regsub: allow string in place of regex.

* regex.c (regsub): Use search_str if regex is a string.

* txr.1: Documented.

2 files changed, 24 insertions, 4 deletions

diff --git a/regex.c b/regex.c
index 0c2d7940..b2e24b56 100644
--- a/regex.c
+++ b/regex.c
@@ -2898,9 +2898,20 @@ val regsub(val regex, val repl, val str)
   } else {
     val pos = zero;
     val out = mkustring(zero);
+    val slen = if2(stringp(regex), length(regex));
 
     do {
-      cons_bind (find, len, search_regex(str, regex, pos, nil));
+      val find, len;
+
+      if (slen) {
+        len = slen;
+        find = search_str(str, regex, pos, nil);
+      } else {
+        cons_bind (a, d, search_regex(str, regex, pos, nil));
+        find = a;
+        len = d;
+      }
+
       if (!find) {
         if (pos == zero)
           return str;
diff --git a/txr.1 b/txr.1
index 475a814d..775a6085 100644
--- a/txr.1
+++ b/txr.1
@@ -53100,7 +53100,9 @@ and
 
 .coNP Function @ regsub
 .synb
-.mets (regsub >> { regex | << function } < replacement << string )
+.mets (regsub < regex < replacement << string )
+.mets (regsub < substring < replacement << string )
+.mets (regsub < function < replacement << string )
 .syne
 .desc
 The
@@ -53109,10 +53111,14 @@ function operates in two modes, depending on whether
 the first argument is a regular expression,
 or function.
 
-If the first argument is a regular expression it searches
+If the first argument is a regular expression or string, then
+.code regsub
+searches
 .meta string
 for multiple occurrences of non-overlapping matches for that
-.metn regex .
+.meta regex
+or
+.metn substring .
 A new string is constructed
 similar to
 .meta string
@@ -53156,6 +53162,9 @@ which indicates that no replacement is to take place.
   ;; Replace Hello with Goodbye:
   (regsub #/Hello/ "Goodbye" "Hello world!") -> "Goodbye world!"
 
+  ;; Same, as a simple substring match, rather than regex:
+  (regsub "Hello" "Goodbye" "Hello world!") -> "Goodbye world!"
+
   ;; Left-anchored replacement with r^ function:
   (regsub (fr^ #/H/) "J" "Hello, hello!") -> "Jello, hello!"
 .brev