Parser.java 文件源码

/**
 * The ATN with bypass alternatives is expensive to create so we create it
 * lazily.
 *
 * @throws UnsupportedOperationException if the current parser does not
 * implement the {@link #getSerializedATN()} method.
 */
@NotNull
public ATN getATNWithBypassAlts() {
    String serializedAtn = getSerializedATN();
    if (serializedAtn == null) {
        throw new UnsupportedOperationException("The current parser does not support an ATN with bypass alternatives.");
    }

    synchronized (bypassAltsAtnCache) {
        ATN result = bypassAltsAtnCache.get(serializedAtn);
        if (result == null) {
            ATNDeserializationOptions deserializationOptions = new ATNDeserializationOptions();
            deserializationOptions.setGenerateRuleBypassTransitions(true);
            result = new ATNDeserializer(deserializationOptions).deserialize(serializedAtn.toCharArray());
            bypassAltsAtnCache.put(serializedAtn, result);
        }

        return result;
    }
}