4 files changed, 2846 insertions, 0 deletions

diff --git a/tests/unit/urubu/grammar/lexical.go b/tests/unit/urubu/grammar/lexical.go
new file mode 100644
index 0000000..b621cd2
--- /dev/null
+++ b/tests/unit/urubu/grammar/lexical.go
@@ -0,0 +1,338 @@
+package lexical
+
+import (
+	"encoding/json"
+	"fmt"
+	"testing"
+
+	spec "urubu/spec/grammar"
+)
+
+func TestLexSpec_Validate(t *testing.T) {
+	// We expect that the spelling inconsistency error will occur.
+	spec := &LexSpec{
+		Entries: []*LexEntry{
+			{
+				Modes: []spec.LexModeName{
+					// 'Default' is the spelling inconsistency because 'default' is predefined.
+					"Default",
+				},
+				Kind:    "foo",
+				Pattern: "foo",
+			},
+		},
+	}
+	err := spec.Validate()
+	if err == nil {
+		t.Fatalf("expected error didn't occur")
+	}
+}
+
+func TestSnakeCaseToUpperCamelCase(t *testing.T) {
+	tests := []struct {
+		snake string
+		camel string
+	}{
+		{
+			snake: "foo",
+			camel: "Foo",
+		},
+		{
+			snake: "foo_bar",
+			camel: "FooBar",
+		},
+		{
+			snake: "foo_bar_baz",
+			camel: "FooBarBaz",
+		},
+		{
+			snake: "Foo",
+			camel: "Foo",
+		},
+		{
+			snake: "fooBar",
+			camel: "FooBar",
+		},
+		{
+			snake: "FOO",
+			camel: "FOO",
+		},
+		{
+			snake: "FOO_BAR",
+			camel: "FOOBAR",
+		},
+		{
+			snake: "_foo_bar_",
+			camel: "FooBar",
+		},
+		{
+			snake: "___foo___bar___",
+			camel: "FooBar",
+		},
+	}
+	for _, tt := range tests {
+		c := SnakeCaseToUpperCamelCase(tt.snake)
+		if c != tt.camel {
+			t.Errorf("unexpected string; want: %v, got: %v", tt.camel, c)
+		}
+	}
+}
+
+func TestFindSpellingInconsistencies(t *testing.T) {
+	tests := []struct {
+		ids        []string
+		duplicated [][]string
+	}{
+		{
+			ids:        []string{"foo", "foo"},
+			duplicated: nil,
+		},
+		{
+			ids:        []string{"foo", "Foo"},
+			duplicated: [][]string{{"Foo", "foo"}},
+		},
+		{
+			ids:        []string{"foo", "foo", "Foo"},
+			duplicated: [][]string{{"Foo", "foo"}},
+		},
+		{
+			ids:        []string{"foo_bar_baz", "FooBarBaz"},
+			duplicated: [][]string{{"FooBarBaz", "foo_bar_baz"}},
+		},
+		{
+			ids:        []string{"foo", "Foo", "bar", "Bar"},
+			duplicated: [][]string{{"Bar", "bar"}, {"Foo", "foo"}},
+		},
+		{
+			ids:        []string{"foo", "Foo", "bar", "Bar", "baz", "bra"},
+			duplicated: [][]string{{"Bar", "bar"}, {"Foo", "foo"}},
+		},
+	}
+	for i, tt := range tests {
+		t.Run(fmt.Sprintf("#%v", i), func(t *testing.T) {
+			duplicated := FindSpellingInconsistencies(tt.ids)
+			if len(duplicated) != len(tt.duplicated) {
+				t.Fatalf("unexpected IDs; want: %#v, got: %#v", tt.duplicated, duplicated)
+			}
+			for i, dupIDs := range duplicated {
+				if len(dupIDs) != len(tt.duplicated[i]) {
+					t.Fatalf("unexpected IDs; want: %#v, got: %#v", tt.duplicated[i], dupIDs)
+				}
+				for j, id := range dupIDs {
+					if id != tt.duplicated[i][j] {
+						t.Fatalf("unexpected IDs; want: %#v, got: %#v", tt.duplicated[i], dupIDs)
+					}
+				}
+			}
+		})
+	}
+}
+
+func TestCompile(t *testing.T) {
+	tests := []struct {
+		Caption string
+		Spec    string
+		Err     bool
+	}{
+		{
+			Caption: "allow duplicates names between fragments and non-fragments",
+			Spec: `
+{
+    "name": "test",
+    "entries": [
+        {
+            "kind": "a2z",
+            "pattern": "\\f{a2z}"
+        },
+        {
+            "fragment": true,
+            "kind": "a2z",
+            "pattern": "[a-z]"
+        }
+    ]
+}
+`,
+		},
+		{
+			Caption: "don't allow duplicates names in non-fragments",
+			Spec: `
+{
+    "name": "test",
+    "entries": [
+        {
+            "kind": "a2z",
+            "pattern": "a|b|c|d|e|f|g|h|i|j|k|l|m|n|o|p|q|r|s|t|u|v|w|x|y|z"
+        },
+        {
+            "kind": "a2z",
+            "pattern": "[a-z]"
+        }
+    ]
+}
+`,
+			Err: true,
+		},
+		{
+			Caption: "don't allow duplicates names in fragments",
+			Spec: `
+{
+    "name": "test",
+    "entries": [
+        {
+            "kind": "a2z",
+            "pattern": "\\f{a2z}"
+        },
+        {
+            "fragments": true,
+            "kind": "a2z",
+            "pattern": "a|b|c|d|e|f|g|h|i|j|k|l|m|n|o|p|q|r|s|t|u|v|w|x|y|z"
+        },
+        {
+            "fragments": true,
+            "kind": "a2z",
+            "pattern": "[a-z]"
+        }
+    ]
+}
+`,
+			Err: true,
+		},
+		{
+			Caption: "don't allow kind names in the same mode to contain spelling inconsistencies",
+			Spec: `
+{
+    "name": "test",
+    "entries": [
+        {
+            "kind": "foo_1",
+            "pattern": "foo_1"
+        },
+        {
+            "kind": "foo1",
+            "pattern": "foo1"
+        }
+    ]
+}
+`,
+			Err: true,
+		},
+		{
+			Caption: "don't allow kind names across modes to contain spelling inconsistencies",
+			Spec: `
+{
+    "name": "test",
+    "entries": [
+        {
+            "modes": ["default"],
+            "kind": "foo_1",
+            "pattern": "foo_1"
+        },
+        {
+            "modes": ["other_mode"],
+            "kind": "foo1",
+            "pattern": "foo1"
+        }
+    ]
+}
+`,
+			Err: true,
+		},
+		{
+			Caption: "don't allow mode names to contain spelling inconsistencies",
+			Spec: `
+{
+    "name": "test",
+    "entries": [
+        {
+            "modes": ["foo_1"],
+            "kind": "a",
+            "pattern": "a"
+        },
+        {
+            "modes": ["foo1"],
+            "kind": "b",
+            "pattern": "b"
+        }
+    ]
+}
+`,
+			Err: true,
+		},
+		{
+			Caption: "allow fragment names in the same mode to contain spelling inconsistencies because fragments will not appear in output files",
+			Spec: `
+{
+    "name": "test",
+    "entries": [
+        {
+            "kind": "a",
+            "pattern": "a"
+        },
+        {
+            "fragment": true,
+            "kind": "foo_1",
+            "pattern": "foo_1"
+        },
+        {
+            "fragment": true,
+            "kind": "foo1",
+            "pattern": "foo1"
+        }
+    ]
+}
+`,
+		},
+		{
+			Caption: "allow fragment names across modes to contain spelling inconsistencies because fragments will not appear in output files",
+			Spec: `
+{
+    "name": "test",
+    "entries": [
+        {
+            "modes": ["default"],
+            "kind": "a",
+            "pattern": "a"
+        },
+        {
+            "modes": ["default"],
+            "fragment": true,
+            "kind": "foo_1",
+            "pattern": "foo_1"
+        },
+        {
+            "modes": ["other_mode"],
+            "fragment": true,
+            "kind": "foo1",
+            "pattern": "foo1"
+        }
+    ]
+}
+`,
+		},
+	}
+	for i, tt := range tests {
+		t.Run(fmt.Sprintf("#%v %s", i, tt.Caption), func(t *testing.T) {
+			lspec := &LexSpec{}
+			err := json.Unmarshal([]byte(tt.Spec), lspec)
+			if err != nil {
+				t.Fatalf("%v", err)
+			}
+			clspec, err, _ := Compile(lspec, CompressionLevelMin)
+			if tt.Err {
+				if err == nil {
+					t.Fatalf("expected an error")
+				}
+				if clspec != nil {
+					t.Fatalf("Compile function mustn't return a compiled specification")
+				}
+			} else {
+				if err != nil {
+					t.Fatalf("unexpected error: %v", err)
+				}
+				if clspec == nil {
+					t.Fatalf("Compile function must return a compiled specification")
+				}
+			}
+		})
+	}
+}
diff --git a/tests/unit/urubu/grammar/lexical/dfa.go b/tests/unit/urubu/grammar/lexical/dfa.go
new file mode 100644
index 0000000..1a3e16a
--- /dev/null
+++ b/tests/unit/urubu/grammar/lexical/dfa.go
@@ -0,0 +1,442 @@
+package dfa
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"urubu/grammar/lexical/parser"
+	spec "urubu/spec/grammar"
+)
+
+func TestGenDFA(t *testing.T) {
+	p := parser.NewParser(spec.LexKindName("test"), strings.NewReader("(a|b)*abb"))
+	cpt, err := p.Parse()
+	if err != nil {
+		t.Fatal(err)
+	}
+	bt, symTab, err := ConvertCPTreeToByteTree(map[spec.LexModeKindID]parser.CPTree{
+		spec.LexModeKindIDMin: cpt,
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	dfa := GenDFA(bt, symTab)
+	if dfa == nil {
+		t.Fatalf("DFA is nil")
+	}
+
+	symPos := func(n uint16) symbolPosition {
+		pos, err := newSymbolPosition(n, false)
+		if err != nil {
+			panic(err)
+		}
+		return pos
+	}
+
+	endPos := func(n uint16) symbolPosition {
+		pos, err := newSymbolPosition(n, true)
+		if err != nil {
+			panic(err)
+		}
+		return pos
+	}
+
+	s0 := newSymbolPositionSet().add(symPos(1)).add(symPos(2)).add(symPos(3))
+	s1 := newSymbolPositionSet().add(symPos(1)).add(symPos(2)).add(symPos(3)).add(symPos(4))
+	s2 := newSymbolPositionSet().add(symPos(1)).add(symPos(2)).add(symPos(3)).add(symPos(5))
+	s3 := newSymbolPositionSet().add(symPos(1)).add(symPos(2)).add(symPos(3)).add(endPos(6))
+
+	rune2Int := func(char rune, index int) uint8 {
+		return uint8([]byte(string(char))[index])
+	}
+
+	tranS0 := [256]string{}
+	tranS0[rune2Int('a', 0)] = s1.hash()
