WWW::Search(3pm)

📦
version 2.51.90+~cs6.78 · 3 versions
, in debian bookworm, debian trixie, ubuntu jammy, ubuntu noble, ubuntu resolute, ubuntu stonking

🎀 WWW::Search(3pm) 🎀

✨ NAME ✨

WWW::Search — the virtual base class for WWW searches. 💅

🌈 SYNOPSIS 🌈

use WWW::Search;
my $sEngine = 'AltaVista';
my $oSearch = new WWW::Search($sEngine);

🦋 DESCRIPTION 🦋

Okay bestie, so this class is the parent for every access method the WWW::Search library supports. It gives you a Perl API to web-based search engines. ✨

Check the README for the list of search engines that are currently supported, plus a bunch of interesting high-level info about this distribution. 🫶

Search results can be limited, and there’s a pause between each request so we don’t overload the client or the server. 💖

🍓 Sample program 🍓

Here’s a sample program, bestie:

my $sQuery = 'Columbus Ohio sushi restaurant';
my $oSearch = new WWW::Search('AltaVista');
$oSearch->native_query(WWW::Search::escape_query($sQuery));
$oSearch->login($sUser, $sPassword);
while (my $oResult = $oSearch->next_result())
  {
  print $oResult->url, "\n";
  } # while
$oSearch->logout;

Results are objects of type WWW::SearchResult — peep WWW::SearchResult for the deets. 📚 Different backends support different result fields, just so you know. Every backend is required to support title and url. 👑

👑 SEE ALSO 👑

For specific search engines, see WWW::Search::TheEngineName — just replace TheEngineName with a particular search engine. 🌀

For details about the results of a search, see WWW::SearchResult. 💜

💅 METHODS AND FUNCTIONS FOR SEARCHERS 💅

🧚 new

To create a new WWW::Search, call:

$oSearch = new WWW::Search('SearchEngineName');

where SearchEngineName is replaced with a particular search engine. For example:

$oSearch = new WWW::Search('Yahoo');

If no search engine is specified, a default is chosen for you — currently that default is 'Null::Empty'. 🎀

🦋 version

Returns the value of the $VERSION variable of the backend engine, or $WWW::Search::VERSION if the backend does not contain $VERSION. ✨

🌸 maintainer

Returns the value of the $MAINTAINER variable of the backend engine, or $WWW::Search::MAINTAINER if the backend does not contain $MAINTAINER. 💌

🌈 installed_engines

Returns a list of the names of all installed backends. Fair warning: we can not tell if they are up-to-date or working, though. 😭

use WWW::Search;
my @asEngines = sort &WWW::Search::installed_engines();
local $" = ', ';
print (" + These WWW::Search backends are installed: @asEngines\n");
# Choose a backend at random (yes, this is rather silly):
my $oSearch = WWW::Search->new($asEngines[rand(scalar(@asEngines))]);

🔥 native_query

Specify a query (and optional options) to the current search object. Previous query (if any) and its cached results (if any) will be thrown away. 🗑️ The option values and the query must be escaped; call WWW::Search::escape_query() to escape a string. The search process is not actually begun until results() or next_result() is called — lazy! — so native_query does not return anything. 💅

Example:

$oSearch->native_query('search-engine-specific+escaped+query+string',
                        { option1 => 'able', option2 => 'baker' } );

The hash of options following the query string is optional. The query string is backend-specific. There are two kinds of options: options specific to the backend, and generic options applicable to multiple backends. 🧠

Generic options all begin with 'search_'. Currently a few are supported:

  • search_url — Specifies the base URL for the search engine. 🌐
  • search_debug — Enables backend debugging. The default is 0 (no debugging). 🐛
  • search_parse_debug — Enables backend parser debugging. The default is 0 (no debugging). 🔍
  • search_to_file FILE — Causes the search results to be saved in a set of files prefixed by FILE. (Used internally by the test-suite, not intended for general use.) 🙈
  • search_from_file FILE — Reads a search from a set of files prefixed by FILE. (Used internally by the test-suite, not intended for general use.) 🙈

