====== PHP RFC: Followup Improvements for ext/uri ======
  * Version: 0.1
  * Date: 2025-10-17
  * Author: Máté Kocsis, kocsismate@php.net
  * Status: Under Discussion
  * Target version: next minor version (PHP 8.6)
  * Implementation: https://github.com/kocsismate/php-src/pull/9

===== Introduction =====

This RFC proposes various follow-up improvements to the [[rfc:url_parsing_api|URL Parsing API RFC]], extending the ''Uri\Rfc3986\Uri'' and ''Uri\WhatWg\Url'' classes with additional capabilities that were requested during the discussion phase of the original RFC. These capabilities were deemed not to be essential from the get-go, therefore they were postponed in order not to increase scope even further.

===== Proposal =====

The following new functionality is introduced in this proposal:

  - [[#uri_building|URI Building]]
  - [[#query_parameter_manipulation|Query Parameter Manipulation]]
  - [[#accessing_path_segments_as_an_array|Accessing Path Segments as an Array]]
  - [[#host_type_detection|Host Type Detection]]
  - [[#uri_type_detection|URI Type Detection]]
  - [[#percent-encoding_and_decoding_support|Percent-Encoding and Decoding Support]]

Each feature proposed is voted separately and requires a 2/3 majority.

==== URI Building ====

Currently, only **already existing (and validated)** URIs can be manipulated via [[https://wiki.php.net/rfc/url_parsing_api#component_modification|wither methods]]. These calls always create a new instance so that immutability of URIs is preserved. Even though this behavior has plenty of advantages, there's at least one disadvantage: instance creation has a performance overhead. This is especially problematic if a lot of URI components have to be modified in the same time, because a lot of objects are "wasted" through intermediate instantiations.

<code php>
$uri1 = Uri\Rfc3986\Uri::parse("http://example.com");

$uri2 = $uri1
    ->withScheme("https")
    ->withHost("example.net")
    ->withPath("/foo/bar");                // This creates 3 objects altogether!
</code>

Besides its suboptimal performance, another drawback of the current wither-based solution is that URI creation from the scratch is currently not possible: one always has to create a valid URI first. The empty string is a valid RFC 3986 URI, that's why it may seem a good candidate for an initial URI for URI building, but unfortunately, it's not valid for WHATWG URL. And anyway, the success of some transformations depend on the current state (which is a form of temporal coupling):

<code php>
$uri1 = Uri\Rfc3986\Uri::parse("");

$uri2 = $uri1
    ->withScheme("https")
    ->withUserInfo("user:pass")            // throws Uri\InvalidUriException: Cannot set a userinfo without having a host
    ->withHost("example.com");

$uri2 = $uri1
    ->withScheme("https")
    ->withHost("example.com")
    ->withUserInfo("user:pass")            // No exception is thrown
</code>

In order to provide a more ergonomic and efficient solution for URI building, a fluent API is proposed that implements the [[https://refactoring.guru/design-patterns/builder|Builder pattern]].

<code php>
$uriBuilder = new Uri\Rfc3986\UriBuilder()
    ->setScheme("https")
    ->setUserInfo("user:pass")
    ->setHost("example.com")
    ->setPort(8080)
    ->setPath("/foo/bar")
    ->setQuery("a=1&b=2"])
    ->setQueryParams(Uri\Rfc3986\UriQueryParams::fromArray(["a" => 1, "b" => 2]) // Has the same effect as the setQuery() call above
    ->setFragment("section1")

$uri = $uriBuilder->build();               // URI instance creation is only done at this point

echo $uri->toRawString();                  // https://user:pass@example.com:8080/foo/bar?a=1&b=2#section1
</code>

The same works for WHATWG URL:

<code php>
$urlBuilder = new Uri\WhatWg\UrlBuilder()
    ->setScheme("https")
    ->setUsername("user")
    ->setPassword("pass")
    ->setHost("example.com")
    ->setPort(8080)
    ->setPath("/foo/bar")
    ->setQuery("a=1&b=2"])
    ->setQueryParams(Uri\WhatWg\UrlQueryParams::fromArray(["a" => 1, "b" => 2]) // Has the same effect as the setQuery() call above
    ->setFragment("section1")

$url = $urlBuilder->build();               // URL instance creation is only done at this point

echo $url->toAsciiString;                  // https://user:pass@example.com:8080/foo/bar?a=1&b=2#section1
</code>

When a Builder instance is not instantiated by ourselves or a trusted party, one cannot be sure whether it already has any components set. Therefore, it's highly recommended to clear the instance state before usage:

<code php>
function buildUri(Uri\Rfc3986\UriBuilder $builder): void
{
    // Was there any component set before?

    $builder->clear();

    // Further usage is safe now...
}

function buildUrl(Uri\WhatWg\UrlBuilder $builder): void
{
    // Was there any component set before?

    $builder->clear();

    // Further usage is safe now...
}
</code>

The ''clear()'' method also comes handy when the same Builder instance is reused to instantiate multiple URIs/URLs in a row.

The complete class signatures to be added are the following:

<code php>
namespace Uri\Rfc3986 {
    final class UriBuilder
    {
        public function __construct() {}

        public function clear(): static {}

        /**
         * @throws Uri\InvalidUriException
         */
        public function setScheme(?string $scheme): static {}

        /**
         * @throws Uri\InvalidUriException
         */
        public function setUserInfo(#[\SensitiveParameter] ?string $userInfo): static {}

        /**
         * @throws Uri\InvalidUriException
         */
        public function setHost(?string $host): static {}

        /**
         * @throws Uri\InvalidUriException
         */
        public function setPath(string $path): static {}

        /**
         * @throws Uri\InvalidUriException
         */
        public function setPathSegments(array $segments): static {}

        /**
         * @throws Uri\InvalidUriException
         */
        public function setQuery(?string $query): static {}

        /**
         * @throws Uri\InvalidUriException
         */
        public function setQueryParams(\Uri\Rfc3986\UriQueryParams $queryParams): static {}

        /**
         * @throws Uri\InvalidUriException
         */
        public function setFragment(?string $fragment): static {}

        /**
         * @throws Uri\InvalidUriException
         */
        public function build(?\Uri\Rfc3986\Uri $baseUrl = null): \Uri\Rfc3986\Uri {}
    }
}
</code>

<code php>
namespace Uri\WhatWg {
    final class UrlBuilder
    {
        public function __construct() {}

        public function clear(): static {}

        /**
         * @throws Uri\WhatWg\InvalidUrlException
         */
        public function setScheme(?string $scheme): static {}

        /**
         * @throws Uri\WhatWg\InvalidUrlException
         */
        public function setUsername(?string $username): static {}

        /**
         * @throws Uri\WhatWg\InvalidUrlException
         */
        public function setPassword(#[\SensitiveParameter] ?string $password): static {}

        /**
         * @throws Uri\WhatWg\InvalidUrlException
         */
        public function setHost(?string $host): static {}

        /**
         * @throws Uri\WhatWg\InvalidUrlException
         */
        public function setPath(string $path): static {}

        /**
         * @throws Uri\WhatWg\InvalidUrlException
         */
        public function setPathSegments(array $segments): static {}

        /**
         * @throws Uri\WhatWg\InvalidUrlException
         */
        public function setQuery(?string $query): static {}

        /**
         * @throws Uri\WhatWg\InvalidUrlException
         */
        public function setQueryParams(\Uri\WhatWg\UrlQueryParams $queryParams): static {}

        /**
         * @throws Uri\WhatWg\InvalidUrlException
         */
        public function setFragment(?string $fragment): static {}

        /**
         * @param array $errors
         * @throws Uri\WhatWg\InvalidUrlException
         */
        public function build(?\Uri\WhatWg\Url $baseUrl = null, &$errors = null): \Uri\WhatWg\Url {}
    }
}
</code>

The builder objects would perform validation in two places:

- **Validation of pure component syntax**: The individual setter methods would immediately validate if the input is syntactically correct. For example, the scheme component cannot contain percent-encoded octets, therefore the ''setScheme()'' method would throw whenever a "%" character is encountered.
- **Validation of global state**: There are a few validation rules that depend on the "global state". For example, RFC 3986 requires the host component to be present when the userinfo is set. Any such validations would be delayed until the ''build()'' method call to avoid the problem with temporal coupling that was mentioned in the beginning of the section.

