Add -override support to add-highlighter

This allow replacing a highlighter in place, not loosing its current
position in its parent.

Fixes #3436

doc/pages/commands.asciidoc

@@ -252,12 +252,12 @@ of the file onto the filesystem
 *colorscheme* <name>::
     load named colorscheme
 
-*add-highlighter* <highlighter_name> <highlighter_parameters> ...::
+*add-highlighter* [<switches>] <highlighter_path> <highlighter_parameters> ...::
     *alias* addhl +
     add a highlighter to the current window
     (See <<highlighters#,`:doc highlighters`>>)
 
-*remove-highlighter* <highlighter_id>::
+*remove-highlighter* <highlighter_path>::
     *alias* rmhl +
     remove the highlighter whose id is *highlighter_id*
     (See <<highlighters#,`:doc highlighters`>>)

doc/pages/highlighters.asciidoc

@@ -5,9 +5,9 @@
 Manipulation of the displayed text is done through highlighters, which can
 be added or removed with the following commands:
 
------------------------------------------------------
-add-highlighter <path>/<name> <type> <parameters> ...
------------------------------------------------------
+-----------------------------------------------------------------
+add-highlighter [-override] <path>/<name> <type> <parameters> ...
+-----------------------------------------------------------------
 
 and
 
@@ -23,6 +23,9 @@ separated path starting with a scope. Scopes are *global*, *buffer*,
 `add-highlighter` (the path ends with a `/`), it will be auto-generated
 from the remaining parameters.
 
+if `-override` is specified and the given name already exists, that
+highlighter is replaced with the new one.
+
 == Convenient highlighters
 
 *show-matching*::

src/commands.cc

@@ -950,7 +950,10 @@ const CommandDesc add_highlighter_cmd = {
     "add-highlighter <path>/<name> <type> <type params>...: add an highlighter to the group identified by <path>\n"
     "    <path> is a '/' delimited path or the parent highlighter, starting with either\n"
     "   'global', 'buffer', 'window' or 'shared', if <name> is empty, it will be autogenerated",
-    ParameterDesc{ {}, ParameterDesc::Flags::SwitchesAsPositional, 2 },
+    ParameterDesc{
+        { { "override", { false, "replace existing highlighter with same path if it exists" } }, },
+        ParameterDesc::Flags::SwitchesOnlyAtStart, 2
+    },
     CommandFlags::None,
     [](const Context& context, CommandParameters params) -> String
     {
@@ -990,7 +993,7 @@ const CommandDesc add_highlighter_cmd = {
         String name{slash.base(), path.end()};
         Highlighter& parent = get_highlighter(context, {path.begin(), slash.base() - 1});
         parent.add_child(name.empty() ? auto_name(parser.positionals_from(1)) : std::move(name),
-                            it->value.factory(highlighter_params, &parent));
+                         it->value.factory(highlighter_params, &parent), (bool)parser.get_switch("override"));
 
         redraw_relevant_clients(context, path);
     }

src/highlighter.cc

@@ -34,7 +34,7 @@ Highlighter& Highlighter::get_child(StringView path)
     throw runtime_error("this highlighter does not hold children");
 }
 
-void Highlighter::add_child(String name, std::unique_ptr<Highlighter>&& hl)
+void Highlighter::add_child(String, std::unique_ptr<Highlighter>&&, bool)
 {
     throw runtime_error("this highlighter does not hold children");
 }

src/highlighter.hh

@@ -69,7 +69,7 @@ struct Highlighter
 
     virtual bool has_children() const;
     virtual Highlighter& get_child(StringView path);
-    virtual void add_child(String name, std::unique_ptr<Highlighter>&& hl);
+    virtual void add_child(String name, std::unique_ptr<Highlighter>&& hl, bool override = false);
     virtual void remove_child(StringView id);
     virtual Completions complete_child(StringView path, ByteCount cursor_pos, bool group) const;
     virtual void fill_unique_ids(Vector<StringView>& unique_ids) const;

src/highlighter_group.cc

@@ -24,13 +24,19 @@ void HighlighterGroup::fill_unique_ids(Vector<StringView>& unique_ids) const
         hl.value->fill_unique_ids(unique_ids);
 }
 
-void HighlighterGroup::add_child(String name, std::unique_ptr<Highlighter>&& hl)
+void HighlighterGroup::add_child(String name, std::unique_ptr<Highlighter>&& hl, bool override)
 {
     if ((hl->passes() & passes()) != hl->passes())
         throw runtime_error{"cannot add that highlighter to this group, passes don't match"};
 
-    if (m_highlighters.contains(name))
+    auto it = m_highlighters.find(name);
+    if (it != m_highlighters.end())
+    {
+        if (not override)
             throw runtime_error(format("duplicate id: '{}'", name));
+        it->value = std::move(hl);
+        return;
+    }
 
     m_highlighters.insert({std::move(name), std::move(hl)});
 }

src/highlighter_group.hh

@@ -21,7 +21,7 @@ public:
     HighlighterGroup(HighlightPass passes) : Highlighter{passes} {}
 
     bool has_children() const override { return true; }
-    void add_child(String name, std::unique_ptr<Highlighter>&& hl) override;
+    void add_child(String name, std::unique_ptr<Highlighter>&& hl, bool override = false) override;
     void remove_child(StringView id) override;
 
     Highlighter& get_child(StringView path) override;

src/highlighters.cc

@@ -1873,11 +1873,12 @@ public:
             return it->value->get_child({sep_it+1, path.end()});
     }
 
-    void add_child(String name, std::unique_ptr<Highlighter>&& hl) override
+    void add_child(String name, std::unique_ptr<Highlighter>&& hl, bool override) override
     {
         if (not dynamic_cast<RegionHighlighter*>(hl.get()))
             throw runtime_error{"only region highlighter can be added as child of a regions highlighter"};
-        if (m_regions.contains(name))
+        auto it = m_regions.find(name);
+        if (not override and it != m_regions.end())
             throw runtime_error{format("duplicate id: '{}'", name)};
 
         std::unique_ptr<RegionHighlighter> region_hl{dynamic_cast<RegionHighlighter*>(hl.release())};
@@ -1888,6 +1889,9 @@ public:
             m_default_region = name;
         }
 
+        if (it != m_regions.end())
+            it->value = std::move(region_hl);
+        else
             m_regions.insert({std::move(name), std::move(region_hl)});
         ++m_regions_timestamp;
     }
@@ -2132,9 +2136,9 @@ private:
             return m_delegate->get_child(path);
         }
 
-        void add_child(String name, std::unique_ptr<Highlighter>&& hl) override
+        void add_child(String name, std::unique_ptr<Highlighter>&& hl, bool override) override
         {
-            return m_delegate->add_child(name, std::move(hl));
+            return m_delegate->add_child(name, std::move(hl), override);
         }
 
         void remove_child(StringView id) override