Class: Antlr4::Runtime::LL1Analyzer
- Inherits:
-
Object
- Object
- Antlr4::Runtime::LL1Analyzer
- Defined in:
- lib/antlr4/runtime/ll1_analyzer.rb
Constant Summary collapse
- @@hit_pred =
Token::INVALID_TYPE
Instance Attribute Summary collapse
-
#atn ⇒ Object
readonly
Returns the value of attribute atn.
Instance Method Summary collapse
- #_look(s, stopState, ctx, look, lookBusy, calledRuleStack, seeThruPreds, addEOF) ⇒ Object
- #decision_lookahead(s) ⇒ Object
-
#initialize(atn) ⇒ LL1Analyzer
constructor
A new instance of LL1Analyzer.
- #look(s, stop_state, ctx) ⇒ Object
Constructor Details
#initialize(atn) ⇒ LL1Analyzer
Returns a new instance of LL1Analyzer.
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# File 'lib/antlr4/runtime/ll1_analyzer.rb', line 8 def initialize(atn) @atn = atn end |
Instance Attribute Details
#atn ⇒ Object (readonly)
Returns the value of attribute atn.
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# File 'lib/antlr4/runtime/ll1_analyzer.rb', line 6 def atn @atn end |
Instance Method Details
#_look(s, stopState, ctx, look, lookBusy, calledRuleStack, seeThruPreds, addEOF) ⇒ Object
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# File 'lib/antlr4/runtime/ll1_analyzer.rb', line 38 def _look(s, stopState, ctx, look, lookBusy, calledRuleStack, seeThruPreds, addEOF) # System.out.println("_LOOK("+s.stateNumber+", ctx="+ctx) c = ATNConfig.new c.atn_config1(s, 0, ctx) added = false unless lookBusy.include? c lookBusy.add(c) added = true end return unless added if s == stopState if ctx.nil? look.add(Token::EPSILON) return elsif ctx.empty? && addEOF look.add(Token::EOF) return end end if s.is_a? RuleStopState if ctx.nil? look.add(Token::EPSILON) return elsif ctx.empty? && addEOF look.add(Token::EOF) return end if ctx != EmptyPredictionContext::EMPTY # run thru all possible stack tops in ctx removed = calledRuleStack.get(s.rule_index) begin calledRuleStack.clear(s.rule_index) i = 0 while i < ctx.size return_state = atn.states[ctx.get_return_state(i)] _look(return_state, stopState, ctx.get_parent(i), look, lookBusy, calledRuleStack, seeThruPreds, addEOF) i += 1 end ensure calledRuleStack.set(s.rule_index) if removed end return end end n = s.number_of_transitions i = 0 while i < n t = s.transition(i) if t.is_a? RuleTransition.class if calledRuleStack.get(t.target.rule_index) i += 1 next end new_ctx = SingletonPredictionContext.create(ctx, t.follow_state.state_number) begin calledRuleStack.set(t.target.rule_index) _look(t.target, stopState, new_ctx, look, lookBusy, calledRuleStack, seeThruPreds, addEOF) ensure calledRuleStack.clear(t.target.rule_index) end elsif t.is_a? AbstractPredicateTransition if seeThruPreds _look(t.target, stopState, ctx, look, lookBusy, calledRuleStack, seeThruPreds, addEOF) else look.add(HIT_PRED) end elsif t.epsilon? _look(t.target, stopState, ctx, look, lookBusy, calledRuleStack, seeThruPreds, addEOF) elsif t.is_a? WildcardTransition look.add_all(IntervalSet.of(Token::MIN_USER_TOKEN_TYPE, atn.max_token_type)) else set = t.label unless set.nil? if t.is_a? NotSetTransition set = set.complement(IntervalSet.of(Token::MIN_USER_TOKEN_TYPE, atn.max_token_type)) end look.add_all(set) end end i += 1 end end |
#decision_lookahead(s) ⇒ Object
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# File 'lib/antlr4/runtime/ll1_analyzer.rb', line 12 def decision_lookahead(s) return nil if s.nil? look = [] alt = 0 while alt < s.number_of_transitions look[alt] = new IntervalSet look_busy = Set.new see_thru_preds = false # fail to get lookahead upon pred _look(s.transition(alt).target, nil, EmptyPredictionContext::EMPTY, look[alt], look_busy, Set.new, see_thru_preds, false) # Wipe out lookahead for this alternative if we found nothing # or we had a predicate when we !see_thru_preds look[alt] = nil if look[alt].empty? || look[alt].include?(HIT_PRED) alt += 1 end look end |
#look(s, stop_state, ctx) ⇒ Object
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# File 'lib/antlr4/runtime/ll1_analyzer.rb', line 30 def look(s, stop_state, ctx) r = IntervalSet.new see_thru_preds = true # ignore preds get all lookahead look_context = !ctx.nil? ? PredictionContextUtils.from_rule_context(s.atn, ctx) : nil _look(s, stop_state, look_context, r, Set.new, BitSet.new, see_thru_preds, true) r end |