An example for component syntax validation:

<code php>
$uriBuilder = new Uri\Rfc3986\UriBuilder()
    ->setScheme("http%80");                // Throws a Uri\InvalidUriException because the scheme is not well formed
</code>

An example for validation of the global state:

<code php>
$uriBuilder = new Uri\Rfc3986\UriBuilder()
    ->setScheme("https")
    ->setUserInfo("user:pass");            // Doesn't throw an exception yet

$uri = $uriBuilder->build();               // Throws an Uri\InvalidUriException because the host is not present, but the userinfo is
</code>

=== Design considerations ===

== Builder design pattern ==

Why is a complex Builder pattern based approach is proposed instead of a much simpler [[https://refactoring.guru/design-patterns/factory-method|Factory Method]] based one? The factory method could be as simple as the following:

<code php>
namespace Uri\Rfc3986 {
    final readonly class Uri
    {
        ...

        public static function fromComponents(
            ?string $scheme = null, ?string $host = null, string $path = "",
            ?string $userInfo = null, ?string $queryString = null, ?string $fragment = null
        ) {}

        ...
    }
}

namespace Uri\WhatWg {
    final readonly class Url
    {
        ...

        public static function fromComponents(
            string $scheme, ?string $host = "", string $path = "",
            ?string $username = null, ?string $password = null,
            ?string $queryString = null, ?string $fragment = null
        ) {}

        ...
    }
}
</code>

The current RFC proposes the Builder pattern based approach because of its flexibility: it makes it possible to add more convenience methods in the future. Actually, the ''setQueryParams()'' method that expects a Query parameter list object instead of the query string representation is already one.

== Dedicated classes ==

This RFC proposes a dedicated Builder class for both RFC 3986 and WHATWG URL, instead of a single, unified implementation with 2 ''build()'' methods (e.g. ''buildUri()'' and ''buildUrl()''). This decision has the following reasons:

  * The two specifications don't recognize the same components. RFC 3986 has the userinfo component, while WHATWG URL has a separate ''username'' and ''password'' component instead. Even though these incompatibilities are probably possible to workaround, the position of this RFC is that it's better not to try to maintain compatibility artificially.
  * RFC 3986 only requires the ''path'' component to be present (that's why the empty string is a valid RFC 3986 URI), while WHATWG URL mandates the presence of the ''scheme'' component too. This distinction is visible from the proposed signatures: while the ''Uri\Rfc3986\UriBuilder::setScheme()'' method accepts a ''string'' or ''null'', ''Uri\WhatWg\UrlBuilder::setScheme()'' only accepts a ''string'' parameter. The same distinction is already present in the ''Uri\Rfc3986\Uri::withScheme()'' and the ''Uri\WhatWg\Url::withScheme()'' methods.
  * Setter methods validate the input based on the rules of the specification they implement. For example, RFC 3986 URIs cannot contain Unicode characters, so all setters fail when such a character is passed to them. On the other hand, WHATWG URL can handle Unicode characters, and setters won't fail when they encounter one. If a single, unified Builder class was proposed, performing validations early during the setter calls wouldn't be possible, only during the ''build*()'' method calls. According to the proposal, this would lead to a counterintuitive behavior because of the delayed feedback loop.

== Mutability ==

The proposed classes are mutable in order to avoid the performance overhead that cloning before each modification (thus an immutable behavior) would cause. If it turns out that the performance overhead is possible to optimize away, then this design decision can be reevaluated.

== Setter naming convention ==

Setter methods of the ''UriBuilder'' and ''UrlBuilder'' classes follow the naming convention which is already widespread among internal functions: they use a ''set'' prefix, e.g. ''setScheme()'', ''setHost()''. The current RFC rejects the usage of any other naming convention, most notably the omission of the ''set'' prefix (e.g. ''scheme()'', ''host()'') due to the following reasons:

  * The ''set'' prefix adds additional context about the intended behavior: all proposed setters completely overwrite the related component. E.g. ''setQuery()'' and ''setQueryParams()'' neither prepend nor append their input to the existing query string, but they both overwrite the whole component. If ''set'' was omitted from the method name, then this additional context was completely missing, and people could have even less idea about what was going to happen when they use these methods.
  * Using the ''set'' prefix for the setters would allow the addition of other convenience methods in the future more naturally: e.g. ''appendQueryParams()'', ''appendPathSegments()'' etc.

=== Voting ===

<doodle title="Add URI building support as outlined in the RFC?" voteType="single" closed="true" closeon="2025-01-01T15:30:00Z">
   * Yes
   * No
   * Abstain
</doodle>

==== Query Parameter Manipulation ====

Query parameter manipulation is an integral part of URI handling. WHATWG URL even dedicates a separate section for the [[https://url.spec.whatwg.org/#interface-urlsearchparams|URLSearchParams]] class that implements advanced query parameter handling. Unfortunately, RFC 3986 doesn't have any such capability, so ultimately, both proposed classes closely follow the  design of the WHATWG URL specification.

Therefore, the following classes and methods are proposed for addition:

<code php>
namespace Uri\Rfc3986 {
    final class UriQueryParams implements \Countable
    {
        public static function parseRfc3986(string $queryString): ?\Uri\Rfc3986\UriQueryParams {}
    
        public static function parseFormData(string $queryString): \Uri\Rfc3986\UriQueryParams {}

        public static function fromArray(array $queryParams): \Uri\Rfc3986\UriQueryParams {}
        
        public function __construct() {}

        public function append(string $name, mixed $value): static {}

        public function delete(string $name): static {}
        
        public function deleteValue(string $name, mixed $value): static {}

        public function has(string $name): bool {}
        
        public function hasValue(string $name, mixed $value): bool {}

        public function getFirst(string $name): ?string {}

        public function getLast(string $name): ?string {}
        
        public function getAll(?string $name = null): array {}
        
        public function count(): int {}

        public function set(string $name, mixed $value): static {}

        public function sort(): static {}
        
        public function toRfc3986String(): string {}
        
        public function toFormDataString(): string {}

        public function __serialize(): array {}

        public function __unserialize(array $data): void {}

        public function __debugInfo(): array {}
    }
</code>

<code php>
    final readonly class Uri
    {
        ...

        public function getRawQueryParams(): ?\Uri\Rfc3986\UriQueryParams {}

        public function getQueryParams(): ?\Uri\Rfc3986\UriQueryParams {}

        public function withQueryParams(?\Uri\Rfc3986\UriQueryParams $queryParams): static {}

        ...
    }
}
</code>

<code php>
namespace Uri\WhatWg {
    final class UrlQueryParams implements \Countable
    {
        public static function parse(string $queryString): \Uri\WhatWg\UrlQueryParams {}

        public static function fromArray(array $queryParams): \Uri\WhatWg\UrlQueryParams {}
        
        public function __construct() {}

        public function append(string $name, mixed $value): static {}

        public function delete(string $name): static {}

        public function deleteValue(string $name, mixed $value): static {}

        public function has(string $name): bool {}

        public function hasValue(string $name, string $value): bool {}

        public function getFirst(string $name): ?string {}

        public function getLast(string $name): ?string {}

        public function getAll(?string $name = null): array {}
        
        public function count(): int {}

        public function set(string $name, mixed $value): static {}

        public function sort(): static {}

        public function toString(): string {}

        public function __serialize(): array {}

        public function __unserialize(array $data): void {}

        public function __debugInfo(): array {}
    }
</code>

<code php>
    final readonly class Url
    {
        ...

        public function getQueryParams(): ?\Uri\WhatWg\UrlQueryParams {}

        public function withQueryParams(?\Uri\WhatWg\UrlQueryParams $queryParams): static {}

        ...
    }
}
</code>

=== Construction ===

''UriQueryParams'' supports the following methods for instantiation:

  * **''parseRfc3986()'' method**: It parses a query string into a list of query parameters according to the RFC 3986 query syntax.
  * **''parseFormData()'' method**: It parses a query string into a list of query parameters according to the percent-encoding and decoding rules of the ''application/x-www-form-urlencoded'' media type, as defined by [[https://datatracker.ietf.org/doc/html/rfc1866#section-8.2.1RFC 1866]].
  * **''fromArray()'' method**: It takes an array of query parameters and directly composes the query parameter list object based on it.  It may be counter-intuitive, but a multi-dimension array is expected (''%%[["key1" => "value1"], ["key2" => "value2"]]%%'') instead of a single array of key-value pairs (''["key1" => "value1", "key2" => "value2"]''). This is needed to support repeated query parameter names.
  * **''%%__construct()%%''**: It accepts an empty parameter list, and results in an empty query parameter list. This method allows building query parameters by starting from scratch.

