Do the same single file consolidation on tests

1 files changed, 4647 insertions, 0 deletions

diff --git a/tests/unit/grammar.go b/tests/unit/grammar.go
new file mode 100644
index 0000000..3743b23
--- /dev/null
+++ b/tests/unit/grammar.go
@@ -0,0 +1,4647 @@
+package grammar
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	verr "urubu/error"
+	"urubu/grammar/symbol"
+	"urubu/spec/grammar/parser"
+)
+
+type first struct {
+	lhs     string
+	num     int
+	dot     int
+	symbols []string
+	empty   bool
+}
+
+func TestGenFirst(t *testing.T) {
+	tests := []struct {
+		caption string
+		src     string
+		first   []first
+	}{
+		{
+			caption: "productions contain only non-empty productions",
+			src: `
+#name test;
+
+expr
+    : expr add term
+    | term
+    ;
+term
+    : term mul factor
+    | factor
+    ;
+factor
+    : l_paren expr r_paren
+    | id
+    ;
+add: "\+";
+mul: "\*";
+l_paren: "\(";
+r_paren: "\)";
+id: "[A-Za-z_][0-9A-Za-z_]*";
+`,
+			first: []first{
+				{lhs: "expr'", num: 0, dot: 0, symbols: []string{"l_paren", "id"}},
+				{lhs: "expr", num: 0, dot: 0, symbols: []string{"l_paren", "id"}},
+				{lhs: "expr", num: 0, dot: 1, symbols: []string{"add"}},
+				{lhs: "expr", num: 0, dot: 2, symbols: []string{"l_paren", "id"}},
+				{lhs: "expr", num: 1, dot: 0, symbols: []string{"l_paren", "id"}},
+				{lhs: "term", num: 0, dot: 0, symbols: []string{"l_paren", "id"}},
+				{lhs: "term", num: 0, dot: 1, symbols: []string{"mul"}},
+				{lhs: "term", num: 0, dot: 2, symbols: []string{"l_paren", "id"}},
+				{lhs: "term", num: 1, dot: 0, symbols: []string{"l_paren", "id"}},
+				{lhs: "factor", num: 0, dot: 0, symbols: []string{"l_paren"}},
+				{lhs: "factor", num: 0, dot: 1, symbols: []string{"l_paren", "id"}},
+				{lhs: "factor", num: 0, dot: 2, symbols: []string{"r_paren"}},
+				{lhs: "factor", num: 1, dot: 0, symbols: []string{"id"}},
+			},
+		},
+		{
+			caption: "productions contain the empty start production",
+			src: `
+#name test;
+
+s
+    :
+    ;
+`,
+			first: []first{
+				{lhs: "s'", num: 0, dot: 0, symbols: []string{}, empty: true},
+				{lhs: "s", num: 0, dot: 0, symbols: []string{}, empty: true},
+			},
+		},
+		{
+			caption: "productions contain an empty production",
+			src: `
+#name test;
+
+s
+    : foo bar
+    ;
+foo
+    :
+    ;
+bar: "bar";
+`,
+			first: []first{
+				{lhs: "s'", num: 0, dot: 0, symbols: []string{"bar"}, empty: false},
+				{lhs: "s", num: 0, dot: 0, symbols: []string{"bar"}, empty: false},
+				{lhs: "foo", num: 0, dot: 0, symbols: []string{}, empty: true},
+			},
+		},
+		{
+			caption: "a start production contains a non-empty alternative and empty alternative",
+			src: `
+#name test;
+
+s
+    : foo
+    |
+    ;
+foo: "foo";
+`,
+			first: []first{
+				{lhs: "s'", num: 0, dot: 0, symbols: []string{"foo"}, empty: true},
+				{lhs: "s", num: 0, dot: 0, symbols: []string{"foo"}},
+				{lhs: "s", num: 1, dot: 0, symbols: []string{}, empty: true},
+			},
+		},
+		{
+			caption: "a production contains non-empty alternative and empty alternative",
+			src: `
+#name test;
+
+s
+    : foo
+    ;
+foo
+    : bar
+    |
+    ;
+bar: "bar";
+`,
+			first: []first{
+				{lhs: "s'", num: 0, dot: 0, symbols: []string{"bar"}, empty: true},
+				{lhs: "s", num: 0, dot: 0, symbols: []string{"bar"}, empty: true},
+				{lhs: "foo", num: 0, dot: 0, symbols: []string{"bar"}},
+				{lhs: "foo", num: 1, dot: 0, symbols: []string{}, empty: true},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.caption, func(t *testing.T) {
+			fst, gram := genActualFirst(t, tt.src)
+
+			for _, ttFirst := range tt.first {
+				lhsSym, ok := gram.symbolTable.ToSymbol(ttFirst.lhs)
+				if !ok {
+					t.Fatalf("a symbol was not found; symbol: %v", ttFirst.lhs)
+				}
+
+				prod, ok := gram.productionSet.findByLHS(lhsSym)
+				if !ok {
+					t.Fatalf("a production was not found; LHS: %v (%v)", ttFirst.lhs, lhsSym)
+				}
+
+				actualFirst, err := fst.find(prod[ttFirst.num], ttFirst.dot)
+				if err != nil {
+					t.Fatalf("failed to get a FIRST set; LHS: %v (%v), num: %v, dot: %v, error: %v", ttFirst.lhs, lhsSym, ttFirst.num, ttFirst.dot, err)
+				}
+
+				expectedFirst := genExpectedFirstEntry(t, ttFirst.symbols, ttFirst.empty, gram.symbolTable)
+
+				testFirst(t, actualFirst, expectedFirst)
+			}
+		})
+	}
+}
+
+func genActualFirst(t *testing.T, src string) (*firstSet, *Grammar) {
+	ast, err := parser.Parse(strings.NewReader(src))
+	if err != nil {
+		t.Fatal(err)
+	}
+	b := GrammarBuilder{
+		AST: ast,
+	}
+	gram, err := b.build()
+	if err != nil {
+		t.Fatal(err)
+	}
+	fst, err := genFirstSet(gram.productionSet)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if fst == nil {
+		t.Fatal("genFiest returned nil without any error")
+	}
+
+	return fst, gram
+}
+
+func genExpectedFirstEntry(t *testing.T, symbols []string, empty bool, symTab *symbol.SymbolTableReader) *firstEntry {
+	t.Helper()
+
+	entry := newFirstEntry()
+	if empty {
+		entry.addEmpty()
+	}
+	for _, sym := range symbols {
+		symSym, ok := symTab.ToSymbol(sym)
+		if !ok {
+			t.Fatalf("a symbol was not found; symbol: %v", sym)
+		}
+		entry.add(symSym)
+	}
+
+	return entry
+}
+
+func testFirst(t *testing.T, actual, expected *firstEntry) {
+	if actual.empty != expected.empty {
+		t.Errorf("empty is mismatched\nwant: %v\ngot: %v", expected.empty, actual.empty)
+	}
+
+	if len(actual.symbols) != len(expected.symbols) {
+		t.Fatalf("invalid FIRST set\nwant: %+v\ngot: %+v", expected.symbols, actual.symbols)
+	}
+
+	for eSym := range expected.symbols {
+		if _, ok := actual.symbols[eSym]; !ok {
+			t.Fatalf("invalid FIRST set\nwant: %+v\ngot: %+v", expected.symbols, actual.symbols)
+		}
+	}
+}
+
+func TestGrammarBuilderOK(t *testing.T) {
+	type okTest struct {
+		caption  string
+		specSrc  string
+		validate func(t *testing.T, g *Grammar)
+	}
+
+	nameTests := []*okTest{
+		{
+			caption: "the `#name` can be the same identifier as a non-terminal symbol",
+			specSrc: `
+#name s;
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				expected := "s"
+				if g.name != expected {
+					t.Fatalf("unexpected name: want: %v, got: %v", expected, g.name)
+				}
+			},
+		},
+		{
+			caption: "the `#name` can be the same identifier as a terminal symbol",
+			specSrc: `
+#name foo;
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				expected := "foo"
+				if g.name != expected {
+					t.Fatalf("unexpected name: want: %v, got: %v", expected, g.name)
+				}
+			},
+		},
+		{
+			caption: "the `#name` can be the same identifier as the error symbol",
+			specSrc: `
+#name error;
+
+s
+    : foo
+    | error
+    ;
+
+foo
+    : 'foo';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				expected := "error"
+				if g.name != expected {
+					t.Fatalf("unexpected name: want: %v, got: %v", expected, g.name)
+				}
+			},
+		},
+		{
+			caption: "the `#name` can be the same identifier as a fragment",
+			specSrc: `
+#name f;
+
+s
+    : foo
+    ;
+
+foo
+    : "\f{f}";
+fragment f
+    : 'foo';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				expected := "f"
+				if g.name != expected {
+					t.Fatalf("unexpected name: want: %v, got: %v", expected, g.name)
+				}
+			},
+		},
+	}
+
+	modeTests := []*okTest{
+		{
+			caption: "a `#mode` can be the same identifier as a non-terminal symbol",
+			specSrc: `
+#name test;
+
+s
+    : foo bar
+    ;
+
+foo #push s
+    : 'foo';
+bar #mode s
+    : 'bar';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				kind := "bar"
+				expectedMode := "s"
+				for _, e := range g.lexSpec.Entries {
+					if e.Kind.String() == kind && e.Modes[0].String() == expectedMode {
+						return
+					}
+				}
+				t.Fatalf("symbol having expected mode was not found: want: %v #mode %v", kind, expectedMode)
+			},
+		},
+		{
+			caption: "a `#mode` can be the same identifier as a terminal symbol",
+			specSrc: `
+#name test;
+
+s
+    : foo bar
+    ;
+
+foo #push bar
+    : 'foo';
+bar #mode bar
+    : 'bar';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				kind := "bar"
+				expectedMode := "bar"
+				for _, e := range g.lexSpec.Entries {
+					if e.Kind.String() == kind && e.Modes[0].String() == expectedMode {
+						return
+					}
+				}
+				t.Fatalf("symbol having expected mode was not found: want: %v #mode %v", kind, expectedMode)
+			},
+		},
+		{
+			caption: "a `#mode` can be the same identifier as the error symbol",
+			specSrc: `
+#name test;
+
+s
+    : foo bar
+    | error
+    ;
+
+foo #push error
+    : 'foo';
+bar #mode error
+    : 'bar';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				kind := "bar"
+				expectedMode := "error"
+				for _, e := range g.lexSpec.Entries {
+					if e.Kind.String() == kind && e.Modes[0].String() == expectedMode {
+						return
+					}
+				}
+				t.Fatalf("symbol having expected mode was not found: want: %v #mode %v", kind, expectedMode)
+			},
+		},
+		{
+			caption: "a `#mode` can be the same identifier as a fragment",
+			specSrc: `
+#name test;
+
+s
+    : foo bar
+    ;
+
+foo #push f
+    : "\f{f}";
+bar #mode f
+    : 'bar';
+fragment f
+    : 'foo';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				kind := "bar"
+				expectedMode := "f"
+				for _, e := range g.lexSpec.Entries {
+					if e.Kind.String() == kind && e.Modes[0].String() == expectedMode {
+						return
+					}
+				}
+				t.Fatalf("symbol having expected mode was not found: want: %v #mode %v", kind, expectedMode)
+			},
+		},
+	}
+
+	precTests := []*okTest{
+		{
+			caption: "a `#prec` allows the empty directive group",
+			specSrc: `
+#name test;
+
+#prec ();
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+		},
+		{
+			caption: "a `#left` directive gives a precedence and the left associativity to specified terminal symbols",
+			specSrc: `
+#name test;
+
+#prec (
+    #left foo bar
+);
+
+s
+    : foo bar baz
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+baz
+    : 'baz';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				var fooPrec int
+				var fooAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("foo")
+					fooPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					fooAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				if fooPrec != 1 || fooAssoc != assocTypeLeft {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 1, assocTypeLeft, fooPrec, fooAssoc)
+				}
+				var barPrec int
+				var barAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("bar")
+					barPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					barAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				if barPrec != 1 || barAssoc != assocTypeLeft {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 1, assocTypeLeft, barPrec, barAssoc)
+				}
+				var bazPrec int
+				var bazAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("baz")
+					bazPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					bazAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				if bazPrec != precNil || bazAssoc != assocTypeNil {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", precNil, assocTypeNil, bazPrec, bazAssoc)
+				}
+			},
+		},
+		{
+			caption: "a `#right` directive gives a precedence and the right associativity to specified terminal symbols",
+			specSrc: `
+#name test;
+
+#prec (
+    #right foo bar
+);
+
+s
+    : foo bar baz
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+baz
+    : 'baz';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				var fooPrec int
+				var fooAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("foo")
+					fooPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					fooAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				if fooPrec != 1 || fooAssoc != assocTypeRight {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 1, assocTypeRight, fooPrec, fooAssoc)
+				}
+				var barPrec int
+				var barAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("bar")
+					barPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					barAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				if barPrec != 1 || barAssoc != assocTypeRight {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 1, assocTypeRight, barPrec, barAssoc)
+				}
+				var bazPrec int
+				var bazAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("baz")
+					bazPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					bazAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				if bazPrec != precNil || bazAssoc != assocTypeNil {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", precNil, assocTypeNil, bazPrec, bazAssoc)
+				}
+			},
+		},
+		{
+			caption: "an `#assign` directive gives only a precedence to specified terminal symbols",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign foo bar
+);
+
+s
+    : foo bar baz
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+baz
+    : 'baz';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				var fooPrec int
+				var fooAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("foo")
+					fooPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					fooAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				if fooPrec != 1 || fooAssoc != assocTypeNil {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 1, assocTypeNil, fooPrec, fooAssoc)
+				}
+				var barPrec int
+				var barAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("bar")
+					barPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					barAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				if barPrec != 1 || barAssoc != assocTypeNil {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 1, assocTypeNil, barPrec, barAssoc)
+				}
+				var bazPrec int
+				var bazAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("baz")
+					bazPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					bazAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				if bazPrec != precNil || bazAssoc != assocTypeNil {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", precNil, assocTypeNil, bazPrec, bazAssoc)
+				}
+			},
+		},
+		{
+			caption: "a production has the same precedence and associativity as the right-most terminal symbol",
+			specSrc: `
+#name test;
+
+#prec (
+    #left foo
+);
+
+s
+    : foo bar // This alternative has the same precedence and associativity as the right-most terminal symbol 'bar', not 'foo'.
