func (p *Parser) computeReachableItemSetKernels(itemSet *ItemSet) ([]syms.SymbolID, map[syms.SymbolID]ItemSet) {
sym2isker := make(map[syms.SymbolID]ItemSet)
for _, dotRule := range sortedDotRules(*itemSet) {
rhs := p.Rules.Get(dotRule.ruleID).RHS
if dotRule.dotPos >= len(rhs) {
continue
}
dotSymbol := rhs[dotRule.dotPos]
newDotRule := DotRule{dotRule.ruleID, dotRule.dotPos + 1}
if isker, ok := sym2isker[dotSymbol]; ok {
isker.dotRules[newDotRule] = true // is a kernel rule
} else {
isker = ItemSet{
make(map[DotRule]bool),
make(map[syms.SymbolID]ItemSetID),
}
isker.dotRules[newDotRule] = true // is a kernel rule
sym2isker[dotSymbol] = isker
}
}
symbols := make([]syms.SymbolID, len(sym2isker))
symIndex := 0
for sid := range sym2isker {
symbols[symIndex] = sid
symIndex++
}
symbols = syms.SortedSymbols(symbols)
return symbols, sym2isker
}
func (p *Parser) sprintTransitions(transitions map[syms.SymbolID]ItemSetID) string {
var b bytes.Buffer
symbols := make([]syms.SymbolID, 0, 0)
for sid := range transitions {
symbols = append(symbols, sid)
}
for _, sid := range syms.SortedSymbols(symbols) {
b.WriteString(fmt.Sprint(p.Syms.Get(sid).Name, " -> ", transitions[sid], " ; "))
}
return b.String()
}
func (p *Parser) symNames(m map[syms.SymbolID]Action) []string {
fsid := make([]syms.SymbolID, 0, 10)
for sid := range m {
fsid = append(fsid, sid)
}
f := make([]string, 0, 10)
for _, sid := range syms.SortedSymbols(fsid) {
str := p.Syms.Get(sid).Name
f = append(f, str)
}
return f
}
func (p *Parser) buildParseTable() error {
// defer tlog.FuncLog(tlog.Func("buildParseTable"))
symNames := func(m map[syms.SymbolID]bool) []string {
fsid := make([]syms.SymbolID, 0, 10)
for sid := range m {
fsid = append(fsid, sid)
}
f := make([]string, 0, 10)
for _, sid := range syms.SortedSymbols(fsid) {
f = append(f, p.Syms.Get(sid).Name)
}
return f
}
// build first sets for extended symbols
first := make(map[ExtSymbol]map[syms.SymbolID]bool)
{
addFirst := func(sym ExtSymbol, symfirst syms.SymbolID) bool {
m, ok := first[sym]
if !ok {
m = make(map[syms.SymbolID]bool)
first[sym] = m
}
if _, exists := m[symfirst]; exists {
return false
}
m[symfirst] = true
return true
}
for _, extrule := range p.extRules {
for _, exts := range extrule.rhs {
if p.Syms.Get(exts.symbolID).IsTerm {
addFirst(exts, exts.symbolID)
}
}
}
loop := true
for loop {
loop = false
for i := len(p.extRules) - 1; i >= 0; i-- {
extrule := p.extRules[i]
// fmt.Println("test first for rule: ", g.ExtRuleString(extrule))
if len(extrule.rhs) == 0 {
loop = addFirst(extrule.lhs, syms.EMPTY) || loop
}
for idx, exts := range extrule.rhs {
for x := range first[exts] {
if x != syms.EMPTY {
loop = addFirst(extrule.lhs, x) || loop
}
}
if !first[exts][syms.EMPTY] {
break
} else if idx == len(extrule.rhs)-1 {
loop = addFirst(extrule.lhs, syms.EMPTY) || loop
}
}
}
}
}
if p.debug {
fmt.Println("\nfirstSet:")
for exts := range first {
fmt.Println(p.ExtSymString(exts), symNames(first[exts]))
}
}
// build follow sets for extended symbols
follow := make(map[ExtSymbol]map[syms.SymbolID]bool)
{
addFollow := func(sym ExtSymbol, symfollow syms.SymbolID) bool {
m, ok := follow[sym]
if !ok {
m = make(map[syms.SymbolID]bool)
follow[sym] = m
}
if _, exists := m[symfollow]; exists {
return false
}
m[symfollow] = true
return true
}
addFollow(p.extRules[0].lhs, syms.EOF)
loop := true
for loop {
loop = false
for i := len(p.extRules) - 1; i >= 0; i-- {
extrule := p.extRules[i]
// fmt.Println("test follow for rule: ", g.ExtRuleString(extrule))
for idx, exts := range extrule.rhs {
if p.Syms.Get(exts.symbolID).IsTerm {
continue
}
if idx == len(extrule.rhs)-1 {
for x := range follow[extrule.lhs] {
loop = addFollow(exts, x) || loop
}
}
for idx2, exts2 := range extrule.rhs[idx+1:] {
// fmt.Println("test follow for pair: ", p.ExtSymString(exts), p.ExtSymString(exts2))
for x := range first[exts2] {
if x != syms.EMPTY {
loop = addFollow(exts, x) || loop
}
}
if !first[exts2][syms.EMPTY] {
break
} else if idx2 == len(extrule.rhs)-1 {
for x := range follow[extrule.lhs] {
loop = addFollow(exts, x) || loop
}
}
}
// fmt.Println("added follow of: ", p.ExtSymString(exts), symNames(follow[exts]))
}
}
}
}
if p.debug {
fmt.Println("\nfollowSet:")
for exts := range follow {
fmt.Println(p.ExtSymString(exts), symNames(follow[exts]))
}
}
// then the action/goto table
p.parsetable = make([]map[syms.SymbolID]Action, len(p.itemSets))
{
for isID, is := range p.itemSets {
m := make(map[syms.SymbolID]Action, len(is.transitions))
for sid, endIsID := range is.transitions {
if p.Syms.Get(sid).IsTerm {
m[sid] = Action{actiontype: Shift, state: endIsID, ruleID: -1}
} else {
m[sid] = Action{actiontype: Goto, state: endIsID, ruleID: -1}
}
}
p.parsetable[isID] = m
}
// Reduce actions:
warnings := make(map[grammar.RuleID]bool)
for _, extrule := range p.extRules {
if len(extrule.rhs) == 0 {
continue
}
lastState := extrule.rhs[len(extrule.rhs)-1].stop
transitions := p.parsetable[lastState]
// fmt.Println("parsetable from rule ", g.ExtRuleString(extrule))
for term := range follow[extrule.lhs] {
act, found := transitions[term]
newact := Action{actiontype: Reduce, state: -1, ruleID: extrule.original}
// fmt.Println("add transition:", lastState, " for term ", p.symbols.name(term))
if found && act != newact {
if !warnings[extrule.original] {
msg := fmt.Sprint("shift/reduce conflict on term: ", p.Syms.Get(term).Name,
"\naction: ", act, "\nnewaction: ", newact,
"\nreduce by rule: ", p.Rules.Get(extrule.original).String(*p.Syms, -1))
log.Printf("Warning:\n%s\n", msg)
warnings[extrule.original] = true
}
// return GrammarConflictError(msg)
} else {
transitions[term] = newact
}
}
}
}
if p.debug {
fmt.Println("\nparsetable:")
for state, m := range p.parsetable {
fmt.Println(state, " -> ")
for sid, a := range m {
fmt.Println("\t", p.Syms.Get(sid).Name, ":", a)
}
}
}
return nil
}