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 (gci *GrammarClassIndex) Initialize(g parser.Grammar) error {
gci.g = g
gci.gclass = parser.CONSTANT
gci.greg = parser.STRICT_UNITARY
for _, p := range g.Productions() {
if p.Lhs(0).Asterisk() {
continue
}
preg := parser.GetProductionClass(p)
if preg > gci.gclass {
gci.gclass = preg
if gci.gclass > parser.REGULAR {
gci.greg = parser.NONREGULAR
}
}
if gci.gclass <= parser.REGULAR {
gci.greg = gci.greg.Join(parser.GetProductionRegularity(p))
}
}
return nil
}
func (ni *NameIndex) Initialize(g parser.Grammar) error {
ni.nonterminalsByName = make(map[string]parser.GrammarParticle)
ni.terminalsByName = make(map[string]parser.GrammarParticle)
for i := 0; i < g.NumNonterminals(); i++ {
nt := g.Nonterminal(i)
ni.nonterminalsByName[nt.Name()] = nt
}
for i := 0; i < g.NumTerminals(); i++ {
t := g.Terminal(i)
ni.terminalsByName[t.Name()] = t
}
ni.lhsNames = make(map[string][]parser.Production)
ni.rhsNames = make(map[string][]parser.Production)
for _, p := range g.Productions() {
var rhs, lhs []byte
for i := 0; i < p.LhsLen(); i++ {
lhs = append(lhs, p.Lhs(i).Name()...)
if i < p.LhsLen()-1 {
lhs = append(lhs, "|"...)
}
}
if _, has := ni.lhsNames[string(lhs)]; !has {
ni.lhsNames[string(lhs)] = []parser.Production{}
}
ni.lhsNames[string(lhs)] = append(ni.lhsNames[string(lhs)], p)
for i := 0; i < p.RhsLen(); i++ {
rhs = append(rhs, p.Rhs(i).Name()...)
if i < p.RhsLen()-1 {
rhs = append(rhs, "|"...)
}
}
if _, has := ni.rhsNames[string(rhs)]; !has {
ni.rhsNames[string(rhs)] = []parser.Production{}
}
ni.rhsNames[string(rhs)] = append(ni.rhsNames[string(rhs)], p)
}
return nil
}
func (bgi *BasicGrammarIndex) Initialize(g parser.Grammar) error {
bgi.grammar = g
bgi.epsilons = make(map[parser.GrammarParticle]parser.Production)
bgi.lhsIncludes = make(map[parser.GrammarParticle][]parser.Production)
bgi.rhsIncludes = make(map[parser.GrammarParticle][]parser.Production)
bgi.lhsStarts = make(map[parser.GrammarParticle][]parser.Production)
bgi.rhsStarts = make(map[parser.GrammarParticle][]parser.Production)
bgi.lhsEnds = make(map[parser.GrammarParticle][]parser.Production)
bgi.rhsEnds = make(map[parser.GrammarParticle][]parser.Production)
lhicn := make(map[parser.GrammarParticle]map[parser.Production]int)
rhicn := make(map[parser.GrammarParticle]map[parser.Production]int)
for _, p := range g.Productions() {
if p.LhsLen() == 1 && p.Lhs(0).Asterisk() {
bgi.lhsStarts[p.Lhs(0)] = []parser.Production{p}
bgi.lhsEnds[p.Lhs(0)] = []parser.Production{p}
bgi.rhsStarts[p.Lhs(0)] = []parser.Production{p}
if _, has := bgi.rhsStarts[p.Rhs(0)]; !has {
bgi.rhsStarts[p.Rhs(0)] = []parser.Production{}
}
bgi.rhsIncludes[p.Rhs(0)] = append(bgi.rhsIncludes[p.Rhs(0)], p)
if _, has := bgi.rhsIncludes[p.Rhs(0)]; !has {
bgi.rhsIncludes[p.Rhs(0)] = []parser.Production{}
}
bgi.rhsIncludes[p.Rhs(1)] = []parser.Production{p}
