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, 5 insertions, 4 deletions

diff --git a/toke.c b/toke.c
index 6cb33c1e3f..f142ada83f 100644
--- a/toke.c
+++ b/toke.c
@@ -11826,10 +11826,11 @@ static U32
 S_pmflag(U32 pmfl, const char ch) {
     switch (ch) {
 	CASE_STD_PMMOD_FLAGS_PARSE_SET(&pmfl);
-    case GLOBAL_PAT_MOD:    pmfl |= PMf_GLOBAL; break;
-    case CONTINUE_PAT_MOD:  pmfl |= PMf_CONTINUE; break;
-    case ONCE_PAT_MOD:      pmfl |= PMf_KEEP; break;
-    case KEEPCOPY_PAT_MOD:  pmfl |= PMf_KEEPCOPY; break;
+    case GLOBAL_PAT_MOD:      pmfl |= PMf_GLOBAL; break;
+    case CONTINUE_PAT_MOD:    pmfl |= PMf_CONTINUE; break;
+    case ONCE_PAT_MOD:        pmfl |= PMf_KEEP; break;
+    case KEEPCOPY_PAT_MOD:    pmfl |= PMf_KEEPCOPY; break;
+    case NONDESTRUCT_PAT_MOD: pmfl |= PMf_NONDESTRUCT; break;
     }
     return pmfl;
 }