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jrfnl committed Apr 30, 2024
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393 changes: 393 additions & 0 deletions PHPCSUtils/Utils/TypeString.php
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<?php
/**
* PHPCSUtils, utility functions and classes for PHP_CodeSniffer sniff developers.
*
* @package PHPCSUtils
* @copyright 2019-2024 PHPCSUtils Contributors
* @license https://opensource.org/licenses/LGPL-3.0 LGPL3
* @link https://github.com/PHPCSStandards/PHPCSUtils
*/

namespace PHPCSUtils\Utils;

/**
* Utility functions for use when examining type strings.
*
* The methods in this class are intended to be used with type strings as returned by:
* - [BC]File::getMethodParameters()['type_hint']
* - [BC]File::getMethodProperties()['return_type']
* - [BC]File::getMemberProperties()['type']
* - Constants::getProperties()['type']
* - FunctionDeclarations::getParameters()['type_hint']
* - FunctionDeclarations::getProperties()['return_type']
* - Variables::getMemberProperties()['type']
*
* Notes:
* - Type strings as retrieved from the above listed sources will not contain any whitespace,
* so the methods in this class have limited or no handling for surrounding or internal whitespace.
* - The behaviour with type strings retrieved by other means, or non-type strings, is undefined.
* :warning: Using these methods with type strings retrieved from docblocks is **strongly discouraged**.
* - The `is*()` methods will **not** check if the type string provided is **_valid_**, as doing so would inhibit
* what sniffs can flag.
* The `is*()` methods will only look at the _form_ of the type string to determine if it _could_ be valid
* for a certain type.
* - Use the {@see \PHPCSUtils\Utils\NamingConventions::isValidIdentifierName()} method if additional validity
* checks are needed on the individual "types" seen in a type string.
* - And, if needed, use token walking on the tokens of the type to determine whether a type string actually
* complies with the type rules as set by PHP.
*
* @see \PHPCSUtils\BackCompat\BCFile::getMethodParameters()
* @see \PHPCSUtils\BackCompat\BCFile::getMethodProperties()
* @see \PHPCSUtils\BackCompat\BCFile::getMemberProperties()
* @see \PHPCSUtils\Utils\Constants::getProperties()
* @see \PHPCSUtils\Utils\FunctionDeclarations::getParameters()
* @see \PHPCSUtils\Utils\FunctionDeclarations::getProperties()
* @see \PHPCSUtils\Utils\Variables::getMemberProperties()
*
* @since 1.1.0
*/
final class TypeString
{

/**
* Regex to filter out some matches for invalid "DNF-lookalike" types.
*
* A type string should **not** match against this regex to be considered potentially valid.
*
* @internal
*
* @since 1.1.0
*
* @var string
*/
const INVALID_DNF_REGEX = '`(?:
[()|]\s*& # Make sure that a & is always preceeded by something different than (, ) or |.
|
&\s*[()|] # Make sure that a & is always followed by something different than (, ) or |.
|
\S+\s*[^|\s]\s*\( # Make sure that a ( not at the start of the type string is always preceeded by something + |.
|
\)\s*[^|\s]\s*\S+ # Make sure that a ) not at the end of the type string is always followed by | + something.
)`x';

/**
* A list of all keyword based types in PHP.
*
* The names are listed in lowercase as type names in PHP are case-insensitive
* and comparisons against this list should therefore always be done in a case-insensitive manner.
*
* @since 1.1.0
*
* @var array<string, string>
*/
private static $keywordTypes = [
'array' => 'array',
'bool' => 'bool',
'callable' => 'callable',
'false' => 'false',
'float' => 'float',
'int' => 'int',
'iterable' => 'iterable',
'mixed' => 'mixed',
'never' => 'never',
'null' => 'null',
'object' => 'object',
'parent' => 'parent',
'self' => 'self',
'static' => 'static',
'string' => 'string',
'true' => 'true',
'void' => 'void',
];

/**
* Retrieve a list of all PHP native keyword types.
*
* @since 1.1.0
*
* @return array<string, string> Key and value both contain the type name in lowercase.
*/
public static function getKeywordTypes()
{
return self::$keywordTypes;
}

/**
* Check if a singular type is a PHP native keyword based type.
*
* @since 1.1.0
*
* @param string $type The singular type.
*
* @return bool
*/
public static function isKeyword($type)
{
if (\is_string($type) === false) {
return false;
}

$typeLC = \strtolower(\trim($type));
return isset(self::$keywordTypes[$typeLC]);
}

/**
* Normalize the case for a single type.
*
* - Types which are recognized PHP "keyword" types will be returned in lowercase.
* - Class/Interface/Enum names will be returned in their original case.
*
* @since 1.1.0
*
* @param string $type Type to normalize the case for.
*
* @return string The case-normalized type or an empty string if the input was invalid.
*/
public static function normalizeCase($type)
{
if (\is_string($type) === false) {
return '';
}

if (self::isKeyword($type)) {
return \strtolower($type);
}

return $type;
}

/**
* Check if a type string represents a plain, singular type.
*
* Note: Nullable types are not considered plain, singular types for the purposes of this method.
*
* @since 1.1.0
*
* @param string $typeString Type string.
*
* @return bool
*/
public static function isSingular($typeString)
{
if (\is_string($typeString) === false) {
return false;
}

$typeString = \trim($typeString);

return empty($typeString) === false
&& \strpos($typeString, '?') === false
&& \strpos($typeString, '|') === false
&& \strpos($typeString, '&') === false
&& \strpos($typeString, '(') === false
&& \strpos($typeString, ')') === false;
}