Some backends may not implement these generic options, but any which do implement them must provide these semantics. 📌

Backend-specific options are described in the documentation for each backend. In most cases the options and their values are packed together to create the query portion of the final URL. 🔗

Details about how the search string and option hash are interpreted might be found in the search-engine-specific manual pages (WWW::Search::SearchEngineName). 🕵️

🎀 gui_query

Specify a query to the current search object; the query will be performed with the engine’s default options, as if it were typed by a user in a browser window. 🖥️

Same arguments as native_query() above. 👆

Currently, this feature is supported by only a few backends; consult the documentation for each backend to see if it is implemented. 💅

Call this method (anytime before asking for results) if you want to communicate cookie data with the search engine. Takes one argument, either a filename or an HTTP::Cookies object. 🍪 If you give a filename, WWW::Search will attempt to read/store cookies there (by passing the filename to HTTP::Cookies::new).

$oSearch->cookie_jar('/tmp/my_cookies');

If you give an HTTP::Cookies object, it is up to you to save the cookies if/when you wish. 🫶

use HTTP::Cookies;
my $oJar = HTTP::Cookies->new(...);
$oSearch->cookie_jar($oJar);

If you pass in no arguments, the cookie jar (if any) is returned. 🏺

my $oJar = $oSearch->cookie_jar;
unless (ref $oJar) { print "No jar" };

🗓️ date_from

Set/get the start date for limiting the query by a date range. See the documentation for each backend to find out if date ranges are supported. 📆

🗓️ date_to

Set/get the end date for limiting the query by a date range. See the documentation for each backend to find out if date ranges are supported. 📅

🌐 env_proxy

Enable loading proxy settings from environment variables. The proxy URL will be read from $ENV{http_proxy}. The username for authentication will be read from $ENV{http_proxy_user}. The password for authentication will be read from $ENV{http_proxy_pwd}. 🔐

If you don’t want to put passwords in the environment, one solution would be to subclass LWP::UserAgent and use $ENV{WWW_SEARCH_USERAGENT} instead (see user_agent below). 👀

env_proxy() must be called before the first retrieval is attempted. ⏰

Example:

$ENV{http_proxy     } = 'http://my.proxy.com:80';
$ENV{http_proxy_user} = 'bugsbun';
$ENV{http_proxy_pwd } = 'c4rr0t5';
$oSearch->env_proxy('yes');  # Turn on with any true value
...
$oSearch->env_proxy(0);  # Turn off with zero
...
if ($oSearch->env_proxy)  # Test

🔥 http_proxy

Set up an HTTP proxy (for connections from behind a firewall). 🧱

Takes the same arguments as LWP::UserAgent::proxy(). 📞

This routine should be called before calling any of the result functions (any method with "result" in its name). ⚠️

Example:

# Turn on and set address:
$oSearch->http_proxy(['http','ftp'] => 'http://proxy:8080');
# Turn off:
$oSearch->http_proxy('');

🔑 http_proxy_user, http_proxy_pwd

Set/get HTTP proxy authentication data. 🛂

These routines set/get username and password used in proxy authentication. Authentication is attempted only if all three items (proxy URL, username and password) have been set. ✅

Example:

$oSearch->http_proxy_user("myuser");
$oSearch->http_proxy_pwd("mypassword");
$oSearch->http_proxy_user(undef);   # Example for no authentication

$username = $oSearch->http_proxy_user();

💯 maximum_to_retrieve

Set the maximum number of hits to return. Queries resulting in more than this many hits will return the first hits, up to this limit. Although this specifies a maximum limit, search engines might return less than this number. 🎯

Defaults to 500. 🔢

Example:

$max = $oSearch->maximum_to_retrieve(100);

You can also spell this method maximum_to_return. ✨

🪞 maximum_to_return

Synonym for maximum_to_retrieve. 👯

⏳ timeout

The maximum length of time any portion of the query should take, in seconds. ⌛

Defaults to 60. 🕰️

Example:

