Major updates/cleanup.

src/internal/functions/posix.cc

@@ -60,7 +60,21 @@ void Function::register_posix(BEd &ctx) {
       .desc = "Change a range of lines",
       .default_address = ".,.",
       .accept_zero = false,
-      .pre_text_mode = nullptr,
+      .pre_text_mode = [](
+                         BEd &ctx,
+                         const buffer::Address &addr_,
+                         const Argument &
+                       ) -> std::tuple<vase::Shard *, syntax::Language *, void *> {
+        const auto &addr = std::get<buffer::Range>(addr_);
+        auto &buf_ = ctx.buffer(addr.buffername);
+        if (buf_.kind != buffer::Buffer::Kind::Generic)
+          return {buf_.copy(addr.start, addr.end), nullptr, nullptr};
+        auto &buf = *(buffer::GenericBuffer *)&buf_;
+        if (!buf.parse.lang)
+          return {buf.copy(addr.start, addr.end), nullptr, nullptr};
+        void *state = nullptr; // TODO: buf.parse.root.get_at(addr.start);
+        return {buf.copy(addr.start, addr.end), buf.parse.lang, state};
+      },
       .handle = [](
                   BEd &ctx,
                   const buffer::Address &addr_,
@@ -68,10 +82,9 @@ void Function::register_posix(BEd &ctx) {
                   const Argument &,
                   std::vector<buffer::Line> *
                 ) {
-        auto addr = std::get<buffer::Range>(addr_);
+        const auto &addr = std::get<buffer::Range>(addr_);
         ctx.buffer(addr.buffername).replace(ctx, text, addr.start, addr.end);
-        vase::Shard::release(text);
-      }
+        vase::Shard::release(text); }
     }
   );
   ctx.functions.insert(