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use std::collections::HashMap;
use crate::atn_state::ATNState;
use crate::atn_state::ATNStateRef;
use crate::atn_type::ATNType;
use crate::dfa::ScopeExt;
use crate::interval_set::IntervalSet;
use crate::lexer_action::LexerAction;
use crate::ll1_analyzer::LL1Analyzer;
use crate::parser::ParserNodeType;
use crate::rule_context::EmptyContextType;
use crate::token::{TOKEN_EOF, TOKEN_EPSILON};
use crate::token_factory::CommonTokenFactory;
use crate::transition::RuleTransition;
use std::fmt::{Debug, Formatter};
pub const INVALID_ALT: isize = 0;
/// Augmented Transition Network
///
/// Basically NFA(graph) of states and possible(maybe multiple) transitions on a given particular symbol.
///
/// Public mostly because of implementations reasons. From user side is only useful for advanced error handling
pub struct ATN {
pub decision_to_state: Vec<ATNStateRef>,
pub grammar_type: ATNType,
pub(crate) lexer_actions: Vec<LexerAction>,
pub max_token_type: isize,
pub mode_name_to_start_state: HashMap<String, ATNStateRef>,
pub mode_to_start_state: Vec<ATNStateRef>,
pub rule_to_start_state: Vec<ATNStateRef>,
pub rule_to_stop_state: Vec<ATNStateRef>,
pub rule_to_token_type: Vec<isize>,
pub states: Vec<Box<dyn ATNState>>,
}
impl Debug for ATN {
fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
f.debug_struct("ATN")
.field("grammar_type", &self.grammar_type)
.field("max_token_type", &self.max_token_type)
.field("states count", &self.states.len())
.field("..", &"..")
.finish()
}
}
impl ATN {
crate fn new_atn(grammar_type: ATNType, max_token_type: isize) -> ATN {
ATN {
decision_to_state: Vec::new(),
grammar_type,
lexer_actions: vec![],
max_token_type,
mode_name_to_start_state: HashMap::new(),
mode_to_start_state: Vec::new(),
rule_to_start_state: Vec::new(),
rule_to_stop_state: Vec::new(),
rule_to_token_type: Vec::new(),
states: Vec::new(),
}
}
///Compute the set of valid tokens that can occur starting in `s` and
///staying in same rule. `Token::EPSILON` is in set if we reach end of
///rule.
pub fn next_tokens<'a>(&self, s: &'a dyn ATNState) -> &'a IntervalSet {
s.get_next_tokens_within_rule().get_or_init(|| {
self.next_tokens_in_ctx::<EmptyContextType<'_, CommonTokenFactory>>(s, None)
.modify_with(|r| r.read_only = true)
})
}
/// Compute the set of valid tokens that can occur starting in state `s`.
/// If `ctx` is null, the set of tokens will not include what can follow
/// the rule surrounding `s`. In other words, the set will be
/// restricted to tokens reachable staying within `s`'s rule.
pub fn next_tokens_in_ctx<'a, Ctx: ParserNodeType<'a>>(
&self,
s: &dyn ATNState,
_ctx: Option<&Ctx::Type>,
) -> IntervalSet {
let analyzer = LL1Analyzer::new(self);
analyzer.look::<Ctx>(s, None, _ctx)
}
crate fn add_state(&mut self, state: Box<dyn ATNState>) {
debug_assert_eq!(state.get_state_number(), self.states.len());
self.states.push(state)
}
// fn remove_state(&self, _state: ATNStateRef) { unimplemented!() }
// fn define_decision_state(&self, _s: ATNStateRef) -> isize { unimplemented!() }
pub fn get_decision_state(&self, decision: usize) -> ATNStateRef {
self.decision_to_state[decision]
}
/// Computes the set of input symbols which could follow ATN state number
/// {@code stateNumber} in the specified full {@code context}. This method
/// considers the complete parser context, but does not evaluate semantic
/// predicates (i.e. all predicates encountered during the calculation are
/// assumed true). If a path in the ATN exists from the starting state to the
/// {@link RuleStopState} of the outermost context without matching any
/// symbols, {@link Token#EOF} is added to the returned set.
///
/// <p>If {@code context} is {@code null}, it is treated as {@link ParserRuleContext#EMPTY}.</p>
///
/// Note that this does NOT give you the set of all tokens that could
/// appear at a given token position in the input phrase. In other words,
/// it does not answer:
///
/// "Given a specific partial input phrase, return the set of all tokens
/// that can follow the last token in the input phrase."
///
/// The big difference is that with just the input, the parser could
/// land right in the middle of a lookahead decision. Getting
/// all *possible* tokens given a partial input stream is a separate
/// computation. See https://github.com/antlr/antlr4/issues/1428
///
/// For this function, we are specifying an ATN state and call stack to compute
/// what token(s) can come next and specifically: outside of a lookahead decision.
/// That is what you want for error reporting and recovery upon parse error.
///
/// @param stateNumber the ATN state number
/// @param context the full parse context
/// @return The set of potentially valid input symbols which could follow the
/// specified state in the specified context.
/// Panics if the ATN does not contain a state with
/// number {@code stateNumber}
pub fn get_expected_tokens(
&self,
state_number: isize,
states_stack: impl Iterator<Item = isize>, // _ctx: &Rc<Ctx::Type>,
) -> IntervalSet {
let s = self.states[state_number as usize].as_ref();
let mut following = self.next_tokens(s);
if !following.contains(TOKEN_EPSILON) {
return following.clone();
}
let mut expected = IntervalSet::new();
expected.add_set(&following);
expected.remove_one(TOKEN_EPSILON);
// let mut ctx = Some(Rc::clone(_ctx));
for state in states_stack {
if !following.contains(TOKEN_EPSILON) {
break;
}
let invoking_state = self.states[state as usize].as_ref();
let tr = invoking_state.get_transitions().first().unwrap().as_ref();
let tr = tr.cast::<RuleTransition>();
following = self.next_tokens(self.states[tr.follow_state].as_ref());
expected.add_set(following);
expected.remove_one(TOKEN_EPSILON);
// ctx = c.get_parent_ctx();
}
if following.contains(TOKEN_EPSILON) {
expected.add_one(TOKEN_EOF);
}
expected
}
}