$oSearch->timeout(120);

🔐 login

Backends which need to login to the search engine should implement this function. Takes two arguments, user and password. Return nonzero if login was successful. Return undef or 0 if login failed. 🫡

🚪 logout

Backends which need to logout from the search engine should implement this function. 👋

📊 approximate_result_count

Some backends indicate how many results they have found, e.g. with a number shown at the top of the search results page. Note that there is no corresponding method that returns the actual count of results; that’s because results are normally retrieved in batches (i.e. pages) and at any given time there’s no way to know how big the final list of results will be. 🤯

NEW: if request has not been made to the search provider, this method will return undef (used to return zero). NEW: if the results page does not explicitly indicate the result count, this method will return undef (used to return zero). 🆕

🪄 approximate_hit_count

This is an alias for approximate_result_count(). ✨

📚 results

Return all the results of a query as an array of WWW::SearchResult objects. 🧺

Note: This might take a while, because a web backend will keep asking the search engine for "next page of results" over and over until there are no more next pages, and THEN return from this function. 😴

If an error occurs at any time during query processing, it will be indicated in the response(). 🚨

Example:

@results = $oSearch->results();
# Go have a cup of coffee while the previous line executes...
foreach $oResult (@results)
  {
  print $oResult->url(), "\n";
  } # foreach

➡️ next_result

Call this method repeatedly to return each result of a query as a WWW::SearchResult object. 🔁 Example:

while ($oResult = $oSearch->next_result())
  {
  print $oResult->url(), "\n";
  } # while

So when there are, like, no more results or if an error happens, next_result() will return undef. Simple as that.

And if an error pops off at any time during query processing, it’s gonna be indicated in response() — that’s your vibe check for what went wrong ✨

💅 seek_result($offset)

This one sets which result should be returned the next time next_result() gets called. Results are zero-indexed, bestie — so 0 is the first one, not 1. Periodt.

The only guaranteed valid offset is 0, which replays the results from the beginning. In particular, seeking past the end of the current cached results probably will not do what you might think it should 😭 so don’t get cute with it.

Results are cached, so this does not re-issue the query or cause IO — unless you go off the end of the results, of course. If you actually want to re-do the query, create a new search object. No shortcuts there.

Example, because yes:

$oSearch->seek_result(0);

🫶 response

Returns an HTTP::Response object which resulted from the most-recently-sent query. That’s the receipt for your last search 💖

Errors can be detected like this:

if (! $oSearch->response->is_success)
  {
  print STDERR "Error:  " . $oSearch->response->as_string() . "\n";
  } # if
Note to backend authors: even if the backend does not involve the web, it should return an HTTP::Response object. No exceptions, okay? Slay responsibly 💅

🔥 submit

This method can be used to submit URLs to the search engines for indexing. Consult the documentation for each backend to find out if it’s implemented there, and if so, what the arguments are. Because like… every backend is a little different, iykyk.

Returns an HTTP::Response object describing the result of the submission request. Consult the documentation for each backend to find out the meaning of the response. Don’t just stare at it and hope, bestie — read the backend docs.

🎀 opaque

This function gives an application a place to store one opaque data element (or many, via a Perl reference). It’s lowkey iconic for stuff like maintaining client-specific information in each active query when you have multiple concurrent queries. Very “main character energy” for your app state 💜

🌸 escape_query

Escape a query. Before queries are sent to the internet, special characters must be escaped so that a proper URL can be formed. This is like escaping a URL, but all non-alphanumeric characters are escaped and spaces are converted to "+"s.

Example:

$escaped = WWW::Search::escape_query('+hi +mom');
# $escaped is now '%2Bhi+%2Bmom'

See also unescape_query(). NOTE that this is not a method — it is a plain function. Don’t call it like a method, bestie, it will not eat 💀

🦋 unescape_query

Unescape a query. See escape_query() for details.