bgi.rhsEnds[p.Rhs(1)] = []parser.Production{p}
continue
}
if p.LhsLen() == 1 && p.Lhs(0).Nonterminal() && p.RhsLen() == 1 && p.Rhs(0).Epsilon() {
bgi.epsilons[p.Lhs(0)] = p
}
iterm := p.Lhs(0)
bgi.lhsStarts[iterm] = append(bgi.lhsStarts[iterm], p)
eterm := p.Lhs(p.LhsLen() - 1)
bgi.lhsEnds[eterm] = append(bgi.lhsEnds[eterm], p)
iterm = p.Rhs(0)
bgi.rhsStarts[iterm] = append(bgi.rhsStarts[iterm], p)
eterm = p.Rhs(p.RhsLen() - 1)
bgi.rhsEnds[eterm] = append(bgi.rhsEnds[eterm], p)
for idx := 0; idx < p.LhsLen(); idx++ {
pt := p.Lhs(idx)
if m, has := lhicn[pt]; !has {
m = make(map[parser.Production]int)
m[p] = 1
lhicn[pt] = m
} else {
lhicn[pt][p] = 1
}
}
for idx := 0; idx < p.RhsLen(); idx++ {
pt := p.Rhs(idx)
if m, has := rhicn[pt]; !has {
m = make(map[parser.Production]int)
m[p] = 1
rhicn[pt] = m
} else {
rhicn[pt][p] = 1
}
}
}
for pt, set := range lhicn {
slc := make([]parser.Production, 0, len(set))
for p, _ := range set {
slc = append(slc, p)
}
bgi.lhsIncludes[pt] = slc
}
for pt, set := range rhicn {
slc := make([]parser.Production, 0, len(set))
for p, _ := range set {
slc = append(slc, p)
}
bgi.rhsIncludes[pt] = slc
}
// Close epsilons.
changed := true
for changed {
changed = false
for _, p := range g.Productions() {
if p.LhsLen() != 1 || !p.Lhs(0).Nonterminal() {
continue
}
nt := p.Lhs(0)
if bgi.Epsilon(nt) {
continue
}
neweps := true
for i := 0; i < p.RhsLen(); i++ {
t := p.Rhs(i)
if !t.Nonterminal() || !bgi.Epsilon(t) {
neweps = false
break
}
}
if neweps {
bgi.epsilons[nt] = p
changed = true
}
}
}
return nil
}
func (ff *FFIndex) Initialize(g parser.Grammar) error {
ff.grammar = g
index := parser.GetIndexedGrammar(g)
idx, err := index.GetIndex(GRAMMAR_CLASS_INDEX)
if err != nil {
return err
}
cidx := idx.(*GrammarClassIndex)
if cidx.Class() >= parser.CONTEXT_SENSITIVE {
return errors.New("cannot first/follow index a non-context-free grammar")
}
idx, err = index.GetIndex(BASIC_INDEX)
bidx := idx.(*BasicGrammarIndex)
if err != nil {
return err
}
// FIRST set calculation
ff.firstSets = make(map[parser.GrammarParticle][]parser.GrammarParticle)
for _, nt := range index.Nonterminals() {
fs := tree.NewTree()
ntseen := tree.NewTree()
ntpending := []parser.GrammarParticle{nt}
for len(ntpending) > 0 {
cnt := ntpending[0]
ntpending = ntpending[1:]
for i := 0; i < bidx.NumLhsStarts(cnt); i++ {
p := bidx.LhsStart(cnt, i)
for j := 0; j < p.RhsLen(); j++ {
rt := p.Rhs(j)
if rt.Terminal() {
fs.Insert(rt)
break
} else if rt.Nonterminal() {
if _, has := ntseen.Lookup(c.LTE, rt); !has {
ntseen.Insert(rt)
fs.Insert(rt)
ntpending = append(ntpending, rt)
}
if !bidx.Epsilon(rt) {
break
}
} else {
break
}
}
}
}
ff.firstSets[nt] = make([]parser.GrammarParticle, 0, fs.Size())
for c := fs.First(); c.HasNext(); {
ff.firstSets[nt] = append(ff.firstSets[nt], c.Next().(parser.GrammarParticle))
}
}
// LAST set calculation
ff.lastSets = make(map[parser.GrammarParticle][]parser.GrammarParticle)
