Add cancel buffer (to store cancelled operations.)

include/internal/buffer/types/generic.h

@@ -1,7 +1,7 @@
 #pragma once
 
 #include "../decl.h"
-#include "history.h"
+#include "readonly.h"
 #include "shard.h"
 
 namespace bed::internal::buffer {
@@ -25,7 +25,7 @@ struct GenericBuffer : ShardBuffer {
   ~GenericBuffer();
 
   void list_history(BEd &ctx);
-  HistoryBuffer *get_history(uint64_t version);
+  ReadonlyBuffer *get_history(uint64_t version);
   void snapshot(std::string action);
   bool undo(BEd &ctx);
   bool redo(BEd &ctx);

include/internal/buffer/types/readonly.h

@@ -4,36 +4,38 @@
 #include "shard.h"
 
 namespace bed::internal::buffer {
-struct HistoryBuffer : ShardBuffer {
-  HistoryBuffer(
+struct ReadonlyBuffer : ShardBuffer {
+  bool useless = true;
+
+  ReadonlyBuffer(
     std::string name, vase::Shard *root,
     const syntax::ParserSnapshot &snapshot
   ) : ShardBuffer(std::move(name), root, snapshot, Kind::History) {}
 
   bool waste() override {
-    return true;
+    return useless;
   }
   void load(BEd &, vase::Shard *) override {
-    throw ed_error("History buffers are read-only.");
+    throw ed_error("This buffer is read-only.");
   }
   void set_filename(std::filesystem::path) override {}
   std::filesystem::path filename() override {
     return {};
   }
   void substitute(BEd &, uint64_t, uint64_t, std::string &, std::string &, std::string &) override {
-    throw ed_error("History buffers are read-only.");
+    throw ed_error("This buffer is read-only.");
   }
   void join(BEd &, uint64_t, uint64_t) override {
-    throw ed_error("History buffers are read-only.");
+    throw ed_error("This buffer is read-only.");
   }
   void remove(BEd &, uint64_t, uint64_t) override {
-    throw ed_error("History buffers are read-only.");
+    throw ed_error("This buffer is read-only.");
   }
   void append(BEd &, vase::Shard *, uint64_t) override {
-    throw ed_error("History buffers are read-only.");
+    throw ed_error("This buffer is read-only.");
   }
   void replace(BEd &, vase::Shard *, uint64_t, uint64_t) override {
-    throw ed_error("History buffers are read-only.");
+    throw ed_error("This buffer is read-only.");
   }
 };
 } // namespace bed::internal::buffer