browser.php

<?php
/**
 *  Base include file for SimpleTest
 *  @package    SimpleTest
 *  @subpackage WebTester
 *  @version    $Id$
 */

/**#@+
 *  include other SimpleTest class files
 */
require_once(dirname(__FILE__) . '/simpletest.php');
require_once(dirname(__FILE__) . '/http.php');
require_once(dirname(__FILE__) . '/encoding.php');
require_once(dirname(__FILE__) . '/page.php');
require_once(dirname(__FILE__) . '/php_parser.php');
require_once(dirname(__FILE__) . '/tidy_parser.php');
require_once(dirname(__FILE__) . '/selector.php');
require_once(dirname(__FILE__) . '/frames.php');
require_once(dirname(__FILE__) . '/user_agent.php');
if (! SimpleTest::getParsers()) {
    SimpleTest::setParsers(array(new SimpleTidyPageBuilder(), new SimplePHPPageBuilder()));
    //SimpleTest::setParsers(array(new SimplePHPPageBuilder()));
}
/**#@-*/

if (! defined('DEFAULT_MAX_NESTED_FRAMES')) {
    define('DEFAULT_MAX_NESTED_FRAMES', 3);
}

/**
 *    Browser history list.
 *    @package SimpleTest
 *    @subpackage WebTester
 */
class SimpleBrowserHistory {
    private $sequence = array();
    private $position = -1;

    /**
     *    Test for no entries yet.
     *    @return boolean        True if empty.
     *    @access private
     */
    protected function isEmpty() {
        return ($this->position == -1);
    }

    /**
     *    Test for being at the beginning.
     *    @return boolean        True if first.
     *    @access private
     */
    protected function atBeginning() {
        return ($this->position == 0) && ! $this->isEmpty();
    }

    /**
     *    Test for being at the last entry.
     *    @return boolean        True if last.
     *    @access private
     */
    protected function atEnd() {
        return ($this->position + 1 >= count($this->sequence)) && ! $this->isEmpty();
    }

    /**
     *    Adds a successfully fetched page to the history.
     *    @param SimpleUrl $url                 URL of fetch.
     *    @param SimpleEncoding $parameters     Any post data with the fetch.
     *    @access public
     */
    function recordEntry($url, $parameters) {
        $this->dropFuture();
        array_push(
                $this->sequence,
                array('url' => $url, 'parameters' => $parameters));
        $this->position++;
    }

    /**
     *    Last fully qualified URL for current history
     *    position.
     *    @return SimpleUrl        URL for this position.
     *    @access public
     */
    function getUrl() {
        if ($this->isEmpty()) {
            return false;
        }
        return $this->sequence[$this->position]['url'];
    }

    /**
     *    Parameters of last fetch from current history
     *    position.
     *    @return SimpleFormEncoding    Post parameters.
     *    @access public
     */
    function getParameters() {
        if ($this->isEmpty()) {
            return false;
        }
        return $this->sequence[$this->position]['parameters'];
    }

    /**
     *    Step back one place in the history. Stops at
     *    the first page.
     *    @return boolean     True if any previous entries.
     *    @access public
     */
    function back() {
        if ($this->isEmpty() || $this->atBeginning()) {
            return false;
        }
        $this->position--;
        return true;
    }

    /**
     *    Step forward one place. If already at the
     *    latest entry then nothing will happen.
     *    @return boolean     True if any future entries.
     *    @access public
     */
    function forward() {
        if ($this->isEmpty() || $this->atEnd()) {
            return false;
        }
        $this->position++;
        return true;
    }

    /**
     *    Ditches all future entries beyond the current
     *    point.
     *    @access private
     */
    protected function dropFuture() {
        if ($this->isEmpty()) {
            return;
        }
        while (! $this->atEnd()) {
            array_pop($this->sequence);
        }
    }
}

/**
 *    Simulated web browser. This is an aggregate of
 *    the user agent, the HTML parsing, request history
 *    and the last header set.
 *    @package SimpleTest
 *    @subpackage WebTester
 */
class SimpleBrowser {
    private $user_agent;
    private $page;
    private $history;
    private $ignore_frames;
    private $maximum_nested_frames;
    private $parser;