''UrlQueryParams'' supports the following methods for instantiation:

  * **''parse()'' method**: It parses a query string into a list of query parameters according to the percent-encoding and decoding rules of the ''application/x-www-form-urlencoded'' media type, as defined by the WHATWG URL specification.
  * **''fromArray()'' method**: It takes an array of query parameters and directly composes the query parameter list object based on it.  It may be counter-intuitive, but a multi-dimension array is expected (''%%[["key1" => "value1"], ["key2" => "value2"]]%%'') instead of a single array of key-value pairs (''["key1" => "value1", "key2" => "value2"]''). This is needed to support repeated query parameter names.
  * **''%%__construct()%%''**: It accepts an empty parameter list, and results in an empty query parameter list. This method allows building query parameters by starting from scratch.

<code php>
$params = Uri\Rfc3986\UriQueryParams::parse("abc=foo&abc=bar"); // Successful instantiation
$params = Uri\Rfc3986\UriQueryParams::fromArray(
    [
        ["abc" => "foo"],
        ["abc" => "bar"],
    ]
);                                                              // Successful instantiation - same result as above

$params = new Uri\Rfc3986\UriQueryParams();                     // Successful instantiation - creates an empty query parameter list

$params = Uri\WhatWg\UrlQueryParams::parse("abc=foo&abc=bar");  // Successful instantiation
$params = Uri\WhatWg\UrlQueryParams::fromArray(
    [
        ["abc" => "foo"],
        ["abc" => "bar"],
    ]
);                                                              // Successful instantiation - same result as above

$params = new Uri\WhatWg\UrlQueryParams();                      // Successful instantiation - creates an empty query parameter list
</code>

It is also possible to create a ''UriQueryParams'' or ''UrlQueryParams'' instance from an ''Uri\Rfc3986\Uri'' or an ''Uri\WhatWg\Url'' object, respectively:

<code php>
$uri = new Uri\Rfc3986\Uri("https://example.com/?foo=bar");

$params = $uri->getRawQueryParams();       // Creates a Uri\Rfc3986\UriQueryParams instance
$params = $uri->getQueryParams();          // Creates a Uri\Rfc3986\UriQueryParams instance

$url = new Uri\WhatWg\Url("https://example.com/?foo=bar");

$params = $url->getQueryParams();          // Creates a Uri\WhatWg\UrlQueryParams instance
</code>

The difference between ''Uri\Rfc3986\Uri::getRawQueryParams()'' and ''Uri\Rfc3986\Uri::getQueryParams()'' is that the former one passes the "raw" (non-normalized) query string as an input when instantiating ''Uri\Rfc3986\Uri\UriQueryParams''.

The ''Uri\Rfc3986\Uri::getRawQueryParams()'', ''Uri\Rfc3986\Uri::getQueryParams()'', ''Uri\WhatWg\Url::getQueryParams()'' methods return ''null'' if the query string is missing (e.g. https://example.com/), and an empty query parameter list is returned if the query string is empty (e.g. https://example.com/?).

<code php>
$uri = new Uri\Rfc3986\Uri("https://example.com/");
echo $uri->getRawQueryParams();            // null
echo $uri->getQueryParams();               // null

$uri = new Uri\Rfc3986\Uri("https://example.com/?");
echo $uri->getRawQueryParams();            // A new Uri\Rfc3986\Uri\UriQueryParams containing zero items
echo $uri->getQueryParams();               // A new Uri\Rfc3986\Uri\UriQueryParams containing zero items
</code>

The same example with ''Uri\WhatWg\UrlQueryParams'':

<code php>
$url = new Uri\WhatWg\Url("https://example.com/");
echo $url->getQueryParams();               // null

$url = new Uri\WhatWg\Url("https://example.com/?");
echo $url->getQueryParams();               // A new Uri\WhatWg\Url\UrlQueryParams containing zero items
</code>

It's important to note that neither ''UriQueryParams'', nor ''UrlQueryParams'' validate the query parameters appropriately during construction. This behavior is by design, because the idea of WHATWG URL's ''URLSearchParams'' class is that it's tolerant for reading, and ''UriQueryParams'' and ''UrlQueryParams'' follow the same principle. Validation happens anyway when the serialized query parameters are attempted to be written to a URI (via ''Uri\Rfc3986\Uri::withQueryParams()'' and ''Uri\WhatWg\Url::withQueryParams()''), although invalid characters are [[https://wiki.php.net/rfc/url_parsing_api#percent-encoding_decoding|automatically percent-encoded]] during recomposition - which is done under the hood when calling ''withQueryParams()'' -, before the new query is validated.

<code php>
$uri = new Uri\Rfc3986\Uri("https://example.com/");

$params = Uri\Rfc3986\UriQueryParams::parse("#foo=bar"); // Parses an invalid parameter name "#foo"

$uri = $uri->withQueryParams($params);                   // Success: the query is automatically percent-encoded to "%23foo=bar"
</code>

The same example with ''Uri\WhatWg\UrlQueryParams'':

<code php>
$url = new Uri\WhatWg\Url("https://example.com/");

$params = Uri\WhatWg\UrlQueryParams::parse("#foo=bar");  // Parses an invalid parameter name "#baz"

$url = $url->withQueryParams($params);                   // Success: the query is automatically percent-encoded to "%23foo=bar"
</code>

Neither the ''parse()'', nor the ''fromArray()'' factory methods can fail in practice: they only have memory-related failure cases which are handled by the PHP engine as a fatal error.

According to the WHATWG URL algorithm, the leading "?" character is removed during parsing. As opposed to this behavior, the leading "?" becomes part of the first query parameter name for RFC 3986 query params.

<code php>
$params = Uri\Rfc3986\UriQueryParams::parse("?abc=foo");

// $params internally contains the ["?abc" => "foo"] key-value pair

$params = Uri\WhatWg\UrlQueryParams::parse("?abc=foo");

// $params internally contains the ["abc" => "foo"] key-value pair
</code>

Another difference between the two classes is how they parse percent-encoded characters. While ''UriQueryParams'' doesn't transform any of the input, ''UrlQueryParams'' percent-decodes it automatically as per the WHATWG URL specification:

<code php>
$params = Uri\Rfc3986\UriQueryParams::parse("foo%5B%5D=b%61r"); // Percent-encoded form of "foo[]=bar"

// $params internally contains the ["foo%5B%5D" => "b%61r"] key-value pair

$params = Uri\WhatWg\UrlQueryParams::parse("foo%5B%5D=b%61r");  // Percent-encoded form of "foo[]=bar"

// $params internally contains the ["foo[]" => "bar"] key-value pair
</code>


=== Parameter Retrieval ===

The ''has()'' and ''hasValue()'' methods can be used to find out if a parameter exists:

<code php>
$params = Uri\Rfc3986\UriQueryParams::parse("foo=bar&baz=qux&baz=baz");

echo $params->has("baz");                 // true
echo $params->has("non-existent");        // false

echo $params->hasValue("foo", "bar");     // true 
echo $params->hasValue("foo", "baz");     // false
</code>

The ''has()'' method returns ''true'' if there is at least one parameter in the parameter list with the given name, ''false'' otherwise. On the other hand, ''hasValue()'' returns ''true'' if the given name and value both matches at least one parameter, otherwise it returns ''false''.

The number of query parameters can be retrieved by calling the ''count()'' method:

<code php>
$params = Uri\Rfc3986\UriQueryParams::parse("foo=bar&baz=qux&baz=baz");

echo $params->count();                 // 3
</code>

There are also a number of methods that can return a query parameter or an array of query parameters:

  * ''getFirst()'': Retrieves the first parameter with the given name. This actually implements the [[https://url.spec.whatwg.org/#dom-urlsearchparams-get|get() method]] in the WHATWG URL specification.
  * ''getLast()'': Retrieves the last parameter with the given name. It's a custom addition to the WHATWG URL specification.
  * ''getAll()'': Retrieves either all parameters if the ''$name'' parameter is ''null'', or all parameters with the given name if the ''$name'' parameter is a ''string''.

