vim-patch:8.2.1588: cannot read back the prompt of a prompt buffer

Problem:    Cannot read back the prompt of a prompt buffer.
Solution:   Add prompt_getprompt(). (Ben Jackson, closes vim/vim#6851)
https://github.com/vim/vim/commit/077cc7aa0e0c431e97795612374fe17fe7c88803

Updated prompt_getprompt() doc to https://github.com/vim/vim/commit/cb80aa2d53e56d3aba3b3c439fb467f29a750c5e
and removed mention of method syntax usage (not supported by Nvim).

1 files changed, 20 insertions, 0 deletions

diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index 206f76ba8e..6d328953f6 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -6491,6 +6491,26 @@ static void f_prompt_setinterrupt(typval_T *argvars,
     buf->b_prompt_interrupt= interrupt_callback;
 }
 
+/// "prompt_getprompt({buffer})" function
+void f_prompt_getprompt(typval_T *argvars, typval_T *rettv, FunPtr fptr)
+  FUNC_ATTR_NONNULL_ALL
+{
+  // return an empty string by default, e.g. it's not a prompt buffer
+  rettv->v_type = VAR_STRING;
+  rettv->vval.v_string = NULL;
+
+  buf_T *const buf = tv_get_buf_from_arg(&argvars[0]);
+  if (buf == NULL) {
+    return;
+  }
+
+  if (!bt_prompt(buf)) {
+    return;
+  }
+
+  rettv->vval.v_string = vim_strsave(buf_prompt_text(buf));
+}
+
 // "prompt_setprompt({buffer}, {text})" function
 static void f_prompt_setprompt(typval_T *argvars,
                                typval_T *rettv, FunPtr fptr)