From b81a5285f8b9b583c6933e7aa576f3ef0a3a8e82 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Fri, 18 Dec 2015 22:31:30 -0800
Subject: Print some instances of qref as dot notation.

We must preserve ambiguity-free read-print consistency.

* lib.c (simple_qref_args_p): New static function.
(obj_print_impl): Check for qref and print as
dot notation if its argument list satisfies
simple_qref_args_p.
---
 lib.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

(limited to 'lib.c')

diff --git a/lib.c b/lib.c
index 7b5df796..05ccb45a 100644
--- a/lib.c
+++ b/lib.c
@@ -8124,6 +8124,21 @@ static void obj_init(void)
   prog_string = string(progname);
 }
 
+static val simple_qref_args_p(val args, val pos)
+{
+  if (nilp(args)) {
+    return if2(ge(pos, two), t);
+  } else if (!consp(args)) {
+    return nil;
+  } else {
+    val arg = car(args);
+    if (symbolp(arg) || (consp(arg) && car(arg) != qref_s)) {
+      return simple_qref_args_p(cdr(args), succ(pos));
+    }
+    return nil;
+  }
+}
+
 val obj_print_impl(val obj, val out, val pretty)
 {
   val ret = obj;
@@ -8174,6 +8189,15 @@ val obj_print_impl(val obj, val out, val pretty)
         obj_print_impl(second(obj), out, pretty);
         put_string(lit(".."), out);
         obj_print_impl(third(obj), out, pretty);
+      } else if (sym == qref_s && simple_qref_args_p(cdr(obj), zero)) {
+        val iter, next;
+        for (iter = cdr(obj); iter; iter = next) {
+          next = cdr(iter);
+          obj_print_impl(car(iter), out, pretty);
+          if (next)
+            put_string(lit("."), out);
+          iter = next;
+        }
       } else {
         val iter;
         val closepar = chr(')');
-- 
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