<code php>
$params = Uri\Rfc3986\UriQueryParams::parse("foo=bar&foo=baz&qux=quux");

echo $params->getFirst("foo");            // bar
echo $params->getFirst("non-existent");   // null

echo $params->getLast("foo");             // baz
echo $params->getLast("non-existent");    // null

echo $params->getAll("foo");              // [["foo", "bar"], ["foo", "baz"]]
echo $params->getAll("non-existent");     // []

echo $params->getAll(null);               // [["foo", "bar"], ["foo", "baz"], ["qux", "quux"]]
echo $params->getAll();                   // [["foo", "bar"], ["foo", "baz"], ["qux", "quux"]]
</code>

All these methods return the natively stored values without applying any transformations. That is, percent-encoding or decoding neither happens in the input, nor in the output.

<code php>
$params = Uri\Rfc3986\UriQueryParams::parse("foo%5B%5D=b%61r");  // Percent-encoded form of "foo[]=bar"

echo $params->getFirst("foo%5B%5D");     // null
echo $params->getFirst("foo[]");         // bar

echo $params->getLast("foo%5B%5D");      // null
echo $params->getLast("foo[]");          // bar

echo $params->getAll("foo%5B%5D");       // []
echo $params->getAll("foo[]");           // [["foo[]" => "bar"]]
</code>

As mentioned in the previous section, ''UrlQueryParams'' automatically performs percent-decoding during the ''parse()'' method call, so it's only possible to retrieve parameters containing percent-encoded code points if the class is instantiated via the ''fromArray()'' method, or if new items are added to the query parameter list after construction.

<code php>
$params = Uri\WhatWg\UrlQueryParams::fromArray(
    [
        ["foo%5B%5D" => "b%61r"].        // Percent-encoded form of "foo[]=bar"
    ],
);

echo $params->getFirst("foo%5B%5D");     // b%61r
echo $params->getFirst("foo[]");         // null

echo $params->getLast("foo%5B%5D");      // b%61r
echo $params->getLast("foo[]");          // null

echo $params->getAll("foo%5B%5D");       // [["foo%5B%5D" => "b%61r"]]
echo $params->getAll("foo[]");           // []
</code>

=== Percent-Encoding and Decoding ===

''UriQueryParams'' and ''UrlQueryParams'' have their distinct way of percent-encoding and decoding which is mostly similar to the behavior of RFC 3986 URIs and WHATWG URLs, but it doesn't quite work the same way. This section will discuss the specific details.

''UriQueryParams'' builds upon the [[https://wiki.php.net/rfc/url_parsing_api#parser_library_choice|uriparser library]] just like RFC 3986 URIs do. Uriparser has its custom query parameter list implementation that follows [[https://datatracker.ietf.org/doc/html/rfc1866#section-8.2.1|RFC 1866]] in the absence of any clarification in RFC 3986 about how this component should be processed apart from a description of the basic syntax. According to RFC 1866, space characters are replaced by the plus character (''+'') during percent-encoding, and any characters that fall outside of the unreserved character set are percent-encoded just like how RFC 3986 does so. Percent-decoding inverts these operations.

This behavior clearly deviates from the percent-encoding rules of the query component of RFC 3986 which allows quite a few reserved characters to be present without percent-encoding (a few examples: ":", "@", "?", "/"), not to mention the difference in how the space character is handled.

On the other hand, ''UrlQueryParams'' relies on the ''URLSearchParams'' class specified by WHATG URL, that yet again builds upon the ''application/x-www-form-urlencoded'' media type for historic reasons, albeit slightly differently than how RFC 1866 specifies it. As usually, WHATWG URL defines a [[https://url.spec.whatwg.org/#application-x-www-form-urlencoded-percent-encode-set|dedicated percent-encoding set]]:

<blockquote>The application/x-www-form-urlencoded percent-encode set contains all code points, except the ASCII alphanumeric, U+002A (*), U+002D (-), U+002E (.), and U+005F (_).</blockquote>

Also, a [[https://url.spec.whatwg.org/#urlencoded-serializing|dedicated algorithm]] for "serialization" is defined (in this context, serialization means recomposition - converting the list to a string): the space code point is percent-encoded as the plus code point (''+''), and the rest of the code points in the percent-encoding set are encoded how WHATWG URL normally does so.

This behavior deviates from the percent-encoding rules of the query component of WHATWG URL, as the [[https://url.spec.whatwg.org/#query-percent-encode-set|query percent-encode set]] contains much less characters, and the space code point is handled differently again.

It's also important to compare how the percent encoding rules of ''UriQueryParams'' and ''UrlQueryParams'' differ: they handle the asterisk (''*'') and the tilde (''~'') symbols differently: ''UriQueryParams'' percent-encodes the first one, but ''UrlQueryParams'' doesn't, however ''UriQueryParams'' doesn't percent-encode the latter one, but ''UrlQueryParams'' does so.

Even though it comes from the percent-encoding definition directly, it may still be difficult to realize that the ''application/x-www-form-urlencoded'' media type even also percent-encodes "%" itself, no matter that it's part of an existing percent-encoded octet. It's counterintuitive (normally, RFC 3986 and WHATWG URL does not percent-encode "%" twice) and quite unsafe behavior due to [[https://en.wikipedia.org/wiki/Double_encoding|double encoding]].

<code php>
$params = Uri\Rfc3986\UriQueryParams::parse("foo=b%61r");
echo $params->toString();                                 // foo=b%2561r

$params = Uri\WhatWg\UrlQueryParams::fromArray(
    [
        ["foo" => "b%61r"],
    ]
);

echo $params->toString();                                 // foo=b%2561r
</code>

As surprising as is, the ''toString()'' method percent-encodes **"%" itself** (thus "%" becomes "%25" first, and then "61r" is appended), rather than leaving the already percent-encoded octet alone.

=== Recomposition ===

In order to be consistent with the design of ''Uri\Rfc3986\Uri'' and the ''Uri\WhatWg\Url'' classes, neither ''UriQueryParams'', nor ''UrlQueryParams'' have a ''%%__toString()%%'' magic method. Instead, they contain a custom ''toString()'' method that recomposes the query string from the parameters.

<code php>
$params = Uri\Rfc3986\UriQueryParams::parse("foo=bar&foo=baz");
echo $params->toString();                // foo=bar&foo=baz

$params = Uri\WhatWg\UrlQueryParams::parse("foo=bar&foo=baz");
echo $params->toString();                // foo=bar&foo=baz
</code>

Both ''Uri\Rfc3986\UriQueryParams::toString()'' and ''Uri\WhatWg\UrlQueryParams::toString()'' automatically percent-encodes the output according to the rules outlined in the [[https://wiki.php.net/rfc/uri_followup#percent-encoding_and_decoding|previous section]].

<code php>
$params = Uri\Rfc3986\UriQueryParams::fromArray([["foo[]" => "bar baz"]]);
echo $params->toString();                // foo%5B%5D=bar+baz

$params = Uri\WhatWg\UrlQueryParams::fromArray([["foo[]" => "bar baz"]]);
echo $params->toString();                // foo%5B%5D=bar+baz
</code>

Unlike ''Uri\Rfc3986\Uri'', the ''Uri\Rfc3986\UriQueryParams'' class doesn't have a ''toRawString()'' method because it could be misleading what it exactly does: ''toRawString()'' cannot really provide a "raw" representation of the query string, since automatic percent-encoding must happen any way to make the produced query string valid.

=== Relation to the query component ===

After learning about the details of the percent-encoding and decoding behavior of ''UriQueryParams'' and ''UrlQueryParams'', it should be clarified how the new classes can interoperate with the existing ''Uri\Rfc3986\Uri'' and ''Uri\WhatWg\Url''?

The short answer is they won't have 100% compatibility. But let's see an example where things can go wrong:

<code php>
$uri = new Uri\Rfc3986\Uri("https://example.com?foo=a b");
$params = $uri->getQueryParams();
$uri = $uri->withQueryParams($params);

echo $uri->getQuery();                     // foo=a+b
</code>

The above example illustrates how the differing percent-encoding mechanisms of ''Uri\Rfc3986\Uri'' and ''Uri\Rfc3986\UriQueryParams'' affect the results: the original "foo=a b" query component is percent-encoded to "foo=a+b" during the ''$uri->withQueryParams($params)'' call. That's why the workflow is not roundtripable. ''Uri\WhatWg\UrlQueryParams'' and ''Uri\WhatWg\Url'' have the very same problem, and it's even encoded in the WHATWG URL specification itself.