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				var barPrec int
+				var barAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("bar")
+					barPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					barAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				var sPrec int
+				var sAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("s")
+					ps, _ := g.productionSet.findByLHS(s)
+					sPrec = g.precAndAssoc.productionPredence(ps[0].num)
+					sAssoc = g.precAndAssoc.productionAssociativity(ps[0].num)
+				}
+				if barPrec != precNil || barAssoc != assocTypeNil {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", precNil, assocTypeNil, barPrec, barAssoc)
+				}
+				if sPrec != barPrec || sAssoc != barAssoc {
+					t.Fatalf("unexpected production precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", barPrec, barAssoc, sPrec, sAssoc)
+				}
+			},
+		},
+		{
+			caption: "a production has the same precedence and associativity as the right-most terminal symbol",
+			specSrc: `
+#name test;
+
+#prec (
+    #left foo
+    #right bar
+);
+
+s
+    : foo bar // This alternative has the same precedence and associativity as the right-most terminal symbol 'bar'.
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				var barPrec int
+				var barAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("bar")
+					barPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					barAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				var sPrec int
+				var sAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("s")
+					ps, _ := g.productionSet.findByLHS(s)
+					sPrec = g.precAndAssoc.productionPredence(ps[0].num)
+					sAssoc = g.precAndAssoc.productionAssociativity(ps[0].num)
+				}
+				if barPrec != 2 || barAssoc != assocTypeRight {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 2, assocTypeRight, barPrec, barAssoc)
+				}
+				if sPrec != barPrec || sAssoc != barAssoc {
+					t.Fatalf("unexpected production precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", barPrec, barAssoc, sPrec, sAssoc)
+				}
+			},
+		},
+		{
+			caption: "even if a non-terminal symbol apears to a terminal symbol, a production inherits precedence and associativity from the right-most terminal symbol, not from the non-terminal symbol",
+			specSrc: `
+#name test;
+
+#prec (
+    #left foo
+    #right bar
+);
+
+s
+    : foo a // This alternative has the same precedence and associativity as the right-most terminal symbol 'foo', not 'a'.
+    ;
+a
+    : bar
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				var fooPrec int
+				var fooAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("foo")
+					fooPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					fooAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				var barPrec int
+				var barAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("bar")
+					barPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					barAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				var aPrec int
+				var aAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("a")
+					ps, _ := g.productionSet.findByLHS(s)
+					aPrec = g.precAndAssoc.productionPredence(ps[0].num)
+					aAssoc = g.precAndAssoc.productionAssociativity(ps[0].num)
+				}
+				var sPrec int
+				var sAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("s")
+					ps, _ := g.productionSet.findByLHS(s)
+					sPrec = g.precAndAssoc.productionPredence(ps[0].num)
+					sAssoc = g.precAndAssoc.productionAssociativity(ps[0].num)
+				}
+				if fooPrec != 1 || fooAssoc != assocTypeLeft {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 1, assocTypeLeft, fooPrec, fooAssoc)
+				}
+				if barPrec != 2 || barAssoc != assocTypeRight {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 2, assocTypeRight, barPrec, barAssoc)
+				}
+				if aPrec != barPrec || aAssoc != barAssoc {
+					t.Fatalf("unexpected production precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", barPrec, barAssoc, aPrec, aAssoc)
+				}
+				if sPrec != fooPrec || sAssoc != fooAssoc {
+					t.Fatalf("unexpected production precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", fooPrec, fooAssoc, sPrec, sAssoc)
+				}
+			},
+		},
+		{
+			caption: "each alternative in the same production can have its own precedence and associativity",
+			specSrc: `
+#name test;
+
+#prec (
+    #left foo
+    #right bar
+    #assign baz
+);
+
+s
+    : foo
+    | bar
+    | baz
+    | bra
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+baz
+    : 'baz';
+bra
+    : 'bra';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				var alt1Prec int
+				var alt1Assoc assocType
+				var alt2Prec int
+				var alt2Assoc assocType
+				var alt3Prec int
+				var alt3Assoc assocType
+				var alt4Prec int
+				var alt4Assoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("s")
+					ps, _ := g.productionSet.findByLHS(s)
+					alt1Prec = g.precAndAssoc.productionPredence(ps[0].num)
+					alt1Assoc = g.precAndAssoc.productionAssociativity(ps[0].num)
+					alt2Prec = g.precAndAssoc.productionPredence(ps[1].num)
+					alt2Assoc = g.precAndAssoc.productionAssociativity(ps[1].num)
+					alt3Prec = g.precAndAssoc.productionPredence(ps[2].num)
+					alt3Assoc = g.precAndAssoc.productionAssociativity(ps[2].num)
+					alt4Prec = g.precAndAssoc.productionPredence(ps[3].num)
+					alt4Assoc = g.precAndAssoc.productionAssociativity(ps[3].num)
+				}
+				if alt1Prec != 1 || alt1Assoc != assocTypeLeft {
+					t.Fatalf("unexpected production precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 1, assocTypeLeft, alt1Prec, alt1Assoc)
+				}
+				if alt2Prec != 2 || alt2Assoc != assocTypeRight {
+					t.Fatalf("unexpected production precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 2, assocTypeRight, alt2Prec, alt2Assoc)
+				}
+				if alt3Prec != 3 || alt3Assoc != assocTypeNil {
+					t.Fatalf("unexpected production precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 3, assocTypeNil, alt3Prec, alt3Assoc)
+				}
+				if alt4Prec != precNil || alt4Assoc != assocTypeNil {
+					t.Fatalf("unexpected production precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", precNil, assocTypeNil, alt4Prec, alt4Assoc)
+				}
+			},
+		},
+		{
+			caption: "when a production contains no terminal symbols, the production will not have precedence and associativiry",
+			specSrc: `
+#name test;
+
+#prec (
+    #left foo
+);
+
+s
+    : a
+    ;
+a
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				var fooPrec int
+				var fooAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("foo")
+					fooPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					fooAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				var aPrec int
+				var aAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("a")
+					ps, _ := g.productionSet.findByLHS(s)
+					aPrec = g.precAndAssoc.productionPredence(ps[0].num)
+					aAssoc = g.precAndAssoc.productionAssociativity(ps[0].num)
+				}
+				var sPrec int
+				var sAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("s")
+					ps, _ := g.productionSet.findByLHS(s)
+					sPrec = g.precAndAssoc.productionPredence(ps[0].num)
+					sAssoc = g.precAndAssoc.productionAssociativity(ps[0].num)
+				}
+				if fooPrec != 1 || fooAssoc != assocTypeLeft {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 1, assocTypeLeft, fooPrec, fooAssoc)
+				}
+				if aPrec != fooPrec || aAssoc != fooAssoc {
+					t.Fatalf("unexpected production precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", fooPrec, fooAssoc, aPrec, aAssoc)
+				}
+				if sPrec != precNil || sAssoc != assocTypeNil {
+					t.Fatalf("unexpected production precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", precNil, assocTypeNil, sPrec, sAssoc)
+				}
+			},
+		},
+		{
+			caption: "the `#prec` directive applied to an alternative changes only precedence, not associativity",
+			specSrc: `
+#name test;
+
+#prec (
+    #left foo
+);
+
+s
+    : foo bar #prec foo
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				var fooPrec int
+				var fooAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("foo")
+					fooPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					fooAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				var sPrec int
+				var sAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("s")
+					ps, _ := g.productionSet.findByLHS(s)
+					sPrec = g.precAndAssoc.productionPredence(ps[0].num)
+					sAssoc = g.precAndAssoc.productionAssociativity(ps[0].num)
+				}
+				if fooPrec != 1 || fooAssoc != assocTypeLeft {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 1, assocTypeLeft, fooPrec, fooAssoc)
+				}
+				if sPrec != fooPrec || sAssoc != assocTypeNil {
+					t.Fatalf("unexpected production precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", fooPrec, assocTypeNil, sPrec, sAssoc)
+				}
+			},
+		},
+		{
+			caption: "the `#prec` directive applied to an alternative changes only precedence, not associativity",
+			specSrc: `
+#name test;
+
+#prec (
+    #left foo
+    #right bar
+);
+
+s
+    : foo bar #prec foo
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				var fooPrec int
+				var fooAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("foo")
+					fooPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					fooAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				var barPrec int
+				var barAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("bar")
+					barPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					barAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				var sPrec int
+				var sAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("s")
+					ps, _ := g.productionSet.findByLHS(s)
+					sPrec = g.precAndAssoc.productionPredence(ps[0].num)
+					sAssoc = g.precAndAssoc.productionAssociativity(ps[0].num)
+				}
+				if fooPrec != 1 || fooAssoc != assocTypeLeft {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 1, assocTypeLeft, fooPrec, fooAssoc)
+				}
+				if barPrec != 2 || barAssoc != assocTypeRight {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 2, assocTypeRight, barPrec, barAssoc)
+				}
+				if sPrec != fooPrec || sAssoc != assocTypeNil {
+					t.Fatalf("unexpected production precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", fooPrec, assocTypeNil, sPrec, sAssoc)
+				}
+			},
+		},
+		{
+			caption: "an ordered symbol can appear in a `#left` directive",
+			specSrc: `
+#name test;
+
+#prec (
+    #left $high
+    #right foo bar
+    #left $low
+);
+
+s
+    : foo #prec $high
+    | bar #prec $low
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				var fooPrec int
+				var fooAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("foo")
+					fooPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					fooAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				if fooPrec != 2 || fooAssoc != assocTypeRight {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 2, assocTypeRight, fooPrec, fooAssoc)
+				}
+				var barPrec int
+				var barAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("bar")
+					barPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					barAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				if barPrec != 2 || barAssoc != assocTypeRight {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 2, assocTypeRight, barPrec, barAssoc)
+				}
+				var alt1Prec int
+				var alt1Assoc assocType
+				var alt2Prec int
+				var alt2Assoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("s")
+					ps, _ := g.productionSet.findByLHS(s)
+					alt1Prec = g.precAndAssoc.productionPredence(ps[0].num)
+					alt1Assoc = g.precAndAssoc.productionAssociativity(ps[0].num)
+					alt2Prec = g.precAndAssoc.productionPredence(ps[1].num)
+					alt2Assoc = g.precAndAssoc.productionAssociativity(ps[1].num)
+				}
+				if alt1Prec != 1 || alt1Assoc != assocTypeNil {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 1, assocTypeNil, alt1Prec, alt1Assoc)
+				}
+				if alt2Prec != 3 || alt2Assoc != assocTypeNil {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 3, assocTypeNil, alt2Prec, alt2Assoc)
+				}
+			},
+		},
+		{
+			caption: "an ordered symbol can appear in a `#right` directive",
+			specSrc: `
+#name test;
+
+#prec (
+    #right $high
+    #left foo bar
+    #right $low
+);
+
+s
+    : foo #prec $high
+    | bar #prec $low
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				var fooPrec int
+				var fooAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("foo")
+					fooPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					fooAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				if fooPrec != 2 || fooAssoc != assocTypeLeft {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 2, assocTypeLeft, fooPrec, fooAssoc)
+				}
+				var barPrec int
+				var barAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("bar")
+					barPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					barAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				if barPrec != 2 || barAssoc != assocTypeLeft {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 2, assocTypeLeft, barPrec, barAssoc)
