LibURL: Remove URL's valid state

No code now relies on using URL's valid state.

A URL can still be _technically_ invalid through use of the URL
constructor or by directly changing URL fields.

However, all URLs should be constructed through the URL parser,
and we should ideally be getting rid of the default constructor
at some stage.

Also, any code which is manually setting URL fields need to be
aware that this is full of pitfalls since there are many different
forms of canonicalization which is bypassed by not going through
the URL parser.

Libraries/LibURL/Parser.cpp

@@ -1663,7 +1663,6 @@ Optional<URL> Parser::basic_parse(StringView raw_input, Optional<URL const&> bas
         ++iterator;
     }
 
-    url->m_data->valid = true;
     dbgln_if(URL_PARSER_DEBUG, "URL::Parser::basic_parse: Parsed URL to be '{}'.", url->serialize());
 
     // 10. Return url.

Libraries/LibURL/URL.cpp

@@ -24,9 +24,6 @@ namespace URL {
 
 Optional<URL> URL::complete_url(StringView relative_url) const
 {
-    if (!is_valid())
-        return {};
-
     return Parser::basic_parse(relative_url, *this);
 }
 
@@ -38,8 +35,6 @@ ByteString URL::path_segment_at_index(size_t index) const
 
 ByteString URL::basename() const
 {
-    if (!m_data->valid)
-        return {};
     if (m_data->paths.is_empty())
         return {};
     auto& last_segment = m_data->paths.last();
@@ -49,7 +44,6 @@ ByteString URL::basename() const
 void URL::set_scheme(String scheme)
 {
     m_data->scheme = move(scheme);
-    m_data->valid = compute_validity();
 }
 
 // https://url.spec.whatwg.org/#set-the-username
@@ -57,7 +51,6 @@ void URL::set_username(StringView username)
 {
     // To set the username given a url and username, set url’s username to the result of running UTF-8 percent-encode on username using the userinfo percent-encode set.
     m_data->username = percent_encode(username, PercentEncodeSet::Userinfo);
-    m_data->valid = compute_validity();
 }
 
 // https://url.spec.whatwg.org/#set-the-password
@@ -65,13 +58,11 @@ void URL::set_password(StringView password)
 {
     // To set the password given a url and password, set url’s password to the result of running UTF-8 percent-encode on password using the userinfo percent-encode set.
     m_data->password = percent_encode(password, PercentEncodeSet::Userinfo);
-    m_data->valid = compute_validity();
 }
 
 void URL::set_host(Host host)
 {
     m_data->host = move(host);
-    m_data->valid = compute_validity();
 }
 
 // https://url.spec.whatwg.org/#concept-host-serializer
@@ -87,7 +78,6 @@ void URL::set_port(Optional<u16> port)
         return;
     }
     m_data->port = move(port);
-    m_data->valid = compute_validity();
 }
 
 void URL::set_paths(Vector<ByteString> const& paths)
@@ -96,7 +86,6 @@ void URL::set_paths(Vector<ByteString> const& paths)
     m_data->paths.ensure_capacity(paths.size());
     for (auto const& segment : paths)
         m_data->paths.unchecked_append(percent_encode(segment, PercentEncodeSet::Path));
-    m_data->valid = compute_validity();
 }
 
 void URL::append_path(StringView path)
@@ -112,33 +101,6 @@ bool URL::cannot_have_a_username_or_password_or_port() const
     return !m_data->host.has_value() || m_data->host->is_empty_host() || m_data->scheme == "file"sv;
 }
 
-// FIXME: This is by no means complete.
-// NOTE: This relies on some assumptions about how the spec-defined URL parser works that may turn out to be wrong.
-bool URL::compute_validity() const
-{
-    if (m_data->scheme.is_empty())
-        return false;
-
-    if (m_data->has_an_opaque_path) {
-        if (m_data->paths.size() != 1)
-            return false;
-        if (m_data->paths[0].is_empty())
-            return false;
-    } else {
-        if (m_data->scheme.is_one_of("about", "mailto"))
-            return false;
-        // NOTE: Maybe it is allowed to have a zero-segment path.
-        if (m_data->paths.size() == 0)
-            return false;
-    }
-
-    // FIXME: A file URL's host should be the empty string for localhost, not null.
-    if (m_data->scheme == "file" && !m_data->host.has_value())
-        return false;
-
-    return true;
-}
-
 // https://url.spec.whatwg.org/#default-port
 Optional<u16> default_port_for_scheme(StringView scheme)
 {
@@ -333,8 +295,6 @@ String URL::serialize(ExcludeFragment exclude_fragment) const
 //        resulting from percent-decoding those sequences converted to bytes, unless that renders those sequences invisible.
 ByteString URL::serialize_for_display() const
 {
-    VERIFY(m_data->valid);
-
     StringBuilder builder;
     builder.append(m_data->scheme);
     builder.append(':');
@@ -422,8 +382,6 @@ bool URL::equals(URL const& other, ExcludeFragment exclude_fragments) const
 {
     if (this == &other)
         return true;
-    if (!m_data->valid || !other.m_data->valid)
-        return false;
     return serialize(exclude_fragments) == other.serialize(exclude_fragments);
 }
 
@@ -495,7 +453,6 @@ String percent_encode(StringView input, PercentEncodeSet set, SpaceAsPlus space_
 URL URL::about(String path)
 {
     URL url;
-    url.m_data->valid = true;
     url.m_data->scheme = "about"_string;
     url.m_data->paths = { move(path) };
     url.m_data->has_an_opaque_path = true;

Libraries/LibURL/URL.h

@@ -77,10 +77,9 @@ class URL {
     friend class Parser;
 
 public:
+    // FIXME: We should get rid of the default constructor, all URLs should be constructed through the Parser.
     URL() = default;
 
-    bool is_valid() const { return m_data->valid; }
-
     String const& scheme() const { return m_data->scheme; }
     String const& username() const { return m_data->username; }
     String const& password() const { return m_data->password; }
@@ -147,13 +146,10 @@ public:
     static URL about(String path);
 
 private:
-    bool compute_validity() const;
-
     struct Data : public RefCounted<Data> {
-        NonnullRefPtr<Data> clone()
+        NonnullRefPtr<Data> clone() const
         {
             auto clone = adopt_ref(*new Data);
-            clone->valid = valid;
             clone->scheme = scheme;
             clone->username = username;
             clone->password = password;
@@ -167,8 +163,6 @@ private:
             return clone;
         }
 
-        bool valid { false };
-
         // A URL’s scheme is an ASCII string that identifies the type of URL and can be used to dispatch a URL for further processing after parsing. It is initially the empty string.
         String scheme;
 

Tests/LibURL/TestURL.cpp

@@ -10,11 +10,6 @@
 #include <LibURL/Parser.h>
 #include <LibURL/URL.h>
 
-TEST_CASE(construct)
-{
-    EXPECT_EQ(URL::URL().is_valid(), false);
-}
-
 TEST_CASE(basic)
 {
     {