LibWeb: Add actual document loading for the CSS (at)import rule

Author: https://github.com/speles
Commit: https://github.com/SerenityOS/serenity/commit/183ebaee91a
Pull-request: https://github.com/SerenityOS/serenity/pull/5456
Reviewed-by: https://github.com/awesomekling

AK/Debug.h.in

@@ -78,6 +78,10 @@
 #cmakedefine01 CSOCKET_DEBUG
 #endif
 
+#ifndef CSS_LOADER_DEBUG
+#cmakedefine01 CSS_LOADER_DEBUG
+#endif
+
 #ifndef CURSOR_TOOL_DEBUG
 #cmakedefine01 CURSOR_TOOL_DEBUG
 #endif

Meta/CMake/all_the_debug_macros.cmake

@@ -45,6 +45,7 @@ set(FILE_CONTENT_DEBUG ON)
 set(GZIP_DEBUG ON)
 set(CNETWORKJOB_DEBUG ON)
 set(CSOCKET_DEBUG ON)
+set(CSS_LOADER_DEBUG ON)
 set(SAFE_SYSCALL_DEBUG ON)
 set(GHASH_PROCESS_DEBUG ON)
 set(NT_DEBUG ON)

Userland/Libraries/LibWeb/CMakeLists.txt

@@ -176,6 +176,7 @@ set(SOURCES
     Layout/TreeBuilder.cpp
     LayoutTreeModel.cpp
     Loader/ContentFilter.cpp
+    Loader/CSSLoader.cpp
     Loader/FrameLoader.cpp
     Loader/ImageLoader.cpp
     Loader/ImageResource.cpp

Userland/Libraries/LibWeb/CSS/CSSImportRule.h

@@ -45,6 +45,11 @@ public:
 
     const URL& url() const { return m_url; }
 
+    bool has_import_result() const { return !m_style_sheet.is_null(); }
+    RefPtr<StyleSheet> loaded_style_sheet() { return m_style_sheet; }
+    const RefPtr<StyleSheet> loaded_style_sheet() const { return m_style_sheet; }
+    void set_style_sheet(const RefPtr<StyleSheet>& style_sheet) { m_style_sheet = style_sheet; }
+
     virtual StringView class_name() const { return "CSSImportRule"; };
     virtual Type type() const { return Type::Import; };
 
@@ -52,6 +57,7 @@ private:
     CSSImportRule(URL);
 
     URL m_url;
+    RefPtr<StyleSheet> m_style_sheet;
 };
 
 }

Userland/Libraries/LibWeb/CSS/StyleSheet.h

@@ -29,6 +29,7 @@
 
 #include <AK/NonnullRefPtrVector.h>
 #include <AK/TypeCasts.h>
+#include <LibWeb/CSS/CSSImportRule.h>
 #include <LibWeb/CSS/CSSRule.h>
 #include <LibWeb/Loader/Resource.h>
 
@@ -52,9 +53,32 @@ public:
         for (auto& rule : m_rules)
             if (rule.type() == CSSRule::Type::Style) {
                 callback(downcast<StyleRule>(rule));
+            } else if (rule.type() == CSSRule::Type::Import) {
+                const CSSImportRule& import_rule = downcast<CSSImportRule>(rule);
+                if (import_rule.has_import_result())
+                    import_rule.loaded_style_sheet()->for_each_effective_style_rule(callback);
             }
     }
 
+    template<typename Callback>
+    bool for_first_not_loaded_import_rule(Callback callback)
+    {
+        for (auto& rule : m_rules)
+            if (rule.type() == CSSRule::Type::Import) {
+                CSSImportRule& import_rule = downcast<CSSImportRule>(rule);
+                if (!import_rule.has_import_result()) {
+                    callback(import_rule);
+                    return true;
+                }
+
+                if (import_rule.loaded_style_sheet()->for_first_not_loaded_import_rule(callback)) {
+                    return true;
+                }
+            }
+
+        return false;
+    }
+
 private:
     explicit StyleSheet(NonnullRefPtrVector<CSSRule>&&);
 

Userland/Libraries/LibWeb/HTML/HTMLLinkElement.cpp

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, the SerenityOS developers.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -35,7 +36,11 @@ namespace Web::HTML {
 
 HTMLLinkElement::HTMLLinkElement(DOM::Document& document, QualifiedName qualified_name)
     : HTMLElement(document, move(qualified_name))
+    , m_css_loader(document)
 {
+    m_css_loader.on_load = [&] {
+        document.update_style();
+    };
 }
 
 HTMLLinkElement::~HTMLLinkElement()
@@ -46,44 +51,10 @@ void HTMLLinkElement::inserted_into(Node& node)
 {
     HTMLElement::inserted_into(node);
 
