func TestEarleyDFAEpsilons(t *testing.T) {
// Build a simple BNF grammar description grammar.
gb := parser.OpenGrammarBuilder()
gb.Name("a4").
Terminals("a").
Nonterminals("S", "A", "E").
Rule().Lhs("`*").Rhs("S", "`.").
Rule().Lhs("S").Rhs("A", "A", "A", "A").
Rule().Lhs("A").Rhs("a").
Rule().Lhs("A").Rhs("E").
Rule().Lhs("E").Rhs("`e")
g, err := gb.Build()
if err != nil {
t.Error(err)
}
grammar := parser.GetIndexedGrammar(g)
dfa, err := BuildEpsilonLR0Dfa(grammar)
if err != nil {
t.Error()
return
}
fmt.Printf("DFA has %d states\n", len(dfa.states))
for i := 0; i < len(dfa.states); i++ {
fmt.Println(dfa.states[i].String())
}
}
func TestEarleyDFA(t *testing.T) {
gb := parser.OpenGrammarBuilder()
gb.Terminals("NONTERM", "COLEQ", "PIPE", "IDENTIFIER").
Nonterminals("bnf", "ntdecl", "def", "ntort").
Rule().Lhs("bnf").Rhs("ntdecl").
Rule().Lhs("bnf").Rhs("ntdecl", "bnf").
Rule().Lhs("ntdecl").Rhs("NONTERM", "COLEQ", "def").
Rule().Lhs("ntdecl").Rhs("ntdecl", "PIPE", "def").
Rule().Lhs("def").Rhs("ntort").
Rule().Lhs("def").Rhs("ntort", "def").
Rule().Lhs("ntort").Rhs("IDENTIFIER").
Rule().Lhs("ntort").Rhs("NONTERM").
Rule().Lhs("`*").Rhs("bnf", "`.").
Name("simple-bnf")
g, err := gb.Build()
if err != nil {
t.Error(err)
}
grammar := parser.GetIndexedGrammar(g)
dfa, err := BuildEpsilonLR0Dfa(grammar)
if err != nil {
t.Error()
return
}
fmt.Printf("DFA has %d states\n", len(dfa.states))
for i := 0; i < len(dfa.states); i++ {
fmt.Println(dfa.states[i].String())
}
}
func TestNNF(t *testing.T) {
// Build a simple BNF aGrammar description aGrammar.
gb := parser.OpenGrammarBuilder()
gb.Name("a4").
Terminals("a").
Nonterminals("S", "A", "E").
Rule().Lhs("`*").Rhs("S", "`.").
Rule().Lhs("S").Rhs("A", "A", "A", "A").
Rule().Lhs("A").Rhs("a").
Rule().Lhs("A").Rhs("E").
Rule().Lhs("E").Rhs("`e")
g, err := gb.Build()
if err != nil {
t.Error(err)
return
}
var aGrammar parser.Grammar
var rTransform parser.SyntaxTreeTransform
nnf, err := IsNihilisticNormalForm(g)
if err != nil {
t.Error()
return
}
if !nnf {
fmt.Println("Grammar is not NNF, transforming.")
aGrammar, rTransform, err = GetNihilisticAugmentGrammar(g)
if err != nil {
t.Error(err)
return
}
} else {
t.Error("Grammar returned NNF.")
return
}
fmt.Println("Name: " + aGrammar.Name())
terms := make([]string, aGrammar.NumTerminals())
for i, t := range aGrammar.Terminals() {
terms[i] = t.String()
}
nterms := make([]string, aGrammar.NumNonterminals())
for i, t := range aGrammar.Nonterminals() {
nterms[i] = t.String()
}
fmt.Println("Terminals: " + strings.Join(terms, ", "))
fmt.Println("Nonterminals: " + strings.Join(nterms, ", "))
fmt.Println("Productions:")
for _, p := range aGrammar.Productions() {
fmt.Println(" " + p.String())
}
rTransform = rTransform
}
func TestGrammarIndex(t *testing.T) {
// Build a simple BNF grammar description grammar.
gb := parser.OpenGrammarBuilder()
gb.Terminals("NONTERM", "COLEQ", "PIPE", "IDENTIFIER").
Nonterminals("bnf", "ntdecl", "def", "ntort").
Rule().Lhs("bnf").Rhs("ntdecl").