+				}
+				var alt1Prec int
+				var alt1Assoc assocType
+				var alt2Prec int
+				var alt2Assoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("s")
+					ps, _ := g.productionSet.findByLHS(s)
+					alt1Prec = g.precAndAssoc.productionPredence(ps[0].num)
+					alt1Assoc = g.precAndAssoc.productionAssociativity(ps[0].num)
+					alt2Prec = g.precAndAssoc.productionPredence(ps[1].num)
+					alt2Assoc = g.precAndAssoc.productionAssociativity(ps[1].num)
+				}
+				if alt1Prec != 1 || alt1Assoc != assocTypeNil {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 1, assocTypeNil, alt1Prec, alt1Assoc)
+				}
+				if alt2Prec != 3 || alt2Assoc != assocTypeNil {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 3, assocTypeNil, alt2Prec, alt2Assoc)
+				}
+			},
+		},
+		{
+			caption: "an ordered symbol can appear in a `#assign` directive",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign $high
+    #left foo
+    #right bar
+    #assign $low
+);
+
+s
+    : foo #prec $high
+    | bar #prec $low
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				var fooPrec int
+				var fooAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("foo")
+					fooPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					fooAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				if fooPrec != 2 || fooAssoc != assocTypeLeft {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 2, assocTypeLeft, fooPrec, fooAssoc)
+				}
+				var barPrec int
+				var barAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("bar")
+					barPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					barAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				if barPrec != 3 || barAssoc != assocTypeRight {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 3, assocTypeRight, barPrec, barAssoc)
+				}
+				var alt1Prec int
+				var alt1Assoc assocType
+				var alt2Prec int
+				var alt2Assoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("s")
+					ps, _ := g.productionSet.findByLHS(s)
+					alt1Prec = g.precAndAssoc.productionPredence(ps[0].num)
+					alt1Assoc = g.precAndAssoc.productionAssociativity(ps[0].num)
+					alt2Prec = g.precAndAssoc.productionPredence(ps[1].num)
+					alt2Assoc = g.precAndAssoc.productionAssociativity(ps[1].num)
+				}
+				if alt1Prec != 1 || alt1Assoc != assocTypeNil {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 1, assocTypeNil, alt1Prec, alt1Assoc)
+				}
+				if alt2Prec != 4 || alt2Assoc != assocTypeNil {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 4, assocTypeNil, alt2Prec, alt2Assoc)
+				}
+			},
+		},
+		{
+			caption: "names of an ordered symbol and a terminal symbol can duplicate",
+			specSrc: `
+#name test;
+
+#prec (
+    #left foo bar
+    #right $foo
+);
+
+s
+    : foo
+    | bar #prec $foo
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				var fooPrec int
+				var fooAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("foo")
+					fooPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					fooAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				var barPrec int
+				var barAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("bar")
+					barPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					barAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				if fooPrec != 1 || fooAssoc != assocTypeLeft {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 1, assocTypeLeft, fooPrec, fooAssoc)
+				}
+				if barPrec != 1 || barAssoc != assocTypeLeft {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 1, assocTypeLeft, barPrec, barAssoc)
+				}
+				var alt1Prec int
+				var alt1Assoc assocType
+				var alt2Prec int
+				var alt2Assoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("s")
+					ps, _ := g.productionSet.findByLHS(s)
+					alt1Prec = g.precAndAssoc.productionPredence(ps[0].num)
+					alt1Assoc = g.precAndAssoc.productionAssociativity(ps[0].num)
+					alt2Prec = g.precAndAssoc.productionPredence(ps[1].num)
+					alt2Assoc = g.precAndAssoc.productionAssociativity(ps[1].num)
+				}
+				if alt1Prec != fooPrec || alt1Assoc != fooAssoc {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", fooPrec, fooAssoc, alt1Prec, alt1Assoc)
+				}
+				if alt2Prec != 2 || alt2Assoc != assocTypeNil {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 2, assocTypeNil, alt2Prec, alt2Assoc)
+				}
+			},
+		},
+		{
+			caption: "names of an ordered symbol and a non-terminal symbol can duplicate",
+			specSrc: `
+#name test;
+
+#prec (
+    #left foo bar
+    #right $a
+);
+
+s
+    : a
+    | bar #prec $a
+    ;
+a
+    : foo
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+`,
+			validate: func(t *testing.T, g *Grammar) {
+				var barPrec int
+				var barAssoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("bar")
+					barPrec = g.precAndAssoc.terminalPrecedence(s.Num())
+					barAssoc = g.precAndAssoc.terminalAssociativity(s.Num())
+				}
+				if barPrec != 1 || barAssoc != assocTypeLeft {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 1, assocTypeLeft, barPrec, barAssoc)
+				}
+				var alt1Prec int
+				var alt1Assoc assocType
+				var alt2Prec int
+				var alt2Assoc assocType
+				{
+					s, _ := g.symbolTable.ToSymbol("s")
+					ps, _ := g.productionSet.findByLHS(s)
+					alt1Prec = g.precAndAssoc.productionPredence(ps[0].num)
+					alt1Assoc = g.precAndAssoc.productionAssociativity(ps[0].num)
+					alt2Prec = g.precAndAssoc.productionPredence(ps[1].num)
+					alt2Assoc = g.precAndAssoc.productionAssociativity(ps[1].num)
+				}
+				if alt1Prec != precNil || alt1Assoc != assocTypeNil {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", precNil, assocTypeNil, alt1Prec, alt1Assoc)
+				}
+				if alt2Prec != 2 || alt2Assoc != assocTypeNil {
+					t.Fatalf("unexpected terminal precedence and associativity: want: (prec: %v, assoc: %v), got: (prec: %v, assoc: %v)", 2, assocTypeNil, alt2Prec, alt2Assoc)
+				}
+			},
+		},
+	}
+
+	var tests []*okTest
+	tests = append(tests, nameTests...)
+	tests = append(tests, modeTests...)
+	tests = append(tests, precTests...)
+
+	for _, test := range tests {
+		t.Run(test.caption, func(t *testing.T) {
+			ast, err := parser.Parse(strings.NewReader(test.specSrc))
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			b := GrammarBuilder{
+				AST: ast,
+			}
+			g, err := b.build()
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+			if test.validate != nil {
+				test.validate(t, g)
+			}
+		})
+	}
+}
+
+func TestGrammarBuilderSpecError(t *testing.T) {
+	type specErrTest struct {
+		caption string
+		specSrc string
+		errs    []error
+	}
+
+	spellingInconsistenciesTests := []*specErrTest{
+		{
+			caption: "a spelling inconsistency appears among non-terminal symbols",
+			specSrc: `
+#name test;
+
+a1
+    : a_1
+    ;
+a_1
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrSpellingInconsistency},
+		},
+		{
+			caption: "a spelling inconsistency appears among terminal symbols",
+			specSrc: `
+#name test;
+
+s
+    : foo1 foo_1
+    ;
+
+foo1
+    : 'foo1';
+foo_1
+    : 'foo_1';
+`,
+			errs: []error{semErrSpellingInconsistency},
+		},
+		{
+			caption: "a spelling inconsistency appears among non-terminal and terminal symbols",
+			specSrc: `
+#name test;
+
+a1
+    : a_1
+    ;
+
+a_1
+    : 'a_1';
+`,
+			errs: []error{semErrSpellingInconsistency},
+		},
+		{
+			caption: "a spelling inconsistency appears among ordered symbols whose precedence is the same",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign $p1 $p_1
+);
+
+s
+    : foo #prec $p1
+    | bar #prec $p_1
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+`,
+			errs: []error{semErrSpellingInconsistency},
+		},
+		{
+			caption: "a spelling inconsistency appears among ordered symbols whose precedence is not the same",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign $p1
+    #assign $p_1
+);
+
+s
+    : foo #prec $p1
+    | bar #prec $p_1
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+`,
+			errs: []error{semErrSpellingInconsistency},
+		},
+		{
+			caption: "a spelling inconsistency appears among labels the same alternative contains",
+			specSrc: `
+#name test;
+
+s
+    : foo@l1 foo@l_1
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrSpellingInconsistency},
+		},
+		{
+			caption: "a spelling inconsistency appears among labels the same production contains",
+			specSrc: `
+#name test;
+
+s
+    : foo@l1
+    | bar@l_1
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+`,
+			errs: []error{semErrSpellingInconsistency},
+		},
+		{
+			caption: "a spelling inconsistency appears among labels different productions contain",
+			specSrc: `
+#name test;
+
+s
+    : foo@l1
+    ;
+a
+    : bar@l_1
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+`,
+			errs: []error{semErrSpellingInconsistency},
+		},
+	}
+
+	prodTests := []*specErrTest{
+		{
+			caption: "a production `b` is unused",
+			specSrc: `
+#name test;
+
+a
+    : foo
+    ;
+b
+    : foo
+    ;
+
+foo
+    : "foo";
+`,
+			errs: []error{semErrUnusedProduction},
+		},
+		{
+			caption: "a terminal symbol `bar` is unused",
+			specSrc: `
+#name test;
+
+s
+    : foo
+    ;
+
+foo
+    : "foo";
+bar
+    : "bar";
+`,
+			errs: []error{semErrUnusedTerminal},
+		},
+		{
+			caption: "a production `b` and terminal symbol `bar` is unused",
+			specSrc: `
+#name test;
+
+a
+    : foo
+    ;
+b
+    : bar
+    ;
+
+foo
+    : "foo";
+bar
+    : "bar";
+`,
+			errs: []error{
+				semErrUnusedProduction,
+				semErrUnusedTerminal,
+			},
+		},
+		{
+			caption: "a production cannot have production directives",
+			specSrc: `
+#name test;
+
+s #prec foo
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrInvalidProdDir},
+		},
+		{
+			caption: "a lexical production cannot have alternative directives",
+			specSrc: `
+#name test;
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo' #skip;
+`,
+			errs: []error{semErrInvalidAltDir},
+		},
+		{
+			caption: "a production directive must not be duplicated",
+			specSrc: `
+#name test;
+
+s
+    : foo
+    ;
+
+foo #skip #skip
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateDir},
+		},
+		{
+			caption: "an alternative directive must not be duplicated",
+			specSrc: `
+#name test;
+
+s
+    : foo bar #ast foo bar #ast foo bar
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+`,
+			errs: []error{semErrDuplicateDir},
+		},
+		{
+			caption: "a production must not have a duplicate alternative (non-empty alternatives)",
+			specSrc: `
+#name test;
+
+s
+    : foo
+    | foo
+    ;
+
+foo
+    : "foo";
+`,
+			errs: []error{semErrDuplicateProduction},
+		},
+		{
+			caption: "a production must not have a duplicate alternative (non-empty and split alternatives)",
+			specSrc: `
+#name test;
+
+s
+    : foo
+    | a
+    ;
+a
+    : bar
+    ;
+s
+    : foo
+    ;
+
+foo
+    : "foo";
+bar
+    : "bar";
+`,
+			errs: []error{semErrDuplicateProduction},
+		},
+		{
+			caption: "a production must not have a duplicate alternative (empty alternatives)",
+			specSrc: `
+#name test;
+
+s
+    : foo
+    | a
+    ;
+a
+    :
+    |
+    ;
+
+foo
+    : "foo";
+`,
+			errs: []error{semErrDuplicateProduction},
+		},
+		{
+			caption: "a production must not have a duplicate alternative (empty and split alternatives)",
+			specSrc: `
+#name test;
+
+s
+    : foo
+    | a
+    ;
+a
+    :
+    | foo
+    ;
+a
+    :
+    ;
+
+foo
+    : "foo";
+`,
+			errs: []error{semErrDuplicateProduction},
+		},
+		{
+			caption: "a terminal symbol and a non-terminal symbol (start symbol) are duplicates",
+			specSrc: `
+#name test;
+
+s
+    : foo
+    ;
+
+foo
+    : "foo";
+s
+    : "a";
+`,
+			errs: []error{semErrDuplicateName},
+		},
+		{
+			caption: "a terminal symbol and a non-terminal symbol (not start symbol) are duplicates",
+			specSrc: `
+#name test;
+
+s
+    : foo
+    | a
+    ;
+a
+    : bar
+    ;
+
+foo
+    : "foo";
+bar
+    : "bar";
+a
+    : "a";
+`,
+			errs: []error{semErrDuplicateName},
+		},
+		{
+			caption: "an invalid top-level directive",
+			specSrc: `
+#name test;
+
+#foo;
+
+s
+    : a
+    ;
+
+a
+    : 'a';
+`,
+			errs: []error{semErrDirInvalidName},
+		},
+		{
+			caption: "a label must be unique in an alternative",
+			specSrc: `
+#name test;
+
+s
+    : foo@x bar@x
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+`,
+			errs: []error{semErrDuplicateLabel},
+		},
+		{
+			caption: "a label cannot be the same name as terminal symbols",
+			specSrc: `
+#name test;
+
+s
+    : foo bar@foo
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+`,
+			errs: []error{semErrDuplicateLabel},
+		},
+		{
+			caption: "a label cannot be the same name as non-terminal symbols",
+			specSrc: `
+#name test;
+
+s
+    : foo@a
+    | a
+    ;
+a
+    : bar
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+`,
+			errs: []error{
+				semErrInvalidLabel,
+			},
+		},
+	}
+
+	nameDirTests := []*specErrTest{
+		{
+			caption: "the `#name` directive is required",
+			specSrc: `
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrNoGrammarName},
+		},
+		{
+			caption: "the `#name` directive needs an ID parameter",
+			specSrc: `
+#name;
