support lookups via language servers (LSP)HEADmaster-fmsbw-cimaster

* The main interface is the `FT` command.
  `FT` was an undocumented Video TECO command for etags/ctags lookups.
  I don't want to exactly copy its interface, though.
* `FT` allows looking up symbol names,
  definitions and references.
* ctags will be supported via ctags-lsp.
  LSP support is more powerful though and works without
  regenerating TAGS files all the time.
  The LSP will also allow you to customize auto-completions
  using SciTECO itself (i.e. by writing a language server
  in SciTECO).
* For multiple results, `FT$` can be used to cycle through
  results - this should mimic repeated `S$` or `N$`.
* `:FT...$` does a fuzzy search. IMHO it's not important
  to return a status integer instead. `FT` will only
  really be used in interactive mode.
* Document synchronization is supported via hooks from
  ring.c and via Scintilla notifications.
* Currently, the LSP communication is based on blocking
  GIOChannels. This means that a misbehaving hanging
  server could "lock up" the entire editor (FIXME).
  Only on ncurses you can always kill the subprocess by
  pressing CTRL+C.
  We need helper functions in spawn.c to read and write
  with interruptions.
* The textDocument/didChange notification transmits
  not only all edits, but all files' contents as well
  during initial synchronization.
  Therefore it is optimized to write and JSON-escape
  data without copying them around in memory and without
  destroying the buffer gap.
* Use $SCITECO_LSP to configure the language server.
  You can also use `tee` to capture stdin and stdout.
  Perhaps $SCITECO_LSP should be saved in .teco_session,
  so you can change it between projects?
* $SCITECO_LSP_ROOT is used to point to the project's
  root directory. session.tes will set it up automatically.

1 files changed, 8 insertions, 0 deletions

diff --git a/src/ring.h b/src/ring.h
index 91ce3c9..126f455 100644
--- a/src/ring.h
+++ b/src/ring.h
@@ -44,6 +44,12 @@ typedef struct teco_buffer_t {
 	gchar *filename;
 
 	/**
+	 * Counter increasing with every change.
+	 * It is maintained only if a language server (LSP) is running.
+	 */
+	guint version;
+
+	/**
 	 * A teco_buffer_state_t.
 	 * This is still a guint, so you can call teco_undo_guint().
 	 */
@@ -117,6 +123,8 @@ void teco_ring_undo_close(void);
 
 void teco_ring_set_scintilla_undo(gboolean state);
 
+gboolean teco_ring_sync_lsp(GError **error);
+
 void teco_ring_cleanup(void);
 
 /*