    /**
     *    Starts with a fresh browser with no
     *    cookie or any other state information. The
     *    exception is that a default proxy will be
     *    set up if specified in the options.
     *    @access public
     */
    function __construct() {
        $this->user_agent = $this->createUserAgent();
        $this->user_agent->useProxy(
                SimpleTest::getDefaultProxy(),
                SimpleTest::getDefaultProxyUsername(),
                SimpleTest::getDefaultProxyPassword());
        $this->page = new SimplePage();
        $this->history = $this->createHistory();
        $this->ignore_frames = false;
        $this->maximum_nested_frames = DEFAULT_MAX_NESTED_FRAMES;
    }

    /**
     *    Creates the underlying user agent.
     *    @return SimpleFetcher    Content fetcher.
     *    @access protected
     */
    protected function createUserAgent() {
        return new SimpleUserAgent();
    }

    /**
     *    Creates a new empty history list.
     *    @return SimpleBrowserHistory    New list.
     *    @access protected
     */
    protected function createHistory() {
        return new SimpleBrowserHistory();
    }

    /**
     *    Get the HTML parser to use. Can be overridden by
     *    setParser. Otherwise scans through the available parsers and
     *    uses the first one which is available.
     *    @return object SimplePHPPageBuilder or SimpleTidyPageBuilder
     */
    protected function getParser() {
        if ($this->parser) {
            return $this->parser;
        }
        foreach (SimpleTest::getParsers() as $parser) {
            if ($parser->can()) {
                return $parser;
            }
        }
    }

    /**
     *    Override the default HTML parser, allowing parsers to be plugged in.
     *    @param object           A parser object instance.
     */
    public function setParser($parser) {
        $this->parser = $parser;
    }

    /**
     *    Disables frames support. Frames will not be fetched
     *    and the frameset page will be used instead.
     *    @access public
     */
    function ignoreFrames() {
        $this->ignore_frames = true;
    }

    /**
     *    Enables frames support. Frames will be fetched from
     *    now on.
     *    @access public
     */
    function useFrames() {
        $this->ignore_frames = false;
    }

    /**
     *    Switches off cookie sending and recieving.
     *    @access public
     */
    function ignoreCookies() {
        $this->user_agent->ignoreCookies();
    }

    /**
     *    Switches back on the cookie sending and recieving.
     *    @access public
     */
    function useCookies() {
        $this->user_agent->useCookies();
    }

    /**
     *    Parses the raw content into a page. Will load further
     *    frame pages unless frames are disabled.
     *    @param SimpleHttpResponse $response    Response from fetch.
     *    @param integer $depth                  Nested frameset depth.
     *    @return SimplePage                     Parsed HTML.
     *    @access private
     */
    protected function parse($response, $depth = 0) {
        $page = $this->buildPage($response);
        if ($this->ignore_frames || ! $page->hasFrames() || ($depth > $this->maximum_nested_frames)) {
            return $page;
        }
        $frameset = new SimpleFrameset($page);
        foreach ($page->getFrameset() as $key => $url) {
            $frame = $this->fetch($url, new SimpleGetEncoding(), $depth + 1);
            $frameset->addFrame($frame, $key);
        }
        return $frameset;
    }

    /**
     *    Assembles the parsing machinery and actually parses
     *    a single page. Frees all of the builder memory and so
     *    unjams the PHP memory management.
     *    @param SimpleHttpResponse $response    Response from fetch.
     *    @return SimplePage                     Parsed top level page.
     */
    protected function buildPage($response) {
        return $this->getParser()->parse($response);
    }

    /**
     *    Fetches a page. Jointly recursive with the parse()
     *    method as it descends a frameset.
     *    @param string/SimpleUrl $url          Target to fetch.
     *    @param SimpleEncoding $encoding       GET/POST parameters.
     *    @param integer $depth                 Nested frameset depth protection.
     *    @return SimplePage                    Parsed page.
     *    @access private
     */
    protected function fetch($url, $encoding, $depth = 0) {
        $response = $this->user_agent->fetchResponse($url, $encoding);
        if ($response->isError()) {
            return new SimplePage($response);
        }
        return $this->parse($response, $depth);
    }

