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Preserve backwards compatibility for grammars generated with versions of the tool prior to adding precedence predicates

This commit is contained in:
Sam Harwell 2013-10-10 21:10:11 -05:00
parent b14ca56441
commit 7e3711aca2
1 changed files with 59 additions and 7 deletions
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66
runtime/Java/src/org/antlr/v4/runtime/atn/ATNSimulator.java
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@ -52,12 +52,59 @@ public abstract class ATNSimulator {
SERIALIZED_VERSION = 3;
}
/**
* This is the earliest supported serialized UUID.
*/
private static final UUID BASE_SERIALIZED_UUID;
/**
* This UUID indicates an extension of {@link BASE_SERIALIZED_UUID} for the
* addition of precedence predicates.
*/
private static final UUID ADDED_PRECEDENCE_TRANSITIONS;
/**
* This list contains all of the currently supported UUIDs, ordered by when
* the feature first appeared in this branch.
*/
private static final List<UUID> SUPPORTED_UUIDS;
/**
* This is the current serialized UUID.
*/
public static final UUID SERIALIZED_UUID;
static {
/* WARNING: DO NOT MERGE THIS LINE. If UUIDs differ during a merge,
* resolve the conflict by generating a new ID!
*/
SERIALIZED_UUID = UUID.fromString("33761B2D-78BB-4A43-8B0B-4F5BEE8AACF3");
BASE_SERIALIZED_UUID = UUID.fromString("33761B2D-78BB-4A43-8B0B-4F5BEE8AACF3");
ADDED_PRECEDENCE_TRANSITIONS = UUID.fromString("1DA0C57D-6C06-438A-9B27-10BCB3CE0F61");
SUPPORTED_UUIDS = new ArrayList<UUID>();
SUPPORTED_UUIDS.add(BASE_SERIALIZED_UUID);
SUPPORTED_UUIDS.add(ADDED_PRECEDENCE_TRANSITIONS);
SERIALIZED_UUID = ADDED_PRECEDENCE_TRANSITIONS;
}
/**
* Determines if a particular serialized representation of an ATN supports
* a particular feature, identified by the {@link UUID} used for serializing
* the ATN at the time the feature was first introduced.
*
* @param feature The {@link UUID} marking the first time the feature was
* supported in the serialized ATN.
* @param actualUuid The {@link UUID} of the actual serialized ATN which is
* currently being deserialized.
* @return {@code true} if the {@code actualUuid} value represents a
* serialized ATN at or after the feature identified by {@code feature} was
* introduced; otherwise, {@code false}.
*/
private static boolean isFeatureSupported(UUID feature, UUID actualUuid) {
int featureIndex = SUPPORTED_UUIDS.indexOf(feature);
if (featureIndex < 0) {
return false;
}
return SUPPORTED_UUIDS.indexOf(actualUuid) >= featureIndex;
}
/** Must distinguish between missing edge and edge we know leads nowhere */
@ -134,11 +181,14 @@ public abstract class ATNSimulator {
UUID uuid = toUUID(data, p);
p += 8;
if (!uuid.equals(SERIALIZED_UUID)) {
String reason = String.format(Locale.getDefault(), "Could not deserialize ATN with UUID %s (expected %s).", uuid, SERIALIZED_UUID);
if (!uuid.equals(SERIALIZED_UUID)
&& !uuid.equals(BASE_SERIALIZED_UUID)) {
String reason = String.format(Locale.getDefault(), "Could not deserialize ATN with UUID %s (expected %s or a legacy UUID).", uuid, SERIALIZED_UUID);
throw new UnsupportedOperationException(new InvalidClassException(ATN.class.getName(), reason));
}
boolean supportsPrecedencePredicates = isFeatureSupported(ADDED_PRECEDENCE_TRANSITIONS, uuid);
ATNType grammarType = ATNType.values()[toInt(data[p++])];
int maxTokenType = toInt(data[p++]);
ATN atn = new ATN(grammarType, maxTokenType);
@ -189,10 +239,12 @@ public abstract class ATNSimulator {
((DecisionState)atn.states.get(stateNumber)).nonGreedy = true;
}
int numPrecedenceStates = toInt(data[p++]);
for (int i = 0; i < numPrecedenceStates; i++) {
int stateNumber = toInt(data[p++]);
((RuleStartState)atn.states.get(stateNumber)).isPrecedenceRule = true;
if (supportsPrecedencePredicates) {
int numPrecedenceStates = toInt(data[p++]);
for (int i = 0; i < numPrecedenceStates; i++) {
int stateNumber = toInt(data[p++]);
((RuleStartState)atn.states.get(stateNumber)).isPrecedenceRule = true;
}
}
//