Add s///r (non-destructive substitution).

This changes s/// so that it doesn't act destructively on its target.
Instead it returns the result of the substitution (or the original string if
there was no match).

In addition this patch:

  * Adds a new warning when s///r happens in void context.
  * Adds a error when you try to use s///r with !~
  * Makes it so constant strings can be bound to s///r with =~
  * Adds documentation.
  * Adds some tests.
  * Updates various debug code so it knows about the /r flag.
  * Adds some new 'r' words to B::Deparse.

1 files changed, 4 insertions, 1 deletions

diff --git a/pp_ctl.c b/pp_ctl.c
index 2408a7b16e..7b94587fd2 100644
--- a/pp_ctl.c
+++ b/pp_ctl.c
@@ -325,7 +325,10 @@ PP(pp_substcont)
 	    SvPV_set(dstr, NULL);
 
 	    TAINT_IF(cx->sb_rxtainted & 1);
-	    mPUSHi(saviters - 1);
+	    if (pm->op_pmflags & PMf_NONDESTRUCT)
+		PUSHs(targ);
+	    else
+		mPUSHi(saviters - 1);
 
 	    (void)SvPOK_only_UTF8(targ);
 	    TAINT_IF(cx->sb_rxtainted);