    /**
     *    Fetches a page or a single frame if that is the current
     *    focus.
     *    @param SimpleUrl $url                   Target to fetch.
     *    @param SimpleEncoding $parameters       GET/POST parameters.
     *    @return string                          Raw content of page.
     *    @access private
     */
    protected function load($url, $parameters) {
        $frame = $url->getTarget();
        if (! $frame || ! $this->page->hasFrames() || (strtolower($frame) == '_top')) {
            return $this->loadPage($url, $parameters);
        }
        return $this->loadFrame(array($frame), $url, $parameters);
    }

    /**
     *    Fetches a page and makes it the current page/frame.
     *    @param string/SimpleUrl $url            Target to fetch as string.
     *    @param SimplePostEncoding $parameters   POST parameters.
     *    @return string                          Raw content of page.
     *    @access private
     */
    protected function loadPage($url, $parameters) {
        $this->page = $this->fetch($url, $parameters);
        $this->history->recordEntry(
                $this->page->getUrl(),
                $this->page->getRequestData());
        return $this->page->getRaw();
    }

    /**
     *    Fetches a frame into the existing frameset replacing the
     *    original.
     *    @param array $frames                    List of names to drill down.
     *    @param string/SimpleUrl $url            Target to fetch as string.
     *    @param SimpleFormEncoding $parameters   POST parameters.
     *    @return string                          Raw content of page.
     *    @access private
     */
    protected function loadFrame($frames, $url, $parameters) {
        $page = $this->fetch($url, $parameters);
        $this->page->setFrame($frames, $page);
        return $page->getRaw();
    }

    /**
     *    Removes expired and temporary cookies as if
     *    the browser was closed and re-opened.
     *    @param string/integer $date   Time when session restarted.
     *                                  If omitted then all persistent
     *                                  cookies are kept.
     *    @access public
     */
    function restart($date = false) {
        $this->user_agent->restart($date);
    }

    /**
     *    Adds a header to every fetch.
     *    @param string $header       Header line to add to every
     *                                request until cleared.
     *    @access public
     */
    function addHeader($header) {
        $this->user_agent->addHeader($header);
    }

    /**
     *    Ages the cookies by the specified time.
     *    @param integer $interval    Amount in seconds.
     *    @access public
     */
    function ageCookies($interval) {
        $this->user_agent->ageCookies($interval);
    }

    /**
     *    Sets an additional cookie. If a cookie has
     *    the same name and path it is replaced.
     *    @param string $name       Cookie key.
     *    @param string $value      Value of cookie.
     *    @param string $host       Host upon which the cookie is valid.
     *    @param string $path       Cookie path if not host wide.
     *    @param string $expiry     Expiry date.
     *    @access public
     */
    function setCookie($name, $value, $host = false, $path = '/', $expiry = false) {
        $this->user_agent->setCookie($name, $value, $host, $path, $expiry);
    }

    /**
     *    Reads the most specific cookie value from the
     *    browser cookies.
     *    @param string $host        Host to search.
     *    @param string $path        Applicable path.
     *    @param string $name        Name of cookie to read.
     *    @return string             False if not present, else the
     *                               value as a string.
     *    @access public
     */
    function getCookieValue($host, $path, $name) {
        return $this->user_agent->getCookieValue($host, $path, $name);
    }

    /**
     *    Reads the current cookies for the current URL.
     *    @param string $name   Key of cookie to find.
     *    @return string        Null if there is no current URL, false
     *                          if the cookie is not set.
     *    @access public
     */
    function getCurrentCookieValue($name) {
        return $this->user_agent->getBaseCookieValue($name, $this->page->getUrl());
    }

