LibManual: Allow directly obtaining any page's main section number

This has previously been incorrectly handled in a variety of
applications, e.g. subsections were not accounted for.

Userland/Libraries/LibManual/Node.h

@@ -26,6 +26,7 @@ public:
     virtual bool is_open() const { return false; }
     virtual ErrorOr<String> path() const = 0;
     virtual PageNode const* document() const = 0;
+    virtual unsigned section_number() const = 0;
 
     // Backend for the command-line argument format that Help and man accept. Handles:
     // [/path/to/documentation.md] (no second argument)

Userland/Libraries/LibManual/PageNode.cpp

@@ -27,6 +27,11 @@ ErrorOr<String> PageNode::path() const
     return TRY(String::formatted("{}/{}.md", TRY(m_section->path()), m_page));
 }
 
+unsigned PageNode::section_number() const
+{
+    return m_section->section_number();
+}
+
 ErrorOr<NonnullRefPtr<PageNode>> PageNode::help_index_page()
 {
     static NonnullRefPtr<PageNode> const help_index_page = TRY(try_make_ref_counted<PageNode>(sections[7 - 1], TRY("Help-index"_string)));

Userland/Libraries/LibManual/PageNode.h

@@ -28,6 +28,7 @@ public:
     virtual ErrorOr<String> name() const override { return m_page; };
     virtual bool is_page() const override { return true; }
     virtual PageNode const* document() const override { return this; };
+    virtual unsigned section_number() const override;
 
     virtual ErrorOr<String> path() const override;
 

Userland/Libraries/LibManual/SectionNode.h

@@ -32,6 +32,7 @@ public:
     virtual Node const* parent() const override { return nullptr; }
     virtual ErrorOr<String> name() const override;
     String const& section_name() const { return m_section; }
+    virtual unsigned section_number() const override { return m_section.to_number<unsigned>().value_or(0); }
     virtual ErrorOr<String> path() const override;
     virtual PageNode const* document() const override { return nullptr; }
 

Userland/Libraries/LibManual/SubsectionNode.h

@@ -21,6 +21,7 @@ public:
     virtual ErrorOr<String> path() const override;
     virtual ErrorOr<String> name() const override;
     virtual PageNode const* document() const override;
+    virtual unsigned section_number() const override { return m_parent->section_number(); }
 
 protected:
     NonnullRefPtr<SectionNode const> m_parent;

Userland/Utilities/man.cpp

@@ -80,12 +80,12 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     auto page = TRY(Manual::Node::try_create_from_query(query_parameters));
     auto page_name = TRY(page->name());
-    auto const* section = static_cast<Manual::SectionNode const*>(page->parent());
+    auto section_number = TRY(String::number(page->section_number()));
 
     if (pager.is_empty())
         pager = TRY(String::formatted("less -P 'Manual Page {}({}) line %l?e (END):.'",
             TRY(page_name.replace("'"sv, "'\\''"sv, ReplaceMode::FirstOnly)),
-            TRY(section->section_name().replace("'"sv, "'\\''"sv, ReplaceMode::FirstOnly))));
+            section_number));
     pid_t pager_pid = TRY(pipe_to_pager(pager));
 
     auto file = TRY(Core::File::open(TRY(page->path()), Core::File::OpenMode::Read));
@@ -97,8 +97,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     auto const title = TRY("SerenityOS manual"_string);
 
-    int spaces = max(view_width / 2 - page_name.code_points().length() - section->section_name().code_points().length() - title.code_points().length() / 2 - 4, 0);
-    outln("{}({}){}{}", page_name, section->section_name(), String::repeated(' ', spaces), title);
+    int spaces = max(view_width / 2 - page_name.code_points().length() - section_number.code_points().length() - title.code_points().length() / 2 - 4, 0);
+    outln("{}({}){}{}", page_name, section_number, String::repeated(' ', spaces), title);
 
     auto document = Markdown::Document::parse(buffer);
     VERIFY(document);