=== Modification ===

The ''append()'' method can be used to append a parameter to the end of the list. As normally, the same query parameter can be added multiple times:

<code php>
$params = Uri\Rfc3986\UriQueryParams::parse("foo=bar");
$params->append("baz", "qux");
$params->append("baz", "qaz");             // Appends "baz" twice

echo $params->toString();                  // foo=bar&baz=qux&baz=qaz
</code>

Updating a parameter is possible via the ''set()'' method:

<code php>
$params = Uri\Rfc3986\UriQueryParams::parse("foo=bar&foo=baz");
$params->set("foo", "baz");                // Overwrites the first item "foo", and removes the second one
$params->set("qux", "qaz");                // Appends a new item "qux"

echo $params->toString();                  // foo=bar&baz=qux&baz=qaz
</code>

Actually, the ''set()'' method has a hybrid behavior: if a parameter is not present in the list, then it adds it just like ''append()'' does. Otherwise, it overwrites the first item, and removes the rest of the occurrences.

Neither ''append()'', nor ''set()'' do any percent-encoding or decoding of their arguments. This wasn't a question for RFC 3986 though (because it never does so), but WHATWG URL usually post-processes its input automatically.

<code php>
$params = Uri\WhatWg\UrlQueryParams::parse("");
$params->append("foo%5B%5D", "ab%63");     // Percent-encoded form of "foo[]=abc"
$params->set("bar%5B%5D", "de%66");        // Percent-encoded form of "bar[]=def"

echo $params->toString();                  // foo%255B%255D=ab%2563&bar%255B%255D=de%2566
</code>

As it can be seen, percent-encoded octets received during the ''append()'' and ''set()'' method calls were double-encoded in the final output, as warned by the [[https://wiki.php.net/rfc/uri_followup#percent-encoding_and_decoding|Percent-Encoding and Decoding]] section. This means, ''foo%5B%5D'' and the rest of the input was accepted as-is, and then they got percent-encoded again during the ''toString()'' call.

Removing parameters is possible via either the ''delete()'' or the ''deleteValue()'' method: the former one removes all occurrences of the given parameter name, while the latter one removes all occurrences of a parameter if the given name and value both matches it, as demonstrated below:

<code php>
$params = Uri\Rfc3986\UriQueryParams::parse("foo=bar&foo=baz&foo=qux");
$params->deleteValue("foo", "baz");    // Deletes the "foo=baz" parameter
$params->delete("foo");                    // Deletes the rest of the occurrences: "foo=bar" and "foo=qux"
$params->delete("non-existent");           // The parameter is not present: nothing happens
</code>

The last method that can modify the list is ''sort()'', which sorts the parameters alphabetically:

<code php>
$params = Uri\Rfc3986\UriQueryParams::parse("foo=bar&baz=qux&baz=baz");
$params->sort();

echo $params->toString();                  // baz=baz&baz=qux&foo=bar
</code>

=== Type support ===

What's also important to clarify is how non-string values are mapped? PHP's [[http_build_query()|https://www.php.net/manual/en/function.http-build-query.php]] and functions can map basically any type to query params, however, the exact behavior is not specified by either RFC 3986 or WHATWG URL: RFC 3986 completely omits any information how query parameters should be build, while WHATWG URL's ''URLSearchParams'' only accepts and returns string data.

The position of this RFC is that it's important to follow the road that ''http_build_query()'' has already paved because of better developer experience and better interoperability with the existing ecosystem. That's why the following type mapping behavior is proposed **when a query parameter is added/updated**:

  * **bool:** becomes string "0" (in case of ''false'') or string "1" (in case of ''true'')
  * **int:** becomes a numeric string (123 -> "123")
  * **float:** becomes a decimal string (3.14 -> "3.14")
  * **resource:** invalid mapping, throws a ''TypeError''
  * **array:** TBD
  * **object:** TBD

The above conversion rules work for both ''UriQueryParams'' and ''UrlQueryParams''. However, ''Uri\Rfc3986\UriQueryParams'' can additionally properly handle ''null'' values: a ''null'' input is mapped to a query component so that only the parameter name is present - the "=" and the parameter value is omitted. On the other hand, ''Uri\WhatWg\UrlQueryParams'' converts ''null'' values to an empty string. Alternatively, it could omit parameters with ''null'' values completely, the same way as ''http_build_query()'' does.

<code php>
$params = Uri\Rfc3986\UriQueryParams::parse("");

$params->append("param_null", null);
$params->append("param_bool", true);
$params->append("param_int", 123);
$params->append("param_float", 3.14);

var_dump($params->getFirst("param_null"));  // NULL
var_dump($params->getFirst("param_bool"));  // string(1) "1"
var_dump($params->getFirst("param_int"));   // string(3) "123"
var_dump($params->getFirst("param_float")); // string(4) "3.14"

echo $params->toString();                   // param_null&param_bool=1&param_int=123&param_float=3.14
</code>

Note how ''UrlQueryParams'' works differently with regards to ''null'' values:

<code php>
$params = Uri\WhatWg\UrlQueryParams::parse("");

$params->append("param_null", null);
$params->append("param_bool", true);
$params->append("param_int", 123);
$params->append("param_float", 3.14);

var_dump($params->getFirst("param_null"));  // string(0) ""
var_dump($params->getFirst("param_bool"));  // string(1) "1"
var_dump($params->getFirst("param_int"));   // string(3) "123"
var_dump($params->getFirst("param_float")); // string(4) "3.14"

echo $params->toString();                   // param_null=&param_bool=1&param_int=123&param_float=3.14
</code>

Exact array and object casting rules are still to be decided.

=== Implemented Interfaces ===

The ''UriQueryParams'' and ''UrlQueryParams'' classes could implement the ''IteratorAggregate'' interface in theory. However, it's not possible to do so due to query components that share the same name, e.g.: ''param=foo&param=bar&param=baz''. In this case, the same key (''param'') would be repeated 3 times - and it's actually not possible to support with iterators.

=== Cloning ===

Cloning of ''UriQueryParams'' and ''UrlQueryParams'' is supported.

<code php>
$params1 = Uri\Rfc3986\UriQueryParams::parse("foo=bar&foo=baz");
$params2 = clone $params1;

echo $params1->toString();               // foo=bar&foo=baz
echo $params2->toString();               // foo=bar&foo=baz
</code>

''UrlQueryParams'' works the same way:

<code php>
$params1 = Uri\WhatWg\UrlQueryParams::parse("foo=bar&foo=baz");
$params2 = clone $params1;

echo $params1->toString();                // foo=bar&foo=baz
echo $params2->toString();                // foo=bar&foo=baz
</code>

=== Serialization ===

Both classes are serializable and deserializable. The only implementation gotcha is that the serialized format is slightly unexpected: instead of recomposing the query params into a query string, the individual key-value pairs are serialized as an array. This is necessary because both ''toString'' implementations automatically percent-encode the input, so using these algorithms would skew the original data, not to mention the fact that ''Uri\WhatWg\UrlQueryParams::parse()'' performs automatic percent-decoding too.

=== Debugging ===

Both classes contain a ''%%__debugInfo()%%'' method that returns all items in the query parameter list in order to make debugging easier.

<code php>
$params = Uri\Rfc3986\UriQueryParams::parse("foo=bar&foo=baz&foo=qux");
var_dump($params);

/*
object(Uri\Rfc3986\UriQueryParams)#1 (1) {
  ["params"]=> array(3) {
    [0]=>
    array(1) {
      ["foo"]=>
      string(3) "bar"
    }
    [1]=>
    array(1) {
      ["foo"]=>
      string(3) "baz"
    }
    [2]=>
    array(1) {
      ["foo"]=>
      string(3) "qux"
    }
  }
}
*/

$params = Uri\WhatWg\UrlQueryParams::parse("foo=bar&foo=baz&foo=qux");
var_dump($params);

/*
object(Uri\WhatWg\UrlQueryParams)#1 (1) {
  ["params"]=> array(3) {
    [0]=>
    array(1) {
      ["foo"]=>
      string(3) "bar"
    }
    [1]=>
    array(1) {
      ["foo"]=>
      string(3) "baz"
    }
    [2]=>
    array(1) {
      ["foo"]=>
      string(3) "qux"
    }
  }
}
*/
</code>

=== Vote ===

<doodle title="Add support for query parameter manipulation as outlined in the RFC?" voteType="single" closed="true" closeon="2025-01-01T15:30:00Z">
   * Yes
   * No
   * Abstain
</doodle>

==== Accessing Path Segments as an Array ====

Sometimes, accessing path segments rather than the whole path as string is needed. When this is the case, splitting the path to segments manually after retrieval is both inconvenient and disadvantageous performance-wise, especially considering the fact that ''Uri\Rfc3986\Uri'' internally stores the path as a list of segments.