+	tranS0[rune2Int('b', 0)] = s0.hash()
+
+	tranS1 := [256]string{}
+	tranS1[rune2Int('a', 0)] = s1.hash()
+	tranS1[rune2Int('b', 0)] = s2.hash()
+
+	tranS2 := [256]string{}
+	tranS2[rune2Int('a', 0)] = s1.hash()
+	tranS2[rune2Int('b', 0)] = s3.hash()
+
+	tranS3 := [256]string{}
+	tranS3[rune2Int('a', 0)] = s1.hash()
+	tranS3[rune2Int('b', 0)] = s0.hash()
+
+	expectedTranTab := map[string][256]string{
+		s0.hash(): tranS0,
+		s1.hash(): tranS1,
+		s2.hash(): tranS2,
+		s3.hash(): tranS3,
+	}
+	if len(dfa.TransitionTable) != len(expectedTranTab) {
+		t.Errorf("transition table is mismatched: want: %v entries, got: %v entries", len(expectedTranTab), len(dfa.TransitionTable))
+	}
+	for h, eTranTab := range expectedTranTab {
+		tranTab, ok := dfa.TransitionTable[h]
+		if !ok {
+			t.Errorf("no entry; hash: %v", h)
+			continue
+		}
+		if len(tranTab) != len(eTranTab) {
+			t.Errorf("transition table is mismatched: hash: %v, want: %v entries, got: %v entries", h, len(eTranTab), len(tranTab))
+		}
+		for c, eNext := range eTranTab {
+			if eNext == "" {
+				continue
+			}
+
+			next := tranTab[c]
+			if next == "" {
+				t.Errorf("no enatry: hash: %v, char: %v", h, c)
+			}
+			if next != eNext {
+				t.Errorf("next state is mismatched: want: %v, got: %v", eNext, next)
+			}
+		}
+	}
+
+	if dfa.InitialState != s0.hash() {
+		t.Errorf("initial state is mismatched: want: %v, got: %v", s0.hash(), dfa.InitialState)
+	}
+
+	accTab := map[string]spec.LexModeKindID{
+		s3.hash(): 1,
+	}
+	if len(dfa.AcceptingStatesTable) != len(accTab) {
+		t.Errorf("accepting states are mismatched: want: %v entries, got: %v entries", len(accTab), len(dfa.AcceptingStatesTable))
+	}
+	for eState, eID := range accTab {
+		id, ok := dfa.AcceptingStatesTable[eState]
+		if !ok {
+			t.Errorf("accepting state is not found: state: %v", eState)
+		}
+		if id != eID {
+			t.Errorf("ID is mismatched: state: %v, want: %v, got: %v", eState, eID, id)
+		}
+	}
+}
+
+func TestNewSymbolPosition(t *testing.T) {
+	tests := []struct {
+		n       uint16
+		endMark bool
+		err     bool
+	}{
+		{
+			n:       0,
+			endMark: false,
+			err:     true,
+		},
+		{
+			n:       0,
+			endMark: true,
+			err:     true,
+		},
+		{
+			n:       symbolPositionMin - 1,
+			endMark: false,
+			err:     true,
+		},
+		{
+			n:       symbolPositionMin - 1,
+			endMark: true,
+			err:     true,
+		},
+		{
+			n:       symbolPositionMin,
+			endMark: false,
+		},
+		{
+			n:       symbolPositionMin,
+			endMark: true,
+		},
+		{
+			n:       symbolPositionMax,
+			endMark: false,
+		},
+		{
+			n:       symbolPositionMax,
+			endMark: true,
+		},
+		{
+			n:       symbolPositionMax + 1,
+			endMark: false,
+			err:     true,
+		},
+		{
+			n:       symbolPositionMax + 1,
+			endMark: true,
+			err:     true,
+		},
+	}
+	for i, tt := range tests {
+		t.Run(fmt.Sprintf("#%v n: %v, endMark: %v", i, tt.n, tt.endMark), func(t *testing.T) {
+			pos, err := newSymbolPosition(tt.n, tt.endMark)
+			if tt.err {
+				if err == nil {
+					t.Fatal("err is nil")
+				}
+				return
+			}
+			if err != nil {
+				t.Fatal(err)
+			}
+			n, endMark := pos.describe()
+			if n != tt.n || endMark != tt.endMark {
+				t.Errorf("unexpected symbol position: want: n: %v, endMark: %v, got: n: %v, endMark: %v", tt.n, tt.endMark, n, endMark)
+			}
+		})
+	}
+}
+
+func TestByteTree(t *testing.T) {
+	tests := []struct {
+		root     byteTree
+		nullable bool
+		first    *symbolPositionSet
+		last     *symbolPositionSet
+	}{
+		{
+			root:     newSymbolNodeWithPos(0, 1),
+			nullable: false,
+			first:    newSymbolPositionSet().add(1),
+			last:     newSymbolPositionSet().add(1),
+		},
+		{
+			root:     newEndMarkerNodeWithPos(1, 1),
+			nullable: false,
+			first:    newSymbolPositionSet().add(1),
+			last:     newSymbolPositionSet().add(1),
+		},
+		{
+			root: newConcatNode(
+				newSymbolNodeWithPos(0, 1),
+				newSymbolNodeWithPos(0, 2),
+			),
+			nullable: false,
+			first:    newSymbolPositionSet().add(1),
+			last:     newSymbolPositionSet().add(2),
+		},
+		{
+			root: newConcatNode(
+				newRepeatNode(newSymbolNodeWithPos(0, 1)),
+				newSymbolNodeWithPos(0, 2),
+			),
+			nullable: false,
+			first:    newSymbolPositionSet().add(1).add(2),
+			last:     newSymbolPositionSet().add(2),
+		},
+		{
+			root: newConcatNode(
+				newSymbolNodeWithPos(0, 1),
+				newRepeatNode(newSymbolNodeWithPos(0, 2)),
+			),
+			nullable: false,
+			first:    newSymbolPositionSet().add(1),
+			last:     newSymbolPositionSet().add(1).add(2),
+		},
+		{
+			root: newConcatNode(
+				newRepeatNode(newSymbolNodeWithPos(0, 1)),
+				newRepeatNode(newSymbolNodeWithPos(0, 2)),
+			),
+			nullable: true,
+			first:    newSymbolPositionSet().add(1).add(2),
+			last:     newSymbolPositionSet().add(1).add(2),
+		},
+		{
+			root: newAltNode(
+				newSymbolNodeWithPos(0, 1),
+				newSymbolNodeWithPos(0, 2),
+			),
+			nullable: false,
+			first:    newSymbolPositionSet().add(1).add(2),
+			last:     newSymbolPositionSet().add(1).add(2),
+		},
+		{
+			root: newAltNode(
+				newRepeatNode(newSymbolNodeWithPos(0, 1)),
+				newSymbolNodeWithPos(0, 2),
+			),
+			nullable: true,
+			first:    newSymbolPositionSet().add(1).add(2),
+			last:     newSymbolPositionSet().add(1).add(2),
+		},
+		{
+			root: newAltNode(
+				newSymbolNodeWithPos(0, 1),
+				newRepeatNode(newSymbolNodeWithPos(0, 2)),
+			),
+			nullable: true,
+			first:    newSymbolPositionSet().add(1).add(2),
+			last:     newSymbolPositionSet().add(1).add(2),
+		},
+		{
+			root: newAltNode(
+				newRepeatNode(newSymbolNodeWithPos(0, 1)),
+				newRepeatNode(newSymbolNodeWithPos(0, 2)),
+			),
+			nullable: true,
+			first:    newSymbolPositionSet().add(1).add(2),
+			last:     newSymbolPositionSet().add(1).add(2),
+		},
+		{
+			root:     newRepeatNode(newSymbolNodeWithPos(0, 1)),
+			nullable: true,
+			first:    newSymbolPositionSet().add(1),
+			last:     newSymbolPositionSet().add(1),
+		},
+		{
+			root:     newOptionNode(newSymbolNodeWithPos(0, 1)),
+			nullable: true,
+			first:    newSymbolPositionSet().add(1),
+			last:     newSymbolPositionSet().add(1),
+		},
+	}
+	for i, tt := range tests {
+		t.Run(fmt.Sprintf("#%v", i), func(t *testing.T) {
+			if tt.root.nullable() != tt.nullable {
+				t.Errorf("unexpected nullable attribute; want: %v, got: %v", tt.nullable, tt.root.nullable())
+			}
+			if tt.first.hash() != tt.root.first().hash() {
+				t.Errorf("unexpected first positions attribute; want: %v, got: %v", tt.first, tt.root.first())
+			}
+			if tt.last.hash() != tt.root.last().hash() {
+				t.Errorf("unexpected last positions attribute; want: %v, got: %v", tt.last, tt.root.last())
+			}
+		})
+	}
+}
+
+func newSymbolNodeWithPos(v byte, pos symbolPosition) *symbolNode {
+	n := newSymbolNode(v)
+	n.pos = pos
+	return n
+}
+
+func newEndMarkerNodeWithPos(id int, pos symbolPosition) *endMarkerNode {
+	n := newEndMarkerNode(spec.LexModeKindID(id))
+	n.pos = pos
+	return n
+}
+
+func TestFollowAndSymbolTable(t *testing.T) {
+	symPos := func(n uint16) symbolPosition {
+		pos, err := newSymbolPosition(n, false)
+		if err != nil {
+			panic(err)
+		}
+		return pos
+	}
+
+	endPos := func(n uint16) symbolPosition {
+		pos, err := newSymbolPosition(n, true)
+		if err != nil {
+			panic(err)
+		}
+		return pos
+	}
+
+	p := parser.NewParser(spec.LexKindName("test"), strings.NewReader("(a|b)*abb"))
+	cpt, err := p.Parse()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	bt, symTab, err := ConvertCPTreeToByteTree(map[spec.LexModeKindID]parser.CPTree{
+		spec.LexModeKindIDMin: cpt,
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	{
+		followTab := genFollowTable(bt)
+		if followTab == nil {
+			t.Fatal("follow table is nil")
+		}
+		expectedFollowTab := followTable{
+			1: newSymbolPositionSet().add(symPos(1)).add(symPos(2)).add(symPos(3)),
+			2: newSymbolPositionSet().add(symPos(1)).add(symPos(2)).add(symPos(3)),
+			3: newSymbolPositionSet().add(symPos(4)),
+			4: newSymbolPositionSet().add(symPos(5)),
+			5: newSymbolPositionSet().add(endPos(6)),
+		}
+		testFollowTable(t, expectedFollowTab, followTab)
+	}
+
+	{
+		entry := func(v byte) byteRange {
+			return byteRange{
+				from: v,
+				to:   v,
+			}
+		}
+
+		expectedSymTab := &symbolTable{
+			symPos2Byte: map[symbolPosition]byteRange{
+				symPos(1): entry(byte('a')),
+				symPos(2): entry(byte('b')),
+				symPos(3): entry(byte('a')),
+				symPos(4): entry(byte('b')),
+				symPos(5): entry(byte('b')),
+			},
+			endPos2ID: map[symbolPosition]spec.LexModeKindID{
+				endPos(6): 1,
+			},
+		}
+		testSymbolTable(t, expectedSymTab, symTab)
+	}
+}
+
+func testFollowTable(t *testing.T, expected, actual followTable) {
+	if len(actual) != len(expected) {
+		t.Errorf("unexpected number of the follow table entries; want: %v, got: %v", len(expected), len(actual))
+	}
+	for ePos, eSet := range expected {
+		aSet, ok := actual[ePos]
+		if !ok {