/**
* Check if a type string represents a nullable type.
*
* A nullable type in the context of this method is a type which
* - starts with the nullable operator and has something after it which is being made nullable;
* - or contains `null` as part of a union or DNF type.
*
* A stand-alone `null` type is not considered a nullable type, but a singular type.
*
* @since 1.1.0
*
* @param string $typeString Type string.
*
* @return bool
*/
public static function isNullable($typeString)
{
if (\is_string($typeString) === false) {
return false;
}

$typeString = \trim($typeString);
if (empty($typeString) === true) {
return false;
}

// Check for plain nullable type with something which is being made nullable.
if (\preg_match('`^\?\s*[^|&()?\s]+`', $typeString) === 1) {
return true;
}

// Check for nullable union type.
$matched = \preg_match(
'`(?<before>^|[^|&(?\s]+\s*\|)\s*null\s*(?<after>\|\s*[^|&)?\s]+|$)`i',
$typeString,
$matches
);
return ($matched === 1
&& (empty($matches['before']) === false || empty($matches['after']) === false));
}

/**
* Check if a type string represents a pure union type.
*
* Note: DNF types are not considered union types for the purpose of this method.
*
* @since 1.1.0
*
* @param string $typeString Type string.
*
* @return bool
*/
public static function isUnion($typeString)
{
return \is_string($typeString)
&& \strpos($typeString, '?') === false
&& \strpos($typeString, '|') !== false
&& \strpos($typeString, '&') === false
&& \strpos($typeString, '(') === false
&& \strpos($typeString, ')') === false
// Make sure there is always something before and after each |.
&& \preg_match('`^[^|&()?\s]+(\s*\|\s*[^|&()?\s]+)+$`', $typeString) === 1;
}

/**
* Check if a type string represents a pure intersection type.
*
* Note: DNF types are not considered intersection types for the purpose of this method.
*
* @since 1.1.0
*
* @param string $typeString Type string.
*
* @return bool
*/
public static function isIntersection($typeString)
{
return \is_string($typeString)
&& \strpos($typeString, '?') === false
&& \strpos($typeString, '|') === false
&& \strpos($typeString, '&') !== false
&& \strpos($typeString, '(') === false
&& \strpos($typeString, ')') === false
// Make sure there is always something before and after each &.
&& \preg_match('`^[^|&()?\s]+(\s*&\s*[^|&()?\s]+)+$`', $typeString) === 1;
}

/**
* Check if a type string represents a disjunctive normal form (DNF) type.
*
* This check for a strict
*
* @since 1.1.0
*
* @param string $typeString Type string.
*
* @return bool
*/
public static function isDNF($typeString)
{
return \is_string($typeString)
&& \strpos($typeString, '?') === false
&& \strpos($typeString, '|') !== false
&& \strpos($typeString, '&') !== false
&& \strpos($typeString, '(') !== false
&& \strpos($typeString, ')') !== false
// Now make sure that it is not a definitely invalid format.
&& \preg_match(self::INVALID_DNF_REGEX, $typeString) !== 1;
}

/**
* Split a type string to its individual types and optionally normalize the case of the types.
*
* @since 1.1.0
*
* @param string $typeString Type to split.
* @param bool $normalize Whether or not to normalize the case of types.
* Defaults to true.
*
* @return array<string> List containing all seen types in the order they were encountered.
*/
public static function toArray($typeString, $normalize = true)
{
if (\is_string($typeString) === false || \trim($typeString) === '') {
return [];
}

$addNull = false;
if ($typeString[0] === '?') {
$addNull = true;
$typeString = \substr($typeString, 1);
}

$typeString = \preg_replace('`\s+`', '', $typeString);
$types = \preg_split('`[|&()]+`', $typeString, -1, \PREG_SPLIT_NO_EMPTY);

// Normalize the types.
if ($normalize === true) {
$types = \array_map([__CLASS__, 'normalizeCase'], $types);
}

if ($addNull === true) {
\array_unshift($types, 'null');
}

return $types;
}

/**
* Split a type string to the unique types included and optionally normalize the case of the types.
*
* @since 1.1.0
*
* @param string $typeString Type to split.
* @param bool $normalize Whether or not to normalize the case of types.
* Defaults to true.
*
* @return array<string, string> Associative array with the unique types as both the key as well as the value.
*/
public static function toArrayUnique($typeString, $normalize = true)
{
$types = self::toArray($typeString, $normalize);
return \array_combine($types, $types);
}

/**
* Filter a list of types down to only the keyword based types.
*
* @since 1.1.0
*
* @param array<int|string, string> $types Array of types.
* Typically, this is an array as retrieved from the
* {@see TypeString::toArray()} method or the
* {@see TypeString::toArrayUnique()} method.
*
* @return array<int|string, string> Array with only the PHP native keyword based types.
* The result may be an empty array if the input array didn't contain
* any keyword based types or if the input was invalid.
*/
public static function filterKeywordTypes(array $types)
{
return \array_filter($types, [__CLASS__, 'isKeyword']);
}

/**
* Filter a list of types down to only the OO name based types.
*
* @since 1.1.0
*
* @param array<int|string, string> $types Array of types.
* Typically, this is an array as retrieved from the
* {@see TypeString::toArray()} method or the
* {@see TypeString::toArrayUnique()} method.
*
* @return array<int|string, string> Array with only the OO name based types.
* The result may be an empty array if the input array didn't contain
* any OO name based types or if the input was invalid.
*/
public static function filterOOTypes(array $types)
{
return \array_filter(
$types,
static function ($type) {
return \is_string($type) === true && self::isKeyword($type) === false;
}
);
}
}
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