buffer: Add WITH_BUFFER macro to simplify global buffer modification

Most internal functions to modify buffers operate on the current buffer and
require temporary switchs. This macro is a temporary workaround until a cleaner
refactoring of the internal API is performed.

1 files changed, 41 insertions, 0 deletions

diff --git a/src/nvim/buffer.h b/src/nvim/buffer.h
index a7f4feb342..49025d3925 100644
--- a/src/nvim/buffer.h
+++ b/src/nvim/buffer.h
@@ -1,6 +1,7 @@
 #ifndef NVIM_BUFFER_H
 #define NVIM_BUFFER_H
 
+#include "nvim/window.h"
 #include "nvim/pos.h"  // for linenr_T
 #include "nvim/ex_cmds_defs.h"  // for exarg_T
 
@@ -45,4 +46,44 @@ enum bfa_values {
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "buffer.h.generated.h"
 #endif
+
+// Find a window that contains "buf" and switch to it.
+// If there is no such window, use the current window and change "curbuf".
+// Caller must initialize save_curbuf to NULL.
+// restore_win_for_buf() MUST be called later!
+static inline void switch_to_win_for_buf(buf_T *buf,
+                                         win_T **save_curwinp,
+                                         tabpage_T **save_curtabp,
+                                         buf_T **save_curbufp)
+{
+  win_T *wp;
+  tabpage_T *tp;
+
+  if (!find_win_for_buf(buf, &wp, &tp)
+      || switch_win(save_curwinp, save_curtabp, wp, tp, true) == FAIL)
+    switch_buffer(save_curbufp, buf);
+}
+
+static inline void restore_win_for_buf(win_T *save_curwin,
+                                       tabpage_T *save_curtab,
+                                       buf_T *save_curbuf)
+{
+  if (save_curbuf == NULL) {
+    restore_win(save_curwin, save_curtab, true);
+  } else {
+    restore_buffer(save_curbuf);
+  }
+}
+
+#define WITH_BUFFER(b, code)                                              \
+  do {                                                                    \
+    buf_T *save_curbuf = NULL;                                            \
+    win_T *save_curwin = NULL;                                            \
+    tabpage_T *save_curtab = NULL;                                        \
+    switch_to_win_for_buf(b, &save_curwin, &save_curtab, &save_curbuf);   \
+    code;                                                                 \
+    restore_win_for_buf(save_curwin, save_curtab, save_curbuf);           \
+  } while (0)
+
+
 #endif  // NVIM_BUFFER_H