+			t.Fatalf("follow entry is not found: position: %v, follow: %v", ePos, eSet)
+		}
+		if aSet.hash() != eSet.hash() {
+			t.Fatalf("follow entry of position %v is mismatched: want: %v, got: %v", ePos, aSet, eSet)
+		}
+	}
+}
+
+func testSymbolTable(t *testing.T, expected, actual *symbolTable) {
+	t.Helper()
+
+	if len(actual.symPos2Byte) != len(expected.symPos2Byte) {
+		t.Errorf("unexpected symPos2Byte entries: want: %v entries, got: %v entries", len(expected.symPos2Byte), len(actual.symPos2Byte))
+	}
+	for ePos, eByte := range expected.symPos2Byte {
+		byte, ok := actual.symPos2Byte[ePos]
+		if !ok {
+			t.Errorf("a symbol position entry is not found: %v -> %v", ePos, eByte)
+			continue
+		}
+		if byte.from != eByte.from || byte.to != eByte.to {
+			t.Errorf("unexpected symbol position entry: want: %v -> %v, got: %v -> %v", ePos, eByte, ePos, byte)
+		}
+	}
+
+	if len(actual.endPos2ID) != len(expected.endPos2ID) {
+		t.Errorf("unexpected endPos2ID entries: want: %v entries, got: %v entries", len(expected.endPos2ID), len(actual.endPos2ID))
+	}
+	for ePos, eID := range expected.endPos2ID {
+		id, ok := actual.endPos2ID[ePos]
+		if !ok {
+			t.Errorf("an end position entry is not found: %v -> %v", ePos, eID)
+			continue
+		}
+		if id != eID {
+			t.Errorf("unexpected end position entry: want: %v -> %v, got: %v -> %v", ePos, eID, ePos, id)
+		}
+	}
+}
diff --git a/tests/unit/urubu/grammar/lexical/parser.go b/tests/unit/urubu/grammar/lexical/parser.go
new file mode 100644
index 0000000..d5d7039
--- /dev/null
+++ b/tests/unit/urubu/grammar/lexical/parser.go
@@ -0,0 +1,1907 @@
+package parser
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+	"testing"
+
+	spec "urubu/spec/grammar"
+	"urubu/ucd"
+)
+
+func TestLexer(t *testing.T) {
+	tests := []struct {
+		caption string
+		src     string
+		tokens  []*token
+		err     error
+	}{
+		{
+			caption: "lexer can recognize ordinaly characters",
+			src:     "123abcいろは",
+			tokens: []*token{
+				newToken(tokenKindChar, '1'),
+				newToken(tokenKindChar, '2'),
+				newToken(tokenKindChar, '3'),
+				newToken(tokenKindChar, 'a'),
+				newToken(tokenKindChar, 'b'),
+				newToken(tokenKindChar, 'c'),
+				newToken(tokenKindChar, 'い'),
+				newToken(tokenKindChar, 'ろ'),
+				newToken(tokenKindChar, 'は'),
+				newToken(tokenKindEOF, nullChar),
+			},
+		},
+		{
+			caption: "lexer can recognize the special characters in default mode",
+			src:     ".*+?|()[\\u",
+			tokens: []*token{
+				newToken(tokenKindAnyChar, nullChar),
+				newToken(tokenKindRepeat, nullChar),
+				newToken(tokenKindRepeatOneOrMore, nullChar),
+				newToken(tokenKindOption, nullChar),
+				newToken(tokenKindAlt, nullChar),
+				newToken(tokenKindGroupOpen, nullChar),
+				newToken(tokenKindGroupClose, nullChar),
+				newToken(tokenKindBExpOpen, nullChar),
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindEOF, nullChar),
+			},
+		},
+		{
+			caption: "lexer can recognize the escape sequences in default mode",
+			src:     "\\\\\\.\\*\\+\\?\\|\\(\\)\\[",
+			tokens: []*token{
+				newToken(tokenKindChar, '\\'),
+				newToken(tokenKindChar, '.'),
+				newToken(tokenKindChar, '*'),
+				newToken(tokenKindChar, '+'),
+				newToken(tokenKindChar, '?'),
+				newToken(tokenKindChar, '|'),
+				newToken(tokenKindChar, '('),
+				newToken(tokenKindChar, ')'),
+				newToken(tokenKindChar, '['),
+				newToken(tokenKindEOF, nullChar),
+			},
+		},
+		{
+			caption: "], {, and } are treated as an ordinary character in default mode",
+			src:     "]{}",
+			tokens: []*token{
+				newToken(tokenKindChar, ']'),
+				newToken(tokenKindChar, '{'),
+				newToken(tokenKindChar, '}'),
+				newToken(tokenKindEOF, nullChar),
+			},
+		},
+		{
+			caption: "lexer can recognize the special characters in bracket expression mode",
+			src:     "[a-z\\u{09AF}][^a-z\\u{09abcf}]",
+			tokens: []*token{
+				newToken(tokenKindBExpOpen, nullChar),
+				newToken(tokenKindChar, 'a'),
+				newToken(tokenKindCharRange, nullChar),
+				newToken(tokenKindChar, 'z'),
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCodePointToken("09AF"),
+				newToken(tokenKindRBrace, nullChar),
+				newToken(tokenKindBExpClose, nullChar),
+				newToken(tokenKindInverseBExpOpen, nullChar),
+				newToken(tokenKindChar, 'a'),
+				newToken(tokenKindCharRange, nullChar),
+				newToken(tokenKindChar, 'z'),
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCodePointToken("09abcf"),
+				newToken(tokenKindRBrace, nullChar),
+				newToken(tokenKindBExpClose, nullChar),
+				newToken(tokenKindEOF, nullChar),
+			},
+		},
+		{
+			caption: "lexer can recognize the escape sequences in bracket expression mode",
+			src:     "[\\^a\\-z]",
+			tokens: []*token{
+				newToken(tokenKindBExpOpen, nullChar),
+				newToken(tokenKindChar, '^'),
+				newToken(tokenKindChar, 'a'),
+				newToken(tokenKindChar, '-'),
+				newToken(tokenKindChar, 'z'),
+				newToken(tokenKindBExpClose, nullChar),
+				newToken(tokenKindEOF, nullChar),
+			},
+		},
+		{
+			caption: "in a bracket expression, the special characters are also handled as normal characters",
+			src:     "[\\\\.*+?|()[",
+			tokens: []*token{
+				newToken(tokenKindBExpOpen, nullChar),
+				newToken(tokenKindChar, '\\'),
+				newToken(tokenKindChar, '.'),
+				newToken(tokenKindChar, '*'),
+				newToken(tokenKindChar, '+'),
+				newToken(tokenKindChar, '?'),
+				newToken(tokenKindChar, '|'),
+				newToken(tokenKindChar, '('),
+				newToken(tokenKindChar, ')'),
+				newToken(tokenKindChar, '['),
+				newToken(tokenKindEOF, nullChar),
+			},
+		},
+		{
+			caption: "hyphen symbols that appear in bracket expressions are handled as the character range symbol or ordinary characters",
+			// [...-...][...-][-...][-]
+			//  ~~~~~~~     ~  ~     ~
+			//     ^        ^  ^     ^
+			//     |        |  |     `-- Ordinary Character (b)
+			//     |        |  `-- Ordinary Character (b)
+			//     |        `-- Ordinary Character (b)
+			//     `-- Character Range (a)
+			//
+			// a. *-* is handled as a character-range expression.
+			// b. *-, -*, or - are handled as ordinary characters.
+			src: "[a-z][a-][-z][-][--][---][^a-z][^a-][^-z][^-][^--][^---]",
+			tokens: []*token{
+				newToken(tokenKindBExpOpen, nullChar),
+				newToken(tokenKindChar, 'a'),
+				newToken(tokenKindCharRange, nullChar),
+				newToken(tokenKindChar, 'z'),
+				newToken(tokenKindBExpClose, nullChar),
+				newToken(tokenKindBExpOpen, nullChar),
+				newToken(tokenKindChar, 'a'),
+				newToken(tokenKindChar, '-'),
+				newToken(tokenKindBExpClose, nullChar),
+				newToken(tokenKindBExpOpen, nullChar),
+				newToken(tokenKindChar, '-'),
+				newToken(tokenKindChar, 'z'),
+				newToken(tokenKindBExpClose, nullChar),
+				newToken(tokenKindBExpOpen, nullChar),
+				newToken(tokenKindChar, '-'),
+				newToken(tokenKindBExpClose, nullChar),
+				newToken(tokenKindBExpOpen, nullChar),
+				newToken(tokenKindChar, '-'),
+				newToken(tokenKindChar, '-'),
+				newToken(tokenKindBExpClose, nullChar),
+				newToken(tokenKindBExpOpen, nullChar),
+				newToken(tokenKindChar, '-'),
+				newToken(tokenKindCharRange, nullChar),
+				newToken(tokenKindChar, '-'),
+				newToken(tokenKindBExpClose, nullChar),
+
+				newToken(tokenKindInverseBExpOpen, nullChar),
+				newToken(tokenKindChar, 'a'),
+				newToken(tokenKindCharRange, nullChar),
+				newToken(tokenKindChar, 'z'),
+				newToken(tokenKindBExpClose, nullChar),
+				newToken(tokenKindInverseBExpOpen, nullChar),
+				newToken(tokenKindChar, 'a'),
+				newToken(tokenKindChar, '-'),
+				newToken(tokenKindBExpClose, nullChar),
+				newToken(tokenKindInverseBExpOpen, nullChar),
+				newToken(tokenKindChar, '-'),
+				newToken(tokenKindChar, 'z'),
+				newToken(tokenKindBExpClose, nullChar),
+				newToken(tokenKindInverseBExpOpen, nullChar),
+				newToken(tokenKindChar, '-'),
+				newToken(tokenKindBExpClose, nullChar),
+				newToken(tokenKindInverseBExpOpen, nullChar),
+				newToken(tokenKindChar, '-'),
+				newToken(tokenKindChar, '-'),
+				newToken(tokenKindBExpClose, nullChar),
+				newToken(tokenKindInverseBExpOpen, nullChar),
+				newToken(tokenKindChar, '-'),
+				newToken(tokenKindCharRange, nullChar),
+				newToken(tokenKindChar, '-'),
+				newToken(tokenKindBExpClose, nullChar),
+
+				newToken(tokenKindEOF, nullChar),
+			},
+		},
+		{
+			caption: "caret symbols that appear in bracket expressions are handled as the logical inverse symbol or ordinary characters",
+			// [^...^...][^]
+			// ~~   ~    ~~
+			// ^    ^    ^^
+			// |    |    |`-- Ordinary Character (c)
+			// |    |    `-- Bracket Expression
+			// |    `-- Ordinary Character (b)
+			// `-- Inverse Bracket Expression (a)
+			//
+			// a. Bracket expressions that have a caret symbol at the beginning are handled as logical inverse expressions.
+			// b. caret symbols that appear as the second and the subsequent symbols are handled as ordinary symbols.
