Implement bracketed paste

Text pasted into Kakoune's normal mode is interpreted as command
sequence, which is probably never what the user wants. Text
pasted during insert mode will be inserted fine but may trigger
auto-indentation hooks which is likely not what users want.

Bracketed paste is pair of escape codes sent by terminals that allow
applications to distinguish between pasted text and typed text.

Let's use this feature to always insert pasted text verbatim, skipping
keymap lookup and the InsertChar hook. In future, we could add a
dedicated Paste hook.

We need to make a decision on whether to paste before or after the
selection. I chose "before" because that's what I'm used to.

TerminalUI::set_on_key has

	EventManager::instance().force_signal(0);

I'm not sure if we want the same for TerminalUI::set_on_paste?
I assume it doesn't matter because they are always called in tandem.

Closes #2465

1 files changed, 2 insertions, 0 deletions

diff --git a/src/user_interface.hh b/src/user_interface.hh
index 5bab3e89..643f0d1d 100644
--- a/src/user_interface.hh
+++ b/src/user_interface.hh
@@ -43,6 +43,7 @@ enum class CursorMode
 };
 
 using OnKeyCallback = std::function<void(Key key)>;
+using OnPasteCallback = std::function<void(StringView content)>;
 
 class UserInterface
 {
@@ -78,6 +79,7 @@ public:
     virtual void refresh(bool force) = 0;
 
     virtual void set_on_key(OnKeyCallback callback) = 0;
+    virtual void set_on_paste(OnPasteCallback callback) = 0;
 
     using Options = HashMap<String, String, MemoryDomain::Options>;
     virtual void set_ui_options(const Options& options) = 0;