spqr/vendor/guzzlehttp/psr7/README.md

PSR-7 Message Implementation

This repository contains a full PSR-7 message implementation, several stream decorators, and some helpful functionality like query string parsing.

Features

This package comes with a number of stream implementations and stream decorators.

Installation

composer require guzzlehttp/psr7

Version Guidance

Version	Status	PHP Version
1.x	EOL (2024-06-30)	>=5.4,<8.2
2.x	Latest	>=7.2.5,<8.5

AppendStream

GuzzleHttp\Psr7\AppendStream

Reads from multiple streams, one after the other.

use GuzzleHttp\Psr7;

$a = Psr7\Utils::streamFor('abc, ');
$b = Psr7\Utils::streamFor('123.');
$composed = new Psr7\AppendStream([$a, $b]);

$composed->addStream(Psr7\Utils::streamFor(' Above all listen to me'));

echo $composed; // abc, 123. Above all listen to me.

BufferStream

GuzzleHttp\Psr7\BufferStream

Provides a buffer stream that can be written to fill a buffer, and read from to remove bytes from the buffer.

This stream returns a "hwm" metadata value that tells upstream consumers what the configured high water mark of the stream is, or the maximum preferred size of the buffer.

use GuzzleHttp\Psr7;

// When more than 1024 bytes are in the buffer, it will begin returning
// false to writes. This is an indication that writers should slow down.
$buffer = new Psr7\BufferStream(1024);

CachingStream

The CachingStream is used to allow seeking over previously read bytes on non-seekable streams. This can be useful when transferring a non-seekable entity body fails due to needing to rewind the stream (for example, resulting from a redirect). Data that is read from the remote stream will be buffered in a PHP temp stream so that previously read bytes are cached first in memory, then on disk.

use GuzzleHttp\Psr7;

$original = Psr7\Utils::streamFor(fopen('http://www.google.com', 'r'));
$stream = new Psr7\CachingStream($original);

$stream->read(1024);
echo $stream->tell();
// 1024

$stream->seek(0);
echo $stream->tell();
// 0

DroppingStream

GuzzleHttp\Psr7\DroppingStream

Stream decorator that begins dropping data once the size of the underlying stream becomes too full.

use GuzzleHttp\Psr7;

// Create an empty stream
$stream = Psr7\Utils::streamFor();

// Start dropping data when the stream has more than 10 bytes
$dropping = new Psr7\DroppingStream($stream, 10);

$dropping->write('01234567890123456789');
echo $stream; // 0123456789

FnStream

GuzzleHttp\Psr7\FnStream

Compose stream implementations based on a hash of functions.

Allows for easy testing and extension of a provided stream without needing to create a concrete class for a simple extension point.

use GuzzleHttp\Psr7;

$stream = Psr7\Utils::streamFor('hi');
$fnStream = Psr7\FnStream::decorate($stream, [
    'rewind' => function () use ($stream) {
        echo 'About to rewind - ';
        $stream->rewind();
        echo 'rewound!';
    }
]);

$fnStream->rewind();
// Outputs: About to rewind - rewound!

InflateStream

GuzzleHttp\Psr7\InflateStream

Uses PHP's zlib.inflate filter to inflate zlib (HTTP deflate, RFC1950) or gzipped (RFC1952) content.

This stream decorator converts the provided stream to a PHP stream resource, then appends the zlib.inflate filter. The stream is then converted back to a Guzzle stream resource to be used as a Guzzle stream.

LazyOpenStream

GuzzleHttp\Psr7\LazyOpenStream

Lazily reads or writes to a file that is opened only after an IO operation take place on the stream.

use GuzzleHttp\Psr7;

$stream = new Psr7\LazyOpenStream('/path/to/file', 'r');
// The file has not yet been opened...

echo $stream->read(10);
// The file is opened and read from only when needed.

LimitStream

GuzzleHttp\Psr7\LimitStream

LimitStream can be used to read a subset or slice of an existing stream object. This can be useful for breaking a large file into smaller pieces to be sent in chunks (e.g. Amazon S3's multipart upload API).

use GuzzleHttp\Psr7;

$original = Psr7\Utils::streamFor(fopen('/tmp/test.txt', 'r+'));
echo $original->getSize();
// >>> 1048576

// Limit the size of the body to 1024 bytes and start reading from byte 2048
$stream = new Psr7\LimitStream($original, 1024, 2048);
echo $stream->getSize();
// >>> 1024
echo $stream->tell();
// >>> 0

MultipartStream

GuzzleHttp\Psr7\MultipartStream

Stream that when read returns bytes for a streaming multipart or multipart/form-data stream.