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#name` directive cannot take a pattern parameter",
+			specSrc: `
+#name "test";
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#name` directive cannot take a string parameter",
+			specSrc: `
+#name 'test';
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#name` directive takes just one parameter",
+			specSrc: `
+#name test1 test2;
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+	}
+
+	precDirTests := []*specErrTest{
+		{
+			caption: "the `#prec` directive needs a directive group parameter",
+			specSrc: `
+#name test;
+
+#prec;
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#prec` directive cannot take an ID parameter",
+			specSrc: `
+#name test;
+
+#prec foo;
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#prec` directive cannot take an ordered symbol parameter",
+			specSrc: `
+#name test;
+
+#prec $x;
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#prec` directive cannot take a pattern parameter",
+			specSrc: `
+#name test;
+
+#prec "foo";
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#prec` directive cannot take a string parameter",
+			specSrc: `
+#name test;
+
+#prec 'foo';
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#prec` directive takes just one directive group parameter",
+			specSrc: `
+#name test;
+
+#prec () ();
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+	}
+
+	leftDirTests := []*specErrTest{
+		{
+			caption: "the `#left` directive needs ID parameters",
+			specSrc: `
+#name test;
+
+#prec (
+    #left
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#left` directive cannot be applied to an error symbol",
+			specSrc: `
+#name test;
+
+#prec (
+    #left error
+);
+
+s
+    : foo semi_colon
+    | error semi_colon
+    ;
+
+foo
+    : 'foo';
+semi_colon
+    : ';';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#left` directive cannot take an undefined symbol",
+			specSrc: `
+#name test;
+
+#prec (
+    #left x
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#left` directive cannot take a non-terminal symbol",
+			specSrc: `
+#name test;
+
+#prec (
+    #left s
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#left` directive cannot take a pattern parameter",
+			specSrc: `
+#name test;
+
+#prec (
+    #left "foo"
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#left` directive cannot take a string parameter",
+			specSrc: `
+#name test;
+
+#prec (
+    #left 'foo'
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#left` directive cannot take a directive parameter",
+			specSrc: `
+#name test;
+
+#prec (
+    #left ()
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#left` dirctive cannot be specified multiple times for a terminal symbol",
+			specSrc: `
+#name test;
+
+#prec (
+    #left foo foo
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateAssoc},
+		},
+		{
+			caption: "the `#left` dirctive cannot be specified multiple times for an ordered symbol",
+			specSrc: `
+#name test;
+
+#prec (
+    #left $x $x
+);
+
+s
+    : foo #prec $x
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateAssoc},
+		},
+		{
+			caption: "a terminal symbol cannot have different precedence",
+			specSrc: `
+#name test;
+
+#prec (
+    #left foo
+    #left foo
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateAssoc},
+		},
+		{
+			caption: "an ordered symbol cannot have different precedence",
+			specSrc: `
+#name test;
+
+#prec (
+    #left $x
+    #left $x
+);
+
+s
+    : foo #prec $x
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateAssoc},
+		},
+		{
+			caption: "a terminal symbol cannot have different associativity",
+			specSrc: `
+#name test;
+
+#prec (
+    #right foo
+    #left foo
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateAssoc},
+		},
+		{
+			caption: "an ordered symbol cannot have different associativity",
+			specSrc: `
+#name test;
+
+#prec (
+    #right $x
+    #left $x
+);
+
+s
+    : foo #prec $x
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateAssoc},
+		},
+	}
+
+	rightDirTests := []*specErrTest{
+		{
+			caption: "the `#right` directive needs ID parameters",
+			specSrc: `
+#name test;
+
+#prec (
+    #right
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#right` directive cannot be applied to an error symbol",
+			specSrc: `
+#name test;
+
+#prec (
+    #right error
+);
+
+s
+    : foo semi_colon
+    | error semi_colon
+    ;
+
+foo
+    : 'foo';
+semi_colon
+    : ';';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#right` directive cannot take an undefined symbol",
+			specSrc: `
+#name test;
+
+#prec (
+    #right x
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#right` directive cannot take a non-terminal symbol",
+			specSrc: `
+#name test;
+
+#prec (
+    #right s
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#right` directive cannot take a pattern parameter",
+			specSrc: `
+#name test;
+
+#prec (
+    #right "foo"
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#right` directive cannot take a string parameter",
+			specSrc: `
+#name test;
+
+#prec (
+    #right 'foo'
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#right` directive cannot take a directive group parameter",
+			specSrc: `
+#name test;
+
+#prec (
+    #right ()
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#right` directive cannot be specified multiple times for a terminal symbol",
+			specSrc: `
+#name test;
+
+#prec (
+    #right foo foo
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateAssoc},
+		},
+		{
+			caption: "the `#right` directive cannot be specified multiple times for an ordered symbol",
+			specSrc: `
+#name test;
+
+#prec (
+    #right $x $x
+);
+
+s
+    : foo #prec $x
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateAssoc},
+		},
+		{
+			caption: "a terminal symbol cannot have different precedence",
+			specSrc: `
+#name test;
+
+#prec (
+    #right foo
+    #right foo
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateAssoc},
+		},
+		{
+			caption: "an ordered symbol cannot have different precedence",
+			specSrc: `
+#name test;
+
+#prec (
+    #right $x
+    #right $x
+);
+
+s
+    : foo #prec $x
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateAssoc},
+		},
+		{
+			caption: "a terminal symbol cannot have different associativity",
+			specSrc: `
+#name test;
+
+#prec (
+    #left foo
+    #right foo
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateAssoc},
+		},
+		{
+			caption: "an ordered symbol cannot have different associativity",
+			specSrc: `
+#name test;
+
+#prec (
+    #left $x
+    #right $x
+);
+
+s
+    : foo #prec $x
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateAssoc},
+		},
+	}
+
+	assignDirTests := []*specErrTest{
+		{
+			caption: "the `#assign` directive needs ID parameters",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#assign` directive cannot be applied to an error symbol",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign error
+);
+
+s
+    : foo semi_colon
+    | error semi_colon
+    ;
+
+foo
+    : 'foo';
+semi_colon
+    : ';';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#assign` directive cannot take an undefined symbol",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign x
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#assign` directive cannot take a non-terminal symbol",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign s
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#assign` directive cannot take a pattern parameter",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign "foo"
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#assign` directive cannot take a string parameter",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign 'foo'
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#assign` directive cannot take a directive parameter",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign ()
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#assign` dirctive cannot be specified multiple times for a terminal symbol",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign foo foo
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateAssoc},
+		},
+		{
+			caption: "the `#assign` dirctive cannot be specified multiple times for an ordered symbol",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign $x $x
+);
+
+s
+    : foo #prec $x
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateAssoc},
+		},
+		{
+			caption: "a terminal symbol cannot have different precedence",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign foo
+    #assign foo
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateAssoc},
+		},
+		{
+			caption: "an ordered symbol cannot have different precedence",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign $x
+    #assign $x
+);
+
+s
+    : foo #prec $x
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateAssoc},
+		},
+		{
+			caption: "a terminal symbol cannot have different associativity",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign foo
+    #left foo
+);
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateAssoc},
+		},
+		{
+			caption: "an ordered symbol cannot have different associativity",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign $x
+    #left $x
+);
+
+s
+    : foo #prec $x
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateAssoc},
+		},
+	}
+
+	errorSymTests := []*specErrTest{
+		{
+			caption: "cannot use the error symbol as a non-terminal symbol",
+			specSrc: `
+#name test;
+
+s
+    : error
+    ;
+error
+    : foo
+    ;
+
+foo: 'foo';
+`,
+			errs: []error{
+				semErrErrSymIsReserved,
+				semErrDuplicateName,
+			},
+		},
+		{
+			caption: "cannot use the error symbol as a terminal symbol",
+			specSrc: `
+#name test;
+
+s
+    : error
+    ;
+
+error: 'error';
+`,
+			errs: []error{semErrErrSymIsReserved},
+		},
+		{
+			caption: "cannot use the error symbol as a terminal symbol, even if given the skip directive",
+			specSrc: `
+#name test;
+
+s
+    : foo
+    ;
+
+foo
+    : 'foo';
+error #skip
+    : 'error';
+`,
+			errs: []error{semErrErrSymIsReserved},
+		},
+	}
+
+	astDirTests := []*specErrTest{
+		{
+			caption: "the `#ast` directive needs ID or label prameters",
+			specSrc: `
+#name test;
+
+s
+    : foo #ast
+    ;
+
+foo
+    : "foo";
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#ast` directive cannot take an ordered symbol parameter",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign $x
+);
+
+s
+    : foo #ast $x
+    ;
+
+foo
+    : "foo";
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#ast` directive cannot take a pattern parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo #ast "foo"
+    ;
+
+foo
+    : "foo";
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#ast` directive cannot take a string parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo #ast 'foo'
+    ;
+
+foo
+    : "foo";
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#ast` directive cannot take a directive group parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo #ast ()
+    ;
+
+foo
+    : "foo";
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "a parameter of the `#ast` directive must be either a symbol or a label in an alternative",
+			specSrc: `
+#name test;
+
+s
+    : foo bar #ast foo x
+    ;
+
+foo
+    : "foo";
+bar
+    : "bar";
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "a symbol in a different alternative cannot be a parameter of the `#ast` directive",
+			specSrc: `
+#name test;
+
+s
+    : foo #ast bar
+    | bar
+    ;
+
+foo
+    : "foo";
+bar
+    : "bar";
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "a label in a different alternative cannot be a parameter of the `#ast` directive",
+			specSrc: `
+#name test;
+
+s
+    : foo #ast b
+    | bar@b
+    ;
+
+foo
+    : "foo";
+bar
+    : "bar";
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "a symbol can appear in the `#ast` directive only once",
+			specSrc: `
+#name test;
+
+s
+    : foo #ast foo foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateElem},
+		},
+		{
+			caption: "a label can appear in the `#ast` directive only once",
+			specSrc: `
+#name test;
+
+s
+    : foo@x #ast x x
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateElem},
+		},
+		{
+			caption: "a symbol can appear in the `#ast` directive only once, even if the symbol has a label",
+			specSrc: `
+#name test;
+
+s
+    : foo@x #ast foo x
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDuplicateElem},
+		},
+		{
+			caption: "symbol `foo` is ambiguous because it appears in an alternative twice",
+			specSrc: `
+#name test;
+
+s
+    : foo foo #ast foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrAmbiguousElem},
+		},
+		{
+			caption: "symbol `foo` is ambiguous because it appears in an alternative twice, even if one of them has a label",
+			specSrc: `
+#name test;
+
+s
+    : foo@x foo #ast foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrAmbiguousElem},
+		},
+		{
+			caption: "the expansion operator cannot be applied to a terminal symbol",
+			specSrc: `
+#name test;
+
+s
+    : foo #ast foo...