Rule().Lhs("bnf").Rhs("ntdecl", "bnf").
Rule().Lhs("ntdecl").Rhs("NONTERM", "COLEQ", "def").
Rule().Lhs("ntdecl").Rhs("ntdecl", "PIPE", "def").
Rule().Lhs("def").Rhs("ntort").
Rule().Lhs("def").Rhs("ntort", "def").
Rule().Lhs("ntort").Rhs("IDENTIFIER").
Rule().Lhs("ntort").Rhs("NONTERM").
Rule().Lhs("`*").Rhs("bnf", "`.").
Name("simple-bnf")
g, err := gb.Build()
if err != nil {
t.Error(err)
}
grammar := parser.GetIndexedGrammar(g)
fmt.Printf("`*: 0x%8.8X\n", grammar.Asterisk())
dfa, err := BuildDfa(grammar, false)
if err != nil {
t.Error(err)
return
}
fmt.Printf("DFA has %d states\n", len(dfa.states))
for i := 0; i < len(dfa.states); i++ {
fmt.Println(dfa.states[i])
}
fmt.Println("Done.")
}
func TestParser(t *testing.T) {
gb := parser.OpenGrammarBuilder()
gb.Terminals("NONTERM", "COLEQ", "PIPE", "IDENTIFIER").
Nonterminals("bnf", "ntdecl", "def", "ntort").
Rule().Lhs("bnf").Rhs("ntdecl").
Rule().Lhs("bnf").Rhs("ntdecl", "bnf").
Rule().Lhs("ntdecl").Rhs("NONTERM", "COLEQ", "def").
Rule().Lhs("ntdecl").Rhs("ntdecl", "PIPE", "def").
Rule().Lhs("def").Rhs("ntort").
Rule().Lhs("def").Rhs("ntort", "def").
Rule().Lhs("ntort").Rhs("IDENTIFIER").
Rule().Lhs("ntort").Rhs("NONTERM").
Rule().Lhs("`*").Rhs("bnf", "`.").
Name("simple-bnf")
g, err := gb.Build()
if err != nil {
t.Error(err)
}
metaBnf := `
<bnf> := <ntdecl>
| <ntdecl> <bnf>
<ntdecl> := NONTERM COLEQ <def>
| <ntdecl> PIPE <def>
<def> := <ntort>
| <ntort> <def>
<ntort> := IDENTIFIER
| NONTERM
`
lexer, err := NewSimpleBnfLexer(g)
if err != nil {
t.Error(err)
return
}
lexer.Reset(parser.NewStringReader(metaBnf))
p, err := GenerateParser(g)
if err != nil {
t.Error(err)
return
}
var ast parser.SyntaxTreeNode
ast, err = p.Parse(lexer, nil)
if err != nil {
t.Error(err)
return
}
fmt.Println("Got AST.")
fmt.Printf("Top is: %s\n", ast.Part())
cmap := make(map[parser.SyntaxTreeNode]int)
outmap := make(map[int]string)
var cnid, chid int
DumpTree(ast.(*astNode))
stack := []parser.SyntaxTreeNode{ast}
for len(stack) > 0 {
var buf []byte
cn := stack[len(stack)-1]
stack = stack[0 : len(stack)-1]
if id, has := cmap[cn]; !has {
cnid = len(cmap)
cmap[cn] = cnid
} else {
cnid = id
}
var desc string
if cn.Part() == nil {
desc = "-"
} else {
desc = cn.Part().String()
}
var valstr string
if cn.NumChildren() == 0 {
if vt, isVal := cn.Part().(*parser.ValueTerminal); isVal {
val := vt.Value()
if s, isStr := val.(string); isStr {
valstr = fmt.Sprintf("\"%s\"", s)
} else if s, isStr := val.(parser.Stringable); isStr {
valstr = fmt.Sprintf("\"%s\"", s.String())
} else {
valstr = fmt.Sprintf("0x%8.8X", reflect.ValueOf(val).Pointer())
}
} else {
valstr = "-"
}
var teststr string
if cn.(*astNode).left == nil {
teststr = "."
} else {
teststr = fmt.Sprintf("%d", cn.(*astNode).left.first)
}
buf = append(buf, fmt.Sprintf("[%d: leaf %s %s %s (%d-%d)]", cnid, teststr, desc, valstr, cn.First(), cn.Last())...)