NoSeekStream

GuzzleHttp\Psr7\NoSeekStream

NoSeekStream wraps a stream and does not allow seeking.

use GuzzleHttp\Psr7;

$original = Psr7\Utils::streamFor('foo');
$noSeek = new Psr7\NoSeekStream($original);

echo $noSeek->read(3);
// foo
var_export($noSeek->isSeekable());
// false
$noSeek->seek(0);
var_export($noSeek->read(3));
// NULL

PumpStream

GuzzleHttp\Psr7\PumpStream

Provides a read only stream that pumps data from a PHP callable.

When invoking the provided callable, the PumpStream will pass the amount of data requested to read to the callable. The callable can choose to ignore this value and return fewer or more bytes than requested. Any extra data returned by the provided callable is buffered internally until drained using the read() function of the PumpStream. The provided callable MUST return false when there is no more data to read.

Implementing stream decorators

Creating a stream decorator is very easy thanks to the GuzzleHttp\Psr7\StreamDecoratorTrait. This trait provides methods that implement Psr\Http\Message\StreamInterface by proxying to an underlying stream. Just use the StreamDecoratorTrait and implement your custom methods.

For example, let's say we wanted to call a specific function each time the last byte is read from a stream. This could be implemented by overriding the read() method.

use Psr\Http\Message\StreamInterface;
use GuzzleHttp\Psr7\StreamDecoratorTrait;

class EofCallbackStream implements StreamInterface
{
    use StreamDecoratorTrait;

    private $callback;

    private $stream;

    public function __construct(StreamInterface $stream, callable $cb)
    {
        $this->stream = $stream;
        $this->callback = $cb;
    }

    public function read($length)
    {
        $result = $this->stream->read($length);

        // Invoke the callback when EOF is hit.
        if ($this->eof()) {
            ($this->callback)();
        }

        return $result;
    }
}

This decorator could be added to any existing stream and used like so:

use GuzzleHttp\Psr7;

$original = Psr7\Utils::streamFor('foo');

$eofStream = new EofCallbackStream($original, function () {
    echo 'EOF!';
});

$eofStream->read(2);
$eofStream->read(1);
// echoes "EOF!"
$eofStream->seek(0);
$eofStream->read(3);
// echoes "EOF!"

PHP StreamWrapper

You can use the GuzzleHttp\Psr7\StreamWrapper class if you need to use a PSR-7 stream as a PHP stream resource.

Use the GuzzleHttp\Psr7\StreamWrapper::getResource() method to create a PHP stream from a PSR-7 stream.

use GuzzleHttp\Psr7\StreamWrapper;

$stream = GuzzleHttp\Psr7\Utils::streamFor('hello!');
$resource = StreamWrapper::getResource($stream);
echo fread($resource, 6); // outputs hello!

Static API

There are various static methods available under the GuzzleHttp\Psr7 namespace.

GuzzleHttp\Psr7\Message::toString

public static function toString(MessageInterface $message): string

Returns the string representation of an HTTP message.

$request = new GuzzleHttp\Psr7\Request('GET', 'http://example.com');
echo GuzzleHttp\Psr7\Message::toString($request);

GuzzleHttp\Psr7\Message::bodySummary

public static function bodySummary(MessageInterface $message, int $truncateAt = 120): string|null

Get a short summary of the message body.

Will return null if the response is not printable.

GuzzleHttp\Psr7\Message::rewindBody

public static function rewindBody(MessageInterface $message): void

Attempts to rewind a message body and throws an exception on failure.

The body of the message will only be rewound if a call to tell() returns a value other than 0.

GuzzleHttp\Psr7\Message::parseMessage

public static function parseMessage(string $message): array

Parses an HTTP message into an associative array.

The array contains the "start-line" key containing the start line of the message, "headers" key containing an associative array of header array values, and a "body" key containing the body of the message.

GuzzleHttp\Psr7\Message::parseRequestUri

public static function parseRequestUri(string $path, array $headers): string

Constructs a URI for an HTTP request message.