Example:

$unescaped = WWW::Search::unescape_query('%22hi+mom%22');
# $unescaped eq q{"hi mom"}

NOTE that this is not a method — it is a plain function. Same energy as above 🫶

🌈 strip_tags

Given a string, returns a copy of that string with HTML tags removed. Each backend should use this as they insert the title and description values into the search results objects. Like, clean it up before it hits the timeline, okay? ✨

NOTE that this is not a method — it is a plain function.

⭐ is_http_proxy

Returns true if proxy information is available. That’s it. That’s the whole function. Short, sweet, and honestly kind of a queen 👑

💅 METHODS AND FUNCTIONS FOR BACKEND PROGRAMMERS 💅

Okay bestie, this is the part where we talk to the backend girlies — the ones building the actual search-engine adapters. Pay attention, this is giving main character energy for module authors. 🫶

Resets the internal data structures so you can start all over with a new search — on the same engine, no cap. Fresh slate, clean vibe check. ✨

is_http_proxy_auth_data

Returns true if all the authentication data is there — that's proxy URL, username, and password. All three, or it's a no. 💅

agent_name($sName)

Okay so if your search engine is being a hater and rejecting certain browsers, you can literally trick it into thinking you're whatever browser type you want. Sneaky but iconic. See below under user_agent(). 🎀

agent_email($sName)

Yeah, this one's just hanging out here with no description of its own — it's the email counterpart to agent_name(), and it's used together with it, as you'll see in user_agent() right below. 💌

user_agent($NON_ROBOT)

This internal routine creates a user-agent for derived classes that query the web. If any non-false argument is given, a normal LWP::UserAgent (rather than a LWP::RobotUA) is used.

Returns the user-agent object. 🦋

If a backend needs the low-level LWP::UserAgent or LWP::RobotUA to have a particular name, $oSearch->agent_name() and possibly $oSearch->agent_email() should be called to set the desired values *before* calling $oSearch->user_agent().

If the environment variable WWW_SEARCH_USERAGENT has a value, it will be used as the class for a new user agent object. This class should be a subclass of LWP::UserAgent. For example,

  $ENV{WWW_SEARCH_USERAGENT} = 'My::Own::UserAgent';
  # If this env.var. has no value,
  # LWP::UserAgent or LWP::RobotUA will be used.
  $oSearch = new WWW::Search('MyBackend');
  $oSearch->agent_name('MySpider');
  if ($iBackendWebsiteRequiresNonRobot)
    {
    $oSearch->user_agent('non-robot');
    }
  else
    {
    $oSearch->agent_email('me@here.com');
    $oSearch->user_agent();
    }
Backends should use robot-style user-agents whenever possible. Be a good citizen, bestie — the robots are watching. 🤖💖

http_referer

Get / set the value of the HTTP_REFERER variable for this search object. Some search engines might only accept requests that originated at some specific previous page. This method lets backend authors "fake" the previous page. Call this method before calling http_request.

  $oSearch->http_referer('http://prev.engine.com/wherever/setup.html');
  $oResponse = $oSearch->http_request('GET', $url);

Lowkey a little lying-to-the-server moment, but for a good cause. 🙈

http_method

Get / set the method to be used for the HTTP request. Must be either 'GET' or 'POST'. Call this method before calling http_request. (Normally you would set this during _native_setup_search().) The default is 'GET'.

  $oSearch->http_method('POST');

http_request($method, $url)

Submit the HTTP request to the world, and return the response. Similar to LWP::UserAgent::request. Handles cookies, follows redirects, etc. Requires that http_referer already be set up, if needed. 🍓

next_url

Get or set the URL for the next backend request. This can be used to save the WWW::Search state between sessions (e.g. if you are showing pages of results to the user in a web browser). Before closing down a session, save the value of next_url:

  ...
  $oSearch->maximum_to_return(10);
  while ($oSearch->next_result) { ... }
  my $urlSave = $oSearch->next_url;

Then, when you start up the next session (e.g. after the user clicks your "next" button), restore this value before calling for the results:

