JsonApiSpec.php

<?php

namespace Drupal\jsonapi;


/**
 * Defines constants used for compliance with the JSON:API specification.
 *
 * @internal JSON:API maintains no PHP API since its API is the HTTP API. This
 *   class may change at any time and this will break any dependencies on it.
 *
 * @see https://www.drupal.org/project/drupal/issues/3032787
 * @see jsonapi.api.php
 *
 * @see http://jsonapi.org/format
 */
class JsonApiSpec {
    
    /**
     * The minimum supported specification version.
     *
     * @see http://jsonapi.org/format/#document-jsonapi-object
     */
    const SUPPORTED_SPECIFICATION_VERSION = '1.0';
    
    /**
     * The URI of the supported specification document.
     */
    const SUPPORTED_SPECIFICATION_PERMALINK = 'http://jsonapi.org/format/1.0/';
    
    /**
     * Member name: globally allowed characters.
     *
     * U+0080 and above (non-ASCII Unicode characters) are allowed, but are not
     * URL-safe. It is RECOMMENDED to not use them.
     *
     * A character class, for use in regular expressions.
     *
     * @see http://jsonapi.org/format/#document-member-names-allowed-characters
     * @see http://php.net/manual/en/regexp.reference.character-classes.php
     */
    const MEMBER_NAME_GLOBALLY_ALLOWED_CHARACTER_CLASS = '[a-zA-Z0-9\\x{80}-\\x{10FFFF}]';
    
    /**
     * Member name: allowed characters except as the first or last character.
     *
     * Space (U+0020) is allowed, but is not URL-safe. It is RECOMMENDED to not
     * use it.
     *
     * A character class, for use in regular expressions.
     *
     * @see http://jsonapi.org/format/#document-member-names-allowed-characters
     * @see http://php.net/manual/en/regexp.reference.character-classes.php
     */
    const MEMBER_NAME_INNER_ALLOWED_CHARACTERS = "[a-zA-Z0-9\\x{80}-\\x{10FFFF}\\-_ ]";
    
    /**
     * Checks whether the given member name is valid.
     *
     * Requirements:
     * - it MUST contain at least one character.
     * - it MUST contain only the allowed characters
     * - it MUST start and end with a "globally allowed character"
     *
     * @param string $member_name
     *   A member name to validate.
     *
     * @return bool
     *   Whether the given member name is in compliance with the JSON:API
     *   specification.
     *
     * @see http://jsonapi.org/format/#document-member-names
     */
    public static function isValidMemberName($member_name) {
        // @todo When D8 requires PHP >=5.6, move to a MEMBER_NAME_REGEXP constant.
        static $regexp;
        // @codingStandardsIgnoreStart
        if (!isset($regexp)) {
            $regexp = '/^' . self::MEMBER_NAME_GLOBALLY_ALLOWED_CHARACTER_CLASS . '{1}' . '(' . self::MEMBER_NAME_INNER_ALLOWED_CHARACTERS . '*' . self::MEMBER_NAME_GLOBALLY_ALLOWED_CHARACTER_CLASS . '{1}' . ')?' . '$/u';
        }
        // @codingStandardsIgnoreEnd
        return preg_match($regexp, $member_name) === 1;
    }
    
    /**
     * The reserved (official) query parameters.
     *
     * @todo When D8 requires PHP >= 5.6, convert to an array.
     */
    const RESERVED_QUERY_PARAMETERS = 'filter|sort|page|fields|include';
    
    /**
     * The query parameter for providing a version (revision) value.
     *
     * @var string
     */
    const VERSION_QUERY_PARAMETER = 'resourceVersion';
    
    /**
     * Gets the reserved (official) JSON:API query parameters.
     *
     * @return string[]
     *   Gets the query parameters reserved by the specification.
     */
    public static function getReservedQueryParameters() {
        return explode('|', static::RESERVED_QUERY_PARAMETERS);
    }
    
    /**
     * Checks whether the given custom query parameter name is valid.
     *
     * A custom query parameter name must be a valid member name, with one
     * additional requirement: it MUST contain at least one non a-z character.
     *
     * Requirements:
     * - it MUST contain at least one character.
     * - it MUST contain only the allowed characters
     * - it MUST start and end with a "globally allowed character"
     * - it MUST contain at least none a-z (U+0061 to U+007A) character
     *
     * It is RECOMMENDED that a hyphen (U+002D), underscore (U+005F) or capital
     * letter is used (i.e. camelCasing).
     *
     * @param string $custom_query_parameter_name
     *   A custom query parameter name to validate.
     *
     * @return bool
     *   Whether the given query parameter is in compliane with the JSON:API
     *   specification.
     *
     * @see http://jsonapi.org/format/#query-parameters
     */
    public static function isValidCustomQueryParameter($custom_query_parameter_name) {
        return static::isValidMemberName($custom_query_parameter_name) && preg_match('/[^a-z]/u', $custom_query_parameter_name) === 1;
    }

}