+			// c. When a bracket expression has just one symbol, a caret symbol at the beginning is handled as an ordinary character.
+			src: "[^^][^]",
+			tokens: []*token{
+				newToken(tokenKindInverseBExpOpen, nullChar),
+				newToken(tokenKindChar, '^'),
+				newToken(tokenKindBExpClose, nullChar),
+				newToken(tokenKindBExpOpen, nullChar),
+				newToken(tokenKindChar, '^'),
+				newToken(tokenKindBExpClose, nullChar),
+				newToken(tokenKindEOF, nullChar),
+			},
+		},
+		{
+			caption: "lexer raises an error when an invalid escape sequence appears",
+			src:     "\\@",
+			err:     synErrInvalidEscSeq,
+		},
+		{
+			caption: "lexer raises an error when the incomplete escape sequence (EOF following \\) appears",
+			src:     "\\",
+			err:     synErrIncompletedEscSeq,
+		},
+		{
+			caption: "lexer raises an error when an invalid escape sequence appears",
+			src:     "[\\@",
+			tokens: []*token{
+				newToken(tokenKindBExpOpen, nullChar),
+			},
+			err: synErrInvalidEscSeq,
+		},
+		{
+			caption: "lexer raises an error when the incomplete escape sequence (EOF following \\) appears",
+			src:     "[\\",
+			tokens: []*token{
+				newToken(tokenKindBExpOpen, nullChar),
+			},
+			err: synErrIncompletedEscSeq,
+		},
+		{
+			caption: "lexer can recognize the special characters and code points in code point expression mode",
+			src:     "\\u{0123}\\u{4567}\\u{89abcd}\\u{efAB}\\u{CDEF01}[\\u{0123}\\u{4567}\\u{89abcd}\\u{efAB}\\u{CDEF01}][^\\u{0123}\\u{4567}\\u{89abcd}\\u{efAB}\\u{CDEF01}]",
+			tokens: []*token{
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCodePointToken("0123"),
+				newToken(tokenKindRBrace, nullChar),
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCodePointToken("4567"),
+				newToken(tokenKindRBrace, nullChar),
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCodePointToken("89abcd"),
+				newToken(tokenKindRBrace, nullChar),
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCodePointToken("efAB"),
+				newToken(tokenKindRBrace, nullChar),
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCodePointToken("CDEF01"),
+				newToken(tokenKindRBrace, nullChar),
+
+				newToken(tokenKindBExpOpen, nullChar),
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCodePointToken("0123"),
+				newToken(tokenKindRBrace, nullChar),
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCodePointToken("4567"),
+				newToken(tokenKindRBrace, nullChar),
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCodePointToken("89abcd"),
+				newToken(tokenKindRBrace, nullChar),
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCodePointToken("efAB"),
+				newToken(tokenKindRBrace, nullChar),
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCodePointToken("CDEF01"),
+				newToken(tokenKindRBrace, nullChar),
+				newToken(tokenKindBExpClose, nullChar),
+
+				newToken(tokenKindInverseBExpOpen, nullChar),
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCodePointToken("0123"),
+				newToken(tokenKindRBrace, nullChar),
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCodePointToken("4567"),
+				newToken(tokenKindRBrace, nullChar),
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCodePointToken("89abcd"),
+				newToken(tokenKindRBrace, nullChar),
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCodePointToken("efAB"),
+				newToken(tokenKindRBrace, nullChar),
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCodePointToken("CDEF01"),
+				newToken(tokenKindRBrace, nullChar),
+				newToken(tokenKindBExpClose, nullChar),
+
+				newToken(tokenKindEOF, nullChar),
+			},
+		},
+		{
+			caption: "a one digit hex string isn't a valid code point",
+			src:     "\\u{0",
+			tokens: []*token{
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+			},
+			err: synErrInvalidCodePoint,
+		},
+		{
+			caption: "a two digits hex string isn't a valid code point",
+			src:     "\\u{01",
+			tokens: []*token{
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+			},
+			err: synErrInvalidCodePoint,
+		},
+		{
+			caption: "a three digits hex string isn't a valid code point",
+			src:     "\\u{012",
+			tokens: []*token{
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+			},
+			err: synErrInvalidCodePoint,
+		},
+		{
+			caption: "a four digits hex string is a valid code point",
+			src:     "\\u{0123}",
+			tokens: []*token{
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCodePointToken("0123"),
+				newToken(tokenKindRBrace, nullChar),
+			},
+		},
+		{
+			caption: "a five digits hex string isn't a valid code point",
+			src:     "\\u{01234",
+			tokens: []*token{
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+			},
+			err: synErrInvalidCodePoint,
+		},
+		{
+			caption: "a six digits hex string is a valid code point",
+			src:     "\\u{012345}",
+			tokens: []*token{
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCodePointToken("012345"),
+				newToken(tokenKindRBrace, nullChar),
+			},
+		},
+		{
+			caption: "a seven digits hex string isn't a valid code point",
+			src:     "\\u{0123456",
+			tokens: []*token{
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+			},
+			err: synErrInvalidCodePoint,
+		},
+		{
+			caption: "a code point must be hex digits",
+			src:     "\\u{g",
+			tokens: []*token{
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+			},
+			err: synErrInvalidCodePoint,
+		},
+		{
+			caption: "a code point must be hex digits",
+			src:     "\\u{G",
+			tokens: []*token{
+				newToken(tokenKindCodePointLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+			},
+			err: synErrInvalidCodePoint,
+		},
+		{
+			caption: "lexer can recognize the special characters and symbols in character property expression mode",
+			src:     "\\p{Letter}\\p{General_Category=Letter}[\\p{Letter}\\p{General_Category=Letter}][^\\p{Letter}\\p{General_Category=Letter}]",
+			tokens: []*token{
+				newToken(tokenKindCharPropLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCharPropSymbolToken("Letter"),
+				newToken(tokenKindRBrace, nullChar),
+				newToken(tokenKindCharPropLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCharPropSymbolToken("General_Category"),
+				newToken(tokenKindEqual, nullChar),
+				newCharPropSymbolToken("Letter"),
+				newToken(tokenKindRBrace, nullChar),
+
+				newToken(tokenKindBExpOpen, nullChar),
+				newToken(tokenKindCharPropLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCharPropSymbolToken("Letter"),
+				newToken(tokenKindRBrace, nullChar),
+				newToken(tokenKindCharPropLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCharPropSymbolToken("General_Category"),
+				newToken(tokenKindEqual, nullChar),
+				newCharPropSymbolToken("Letter"),
+				newToken(tokenKindRBrace, nullChar),
+				newToken(tokenKindBExpClose, nullChar),
+
+				newToken(tokenKindInverseBExpOpen, nullChar),
+				newToken(tokenKindCharPropLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCharPropSymbolToken("Letter"),
+				newToken(tokenKindRBrace, nullChar),
+				newToken(tokenKindCharPropLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newCharPropSymbolToken("General_Category"),
+				newToken(tokenKindEqual, nullChar),
+				newCharPropSymbolToken("Letter"),
+				newToken(tokenKindRBrace, nullChar),
+				newToken(tokenKindBExpClose, nullChar),
+
+				newToken(tokenKindEOF, nullChar),
+			},
+		},
+		{
+			caption: "lexer can recognize the special characters and symbols in fragment expression mode",
+			src:     "\\f{integer}",
+			tokens: []*token{
+				newToken(tokenKindFragmentLeader, nullChar),
+				newToken(tokenKindLBrace, nullChar),
+				newFragmentSymbolToken("integer"),
+				newToken(tokenKindRBrace, nullChar),
+
+				newToken(tokenKindEOF, nullChar),
+			},
+		},
+		{
+			caption: "a fragment expression is not supported in a bracket expression",
+			src:     "[\\f",
+			tokens: []*token{
+				newToken(tokenKindBExpOpen, nullChar),
+			},
+			err: synErrInvalidEscSeq,
+		},
+		{
+			caption: "a fragment expression is not supported in an inverse bracket expression",
+			src:     "[^\\f",
+			tokens: []*token{
+				newToken(tokenKindInverseBExpOpen, nullChar),
+			},
+			err: synErrInvalidEscSeq,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.caption, func(t *testing.T) {
+			lex := newLexer(strings.NewReader(tt.src))
+			var err error
+			var tok *token
+			i := 0
+			for {
+				tok, err = lex.next()
+				if err != nil {
+					break
+				}
+				if i >= len(tt.tokens) {
+					break
+				}
+				eTok := tt.tokens[i]
+				i++
+				testToken(t, tok, eTok)
+
+				if tok.kind == tokenKindEOF {
+					break
+				}
+			}
+			if tt.err != nil {
+				if err != ParseErr {
+					t.Fatalf("unexpected error: want: %v, got: %v", ParseErr, err)
+				}
+				detail, cause := lex.error()
+				if cause != tt.err {
+					t.Fatalf("unexpected error: want: %v, got: %v (%v)", tt.err, cause, detail)
+				}
+			} else {
+				if err != nil {
+					t.Fatalf("unexpected error: %v", err)
+				}
+			}
+			if i < len(tt.tokens) {
+				t.Fatalf("expecte more tokens")
+			}
+		})
+	}
+}
+
+func testToken(t *testing.T, a, e *token) {
+	t.Helper()
+	if e.kind != a.kind || e.char != a.char || e.codePoint != a.codePoint {
+		t.Fatalf("unexpected token: want: %+v, got: %+v", e, a)
+	}
+}
+
+func TestParse(t *testing.T) {
+	tests := []struct {
+		pattern     string
+		fragments   map[spec.LexKindName]string
+		ast         CPTree
+		syntaxError error
+
+		// When an AST is large, as patterns containing a character property expression, this test only checks
+		// that the pattern is parsable. The check of the validity of such AST is performed by checking that it
+		// can be matched correctly using the driver.