That's why the following methods are proposed to be added:

<code php>
namespace Uri\Rfc3986 {
    final readonly class Uri
    {
        ...

        public function getRawPathSegments(): array {}

        public function getPathSegments(): array {}

        public function withPathSegments(array $segments, bool $addLeadingSlashForNonEmptyRelativeUri = true): static {}

        ...
    }
}
</code>

<code php>
namespace Uri\WhatWg {
    final readonly class Url
    {
        ...

        public function getPathSegments(): array {}

        public function withPathSegments(array $segments): static {}

        ...
    }
}
</code>

This way, it is possible to write the following code:

<code php>
$uri = new Uri\Rfc3986\Uri("https://example.com/foo/bar/baz");
$segments = $uri->getPathSegments();        // ["foo", "bar", "baz"]

$uri = $uri->withPathSegments(["a", "b"]);
echo $uri->getPath();                       // /a/b
</code>

The same also works for WHATWG URL:

<code php>
$url = new Uri\WhatWg\Url("https://example.com/foo/bar/baz");
$segments = $url->getPathSegments();        // ["foo", "bar", "baz"]

$url = $url->withPathSegments(["a", "b"]);
echo $url->getPath();                       // /a/b
</code>

In order to understand better why and exactly how this functionality works, we should more carefully understand how RFC 3986 defines the path and path segments: according to the specification, path segments start after the leading "/" in the path due to the following ABNF rule:

<code>
path-abempty  = *( "/" segment )
</code>

That is, the ''path-abempty'' syntax only applies in case of URIs containing an [[https://datatracker.ietf.org/doc/html/rfc3986#section-3.2|authority]] component, and it declares that the path is either empty, or contains a "/" followed by a segment one or multiple times. Then segments have the following syntax:

<code>
segment       = *pchar
pchar         = unreserved / pct-encoded / sub-delims / ":" / "@"
</code>

That is, segments are composed of zero or multiple characters in the "pchar" charset (the exact values don't matter in this case). It should be mentioned that there are some additional special-case segment syntaxes (they are marked with ''segment-nz'' and ''segment-nz-nc'' in the ABNF syntax), but let's disregard them now for ease of understanding.

The above definitions imply that an empty path has zero segments:

<code php>
$uri = new Uri\Rfc3986\Uri("https://example.com");
$segments = $uri->getPathSegments();        // []
</code>

When the path consists of a leading "/" and a string matching the ''segment'' syntax (e.g. ''/foo''), the path has one segment:

<code php>
$uri = new Uri\Rfc3986\Uri("https://example.com/foo");
$segments = $uri->getPathSegments();        // ["foo"]
</code>

We can easily see based on the above example that the URI ''https://example.com/'' also has a single segment - but it's empty: 

<code php>
$uri = new Uri\Rfc3986\Uri("https://example.com/");
$segments = $uri->getPathSegments();        // [""]
</code>

This is perfectly valid, because segments can be empty (at least in the above case when the URI has an authority). Another interesting question is how segments are represented when the path has a trailing slash (e.g. ''/foo/'')? Consistent to the above rules, it's the following:

<code php>
$uri = new Uri\Rfc3986\Uri("https://example.com/foo/");
$segments = $uri->getPathSegments();        // ["foo", ""]
</code>

A few other special cases are also collected below:

  * "%%https://%%": It means that the URI has an empty authority starting after the "%%//%%" characters, therefore the path is also empty, and therefore this URI has zero path segments
  * "https:/": It means that the UR has no authority and the path starts after the ":" character (it is "/"), therefore this URI has one empty path segment
  * "https:": It means that the URI has no authority, and the path starts after the ":" character (it is ""), therefore this URI has zero path segments
  * "" (empty string): It means that the relative reference consists of a single path component which is empty, and therefore this relative reference has zero path segments
  * "/foo": It means that the relative reference consists of a single path component which is "/foo", and therefore this relative reference has one path segment "foo"
  * "foo": It means that the relative reference consists of a single path component which is "foo", and therefore this relative reference has one path segment "foo"
  * "foo/": It means that the relative reference consists of a single path component which is "foo/", and therefore this relative reference has two path segments "foo" and ""
  * "/": It means that the relative reference consists of a single path component which is "/", and therefore this relative reference has one empty path segment

The above described behavior satisfies the definitions of RFC 3986. However, one case needs disambiguation in relation to the ''withPathSegments()'' method: "/foo" vs "foo".

That's why ''Uri\Rfc3986\Uri::withPathSegments()'' has a second parameter ''$addLeadingSlashForNonEmptyRelativeUri'', which can be used to decide if a relative reference should became an absolute- or a relative-path reference:

<code php>
$uri = new Uri\Rfc3986\Uri("/foo");            // absolute-path reference

$uri = $uri->withPathSegments(["bar"], false); // The leading slash is not prepended

echo $uri->getPath();                          // bar

$uri = new Uri\Rfc3986\Uri("foo");             // relative-path reference

$uri = $uri->withPathSegments(["bar"], true);  // The leading slash is prepended

echo $uri->getPath();                          // /bar
</code>

The ''$addLeadingSlashForNonEmptyRelativeUri'' parameter only has effect when the URI is a relative reference, and the first path segment is not empty, any other cases are unambiguous.

''Uri\Rfc3986\Uri::withPathSegments()'' and ''Uri\WhatWg\Url::withPathSegments()'' internally concatenate the input segments separated by a ''/'' character, and then trigger ''Uri\Rfc3986\Uri::withPath()'' and  ''Uri\WhatWg\Url::withPath()'', respectively.

<doodle title="Add support for accessing path segments as an array as outlined in the RFC?" voteType="single" closed="true" closeon="2025-01-01T15:30:00Z">
   * Yes
   * No
   * Abstain
</doodle>

==== Host Type Detection ====

Both the RFC 3986 and WHATWG URL specifications distinguish different types of the host component because each of them have different parsing and formatting rules. Probably the most notable example is the IPv6 host type that requires the IPv6 address to be written between a ''['' and '']'' pair.

In order to support returning information about the host type, the following enums and methods are proposed to be added:

<code php>
namespace Uri\Rfc3986 {
    enum UriHostType
    {
        case IPv4;
        case IPv6;
        case IPvFuture;
        case RegisteredName;
    }

    final readonly class Uri
    {
        ...

        public function getHostType(): ?\Uri\Rfc3986\UriHostType {}

        ...
    }
}
</code>

<code php>
namespace Uri\WhatWg {
    enum UrlHostType
    {
        case IPv4;
        case IPv6;
        case Domain;
        case Opaque;
        case Empty;
    }

    final readonly class Url
    {
        ...

        public function getHostType(): ?\Uri\WhatWg\UrlHostType {}

        ...
    }
}
</code>

The new ''getHostType()'' methods return the type of the host component for both specifications:

<code php>
$uri = new Uri("https://192.168.0.1/");
echo $uri->getHostType();                  // UriHostType::IPv4

$uri = new Uri("https://[2001:db8::1]/");
echo $uri->getHostType();                  // UriHostType::IPv6

$uri = new Uri("https://[v1.1.2.3]/");
echo $uri->getHostType();                  // UriHostType::IPvFuture

$uri = new Uri("https://example.com/");
echo $uri->getHostType();                  // UriHostType::RegisteredName

$uri = new Uri("/foo/bar");
echo $uri->getHostType();                  // null
</code>

The same for WHATWG URL:

<code php>
$url = new Uri\WhatWg\Url("https://192.168.0.1/");
echo $url->getHostType();                  // UrlHostType::IPv4

$url = new Uri\WhatWg\Url("https://[2001:db8::1]/");
echo $uri->getHostType();                  // UrlHostType::IPv6

$url = new Uri\WhatWg\Url("https://example.com/");
echo $url->getHostType();                  // UrlHostType::Domain

$url = new Uri\WhatWg\Url("scheme://example.com/");
echo $url->getHostType();                  // UrlHostType::Opaque

$url = new Uri\WhatWg\Url("mailto://john.doe@example.com");
echo $url->getHostType();                  // UrlHostType::Empty

$url = new Uri\WhatWg\Url("scheme://john.doe@example.com");
echo $url->getHostType();                  // null
</code>

<doodle title="Add support for host type detection as outlined in the RFC?" voteType="single" closed="true" closeon="2025-01-01T15:30:00Z">
   * Yes
   * No
   * Abstain
</doodle>

==== URI Type Detection ====

RFC 3986 distinguishes different URI "types" based on what they begin with. Actually, the RFC 3986 specification collectively  refers to these as URI-references.

