From e694dde54a71cad3e2df5b28400aac8c7d564932 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Sat, 2 Jan 2016 09:37:27 -0800
Subject: Use last-form-evaled mechanism for pattern language.

We need this now, since file system errors aren't
handled in the pattern language any more, after
the complex_open refactoring.

* eval.c (set_last_form_evaled): New function.

* eval.h (set_last_form_evaled): Declared.

* match.c (do_match_line, match_files):
Save, set up and restore last_form_evaled
via set_last_form_evaled function.
---
 eval.c  |  7 +++++++
 eval.h  |  1 +
 match.c | 18 ++++++++++++------
 3 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/eval.c b/eval.c
index c754136d..384408af 100644
--- a/eval.c
+++ b/eval.c
@@ -228,6 +228,13 @@ static val set_origin(val form, val origin)
   return form;
 }
 
+val set_last_form_evaled(val form)
+{
+  val prev = last_form_evaled;
+  last_form_evaled = form;
+  return prev;
+}
+
 void error_trace(val exsym, val exvals, val out_stream, val prefix)
 {
   val last = last_form_evaled;
diff --git a/eval.h b/eval.h
index 7edb9eb2..d3e814ad 100644
--- a/eval.h
+++ b/eval.h
@@ -34,6 +34,7 @@ noreturn val eval_error(val ctx, val fmt, ...);
 val ctx_form(val obj);
 val ctx_name(val obj);
 val lookup_origin(val form);
+val set_last_form_evaled(val form);
 void error_trace(val exsym, val exvals, val out_stream, val prefix);
 val make_env(val fbindings, val vbindings, val up_env);
 val copy_env(val oenv);
diff --git a/match.c b/match.c
index cd57e946..3c78e651 100644
--- a/match.c
+++ b/match.c
@@ -1229,21 +1229,20 @@ static val v_fun(match_files_ctx *c);
 
 static val do_match_line(match_line_ctx *c)
 {
+  val lfe_save = set_last_form_evaled(nil);
+
   debug_enter;
 
-  for (;;) {
-    val elem;
+  while (c->specline) {
+    val elem = first(c->specline);
 
-    if (c->specline == nil)
-      break;
+    set_last_form_evaled(elem);
 
     if (c->pos == t)
       c->pos = length_str(c->dataline);
 
     consume_prefix(c);
 
-    elem = first(c->specline);
-
     debug_check(c->specline, c->bindings, c->dataline, c->data_lineno,
                 c->pos, c->base);
 
@@ -1348,6 +1347,8 @@ static val do_match_line(match_line_ctx *c)
 
   debug_return (cons(c->bindings, plus(c->pos, c->base)));
   debug_leave;
+
+  set_last_form_evaled(lfe_save);
 }
 
 static val match_line(match_line_ctx c)
@@ -3882,6 +3883,7 @@ repeat_spec_same_data:
     debug_check(specline, c.bindings, c.data, c.data_lineno, nil, nil);
 
     if (consp(first_spec) && !rest(specline)) {
+      val lfe_save = set_last_form_evaled(first_spec);
       val sym = first(first_spec);
       val entry = gethash(v_directive_table, sym);
 
@@ -3891,6 +3893,8 @@ repeat_spec_same_data:
 
         result = vmf(&c);
 
+        set_last_form_evaled(lfe_save);
+
         if (result == next_spec_k) {
           if ((c.spec = rest(c.spec)) == nil)
             break;
@@ -3903,6 +3907,8 @@ repeat_spec_same_data:
       } else {
         val result = v_fun(&c);
 
+        set_last_form_evaled(lfe_save);
+
         if (result == next_spec_k) {
           if ((c.spec = rest(c.spec)) == nil)
             break;
-- 
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