listener: prompt feature for plain mode.

The :prompt-on command will enable prompting in plain mode.

* linenoise/linenoise.c (struct lino_state): New member, show_prompt.
(line_enable_noninteractive_prompt): New function.
(linenoise): In the plain mode loop, the show_prompt flag is on, show
the prompt. For continuation lines, show a condensed prompt, which
consists of the suffix of the full prompt, starting on the last
non-whitespace character.

* linenoise/linenoise.h (lino_enable_noninteractive): Declared.

* parser.c (repl): Implement :prompt-on command which enables the
above mode.

* txr.1: Documented.

1 files changed, 4 insertions, 0 deletions

diff --git a/parser.c b/parser.c
index 4140f6e6..1653f596 100644
--- a/parser.c
+++ b/parser.c
@@ -1474,6 +1474,7 @@ val repl(val bindings, val in_stream, val out_stream, val env)
   val quit_k = intern(lit("quit"), keyword_package);
   val read_k = intern(lit("read"), keyword_package);
   val prompt_k = intern(lit("prompt"), keyword_package);
+  val prompt_on_k = intern(lit("prompt-on"), keyword_package);
   val p_k = intern(lit("p"), keyword_package);
   val save_k = intern(lit("save"), keyword_package);
   val counter_sym = intern(lit("*n"), user_package);
@@ -1599,6 +1600,9 @@ val repl(val bindings, val in_stream, val out_stream, val env)
       } else if (form == prompt_k) {
         pprinl(prompt, out_stream);
         counter = prev_counter;
+      } else if (form == prompt_on_k) {
+        lino_enable_noninteractive_prompt(ls, 1);
+        counter = prev_counter;
       } else if (form == p_k) {
         pprinl(prev_counter, out_stream);
         counter = prev_counter;