* eval.c (eval_init): Registered regex_parse as new

intrinsic function and std_null as new variable.

* parser.h (yylex_destroy): Existing function declared.

* parser.l (regex_parse): New function.
New lexical syntax added which returns SECRET_ESCAPE_R.

* parser.y (SECRET_ESCAPE_R): New token.
(spec): Added syntactic variant which lets us
smuggle a regex into the parser easily.

* stream.c:x (std_null): New global variable.
(null_stream_print): New static function.
(null_ops): New static structure.
(make_null_stream): New function.
(stream_init): Protect and initialize std_null.

* stream.h (std_null, make_null_stream): Declared.

* txr.1: New features documented: regex-parse, *stdnull*.

* txr.c (txr_main): Call yylex_destroy after parsing the program now
that I know about this function; this can free up some memory.

1 files changed, 25 insertions, 0 deletions

diff --git a/parser.l b/parser.l
index c629e481..18b4af3b 100644
--- a/parser.l
+++ b/parser.l
@@ -675,6 +675,11 @@ UONLY   {U2}{U}|{U3}{U}{U}|{U4}{U}{U}{U}
   yy_push_state(SPECIAL);
 }
 
+<INITIAL>@\x01R {
+  yy_push_state(REGEX);
+  return SECRET_ESCAPE_R;
+}
+
 <INITIAL>^@[#;].*\n {
   /* eat whole line comment */
   lineno++;
@@ -823,3 +828,23 @@ void parse_reset(val spec_file)
     yyin_stream = make_stdio_stream(in, spec_file_str);
   }
 }
+
+val regex_parse(val string, val error_stream)
+{
+  uses_or2;
+  val parse_string = cat_str(list(lit("@\x01R/"), string, lit("/"), nao), nil);
+  yyin_stream = make_string_byte_input_stream(parse_string);
+  errors = 0;
+  lineno = 1;
+  val save_stream = std_error;
+  std_error = if3(error_stream == t, std_output, or2(error_stream, std_null));
+  {
+    int gc = gc_state(0);
+    spec_file_str = string;
+    yyparse();
+    yylex_destroy();
+    gc_state(gc);
+  }
+  std_error = save_stream;
+  return errors ? nil : rest(get_spec());
+}