+    ;
+
+foo
+    : "foo";
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+	}
+
+	altPrecDirTests := []*specErrTest{
+		{
+			caption: "the `#prec` directive needs an ID parameter or an ordered symbol parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo #prec
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#prec` directive cannot be applied to an error symbol",
+			specSrc: `
+#name test;
+
+s
+    : foo #prec error
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#prec` directive cannot take an undefined symbol",
+			specSrc: `
+#name test;
+
+s
+    : foo #prec x
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#prec` directive cannot take a non-terminal symbol",
+			specSrc: `
+#name test;
+
+s
+    : a #prec b
+    | b
+    ;
+a
+    : foo
+    ;
+b
+    : bar
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#prec` directive cannot take an undefined ordered symbol parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo #prec $x
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrUndefinedOrdSym},
+		},
+		{
+			caption: "the `#prec` directive cannot take a pattern parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo #prec "foo"
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#prec` directive cannot take a string parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo #prec 'foo'
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#prec` directive cannot take a directive parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo #prec ()
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "a symbol the `#prec` directive takes must be given precedence explicitly",
+			specSrc: `
+#name test;
+
+s
+    : foo bar #prec foo
+    ;
+
+foo
+    : 'foo';
+bar
+    : 'bar';
+`,
+			errs: []error{semErrUndefinedPrec},
+		},
+	}
+
+	recoverDirTests := []*specErrTest{
+		{
+			caption: "the `#recover` directive cannot take an ID parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo #recover foo
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#recover` directive cannot take an ordered symbol parameter",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign $x
+);
+
+s
+    : foo #recover $x
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#recover` directive cannot take a pattern parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo #recover "foo"
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#recover` directive cannot take a string parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo #recover 'foo'
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#recover` directive cannot take a directive group parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo #recover ()
+    ;
+
+foo
+    : 'foo';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+	}
+
+	fragmentTests := []*specErrTest{
+		{
+			caption: "a production cannot contain a fragment",
+			specSrc: `
+#name test;
+
+s
+    : f
+    ;
+
+fragment f
+    : 'fragment';
+`,
+			errs: []error{semErrUndefinedSym},
+		},
+		{
+			caption: "fragments cannot be duplicated",
+			specSrc: `
+#name test;
+
+s
+    : foo
+    ;
+
+foo
+    : "\f{f}";
+fragment f
+    : 'fragment 1';
+fragment f
+    : 'fragment 2';
+`,
+			errs: []error{semErrDuplicateFragment},
+		},
+	}
+
+	modeDirTests := []*specErrTest{
+		{
+			caption: "the `#mode` directive needs an ID parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo bar
+    ;
+
+foo #push mode_1
+    : 'foo';
+bar #mode
+    : 'bar';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#mode` directive cannot take an ordered symbol parameter",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign $x
+);
+
+s
+    : foo bar
+    ;
+
+foo
+    : 'foo';
+bar #mode $x
+    : 'bar';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#mode` directive cannot take a pattern parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo bar
+    ;
+
+foo #push mode_1
+    : 'foo';
+bar #mode "mode_1"
+    : 'bar';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#mode` directive cannot take a string parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo bar
+    ;
+
+foo #push mode_1
+    : 'foo';
+bar #mode 'mode_1'
+    : 'bar';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#mode` directive cannot take a directive group parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo bar
+    ;
+
+foo #push mode_1
+    : 'foo';
+bar #mode ()
+    : 'bar';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+	}
+
+	pushDirTests := []*specErrTest{
+		{
+			caption: "the `#push` directive needs an ID parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo bar
+    ;
+
+foo #push
+    : 'foo';
+bar #mode mode_1
+    : 'bar';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#push` directive takes just one ID parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo bar
+    ;
+
+foo #push mode_1 mode_2
+    : 'foo';
+bar #mode mode_1
+    : 'bar';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#push` directive cannot take an ordered symbol parameter",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign $x
+);
+
+s
+    : foo bar
+    ;
+
+foo #push $x
+    : 'foo';
+bar
+    : 'bar';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#push` directive cannot take a pattern parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo bar
+    ;
+
+foo #push "mode_1"
+    : 'foo';
+bar #mode mode_1
+    : 'bar';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#push` directive cannot take a string parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo bar
+    ;
+
+foo #push 'mode_1'
+    : 'foo';
+bar #mode mode_1
+    : 'bar';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#push` directive cannot take a directive group parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo bar
+    ;
+
+foo #push ()
+    : 'foo';
+bar #mode mode_1
+    : 'bar';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+	}
+
+	popDirTests := []*specErrTest{
+		{
+			caption: "the `#pop` directive cannot take an ID parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo bar baz
+    ;
+
+foo #push mode_1
+    : 'foo';
+bar #mode mode_1
+    : 'bar';
+baz #pop mode_1
+    : 'baz';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#pop` directive cannot take an ordered symbol parameter",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign $x
+);
+
+s
+    : foo bar baz
+    ;
+
+foo #push mode_1
+    : 'foo';
+bar #mode mode_1
+    : 'bar';
+baz #pop $x
+    : 'baz';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#pop` directive cannot take a pattern parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo bar baz
+    ;
+
+foo #push mode_1
+    : 'foo';
+bar #mode mode_1
+    : 'bar';
+baz #pop "mode_1"
+    : 'baz';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#pop` directive cannot take a string parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo bar baz
+    ;
+
+foo #push mode_1
+    : 'foo';
+bar #mode mode_1
+    : 'bar';
+baz #pop 'mode_1'
+    : 'baz';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#pop` directive cannot take a directive parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo bar baz
+    ;
+
+foo #push mode_1
+    : 'foo';
+bar #mode mode_1
+    : 'bar';
+baz #pop ()
+    : 'baz';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+	}
+
+	skipDirTests := []*specErrTest{
+		{
+			caption: "the `#skip` directive cannot take an ID parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo bar
+    ;
+
+foo #skip bar
+    : 'foo';
+bar
+    : 'bar';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#skip` directive cannot take an ordered symbol parameter",
+			specSrc: `
+#name test;
+
+#prec (
+    #assign $x
+);
+
+s
+    : foo bar
+    ;
+
+foo #skip $x
+    : 'foo';
+bar
+    : 'bar';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#skip` directive cannot take a pattern parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo bar
+    ;
+
+foo #skip "bar"
+    : 'foo';
+bar
+    : 'bar';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#skip` directive cannot take a string parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo bar
+    ;
+
+foo #skip 'bar'
+    : 'foo';
+bar
+    : 'bar';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "the `#skip` directive cannot take a directive group parameter",
+			specSrc: `
+#name test;
+
+s
+    : foo bar
+    ;
+
+foo #skip ()
+    : 'foo';
+bar
+    : 'bar';
+`,
+			errs: []error{semErrDirInvalidParam},
+		},
+		{
+			caption: "a terminal symbol used in productions cannot have the skip directive",
+			specSrc: `
+#name test;
+
+s
+    : foo bar
+    ;
+
+foo #skip
+    : 'foo';
+bar
+    : 'bar';
+`,
+			errs: []error{semErrTermCannotBeSkipped},
+		},
+	}
+
+	var tests []*specErrTest
+	tests = append(tests, spellingInconsistenciesTests...)
+	tests = append(tests, prodTests...)
+	tests = append(tests, nameDirTests...)
+	tests = append(tests, precDirTests...)
+	tests = append(tests, leftDirTests...)
+	tests = append(tests, rightDirTests...)
+	tests = append(tests, assignDirTests...)
+	tests = append(tests, errorSymTests...)
+	tests = append(tests, astDirTests...)
+	tests = append(tests, altPrecDirTests...)
+	tests = append(tests, recoverDirTests...)
+	tests = append(tests, fragmentTests...)
+	tests = append(tests, modeDirTests...)
+	tests = append(tests, pushDirTests...)
+	tests = append(tests, popDirTests...)
+	tests = append(tests, skipDirTests...)
+	for _, test := range tests {
+		t.Run(test.caption, func(t *testing.T) {
+			ast, err := parser.Parse(strings.NewReader(test.specSrc))
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			b := GrammarBuilder{
+				AST: ast,
+			}
+			_, err = b.build()
+			if err == nil {
+				t.Fatal("an expected error didn't occur")
+			}
+			specErrs, ok := err.(verr.SpecErrors)
+			if !ok {
+				t.Fatalf("unexpected error type: want: %T, got: %T: %v", verr.SpecErrors{}, err, err)
+			}
+			if len(specErrs) != len(test.errs) {
+				t.Fatalf("unexpected spec error count: want: %+v, got: %+v", test.errs, specErrs)
+			}
+			for _, expected := range test.errs {
+				for _, actual := range specErrs {
+					if actual.Cause == expected {
+						return
+					}
+				}
+			}
+			t.Fatalf("an expected spec error didn't occur: want: %v, got: %+v", test.errs, specErrs)
+		})
+	}
+}
+
+func TestGenLALR1Automaton(t *testing.T) {
+	// This grammar belongs to LALR(1) class, not SLR(1).
