<?php
namespace Code_Snippets\Utils;
/**
* Validates code prior to execution.
*
* @package Code_Snippets
*/
class Validator {
/**
* Code to validate.
*
* @var string
*/
private string $code;
/**
* List of tokens.
*
* @var array<string>
*/
private array $tokens;
/**
* The index of the token currently being examined.
*
* @var int
*/
private int $current;
/**
* The total number of tokens.
*
* @var int
*/
private int $length;
/**
* Array to keep track of the various function, class and interface identifiers which have been defined.
*
* @var array<string, string[]>
*/
private array $defined_identifiers = [];
/**
* Exclude certain tokens from being checked.
*
* @var array<string, string[]>
*/
private array $exceptions = [];
/**
* Identifiers already claimed by other snippets being validated alongside
* this one.
*
* A snippet is validated against everything PHP has declared so far, which
* does not include a snippet that is about to be activated in the same
* batch. Two snippets declaring the same function therefore both passed and
* both activated, and the site fataled on the next request.
*
* @var array<string, string[]>
*/
private array $claimed_identifiers = [];
/**
* Class constructor.
*
* @param string $code Snippet code for parsing.
* @param array<string, string[]> $claimed_identifiers Identifiers already claimed by
* snippets validated alongside this one.
*/
public function __construct( string $code, array $claimed_identifiers = [] ) {
$this->claimed_identifiers = $claimed_identifiers;
$this->code = $code;
$this->tokens = token_get_all( "<?php\n" . $this->code );
$this->length = count( $this->tokens );
$this->current = 0;
}
/**
* Retrieve the identifiers claimed so far, including this snippet's own.
*
* Pass the result to the next Validator in a batch so that two snippets
* cannot both claim the same name.
*
* @return array<string, string[]>
*/
public function get_claimed_identifiers(): array {
return $this->claimed_identifiers;
}
/**
* Determine whether the parser has reached the end of the list of tokens.
*
* @return bool
*/
private function end(): bool {
return $this->current === $this->length;
}
/**
* Retrieve the next token without moving the pointer
*
* @return string|array<string|int>|null The current token if the list has not been expended, null otherwise.
*/
private function peek() {
return $this->end() ? null : $this->tokens[ $this->current ];
}
/**
* Move the pointer to the next token, if there is one.
*
* If the first argument is provided, only move the pointer if the tokens match.
*/
private function next() {
if ( ! $this->end() ) {
++$this->current;
}
}
/**
* Check whether a particular identifier has been used previously.
*
* @param string $type Which type of identifier this is. Supports T_FUNCTION, T_CLASS and T_INTERFACE.
* @param string $identifier The name of the identifier itself.
*
* @return bool true if the identifier is not unique.
*/
private function check_duplicate_identifier( string $type, string $identifier ): bool {
$identifier = strtolower( ltrim( $identifier, '\\' ) );
$namespaced_identifier = 'code_snippets\\' . $identifier;
if ( ! isset( $this->defined_identifiers[ $type ] ) ) {
switch ( $type ) {
case T_FUNCTION:
$defined_functions = get_defined_functions();
$this->defined_identifiers[ T_FUNCTION ] = array_map(
'strtolower',
array_merge( $defined_functions['internal'], $defined_functions['user'] )
);
break;
case T_CLASS:
$this->defined_identifiers[ T_CLASS ] = array_map( 'strtolower', get_declared_classes() );
break;
case T_INTERFACE:
$this->defined_identifiers[ T_INTERFACE ] = array_map( 'strtolower', get_declared_interfaces() );
break;
default:
return false;
}
}
$known = array_merge(
$this->defined_identifiers[ $type ],
$this->claimed_identifiers[ $type ] ?? []
);
$duplicate_identifier = in_array( $identifier, $known, true );
$duplicate_namespaced = in_array( $namespaced_identifier, $known, true );
$exceptions = $this->exceptions[ $type ] ?? [];
$exception_identifier = in_array( $identifier, $exceptions, true );
$exception_namespaced = in_array( $namespaced_identifier, $exceptions, true );
array_unshift( $this->defined_identifiers[ $type ], $identifier );
$this->claimed_identifiers[ $type ][] = $identifier;
return ( $duplicate_identifier && ! $exception_identifier ) || ( $duplicate_namespaced && ! $exception_namespaced );
}
/**
* Validate the given PHP code and return the result.