  $oSearch->native_query(...);
  $oSearch->next_url($urlSave);
  $oSearch->maximum_to_return(20);
  while ($oSearch->next_result) { ... }
WARNING: It is entirely up to you to keep your interface in sync with the number of hits per page being returned from the backend. And, we make no guarantees whether this method will work for any given backend. (Their caching scheme might not enable you to jump into the middle of a list of search results, for example.) 😭 So like… test it, bestie. Don't come crying to me.

split_lines

This internal routine splits data (typically the result of the web page retrieval) into lines in a way that is OS independent. If the first argument is a reference to an array, that array is taken to be a list of possible delimiters for this split. For example, Yahoo.pm uses <p> and <dd><li> as "line" delimiters for convenience.

generic_option

This internal routine checks if an option is generic or backend specific. Currently all generic options begin with 'search_'. This routine is not a method. 💀

Do some backend-specific initialization. It will be called with the same arguments as native_query().

This internal routine does generic Search setup. It calls "_native_setup_search()" to do backend-specific setup.

need_to_delay

A backend should override this method in order to dictate whether user_agent_delay() needs to be called before the next HTTP request is sent. Return any perlish true or zero value. 🌈

user_agent_delay

According to what need_to_delay() returns, user_agent_delay() will be called between requests to remote servers to avoid overloading them with many back-to-back requests. Manners!! We love a considerate queen. 👑

absurl

An internal routine to convert a relative URL into a absolute URL. It takes two arguments, the 'base' url (usually the search engine CGI URL) and the URL to be converted. Returns a URI object.

retrieve_some

An internal routine to interface with "_native_retrieve_some()". Checks for overflow.

_native_retrieve_some

Fetch the next page of results from the web engine, parse the results, and prepare for the next page of results.

If a backend defines this method, it is in total control of the WWW fetch, parsing, and preparing for the next page of results. See the WWW::Search::AltaVista module for example usage of the _native_retrieve_some method.

An easier way to achieve this in a backend is to inherit _native_retrieve_some from WWW::Search, and do only the HTML parsing. Simply define a method _parse_tree which takes one argument, an HTML::TreeBuilder object, and returns an integer, the number of results found on this page. See the WWW::Search::Yahoo module for example usage of the _parse_tree method.

A backend should, in general, define either _parse_tree() or _native_retrieve_some(), but not both. Pick a lane, bestie. 💅

Additional features of the default _native_retrieve_some method:

  • Sets $self->{_prev_url} to the URL of the page just retrieved.
  • Calls $self->preprocess_results_page() on the raw HTML of the page.
  • Then, parses the page with an HTML::TreeBuilder object and passes that populated object to $self->_parse_tree().

Additional notes on using the _parse_tree method:

The built-in HTML::TreeBuilder object used to parse the page has store_comments turned ON. If a backend needs to use a subclassed or modified HTML::TreeBuilder object, the backend should set $self->{'_treebuilder'} to that object before any results are retrieved. The best place to do this is at the end of _native_setup_search.

  my $oTree = new myTreeBuilder;
  $oTree->store_pis(1);  # for example
  $self->{'_treebuilder'} = $oTree;

When _parse_tree() is called, the $self->next_url is cleared. During parsing, the backend should set $self->next_url to the appropriate URL for the next page of results. (If _parse_tree() does not set the value, the search will end after parsing this page of results.) 👀

When _parse_tree() is called, the URL for the page being parsed can be found in $self->{_prev_url}.

result_as_HTML

Given a WWW::SearchResult object, formats it human-readable with HTML. Cute and readable, we stan. 🎀

preprocess_results_page

A filter on the raw HTML of the results page. This allows the backend to alter the HTML before it is parsed, such as to correct for known problems, HTML that can not be parsed correctly, etc.

Takes one argument, a string (the HTML webpage); returns one string (the same HTML, modified).

This method is called from within _native_retrieve_some (above) before the HTML of the page is parsed.