} else {
buf = append(buf, fmt.Sprintf("[%d: %s {", cnid, cn.Rule().String())...)
for i := 0; i < cn.NumChildren(); i++ {
child := cn.Child(i)
stack = append(stack, child)
if id, has := cmap[child]; !has {
chid = len(cmap)
cmap[child] = chid
} else {
chid = id
}
buf = append(buf, fmt.Sprintf("%d", chid)...)
if i < cn.NumChildren()-1 {
buf = append(buf, ","...)
}
}
buf = append(buf, fmt.Sprintf("} (%d-%d)]", cn.First(), cn.Last())...)
}
outmap[cnid] = string(buf)
}
for i := 0; i < len(outmap); i++ {
fmt.Println(outmap[i])
}
}
func TestRelex(t *testing.T) {
gb := parser.OpenGrammarBuilder()
gb.Name("simple-calculator").
Terminals("ID", "EQ", "PRINT", "POW", "PLUS", "MINUS", "TIMES", "DIV", "MOD", "LP", "RP", "NUM").
Nonterminals("program", "statement", "assignment", "output", "expr", "aopfree", "aop",
"mopfree", "mop", "unit").
Rule().Lhs("`*").Rhs("program", "`.").
Rule().Lhs("program").Rhs("statement").
Value(func(p parser.Production, values []interface{}) (interface{}, error) {
return &StatementList{statements: []Statement{values[0].(Statement)}}, nil
}).
Rule().Lhs("program").Rhs("statement", "program").
Value(func(p parser.Production, values []interface{}) (interface{}, error) {
slist := values[1].(*StatementList)
slist.statements = append(slist.statements, values[0].(Statement))
return slist, nil
}).
Rule().Lhs("statement").Rhs("assignment").
Rule().Lhs("statement").Rhs("output").
Rule().Lhs("assignment").Rhs("ID", "EQ", "expr").
Value(func(p parser.Production, values []interface{}) (interface{}, error) {
return &Assignment{varname: values[0].(parser.Stringable).String(),
value: values[2].(Expression)}, nil
}).
Rule().Lhs("output").Rhs("PRINT", "expr").
Value(func(p parser.Production, values []interface{}) (interface{}, error) {
return &Output{value: values[1].(Expression)}, nil
}).
Rule().Lhs("expr").Rhs("aopfree").
Rule().Lhs("expr").Rhs("expr", "aop", "aopfree").Value(binaryOpCtor).
Rule().Lhs("aopfree").Rhs("aopfree", "mop", "mopfree").Value(binaryOpCtor).
Rule().Lhs("mopfree").Rhs("mopfree", "POW", "unit").Value(binaryOpCtor).
Rule().Lhs("aop").Rhs("PLUS").
Rule().Lhs("aop").Rhs("MINUS").
Rule().Lhs("mop").Rhs("TIMES").
Rule().Lhs("mop").Rhs("DIV").
Rule().Lhs("mop").Rhs("MOD").
Rule().Lhs("unit").Rhs("ID").
Value(func(p parser.Production, values []interface{}) (interface{}, error) {
return &VariableExpression{varname: values[0].(parser.Stringable).String()}, nil
}).
Rule().Lhs("unit").Rhs("MINUS", "unit").
Value(func(p parser.Production, values []interface{}) (interface{}, error) {
return &Negation{arg: values[1].(Expression)}, nil
}).
Rule().Lhs("unit").Rhs("LP", "expr", "RP").
Value(func(p parser.Production, values []interface{}) (interface{}, error) {
return values[1], nil
}).
Rule().Lhs("unit").Rhs("NUM").
Value(func(p parser.Production, values []interface{}) (interface{}, error) {
return &Literal{val: values[0].(*big.Int)}, nil
})
g, err := gb.Build()
if err != nil {
t.Error(err)
return
}
p, err := earley.GenerateParser(g)
if err != nil {
t.Error("parser generation failed: " + err.Error())
return
}
fmt.Println(g.Name())
lb := OpenLexerBuilder(g)
lb.Token("ID").Expr(`([a-zA-Z][a-zA-Z0-9]*)`)
lb.Token("EQ").Expr(`=`)
lb.Token("PRINT").Expr(`print`)
lb.Token("POW").Expr(`^`).
Value(func(part parser.GrammarParticle, match string) interface{} {
return EXPONENTIATION
})
lb.Token("PLUS").Expr(`\+`).
