string-extend: third optional argument.

A Boolean optional argument to string-extend indicates whether
this is likely the last call to string-extend, so memory can
be trimmed accordingly.

* eval.c (eval_init): Update string-extend registration.

* filter.c (trie_filter_string): Pass nil for new argument of
string_extend.

* lib.c (str_seq, replace_str,
lazy_str_force, lazy_str_force_upto): Pass nil for new
argument of string_extend.
(rem_impl, remove_if, separate): Pass t for new argument of
string_extend on last iteration, nil otherwise.
(string_extend): Implement new third argument, defaulted to
nil. Switch from chk_grow_vec to the more specific chk_wrealloc,
which simplifies the code.

* lib.h (string_extend): Declaration updated.

* parser.y (litchars): Pass t as last argument of
string_extend since we know syntactically that these
reductions finalize the string.
(restlitchar): Pass nil as the last argument of string_extend,
since we know syntactically that it isn't the last.

* regex.c (scan_until_common): Pass nil for new argument of
string_extend.

* txr.1: Documented.

1 files changed, 4 insertions, 4 deletions

diff --git a/parser.y b/parser.y
index efc2bd3c..9bac3254 100644
--- a/parser.y
+++ b/parser.y
@@ -1434,15 +1434,15 @@ quasi_item : litchars           { $$ = $1; }
 
 litchars : LITCHAR              { $$ = mkstring(one, chr($1)); }
          | LITCHAR restlitchar  { val ch = mkstring(one, chr($1));
-                                  $$ = string_extend(ch, $2); }
+                                  $$ = string_extend(ch, $2, t); }
          | TEXT                 { $$ = string_own($1); }
-         | TEXT restlitchar     { $$ = string_extend(string_own($1), $2); }
+         | TEXT restlitchar     { $$ = string_extend(string_own($1), $2, t); }
          ;
 
 restlitchar : LITCHAR                   { $$ = mkstring(one, chr($1)); }
-            | restlitchar LITCHAR       { $$ = string_extend($1, chr($2)); }
+            | restlitchar LITCHAR       { $$ = string_extend($1, chr($2), nil); }
             | TEXT                      { $$ = string_own($1); }
-            | restlitchar TEXT          { $$ = string_extend($1, string_own($2)); }
+            | restlitchar TEXT          { $$ = string_extend($1, string_own($2), nil); }
             ;
 
 wordslit : '"'                  { $$ = nil; }