LSP: support ctags-lsp

* It sends `null` instead of empty lists, even though this is violating the LSP specs.
* Filter out duplicates from the auto-completion lists.
  This may benefit other servers as well.
* ctags-lsp does not fuzzy search for workspace/symbol, so auto-completions
  aren't really a thing.
  The only special case is sending the empty string, which results in
  all symbols being returned. This can be slow, though.
* ctags-lsp does not support textDocument/references, so n:FT$ won't be supported.

1 files changed, 16 insertions, 7 deletions

diff --git a/src/lsp.c b/src/lsp.c
index 72ce4d3..2c1f89b 100644
--- a/src/lsp.c
+++ b/src/lsp.c
@@ -918,7 +918,7 @@ teco_lsp_lookup_symbol(teco_string_t str, gboolean match_exact, GError **error)
 	while (sj_iter_object(&reader, obj, &key, &val) &&
 	       !teco_json_eq(key, "result"));
 	sj_Value arr = val;
-	if (arr.type != SJ_ARRAY) {
+	if (arr.type != SJ_NULL && arr.type != SJ_ARRAY) {
 		g_set_error(error, TECO_ERROR, TECO_ERROR_FAILED,
 		            "Expected array in response (at byte %zu)",
 		            arr.start - reader.data);
@@ -962,7 +962,7 @@ teco_lsp_lookup_symbol(teco_string_t str, gboolean match_exact, GError **error)
 		results++;
 	}
 	if (results > 1)
-		teco_interface_msg(TECO_MSG_INFO, "Found %u references", results);
+		teco_interface_msg(TECO_MSG_INFO, "Found %u symbols", results);
 
 	teco_undo_ptr(teco_lsp.current) = (teco_lsp_result_t *)teco_lsp.list.first;
 	return TRUE;
@@ -1013,6 +1013,7 @@ teco_lsp_symbol_auto_complete(const gchar *symbol, teco_string_t *insert)
 	       !teco_json_eq(key, "result"));
 	sj_Value arr = val;
 	if (arr.type != SJ_ARRAY)
+		/* can also be `null` in some LSPs */
 		return FALSE;
 
 	GSList *list = NULL;
@@ -1057,9 +1058,13 @@ teco_lsp_symbol_auto_complete(const gchar *symbol, teco_string_t *insert)
 	} else if (list_len > 1) {
 		list = g_slist_sort(list, (GCompareFunc)strcmp);
 
-		for (GSList *entry = list; entry != NULL; entry = g_slist_next(entry))
-			teco_interface_popup_add(TECO_POPUP_PLAIN, entry->data,
-			                         strlen(entry->data), FALSE);
+		for (GSList *entry = list; entry != NULL; entry = g_slist_next(entry)) {
+			const gchar *name = entry->data;
+			if (g_slist_next(entry) && !strcmp(name, g_slist_next(entry)->data))
+				/* filter out duplicates */
+				continue;
+			teco_interface_popup_add(TECO_POPUP_PLAIN, name, strlen(name), FALSE);
+		}
 
 		teco_interface_popup_show(symbol_len);
 	}
@@ -1111,12 +1116,16 @@ teco_lsp_lookup_definition(teco_buffer_t *buffer, teco_int_t pos, GError **error
 	sj_Value key, val = {0};
 	while (sj_iter_object(&reader, obj, &key, &val) &&
 	       !teco_json_eq(key, "result"));
+	/*
+	 * Some servers can return `null` for an empty list
+	 * or an object for a single result.
+	 */
 	if (val.type == SJ_OBJECT) {
 		teco_lsp_result_t *result = teco_lsp_parse_location(reader, val, error);
 		if (!result)
 			return FALSE;
 		teco_stailq_insert_tail(&teco_lsp.list, &result->entry);
-	} else if (val.type != SJ_ARRAY) {
+	} else if (val.type != SJ_NULL && val.type != SJ_ARRAY) {
 		g_set_error(error, TECO_ERROR, TECO_ERROR_FAILED,
 		            "Expected array in response (at byte %zu)",
 		            val.start - reader.data);
@@ -1186,7 +1195,7 @@ teco_lsp_lookup_references(teco_buffer_t *buffer, teco_int_t pos, GError **error
 	while (sj_iter_object(&reader, obj, &key, &val) &&
 	       !teco_json_eq(key, "result"));
 	sj_Value arr = val;
-	if (arr.type != SJ_ARRAY) {
+	if (arr.type != SJ_NULL && arr.type != SJ_ARRAY) {
 		g_set_error(error, TECO_ERROR, TECO_ERROR_FAILED,
 		            "Expected array in response (at byte %zu)",
 		            arr.start - reader.data);