[automata]: improve Graphviz code generation (#126)

moorara · Nov 15, 2022 · 65bc11b · 65bc11b
1 parent b3e149c
commit 65bc11b
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Showing 5 changed files with 187 additions and 72 deletions.
diff --git a/automata/automata.go b/automata/automata.go
@@ -72,6 +72,9 @@ func ToString(s string) String {
 	return res
 }
 
+// doubleKeyMap is a map (symbol table) data structure with two keys.
+type doubleKeyMap[K1, K2, V any] symboltable.OrderedSymbolTable[K1, symboltable.OrderedSymbolTable[K2, V]]
+
 var (
 	cmpState  = generic.NewCompareFunc[State]()
 	cmpSymbol = generic.NewCompareFunc[Symbol]()

diff --git a/automata/dfa.go b/automata/dfa.go
@@ -2,6 +2,7 @@ package automata
 
 import (
 	"fmt"
+	"strings"
 
 	"github.com/moorara/algo/generic"
 	"github.com/moorara/algo/internal/graphviz"
@@ -10,13 +11,11 @@ import (
 	"github.com/moorara/algo/symboltable"
 )
 
-type dfaTrans symboltable.OrderedSymbolTable[State, symboltable.OrderedSymbolTable[Symbol, State]]
-
 // DFA implements a deterministic finite automaton.
 type DFA struct {
 	Start State
 	Final States
-	trans dfaTrans
+	trans doubleKeyMap[State, Symbol, State]
 }
 
 // NewDFA creates a new deterministic finite automaton.
@@ -247,7 +246,7 @@ func (d *DFA) Minimize() *DFA {
 }
 
 // createGroupTrans create a map of states to symbols to the current partition's group representatives (instead of next states).
-func (d *DFA) createGroupTrans(P set.Set[set.Set[State]], G set.Set[State]) dfaTrans {
+func (d *DFA) createGroupTrans(P set.Set[set.Set[State]], G set.Set[State]) doubleKeyMap[State, Symbol, State] {
 	gtrans := symboltable.NewRedBlack[State, symboltable.OrderedSymbolTable[Symbol, State]](cmpState, eqSymbolState)
 
 	for _, s := range G.Members() { // For every state in the current group
@@ -270,7 +269,7 @@ func (d *DFA) createGroupTrans(P set.Set[set.Set[State]], G set.Set[State]) dfaT
 }
 
 // populateSubgroups creates new subgroups based on the transition map of a group and add them to the new partition.
-func populateSubgroups(Pnew set.Set[set.Set[State]], gtrans dfaTrans) {
+func populateSubgroups(Pnew set.Set[set.Set[State]], gtrans doubleKeyMap[State, Symbol, State]) {
 	eqFunc := func(a, b State) bool { return a == b }
 
 	kvs := gtrans.KeyValues()
@@ -344,12 +343,36 @@ func (d *DFA) Graphviz() string {
 		graph.AddNode(graphviz.NewNode(name, "", label, "", "", shape, "", ""))
 	}
 
+	// Group all the transitions with the same states and combine their symbols into one label
+
+	var edges doubleKeyMap[State, State, []string]
+	edges = symboltable.NewRedBlack[State, symboltable.OrderedSymbolTable[State, []string]](cmpState, nil)
+
 	for _, kv := range d.trans.KeyValues() {
-		from := fmt.Sprintf("%d", kv.Key)
+		from := kv.Key
+		tab, exist := edges.Get(from)
+		if !exist {
+			tab = symboltable.NewRedBlack[State, []string](cmpState, nil)
+			edges.Put(from, tab)
+		}
 
 		for _, kv := range kv.Val.KeyValues() {
-			label := string(kv.Key)
-			to := fmt.Sprintf("%d", kv.Val)
+			symbol, to := string(kv.Key), kv.Val
+			vals, _ := tab.Get(to)
+			vals = append(vals, symbol)
+			tab.Put(to, vals)
+		}
+	}
+
+	for _, kv := range edges.KeyValues() {
+		from := kv.Key
+		for _, kv := range kv.Val.KeyValues() {
+			from := fmt.Sprintf("%d", from)
+			to := fmt.Sprintf("%d", kv.Key)
+			symbols := kv.Val
+
+			sort.Quick(symbols, generic.NewCompareFunc[string]())
+			label := strings.Join(symbols, ",")
 
 			graph.AddEdge(graphviz.NewEdge(from, to, graphviz.EdgeTypeDirected, "", label, "", "", "", ""))
 		}

diff --git a/automata/dfa_test.go b/automata/dfa_test.go
@@ -60,7 +60,13 @@ func getTestDFAs() []*DFA {
 	d3.Add(3, 'a', 1)
 	d3.Add(3, 'b', 0)
 