+	src := `
+#name test;
+
+s: l eq r | r;
+l: ref r | id;
+r: l;
+eq: '=';
+ref: '*';
+id: "[A-Za-z0-9_]+";
+`
+
+	var gram *Grammar
+	var automaton *lalr1Automaton
+	{
+		ast, err := parser.Parse(strings.NewReader(src))
+		if err != nil {
+			t.Fatal(err)
+		}
+		b := GrammarBuilder{
+			AST: ast,
+		}
+		gram, err = b.build()
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		lr0, err := genLR0Automaton(gram.productionSet, gram.augmentedStartSymbol, gram.errorSymbol)
+		if err != nil {
+			t.Fatalf("failed to create a LR0 automaton: %v", err)
+		}
+
+		firstSet, err := genFirstSet(gram.productionSet)
+		if err != nil {
+			t.Fatalf("failed to create a FIRST set: %v", err)
+		}
+
+		automaton, err = genLALR1Automaton(lr0, gram.productionSet, firstSet)
+		if err != nil {
+			t.Fatalf("failed to create a LALR1 automaton: %v", err)
+		}
+		if automaton == nil {
+			t.Fatalf("genLALR1Automaton returns nil without any error")
+		}
+	}
+
+	initialState := automaton.states[automaton.initialState]
+	if initialState == nil {
+		t.Errorf("failed to get an initial status: %v", automaton.initialState)
+	}
+
+	genSym := newTestSymbolGenerator(t, gram.symbolTable)
+	genProd := newTestProductionGenerator(t, genSym)
+	genLR0Item := newTestLR0ItemGenerator(t, genProd)
+
+	expectedKernels := map[int][]*lrItem{
+		0: {
+			withLookAhead(genLR0Item("s'", 0, "s"), symbol.SymbolEOF),
+		},
+		1: {
+			withLookAhead(genLR0Item("s'", 1, "s"), symbol.SymbolEOF),
+		},
+		2: {
+			withLookAhead(genLR0Item("s", 1, "l", "eq", "r"), symbol.SymbolEOF),
+			withLookAhead(genLR0Item("r", 1, "l"), symbol.SymbolEOF),
+		},
+		3: {
+			withLookAhead(genLR0Item("s", 1, "r"), symbol.SymbolEOF),
+		},
+		4: {
+			withLookAhead(genLR0Item("l", 1, "ref", "r"), genSym("eq"), symbol.SymbolEOF),
+		},
+		5: {
+			withLookAhead(genLR0Item("l", 1, "id"), genSym("eq"), symbol.SymbolEOF),
+		},
+		6: {
+			withLookAhead(genLR0Item("s", 2, "l", "eq", "r"), symbol.SymbolEOF),
+		},
+		7: {
+			withLookAhead(genLR0Item("l", 2, "ref", "r"), genSym("eq"), symbol.SymbolEOF),
+		},
+		8: {
+			withLookAhead(genLR0Item("r", 1, "l"), genSym("eq"), symbol.SymbolEOF),
+		},
+		9: {
+			withLookAhead(genLR0Item("s", 3, "l", "eq", "r"), symbol.SymbolEOF),
+		},
+	}
+
+	expectedStates := []*expectedLRState{
+		{
+			kernelItems: expectedKernels[0],
+			nextStates: map[symbol.Symbol][]*lrItem{
+				genSym("s"):   expectedKernels[1],
+				genSym("l"):   expectedKernels[2],
+				genSym("r"):   expectedKernels[3],
+				genSym("ref"): expectedKernels[4],
+				genSym("id"):  expectedKernels[5],
+			},
+			reducibleProds: []*production{},
+		},
+		{
+			kernelItems: expectedKernels[1],
+			nextStates:  map[symbol.Symbol][]*lrItem{},
+			reducibleProds: []*production{
+				genProd("s'", "s"),
+			},
+		},
+		{
+			kernelItems: expectedKernels[2],
+			nextStates: map[symbol.Symbol][]*lrItem{
+				genSym("eq"): expectedKernels[6],
+			},
+			reducibleProds: []*production{
+				genProd("r", "l"),
+			},
+		},
+		{
+			kernelItems: expectedKernels[3],
+			nextStates:  map[symbol.Symbol][]*lrItem{},
+			reducibleProds: []*production{
+				genProd("s", "r"),
+			},
+		},
+		{
+			kernelItems: expectedKernels[4],
+			nextStates: map[symbol.Symbol][]*lrItem{
+				genSym("r"):   expectedKernels[7],
+				genSym("l"):   expectedKernels[8],
+				genSym("ref"): expectedKernels[4],
+				genSym("id"):  expectedKernels[5],
+			},
+			reducibleProds: []*production{},
+		},
+		{
+			kernelItems: expectedKernels[5],
+			nextStates:  map[symbol.Symbol][]*lrItem{},
+			reducibleProds: []*production{
+				genProd("l", "id"),
+			},
+		},
+		{
+			kernelItems: expectedKernels[6],
+			nextStates: map[symbol.Symbol][]*lrItem{
+				genSym("r"):   expectedKernels[9],
+				genSym("l"):   expectedKernels[8],
+				genSym("ref"): expectedKernels[4],
+				genSym("id"):  expectedKernels[5],
+			},
+			reducibleProds: []*production{},
+		},
+		{
+			kernelItems: expectedKernels[7],
+			nextStates:  map[symbol.Symbol][]*lrItem{},
+			reducibleProds: []*production{
+				genProd("l", "ref", "r"),
+			},
+		},
+		{
+			kernelItems: expectedKernels[8],
+			nextStates:  map[symbol.Symbol][]*lrItem{},
+			reducibleProds: []*production{
+				genProd("r", "l"),
+			},
+		},
+		{
+			kernelItems: expectedKernels[9],
+			nextStates:  map[symbol.Symbol][]*lrItem{},
+			reducibleProds: []*production{
+				genProd("s", "l", "eq", "r"),
+			},
+		},
+	}
+
+	testLRAutomaton(t, expectedStates, automaton.lr0Automaton)
+}
+
+type expectedLRState struct {
+	kernelItems    []*lrItem
+	nextStates     map[symbol.Symbol][]*lrItem
+	reducibleProds []*production
+	emptyProdItems []*lrItem
+}
+
+func TestGenLR0Automaton(t *testing.T) {
+	src := `
+#name test;
+
+expr
+    : expr add term
+    | term
+    ;
+term
+    : term mul factor
+    | factor
+    ;
+factor
+    : l_paren expr r_paren
+    | id
+    ;
+add: "\+";
+mul: "\*";
+l_paren: "\(";
+r_paren: "\)";
+id: "[A-Za-z_][0-9A-Za-z_]*";
+`
+
+	var gram *Grammar
+	var automaton *lr0Automaton
+	{
+		ast, err := parser.Parse(strings.NewReader(src))
+		if err != nil {
+			t.Fatal(err)
+		}
+		b := GrammarBuilder{
+			AST: ast,
+		}
+		gram, err = b.build()
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		automaton, err = genLR0Automaton(gram.productionSet, gram.augmentedStartSymbol, gram.errorSymbol)
+		if err != nil {
+			t.Fatalf("failed to create a LR0 automaton: %v", err)
+		}
+		if automaton == nil {
+			t.Fatalf("genLR0Automaton returns nil without any error")
+		}
+	}
+
+	initialState := automaton.states[automaton.initialState]
+	if initialState == nil {
+		t.Errorf("failed to get an initial status: %v", automaton.initialState)
+	}
+
+	genSym := newTestSymbolGenerator(t, gram.symbolTable)
+	genProd := newTestProductionGenerator(t, genSym)
+	genLR0Item := newTestLR0ItemGenerator(t, genProd)
+
+	expectedKernels := map[int][]*lrItem{
+		0: {
+			genLR0Item("expr'", 0, "expr"),
+		},
+		1: {
+			genLR0Item("expr'", 1, "expr"),
+			genLR0Item("expr", 1, "expr", "add", "term"),
+		},
+		2: {
+			genLR0Item("expr", 1, "term"),
+			genLR0Item("term", 1, "term", "mul", "factor"),
+		},
+		3: {
+			genLR0Item("term", 1, "factor"),
+		},
+		4: {
+			genLR0Item("factor", 1, "l_paren", "expr", "r_paren"),
+		},
+		5: {
+			genLR0Item("factor", 1, "id"),
+		},
+		6: {
+			genLR0Item("expr", 2, "expr", "add", "term"),
+		},
+		7: {
+			genLR0Item("term", 2, "term", "mul", "factor"),
+		},
+		8: {
+			genLR0Item("expr", 1, "expr", "add", "term"),
+			genLR0Item("factor", 2, "l_paren", "expr", "r_paren"),
+		},
+		9: {
+			genLR0Item("expr", 3, "expr", "add", "term"),
+			genLR0Item("term", 1, "term", "mul", "factor"),
+		},
+		10: {
+			genLR0Item("term", 3, "term", "mul", "factor"),
+		},
+		11: {
+			genLR0Item("factor", 3, "l_paren", "expr", "r_paren"),
+		},
+	}
+
+	expectedStates := []*expectedLRState{
+		{
+			kernelItems: expectedKernels[0],
+			nextStates: map[symbol.Symbol][]*lrItem{
+				genSym("expr"):    expectedKernels[1],
+				genSym("term"):    expectedKernels[2],
+				genSym("factor"):  expectedKernels[3],
+				genSym("l_paren"): expectedKernels[4],
+				genSym("id"):      expectedKernels[5],
+			},
+			reducibleProds: []*production{},
+		},
+		{
+			kernelItems: expectedKernels[1],
+			nextStates: map[symbol.Symbol][]*lrItem{
+				genSym("add"): expectedKernels[6],
+			},
+			reducibleProds: []*production{
+				genProd("expr'", "expr"),
+			},
+		},
+		{
+			kernelItems: expectedKernels[2],
+			nextStates: map[symbol.Symbol][]*lrItem{
+				genSym("mul"): expectedKernels[7],
+			},
+			reducibleProds: []*production{
+				genProd("expr", "term"),
+			},
+		},
+		{
+			kernelItems: expectedKernels[3],
+			nextStates:  map[symbol.Symbol][]*lrItem{},
+			reducibleProds: []*production{
+				genProd("term", "factor"),
+			},
+		},
+		{
+			kernelItems: expectedKernels[4],
+			nextStates: map[symbol.Symbol][]*lrItem{
+				genSym("expr"):    expectedKernels[8],
+				genSym("term"):    expectedKernels[2],
+				genSym("factor"):  expectedKernels[3],
+				genSym("l_paren"): expectedKernels[4],
+				genSym("id"):      expectedKernels[5],
+			},
+			reducibleProds: []*production{},
+		},
+		{
+			kernelItems: expectedKernels[5],
+			nextStates:  map[symbol.Symbol][]*lrItem{},
+			reducibleProds: []*production{
+				genProd("factor", "id"),
+			},
+		},
+		{
+			kernelItems: expectedKernels[6],
+			nextStates: map[symbol.Symbol][]*lrItem{
+				genSym("term"):    expectedKernels[9],
+				genSym("factor"):  expectedKernels[3],
+				genSym("l_paren"): expectedKernels[4],
+				genSym("id"):      expectedKernels[5],
+			},
+			reducibleProds: []*production{},
+		},
+		{
+			kernelItems: expectedKernels[7],
+			nextStates: map[symbol.Symbol][]*lrItem{
+				genSym("factor"):  expectedKernels[10],
+				genSym("l_paren"): expectedKernels[4],
+				genSym("id"):      expectedKernels[5],
+			},
+			reducibleProds: []*production{},
+		},
+		{
+			kernelItems: expectedKernels[8],
+			nextStates: map[symbol.Symbol][]*lrItem{
+				genSym("add"):     expectedKernels[6],
+				genSym("r_paren"): expectedKernels[11],
+			},
+			reducibleProds: []*production{},
+		},
+		{