    /**
     *    Sets the maximum number of redirects before
     *    a page will be loaded anyway.
     *    @param integer $max        Most hops allowed.
     *    @access public
     */
    function setMaximumRedirects($max) {
        $this->user_agent->setMaximumRedirects($max);
    }

    /**
     *    Sets the maximum number of nesting of framed pages
     *    within a framed page to prevent loops.
     *    @param integer $max        Highest depth allowed.
     *    @access public
     */
    function setMaximumNestedFrames($max) {
        $this->maximum_nested_frames = $max;
    }

    /**
     *    Sets the socket timeout for opening a connection.
     *    @param integer $timeout      Maximum time in seconds.
     *    @access public
     */
    function setConnectionTimeout($timeout) {
        $this->user_agent->setConnectionTimeout($timeout);
    }

    /**
     *    Sets proxy to use on all requests for when
     *    testing from behind a firewall. Set URL
     *    to false to disable.
     *    @param string $proxy        Proxy URL.
     *    @param string $username     Proxy username for authentication.
     *    @param string $password     Proxy password for authentication.
     *    @access public
     */
    function useProxy($proxy, $username = false, $password = false) {
        $this->user_agent->useProxy($proxy, $username, $password);
    }

    /**
     *    Fetches the page content with a HEAD request.
     *    Will affect cookies, but will not change the base URL.
     *    @param string/SimpleUrl $url                Target to fetch as string.
     *    @param hash/SimpleHeadEncoding $parameters  Additional parameters for
     *                                                HEAD request.
     *    @return boolean                             True if successful.
     *    @access public
     */
    function head($url, $parameters = false) {
        if (! is_object($url)) {
            $url = new SimpleUrl($url);
        }
        if ($this->getUrl()) {
            $url = $url->makeAbsolute($this->getUrl());
        }
        $response = $this->user_agent->fetchResponse($url, new SimpleHeadEncoding($parameters));
        $this->page = new SimplePage($response);
        return ! $response->isError();
    }

    /**
     *    Fetches the page content with a simple GET request.
     *    @param string/SimpleUrl $url                Target to fetch.
     *    @param hash/SimpleFormEncoding $parameters  Additional parameters for
     *                                                GET request.
     *    @return string                              Content of page or false.
     *    @access public
     */
    function get($url, $parameters = false) {
        if (! is_object($url)) {
            $url = new SimpleUrl($url);
        }
        if ($this->getUrl()) {
            $url = $url->makeAbsolute($this->getUrl());
        }
        return $this->load($url, new SimpleGetEncoding($parameters));
    }

    /**
     *    Fetches the page content with a POST request.
     *    @param string/SimpleUrl $url                Target to fetch as string.
     *    @param hash/SimpleFormEncoding $parameters  POST parameters or request body.
     *    @param string $content_type                 MIME Content-Type of the request body
     *    @return string                              Content of page.
     *    @access public
     */
    function post($url, $parameters = false, $content_type = false) {
        if (! is_object($url)) {
            $url = new SimpleUrl($url);
        }
        if ($this->getUrl()) {
            $url = $url->makeAbsolute($this->getUrl());
        }
        return $this->load($url, new SimplePostEncoding($parameters, $content_type));
    }

    /**
     *    Fetches the page content with a PUT request.
     *    @param string/SimpleUrl $url                Target to fetch as string.
     *    @param hash/SimpleFormEncoding $parameters  PUT request body.
     *    @param string $content_type                 MIME Content-Type of the request body
     *    @return string                              Content of page.
     *    @access public
     */
    function put($url, $parameters = false, $content_type = false) {
        if (! is_object($url)) {
            $url = new SimpleUrl($url);
        }
        return $this->load($url, new SimplePutEncoding($parameters, $content_type));
    }

    /**
     *    Sends a DELETE request and fetches the response.
     *    @param string/SimpleUrl $url                Target to fetch.
     *    @param hash/SimpleFormEncoding $parameters  Additional parameters for
     *                                                DELETE request.
     *    @return string                              Content of page or false.
     *    @access public
     */
    function delete($url, $parameters = false) {
        if (! is_object($url)) {
            $url = new SimpleUrl($url);
        }
        return $this->load($url, new SimpleDeleteEncoding($parameters));
    }