-    if (m_relationship & Relationship::Stylesheet && !(m_relationship & Relationship::Alternate))
-        load_stylesheet(document().complete_url(href()));
-}
-
-void HTMLLinkElement::resource_did_fail()
-{
-}
-
-void HTMLLinkElement::resource_did_load()
-{
-    VERIFY(resource());
-    if (!resource()->has_encoded_data())
-        return;
-
-    dbgln("HTMLLinkElement: Resource did load, looks good! {}", href());
-
-    auto sheet = parse_css(CSS::ParsingContext(document()), resource()->encoded_data());
-    if (!sheet) {
-        dbgln("HTMLLinkElement: Failed to parse stylesheet: {}", href());
-        return;
+    if (m_relationship & Relationship::Stylesheet && !(m_relationship & Relationship::Alternate)) {
+        m_css_loader.load_from_url(document().complete_url(href()));
+        document().style_sheets().add_sheet(m_css_loader.style_sheet().release_nonnull());
     }
-
-    // Transfer the rules from the successfully parsed sheet into the sheet we've already inserted.
-    m_style_sheet->rules() = sheet->rules();
-
-    document().update_style();
-}
-
-void HTMLLinkElement::load_stylesheet(const URL& url)
-{
-    // First insert an empty style sheet in the document sheet list.
-    // There's probably a nicer way to do this, but this ensures that sheets are in document order.
-    m_style_sheet = CSS::StyleSheet::create({});
-    document().style_sheets().add_sheet(*m_style_sheet);
-
-    LoadRequest request;
-    request.set_url(url);
-    set_resource(ResourceLoader::the().load_resource(Resource::Type::Generic, request));
 }
 
 void HTMLLinkElement::parse_attribute(const FlyString& name, const String& value)

Userland/Libraries/LibWeb/HTML/HTMLLinkElement.h

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, the SerenityOS developers.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -27,13 +28,11 @@
 #pragma once
 
 #include <LibWeb/HTML/HTMLElement.h>
-#include <LibWeb/Loader/Resource.h>
+#include <LibWeb/Loader/CSSLoader.h>
 
 namespace Web::HTML {
 
-class HTMLLinkElement final
-    : public HTMLElement
-    , public ResourceClient {
+class HTMLLinkElement final : public HTMLElement {
 public:
     using WrapperType = Bindings::HTMLLinkElementWrapper;
 
@@ -47,14 +46,8 @@ public:
     String href() const { return attribute(HTML::AttributeNames::href); }
 
 private:
-    // ^ResourceClient
-    virtual void resource_did_fail() override;
-    virtual void resource_did_load() override;
-
     void parse_attribute(const FlyString&, const String&) override;
 
-    void load_stylesheet(const URL&);
-
     struct Relationship {
         enum {
             Alternate = 1 << 0,
@@ -63,7 +56,7 @@ private:
     };
 
     unsigned m_relationship { 0 };
-    RefPtr<CSS::StyleSheet> m_style_sheet;
+    CSSLoader m_css_loader;
 };
 
 }

Userland/Libraries/LibWeb/HTML/HTMLStyleElement.cpp

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, the SerenityOS developers.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -25,7 +26,6 @@
  */
 
 #include <AK/StringBuilder.h>
-#include <LibWeb/CSS/Parser/CSSParser.h>
 #include <LibWeb/DOM/Document.h>
 #include <LibWeb/DOM/Text.h>
 #include <LibWeb/HTML/HTMLStyleElement.h>
@@ -34,7 +34,11 @@ namespace Web::HTML {
 
 HTMLStyleElement::HTMLStyleElement(DOM::Document& document, QualifiedName qualified_name)
     : HTMLElement(document, move(qualified_name))
+    , m_css_loader(document)
 {
+    m_css_loader.on_load = [&] {
+        document.update_style();
+    };
 }
 
 HTMLStyleElement::~HTMLStyleElement()
@@ -48,17 +52,15 @@ void HTMLStyleElement::children_changed()
         if (is<DOM::Text>(child))
             builder.append(downcast<DOM::Text>(child).text_content());
     });
-    m_stylesheet = parse_css(CSS::ParsingContext(document()), builder.to_string());
-    if (m_stylesheet)
-        document().style_sheets().add_sheet(*m_stylesheet);
-    else
-        document().style_sheets().add_sheet(CSS::StyleSheet::create({}));
+    m_css_loader.load_from_text(builder.to_string());
+    document().style_sheets().add_sheet(m_css_loader.style_sheet().release_nonnull());
+
     HTMLElement::children_changed();
 }
 
 void HTMLStyleElement::removed_from(Node& old_parent)
 {
-    if (m_stylesheet) {
+    if (m_css_loader.style_sheet()) {
         // FIXME: Remove the sheet from the document
     }
     return HTMLElement::removed_from(old_parent);

