text: /*
   * Copyright 2017 Google Inc.
   *
   * Use of this source code is governed by a BSD-style license that can be
   * found in the LICENSE file.
   */
  #ifndef SKSL_NFA
  #  define SKSL_NFA
  #  include "src/sksl/lex/NFAState.h"
  #  include "src/sksl/lex/RegexNode.h"
  /**
   * A nondeterministic finite automaton for matching regular expressions. The NFA is initialized with
   * a number of regular expressions, and then matches a string against all of them simultaneously.
   */
  struct NFA
  {
      /**
       * Adds a new regular expression to the set of expressions matched by this automaton, returning
       * its index.
       */
    int addRegex(const RegexNode& regex)
    {
      std::vector<int> accept;
          // we reserve token 0 for END_OF_FILE, so this starts at 1
      accept.push_back(this->addState(NFAState(++fRegexCount)));
      std::vector<int> startStates = regex.createStates(this, accept);
      fStartStates.insert(fStartStates.end(), startStates.begin(), startStates.end());
      return fStartStates.size() - 1;
    }
      /**
       * Adds a new state to the NFA, returning its index.
       */
    int addState(NFAState s)
    {
      fStates.push_back(std::move(s));
      return fStates.size() - 1;
    }
      /**
       * Matches a string against all of the regexes added to this NFA. Returns the index of the first
       * (in addRegex order) matching expression, or -1 if no match. This is relatively slow and used
       * only for debugging purposes; the NFA should be converted to a DFA before actual use.
       */
    int match(std::string s) const;
    int fRegexCount = 0;
    std::vector<NFAState> fStates;
    std::vector<int> fStartStates;
  };
  #endif
  