ParserATNSimulator.java 文件源码

/**
 * Add state {@code D} to the DFA if it is not already present, and return
 * the actual instance stored in the DFA. If a state equivalent to {@code D}
 * is already in the DFA, the existing state is returned. Otherwise this
 * method returns {@code D} after adding it to the DFA.
 *
 * <p>If {@code D} is {@link #ERROR}, this method returns {@link #ERROR} and
 * does not change the DFA.</p>
 *
 * @param dfa The dfa
 * @param D The DFA state to add
 * @return The state stored in the DFA. This will be either the existing
 * state if {@code D} is already in the DFA, or {@code D} itself if the
 * state was not already present.
 */
@NotNull
protected DFAState addDFAState(@NotNull DFA dfa, @NotNull DFAState D) {
    if (D == ERROR) {
        return D;
    }

    synchronized (dfa.states) {
        DFAState existing = dfa.states.get(D);
        if ( existing!=null ) return existing;

        D.stateNumber = dfa.states.size();
        if (!D.configs.isReadonly()) {
            D.configs.optimizeConfigs(this);
            D.configs.setReadonly(true);
        }
        dfa.states.put(D, D);
        if ( debug ) System.out.println("adding new DFA state: "+D);
        return D;
    }
}