ext_cmdline: add support for highlighting

src/nvim/api/private/helpers.c

@@ -703,6 +703,23 @@ String cstr_to_string(const char *str)
     };
 }
 
+/// Copies buffer to an allocated String.
+/// The resulting string is also NUL-terminated, to facilitate interoperating
+/// with code using C strings.
+///
+/// @param buf the buffer to copy
+/// @param size length of the buffer
+/// @return the resulting String, if the input string was NULL, an
+///         empty String is returned
+String cbuf_to_string(const char *buf, size_t size)
+  FUNC_ATTR_NONNULL_ALL
+{
+  return (String) {
+    .data = xmemdupz(buf, size),
+    .size = size
+  };
+}
+
 /// Creates a String using the given C string. Unlike
 /// cstr_to_string this function DOES NOT copy the C string.
 ///

src/nvim/ex_getln.c

@@ -2372,6 +2372,7 @@ static bool color_cmdline(const CmdlineInfo *const colored_ccline,
   FUNC_ATTR_NONNULL_ALL FUNC_ATTR_WARN_UNUSED_RESULT
 {
   bool printed_errmsg = false;
+
 #define PRINT_ERRMSG(...) \
   do { \
     msg_putchar('\n'); \
@@ -2405,7 +2406,7 @@ static bool color_cmdline(const CmdlineInfo *const colored_ccline,
 
   static unsigned prev_prompt_id = UINT_MAX;
   static int prev_prompt_errors = 0;
-  Callback color_cb = { .type = kCallbackNone };
+  Callback color_cb = CALLBACK_NONE;
   bool can_free_cb = false;
   TryState tstate;
   Error err = ERROR_INIT;
@@ -2722,10 +2723,30 @@ draw_cmdline_no_arabicshape:
 void ui_ext_cmdline_show(void)
 {
   Array content = ARRAY_DICT_INIT;
-  Array text = ARRAY_DICT_INIT;
-  ADD(text, STRING_OBJ(cstr_to_string("Normal")));
-  ADD(text, STRING_OBJ(cstr_to_string((char *)(ccline.cmdbuff))));
-  ADD(content, ARRAY_OBJ(text));
+  if (kv_size(last_ccline_colors.colors)) {
+    for (size_t i = 0; i < kv_size(last_ccline_colors.colors); i++) {
+      CmdlineColorChunk chunk = kv_A(last_ccline_colors.colors, i);
+      Array item = ARRAY_DICT_INIT;
+
+      if (chunk.attr) {
+        attrentry_T *aep = syn_cterm_attr2entry(chunk.attr);
+        // TODO(bfredl): this desicion could be delayed by making attr_code a
+        // recognized type
+        HlAttrs rgb_attrs = attrentry2hlattrs(aep, true);
+        ADD(item, DICTIONARY_OBJ(hlattrs2dict(rgb_attrs)));
+      } else {
+        ADD(item, DICTIONARY_OBJ((Dictionary)ARRAY_DICT_INIT));
+      }
+      ADD(item, STRING_OBJ(cbuf_to_string((char *)ccline.cmdbuff + chunk.start,
+                                          chunk.end-chunk.start)));
+      ADD(content, ARRAY_OBJ(item));
+    }
+  } else {
+    Array item = ARRAY_DICT_INIT;
+    ADD(item, DICTIONARY_OBJ((Dictionary)ARRAY_DICT_INIT));
+    ADD(item, STRING_OBJ(cstr_to_string((char *)(ccline.cmdbuff))));
+    ADD(content, ARRAY_OBJ(item));
+  }
   ui_call_cmdline_show(content, ccline.cmdpos,
                        cchar_to_string((char)ccline.cmdfirstc),
                        cstr_to_string((char *)(ccline.cmdprompt)),