*
* @return array<string, mixed>|false Array containing message if an error was encountered, false if validation was successful.
*/
public function validate() {
while ( ! $this->end() ) {
$token = $this->peek();
$this->next();
if ( ! is_array( $token ) ) {
continue;
}
// If this is a function or class exists check, then allow this function or class to be defined.
if ( T_STRING === $token[0] && ( 'function_exists' === $token[1] || 'class_exists' === $token[1] ) ) {
$type = 'function_exists' === $token[1] ? T_FUNCTION : T_CLASS;
// Eat tokens until we find the function or class name.
while ( ! $this->end() && T_CONSTANT_ENCAPSED_STRING !== $token[0] ) {
$token = $this->peek();
$this->next();
}
// Add the identifier to the list of exceptions.
$identifier = strtolower( ltrim( trim( $token[1], '\'"' ), '\\' ) );
if ( '' !== $identifier ) {
$this->exceptions[ $type ] = $this->exceptions[ $type ] ?? [];
$this->exceptions[ $type ][] = $identifier;
}
continue;
}
// If we have a double colon, followed by a class, then consume it before the next section.
if ( T_DOUBLE_COLON === $token[0] ) {
$token = $this->peek();
$this->next();
if ( T_CLASS === $token[0] ) {
$this->next();
$token = $this->peek();
}
}
// Only look for class and function declaration tokens.
if ( T_CLASS !== $token[0] && T_FUNCTION !== $token[0] ) {
continue;
}
/**
* Ensure the type of $token is inferred correctly.
*
* @var string|array<string|int> $token
*/
$structure_type = $token[0];
// Continue eating tokens until we find the name of the class or function.
while ( ! $this->end() && T_STRING !== $token[0] &&
( T_FUNCTION !== $structure_type || '(' !== $token ) && ( T_CLASS !== $structure_type || '{' !== $token ) ) {
$token = $this->peek();
$this->next();
}
// If we've eaten all the tokens without discovering a name, then there must be a syntax error, so return appropriately.
if ( $this->end() ) {
return array(
'message' => __( 'Parse error: syntax error, unexpected end of snippet.', 'code-snippets' ),
'line' => $token[2],
);
}
// If the function or class is anonymous, with no name, then no need to check.
if ( ! ( T_FUNCTION === $structure_type && '(' === $token ) && ! ( T_CLASS === $structure_type && '{' === $token ) ) {
// Check whether the name has already been defined.
if ( $this->check_duplicate_identifier( $structure_type, $token[1] ) ) {
switch ( $structure_type ) {
case T_FUNCTION:
/* translators: %s: PHP function name */
$message = __( 'Cannot redeclare function %s.', 'code-snippets' );
break;
case T_CLASS:
/* translators: %s: PHP class name */
$message = __( 'Cannot redeclare class %s.', 'code-snippets' );
break;
case T_INTERFACE:
/* translators: %s: PHP interface name */
$message = __( 'Cannot redeclare interface %s.', 'code-snippets' );
break;
default:
/* translators: %s: PHP identifier name*/
$message = __( 'Cannot redeclare %s.', 'code-snippets' );
}
return array(
'message' => sprintf( $message, $token[1] ),
'line' => $token[2],
);
}
}
// If we have entered into a class, eat tokens until we find the closing brace.
if ( T_CLASS !== $structure_type ) {
continue;
}
// Find the opening brace for the class.
while ( ! $this->end() && '{' !== $token ) {
$token = $this->peek();
$this->next();
}
// Continue traversing the class tokens until we have found the class closing brace.
$depth = 1;
while ( ! $this->end() && $depth > 0 ) {
$token = $this->peek();
if ( '{' === $token ) {
++$depth;
} elseif ( '}' === $token ) {
--$depth;
}
$this->next();
}
// If we did not make it out of the class, then there's a problem.
if ( $depth > 0 ) {
return array(
'message' => __( 'Parse error: syntax error, unexpected end of snippet.', 'code-snippets' ),
'line' => $token[2],
);
}
}
return false;
}
}