Value(func(part parser.GrammarParticle, match string) interface{} {
return ADDITION
})
lb.Token("MINUS").Expr(`-`).
Value(func(part parser.GrammarParticle, match string) interface{} {
return SUBTRACTION
})
lb.Token("TIMES").Expr(`\*`).
Value(func(part parser.GrammarParticle, match string) interface{} {
return MULTIPLICATION
})
lb.Token("DIV").Expr(`/`).
Value(func(part parser.GrammarParticle, match string) interface{} {
return DIVISION
})
lb.Token("MOD").Expr(`%`).
Value(func(part parser.GrammarParticle, match string) interface{} {
return MODULUS
})
lb.Token("LP").Expr(`\(`)
lb.Token("RP").Expr(`\)`)
lb.Token("NUM").Expr("(0|[1-9][0-9]*)").
Value(func(part parser.GrammarParticle, match string) interface{} {
n := big.NewInt(0)
ten := big.NewInt(10)
for i := len(match) - 1; i >= 0; i-- {
n.Mul(n, ten).Add(n, big.NewInt(int64(match[i]-'0')))
}
return n
})
lexer, err := lb.Build()
if err != nil {
t.Error("lexer build failed: " + err.Error())
return
}
lexer.Reset(parser.NewStringReader(SAMPLE_PROGRAM))
ast, err := p.Parse(lexer, nil)
if err != nil {
t.Error(err)
return
}
ast = ast
}
func GetNihilisticAugmentGrammar(g parser.Grammar) (parser.Grammar, parser.SyntaxTreeTransform, error) {
exceptionalEpsilons := []parser.GrammarParticle{}
idxg := parser.GetIndexedGrammar(g)
idx, err := idxg.GetIndex(index.BASIC_INDEX)
if err != nil {
return nil, nil, err
}
bidx := idx.(*index.BasicGrammarIndex)
idx, err = idxg.GetIndex(index.NAME_INDEX)
if err != nil {
return nil, nil, err
}
nidx := idx.(*index.NameIndex)
for _, nt := range idxg.Nonterminals() {
n, err := IsNihilistic(nt)
if err != nil {
return nil, nil, err
}
if bidx.Epsilon(nt) && !n {
exceptionalEpsilons = append(exceptionalEpsilons, nt)
}
}
gb := parser.OpenGrammarBuilder()
for _, nt := range g.Nonterminals() {
if nt.Asterisk() {
continue
}
gb.Nonterminals(nt.Name())
}
for _, t := range g.Terminals() {
if t.Epsilon() {
continue
}
gb.Terminals(t.Name())
}
augmentMap := make(map[string]string)
invMap := make(map[string]string)
for _, e := range exceptionalEpsilons {
eName := e.Name() + "-ε"
augmentMap[e.Name()] = eName
invMap[eName] = e.Name()
gb.Nonterminals(eName)
//gb.Rule().Lhs(eName).Rhs("`e")
}
for _, nt := range g.Nonterminals() {
for i := 0; i < bidx.NumLhsStarts(nt); i++ {
prod := bidx.LhsStart(nt, i)
//fmt.Printf("LHSTART(%s,%d): %s\n", nt.String(), i, prod.String())
exIdx := []int{}
rhs := []string{}
for j := 0; j < prod.RhsLen(); j++ {
t := prod.Rhs(j)
if _, has := augmentMap[t.Name()]; has {
exIdx = append(exIdx, j)
//fmt.Println("exidx gets "+t.String())
}
rhs = append(rhs, t.Name())
}
if nt.Asterisk() { // Initial rule is special-cased.
//fmt.Println("rule transfers: "+prod.String())
//fmt.Println("Args: {"+prod.Lhs(0).Name()+"}, {"+strings.Join(rhs,",")+"}")
gb.Rule().Lhs(prod.Lhs(0).Name()).Rhs(rhs...)
