []intset, attr map[edge][]Attribute) graph.Directed {
 	dg := simple.NewDirectedGraph(0, math.Inf(1))
 	for u, e := range g {
 		for v := range e {
@@ -223,7 +223,7 @@ func directedEdgeAttrGraphFrom(g []set, attr map[edge][]Attribute) graph.Directe
 	return dg
 }
 
-func undirectedEdgeAttrGraphFrom(g []set, attr map[edge][]Attribute) graph.Graph {
+func undirectedEdgeAttrGraphFrom(g []intset, attr map[edge][]Attribute) graph.Graph {
 	dg := simple.NewUndirectedGraph(0, math.Inf(1))
 	for u, e := range g {
 		for v := range e {
@@ -263,7 +263,7 @@ func (e portedEdge) ToPort() (port, compass string) {
 	return e.toPort, e.toCompass
 }
 
-func directedPortedAttrGraphFrom(g []set, attr [][]Attribute, ports map[edge]portedEdge) graph.Directed {
+func directedPortedAttrGraphFrom(g []intset, attr [][]Attribute, ports map[edge]portedEdge) graph.Directed {
 	dg := simple.NewDirectedGraph(0, math.Inf(1))
 	for u, e := range g {
 		var at []Attribute
@@ -284,7 +284,7 @@ func directedPortedAttrGraphFrom(g []set, attr [][]Attribute, ports map[edge]por
 	return dg
 }
 
-func undirectedPortedAttrGraphFrom(g []set, attr [][]Attribute, ports map[edge]portedEdge) graph.Graph {
+func undirectedPortedAttrGraphFrom(g []intset, attr [][]Attribute, ports map[edge]portedEdge) graph.Graph {
 	dg := simple.NewUndirectedGraph(0, math.Inf(1))
 	for u, e := range g {
 		var at []Attribute
@@ -325,7 +325,7 @@ type structuredGraph struct {
 	sub []Graph
 }
 
-func undirectedStructuredGraphFrom(c []edge, g ...[]set) graph.Graph {
+func undirectedStructuredGraphFrom(c []edge, g ...[]intset) graph.Graph {
 	s := &structuredGraph{UndirectedGraph: simple.NewUndirectedGraph(0, math.Inf(1))}
 	var base int
 	for i, sg := range g {
@@ -366,7 +366,7 @@ func (g subGraph) Subgraph() graph.Graph {
 	return namedGraph{id: g.id, Graph: g.Graph}
 }
 
-func undirectedSubGraphFrom(g []set, s map[int][]set) graph.Graph {
+func undirectedSubGraphFrom(g []intset, s map[int][]intset) graph.Graph {
 	var base int
 	subs := make(map[int]subGraph)
 	for i, sg := range s {
@@ -1264,7 +1264,7 @@ var encodeTests = []struct {
 
 	// Handling subgraphs.
 	{
-		g: undirectedSubGraphFrom(pageRankGraph, map[int][]set{2: powerMethodGraph}),
+		g: undirectedSubGraphFrom(pageRankGraph, map[int][]intset{2: powerMethodGraph}),
 
 		want: `graph {
 	// Node definitions.
@@ -1315,7 +1315,7 @@ var encodeTests = []struct {
 	},
 	{
 		name:   "H",
-		g:      undirectedSubGraphFrom(pageRankGraph, map[int][]set{1: powerMethodGraph}),
+		g:      undirectedSubGraphFrom(pageRankGraph, map[int][]intset{1: powerMethodGraph}),
 		strict: true,
 
 		want: `strict graph H {

graph/internal/set/same.go

@@ -16,3 +16,12 @@ import "unsafe"
 func same(a, b Nodes) bool {
 	return *(*uintptr)(unsafe.Pointer(&a)) == *(*uintptr)(unsafe.Pointer(&b))
 }
+
+// intsSame determines whether two sets are backed by the same store. In the
+// current implementation using hash maps it makes use of the fact that
+// hash maps are passed as a pointer to a runtime Hmap struct. A map is
+// not seen by the runtime as a pointer though, so we use unsafe to get
+// the maps' pointer values to compare.
+func intsSame(a, b Ints) bool {
+	return *(*uintptr)(unsafe.Pointer(&a)) == *(*uintptr)(unsafe.Pointer(&b))
+}

graph/internal/set/set.go

@@ -34,6 +34,26 @@ func (s Ints) Count() int {
 	return len(s)
 }
 
+// IntsEqual reports set equality between the parameters. Sets are equal if
+// and only if they have the same elements.
+func IntsEqual(a, b Ints) bool {
+	if intsSame(a, b) {
+		return true
+	}
+
+	if len(a) != len(b) {
+		return false
+	}
+
+	for e := range a {
+		if _, ok := b[e]; !ok {
+			return false
+		}
+	}
+
+	return true
+}
+
 // Nodes is a set of nodes keyed in their integer identifiers.
 type Nodes map[int]graph.Node
 

graph/topo/tarjan.go

@@ -8,10 +8,9 @@ import (
 	"fmt"
 	"sort"
 
-	"golang.org/x/tools/container/intsets"
-
 	"gonum.org/v1/gonum/graph"
 	"gonum.org/v1/gonum/graph/internal/ordered"
+	"gonum.org/v1/gonum/graph/internal/set"
 )
 
