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
 {

src/nvim/buffer_defs.h

@@ -438,6 +438,9 @@ typedef TV_DICTITEM_STRUCT(sizeof("changedtick")) ChangedtickDictItem;
 #define BUF_HAS_QF_ENTRY 1
 #define BUF_HAS_LL_ENTRY 2
 
+// Maximum number of maphash blocks we will have
+#define MAX_MAPHASH 256
+
 /*
  * buffer: structure that holds information about one file
  *
@@ -526,8 +529,8 @@ struct file_buffer {
    */
   uint64_t b_chartab[4];
 
-  /* Table used for mappings local to a buffer. */
-  mapblock_T  *(b_maphash[256]);
+  // Table used for mappings local to a buffer.
+  mapblock_T  *(b_maphash[MAX_MAPHASH]);
 
   /* First abbreviation local to a buffer. */
   mapblock_T  *b_first_abbr;

src/nvim/eval.c

@@ -12102,22 +12102,7 @@ static void get_maparg(typval_T *argvars, typval_T *rettv, int exact)
     tv_dict_alloc_ret(rettv);
     if (rhs != NULL) {
       // Return a dictionary.
-      char_u *lhs = str2special_save(mp->m_keys, true);
-      char *const mapmode = map_mode_to_chars(mp->m_mode);
-      dict_T *dict = rettv->vval.v_dict;
-
-      tv_dict_add_str(dict, S_LEN("lhs"), (const char *)lhs);
-      tv_dict_add_str(dict, S_LEN("rhs"), (const char *)mp->m_orig_str);
-      tv_dict_add_nr(dict, S_LEN("noremap"), mp->m_noremap ? 1 : 0);
-      tv_dict_add_nr(dict, S_LEN("expr"),  mp->m_expr ? 1 : 0);
-      tv_dict_add_nr(dict, S_LEN("silent"), mp->m_silent ? 1 : 0);
-      tv_dict_add_nr(dict, S_LEN("sid"), (varnumber_T)mp->m_script_ID);
-      tv_dict_add_nr(dict, S_LEN("buffer"), (varnumber_T)buffer_local);
-      tv_dict_add_nr(dict, S_LEN("nowait"), mp->m_nowait ? 1 : 0);
-      tv_dict_add_str(dict, S_LEN("mode"), mapmode);
-
-      xfree(lhs);
-      xfree(mapmode);
+      mapblock_fill_dict(rettv->vval.v_dict, mp, buffer_local, true);
     }
   }
 }
@@ -12134,6 +12119,46 @@ static void f_luaeval(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   executor_eval_lua(cstr_as_string((char *)str), &argvars[1], rettv);
 }
 
+/// Fill a dictionary with all applicable maparg() like dictionaries
+///
+/// @param  dict  The dictionary to be filled
+/// @param  mp  The maphash that contains the mapping information
+/// @param  buffer_value  The "buffer" value
+/// @param  compatible  True for compatible with old maparg() dict
+void mapblock_fill_dict(dict_T *const dict,
+                        const mapblock_T *const mp,
+                        long buffer_value,
+                        bool compatible)
+    FUNC_ATTR_NONNULL_ALL
+{
+  char_u *lhs = str2special_save(mp->m_keys, true);
+  char *const mapmode = map_mode_to_chars(mp->m_mode);
+  varnumber_T noremap_value;
+
+  if (compatible) {
+    // Keep old compatible behavior
+    // This is unable to determine whether a mapping is a <script> mapping
+    noremap_value = !!mp->m_noremap;
+  } else {
+    // Distinguish between <script> mapping
+    // If it's not a <script> mapping, check if it's a noremap
+    noremap_value = mp->m_noremap == REMAP_SCRIPT ? 2 : !!mp->m_noremap;
+  }
+
+  tv_dict_add_str(dict, S_LEN("lhs"), (const char *)lhs);
+  tv_dict_add_str(dict, S_LEN("rhs"), (const char *)mp->m_orig_str);
+  tv_dict_add_nr(dict, S_LEN("noremap"), noremap_value);
+  tv_dict_add_nr(dict, S_LEN("expr"),  mp->m_expr ? 1 : 0);
+  tv_dict_add_nr(dict, S_LEN("silent"), mp->m_silent ? 1 : 0);
+  tv_dict_add_nr(dict, S_LEN("sid"), (varnumber_T)mp->m_script_ID);
+  tv_dict_add_nr(dict, S_LEN("buffer"), (varnumber_T)buffer_value);
+  tv_dict_add_nr(dict, S_LEN("nowait"), mp->m_nowait ? 1 : 0);
+  tv_dict_add_str(dict, S_LEN("mode"), mapmode);
+
+  xfree(lhs);
+  xfree(mapmode);
+}
+
 /*
  * "map()" function
  */

src/nvim/getchar.c

@@ -18,6 +18,7 @@
 #include "nvim/vim.h"
 #include "nvim/ascii.h"
 #include "nvim/getchar.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/charset.h"
 #include "nvim/cursor.h"
 #include "nvim/edit.h"
@@ -47,6 +48,7 @@
 #include "nvim/event/loop.h"
 #include "nvim/os/input.h"
 #include "nvim/os/os.h"
+#include "nvim/api/private/handle.h"
 
 /*
  * These buffers are used for storing:
@@ -102,11 +104,10 @@ static int block_redo = FALSE;
                        (NORMAL + VISUAL + SELECTMODE + \
                         OP_PENDING)) ? (c1) : ((c1) ^ 0x80))
 
-/*
- * Each mapping is put in one of the 256 hash lists, to speed up finding it.
- */
-static mapblock_T       *(maphash[256]);
-static int maphash_valid = FALSE;
+// Each mapping is put in one of the MAX_MAPHASH hash lists,
+// to speed up finding it.
+static mapblock_T *(maphash[MAX_MAPHASH]);
+static bool maphash_valid = false;
 
 /*
  * List used for abbreviations.
@@ -4237,3 +4238,17 @@ static bool typebuf_match_len(const uint8_t *str, int *mlen)
   *mlen = i;
   return str[i] == NUL;  // matched the whole string
 }
+
+/// Retrieve the mapblock at the index either globally or for a certain buffer
+///
+/// @param  index  The index in the maphash[]
+/// @param  buf  The buffer to get the maphash from. NULL for global
+mapblock_T *get_maphash(int index, buf_T *buf)
+    FUNC_ATTR_PURE
+{
+  if (index > MAX_MAPHASH) {
+    return NULL;
+  }
+
+  return (buf == NULL) ? maphash[index] : buf->b_maphash[index];
+}