for _, nt := range index.Nonterminals() {
fs := tree.NewTree()
ntseen := tree.NewTree()
ntpending := []parser.GrammarParticle{nt}
for len(ntpending) > 0 {
cnt := ntpending[0]
ntpending = ntpending[1:]
for i := 0; i < bidx.NumLhsStarts(cnt); i++ {
p := bidx.LhsStart(cnt, i)
for j := p.RhsLen() - 1; j >= 0; j-- {
rt := p.Rhs(j)
if rt.Terminal() {
fs.Insert(rt)
break
}
if rt.Nonterminal() {
if _, has := ntseen.Lookup(c.LTE, rt); !has {
ntseen.Insert(rt)
fs.Insert(rt)
ntpending = append(ntpending, rt)
if !bidx.Epsilon(rt) {
break
}
}
}
}
}
}
ff.lastSets[nt] = make([]parser.GrammarParticle, 0, fs.Size())
for c := fs.First(); c.HasNext(); {
ff.lastSets[nt] = append(ff.lastSets[nt], c.Next().(parser.GrammarParticle))
}
}
// IN set calculation
ff.inSets = make(map[parser.GrammarParticle][]parser.GrammarParticle)
for _, nt := range index.Nonterminals() {
fs := tree.NewTree()
ntseen := tree.NewTree()
ntpending := []parser.GrammarParticle{nt}
for len(ntpending) > 0 {
cnt := ntpending[0]
ntpending = ntpending[1:]
for i := 0; i < bidx.NumLhsStarts(cnt); i++ {
p := bidx.LhsStart(cnt, i)
for j := p.RhsLen() - 1; j >= 0; j-- {
rt := p.Rhs(j)
if rt.Terminal() {
fs.Insert(rt)
}
if rt.Nonterminal() {
if _, has := ntseen.Lookup(c.LTE, rt); !has {
ntseen.Insert(rt)
fs.Insert(rt)
ntpending = append(ntpending, rt)
}
}
}
}
}
ff.inSets[nt] = make([]parser.GrammarParticle, 0, fs.Size())
for c := fs.First(); c.HasNext(); {
ff.inSets[nt] = append(ff.inSets[nt], c.Next().(parser.GrammarParticle))
}
}
// FOLLOW set calculation
followRefs := make(map[parser.GrammarParticle]tree.Tree)
followSets := make(map[parser.GrammarParticle]tree.Tree)
for _, p := range g.Productions() { // First-pass.
for i := 0; i < p.RhsLen()-1; i++ {
for j := i + 1; j < p.RhsLen(); j++ {
if _, has := followSets[p.Rhs(i)]; !has {
followSets[p.Rhs(i)] = tree.NewTree()
}
followSets[p.Rhs(i)].Insert(p.Rhs(j))
if !bidx.Epsilon(p.Rhs(j)) {
break
}
}
}
tp := p.Rhs(p.RhsLen() - 1)
if _, has := followRefs[tp]; !has {
followRefs[tp] = tree.NewTree()
}
followRefs[tp].Insert(p.Lhs(0))
}
var changed bool = true
for changed { // Take closure.
changed = false
for p, prt := range followRefs {
for cr := prt.First(); cr.HasNext(); {
fp := cr.Next().(parser.GrammarParticle) // x in Follow(fp) -> x in Follow(p)
if fromSet, has := followSets[fp]; has {
if _, has := followSets[p]; !has {
followSets[p] = tree.NewTree()
}
for k := fromSet.First(); k.HasNext(); {
x := k.Next().(parser.GrammarParticle)
if _, has := followSets[p].Lookup(c.LTE, x); !has {
changed = true
followSets[p].Insert(x)
}
}
}
}
}
}
ff.followSets = make(map[parser.GrammarParticle][]parser.GrammarParticle)
for r, v := range followSets { // Collect results.
ff.followSets[r] = make([]parser.GrammarParticle, 0, v.Size())
for c := v.First(); c.HasNext(); {
ff.followSets[r] = append(ff.followSets[r], c.Next().(parser.GrammarParticle))
}
}
return nil
}