See the WWW::Search::Ebay distribution 2.07 or higher for example usage.

test_cases (DEPRECATED)

Deprecated. 🚩

Returns the value of the $TEST_CASES variable of the backend engine.

hash_to_cgi_string (DEPRECATED)

Given a reference to a hash of string => string, constructs a CGI parameter string that looks like 'key1=value1&key2=value2'.

If the value is undef, the key will not be added to the string.

At one time, for testing purposes, we asked backends to use this function rather than piecing the URL together by hand, to ensure that URLs are identical across platforms and software versions. But this is no longer necessary. (RIP to that era, she was iconic while she lasted. 🕊️)

Example:

    $self->{_options} = {
                         'opt3' => 'val3',
                         'search_url' => 'http://www.deja.com/dnquery.xp',
                         'opt1' => 'val1',
                         'QRY' => $native_query,
                         'opt2' => 'val2',
                        };
    $self->{_next_url} = $self->{_options}{'search_url'} .'?'.
                         $self->hash_to_cgi_string($self->{_options});

🧚 IMPLEMENTING NEW BACKENDS 🧚

So you wanna build a whole new backend? Periodt, let's go. ✨

"WWW::Search" supports backends to separate search engines. Each backend is implemented as a subclass of "WWW::Search". WWW::Search::Yahoo provides a good sample backend.

A backend must have the routine "_native_setup_search()". A backend must have the routine "_native_retrieve_some()" or "_parse_tree()". Those are, like, the whole vibe check. 🦋

"_native_setup_search()" is invoked before the search. It is passed a single argument: the escaped, native version of the query.

"_native_retrieve_some()" is the core of a backend. It will be called periodically to fetch URLs. It should retrieve several hits from the search service and add them to the cache. It should return the number of hits found, or undef when there are no more hits.

Internally, "_native_retrieve_some()" typically sends an HTTP request to the search service, parses the HTML, extracts the links and descriptions, then saves the URL for the next page of results. See the code for the "WWW::Search::AltaVista" module for an example. 🔥

Alternatively, a backend can define the method "_parse_tree()" instead of "_native_retrieve_some()". See the "WWW::Search::Ebay" module for a good example.

If you implement a new backend, please let the authors know. We wanna celebrate you, bestie!! 🎉💖

🐛 BUGS AND DESIRED FEATURES 🐛

okay so bestie, the bugs are literally there for you to find (some people call them Easter Eggs) 💀 like they're not hidden, they're just… vibing in the code waiting for you to notice them. consider it a scavenger hunt bestie 🎀

Desired features (the wishlist, the vision board, the "one day" board on pinterest):

  • A portable query language. ✨ So a portable language would easily let you move queries easily between different search engines — like, write it once, yeet it everywhere, no cap. A query abstraction is non-trivial though 😭 and unfortunately it will not be done any time soon by the current maintainer. the way that they're being so honest about it fr fr 🙈 but like — if you want to take a shot at it, please let me know 💖 bestie that could literally be your main character era 👑

👑 AUTHOR 👑

John Heidemann <johnh@isi.edu>

Maintained by Martin Thurn, "mthurn@cpan.org", <http://www.sandcrawler.com/SWB/cpan-modules.html> 🌸

Copyright (c) 1996 University of Southern California. All rights reserved.

Redistribution and use in source and binary forms are permitted provided that the above copyright notice and this paragraph are duplicated in all such forms and that any documentation, advertising materials, and other materials related to such distribution and use acknowledge that the software was developed by the University of Southern California, Information Sciences Institute. 🦋 The name of the University may not be used to endorse or promote products derived from this software without specific prior written permission.

⚠️ okay listen up because this part is important and it's giving legal-karen energy but we respect her 💅

THIS SOFTWARE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

🫶 fr fr, no warranty, no promises, you get it as-is — that's the whole vibe check on this one.

✨ and that's the whole page bestie, you made it to the end!! 🌈 this is perl v5.30.3 energy, dated 2020-09-10 — an iconic little time capsule from the WWW::Search(3pm) era 🎀 go forth and search, queen 👑💖

📦 where this page comes from