From fb96a3ee7732129d0ee475d7d8438aeffe39d80e Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Sun, 4 Mar 2012 18:34:13 -0800
Subject: * eval.c (eval_init): New intrinsic function, regsub.

* regex.c (regsub): New function.

* regex.h (regsub): Declared.

* txr.1: Doc stub added.
---
 ChangeLog | 10 ++++++++++
 eval.c    |  1 +
 regex.c   | 28 ++++++++++++++++++++++++++++
 regex.h   |  1 +
 txr.1     |  2 ++
 5 files changed, 42 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index 9accc1f8..a26863dd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2012-03-04  Kaz Kylheku  <kaz@kylheku.com>
+
+	* eval.c (eval_init): New intrinsic function, regsub.
+
+	* regex.c (regsub): New function.
+
+	* regex.h (regsub): Declared.
+
+	* txr.1: Doc stub added.
+
 2012-03-04  Kaz Kylheku  <kaz@kylheku.com>
 
 	* lib.c (split_str): Separator can be a regex now.
diff --git a/eval.c b/eval.c
index 76985a67..0a9f9765 100644
--- a/eval.c
+++ b/eval.c
@@ -2178,6 +2178,7 @@ void eval_init(void)
 
   reg_fun(intern(lit("search-regex"), user_package), func_n4o(search_regex, 2));
   reg_fun(intern(lit("match-regex"), user_package), func_n3o(match_regex, 2));
+  reg_fun(intern(lit("regsub"), user_package), func_n3(regsub));
 
   reg_fun(intern(lit("make-hash"), user_package), func_n3(make_hash));
   reg_fun(intern(lit("hash"), user_package), func_n0v(hashv));
diff --git a/regex.c b/regex.c
index 2ad5a5cb..6c2a914d 100644
--- a/regex.c
+++ b/regex.c
@@ -1723,3 +1723,31 @@ val match_regex(val str, val reg, val pos)
 
   return nil;
 }
+
+val regsub(val str, val regex, val repl)
+{
+  list_collect_decl (out, ptail);
+  val pos = zero;
+
+  do {
+    cons_bind (find, len, search_regex(str, regex, pos, nil));
+    if (!find) {
+      if (pos == zero)
+        return str;
+      list_collect(ptail, sub_str(str, pos, nil));
+      break;
+    }
+    list_collect(ptail, sub_str(str, pos, find));
+    list_collect(ptail, repl);
+    if (len == zero && eql(find, pos)) {
+      if (lt(pos, length_str(str))) {
+        list_collect(ptail, chr_str(str, pos));
+        pos = plus(pos, one);
+      }
+    } else {
+      pos = plus(find, len);
+    }
+  } while (lt(pos, length_str(str)));
+
+  return cat_str(out, nil);
+}
diff --git a/regex.h b/regex.h
index c983142a..a5911790 100644
--- a/regex.h
+++ b/regex.h
@@ -28,3 +28,4 @@ val regex_compile(val regex_sexp);
 val regexp(val);
 val search_regex(val haystack, val needle_regex, val start_num, val from_end);
 val match_regex(val str, val regex, val pos);
+val regsub(val str, val regex, val repl);
diff --git a/txr.1 b/txr.1
index f5f9fbbe..070960ba 100644
--- a/txr.1
+++ b/txr.1
@@ -6518,6 +6518,8 @@ Certain object types have a custom equal function.
 
 .SS Functions search-regex and match-regex
 
+.SS Function regsub
+
 .SS Functions make-hash, hash
 
 .SS Function sethash
-- 
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