 // Unorderable is an error containing sets of unorderable graph.Nodes.
@@ -122,7 +121,7 @@ func tarjanSCCstabilized(g graph.Directed, order func([]graph.Node)) [][]graph.N
 
 		indexTable: make(map[int]int, len(nodes)),
 		lowLink:    make(map[int]int, len(nodes)),
-		onStack:    &intsets.Sparse{},
+		onStack:    make(set.Ints),
 	}
 	for _, v := range nodes {
 		if t.indexTable[v.ID()] == 0 {
@@ -143,7 +142,7 @@ type tarjan struct {
 	index      int
 	indexTable map[int]int
 	lowLink    map[int]int
-	onStack    *intsets.Sparse
+	onStack    set.Ints
 
 	stack []graph.Node
 
@@ -160,7 +159,7 @@ func (t *tarjan) strongconnect(v graph.Node) {
 	t.indexTable[vID] = t.index
 	t.lowLink[vID] = t.index
 	t.stack = append(t.stack, v)
-	t.onStack.Insert(vID)
+	t.onStack.Add(vID)
 
 	// Consider successors of v.
 	for _, w := range t.succ(v) {

graph/traverse/traverse.go

@@ -6,18 +6,17 @@
 package traverse // import "gonum.org/v1/gonum/graph/traverse"
 
 import (
-	"golang.org/x/tools/container/intsets"
-
 	"gonum.org/v1/gonum/graph"
 	"gonum.org/v1/gonum/graph/internal/linear"
+	"gonum.org/v1/gonum/graph/internal/set"
 )
 
 // BreadthFirst implements stateful breadth-first graph traversal.
 type BreadthFirst struct {
 	EdgeFilter func(graph.Edge) bool
 	Visit      func(u, v graph.Node)
 	queue      linear.NodeQueue
-	visited    *intsets.Sparse
+	visited    set.Ints
 }
 
 // Walk performs a breadth-first traversal of the graph g starting from the given node,
@@ -27,10 +26,10 @@ type BreadthFirst struct {
 // non-nil, it is called with the nodes joined by each followed edge.
 func (b *BreadthFirst) Walk(g graph.Graph, from graph.Node, until func(n graph.Node, d int) bool) graph.Node {
 	if b.visited == nil {
-		b.visited = &intsets.Sparse{}
+		b.visited = make(set.Ints)
 	}
 	b.queue.Enqueue(from)
-	b.visited.Insert(from.ID())
+	b.visited.Add(from.ID())
 
 	var (
 		depth     int
@@ -52,7 +51,7 @@ func (b *BreadthFirst) Walk(g graph.Graph, from graph.Node, until func(n graph.N
 			if b.Visit != nil {
 				b.Visit(t, n)
 			}
-			b.visited.Insert(n.ID())
+			b.visited.Add(n.ID())
 			children++
 			b.queue.Enqueue(n)
 		}
@@ -93,23 +92,21 @@ func (b *BreadthFirst) WalkAll(g graph.Undirected, before, after func(), during
 
 // Visited returned whether the node n was visited during a traverse.
 func (b *BreadthFirst) Visited(n graph.Node) bool {
-	return b.visited != nil && b.visited.Has(n.ID())
+	return b.visited.Has(n.ID())
 }
 
 // Reset resets the state of the traverser for reuse.
 func (b *BreadthFirst) Reset() {
 	b.queue.Reset()
-	if b.visited != nil {
-		b.visited.Clear()
-	}
+	b.visited = nil
 }
 
 // DepthFirst implements stateful depth-first graph traversal.
 type DepthFirst struct {
 	EdgeFilter func(graph.Edge) bool
 	Visit      func(u, v graph.Node)
 	stack      linear.NodeStack
-	visited    *intsets.Sparse
+	visited    set.Ints
 }
 
 // Walk performs a depth-first traversal of the graph g starting from the given node,
@@ -119,10 +116,10 @@ type DepthFirst struct {
 // is called with the nodes joined by each followed edge.
 func (d *DepthFirst) Walk(g graph.Graph, from graph.Node, until func(graph.Node) bool) graph.Node {
 	if d.visited == nil {
-		d.visited = &intsets.Sparse{}
+		d.visited = make(set.Ints)
 	}
 	d.stack.Push(from)
-	d.visited.Insert(from.ID())
+	d.visited.Add(from.ID())
 
 	for d.stack.Len() > 0 {
 		t := d.stack.Pop()
@@ -139,7 +136,7 @@ func (d *DepthFirst) Walk(g graph.Graph, from graph.Node, until func(graph.Node)
 			if d.Visit != nil {
 				d.Visit(t, n)
 			}
-			d.visited.Insert(n.ID())
+			d.visited.Add(n.ID())
 			d.stack.Push(n)
 		}
 	}
@@ -174,13 +171,11 @@ func (d *DepthFirst) WalkAll(g graph.Undirected, before, after func(), during fu
 
 // Visited returned whether the node n was visited during a traverse.
 func (d *DepthFirst) Visited(n graph.Node) bool {
-	return d.visited != nil && d.visited.Has(n.ID())
+	return d.visited.Has(n.ID())
 }
 
 // Reset resets the state of the traverser for reuse.
 func (d *DepthFirst) Reset() {
 	d.stack = d.stack[:0]
-	if d.visited != nil {
-		d.visited.Clear()
-	}
+	d.visited = nil
 }