+		skipTestAST bool
+	}{
+		{
+			pattern: "a",
+			ast:     newSymbolNode('a'),
+		},
+		{
+			pattern: "abc",
+			ast: genConcatNode(
+				newSymbolNode('a'),
+				newSymbolNode('b'),
+				newSymbolNode('c'),
+			),
+		},
+		{
+			pattern: "a?",
+			ast: newOptionNode(
+				newSymbolNode('a'),
+			),
+		},
+		{
+			pattern: "[abc]?",
+			ast: newOptionNode(
+				genAltNode(
+					newSymbolNode('a'),
+					newSymbolNode('b'),
+					newSymbolNode('c'),
+				),
+			),
+		},
+		{
+			pattern: "\\u{3042}?",
+			ast: newOptionNode(
+				newSymbolNode('\u3042'),
+			),
+		},
+		{
+			pattern:     "\\p{Letter}?",
+			skipTestAST: true,
+		},
+		{
+			pattern: "\\f{a2c}?",
+			fragments: map[spec.LexKindName]string{
+				"a2c": "abc",
+			},
+			ast: newOptionNode(
+				newFragmentNode("a2c",
+					genConcatNode(
+						newSymbolNode('a'),
+						newSymbolNode('b'),
+						newSymbolNode('c'),
+					),
+				),
+			),
+		},
+		{
+			pattern: "(a)?",
+			ast: newOptionNode(
+				newSymbolNode('a'),
+			),
+		},
+		{
+			pattern: "((a?)?)?",
+			ast: newOptionNode(
+				newOptionNode(
+					newOptionNode(
+						newSymbolNode('a'),
+					),
+				),
+			),
+		},
+		{
+			pattern: "(abc)?",
+			ast: newOptionNode(
+				genConcatNode(
+					newSymbolNode('a'),
+					newSymbolNode('b'),
+					newSymbolNode('c'),
+				),
+			),
+		},
+		{
+			pattern: "(a|b)?",
+			ast: newOptionNode(
+				genAltNode(
+					newSymbolNode('a'),
+					newSymbolNode('b'),
+				),
+			),
+		},
+		{
+			pattern:     "?",
+			syntaxError: synErrRepNoTarget,
+		},
+		{
+			pattern:     "(?)",
+			syntaxError: synErrRepNoTarget,
+		},
+		{
+			pattern:     "a|?",
+			syntaxError: synErrRepNoTarget,
+		},
+		{
+			pattern:     "?|b",
+			syntaxError: synErrRepNoTarget,
+		},
+		{
+			pattern:     "a??",
+			syntaxError: synErrRepNoTarget,
+		},
+		{
+			pattern: "a*",
+			ast: newRepeatNode(
+				newSymbolNode('a'),
+			),
+		},
+		{
+			pattern: "[abc]*",
+			ast: newRepeatNode(
+				genAltNode(
+					newSymbolNode('a'),
+					newSymbolNode('b'),
+					newSymbolNode('c'),
+				),
+			),
+		},
+		{
+			pattern: "\\u{3042}*",
+			ast: newRepeatNode(
+				newSymbolNode('\u3042'),
+			),
+		},
+		{
+			pattern:     "\\p{Letter}*",
+			skipTestAST: true,
+		},
+		{
+			pattern: "\\f{a2c}*",
+			fragments: map[spec.LexKindName]string{
+				"a2c": "abc",
+			},
+			ast: newRepeatNode(
+				newFragmentNode("a2c",
+					genConcatNode(
+						newSymbolNode('a'),
+						newSymbolNode('b'),
+						newSymbolNode('c'),
+					),
+				),
+			),
+		},
+		{
+			pattern: "((a*)*)*",
+			ast: newRepeatNode(
+				newRepeatNode(
+					newRepeatNode(
+						newSymbolNode('a'),
+					),
+				),
+			),
+		},
+		{
+			pattern: "(abc)*",
+			ast: newRepeatNode(
+				genConcatNode(
+					newSymbolNode('a'),
+					newSymbolNode('b'),
+					newSymbolNode('c'),
+				),
+			),
+		},
+		{
+			pattern: "(a|b)*",
+			ast: newRepeatNode(
+				genAltNode(
+					newSymbolNode('a'),
+					newSymbolNode('b'),
+				),
+			),
+		},
+		{
+			pattern:     "*",
+			syntaxError: synErrRepNoTarget,
+		},
+		{
+			pattern:     "(*)",
+			syntaxError: synErrRepNoTarget,
+		},
+		{
+			pattern:     "a|*",
+			syntaxError: synErrRepNoTarget,
+		},
+		{
+			pattern:     "*|b",
+			syntaxError: synErrRepNoTarget,
+		},
+		{
+			pattern:     "a**",
+			syntaxError: synErrRepNoTarget,
+		},
+		{
+			pattern: "a+",
+			ast: genConcatNode(
+				newSymbolNode('a'),
+				newRepeatNode(
+					newSymbolNode('a'),
+				),
+			),
+		},
+		{
+			pattern: "[abc]+",
+			ast: genConcatNode(
+				genAltNode(
+					newSymbolNode('a'),
+					newSymbolNode('b'),
+					newSymbolNode('c'),
+				),
+				newRepeatNode(
+					genAltNode(
+						newSymbolNode('a'),
+						newSymbolNode('b'),
+						newSymbolNode('c'),
+					),
+				),
+			),
+		},
+		{
+			pattern: "\\u{3042}+",
+			ast: genConcatNode(
+				newSymbolNode('\u3042'),
+				newRepeatNode(
+					newSymbolNode('\u3042'),
+				),
+			),
+		},
+		{
+			pattern:     "\\p{Letter}+",
+			skipTestAST: true,
+		},
+		{
+			pattern: "\\f{a2c}+",
+			fragments: map[spec.LexKindName]string{
+				"a2c": "abc",
+			},
+			ast: genConcatNode(
+				newFragmentNode("a2c",
+					genConcatNode(
+						newSymbolNode('a'),
+						newSymbolNode('b'),
+						newSymbolNode('c'),
+					),
+				),
+				newRepeatNode(
+					newFragmentNode("a2c",
+						genConcatNode(
+							newSymbolNode('a'),
+							newSymbolNode('b'),
+							newSymbolNode('c'),
+						),
+					),
+				),
+			),
+		},
+		{
+			pattern: "((a+)+)+",
+			ast: genConcatNode(
+				genConcatNode(
+					genConcatNode(
+						genConcatNode(
+							newSymbolNode('a'),
+							newRepeatNode(
+								newSymbolNode('a'),
+							),
+						),
+						newRepeatNode(
+							genConcatNode(
+								newSymbolNode('a'),
+								newRepeatNode(
+									newSymbolNode('a'),
+								),
+							),
+						),
+					),
+					newRepeatNode(
+						genConcatNode(
+							genConcatNode(
+								newSymbolNode('a'),
+								newRepeatNode(
+									newSymbolNode('a'),
+								),
+							),
+							newRepeatNode(
+								genConcatNode(
+									newSymbolNode('a'),
+									newRepeatNode(
+										newSymbolNode('a'),
+									),
+								),
+							),
+						),
+					),
+				),
+			),
+		},
+		{
+			pattern: "(abc)+",
+			ast: genConcatNode(
+				genConcatNode(
+					newSymbolNode('a'),
+					newSymbolNode('b'),
+					newSymbolNode('c'),
+				),
+				newRepeatNode(
+					genConcatNode(
+						newSymbolNode('a'),
+						newSymbolNode('b'),
+						newSymbolNode('c'),
+					),
+				),
+			),
+		},
+		{
+			pattern: "(a|b)+",
+			ast: genConcatNode(
+				genAltNode(
+					newSymbolNode('a'),
+					newSymbolNode('b'),
+				),
+				newRepeatNode(
+					genAltNode(
+						newSymbolNode('a'),
+						newSymbolNode('b'),
+					),
+				),
+			),
+		},
+		{
+			pattern:     "+",
+			syntaxError: synErrRepNoTarget,
+		},
+		{
+			pattern:     "(+)",
+			syntaxError: synErrRepNoTarget,
+		},
+		{
+			pattern:     "a|+",
+			syntaxError: synErrRepNoTarget,
+		},
+		{
+			pattern:     "+|b",
+			syntaxError: synErrRepNoTarget,
+		},
+		{
+			pattern:     "a++",
+			syntaxError: synErrRepNoTarget,
+		},
+		{
+			pattern: ".",
+			ast:     newRangeSymbolNode(0x00, 0x10FFFF),
+		},
+		{
+			pattern: "[a]",
+			ast:     newSymbolNode('a'),
+		},
+		{
+			pattern: "[abc]",
+			ast: genAltNode(
+				newSymbolNode('a'),
+				newSymbolNode('b'),
+				newSymbolNode('c'),
+			),
+		},
+		{
+			pattern: "[a-z]",
+			ast:     newRangeSymbolNode('a', 'z'),
+		},
+		{
+			pattern: "[A-Za-z]",
+			ast: genAltNode(
+				newRangeSymbolNode('A', 'Z'),
+				newRangeSymbolNode('a', 'z'),
+			),
+		},
+		{
+			pattern: "[\\u{004E}]",
+			ast:     newSymbolNode('N'),
+		},
+		{
+			pattern: "[\\u{0061}-\\u{007A}]",
+			ast:     newRangeSymbolNode('a', 'z'),
+		},
+		{
+			pattern:     "[\\p{Lu}]",
+			skipTestAST: true,
+		},
+		{
+			pattern:     "[a-\\p{Lu}]",
+			syntaxError: synErrRangePropIsUnavailable,
+		},
+		{
+			pattern:     "[\\p{Lu}-z]",
+			syntaxError: synErrRangePropIsUnavailable,
+		},
+		{
+			pattern:     "[\\p{Lu}-\\p{Ll}]",
+			syntaxError: synErrRangePropIsUnavailable,
+		},
+		{
+			pattern:     "[z-a]",
+			syntaxError: synErrRangeInvalidOrder,
+		},
+		{
+			pattern:     "a[]",
+			syntaxError: synErrBExpNoElem,
+		},
+		{
+			pattern:     "[]a",
+			syntaxError: synErrBExpNoElem,
+		},
+		{
+			pattern:     "[]",
+			syntaxError: synErrBExpNoElem,
+		},
+		{
+			pattern: "[^\\u{004E}]",
+			ast: genAltNode(
+				newRangeSymbolNode(0x00, '\u004E'-1),
+				newRangeSymbolNode('\u004E'+1, 0x10FFFF),
+			),
+		},
+		{
+			pattern: "[^\\u{0061}-\\u{007A}]",
+			ast: genAltNode(
+				newRangeSymbolNode(0x00, '\u0061'-1),
+				newRangeSymbolNode('\u007A'+1, 0x10FFFF),
+			),
+		},
+		{
+			pattern:     "[^\\p{Lu}]",
+			skipTestAST: true,
+		},
+		{
+			pattern:     "[^a-\\p{Lu}]",
+			syntaxError: synErrRangePropIsUnavailable,
+		},
+		{
+			pattern:     "[^\\p{Lu}-z]",
+			syntaxError: synErrRangePropIsUnavailable,
+		},
+		{
+			pattern:     "[^\\p{Lu}-\\p{Ll}]",
+			syntaxError: synErrRangePropIsUnavailable,
+		},
+		{
+			pattern:     "[^\\u{0000}-\\u{10FFFF}]",
+			syntaxError: synErrUnmatchablePattern,
+		},
+		{
+			pattern:     "[^\\u{0000}-\\u{FFFF}\\u{010000}-\\u{10FFFF}]",
+			syntaxError: synErrUnmatchablePattern,
+		},
+		{
+			pattern: "[^]",
+			ast:     newSymbolNode('^'),
+		},
+		{