    /**
     *    Equivalent to hitting the retry button on the
     *    browser. Will attempt to repeat the page fetch. If
     *    there is no history to repeat it will give false.
     *    @return string/boolean   Content if fetch succeeded
     *                             else false.
     *    @access public
     */
    function retry() {
        $frames = $this->page->getFrameFocus();
        if (count($frames) > 0) {
            $this->loadFrame(
                    $frames,
                    $this->page->getUrl(),
                    $this->page->getRequestData());
            return $this->page->getRaw();
        }
        if ($url = $this->history->getUrl()) {
            $this->page = $this->fetch($url, $this->history->getParameters());
            return $this->page->getRaw();
        }
        return false;
    }

    /**
     *    Equivalent to hitting the back button on the
     *    browser. The browser history is unchanged on
     *    failure. The page content is refetched as there
     *    is no concept of content caching in SimpleTest.
     *    @return boolean     True if history entry and
     *                        fetch succeeded
     *    @access public
     */
    function back() {
        if (! $this->history->back()) {
            return false;
        }
        $content = $this->retry();
        if (! $content) {
            $this->history->forward();
        }
        return $content;
    }

    /**
     *    Equivalent to hitting the forward button on the
     *    browser. The browser history is unchanged on
     *    failure. The page content is refetched as there
     *    is no concept of content caching in SimpleTest.
     *    @return boolean     True if history entry and
     *                        fetch succeeded
     *    @access public
     */
    function forward() {
        if (! $this->history->forward()) {
            return false;
        }
        $content = $this->retry();
        if (! $content) {
            $this->history->back();
        }
        return $content;
    }

    /**
     *    Retries a request after setting the authentication
     *    for the current realm.
     *    @param string $username    Username for realm.
     *    @param string $password    Password for realm.
     *    @return boolean            True if successful fetch. Note
     *                               that authentication may still have
     *                               failed.
     *    @access public
     */
    function authenticate($username, $password) {
        if (! $this->page->getRealm()) {
            return false;
        }
        $url = $this->page->getUrl();
        if (! $url) {
            return false;
        }
        $this->user_agent->setIdentity(
                $url->getHost(),
                $this->page->getRealm(),
                $username,
                $password);
        return $this->retry();
    }

    /**
     *    Accessor for a breakdown of the frameset.
     *    @return array   Hash tree of frames by name
     *                    or index if no name.
     *    @access public
     */
    function getFrames() {
        return $this->page->getFrames();
    }

    /**
     *    Accessor for current frame focus. Will be
     *    false if no frame has focus.
     *    @return integer/string/boolean    Label if any, otherwise
     *                                      the position in the frameset
     *                                      or false if none.
     *    @access public
     */
    function getFrameFocus() {
        return $this->page->getFrameFocus();
    }

    /**
     *    Sets the focus by index. The integer index starts from 1.
     *    @param integer $choice    Chosen frame.
     *    @return boolean           True if frame exists.
     *    @access public
     */
    function setFrameFocusByIndex($choice) {
        return $this->page->setFrameFocusByIndex($choice);
    }

    /**
     *    Sets the focus by name.
     *    @param string $name    Chosen frame.
     *    @return boolean        True if frame exists.
     *    @access public
     */
    function setFrameFocus($name) {
        return $this->page->setFrameFocus($name);
    }

    /**
     *    Clears the frame focus. All frames will be searched
     *    for content.
     *    @access public
     */
    function clearFrameFocus() {
        return $this->page->clearFrameFocus();
    }

    /**
     *    Accessor for last error.
     *    @return string        Error from last response.
     *    @access public
     */
    function getTransportError() {
        return $this->page->getTransportError();
    }

    /**
     *    Accessor for current MIME type.
     *    @return string    MIME type as string; e.g. 'text/html'
     *    @access public
     */
    function getMimeType() {
        return $this->page->getMimeType();
    }