+			kernelItems: expectedKernels[9],
+			nextStates: map[symbol.Symbol][]*lrItem{
+				genSym("mul"): expectedKernels[7],
+			},
+			reducibleProds: []*production{
+				genProd("expr", "expr", "add", "term"),
+			},
+		},
+		{
+			kernelItems: expectedKernels[10],
+			nextStates:  map[symbol.Symbol][]*lrItem{},
+			reducibleProds: []*production{
+				genProd("term", "term", "mul", "factor"),
+			},
+		},
+		{
+			kernelItems: expectedKernels[11],
+			nextStates:  map[symbol.Symbol][]*lrItem{},
+			reducibleProds: []*production{
+				genProd("factor", "l_paren", "expr", "r_paren"),
+			},
+		},
+	}
+
+	testLRAutomaton(t, expectedStates, automaton)
+}
+
+func TestLR0AutomatonContainingEmptyProduction(t *testing.T) {
+	src := `
+#name test;
+
+s
+    : foo bar
+    ;
+foo
+    :
+    ;
+bar
+    : b
+    |
+    ;
+
+b: "bar";
+`
+
+	var gram *Grammar
+	var automaton *lr0Automaton
+	{
+		ast, err := parser.Parse(strings.NewReader(src))
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		b := GrammarBuilder{
+			AST: ast,
+		}
+		gram, err = b.build()
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		automaton, err = genLR0Automaton(gram.productionSet, gram.augmentedStartSymbol, gram.errorSymbol)
+		if err != nil {
+			t.Fatalf("failed to create a LR0 automaton: %v", err)
+		}
+		if automaton == nil {
+			t.Fatalf("genLR0Automaton returns nil without any error")
+		}
+	}
+
+	initialState := automaton.states[automaton.initialState]
+	if initialState == nil {
+		t.Errorf("failed to get an initial status: %v", automaton.initialState)
+	}
+
+	genSym := newTestSymbolGenerator(t, gram.symbolTable)
+	genProd := newTestProductionGenerator(t, genSym)
+	genLR0Item := newTestLR0ItemGenerator(t, genProd)
+
+	expectedKernels := map[int][]*lrItem{
+		0: {
+			genLR0Item("s'", 0, "s"),
+		},
+		1: {
+			genLR0Item("s'", 1, "s"),
+		},
+		2: {
+			genLR0Item("s", 1, "foo", "bar"),
+		},
+		3: {
+			genLR0Item("s", 2, "foo", "bar"),
+		},
+		4: {
+			genLR0Item("bar", 1, "b"),
+		},
+	}
+
+	expectedStates := []*expectedLRState{
+		{
+			kernelItems: expectedKernels[0],
+			nextStates: map[symbol.Symbol][]*lrItem{
+				genSym("s"):   expectedKernels[1],
+				genSym("foo"): expectedKernels[2],
+			},
+			reducibleProds: []*production{
+				genProd("foo"),
+			},
+			emptyProdItems: []*lrItem{
+				genLR0Item("foo", 0),
+			},
+		},
+		{
+			kernelItems: expectedKernels[1],
+			nextStates:  map[symbol.Symbol][]*lrItem{},
+			reducibleProds: []*production{
+				genProd("s'", "s"),
+			},
+		},
+		{
+			kernelItems: expectedKernels[2],
+			nextStates: map[symbol.Symbol][]*lrItem{
+				genSym("bar"): expectedKernels[3],
+				genSym("b"):   expectedKernels[4],
+			},
+			reducibleProds: []*production{
+				genProd("bar"),
+			},
+			emptyProdItems: []*lrItem{
+				genLR0Item("bar", 0),
+			},
+		},
+		{
+			kernelItems: expectedKernels[3],
+			nextStates:  map[symbol.Symbol][]*lrItem{},
+			reducibleProds: []*production{
+				genProd("s", "foo", "bar"),
+			},
+		},
+		{
+			kernelItems: expectedKernels[4],
+			nextStates:  map[symbol.Symbol][]*lrItem{},
+			reducibleProds: []*production{
+				genProd("bar", "b"),
+			},
+		},
+	}
+
+	testLRAutomaton(t, expectedStates, automaton)
+}
+
+func testLRAutomaton(t *testing.T, expected []*expectedLRState, automaton *lr0Automaton) {
+	if len(automaton.states) != len(expected) {
+		t.Errorf("state count is mismatched; want: %v, got: %v", len(expected), len(automaton.states))
+	}
+
+	for i, eState := range expected {
+		t.Run(fmt.Sprintf("state #%v", i), func(t *testing.T) {
+			k, err := newKernel(eState.kernelItems)
+			if err != nil {
+				t.Fatalf("failed to create a kernel item: %v", err)
+			}
+
+			state, ok := automaton.states[k.id]
+			if !ok {
+				t.Fatalf("a kernel was not found: %v", k.id)
+			}
+
+			// test look-ahead symbols
+			{
+				if len(state.kernel.items) != len(eState.kernelItems) {
+					t.Errorf("kernels is mismatched; want: %v, got: %v", len(eState.kernelItems), len(state.kernel.items))
+				}
+				for _, eKItem := range eState.kernelItems {
+					var kItem *lrItem
+					for _, it := range state.kernel.items {
+						if it.id != eKItem.id {
+							continue
+						}
+						kItem = it
+						break
+					}
+					if kItem == nil {
+						t.Fatalf("kernel item not found; want: %v, got: %v", eKItem.id, kItem.id)
+					}
+
+					if len(kItem.lookAhead.symbols) != len(eKItem.lookAhead.symbols) {
+						t.Errorf("look-ahead symbols are mismatched; want: %v symbols, got: %v symbols", len(eKItem.lookAhead.symbols), len(kItem.lookAhead.symbols))
+					}
+
+					for eSym := range eKItem.lookAhead.symbols {
+						if _, ok := kItem.lookAhead.symbols[eSym]; !ok {
+							t.Errorf("look-ahead symbol not found: %v", eSym)
+						}
+					}
+				}
+			}
+
+			// test next states
+			{
+				if len(state.next) != len(eState.nextStates) {
+					t.Errorf("next state count is mismcthed; want: %v, got: %v", len(eState.nextStates), len(state.next))
+				}
+				for eSym, eKItems := range eState.nextStates {
+					nextStateKernel, err := newKernel(eKItems)
+					if err != nil {
+						t.Fatalf("failed to create a kernel item: %v", err)
+					}
+					nextState, ok := state.next[eSym]
+					if !ok {
+						t.Fatalf("next state was not found; state: %v, symbol: %v (%v)", state.id, "expr", eSym)
+					}
+					if nextState != nextStateKernel.id {
+						t.Fatalf("a kernel ID of the next state is mismatched; want: %v, got: %v", nextStateKernel.id, nextState)
+					}
+				}
+			}
+
+			// test reducible productions
+			{
+				if len(state.reducible) != len(eState.reducibleProds) {
+					t.Errorf("reducible production count is mismatched; want: %v, got: %v", len(eState.reducibleProds), len(state.reducible))
+				}
+				for _, eProd := range eState.reducibleProds {
+					if _, ok := state.reducible[eProd.id]; !ok {
+						t.Errorf("reducible production was not found: %v", eProd.id)
+					}
+				}
+
+				if len(state.emptyProdItems) != len(eState.emptyProdItems) {
+					t.Errorf("empty production item is mismatched; want: %v, got: %v", len(eState.emptyProdItems), len(state.emptyProdItems))
+				}
+				for _, eItem := range eState.emptyProdItems {
+					found := false
+					for _, item := range state.emptyProdItems {
+						if item.id != eItem.id {
+							continue
+						}
+						found = true
+						break
+					}
+					if !found {
+						t.Errorf("empty production item not found: %v", eItem.id)
+					}
+				}
+			}
+		})
+	}
+}
+
+type expectedState struct {
+	kernelItems []*lrItem
+	acts        map[symbol.Symbol]testActionEntry
+	goTos       map[symbol.Symbol][]*lrItem
+}
+
+func TestGenLALRParsingTable(t *testing.T) {
+	src := `
+#name test;
+
+s: l eq r | r;
+l: ref r | id;
+r: l;
+eq: '=';
+ref: '*';
+id: "[A-Za-z0-9_]+";
+`
+
+	var ptab *ParsingTable
+	var automaton *lalr1Automaton
+	var gram *Grammar
+	var nonTermCount int
+	var termCount int
+	{
+		ast, err := parser.Parse(strings.NewReader(src))
+		if err != nil {
+			t.Fatal(err)
+		}
+		b := GrammarBuilder{
+			AST: ast,
+		}
+		gram, err = b.build()
+		if err != nil {
+			t.Fatal(err)
+		}
+		first, err := genFirstSet(gram.productionSet)
+		if err != nil {
+			t.Fatal(err)
+		}
+		lr0, err := genLR0Automaton(gram.productionSet, gram.augmentedStartSymbol, gram.errorSymbol)
+		if err != nil {
+			t.Fatal(err)
+		}
+		automaton, err = genLALR1Automaton(lr0, gram.productionSet, first)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		nonTermTexts, err := gram.symbolTable.NonTerminalTexts()
+		if err != nil {
+			t.Fatal(err)
+		}
+		termTexts, err := gram.symbolTable.TerminalTexts()
+		if err != nil {
+			t.Fatal(err)
+		}
+		nonTermCount = len(nonTermTexts)
+		termCount = len(termTexts)
+
+		lalr := &lrTableBuilder{
+			automaton:    automaton.lr0Automaton,
+			prods:        gram.productionSet,
+			termCount:    termCount,
+			nonTermCount: nonTermCount,
+			symTab:       gram.symbolTable,
+		}
+		ptab, err = lalr.build()
+		if err != nil {
+			t.Fatalf("failed to create a LALR parsing table: %v", err)
+		}
+		if ptab == nil {
+			t.Fatal("genLALRParsingTable returns nil without any error")
+		}
+	}
+
+	genSym := newTestSymbolGenerator(t, gram.symbolTable)
+	genProd := newTestProductionGenerator(t, genSym)
+	genLR0Item := newTestLR0ItemGenerator(t, genProd)
+
+	expectedKernels := map[int][]*lrItem{
+		0: {
+			withLookAhead(genLR0Item("s'", 0, "s"), symbol.SymbolEOF),
+		},
+		1: {
+			withLookAhead(genLR0Item("s'", 1, "s"), symbol.SymbolEOF),
+		},
+		2: {
+			withLookAhead(genLR0Item("s", 1, "l", "eq", "r"), symbol.SymbolEOF),
+			withLookAhead(genLR0Item("r", 1, "l"), symbol.SymbolEOF),
+		},
+		3: {
+			withLookAhead(genLR0Item("s", 1, "r"), symbol.SymbolEOF),
+		},
+		4: {
+			withLookAhead(genLR0Item("l", 1, "ref", "r"), genSym("eq"), symbol.SymbolEOF),
+		},
+		5: {
+			withLookAhead(genLR0Item("l", 1, "id"), genSym("eq"), symbol.SymbolEOF),
+		},
+		6: {
+			withLookAhead(genLR0Item("s", 2, "l", "eq", "r"), symbol.SymbolEOF),
+		},
+		7: {
+			withLookAhead(genLR0Item("l", 2, "ref", "r"), genSym("eq"), symbol.SymbolEOF),
+		},
+		8: {
+			withLookAhead(genLR0Item("r", 1, "l"), genSym("eq"), symbol.SymbolEOF),
+		},
+		9: {