  * **Relative-reference:** Starts with a path, and the scheme is therefore omitted. Relative-references can be further grouped into the following types:
    * **Absolute-path reference:** Starts with a single slash ("**/**"), e.g.: "/foo"
    * **Relative-path reference:** Starts without a slash ("**/**"), e.g.: "foo"
    * **Network-path reference:** Starts with a double slash ("**%%//%%**") followed by an authority, e.g.: ''%%//host/foo%%''
  * **URI:** Starts with the scheme component, and then continues with either the authority, or the path
    * **Absolute URI:** A subtype of URIs are absolute URIs which don't include the fragment component.

In order to better support granular RFC 3986 URI type detection, the following enums and methods are proposed to be added:

<code php>
namespace Uri\Rfc3986 {
    enum UriType
    {
        case AbsolutePathReference;
        case RelativePathReference;
        case NetworkPathReference;
        case Uri;
    }

    final readonly class Uri
    {
        ...

        public function getUriType(): Uri\Rfc3986\UriType {}

        ...
    }
}
</code>

This way, it becomes easier to detect URI types:

<code php>
$uri = new Uri\Rfc3986\Uri("https://example.com");
var_dump($uri->getUriType());                     // Uri\Rfc3986\UriType::Uri

$uri = new Uri\Rfc3986\Uri("https:");
var_dump($uri->getUriType());                     // Uri\Rfc3986\UriType::Uri

$uri = new Uri\Rfc3986\Uri("/foo");
var_dump($uri->getUriType());                     // Uri\Rfc3986\UriType::AbsolutePathReference

$uri = new Uri\Rfc3986\Uri("foo");
var_dump($uri->getUriType());                     // Uri\Rfc3986\UriType::RelativePathReference

$uri = new Uri\Rfc3986\Uri("//host.com/foo");
var_dump($uri->getUriType());                     // Uri\Rfc3986\UriType::NetworkPathReference
</code>

The position of this RFC is that identifying the distinction between URIs and absolute URIs doesn't need special support, therefore a dedicated ''Uri\Rfc3986\UriType'' enum case is omitted.

The WHATWG URL specification defines some [[https://url.spec.whatwg.org/#is-special|special schemes]] (''http'', ''https'', ''ftp'', ''file'', ''ws'', ''wss''), which have distinct parsing and serialization rules. In order to make checks for special URLs easier to perform, a new ''Uri\WhatWg\Url::isSpecialScheme()'' method is added:

<code php>
namespace Uri\WhatWg {
    final readonly class Url
    {
        ...

        public function isSpecialScheme(): bool {}

        ...
    }
}
</code>

This enables low-level control for applications that need to mirror WHATWG behaviors in parsing or normalization.

<code php>
$url = new Uri\WhatWg\Url("https://example.com");
var_dump($url->isSpecialScheme());                // true

$url = new Uri\WhatWg\Url("custom:example");
var_dump($url->isSpecialScheme());                // false
</code>

<doodle title="Add support for detecting URI type as outlined in the RFC?" voteType="single" closed="true" closeon="2025-01-01T15:30:00Z">
   * Yes
   * No
   * Abstain
</doodle>

==== Percent-Encoding and Decoding Support ====

Contrarily to the common belief that's probably further affirmed by the ''urlencode()'' and ''urldecode()'' functions, percent-encoding and decoding are [[https://wiki.php.net/rfc/url_parsing_api#percent-encoding_decoding|both a context-sensitive process]]. Context-sensitivity means that different characters need to be percent-encoded/percent-encoded depending on which URI component is being processed.

<blockquote>It should also be mentioned that in fact, ''urlencode()'' and ''urldecode()'' should rather be used for the ''application/x-www-form-urlencoded'' media type, and ''rawurlencode()'' and ''rawurldecode()'' more closely implements RFC 3986.
</blockquote>

For example, the path component dedicates special meaning for the ''/'' character. Therefore, this character doesn't necessarily have to be percent-encoded in the path component. There are some cases though when it makes sense to percent-encode them, as highlighted by the [[https://wiki.php.net/rfc/url_parsing_api#advanced_examples|first example]] within the "Advanced examples" section of the original URI RFC. Unfortunately, ''rawurlencode()'' doesn't take the component into account, and replaces the "/" with "%2F" unconditionally.

<code php>
echo rawurlencode("/foo/bar/baz");                // %2Ffoo%2Fbar%2Fbaz
</code>

In order to correctly handle percent-encoding and decoding based on the rules of RFC 3986 and WHATWG URL, the following methods and enums are proposed to be added:

<code php>
namespace Uri\Rfc3986 {
    enum UriPercentEncodingMode
    {
        case UserInfo;
        case Host;
        case RelativeReferencePath;
        case RelativeReferenceFirstPathSegment;
        case Path;
        case PathSegment;
        case Query;
        case FormQuery;
        case Fragment;
        case AllReservedCharacters;
        case All;
    }

    final readonly class Uri
    {
        ...

        public static function percentEncode(string $input, \Uri\Rfc3986\UriPercentEncodingMode $mode): string {}

        public static function percentDecode(string $input, \Uri\Rfc3986\UriPercentEncodingMode $mode): string {}

        ...
    }
}
</code>

<code php>
namespace Uri\WhatWg {
    enum UrlPercentEncodingMode
    {
        case UserInfo;
        case Host;
        case OpaqueHost;
        case Path;
        case PathSegment;
        case OpaquePath;
        case OpaquePathSegment;
        case Query;
        case SpecialQuery;
        case FormQuery;
        case Fragment;
    }

    final readonly class Url
    {
        ...

        public static function percentEncode(string $input, \Uri\WhatWg\UrlPercentEncodingMode $mode): string {}

        public static function percentDecode(string $input, \Uri\WhatWg\UrlPercentEncodingMode $mode): string {}

        ...
    }
}
</code>

The ''percentEncode()'' and ''percentDecode()'' methods both require an input string and a ''PercentEncodingMode'' enum to be passed. The enums make the context of the encoding/decoding processes fully explicit and clear. The following modes are supported:

  * **Uri\Rfc3986\UriPercentEncodingMode**
    * **UserInfo:** Besides [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.3|unreserved characters]], [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.1|percent-encoded octets]], as well as [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.2|sub-delimiters]], it also allows the following characters to be present: "**:**". Any other characters are percent-encoded.
    * **Host:** If the input string is a valid IPv4, an IPv6 or an IPvFuture address, no percent-encoding is performed, since these host types do not support the process. Otherwise (for registered names), [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.3|unreserved characters]], [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.1|percent-encoded octets]], as well as [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.2|sub-delimiters]] are allowed to be present. Any other characters are percent-encoded.
    * **AbsolutePathReferenceFirstSegment:** The first segment of absolute-path references cannot start with "**%%//%%**" characters (e.g. ''%%//foo%%''), otherwise the path [[https://datatracker.ietf.org/doc/html/rfc3986#section-4.2|would be confusable]] with a network-path reference. Therefore, besides [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.3|unreserved characters]], [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.1|percent-encoded octets]], as well as [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.2|sub-delimiters]], it also allows the following characters to be present: "**:**", "**@**". Any other characters are percent-encoded.
    * **RelativePathReferenceFirstSegment:** The first segment of relative-path references cannot contain a "**:**" character (e.g. ''this:that''), otherwise the path [[https://datatracker.ietf.org/doc/html/rfc3986#section-4.2|would be confusable]] with a scheme name. Therefore, besides [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.3|unreserved characters]], [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.1|percent-encoded octets]], as well as [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.2|sub-delimiters]], it also allows the following characters to be present: "**@**". Any other characters are percent-encoded.
    * **RelativeReferencePath:** 
    * **Path:** Besides [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.3|unreserved characters]], [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.1|percent-encoded octets]], as well as [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.2|sub-delimiters]], it also allows the following characters to be present: "**/**", "**:**", "**@**". Any other characters are percent-encoded.
    * **PathSegment:** Besides [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.3|unreserved characters]], [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.1|percent-encoded octets]], as well as [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.2|sub-delimiters]], it also allows the following characters to be present: "**:**", "**@**". Any other characters are percent-encoded.
    * **Query:** Besides [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.3|unreserved characters]], [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.1|percent-encoded octets]], as well as [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.2|sub-delimiters]], it also allows the following characters to be present: "**:**", "**@**", "**/**", and "**?**". Any other characters are percent-encoded.
    * FormQuery: It is mostly the same as ''Uri\Rfc3986\UriPercentEncodingMode::Query'', but it behaves according to the ''application/x-www-form-urlencode'' media type rather than RFC 3986. The only difference between the two is that " " is encoded as "**+**".
    * Fragment: Besides [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.3|unreserved characters]], [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.1|percent-encoded octets]], as well as [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.2|sub-delimiters]], it also allows the following characters to be present: "**:**", "**@**", "**/**", and "**?**". Any other characters are percent-encoded.
    * AllReservedCharacters: All [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.2|reserved characters]] are percent-encoded. The rest of the characters are left as-is.
    * AllButUnreservedCharacters: Besides [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.3|unreserved characters]] and [[https://datatracker.ietf.org/doc/html/rfc3986#section-2.1|percent-encoded octets]], all other characters are percent-encoded.