    /**
     *    Accessor for last response code.
     *    @return integer    Last HTTP response code received.
     *    @access public
     */
    function getResponseCode() {
        return $this->page->getResponseCode();
    }

    /**
     *    Accessor for last Authentication type. Only valid
     *    straight after a challenge (401).
     *    @return string    Description of challenge type.
     *    @access public
     */
    function getAuthentication() {
        return $this->page->getAuthentication();
    }

    /**
     *    Accessor for last Authentication realm. Only valid
     *    straight after a challenge (401).
     *    @return string    Name of security realm.
     *    @access public
     */
    function getRealm() {
        return $this->page->getRealm();
    }

    /**
     *    Accessor for current URL of page or frame if
     *    focused.
     *    @return string    Location of current page or frame as
     *                      a string.
     */
    function getUrl() {
        $url = $this->page->getUrl();
        return $url ? $url->asString() : false;
    }

    /**
     *    Accessor for base URL of page if set via BASE tag
     *    @return string    base URL
     */
    function getBaseUrl() {
        $url = $this->page->getBaseUrl();
        return $url ? $url->asString() : false;
    }

    /**
     *    Accessor for raw bytes sent down the wire.
     *    @return string      Original text sent.
     *    @access public
     */
    function getRequest() {
        return $this->page->getRequest();
    }

    /**
     *    Accessor for raw header information.
     *    @return string      Header block.
     *    @access public
     */
    function getHeaders() {
        return $this->page->getHeaders();
    }

    /**
     *    Accessor for raw page information.
     *    @return string      Original text content of web page.
     *    @access public
     */
    function getContent() {
        return $this->page->getRaw();
    }

    /**
     *    Accessor for plain text version of the page.
     *    @return string      Normalised text representation.
     *    @access public
     */
    function getContentAsText() {
        return $this->page->getText();
    }

    /**
     *    Accessor for parsed title.
     *    @return string     Title or false if no title is present.
     *    @access public
     */
    function getTitle() {
        return $this->page->getTitle();
    }

    /**
     *    Accessor for a list of all links in current page.
     *    @return array   List of urls with scheme of
     *                    http or https and hostname.
     *    @access public
     */
    function getUrls() {
        return $this->page->getUrls();
    }

    /**
     *    Sets all form fields with that name.
     *    @param string $label   Name or label of field in forms.
     *    @param string $value   New value of field.
     *    @return boolean        True if field exists, otherwise false.
     *    @access public
     */
    function setField($label, $value, $position=false) {
        return $this->page->setField(new SimpleByLabelOrName($label), $value, $position);
    }

    /**
     *    Sets all form fields with that name. Will use label if
     *    one is available (not yet implemented).
     *    @param string $name    Name of field in forms.
     *    @param string $value   New value of field.
     *    @return boolean        True if field exists, otherwise false.
     *    @access public
     */
    function setFieldByName($name, $value, $position=false) {
        return $this->page->setField(new SimpleByName($name), $value, $position);
    }

    /**
     *    Sets all form fields with that id attribute.
     *    @param string/integer $id   Id of field in forms.
     *    @param string $value        New value of field.
     *    @return boolean             True if field exists, otherwise false.
     *    @access public
     */
    function setFieldById($id, $value) {
        return $this->page->setField(new SimpleById($id), $value);
    }

    /**
     *    Accessor for a form element value within the page.
     *    Finds the first match.
     *    @param string $label       Field label.
     *    @return string/boolean     A value if the field is
     *                               present, false if unchecked
     *                               and null if missing.
     *    @access public
     */
    function getField($label) {
        return $this->page->getField(new SimpleByLabelOrName($label));
    }

    /**
     *    Accessor for a form element value within the page.
     *    Finds the first match.
     *    @param string $name        Field name.
     *    @return string/boolean     A string if the field is
     *                               present, false if unchecked
     *                               and null if missing.
     *    @access public
     */
    function getFieldByName($name) {
        return $this->page->getField(new SimpleByName($name));
    }

