LSP: auto-complete symbols via the textDocument/completion request

This currently only works in insert commands after enabling the immediate
editing modifier via CTRL+G and if the LSP was already launched
(e.g. by an explicit `FT$`).
File name completions are still performed with an activated ^G modifier
only if the LSP is shut down.

Just like for file names, the modifier is automatically cancelled after
a successful completion - there is little sense in completing several
symbols in a row.

1 files changed, 21 insertions, 1 deletions

diff --git a/src/cmdline.c b/src/cmdline.c
index a4e2189..1abf8df 100644
--- a/src/cmdline.c
+++ b/src/cmdline.c
@@ -911,8 +911,28 @@ teco_state_insert_process_edit_cmd(teco_machine_main_t *ctx, teco_machine_t *par
 		return stringbuilding_current->process_edit_cmd_cb(&stringbuilding_ctx->parent, &ctx->parent, key, error);
 
 	switch (key) {
-	case '\t': { /* insert <TAB> indention */
+	case '\t': { /* insert <TAB> indention or auto complete */
+		if (teco_cmdline.modifier_enabled && !teco_qreg_current && teco_lsp_is_running()) {
+			if (teco_interface_popup_is_shown()) {
+				/* cycle through popup pages */
+				teco_interface_popup_scroll();
+				return TRUE;
+			}
+
+			g_auto(teco_string_t) new_chars, new_chars_escaped;
+			gboolean unambiguous = teco_lsp_buffer_auto_complete(teco_ring_current, &new_chars);
+			teco_machine_stringbuilding_escape(stringbuilding_ctx, new_chars.data,
+			                                   new_chars.len, &new_chars_escaped);
+			if (unambiguous) {
+				teco_string_append_c(&new_chars_escaped, ' ');
+				teco_cmdline_modifier_set(FALSE);
+			}
+
+			return teco_cmdline_insert(new_chars_escaped.data, new_chars_escaped.len, error);
+		}
+
 		if (teco_cmdline.modifier_enabled || teco_interface_ssm(SCI_GETUSETABS, 0, 0))
+			/* perhaps auto-complete file name */
 			break;
 
 		teco_interface_popup_clear();