For the complete ABNF syntax of each component, consult [[https://datatracker.ietf.org/doc/html/rfc3986#appendix-A|Appendix A]] of RFC 3986.

  * **Uri\WhatWg\UrlPercentEncodingMode**
    * **UserInfo:** Besides the code points percent-encoded by ''Uri\WhatWg\UrlPercentEncodingMode::Path'', the following code points are percent-encoded: U+002F (**/**), U+003A (**:**), U+003B (**;**), U+003D (**=**), U+0040 (**@**), U+005B (**[**) to U+005D (**]**), inclusive, and U+007C (**|**).
    * **OpaqueHost:** [[https://infra.spec.whatwg.org/#c0-control|Control characters]], and all [[https://url.spec.whatwg.org/#c0-control-percent-encode-set|code points greater than ~]] are percent-encoded.
    * **Path:** Besides the code points percent-encoded by ''Uri\WhatWg\UrlPercentEncodingMode::Query'', the following code points are percent-encoded: U+003F (**?**), U+005E (**^**), U+0060 (**`**), U+007B (**{**), and U+007D (**}**).
    * **PathSegment:** Besides the code points percent-encoded by ''Uri\WhatWg\UrlPercentEncodingMode::Query'', the following code points are percent-encoded: U+003F (**?**), U+005E (**^**), U+0060 (**`**), U+007B (**{**), U+007D (**}**), and U+002F (**/**).
    * **OpaquePathSegment:**
    * **Query:** Besides [[https://infra.spec.whatwg.org/#c0-control|Control characters]], and all [[https://url.spec.whatwg.org/#c0-control-percent-encode-set|code points greater than ~]], the following code points are percent-encoded: U+0020 SPACE, U+0022 (**"**), U+0023 (**#**), U+003C (**<**), and U+003E (**>**).
    * **SpecialQuery:** Besides the code points percent-encoded by ''Uri\WhatWg\UrlPercentEncodingMode::Query'', the following code points are percent-encoded: U+0027 (**'**)
    * **FormQuery:** Besides the code points percent-encoded by ''Uri\WhatWg\UrlPercentEncodingMode::UserInfo'', the following code points are percent-encoded: U+0024 (**$**) to U+0026 (**&**), inclusive, U+002B (**+**), U+002C (**,**), U+0021 (**!**), U+0027 (**'**) to U+0029 RIGHT PARENTHESIS, inclusive, and U+007E (**~**).
    * **Fragment:** Besides [[https://infra.spec.whatwg.org/#c0-control|Control characters]], and all [[https://url.spec.whatwg.org/#c0-control-percent-encode-set|code points greater than ~]], the following code points are percent-encoded: U+0020 SPACE, U+0022 (**"**), U+003C (**<**), U+003E (**>**), and U+0060 (**`**).

Since neither RFC 3986, nor WHATWG URL support percent-encoded characters inside the scheme component, none of the enums contain a ''Scheme'' case. WHATWG URL automatically percent-decodes the host when [[https://wiki.php.net/rfc/uri_followup#determining_if_the_whatwg_url_is_special|it's special]], so ''Uri\WhatWg\UrlPercentEncodingMode'' doesn't contain a ''Host'' case.

The ''percentDecode()'' methods perform the inverted operation of ''percentEncode()'': it decodes every character that is percent-encoded, but which are otherwise allowed by the current percent-encoding mode.

<code php>
$uri = new Uri\Rfc3986\Uri("https://example.com#_%40%2F"); // The fragment is the percent-encoded form of "_@/"

echo Uri\Rfc3986\Uri::percentDecode(
    $uri->getFragment(),
    Uri\Rfc3986\UriPercentEncodingMode::Fragment
);                                                         // _%40/
</code>

The "/" character is allowed in the fragment, so it's needlessly percent-encoded in the URI - that's why it can be percent-decoded by ''percentDecode()''. On the other hand, "@" is not supported in the context of the fragment, so it's kept in the percent-encoded octet form.

RFC 3986 has a sentence that apparently contradicts with the behavior of ''Uri\Rfc3986\Uri::percentDecode()'':

> Thus, characters in the reserved set are protected from normalization and are therefore safe to be used by scheme-specific and producer-specific algorithms for delimiting data subcomponents within a URI.

According to this rule, reserved characters - even if they are allowed in the context of a component - should not be percent-decoded during normalization. Even though the ''Uri\Rfc3986\Uri'' getters respect this rule, the ''percentDecode()'' method intentionally disregards it so that it can serve in use-cases where those getters cannot. Let's see an example:

<code php>
$uri = new Uri\Rfc3986\Uri("https://example.com/?q=%3A%29"); // The query is the percent-encoded form of ":)"

echo $uri->getQuery();                            // %3A%29

echo Uri\Rfc3986\Uri::percentDecode(
    $uri->getQuery(),
    Uri\Rfc3986\UriPercentEncodingMode::Query
);                                                // :)
</code>

As it can be seen above, the ''getQuery()'' getter only normalizes the "%20" percent-encoded octet, and it leaves the two reserved characters (":" and ")") as-is, even though both ":" and ")" are allowed in the context of the query (so they shouldn't be percent-encoded at all). By using ''percentDecode()'' one can make the input consumable directly, and scheme-specific or producer-specific algorithms should continue to use the getters should they need to perform any kind of custom processing.

By using the proposed percent-encoding and decoding capabilities, many use-cases will become possible to implement in a specification-compliant way which was difficult to achieve before.

For example, path segments can be properly percent-encoded when they contain the ''/'' character:

<code php>
$uri = new Uri\Rfc3986\Uri("https://example.com");
$uri = $uri->withPathSegments(
    [
        "foo",
        Uri\Rfc3986\Uri::percentEncode("bar/baz", Uri\Rfc3986\UriPercentEncodingMode::PathSegment)
    ]
);

$uri->toRawString();                              // https://example.com/foo/bar%2Fbaz
</code>

<doodle title="Add support for percent-encoding and decoding as outlined in the RFC?" voteType="single" closed="true" closeon="2025-01-01T15:30:00Z">
   * Yes
   * No
   * Abstain
</doodle>

===== Backward Incompatible Changes =====

All the proposed changes are completely backward compatible because the affected classes are all [[https://wiki.php.net/rfc/url_parsing_api#why_should_the_uri_rfc3986_uri_and_the_uri_whatwg_url_classes_be_final|final]].

===== Proposed PHP Version(s) =====

Next minor version (PHP 8.6 most likely)

===== RFC Impact =====

==== To the Ecosystem ====

What effect will the RFC have on IDEs, Language Servers (LSPs), Static Analyzers, Auto-Formatters, Linters and commonly used userland PHP libraries?

==== To Existing Extensions ====

Existing extensions can continue to use the existing URI API without any changes. Some of the features are exposed as ''PHPAPI'' functions through public headers.

==== To SAPIs ====

None.

===== Open Issues =====

None.

===== Future Scope =====

None.

===== Patches and Tests =====

https://github.com/kocsismate/php-src/pull/9

===== Implementation =====

After the RFC is implemented, this section should contain:
  - the version(s) it was merged into
  - a link to the git commit(s)
  - a link to the PHP manual entry for the feature

===== References =====

  * [[https://wiki.php.net/rfc/url_parsing_api|Add RFC 3986 and WHATWG URL compliant API]]

===== Rejected Features =====

None.

===== Changelog =====