diff options
| -rw-r--r-- | driver/parser.go | 25 | ||||
| -rw-r--r-- | grammar/grammar.go | 1 | ||||
| -rw-r--r-- | grammar/parsing_table.go | 29 | ||||
| -rw-r--r-- | spec/grammar.go | 1 |
4 files changed, 20 insertions, 36 deletions
diff --git a/driver/parser.go b/driver/parser.go index 8cd6511..91f364e 100644 --- a/driver/parser.go +++ b/driver/parser.go @@ -185,7 +185,7 @@ ACTION_LOOP: Col: tok.Col, Message: "unexpected token", Token: tok, - ExpectedTerminals: p.expectedTerms(p.top()), + ExpectedTerminals: p.searchLookahead(p.top()), }) ok := p.trapError() @@ -456,28 +456,33 @@ func (p *Parser) SyntaxErrors() []*SyntaxError { return p.synErrs } -func (p *Parser) expectedTerms(state int) []string { +func (p *Parser) searchLookahead(state int) []string { kinds := []string{} - terms := p.gram.ParsingTable.ExpectedTerminals[state] + term2Kind := p.gram.LexicalSpecification.Maleeni.TerminalToKind + kindNames := p.gram.LexicalSpecification.Maleeni.Spec.KindNames aliases := p.gram.LexicalSpecification.Maleeni.KindAliases - for _, tsym := range terms { + termCount := p.gram.ParsingTable.TerminalCount + base := p.top() * termCount + for term := 0; term < termCount; term++ { + if p.gram.ParsingTable.Action[base+term] == 0 { + continue + } + // We don't add the error symbol to the look-ahead symbols because users cannot input the error symbol // intentionally. - if tsym == p.gram.ParsingTable.ErrorSymbol { + if term == p.gram.ParsingTable.ErrorSymbol { continue } - if tsym == p.gram.ParsingTable.EOFSymbol { + if term == p.gram.ParsingTable.EOFSymbol { kinds = append(kinds, "<eof>") continue } - if alias := aliases[tsym]; alias != "" { + if alias := aliases[term]; alias != "" { kinds = append(kinds, alias) } else { - term2Kind := p.gram.LexicalSpecification.Maleeni.TerminalToKind - kindNames := p.gram.LexicalSpecification.Maleeni.Spec.KindNames - kinds = append(kinds, kindNames[term2Kind[tsym]].String()) + kinds = append(kinds, kindNames[term2Kind[term]].String()) } } diff --git a/grammar/grammar.go b/grammar/grammar.go index 1f4f166..efa0f35 100644 --- a/grammar/grammar.go +++ b/grammar/grammar.go @@ -1165,7 +1165,6 @@ func Compile(gram *Grammar, opts ...CompileOption) (*spec.CompiledGrammar, error ErrorSymbol: gram.errorSymbol.num().Int(), ErrorTrapperStates: tab.errorTrapperStates, RecoverProductions: recoverProds, - ExpectedTerminals: tab.expectedTerminals, }, ASTAction: &spec.ASTAction{ Entries: astActEnties, diff --git a/grammar/parsing_table.go b/grammar/parsing_table.go index a82ef60..aa88ad5 100644 --- a/grammar/parsing_table.go +++ b/grammar/parsing_table.go @@ -97,12 +97,11 @@ var ( ) type ParsingTable struct { - actionTable []actionEntry - goToTable []goToEntry - stateCount int - terminalCount int - nonTerminalCount int - expectedTerminals [][]int + actionTable []actionEntry + goToTable []goToEntry + stateCount int + terminalCount int + nonTerminalCount int // errorTrapperStates's index means a state number, and when `errorTrapperStates[stateNum]` is `1`, // the state has an item having the following form. The `α` and `β` can be empty. @@ -158,7 +157,6 @@ func (b *lrTableBuilder) build() (*ParsingTable, error) { stateCount: len(b.automaton.states), terminalCount: b.termCount, nonTerminalCount: b.nonTermCount, - expectedTerminals: make([][]int, len(b.automaton.states)), errorTrapperStates: make([]int, len(b.automaton.states)), InitialState: initialState.num, } @@ -169,12 +167,9 @@ func (b *lrTableBuilder) build() (*ParsingTable, error) { ptab.errorTrapperStates[state.num] = 1 } - eTerms := map[int]struct{}{} - for sym, kID := range state.next { nextState := b.automaton.states[kID] if sym.isTerminal() { - eTerms[sym.num().Int()] = struct{}{} b.writeShiftAction(ptab, state.num, sym, nextState.num) } else { ptab.writeGoTo(state.num, sym, nextState.num) @@ -211,23 +206,9 @@ func (b *lrTableBuilder) build() (*ParsingTable, error) { } for a := range reducibleItem.lookAhead.symbols { - eTerms[a.num().Int()] = struct{}{} b.writeReduceAction(ptab, state.num, a, reducibleProd.num) } } - - ts := make([]int, len(eTerms)) - { - i := 0 - for t := range eTerms { - ts[i] = t - i++ - } - sort.Slice(ts, func(i, j int) bool { - return ts[i] < ts[j] - }) - } - ptab.expectedTerminals[state.num] = ts } return ptab, nil diff --git a/spec/grammar.go b/spec/grammar.go index 42e6dc2..8403308 100644 --- a/spec/grammar.go +++ b/spec/grammar.go @@ -37,7 +37,6 @@ type ParsingTable struct { ErrorSymbol int `json:"error_symbol"` ErrorTrapperStates []int `json:"error_trapper_states"` RecoverProductions []int `json:"recover_productions"` - ExpectedTerminals [][]int `json:"expected_terminals"` } type ASTAction struct { |