+			withLookAhead(genLR0Item("s", 3, "l", "eq", "r"), symbol.SymbolEOF),
+		},
+	}
+
+	expectedStates := []expectedState{
+		{
+			kernelItems: expectedKernels[0],
+			acts: map[symbol.Symbol]testActionEntry{
+				genSym("ref"): {
+					ty:        ActionTypeShift,
+					nextState: expectedKernels[4],
+				},
+				genSym("id"): {
+					ty:        ActionTypeShift,
+					nextState: expectedKernels[5],
+				},
+			},
+			goTos: map[symbol.Symbol][]*lrItem{
+				genSym("s"): expectedKernels[1],
+				genSym("l"): expectedKernels[2],
+				genSym("r"): expectedKernels[3],
+			},
+		},
+		{
+			kernelItems: expectedKernels[1],
+			acts: map[symbol.Symbol]testActionEntry{
+				symbol.SymbolEOF: {
+					ty:         ActionTypeReduce,
+					production: genProd("s'", "s"),
+				},
+			},
+		},
+		{
+			kernelItems: expectedKernels[2],
+			acts: map[symbol.Symbol]testActionEntry{
+				genSym("eq"): {
+					ty:        ActionTypeShift,
+					nextState: expectedKernels[6],
+				},
+				symbol.SymbolEOF: {
+					ty:         ActionTypeReduce,
+					production: genProd("r", "l"),
+				},
+			},
+		},
+		{
+			kernelItems: expectedKernels[3],
+			acts: map[symbol.Symbol]testActionEntry{
+				symbol.SymbolEOF: {
+					ty:         ActionTypeReduce,
+					production: genProd("s", "r"),
+				},
+			},
+		},
+		{
+			kernelItems: expectedKernels[4],
+			acts: map[symbol.Symbol]testActionEntry{
+				genSym("ref"): {
+					ty:        ActionTypeShift,
+					nextState: expectedKernels[4],
+				},
+				genSym("id"): {
+					ty:        ActionTypeShift,
+					nextState: expectedKernels[5],
+				},
+			},
+			goTos: map[symbol.Symbol][]*lrItem{
+				genSym("r"): expectedKernels[7],
+				genSym("l"): expectedKernels[8],
+			},
+		},
+		{
+			kernelItems: expectedKernels[5],
+			acts: map[symbol.Symbol]testActionEntry{
+				genSym("eq"): {
+					ty:         ActionTypeReduce,
+					production: genProd("l", "id"),
+				},
+				symbol.SymbolEOF: {
+					ty:         ActionTypeReduce,
+					production: genProd("l", "id"),
+				},
+			},
+		},
+		{
+			kernelItems: expectedKernels[6],
+			acts: map[symbol.Symbol]testActionEntry{
+				genSym("ref"): {
+					ty:        ActionTypeShift,
+					nextState: expectedKernels[4],
+				},
+				genSym("id"): {
+					ty:        ActionTypeShift,
+					nextState: expectedKernels[5],
+				},
+			},
+			goTos: map[symbol.Symbol][]*lrItem{
+				genSym("l"): expectedKernels[8],
+				genSym("r"): expectedKernels[9],
+			},
+		},
+		{
+			kernelItems: expectedKernels[7],
+			acts: map[symbol.Symbol]testActionEntry{
+				genSym("eq"): {
+					ty:         ActionTypeReduce,
+					production: genProd("l", "ref", "r"),
+				},
+				symbol.SymbolEOF: {
+					ty:         ActionTypeReduce,
+					production: genProd("l", "ref", "r"),
+				},
+			},
+		},
+		{
+			kernelItems: expectedKernels[8],
+			acts: map[symbol.Symbol]testActionEntry{
+				genSym("eq"): {
+					ty:         ActionTypeReduce,
+					production: genProd("r", "l"),
+				},
+				symbol.SymbolEOF: {
+					ty:         ActionTypeReduce,
+					production: genProd("r", "l"),
+				},
+			},
+		},
+		{
+			kernelItems: expectedKernels[9],
+			acts: map[symbol.Symbol]testActionEntry{
+				symbol.SymbolEOF: {
+					ty:         ActionTypeReduce,
+					production: genProd("s", "l", "eq", "r"),
+				},
+			},
+		},
+	}
+
+	t.Run("initial state", func(t *testing.T) {
+		iniState := findStateByNum(automaton.states, ptab.InitialState)
+		if iniState == nil {
+			t.Fatalf("the initial state was not found: #%v", ptab.InitialState)
+		}
+		eIniState, err := newKernel(expectedKernels[0])
+		if err != nil {
+			t.Fatalf("failed to create a kernel item: %v", err)
+		}
+		if iniState.id != eIniState.id {
+			t.Fatalf("the initial state is mismatched; want: %v, got: %v", eIniState.id, iniState.id)
+		}
+	})
+
+	for i, eState := range expectedStates {
+		t.Run(fmt.Sprintf("#%v", i), func(t *testing.T) {
+			k, err := newKernel(eState.kernelItems)
+			if err != nil {
+				t.Fatalf("failed to create a kernel item: %v", err)
+			}
+			state, ok := automaton.states[k.id]
+			if !ok {
+				t.Fatalf("state was not found: #%v", 0)
+			}
+
+			testAction(t, &eState, state, ptab, automaton.lr0Automaton, gram, termCount)
+			testGoTo(t, &eState, state, ptab, automaton.lr0Automaton, nonTermCount)
+		})
+	}
+}
+
+func testAction(t *testing.T, expectedState *expectedState, state *lrState, ptab *ParsingTable, automaton *lr0Automaton, gram *Grammar, termCount int) {
+	nonEmptyEntries := map[symbol.SymbolNum]struct{}{}
+	for eSym, eAct := range expectedState.acts {
+		nonEmptyEntries[eSym.Num()] = struct{}{}
+
+		ty, stateNum, prodNum := ptab.getAction(state.num, eSym.Num())
+		if ty != eAct.ty {
+			t.Fatalf("action type is mismatched; want: %v, got: %v", eAct.ty, ty)
+		}
+		switch eAct.ty {
+		case ActionTypeShift:
+			eNextState, err := newKernel(eAct.nextState)
+			if err != nil {
+				t.Fatal(err)
+			}
+			nextState := findStateByNum(automaton.states, stateNum)
+			if nextState == nil {
+				t.Fatalf("state was not found; state: #%v", stateNum)
+			}
+			if nextState.id != eNextState.id {
+				t.Fatalf("next state is mismatched; symbol: %v, want: %v, got: %v", eSym, eNextState.id, nextState.id)
+			}
+		case ActionTypeReduce:
+			prod := findProductionByNum(gram.productionSet, prodNum)
+			if prod == nil {
+				t.Fatalf("production was not found: #%v", prodNum)
+			}
+			if prod.id != eAct.production.id {
+				t.Fatalf("production is mismatched; symbol: %v, want: %v, got: %v", eSym, eAct.production.id, prod.id)
+			}
+		}
+	}
+	for symNum := 0; symNum < termCount; symNum++ {
+		if _, checked := nonEmptyEntries[symbol.SymbolNum(symNum)]; checked {
+			continue
+		}
+		ty, stateNum, prodNum := ptab.getAction(state.num, symbol.SymbolNum(symNum))
+		if ty != ActionTypeError {
+			t.Errorf("unexpected ACTION entry; state: #%v, symbol: #%v, action type: %v, next state: #%v, prodction: #%v", state.num, symNum, ty, stateNum, prodNum)
+		}
+	}
+}
+
+func testGoTo(t *testing.T, expectedState *expectedState, state *lrState, ptab *ParsingTable, automaton *lr0Automaton, nonTermCount int) {
+	nonEmptyEntries := map[symbol.SymbolNum]struct{}{}
+	for eSym, eGoTo := range expectedState.goTos {
+		nonEmptyEntries[eSym.Num()] = struct{}{}
+
+		eNextState, err := newKernel(eGoTo)
+		if err != nil {
+			t.Fatal(err)
+		}
+		ty, stateNum := ptab.getGoTo(state.num, eSym.Num())
+		if ty != GoToTypeRegistered {
+			t.Fatalf("GOTO entry was not found; state: #%v, symbol: #%v", state.num, eSym)
+		}
+		nextState := findStateByNum(automaton.states, stateNum)
+		if nextState == nil {
+			t.Fatalf("state was not found: #%v", stateNum)
+		}
+		if nextState.id != eNextState.id {
+			t.Fatalf("next state is mismatched; symbol: %v, want: %v, got: %v", eSym, eNextState.id, nextState.id)
+		}
+	}
+	for symNum := 0; symNum < nonTermCount; symNum++ {
+		if _, checked := nonEmptyEntries[symbol.SymbolNum(symNum)]; checked {
+			continue
+		}
+		ty, _ := ptab.getGoTo(state.num, symbol.SymbolNum(symNum))
+		if ty != GoToTypeError {
+			t.Errorf("unexpected GOTO entry; state: #%v, symbol: #%v", state.num, symNum)
+		}
+	}
+}
+
+type testActionEntry struct {
+	ty         ActionType
+	nextState  []*lrItem
+	production *production
+}
+
+func findStateByNum(states map[kernelID]*lrState, num stateNum) *lrState {
+	for _, state := range states {
+		if state.num == num {
+			return state
+		}
+	}
+	return nil
+}
+
+func findProductionByNum(prods *productionSet, num productionNum) *production {
+	for _, prod := range prods.getAllProductions() {
+		if prod.num == num {
+			return prod
+		}
+	}
+	return nil
+}
+
+type testSymbolGenerator func(text string) symbol.Symbol
+
+func newTestSymbolGenerator(t *testing.T, symTab *symbol.SymbolTableReader) testSymbolGenerator {
+	return func(text string) symbol.Symbol {
+		t.Helper()
+
+		sym, ok := symTab.ToSymbol(text)
+		if !ok {
+			t.Fatalf("symbol was not found: %v", text)
+		}
+		return sym
+	}
+}
+
+type testProductionGenerator func(lhs string, rhs ...string) *production
+
+func newTestProductionGenerator(t *testing.T, genSym testSymbolGenerator) testProductionGenerator {
+	return func(lhs string, rhs ...string) *production {
+		t.Helper()
+
+		rhsSym := []symbol.Symbol{}
+		for _, text := range rhs {
+			rhsSym = append(rhsSym, genSym(text))
+		}
+		prod, err := newProduction(genSym(lhs), rhsSym)
+		if err != nil {
+			t.Fatalf("failed to create a production: %v", err)
+		}
+
+		return prod
+	}
+}
+
+type testLR0ItemGenerator func(lhs string, dot int, rhs ...string) *lrItem
+
+func newTestLR0ItemGenerator(t *testing.T, genProd testProductionGenerator) testLR0ItemGenerator {
+	return func(lhs string, dot int, rhs ...string) *lrItem {
+		t.Helper()
+
+		prod := genProd(lhs, rhs...)
+		item, err := newLR0Item(prod, dot)
+		if err != nil {
+			t.Fatalf("failed to create a LR0 item: %v", err)
+		}
+
+		return item
+	}
+}
+
+func withLookAhead(item *lrItem, lookAhead ...symbol.Symbol) *lrItem {
+	if item.lookAhead.symbols == nil {
+		item.lookAhead.symbols = map[symbol.Symbol]struct{}{}
+	}
+
+	for _, a := range lookAhead {
+		item.lookAhead.symbols[a] = struct{}{}
+	}
+
+	return item
+}