+			pattern:     "[",
+			syntaxError: synErrBExpUnclosed,
+		},
+		{
+			pattern:     "([",
+			syntaxError: synErrBExpUnclosed,
+		},
+		{
+			pattern:     "[a",
+			syntaxError: synErrBExpUnclosed,
+		},
+		{
+			pattern:     "([a",
+			syntaxError: synErrBExpUnclosed,
+		},
+		{
+			pattern:     "[a-",
+			syntaxError: synErrBExpUnclosed,
+		},
+		{
+			pattern:     "([a-",
+			syntaxError: synErrBExpUnclosed,
+		},
+		{
+			pattern:     "[^",
+			syntaxError: synErrBExpUnclosed,
+		},
+		{
+			pattern:     "([^",
+			syntaxError: synErrBExpUnclosed,
+		},
+		{
+			pattern:     "[^a",
+			syntaxError: synErrBExpUnclosed,
+		},
+		{
+			pattern:     "([^a",
+			syntaxError: synErrBExpUnclosed,
+		},
+		{
+			pattern:     "[^a-",
+			syntaxError: synErrBExpUnclosed,
+		},
+		{
+			pattern:     "([^a-",
+			syntaxError: synErrBExpUnclosed,
+		},
+		{
+			pattern: "]",
+			ast:     newSymbolNode(']'),
+		},
+		{
+			pattern:     "(]",
+			syntaxError: synErrGroupUnclosed,
+		},
+		{
+			pattern: "a]",
+			ast: genConcatNode(
+				newSymbolNode('a'),
+				newSymbolNode(']'),
+			),
+		},
+		{
+			pattern:     "(a]",
+			syntaxError: synErrGroupUnclosed,
+		},
+		{
+			pattern:     "([)",
+			syntaxError: synErrBExpUnclosed,
+		},
+		{
+			pattern:     "([a)",
+			syntaxError: synErrBExpUnclosed,
+		},
+		{
+			pattern: "[a-]",
+			ast: genAltNode(
+				newSymbolNode('a'),
+				newSymbolNode('-'),
+			),
+		},
+		{
+			pattern: "[^a-]",
+			ast: genAltNode(
+				newRangeSymbolNode(0x00, 0x2C),
+				newRangeSymbolNode(0x2E, 0x60),
+				newRangeSymbolNode(0x62, 0x10FFFF),
+			),
+		},
+		{
+			pattern: "[-z]",
+			ast: genAltNode(
+				newSymbolNode('-'),
+				newSymbolNode('z'),
+			),
+		},
+		{
+			pattern: "[^-z]",
+			ast: newAltNode(
+				newRangeSymbolNode(0x00, 0x2C),
+				newAltNode(
+					newRangeSymbolNode(0x2E, 0x79),
+					newRangeSymbolNode(0x7B, 0x10FFFF),
+				),
+			),
+		},
+		{
+			pattern: "[-]",
+			ast:     newSymbolNode('-'),
+		},
+		{
+			pattern: "[^-]",
+			ast: genAltNode(
+				newRangeSymbolNode(0x00, 0x2C),
+				newRangeSymbolNode(0x2E, 0x10FFFF),
+			),
+		},
+		{
+			pattern: "[^01]",
+			ast: genAltNode(
+				newRangeSymbolNode(0x00, '0'-1),
+				newRangeSymbolNode('1'+1, 0x10FFFF),
+			),
+		},
+		{
+			pattern: "[^10]",
+			ast: genAltNode(
+				newRangeSymbolNode(0x00, '0'-1),
+				newRangeSymbolNode('1'+1, 0x10FFFF),
+			),
+		},
+		{
+			pattern: "[^a-z]",
+			ast: genAltNode(
+				newRangeSymbolNode(0x00, 'a'-1),
+				newRangeSymbolNode('z'+1, 0x10FFFF),
+			),
+		},
+		{
+			pattern: "[^az]",
+			ast: genAltNode(
+				newRangeSymbolNode(0x00, 'a'-1),
+				genAltNode(
+					newRangeSymbolNode('a'+1, 'z'-1),
+					newRangeSymbolNode('z'+1, 0x10FFFF),
+				),
+			),
+		},
+		{
+			pattern: "\\u{006E}",
+			ast:     newSymbolNode('\u006E'),
+		},
+		{
+			pattern: "\\u{03BD}",
+			ast:     newSymbolNode('\u03BD'),
+		},
+		{
+			pattern: "\\u{306B}",
+			ast:     newSymbolNode('\u306B'),
+		},
+		{
+			pattern: "\\u{01F638}",
+			ast:     newSymbolNode('\U0001F638'),
+		},
+		{
+			pattern: "\\u{0000}",
+			ast:     newSymbolNode('\u0000'),
+		},
+		{
+			pattern: "\\u{10FFFF}",
+			ast:     newSymbolNode('\U0010FFFF'),
+		},
+		{
+			pattern:     "\\u{110000}",
+			syntaxError: synErrCPExpOutOfRange,
+		},
+		{
+			pattern:     "\\u",
+			syntaxError: synErrCPExpInvalidForm,
+		},
+		{
+			pattern:     "\\u{",
+			syntaxError: synErrCPExpInvalidForm,
+		},
+		{
+			pattern:     "\\u{03BD",
+			syntaxError: synErrCPExpInvalidForm,
+		},
+		{
+			pattern:     "\\u{}",
+			syntaxError: synErrCPExpInvalidForm,
+		},
+		{
+			pattern:     "\\p{Letter}",
+			skipTestAST: true,
+		},
+		{
+			pattern:     "\\p{General_Category=Letter}",
+			skipTestAST: true,
+		},
+		{
+			pattern:     "\\p{ Letter }",
+			skipTestAST: true,
+		},
+		{
+			pattern:     "\\p{ General_Category = Letter }",
+			skipTestAST: true,
+		},
+		{
+			pattern:     "\\p",
+			syntaxError: synErrCharPropExpInvalidForm,
+		},
+		{
+			pattern:     "\\p{",
+			syntaxError: synErrCharPropExpInvalidForm,
+		},
+		{
+			pattern:     "\\p{Letter",
+			syntaxError: synErrCharPropExpInvalidForm,
+		},
+		{
+			pattern:     "\\p{General_Category=}",
+			syntaxError: synErrCharPropExpInvalidForm,
+		},
+		{
+			pattern:     "\\p{General_Category=  }",
+			syntaxError: synErrCharPropInvalidSymbol,
+		},
+		{
+			pattern:     "\\p{=Letter}",
+			syntaxError: synErrCharPropExpInvalidForm,
+		},
+		{
+			pattern:     "\\p{  =Letter}",
+			syntaxError: synErrCharPropInvalidSymbol,
+		},
+		{
+			pattern:     "\\p{=}",
+			syntaxError: synErrCharPropExpInvalidForm,
+		},
+		{
+			pattern:     "\\p{}",
+			syntaxError: synErrCharPropExpInvalidForm,
+		},
+		{
+			pattern: "\\f{a2c}",
+			fragments: map[spec.LexKindName]string{
+				"a2c": "abc",
+			},
+			ast: newFragmentNode("a2c",
+				genConcatNode(
+					newSymbolNode('a'),
+					newSymbolNode('b'),
+					newSymbolNode('c'),
+				),
+			),
+		},
+		{
+			pattern: "\\f{ a2c }",
+			fragments: map[spec.LexKindName]string{
+				"a2c": "abc",
+			},
+			ast: newFragmentNode("a2c",
+				genConcatNode(
+					newSymbolNode('a'),
+					newSymbolNode('b'),
+					newSymbolNode('c'),
+				),
+			),
+		},
+		{
+			pattern:     "\\f",
+			syntaxError: synErrFragmentExpInvalidForm,
+		},
+		{
+			pattern:     "\\f{",
+			syntaxError: synErrFragmentExpInvalidForm,
+		},
+		{
+			pattern: "\\f{a2c",
+			fragments: map[spec.LexKindName]string{
+				"a2c": "abc",
+			},
+			syntaxError: synErrFragmentExpInvalidForm,
+		},
+		{
+			pattern: "(a)",
+			ast:     newSymbolNode('a'),
+		},
+		{
+			pattern: "(((a)))",
+			ast:     newSymbolNode('a'),
+		},
+		{
+			pattern:     "a()",
+			syntaxError: synErrGroupNoElem,
+		},
+		{
+			pattern:     "()a",
+			syntaxError: synErrGroupNoElem,
+		},
+		{
+			pattern:     "()",
+			syntaxError: synErrGroupNoElem,
+		},
+		{
+			pattern:     "(",
+			syntaxError: synErrGroupUnclosed,
+		},
+		{
+			pattern:     "a(",
+			syntaxError: synErrGroupUnclosed,
+		},
+		{
+			pattern:     "(a",
+			syntaxError: synErrGroupUnclosed,
+		},
+		{
+			pattern:     "((",
+			syntaxError: synErrGroupUnclosed,
+		},
+		{
+			pattern:     "((a)",
+			syntaxError: synErrGroupUnclosed,
+		},
+		{
+			pattern:     ")",
+			syntaxError: synErrGroupNoInitiator,
+		},
+		{
+			pattern:     "a)",
+			syntaxError: synErrGroupNoInitiator,
+		},
+		{
+			pattern:     ")a",
+			syntaxError: synErrGroupNoInitiator,
+		},
+		{
+			pattern:     "))",
+			syntaxError: synErrGroupNoInitiator,
+		},
+		{
+			pattern:     "(a))",
+			syntaxError: synErrGroupNoInitiator,
+		},
+		{
+			pattern: "Mulder|Scully",
+			ast: genAltNode(
+				genConcatNode(
+					newSymbolNode('M'),
+					newSymbolNode('u'),
+					newSymbolNode('l'),
+					newSymbolNode('d'),
+					newSymbolNode('e'),
+					newSymbolNode('r'),
+				),
+				genConcatNode(
+					newSymbolNode('S'),
+					newSymbolNode('c'),
+					newSymbolNode('u'),
+					newSymbolNode('l'),
+					newSymbolNode('l'),
+					newSymbolNode('y'),
+				),
+			),
+		},
+		{
+			pattern: "Langly|Frohike|Byers",
+			ast: genAltNode(
+				genConcatNode(
+					newSymbolNode('L'),
+					newSymbolNode('a'),
+					newSymbolNode('n'),
+					newSymbolNode('g'),
+					newSymbolNode('l'),
+					newSymbolNode('y'),
+				),
+				genConcatNode(
+					newSymbolNode('F'),
+					newSymbolNode('r'),
+					newSymbolNode('o'),
+					newSymbolNode('h'),
+					newSymbolNode('i'),
+					newSymbolNode('k'),
+					newSymbolNode('e'),
+				),
+				genConcatNode(
+					newSymbolNode('B'),
+					newSymbolNode('y'),
+					newSymbolNode('e'),
+					newSymbolNode('r'),
+					newSymbolNode('s'),
+				),
+			),
+		},
+		{
+			pattern:     "|",
+			syntaxError: synErrAltLackOfOperand,
+		},
+		{
+			pattern:     "||",
+			syntaxError: synErrAltLackOfOperand,
+		},
+		{
+			pattern:     "Mulder|",
+			syntaxError: synErrAltLackOfOperand,
+		},
+		{
+			pattern:     "|Scully",
+			syntaxError: synErrAltLackOfOperand,
+		},
+		{
+			pattern:     "Langly|Frohike|",
+			syntaxError: synErrAltLackOfOperand,
+		},
+		{
+			pattern:     "Langly||Byers",
+			syntaxError: synErrAltLackOfOperand,
+		},
+		{
+			pattern:     "|Frohike|Byers",
+			syntaxError: synErrAltLackOfOperand,
+		},
+		{
+			pattern:     "|Frohike|",
+			syntaxError: synErrAltLackOfOperand,
+		},
+		{
+			pattern:     "Fox(|)Mulder",
+			syntaxError: synErrAltLackOfOperand,
+		},
+		{