GuzzleHttp\Psr7\Message::parseRequest

public static function parseRequest(string $message): Request

Parses a request message string into a request object.

GuzzleHttp\Psr7\Message::parseResponse

public static function parseResponse(string $message): Response

Parses a response message string into a response object.

GuzzleHttp\Psr7\Header::parse

public static function parse(string|array $header): array

Parse an array of header values containing ";" separated data into an array of associative arrays representing the header key value pair data of the header. When a parameter does not contain a value, but just contains a key, this function will inject a key with a '' string value.

GuzzleHttp\Psr7\Header::splitList

public static function splitList(string|string[] $header): string[]

Splits a HTTP header defined to contain a comma-separated list into each individual value:

$knownEtags = Header::splitList($request->getHeader('if-none-match'));

Example headers include accept, cache-control and if-none-match.

GuzzleHttp\Psr7\Header::normalize (deprecated)

public static function normalize(string|array $header): array

Header::normalize() is deprecated in favor of Header::splitList() which performs the same operation with a cleaned up API and improved documentation.

Converts an array of header values that may contain comma separated headers into an array of headers with no comma separated values.

GuzzleHttp\Psr7\Query::parse

public static function parse(string $str, int|bool $urlEncoding = true): array

Parse a query string into an associative array.

If multiple values are found for the same key, the value of that key value pair will become an array. This function does not parse nested PHP style arrays into an associative array (e.g., foo[a]=1&foo[b]=2 will be parsed into ['foo[a]' => '1', 'foo[b]' => '2']).

GuzzleHttp\Psr7\Query::build

public static function build(array $params, int|false $encoding = PHP_QUERY_RFC3986, bool $treatBoolsAsInts = true): string

Build a query string from an array of key value pairs.

This function can use the return value of parse() to build a query string. This function does not modify the provided keys when an array is encountered (like http_build_query() would).

GuzzleHttp\Psr7\Utils::caselessRemove

public static function caselessRemove(iterable<string> $keys, $keys, array $data): array

Remove the items given by the keys, case insensitively from the data.

GuzzleHttp\Psr7\Utils::copyToStream

public static function copyToStream(StreamInterface $source, StreamInterface $dest, int $maxLen = -1): void

Copy the contents of a stream into another stream until the given number of bytes have been read.

GuzzleHttp\Psr7\Utils::copyToString

public static function copyToString(StreamInterface $stream, int $maxLen = -1): string

Copy the contents of a stream into a string until the given number of bytes have been read.

GuzzleHttp\Psr7\Utils::hash

public static function hash(StreamInterface $stream, string $algo, bool $rawOutput = false): string

Calculate a hash of a stream.

This method reads the entire stream to calculate a rolling hash, based on PHP's hash_init functions.

GuzzleHttp\Psr7\Utils::modifyRequest

public static function modifyRequest(RequestInterface $request, array $changes): RequestInterface

Clone and modify a request with the given changes.

This method is useful for reducing the number of clones needed to mutate a message.

• method: (string) Changes the HTTP method.
• set_headers: (array) Sets the given headers.
• remove_headers: (array) Remove the given headers.
• body: (mixed) Sets the given body.
• uri: (UriInterface) Set the URI.
• query: (string) Set the query string value of the URI.
• version: (string) Set the protocol version.

GuzzleHttp\Psr7\Utils::readLine

public static function readLine(StreamInterface $stream, ?int $maxLength = null): string

Read a line from the stream up to the maximum allowed buffer length.

GuzzleHttp\Psr7\Utils::redactUserInfo

public static function redactUserInfo(UriInterface $uri): UriInterface

Redact the password in the user info part of a URI.

GuzzleHttp\Psr7\Utils::streamFor

public static function streamFor(resource|string|null|int|float|bool|StreamInterface|callable|\Iterator $resource = '', array $options = []): StreamInterface

Create a new stream based on the input type.

Options is an associative array that can contain the following keys:

• metadata: Array of custom metadata.
• size: Size of the stream.