    /**
     *    Accessor for a form element value within the page.
     *    @param string/integer $id  Id of field in forms.
     *    @return string/boolean     A string if the field is
     *                               present, false if unchecked
     *                               and null if missing.
     *    @access public
     */
    function getFieldById($id) {
        return $this->page->getField(new SimpleById($id));
    }

    /**
     *    Clicks the submit button by label. The owning
     *    form will be submitted by this.
     *    @param string $label    Button label. An unlabeled
     *                            button can be triggered by 'Submit'.
     *    @param hash $additional Additional form data.
     *    @return string/boolean  Page on success.
     *    @access public
     */
    function clickSubmit($label = 'Submit', $additional = false) {
        if (! ($form = $this->page->getFormBySubmit(new SimpleByLabel($label)))) {
            return false;
        }
        $success = $this->load(
                $form->getAction(),
                $form->submitButton(new SimpleByLabel($label), $additional));
        return ($success ? $this->getContent() : $success);
    }

    /**
     *    Clicks the submit button by name attribute. The owning
     *    form will be submitted by this.
     *    @param string $name     Button name.
     *    @param hash $additional Additional form data.
     *    @return string/boolean  Page on success.
     *    @access public
     */
    function clickSubmitByName($name, $additional = false) {
        if (! ($form = $this->page->getFormBySubmit(new SimpleByName($name)))) {
            return false;
        }
        $success = $this->load(
                $form->getAction(),
                $form->submitButton(new SimpleByName($name), $additional));
        return ($success ? $this->getContent() : $success);
    }

    /**
     *    Clicks the submit button by ID attribute of the button
     *    itself. The owning form will be submitted by this.
     *    @param string $id       Button ID.
     *    @param hash $additional Additional form data.
     *    @return string/boolean  Page on success.
     *    @access public
     */
    function clickSubmitById($id, $additional = false) {
        if (! ($form = $this->page->getFormBySubmit(new SimpleById($id)))) {
            return false;
        }
        $success = $this->load(
                $form->getAction(),
                $form->submitButton(new SimpleById($id), $additional));
        return ($success ? $this->getContent() : $success);
    }

    /**
     *    Tests to see if a submit button exists with this
     *    label.
     *    @param string $label    Button label.
     *    @return boolean         True if present.
     *    @access public
     */
    function isSubmit($label) {
        return (boolean)$this->page->getFormBySubmit(new SimpleByLabel($label));
    }

    /**
     *    Clicks the submit image by some kind of label. Usually
     *    the alt tag or the nearest equivalent. The owning
     *    form will be submitted by this. Clicking outside of
     *    the boundary of the coordinates will result in
     *    a failure.
     *    @param string $label    ID attribute of button.
     *    @param integer $x       X-coordinate of imaginary click.
     *    @param integer $y       Y-coordinate of imaginary click.
     *    @param hash $additional Additional form data.
     *    @return string/boolean  Page on success.
     *    @access public
     */
    function clickImage($label, $x = 1, $y = 1, $additional = false) {
        if (! ($form = $this->page->getFormByImage(new SimpleByLabel($label)))) {
            return false;
        }
        $success = $this->load(
                $form->getAction(),
                $form->submitImage(new SimpleByLabel($label), $x, $y, $additional));
        return ($success ? $this->getContent() : $success);
    }

    /**
     *    Clicks the submit image by the name. Usually
     *    the alt tag or the nearest equivalent. The owning
     *    form will be submitted by this. Clicking outside of
     *    the boundary of the coordinates will result in
     *    a failure.
     *    @param string $name     Name attribute of button.
     *    @param integer $x       X-coordinate of imaginary click.
     *    @param integer $y       Y-coordinate of imaginary click.
     *    @param hash $additional Additional form data.
     *    @return string/boolean  Page on success.
     *    @access public
     */
    function clickImageByName($name, $x = 1, $y = 1, $additional = false) {
        if (! ($form = $this->page->getFormByImage(new SimpleByName($name)))) {
            return false;
        }
        $success = $this->load(
                $form->getAction(),
                $form->submitImage(new SimpleByName($name), $x, $y, $additional));
        return ($success ? $this->getContent() : $success);
    }

