Send changes immediately instead of queueing them

For incremental change mode, all the changes in a `textDocument/didChange`
message are interpreted as applying to the same version of a particular
document.

But each emacs change corresponds to the state of the document when the change
happens. So harmonise the expectations by sending each change in its own
message.

closes emacs-lsp#112

Author: alanz

lsp-methods.el

@@ -802,15 +802,22 @@ to a text document."
     ;;
     ;; So (47 54 0) means add    7 chars starting at pos 47
     ;; So (47 47 7) means delete 7 chars starting at pos 47
-    ;; (message "lsp-on-change:(start,end,length)=(%s,%s,%s)" start end length)
+  ;; (message "lsp-on-change:(start,end,length)=(%s,%s,%s)" start end length)
   (lsp--flush-other-workspace-changes)
   (when (and lsp--cur-workspace
           (not (or (eq lsp--server-sync-method 'none)
                  (eq lsp--server-sync-method nil))))
     (setq lsp--has-changes t)
     (lsp--rem-idle-timer)
     (when (eq lsp--server-sync-method 'incremental)
-      (lsp--push-change (lsp--text-document-content-change-event start end length)))
+      ;; (lsp--push-change (lsp--text-document-content-change-event start end length)))
+
+      ;; Each change needs to be wrt to the current doc, so send immediately.
+      ;; Otherwise we need to adjust the coordinates of the new change according
+      ;; to the cumulative changes already queued.
+      (progn
+        (lsp--push-change (lsp--text-document-content-change-event start end length))
+        (lsp--send-changes lsp--cur-workspace)))
     (if (lsp--workspace-change-timer-disabled lsp--cur-workspace)
       (lsp--send-changes lsp--cur-workspace)
       (lsp--set-idle-timer lsp--cur-workspace))))