+			pattern:     "(Fox|)Mulder",
+			syntaxError: synErrAltLackOfOperand,
+		},
+		{
+			pattern:     "Fox(|Mulder)",
+			syntaxError: synErrAltLackOfOperand,
+		},
+	}
+	for i, tt := range tests {
+		t.Run(fmt.Sprintf("#%v %v", i, tt.pattern), func(t *testing.T) {
+			fragmentTrees := map[spec.LexKindName]CPTree{}
+			for kind, pattern := range tt.fragments {
+				p := NewParser(kind, strings.NewReader(pattern))
+				root, err := p.Parse()
+				if err != nil {
+					t.Fatal(err)
+				}
+
+				fragmentTrees[kind] = root
+			}
+			err := CompleteFragments(fragmentTrees)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			p := NewParser(spec.LexKindName("test"), strings.NewReader(tt.pattern))
+			root, err := p.Parse()
+			if tt.syntaxError != nil {
+				// printCPTree(os.Stdout, root, "", "")
+				if err != ParseErr {
+					t.Fatalf("unexpected error: want: %v, got: %v", ParseErr, err)
+				}
+				_, synErr := p.Error()
+				if synErr != tt.syntaxError {
+					t.Fatalf("unexpected syntax error: want: %v, got: %v", tt.syntaxError, synErr)
+				}
+				if root != nil {
+					t.Fatalf("tree must be nil")
+				}
+			} else {
+				if err != nil {
+					detail, cause := p.Error()
+					t.Fatalf("%v: %v: %v", err, cause, detail)
+				}
+				if root == nil {
+					t.Fatal("tree must be non-nil")
+				}
+
+				complete, err := ApplyFragments(root, fragmentTrees)
+				if err != nil {
+					t.Fatal(err)
+				}
+				if !complete {
+					t.Fatalf("incomplete fragments")
+				}
+
+				// printCPTree(os.Stdout, root, "", "")
+				if !tt.skipTestAST {
+					r := root.(*rootNode)
+					testAST(t, tt.ast, r.tree)
+				}
+			}
+		})
+	}
+}
+
+func TestParse_ContributoryPropertyIsNotExposed(t *testing.T) {
+	for _, cProp := range ucd.ContributoryProperties() {
+		t.Run(fmt.Sprintf("%v", cProp), func(t *testing.T) {
+			p := NewParser(spec.LexKindName("test"), strings.NewReader(fmt.Sprintf(`\p{%v=yes}`, cProp)))
+			root, err := p.Parse()
+			if err == nil {
+				t.Fatalf("expected syntax error: got: nil")
+			}
+			_, synErr := p.Error()
+			if synErr != synErrCharPropUnsupported {
+				t.Fatalf("unexpected syntax error: want: %v, got: %v", synErrCharPropUnsupported, synErr)
+			}
+			if root != nil {
+				t.Fatalf("tree is not nil")
+			}
+		})
+	}
+}
+
+func TestExclude(t *testing.T) {
+	for _, test := range []struct {
+		caption string
+		target  CPTree
+		base    CPTree
+		result  CPTree
+	}{
+		// t.From > b.From && t.To < b.To
+
+		// |t.From - b.From| = 1
+		// |b.To - t.To| = 1
+		//
+		//     Target (t):    +--+
+		//       Base (b): +--+--+--+
+		// Result (b - t): +--+  +--+
+		{
+			caption: "|t.From - b.From| = 1 && |b.To - t.To| = 1",
+			target:  newSymbolNode('1'),
+			base:    newRangeSymbolNode('0', '2'),
+			result: newAltNode(
+				newSymbolNode('0'),
+				newSymbolNode('2'),
+			),
+		},
+		// |t.From - b.From| > 1
+		// |b.To - t.To| > 1
+		//
+		//     Target (t):       +--+
+		//       Base (b): +--+--+--+--+--+
+		// Result (b - t): +--+--+  +--+--+
+		{
+			caption: "|t.From - b.From| > 1 && |b.To - t.To| > 1",
+			target:  newSymbolNode('2'),
+			base:    newRangeSymbolNode('0', '4'),
+			result: newAltNode(
+				newRangeSymbolNode('0', '1'),
+				newRangeSymbolNode('3', '4'),
+			),
+		},
+
+		// t.From <= b.From && t.To >= b.From && t.To < b.To
+
+		// |b.From - t.From| = 0
+		// |t.To - b.From| = 0
+		// |b.To - t.To| = 1
+		//
+		//     Target (t): +--+
+		//       Base (b): +--+--+
+		// Result (b - t):    +--+
+		{
+			caption: "|b.From - t.From| = 0 && |t.To - b.From| = 0 && |b.To - t.To| = 1",
+			target:  newSymbolNode('0'),
+			base:    newRangeSymbolNode('0', '1'),
+			result:  newSymbolNode('1'),
+		},
+		// |b.From - t.From| = 0
+		// |t.To - b.From| = 0
+		// |b.To - t.To| > 1
+		//
+		//     Target (t): +--+
+		//       Base (b): +--+--+--+
+		// Result (b - t):    +--+--+
+		{
+			caption: "|b.From - t.From| = 0 && |t.To - b.From| = 0 && |b.To - t.To| > 1",
+			target:  newSymbolNode('0'),
+			base:    newRangeSymbolNode('0', '2'),
+			result:  newRangeSymbolNode('1', '2'),
+		},
+		// |b.From - t.From| = 0
+		// |t.To - b.From| > 0
+		// |b.To - t.To| = 1
+		//
+		//     Target (t): +--+--+
+		//       Base (b): +--+--+--+
+		// Result (b - t):       +--+
+		{
+			caption: "|b.From - t.From| = 0 && |t.To - b.From| > 0 && |b.To - t.To| = 1",
+			target:  newRangeSymbolNode('0', '1'),
+			base:    newRangeSymbolNode('0', '2'),
+			result:  newSymbolNode('2'),
+		},
+		// |b.From - t.From| = 0
+		// |t.To - b.From| > 0
+		// |b.To - t.To| > 1
+		//
+		//     Target (t): +--+--+
+		//       Base (b): +--+--+--+--+
+		// Result (b - t):       +--+--+
+		{
+			caption: "|b.From - t.From| = 0 && |t.To - b.From| > 0 && |b.To - t.To| > 1",
+			target:  newRangeSymbolNode('0', '1'),
+			base:    newRangeSymbolNode('0', '3'),
+			result:  newRangeSymbolNode('2', '3'),
+		},
+		// |b.From - t.From| > 0
+		// |t.To - b.From| = 0
+		// |b.To - t.To| = 1
+		//
+		//     Target (t): +--+--+
+		//       Base (b):    +--+--+
+		// Result (b - t):       +--+
+		{
+			caption: "|b.From - t.From| > 0 && |t.To - b.From| = 0 && |b.To - t.To| = 1",
+			target:  newRangeSymbolNode('0', '1'),
+			base:    newRangeSymbolNode('1', '2'),
+			result:  newSymbolNode('2'),
+		},
+		// |b.From - t.From| > 0
+		// |t.To - b.From| = 0
+		// |b.To - t.To| > 1
+		//
+		//     Target (t): +--+--+
+		//       Base (b):    +--+--+--+
+		// Result (b - t):       +--+--+
+		{
+			caption: "|b.From - t.From| > 0 && |t.To - b.From| = 0 && |b.To - t.To| > 1",
+			target:  newRangeSymbolNode('0', '1'),
+			base:    newRangeSymbolNode('1', '3'),
+			result:  newRangeSymbolNode('2', '3'),
+		},
+		// |b.From - t.From| > 0
+		// |t.To - b.From| > 0
+		// |b.To - t.To| = 1
+		//
+		//     Target (t): +--+--+--+
+		//       Base (b):    +--+--+--+
+		// Result (b - t):          +--+
+		{
+			caption: "|b.From - t.From| > 0 && |t.To - b.From| > 0 && |b.To - t.To| = 1",
+			target:  newRangeSymbolNode('0', '2'),
+			base:    newRangeSymbolNode('1', '3'),
+			result:  newSymbolNode('3'),
+		},
+		// |b.From - t.From| > 0
+		// |t.To - b.From| > 0
+		// |b.To - t.To| > 1
+		//
+		//     Target (t): +--+--+--+
+		//       Base (b):    +--+--+--+--+
+		// Result (b - t):          +--+--+
+		{
+			caption: "|b.From - t.From| > 0 && |t.To - b.From| > 0 && |b.To - t.To| > 1",
+			target:  newRangeSymbolNode('0', '2'),
+			base:    newRangeSymbolNode('1', '4'),
+			result:  newRangeSymbolNode('3', '4'),
+		},
+
+		// t.From > b.From && t.From <= b.To && t.To >= b.To
+
+		// |t.From - b.From| = 1
+		// |b.To - t.From| = 0
+		// |t.To - b.To| = 0
+		//
+		//     Target (t):    +--+
+		//       Base (b): +--+--+
+		// Result (b - t): +--+
+		{
+			caption: "|t.From - b.From| = 1 && |b.To - t.From| = 0 && |t.To - b.To| = 0",
+			target:  newSymbolNode('1'),
+			base:    newRangeSymbolNode('0', '1'),
+			result:  newSymbolNode('0'),
+		},
+		// |t.From - b.From| = 1
+		// |b.To - t.From| = 0
+		// |t.To - b.To| > 0
+		//
+		//     Target (t):    +--+--+
+		//       Base (b): +--+--+
+		// Result (b - t): +--+
+		{
+			caption: "|t.From - b.From| = 1 && |b.To - t.From| = 0 && |t.To - b.To| > 0",
+			target:  newRangeSymbolNode('1', '2'),
+			base:    newRangeSymbolNode('0', '1'),
+			result:  newSymbolNode('0'),
+		},
+		// |t.From - b.From| = 1
+		// |b.To - t.From| > 0
+		// |t.To - b.To| = 0
+		//
+		//     Target (t):    +--+--+
+		//       Base (b): +--+--+--+
+		// Result (b - t): +--+
+		{
+			caption: "|t.From - b.From| = 1 && |b.To - t.From| > 0 && |t.To - b.To| = 0",
+			target:  newRangeSymbolNode('1', '2'),
+			base:    newRangeSymbolNode('0', '2'),
+			result:  newSymbolNode('0'),
+		},
+		// |t.From - b.From| = 1
+		// |b.To - t.From| > 0
+		// |t.To - b.To| > 0
+		//
+		//     Target (t):    +--+--+--+
+		//       Base (b): +--+--+--+
+		// Result (b - t): +--+
+		{
+			caption: "|t.From - b.From| = 1 && |b.To - t.From| > 0 && |t.To - b.To| > 0",
+			target:  newRangeSymbolNode('1', '3'),
+			base:    newRangeSymbolNode('0', '2'),
+			result:  newSymbolNode('0'),
+		},
+		// |t.From - b.From| > 1
+		// |b.To - t.From| = 0
+		// |t.To - b.To| = 0
+		//
+		//     Target (t):       +--+
+		//       Base (b): +--+--+--+
+		// Result (b - t): +--+--+
+		{
+			caption: "|t.From - b.From| > 1 && |b.To - t.From| = 0 && |t.To - b.To| = 0",
+			target:  newSymbolNode('2'),
+			base:    newRangeSymbolNode('0', '2'),