-	return []*DFA{d0, d1, d2, d3}
+	d4 := NewDFA(0, States{1})
+	d4.Add(0, 'a', 1)
+	d4.Add(0, 'b', 1)
+	d4.Add(1, 'a', 1)
+	d4.Add(1, 'b', 1)
+
+	return []*DFA{d0, d1, d2, d3, d4}
 }
 
 func TestNewDFA(t *testing.T) {
@@ -392,9 +398,35 @@ func TestDFA_Graphviz(t *testing.T) {
 		expectedGraphviz string
 	}{
 		{
-			name: "Empty",
-			d:    NewDFA(0, States{1}),
-			expectedGraphviz: `digraph "DFA" {
+			name:             "Empty",
+			d:                NewDFA(0, States{1}),
+			expectedGraphviz: dfaEmpty,
+		},
+		{
+			name:             "First",
+			d:                dfas[0],
+			expectedGraphviz: dfa01,
+		},
+		{
+			name:             "Second",
+			d:                dfas[1],
+			expectedGraphviz: dfa02,
+		},
+		{
+			name:             "Third",
+			d:                dfas[4],
+			expectedGraphviz: dfa03,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			assert.Equal(t, tc.expectedGraphviz, tc.d.Graphviz())
+		})
+	}
+}
+
+var dfaEmpty = `digraph "DFA" {
   rankdir=LR;
   concentrate=false;
   node [];
@@ -404,12 +436,9 @@ func TestDFA_Graphviz(t *testing.T) {
   1 [label="1", shape=doublecircle];
 
   start -> 0 [];
-}`,
-		},
-		{
-			name: "First",
-			d:    dfas[0],
-			expectedGraphviz: `digraph "DFA" {
+}`
+
+var dfa01 = `digraph "DFA" {
   rankdir=LR;
   concentrate=false;
   node [];
@@ -421,20 +450,17 @@ func TestDFA_Graphviz(t *testing.T) {
   3 [label="3", shape=doublecircle];
 
   start -> 0 [];
-  0 -> 1 [label="a"];
   0 -> 0 [label="b"];
+  0 -> 1 [label="a"];
   1 -> 1 [label="a"];
   1 -> 2 [label="b"];
   2 -> 1 [label="a"];
   2 -> 3 [label="b"];
-  3 -> 1 [label="a"];
   3 -> 0 [label="b"];
-}`,
-		},
-		{
-			name: "Second",
-			d:    dfas[1],
-			expectedGraphviz: `digraph "DFA" {
+  3 -> 1 [label="a"];
+}`
+
+var dfa02 = `digraph "DFA" {
   rankdir=LR;
   concentrate=false;
   node [];
@@ -457,13 +483,18 @@ func TestDFA_Graphviz(t *testing.T) {
   3 -> 4 [label="b"];
   4 -> 1 [label="a"];
   4 -> 2 [label="b"];
-}`,
-		},
-	}
+}`
 
-	for _, tc := range tests {
-		t.Run(tc.name, func(t *testing.T) {
-			assert.Equal(t, tc.expectedGraphviz, tc.d.Graphviz())
-		})
-	}
-}
+var dfa03 = `digraph "DFA" {
+  rankdir=LR;
+  concentrate=false;
+  node [];
+
+  start [style=invis];
+  0 [label="0", shape=circle];
+  1 [label="1", shape=doublecircle];
+
+  start -> 0 [];
+  0 -> 1 [label="a,b"];
+  1 -> 1 [label="a,b"];
+}`
diff --git a/automata/nfa.go b/automata/nfa.go
@@ -2,6 +2,7 @@ package automata
 
 import (
 	"fmt"
+	"strings"
 
 	"github.com/moorara/algo/generic"
 	"github.com/moorara/algo/internal/graphviz"
@@ -10,13 +11,11 @@ import (
 	"github.com/moorara/algo/symboltable"
 )
 
-type nfaTrans symboltable.OrderedSymbolTable[State, symboltable.OrderedSymbolTable[Symbol, States]]
-
 // NFA implements a non-deterministic finite automaton.
 type NFA struct {
 	Start State
 	Final States
-	trans nfaTrans
+	trans doubleKeyMap[State, Symbol, States]
 }
 
 // NewNFA creates a new non-deterministic finite automaton.
@@ -276,24 +275,48 @@ func (n *NFA) Graphviz() string {
 		graph.AddNode(graphviz.NewNode(name, "", label, "", "", shape, "", ""))
 	}
 
+	// Group all the transitions with the same states and combine their symbols into one label
+
+	var edges doubleKeyMap[State, State, []string]
+	edges = symboltable.NewRedBlack[State, symboltable.OrderedSymbolTable[State, []string]](cmpState, nil)
+
 	for _, kv := range n.trans.KeyValues() {
-		from := fmt.Sprintf("%d", kv.Key)
+		from := kv.Key
+		tab, exist := edges.Get(from)
+		if !exist {
+			tab = symboltable.NewRedBlack[State, []string](cmpState, nil)
+			edges.Put(from, tab)
+		}
 
 		for _, kv := range kv.Val.KeyValues() {
-			var label string
-			if symbol := kv.Key; symbol == E {
-				label = "ε"
+			var symbol string
+			if kv.Key == E {
+				symbol = "ε"
 			} else {
-				label = string(symbol)
+				symbol = string(kv.Key)
 			}
 
-			for _, s := range kv.Val {
-				to := fmt.Sprintf("%d", s)
-
-				graph.AddEdge(graphviz.NewEdge(from, to, graphviz.EdgeTypeDirected, "", label, "", "", "", ""))
+			for _, to := range kv.Val {
+				vals, _ := tab.Get(to)
+				vals = append(vals, symbol)
+				tab.Put(to, vals)
 			}
 		}
 	}
 
+	for _, kv := range edges.KeyValues() {
+		from := kv.Key
+		for _, kv := range kv.Val.KeyValues() {
+			from := fmt.Sprintf("%d", from)
+			to := fmt.Sprintf("%d", kv.Key)
+			symbols := kv.Val
+
+			sort.Quick(symbols, generic.NewCompareFunc[string]())
+			label := strings.Join(symbols, ",")
+
+			graph.AddEdge(graphviz.NewEdge(from, to, graphviz.EdgeTypeDirected, "", label, "", "", "", ""))
+		}
+	}
+
 	return graph.DotCode()
 }