    /**
     *    Clicks the submit image by ID attribute. The owning
     *    form will be submitted by this. Clicking outside of
     *    the boundary of the coordinates will result in
     *    a failure.
     *    @param integer/string $id    ID attribute of button.
     *    @param integer $x            X-coordinate of imaginary click.
     *    @param integer $y            Y-coordinate of imaginary click.
     *    @param hash $additional      Additional form data.
     *    @return string/boolean       Page on success.
     *    @access public
     */
    function clickImageById($id, $x = 1, $y = 1, $additional = false) {
        if (! ($form = $this->page->getFormByImage(new SimpleById($id)))) {
            return false;
        }
        $success = $this->load(
                $form->getAction(),
                $form->submitImage(new SimpleById($id), $x, $y, $additional));
        return ($success ? $this->getContent() : $success);
    }

    /**
     *    Tests to see if an image exists with this
     *    title or alt text.
     *    @param string $label    Image text.
     *    @return boolean         True if present.
     *    @access public
     */
    function isImage($label) {
        return (boolean)$this->page->getFormByImage(new SimpleByLabel($label));
    }

    /**
     *    Submits a form by the ID.
     *    @param string $id       The form ID. No submit button value
     *                            will be sent.
     *    @return string/boolean  Page on success.
     *    @access public
     */
    function submitFormById($id, $additional = false) {
        if (! ($form = $this->page->getFormById($id))) {
            return false;
        }
        $success = $this->load(
                $form->getAction(),
                $form->submit($additional));
        return ($success ? $this->getContent() : $success);
    }

    /**
     *    Finds a URL by label. Will find the first link
     *    found with this link text by default, or a later
     *    one if an index is given. The match ignores case and
     *    white space issues.
     *    @param string $label     Text between the anchor tags.
     *    @param integer $index    Link position counting from zero.
     *    @return string/boolean   URL on success.
     *    @access public
     */
    function getLink($label, $index = 0) {
        $urls = $this->page->getUrlsByLabel($label);
        if (count($urls) == 0) {
            return false;
        }
        if (count($urls) < $index + 1) {
            return false;
        }
        return $urls[$index];
    }

    /**
     *    Follows a link by label. Will click the first link
     *    found with this link text by default, or a later
     *    one if an index is given. The match ignores case and
     *    white space issues.
     *    @param string $label     Text between the anchor tags.
     *    @param integer $index    Link position counting from zero.
     *    @return string/boolean   Page on success.
     *    @access public
     */
    function clickLink($label, $index = 0) {
        $url = $this->getLink($label, $index);
        if ($url === false) {
            return false;
        }
        $this->load($url, new SimpleGetEncoding());
        return $this->getContent();
    }

    /**
     *    Finds a link by id attribute.
     *    @param string $id        ID attribute value.
     *    @return string/boolean   URL on success.
     *    @access public
     */
    function getLinkById($id) {
        return $this->page->getUrlById($id);
    }

    /**
     *    Follows a link by id attribute.
     *    @param string $id        ID attribute value.
     *    @return string/boolean   Page on success.
     *    @access public
     */
    function clickLinkById($id) {
        if (! ($url = $this->getLinkById($id))) {
            return false;
        }
        $this->load($url, new SimpleGetEncoding());
        return $this->getContent();
    }

    /**
     *    Clicks a visible text item. Will first try buttons,
     *    then links and then images.
     *    @param string $label        Visible text or alt text.
     *    @return string/boolean      Raw page or false.
     *    @access public
     */
    function click($label) {
        $raw = $this->clickSubmit($label);
        if (! $raw) {
            $raw = $this->clickLink($label);
        }
        if (! $raw) {
            $raw = $this->clickImage($label);
        }
        return $raw;
    }

    /**
     *    Tests to see if a click target exists.
     *    @param string $label    Visible text or alt text.
     *    @return boolean         True if target present.
     *    @access public
     */
    function isClickable($label) {
        return $this->isSubmit($label) || ($this->getLink($label) !== false) || $this->isImage($label);
    }
}
?>