+			result:  newRangeSymbolNode('0', '1'),
+		},
+		// |t.From - b.From| > 1
+		// |b.To - t.From| = 0
+		// |t.To - b.To| > 0
+		//
+		//     Target (t):       +--+--+
+		//       Base (b): +--+--+--+
+		// Result (b - t): +--+--+
+		{
+			caption: "|t.From - b.From| > 1 && |b.To - t.From| = 0 && |t.To - b.To| > 0",
+			target:  newRangeSymbolNode('2', '3'),
+			base:    newRangeSymbolNode('0', '2'),
+			result:  newRangeSymbolNode('0', '1'),
+		},
+		// |t.From - b.From| > 1
+		// |b.To - t.From| > 0
+		// |t.To - b.To| = 0
+		//
+		//     Target (t):       +--+--+
+		//       Base (b): +--+--+--+--+
+		// Result (b - t): +--+--+
+		{
+			caption: "|t.From - b.From| > 1 && |b.To - t.From| > 0 && |t.To - b.To| = 0",
+			target:  newRangeSymbolNode('2', '3'),
+			base:    newRangeSymbolNode('0', '3'),
+			result:  newRangeSymbolNode('0', '1'),
+		},
+		// |t.From - b.From| > 1
+		// |b.To - t.From| > 0
+		// |t.To - b.To| > 0
+		//
+		//     Target (t):       +--+--+--+
+		//       Base (b): +--+--+--+--+
+		// Result (b - t): +--+--+
+		{
+			caption: "|t.From - b.From| > 1 && |b.To - t.From| > 0 && |t.To - b.To| > 0",
+			target:  newRangeSymbolNode('2', '4'),
+			base:    newRangeSymbolNode('0', '3'),
+			result:  newRangeSymbolNode('0', '1'),
+		},
+
+		// t.From <= b.From && t.To >= b.To
+
+		// |b.From - t.From| = 0
+		// |t.To - b.To| = 0
+		//
+		//     Target (t): +--+
+		//       Base (b): +--+
+		// Result (b - t): N/A
+		{
+			caption: "|b.From - t.From| = 0 && |t.To - b.To| = 0",
+			target:  newSymbolNode('0'),
+			base:    newSymbolNode('0'),
+			result:  nil,
+		},
+		// |b.From - t.From| = 0
+		// |t.To - b.To| > 0
+		//
+		//     Target (t): +--+--+
+		//       Base (b): +--+
+		// Result (b - t): N/A
+		{
+			caption: "|b.From - t.From| = 0 && |t.To - b.To| > 0",
+			target:  newRangeSymbolNode('0', '1'),
+			base:    newSymbolNode('0'),
+			result:  nil,
+		},
+		// |b.From - t.From| > 0
+		// |t.To - b.To| = 0
+		//
+		//     Target (t): +--+--+
+		//       Base (b):    +--+
+		// Result (b - t): N/A
+		{
+			caption: "|b.From - t.From| > 0 && |t.To - b.To| = 0",
+			target:  newRangeSymbolNode('0', '1'),
+			base:    newSymbolNode('1'),
+			result:  nil,
+		},
+		// |b.From - t.From| > 0
+		// |t.To - b.To| > 0
+		//
+		//     Target (t): +--+--+--+
+		//       Base (b):    +--+
+		// Result (b - t): N/A
+		{
+			caption: "|b.From - t.From| > 0 && |t.To - b.To| > 0",
+			target:  newRangeSymbolNode('0', '2'),
+			base:    newSymbolNode('1'),
+			result:  nil,
+		},
+
+		// Others
+
+		// |b.From - t.From| = 1
+		//
+		//     Target (t): +--+
+		//       Base (b):    +--+
+		// Result (b - t):    +--+
+		{
+			caption: "|b.From - t.From| = 1",
+			target:  newSymbolNode('0'),
+			base:    newSymbolNode('1'),
+			result:  newSymbolNode('1'),
+		},
+		// |b.From - t.From| > 1
+		//
+		//     Target (t): +--+
+		//       Base (b):       +--+
+		// Result (b - t):       +--+
+		{
+			caption: "|b.From - t.From| > 1",
+			target:  newSymbolNode('0'),
+			base:    newSymbolNode('2'),
+			result:  newSymbolNode('2'),
+		},
+		// |t.To - b.To| = 1
+		//
+		//     Target (t):    +--+
+		//       Base (b): +--+
+		// Result (b - t): +--+
+		{
+			caption: "|t.To - b.To| = 1",
+			target:  newSymbolNode('1'),
+			base:    newSymbolNode('0'),
+			result:  newSymbolNode('0'),
+		},
+		// |t.To - b.To| > 1
+		//
+		//     Target (t):       +--+
+		//       Base (b): +--+
+		// Result (b - t): +--+
+		{
+			caption: "|t.To - b.To| > 1",
+			target:  newSymbolNode('2'),
+			base:    newSymbolNode('0'),
+			result:  newSymbolNode('0'),
+		},
+	} {
+		t.Run(test.caption, func(t *testing.T) {
+			r := exclude(test.target, test.base)
+			testAST(t, test.result, r)
+		})
+	}
+}
+
+func testAST(t *testing.T, expected, actual CPTree) {
+	t.Helper()
+
+	aTy := reflect.TypeOf(actual)
+	eTy := reflect.TypeOf(expected)
+	if eTy != aTy {
+		t.Fatalf("unexpected node: want: %+v, got: %+v", eTy, aTy)
+	}
+
+	if actual == nil {
+		return
+	}
+
+	switch e := expected.(type) {
+	case *symbolNode:
+		a := actual.(*symbolNode)
+		if a.From != e.From || a.To != e.To {
+			t.Fatalf("unexpected node: want: %+v, got: %+v", e, a)
+		}
+	}
+	eLeft, eRight := expected.children()
+	aLeft, aRight := actual.children()
+	testAST(t, eLeft, aLeft)
+	testAST(t, eRight, aRight)
+}
diff --git a/tests/unit/urubu/grammar/symbol.go b/tests/unit/urubu/grammar/symbol.go
new file mode 100644
index 0000000..31c3edd
--- /dev/null
+++ b/tests/unit/urubu/grammar/symbol.go
@@ -0,0 +1,159 @@
+package symbol
+
+import "testing"
+
+func TestSymbol(t *testing.T) {
+	tab := NewSymbolTable()
+	w := tab.Writer()
+	_, _ = w.RegisterStartSymbol("expr'")
+	_, _ = w.RegisterNonTerminalSymbol("expr")
+	_, _ = w.RegisterNonTerminalSymbol("term")
+	_, _ = w.RegisterNonTerminalSymbol("factor")
+	_, _ = w.RegisterTerminalSymbol("id")
+	_, _ = w.RegisterTerminalSymbol("add")
+	_, _ = w.RegisterTerminalSymbol("mul")
+	_, _ = w.RegisterTerminalSymbol("l_paren")
+	_, _ = w.RegisterTerminalSymbol("r_paren")
+
+	nonTermTexts := []string{
+		"", // Nil
+		"expr'",
+		"expr",
+		"term",
+		"factor",
+	}
+
+	termTexts := []string{
+		"",            // Nil
+		symbolNameEOF, // EOF
+		"id",
+		"add",
+		"mul",
+		"l_paren",
+		"r_paren",
+	}
+
+	tests := []struct {
+		text          string
+		isNil         bool
+		isStart       bool
+		isEOF         bool
+		isNonTerminal bool
+		isTerminal    bool
+	}{
+		{
+			text:          "expr'",
+			isStart:       true,
+			isNonTerminal: true,
+		},
+		{
+			text:          "expr",
+			isNonTerminal: true,
+		},
+		{
+			text:          "term",
+			isNonTerminal: true,
+		},
+		{
+			text:          "factor",
+			isNonTerminal: true,
+		},
+		{
+			text:       "id",
+			isTerminal: true,
+		},
+		{
+			text:       "add",
+			isTerminal: true,
+		},
+		{
+			text:       "mul",
+			isTerminal: true,
+		},
+		{
+			text:       "l_paren",
+			isTerminal: true,
+		},
+		{
+			text:       "r_paren",
+			isTerminal: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.text, func(t *testing.T) {
+			r := tab.Reader()
+			sym, ok := r.ToSymbol(tt.text)
+			if !ok {
+				t.Fatalf("symbol was not found")
+			}
+			testSymbolProperty(t, sym, tt.isNil, tt.isStart, tt.isEOF, tt.isNonTerminal, tt.isTerminal)
+			text, ok := r.ToText(sym)
+			if !ok {
+				t.Fatalf("text was not found")
+			}
+			if text != tt.text {
+				t.Fatalf("unexpected text representation; want: %v, got: %v", tt.text, text)
+			}
+		})
+	}
+
+	t.Run("EOF", func(t *testing.T) {
+		testSymbolProperty(t, SymbolEOF, false, false, true, false, true)
+	})
+
+	t.Run("Nil", func(t *testing.T) {
+		testSymbolProperty(t, SymbolNil, true, false, false, false, false)
+	})
+
+	t.Run("texts of non-terminals", func(t *testing.T) {
+		r := tab.Reader()
+		ts, err := r.NonTerminalTexts()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if len(ts) != len(nonTermTexts) {
+			t.Fatalf("unexpected non-terminal count; want: %v (%#v), got: %v (%#v)", len(nonTermTexts), nonTermTexts, len(ts), ts)
+		}
+		for i, text := range ts {
+			if text != nonTermTexts[i] {
+				t.Fatalf("unexpected non-terminal; want: %v, got: %v", nonTermTexts[i], text)
+			}
+		}
+	})
+
+	t.Run("texts of terminals", func(t *testing.T) {
+		r := tab.Reader()
+		ts, err := r.TerminalTexts()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if len(ts) != len(termTexts) {
+			t.Fatalf("unexpected terminal count; want: %v (%#v), got: %v (%#v)", len(termTexts), termTexts, len(ts), ts)
+		}
+		for i, text := range ts {
+			if text != termTexts[i] {
+				t.Fatalf("unexpected terminal; want: %v, got: %v", termTexts[i], text)
+			}
+		}
+	})
+}
+
+func testSymbolProperty(t *testing.T, sym Symbol, isNil, isStart, isEOF, isNonTerminal, isTerminal bool) {
+	t.Helper()
+
+	if v := sym.IsNil(); v != isNil {
+		t.Fatalf("isNil property is mismatched; want: %v, got: %v", isNil, v)
+	}
+	if v := sym.IsStart(); v != isStart {
+		t.Fatalf("isStart property is mismatched; want: %v, got: %v", isStart, v)
+	}
+	if v := sym.isEOF(); v != isEOF {
+		t.Fatalf("isEOF property is mismatched; want: %v, got: %v", isEOF, v)
+	}
+	if v := sym.isNonTerminal(); v != isNonTerminal {
+		t.Fatalf("isNonTerminal property is mismatched; want: %v, got: %v", isNonTerminal, v)
+	}
+	if v := sym.IsTerminal(); v != isTerminal {
+		t.Fatalf("isTerminal property is mismatched; want: %v, got: %v", isTerminal, v)
+	}
+}