This method accepts the following $resource types:

• Psr\Http\Message\StreamInterface: Returns the value as-is.
• string: Creates a stream object that uses the given string as the contents.
• resource: Creates a stream object that wraps the given PHP stream resource.
• Iterator: If the provided value implements Iterator, then a read-only stream object will be created that wraps the given iterable. Each time the stream is read from, data from the iterator will fill a buffer and will be continuously called until the buffer is equal to the requested read size. Subsequent read calls will first read from the buffer and then call next on the underlying iterator until it is exhausted.
• object with __toString(): If the object has the __toString() method, the object will be cast to a string and then a stream will be returned that uses the string value.
• NULL: When null is passed, an empty stream object is returned.
• callable When a callable is passed, a read-only stream object will be created that invokes the given callable. The callable is invoked with the number of suggested bytes to read. The callable can return any number of bytes, but MUST return false when there is no more data to return. The stream object that wraps the callable will invoke the callable until the number of requested bytes are available. Any additional bytes will be buffered and used in subsequent reads.

$stream = GuzzleHttp\Psr7\Utils::streamFor('foo');
$stream = GuzzleHttp\Psr7\Utils::streamFor(fopen('/path/to/file', 'r'));

$generator = function ($bytes) {
    for ($i = 0; $i < $bytes; $i++) {
        yield ' ';
    }
}

$stream = GuzzleHttp\Psr7\Utils::streamFor($generator(100));

GuzzleHttp\Psr7\Utils::tryFopen

public static function tryFopen(string $filename, string $mode): resource

Safely opens a PHP stream resource using a filename.

When fopen fails, PHP normally raises a warning. This function adds an error handler that checks for errors and throws an exception instead.

GuzzleHttp\Psr7\Utils::tryGetContents

public static function tryGetContents(resource $stream): string

Safely gets the contents of a given stream.

When stream_get_contents fails, PHP normally raises a warning. This function adds an error handler that checks for errors and throws an exception instead.

GuzzleHttp\Psr7\Utils::uriFor

public static function uriFor(string|UriInterface $uri): UriInterface

Returns a UriInterface for the given value.

This function accepts a string or UriInterface and returns a UriInterface for the given value. If the value is already a UriInterface, it is returned as-is.

GuzzleHttp\Psr7\MimeType::fromFilename

public static function fromFilename(string $filename): string|null

Determines the mimetype of a file by looking at its extension.

GuzzleHttp\Psr7\MimeType::fromExtension

public static function fromExtension(string $extension): string|null

Maps a file extensions to a mimetype.

Upgrading from Function API

The static API was first introduced in 1.7.0, in order to mitigate problems with functions conflicting between global and local copies of the package. The function API was removed in 2.0.0. A migration table has been provided here for your convenience:

Original Function	Replacement Method
str	Message::toString
uri_for	Utils::uriFor
stream_for	Utils::streamFor
parse_header	Header::parse
normalize_header	Header::normalize
modify_request	Utils::modifyRequest
rewind_body	Message::rewindBody
try_fopen	Utils::tryFopen
copy_to_string	Utils::copyToString
copy_to_stream	Utils::copyToStream
hash	Utils::hash
readline	Utils::readLine
parse_request	Message::parseRequest
parse_response	Message::parseResponse
parse_query	Query::parse
build_query	Query::build
mimetype_from_filename	MimeType::fromFilename
mimetype_from_extension	MimeType::fromExtension
_parse_message	Message::parseMessage
_parse_request_uri	Message::parseRequestUri
get_message_body_summary	Message::bodySummary
_caseless_remove	Utils::caselessRemove

Additional URI Methods

Aside from the standard Psr\Http\Message\UriInterface implementation in form of the GuzzleHttp\Psr7\Uri class, this library also provides additional functionality when working with URIs as static methods.

URI Types

An instance of Psr\Http\Message\UriInterface can either be an absolute URI or a relative reference. An absolute URI has a scheme. A relative reference is used to express a URI relative to another URI, the base URI. Relative references can be divided into several forms according to RFC 3986 Section 4.2:

• network-path references, e.g. //example.com/path
• absolute-path references, e.g. /path
• relative-path references, e.g. subpath

The following methods can be used to identify the type of the URI.

GuzzleHttp\Psr7\Uri::isAbsolute

public static function isAbsolute(UriInterface $uri): bool

Whether the URI is absolute, i.e. it has a scheme.

GuzzleHttp\Psr7\Uri::isNetworkPathReference

public static function isNetworkPathReference(UriInterface $uri): bool

Whether the URI is a network-path reference. A relative reference that begins with two slash characters is termed an network-path reference.