Userland/Libraries/LibWeb/HTML/HTMLStyleElement.h

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, the SerenityOS developers.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -27,6 +28,7 @@
 #pragma once
 
 #include <LibWeb/HTML/HTMLElement.h>
+#include <LibWeb/Loader/CSSLoader.h>
 
 namespace Web::HTML {
 
@@ -41,7 +43,7 @@ public:
     virtual void removed_from(Node&) override;
 
 private:
-    RefPtr<CSS::StyleSheet> m_stylesheet;
+    CSSLoader m_css_loader;
 };
 
 }

Userland/Libraries/LibWeb/Loader/CSSLoader.cpp

@@ -0,0 +1,111 @@
+/*
+ * Copyright (c) 2021, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/Debug.h>
+#include <AK/URL.h>
+#include <LibWeb/CSS/CSSImportRule.h>
+#include <LibWeb/CSS/Parser/CSSParser.h>
+#include <LibWeb/CSS/StyleSheet.h>
+#include <LibWeb/Loader/CSSLoader.h>
+#include <LibWeb/Loader/ResourceLoader.h>
+
+namespace Web {
+
+CSSLoader::CSSLoader(DOM::Document& document)
+    : m_document(&document)
+{
+}
+
+void CSSLoader::load_from_text(const String& text)
+{
+    m_style_sheet = parse_css(CSS::ParsingContext(*m_document), text);
+    if (!m_style_sheet)
+        m_style_sheet = CSS::StyleSheet::create({});
+
+    load_next_import_if_needed();
+}
+
+void CSSLoader::load_from_url(const URL& url)
+{
+    m_style_sheet = CSS::StyleSheet::create({});
+
+    LoadRequest request;
+    request.set_url(url);
+    set_resource(ResourceLoader::the().load_resource(Resource::Type::Generic, request));
+}
+
+void CSSLoader::resource_did_load()
+{
+    VERIFY(resource());
+
+    if (!resource()->has_encoded_data()) {
+        dbgln_if(CSS_LOADER_DEBUG, "CSSLoader: Resource did load, no encoded data. URL: {}", resource()->url());
+    } else {
+        dbgln_if(CSS_LOADER_DEBUG, "CSSLoader: Resource did load, has encoded data. URL: {}", resource()->url());
+    }
+
+    auto sheet = parse_css(CSS::ParsingContext(*m_document), resource()->encoded_data());
+    if (!sheet) {
+        dbgln_if(CSS_LOADER_DEBUG, "CSSLoader: Failed to parse stylesheet: {}", resource()->url());
+        return;
+    }
+
+    bool was_imported = m_style_sheet->for_first_not_loaded_import_rule([&](auto& rule) {
+        rule.set_style_sheet(sheet);
+    });
+
+    // Transfer the rules from the successfully parsed sheet into the sheet we've already inserted.
+    if (!was_imported) {
+        m_style_sheet->rules() = sheet->rules();
+    }
+
+    if (on_load)
+        on_load();
+
+    load_next_import_if_needed();
+}
+
+void CSSLoader::resource_did_fail()
+{
+    dbgln_if(CSS_LOADER_DEBUG, "CSSLoader: Resource did fail. URL: {}", resource()->url());
+
+    load_next_import_if_needed();
+}
+
+void CSSLoader::load_next_import_if_needed()
+{
+    // Create load request for the first import which isn't loaded.
+    // TODO: We need to somehow handle infinite cycles in imports.
+    m_style_sheet->for_first_not_loaded_import_rule([&](auto& rule) {
+        dbgln_if(CSS_LOADER_DEBUG, "CSSLoader: Loading @import {}", rule.url());
+
+        LoadRequest request;
+        request.set_url(rule.url());
+        set_resource(ResourceLoader::the().load_resource(Resource::Type::Generic, request));
+    });
+}
+
+}

Userland/Libraries/LibWeb/Loader/CSSLoader.h

@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/Function.h>
+#include <LibWeb/CSS/StyleSheet.h>
+#include <LibWeb/Loader/Resource.h>
+
+namespace Web {
+
+class CSSLoader : public ResourceClient {
+public:
+    CSSLoader(DOM::Document& document);
+
+    void load_from_text(const String&);
+    void load_from_url(const URL&);
+
+    void load_next_import_if_needed();
+
+    RefPtr<CSS::StyleSheet> style_sheet() const { return m_style_sheet; };
+
+    Function<void()> on_load;
+    Function<void()> on_fail;
+
+private:
+    // ^ResourceClient
+    virtual void resource_did_load() override;
+    virtual void resource_did_fail() override;
+
+    RefPtr<CSS::StyleSheet> m_style_sheet;
+    const DOM::Document* m_document;
+};
+
+}