initSym := nidx.Nonterminal(rhs[0])
if initSym != nil {
if bidx.Epsilon(initSym) {
gb.Rule().Lhs(initSym.Name()).Rhs(augmentMap[initSym.Name()])
}
}
} else {
rhsinst := make([]string, len(rhs))
//fmt.Printf("index len %d\n", len(exIdx))
s := cnt.FirstSelection(uint(len(exIdx)))
for {
nnCount := 0
for j := 0; j < len(rhs); j++ {
rhsinst[j] = rhs[j]
if nidx.Terminal(rhs[j]) != nil {
nnCount++
} else {
nt := nidx.Nonterminal(rhs[j])
nihil, err := IsNihilistic(nt)
if err != nil {
return nil, nil, err
}
if !nihil {
nnCount++
}
}
}
copy(rhsinst, rhs)
for j := 0; j < len(exIdx); j++ {
if s.Test(j) {
//fmt.Printf("idx %d replacement: %s->%s\n", exIdx[j], rhsinst[exIdx[j]], augmentMap[rhsinst[exIdx[j]]])
rhsinst[exIdx[j]] = augmentMap[rhsinst[exIdx[j]]]
nnCount--
}
}
var head string
if nnCount == 0 {
head = augmentMap[prod.Lhs(0).Name()]
} else {
head = prod.Lhs(0).Name()
}
//fmt.Println("rule transforms: "+prod.String())
//fmt.Println("Args: {"+head+"}, {"+strings.Join(rhs,",")+"}")
gb.Rule().Lhs(head).Rhs(rhsinst...)
if s.HasNext() {
s = s.Next()
} else {
break
}
}
}
}
}
gb.Name(g.Name() + "-ε")
augmentedGrammar, err := gb.Build()
if err != nil {
return nil, nil, err
}
augidx := parser.GetIndexedGrammar(augmentedGrammar)
idx, err = augidx.GetIndex(index.NAME_INDEX)
if err != nil {
return nil, nil, err
}
anidx := idx.(*index.NameIndex)
idx, err = augidx.GetIndex(index.BASIC_INDEX)
if err != nil {
return nil, nil, err
}
abidx := idx.(*index.BasicGrammarIndex)
reverseMap := make(map[parser.GrammarParticle]parser.GrammarParticle)
for k, v := range augmentMap {
reverseMap[anidx.Nonterminal(v)] = nidx.Nonterminal(k)
}
prodMap := make(map[parser.Production]parser.Production)
for _, p := range augmentedGrammar.Productions() {
// Ignore the special case start rule for grammars that accept nil input.
if p.LhsLen() == 1 && p.RhsLen() == 1 {
initSym := abidx.LhsStart(augmentedGrammar.Asterisk(), 0).Rhs(0)
if p.Lhs(0) == initSym && invMap[p.Rhs(0).Name()] == initSym.Name() {
continue
}
}
if p.RhsLen() == 1 && p.Rhs(0).Epsilon() {
continue
}
rhs := make([]string, 0, p.RhsLen())
for i := 0; i < p.RhsLen(); i++ {
rp := p.Rhs(i)
if ot, has := reverseMap[rp]; has {
rhs = append(rhs, ot.Name())
} else {
rhs = append(rhs, rp.Name())
}
}
//fmt.Printf("Searching for preimage rhs %s\n", strings.Join(rhs,","))
var target parser.Production
for _, cp := range nidx.RhsNames(rhs) {
//fmt.Println(" considering "+cp.String())
//for _, p := range g.Productions() {
//fmt.Println(p.String())
//}
if nt, has := reverseMap[p.Lhs(0)]; has {
if cp.Lhs(0) == nt {
target = cp
break
}
} else {
if cp.Lhs(0).Name() == p.Lhs(0).Name() {
target = cp
break
}
}
}
if target == nil {
return nil, nil, errors.New("Could not find preimage of augmented production rule: " + p.String())
}
prodMap[p] = target
}
var rtrans func(treeNode parser.SyntaxTreeNode) (parser.SyntaxTreeNode, error)
rtrans = func(treeNode parser.SyntaxTreeNode) (parser.SyntaxTreeNode, error) {
part := treeNode.Part()
if op, has := reverseMap[part]; has {
part = op
}
exp := make([]parser.SyntaxTreeNode, treeNode.NumChildren())
for i := 0; i < len(exp); i++ {
st := treeNode.Child(i)
if _, has := reverseMap[st.Part()]; has {
r, err := rtrans(st)
if err != nil {
return nil, err
}
exp[i] = r
} else {
exp[i] = st
}
}
return &parser.BasicSyntaxTreeNode{
Particle: part,
FirstTokenIdx: treeNode.First(),
LastTokenIdx: treeNode.Last(),
SyntacticValue: treeNode.Value(),
Prod: prodMap[treeNode.Rule()],
Expansion: exp,
}, nil
}
return augmentedGrammar, rtrans, nil
}
func TestGrammarIndex(t *testing.T) {
// Build a simple BNF grammar description grammar.
gb := parser.OpenGrammarBuilder()
gb.Terminals("NONTERM", "COLEQ", "PIPE", "IDENTIFIER").