GuzzleHttp\Psr7\Uri::isAbsolutePathReference

public static function isAbsolutePathReference(UriInterface $uri): bool

Whether the URI is a absolute-path reference. A relative reference that begins with a single slash character is termed an absolute-path reference.

GuzzleHttp\Psr7\Uri::isRelativePathReference

public static function isRelativePathReference(UriInterface $uri): bool

Whether the URI is a relative-path reference. A relative reference that does not begin with a slash character is termed a relative-path reference.

GuzzleHttp\Psr7\Uri::isSameDocumentReference

public static function isSameDocumentReference(UriInterface $uri, ?UriInterface $base = null): bool

Whether the URI is a same-document reference. A same-document reference refers to a URI that is, aside from its fragment component, identical to the base URI. When no base URI is given, only an empty URI reference (apart from its fragment) is considered a same-document reference.

URI Components

Additional methods to work with URI components.

GuzzleHttp\Psr7\Uri::isDefaultPort

public static function isDefaultPort(UriInterface $uri): bool

Whether the URI has the default port of the current scheme. Psr\Http\Message\UriInterface::getPort may return null or the standard port. This method can be used independently of the implementation.

GuzzleHttp\Psr7\Uri::composeComponents

public static function composeComponents($scheme, $authority, $path, $query, $fragment): string

Composes a URI reference string from its various components according to RFC 3986 Section 5.3. Usually this method does not need to be called manually but instead is used indirectly via Psr\Http\Message\UriInterface::__toString.

GuzzleHttp\Psr7\Uri::fromParts

public static function fromParts(array $parts): UriInterface

Creates a URI from a hash of parse_url components.

GuzzleHttp\Psr7\Uri::withQueryValue

public static function withQueryValue(UriInterface $uri, $key, $value): UriInterface

Creates a new URI with a specific query string value. Any existing query string values that exactly match the provided key are removed and replaced with the given key value pair. A value of null will set the query string key without a value, e.g. "key" instead of "key=value".

GuzzleHttp\Psr7\Uri::withQueryValues

public static function withQueryValues(UriInterface $uri, array $keyValueArray): UriInterface

Creates a new URI with multiple query string values. It has the same behavior as withQueryValue() but for an associative array of key => value.

GuzzleHttp\Psr7\Uri::withoutQueryValue

public static function withoutQueryValue(UriInterface $uri, $key): UriInterface

Creates a new URI with a specific query string value removed. Any existing query string values that exactly match the provided key are removed.

Cross-Origin Detection

GuzzleHttp\Psr7\UriComparator provides methods to determine if a modified URL should be considered cross-origin.

GuzzleHttp\Psr7\UriComparator::isCrossOrigin

public static function isCrossOrigin(UriInterface $original, UriInterface $modified): bool

Determines if a modified URL should be considered cross-origin with respect to an original URL.

Reference Resolution

GuzzleHttp\Psr7\UriResolver provides methods to resolve a URI reference in the context of a base URI according to RFC 3986 Section 5. This is for example also what web browsers do when resolving a link in a website based on the current request URI.

GuzzleHttp\Psr7\UriResolver::resolve

public static function resolve(UriInterface $base, UriInterface $rel): UriInterface

Converts the relative URI into a new URI that is resolved against the base URI.

GuzzleHttp\Psr7\UriResolver::removeDotSegments

public static function removeDotSegments(string $path): string

Removes dot segments from a path and returns the new path according to RFC 3986 Section 5.2.4.

GuzzleHttp\Psr7\UriResolver::relativize

public static function relativize(UriInterface $base, UriInterface $target): UriInterface

Returns the target URI as a relative reference from the base URI. This method is the counterpart to resolve():

(string) $target === (string) UriResolver::resolve($base, UriResolver::relativize($base, $target))

One use-case is to use the current request URI as base URI and then generate relative links in your documents to reduce the document size or offer self-contained downloadable document archives.

$base = new Uri('http://example.com/a/b/');
echo UriResolver::relativize($base, new Uri('http://example.com/a/b/c'));  // prints 'c'.
echo UriResolver::relativize($base, new Uri('http://example.com/a/x/y'));  // prints '../x/y'.
echo UriResolver::relativize($base, new Uri('http://example.com/a/b/?q')); // prints '?q'.
echo UriResolver::relativize($base, new Uri('http://example.org/a/b/'));   // prints '//example.org/a/b/'.

