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ATN serialized data: remove shifting by 2, remove UUID #17

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Feb 6, 2022
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ATN serialized data: remove shifting by 2, remove UUID #17

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112 changes: 7 additions & 105 deletions src/Atn/ATNDeserializer.php
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Original file line number Diff line number Diff line change
Expand Up @@ -46,38 +46,7 @@

final class ATNDeserializer
{
/**
* This value should never change. Updates following this version are
* reflected as change in the unique ID SERIALIZED_UUID.
*/
public const SERIALIZED_VERSION = 3;

/**
* This is the earliest supported serialized UUID.
* Stick to serialized version for now, we don't need a UUID instance.
*/
private const BASE_SERIALIZED_UUID = 'AADB8D7E-AEEF-4415-AD2B-8204D6CF042E';

/**
* This UUID indicates the serialized ATN contains two sets of IntervalSets,
* where the second set's values are encoded as 32-bit integers to support
* the full Unicode SMP range up to U+10FFFF.
*/
private const ADDED_UNICODE_SMP = '59627784-3BE5-417A-B9EB-8131A7286089';

/**
* This list contains all of the currently supported UUIDs, ordered by when
* the feature first appeared in this branch.
*/
private const SUPPORTED_UUIDS = [
self::BASE_SERIALIZED_UUID,
self::ADDED_UNICODE_SMP,
];

/**
* This is the current serialized UUID.
*/
private const SERIALIZED_UUID = self::ADDED_UNICODE_SMP;
public const SERIALIZED_VERSION = 4;

/** @var ATNDeserializationOptions */
private $deserializationOptions;
Expand All @@ -88,9 +57,6 @@ final class ATNDeserializer
/** @var int */
private $pos = 0;

/** @var string */
private $uuid = '';

/** @var array<int, callable|null>|null */
private $stateFactories;

Expand All @@ -102,38 +68,10 @@ public function __construct(?ATNDeserializationOptions $options = null)
$this->deserializationOptions = $options ?? ATNDeserializationOptions::defaultOptions();
}

/**
* Determines if a particular serialized representation of an ATN supports
* a particular feature, identified by the {@see UUID} used for serializing
* the ATN at the time the feature was first introduced.
*
* @param string $feature The {@see UUID} marking the first time the
* feature was supported in the serialized ATN.
* @param string $actualUuid The {@see UUID} of the actual serialized ATN
* which is currently being deserialized.
*
* @return bool `true` if the `actualUuid` value represents a serialized
* ATN at or after the feature identified by `feature` was
* introduced; otherwise, `false`.
*/
protected function isFeatureSupported(string $feature, string $actualUuid) : bool
{
$featureIndex = \array_search($feature, self::SUPPORTED_UUIDS, true);

if ($featureIndex === false) {
return false;
}

$actualUuidIndex = \array_search($actualUuid, self::SUPPORTED_UUIDS, true);

return $actualUuidIndex >= $featureIndex;
}

public function deserialize(string $data) : ATN
{
$this->reset($data);
$this->checkVersion();
$this->checkUUID();
$atn = $this->readATN();
$this->readStates($atn);
$this->readRules($atn);
Expand All @@ -145,14 +83,10 @@ public function deserialize(string $data) : ATN
return $this->readInt();
});

// Next, if the ATN was serialized with the Unicode SMP feature,
// deserialize sets with 32-bit arguments <= U+10FFFF.

if ($this->isFeatureSupported(self::ADDED_UNICODE_SMP, $this->uuid)) {
$this->readSets($sets, function () {
return $this->readInt32();
});
}
// Next, deserialize sets with 32-bit arguments <= U+10FFFF.
$this->readSets($sets, function () {
return $this->readInt32();
});

$this->readEdges($atn, $sets);
$this->readDecisions($atn);
Expand All @@ -178,10 +112,8 @@ private function reset(string $data) : void
return;
}

$this->data = [StringUtils::codePoint($characters[0])];
for ($i = 1, $length = \count($characters); $i < $length; $i++) {
$code = StringUtils::codePoint($characters[$i]);
$this->data[] = $code > 1 ? $code - 2 : $code + 65533;
for ($i = 0, $length = \count($characters); $i < $length; $i++) {
$this->data[] = StringUtils::codePoint($characters[$i]);
}

$this->pos = 0;
Expand All @@ -201,21 +133,6 @@ private function checkVersion() : void
}
}

private function checkUUID() : void
{
$uuid = $this->readUUID();

if (!\in_array($uuid, self::SUPPORTED_UUIDS, true)) {
throw new \InvalidArgumentException(\sprintf(
'Could not deserialize ATN with UUID: %s (expected %s or a legacy UUID).',
$uuid,
self::SERIALIZED_UUID
));
}

$this->uuid = $uuid;
}

private function readATN() : ATN
{
$grammarType = $this->readInt();
Expand Down Expand Up @@ -739,21 +656,6 @@ private function readInt32() : int
return $low | ($high << 16);
}

private function readUUID() : string
{
$bb = [];
for ($i=0; $i < 8; $i++) {
$int = $this->readInt();
$bb[] = $int & 0xFF;
$bb[] = ($int >> 8) & 0xFF;
}

$bb = \array_reverse($bb);
$hex = \strtoupper(\bin2hex(\implode(\array_map('chr', $bb))));

return \vsprintf('%s%s-%s-%s-%s-%s%s%s', \str_split($hex, 4));
}

/**
* @param array<IntervalSet> $sets
*/
Expand Down