get_keymap API (#6236)

* Add api function get keymap

nvim_get_keymap(mode)
nvim_buf_get_keymap(buffer, mode)

src/nvim/api/buffer.c

@@ -453,6 +453,26 @@ Integer nvim_buf_get_changedtick(Buffer buffer, Error *err)
   return buf->b_changedtick;
 }
 
+/// Get a list of dictionaries describing buffer-local mappings
+/// Note that the buffer key in the dictionary will represent the buffer
+/// handle where the mapping is present
+///
+/// @param  mode  The abbreviation for the mode
+/// @param  buffer_id  Buffer handle
+/// @param[out]  err   Error details, if any
+/// @returns An array of maparg() like dictionaries describing mappings
+ArrayOf(Dictionary) nvim_buf_get_keymap(Buffer buffer, String mode, Error *err)
+    FUNC_API_SINCE(3)
+{
+  buf_T *buf = find_buffer_by_handle(buffer, err);
+
+  if (!buf) {
+    return (Array)ARRAY_DICT_INIT;
+  }
+
+  return keymap_array(mode, buf);
+}
+
 /// Sets a buffer-scoped (b:) variable
 ///
 /// @param buffer     Buffer handle

src/nvim/api/private/helpers.c

@@ -24,6 +24,7 @@
 #include "nvim/option_defs.h"
 #include "nvim/version.h"
 #include "nvim/lib/kvec.h"
+#include "nvim/getchar.h"
 
 /// Helper structure for vim_to_object
 typedef struct {
@@ -1034,3 +1035,41 @@ void api_set_error(Error *err, ErrorType errType, const char *format, ...)
 
   err->type = errType;
 }
+
+/// Get an array containing dictionaries describing mappings
+/// based on mode and buffer id
+///
+/// @param  mode  The abbreviation for the mode
+/// @param  buf  The buffer to get the mapping array. NULL for global
+/// @returns An array of maparg() like dictionaries describing mappings
+ArrayOf(Dictionary) keymap_array(String mode, buf_T *buf)
+{
+  Array mappings = ARRAY_DICT_INIT;
+  dict_T *const dict = tv_dict_alloc();
+
+  // Convert the string mode to the integer mode
+  // that is stored within each mapblock
+  char_u *p = (char_u *)mode.data;
+  int int_mode = get_map_mode(&p, 0);
+
+  // Determine the desired buffer value
+  long buffer_value = (buf == NULL) ? 0 : buf->handle;
+
+  for (int i = 0; i < MAX_MAPHASH; i++) {
+    for (const mapblock_T *current_maphash = get_maphash(i, buf);
+         current_maphash;
+         current_maphash = current_maphash->m_next) {
+      // Check for correct mode
+      if (int_mode & current_maphash->m_mode) {
+        mapblock_fill_dict(dict, current_maphash, buffer_value, false);
+        ADD(mappings, vim_to_object(
+            (typval_T[]) { { .v_type = VAR_DICT, .vval.v_dict = dict } }));
+
+        tv_dict_clear(dict);
+      }
+    }
+  }
+  tv_dict_free(dict);
+
+  return mappings;
+}

src/nvim/api/vim.c

@@ -742,6 +742,17 @@ Dictionary nvim_get_mode(void)
   return rv;
 }
 
+/// Get a list of dictionaries describing global (i.e. non-buffer) mappings
+/// Note that the "buffer" key will be 0 to represent false.
+///
+/// @param  mode  The abbreviation for the mode
+/// @returns  An array of maparg() like dictionaries describing mappings
+ArrayOf(Dictionary) nvim_get_keymap(String mode)
+    FUNC_API_SINCE(3)
+{
+  return keymap_array(mode, NULL);
+}
+
 Array nvim_get_api_info(uint64_t channel_id)
     FUNC_API_SINCE(1) FUNC_API_ASYNC FUNC_API_REMOTE_ONLY
 {