Normalization and Comparison

GuzzleHttp\Psr7\UriNormalizer provides methods to normalize and compare URIs according to RFC 3986 Section 6.

GuzzleHttp\Psr7\UriNormalizer::normalize

public static function normalize(UriInterface $uri, $flags = self::PRESERVING_NORMALIZATIONS): UriInterface

Returns a normalized URI. The scheme and host component are already normalized to lowercase per PSR-7 UriInterface. This methods adds additional normalizations that can be configured with the $flags parameter which is a bitmask of normalizations to apply. The following normalizations are available:

• UriNormalizer::PRESERVING_NORMALIZATIONS

  Default normalizations which only include the ones that preserve semantics.

• UriNormalizer::CAPITALIZE_PERCENT_ENCODING

  All letters within a percent-encoding triplet (e.g., "%3A") are case-insensitive, and should be capitalized.

  Example: http://example.org/a%c2%b1b → http://example.org/a%C2%B1b

• UriNormalizer::DECODE_UNRESERVED_CHARACTERS

  Decodes percent-encoded octets of unreserved characters. For consistency, percent-encoded octets in the ranges of ALPHA (%41–%5A and %61–%7A), DIGIT (%30–%39), hyphen (%2D), period (%2E), underscore (%5F), or tilde (%7E) should not be created by URI producers and, when found in a URI, should be decoded to their corresponding unreserved characters by URI normalizers.

  Example: http://example.org/%7Eusern%61me/ → http://example.org/~username/

• UriNormalizer::CONVERT_EMPTY_PATH

  Converts the empty path to "/" for http and https URIs.

  Example: http://example.org → http://example.org/

• UriNormalizer::REMOVE_DEFAULT_HOST

  Removes the default host of the given URI scheme from the URI. Only the "file" scheme defines the default host "localhost". All of file:/myfile, file:///myfile, and file://localhost/myfile are equivalent according to RFC 3986.

  Example: file://localhost/myfile → file:///myfile

• UriNormalizer::REMOVE_DEFAULT_PORT

  Removes the default port of the given URI scheme from the URI.

  Example: http://example.org:80/ → http://example.org/

• UriNormalizer::REMOVE_DOT_SEGMENTS

  Removes unnecessary dot-segments. Dot-segments in relative-path references are not removed as it would change the semantics of the URI reference.

  Example: http://example.org/../a/b/../c/./d.html → http://example.org/a/c/d.html

• UriNormalizer::REMOVE_DUPLICATE_SLASHES

  Paths which include two or more adjacent slashes are converted to one. Webservers usually ignore duplicate slashes and treat those URIs equivalent. But in theory those URIs do not need to be equivalent. So this normalization may change the semantics. Encoded slashes (%2F) are not removed.

  Example: http://example.org//foo///bar.html → http://example.org/foo/bar.html

• UriNormalizer::SORT_QUERY_PARAMETERS

  Sort query parameters with their values in alphabetical order. However, the order of parameters in a URI may be significant (this is not defined by the standard). So this normalization is not safe and may change the semantics of the URI.

  Example: ?lang=en&article=fred → ?article=fred&lang=en

GuzzleHttp\Psr7\UriNormalizer::isEquivalent

public static function isEquivalent(UriInterface $uri1, UriInterface $uri2, $normalizations = self::PRESERVING_NORMALIZATIONS): bool

Whether two URIs can be considered equivalent. Both URIs are normalized automatically before comparison with the given $normalizations bitmask. The method also accepts relative URI references and returns true when they are equivalent. This of course assumes they will be resolved against the same base URI. If this is not the case, determination of equivalence or difference of relative references does not mean anything.

Security

If you discover a security vulnerability within this package, please send an email to security@tidelift.com. All security vulnerabilities will be promptly addressed. Please do not disclose security-related issues publicly until a fix has been announced. Please see Security Policy for more information.

License

Guzzle is made available under the MIT License (MIT). Please see License File for more information.

For Enterprise

Available as part of the Tidelift Subscription

The maintainers of Guzzle and thousands of other packages are working with Tidelift to deliver commercial support and maintenance for the open source dependencies you use to build your applications. Save time, reduce risk, and improve code health, while paying the maintainers of the exact dependencies you use. Learn more.