From 563b6367a572bc50f8fbec2aeff255c258407862 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Sat, 21 Feb 2015 06:07:57 -0800
Subject: Improved error reporting, particularly for macro expansion.

* eval.c (last_form_expanded): New variable.
(do_expand): New static function; contains previous expand
function.
(expand): Becomes a wrapper for do_expand, with re-entry
counting.
(eval_init): GC-protect last_form_expanded.

* eval.h (last_form_expanded): Declared.

* parser.l (regex_parse, lisp_parse): Just use a simple word for
the name of the regex or string parse location, not the entire
expression itself.

* unwind.c (uw_throw): Check whether expansion was going on
when the unhandled exception was thrown and print additional
information.
---
 eval.c | 29 ++++++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

(limited to 'eval.c')

diff --git a/eval.c b/eval.c
index 5721aa85..dce7e949 100644
--- a/eval.c
+++ b/eval.c
@@ -87,7 +87,7 @@ val opip_s, oand_s, chain_s, chand_s;
 
 val special_s, whole_k, symacro_k, fun_k;
 
-val last_form_evaled;
+val last_form_evaled, last_form_expanded;
 
 val call_f;
 
@@ -2806,7 +2806,7 @@ static val expand_save_specials(val form, val specials)
   return rlcp(cons(with_saved_vars_s, cons(form, nil)), form);
 }
 
-val expand(val form, val menv)
+static val do_expand(val form, val menv)
 {
   val macro = nil;
 
@@ -3023,6 +3023,28 @@ tail:
   }
 }
 
+val expand(val form, val menv)
+{
+  val ret = nil;
+  static int reentry_count;
+
+  uw_simple_catch_begin;
+
+  reentry_count++;
+
+  last_form_expanded = form;
+  ret = do_expand(form, menv);
+
+  uw_unwind {
+    if (--reentry_count == 0)
+      last_form_expanded = nil;
+  }
+
+  uw_catch_end;
+
+  return ret;
+}
+
 static val macro_form_p(val form, val menv)
 {
   menv = default_bool_arg(menv);
@@ -3675,7 +3697,8 @@ static val merge_wrap(val seq1, val seq2, val lessfun, val keyfun)
 void eval_init(void)
 {
   protect(&top_vb, &top_fb, &top_mb, &top_smb, &special, &dyn_env,
-          &op_table, &last_form_evaled, &call_f, convert(val *, 0));
+          &op_table, &last_form_evaled, &last_form_expanded,
+          &call_f, convert(val *, 0));
   top_fb = make_hash(t, nil, nil);
   top_vb = make_hash(t, nil, nil);
   top_mb = make_hash(t, nil, nil);
-- 
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