antlr-ng/dist/src/automata/TailEpsilonRemover.js

Next generation ANTLR Tool

var __defProp = Object.defineProperty;
var __name = (target, value) => __defProp(target, "name", { value, configurable: true });
import {
  ATNState,
  BlockEndState,
  EpsilonTransition,
  PlusLoopbackState,
  RuleTransition,
  StarLoopbackState
} from "antlr4ng";
class TailEpsilonRemover {
  constructor(atn) {
    this.atn = atn;
  }
  static {
    __name(this, "TailEpsilonRemover");
  }
  visit(s) {
    this.doVisit(s, /* @__PURE__ */ new Set());
  }
  visitState(p) {
    if (p.constructor.stateType === ATNState.BASIC && p.transitions.length === 1) {
      const transition = p.transitions[0];
      let q = transition.target;
      if (transition instanceof RuleTransition) {
        q = transition.followState;
      }
      if (q.constructor.stateType === ATNState.BASIC) {
        const trans = q.transitions[0];
        if (q.transitions.length === 1 && trans instanceof EpsilonTransition) {
          const r = trans.target;
          if (r instanceof BlockEndState || r instanceof PlusLoopbackState || r instanceof StarLoopbackState) {
            const t = p.transitions[0];
            if (t instanceof RuleTransition) {
              t.followState = r;
            } else {
              t.target = r;
            }
            this.atn.removeState(q);
          }
        }
      }
    }
  }
  doVisit(s, visited) {
    if (visited.has(s.stateNumber)) {
      return;
    }
    visited.add(s.stateNumber);
    this.visitState(s);
    for (const t of s.transitions) {
      this.doVisit(t.target, visited);
    }
  }
}
export {
  TailEpsilonRemover
};