Nonterminals("bnf", "ntdecl", "def", "ntort").
Rule().Lhs("bnf").Rhs("ntdecl").
Rule().Lhs("bnf").Rhs("ntdecl", "bnf").
Rule().Lhs("ntdecl").Rhs("NONTERM", "COLEQ", "def").
Rule().Lhs("ntdecl").Rhs("ntdecl", "PIPE", "def").
Rule().Lhs("def").Rhs("ntort").
Rule().Lhs("def").Rhs("ntort", "def").
Rule().Lhs("ntort").Rhs("IDENTIFIER").
Rule().Lhs("ntort").Rhs("NONTERM").
Rule().Lhs("`*").Rhs("bnf", "`.").
Name("simple-bnf")
g, err := gb.Build()
if err != nil {
t.Error(err)
}
grammar := parser.GetIndexedGrammar(g)
fmt.Println("Name: " + grammar.Name())
terms := make([]string, grammar.NumTerminals())
for i, t := range grammar.Terminals() {
terms[i] = t.String()
}
nterms := make([]string, grammar.NumNonterminals())
for i, t := range grammar.Nonterminals() {
nterms[i] = t.String()
}
fmt.Println("Terminals: " + strings.Join(terms, ", "))
fmt.Println("Nonterminals: " + strings.Join(nterms, ", "))
fmt.Println("Productions:")
for _, p := range grammar.Productions() {
fmt.Println(" " + p.String())
}
idx, err := grammar.GetIndex("basic")
if err != nil {
t.Error()
return
}
basicIndex := idx.(*BasicGrammarIndex)
fmt.Println("Basic index type: '" + basicIndex.IndexName() + "'")
fmt.Println("Production RHS starts: ")
for idx := 0; idx < grammar.NumTerminals(); idx++ {
term := grammar.Terminal(idx)
starts := basicIndex.RhsStarts(term)
if len(starts) == 0 {
continue
}
fmt.Println(" " + term.String() + ":")
for _, p := range starts {
fmt.Println(" " + p.String())
}
}
fmt.Println("\nProduction RHS ends: ")
for idx := 0; idx < grammar.NumTerminals(); idx++ {
term := grammar.Terminal(idx)
starts := basicIndex.RhsEnds(term)
if len(starts) == 0 {
continue
}
fmt.Println(" " + term.String() + ":")
for _, p := range starts {
fmt.Println(" " + p.String())
}
}
fmt.Println("\nProduction RHS contains: ")
for idx := 0; idx < grammar.NumTerminals(); idx++ {
term := grammar.Terminal(idx)
starts := basicIndex.RhsContains(term)
if len(starts) == 0 {
continue
}
fmt.Println(" " + term.String() + ":")
for _, p := range starts {
fmt.Println(" " + p.String())
}
}
fmt.Println("Grammar class:")
idx, err = grammar.GetIndex(GRAMMAR_CLASS_INDEX)
if err != nil {
t.Error(err)
return
}
gcidx := idx.(*GrammarClassIndex)
fmt.Println(" type: " + gcidx.Class().String())
fmt.Println(" regularity: " + gcidx.Regularity().String())
idx, err = grammar.GetIndex(FIRST_FOLLOW_INDEX)
if err != nil {
t.Error(err)
return
}
ffidx := idx.(*FFIndex)
fmt.Println("FIRST(x): ")
for _, p := range g.Nonterminals() {
fmt.Println(" " + p.String())
for _, k := range ffidx.Firsts(p) {
fmt.Println(" " + k.String())
}
}
fmt.Println("FOLLOW(x): ")
for _, p := range g.Nonterminals() {
fmt.Println(" " + p.String())
for _, k := range ffidx.Follows(p) {
fmt.Println(" " + k.String())
}
}
for _, p := range g.Terminals() {
fmt.Println(" " + p.String())
for _, k := range ffidx.Firsts(p) {
fmt.Println(" " + k.String())
}
}
}