* data/Makefile.am (dist_pkgdata_DATA): Add bison.m4; this

[bison.git] / NEWS

diff --git a/NEWS b/NEWS
index dd36e633ad222f2632b280e160801978147a8d0a..a970b34ef6ac631f6f5898fec1d0c2271794491c 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -1,7 +1,38 @@
 Bison News
 ----------
 
 Bison News
 ----------
 

-Changes in version 2.3+:
+Changes in version 2.3a, 2006-09-13:
+
+* Instead of %union, you can define and use your own union type
+  YYSTYPE if your grammar contains at least one <type> tag.
+  Your YYSTYPE need not be a macro; it can be a typedef.
+  This change is for compatibility with other Yacc implementations,
+  and is required by POSIX.
+
+* Locations columns and lines start at 1.
+  In accordance with the GNU Coding Standards and Emacs.
+
+* You may now declare per-type and default %destructor's and %printer's:
+
+  For example:
+
+    %union { char *string; }
+    %token <string> STRING1
+    %token <string> STRING2
+    %type  <string> string1
+    %type  <string> string2
+    %union { char character; }
+    %token <character> CHR
+    %type  <character> chr
+    %destructor { free ($$); } %symbol-default
+    %destructor { free ($$); printf ("%d", @$.first_line); } STRING1 string1
+    %destructor { } <character>
+
+  guarantees that, when the parser discards any user-defined symbol that has a
+  semantic type tag other than `<character>', it passes its semantic value to
+  `free'.  However, when the parser discards a `STRING1' or a `string1', it
+  also prints its line number to `stdout'.  It performs only the second
+  `%destructor' in this case, so it invokes `free' only once.

 
 * Except for LALR(1) parsers in C with POSIX Yacc emulation enabled (with `-y',
   `--yacc', or `%yacc'), Bison no longer generates #define statements for
 
 * Except for LALR(1) parsers in C with POSIX Yacc emulation enabled (with `-y',
   `--yacc', or `%yacc'), Bison no longer generates #define statements for


@@ -16,7 +47,7 @@ Changes in version 2.3+:
   `%{ ... %}' syntax.  To generate the pre-prologue, Bison concatenates all
   prologue blocks that you've declared before the first %union.  To generate
   the post-prologue, Bison concatenates all prologue blocks that you've
   `%{ ... %}' syntax.  To generate the pre-prologue, Bison concatenates all
   prologue blocks that you've declared before the first %union.  To generate
   the post-prologue, Bison concatenates all prologue blocks that you've

-  declared after the first %union.  
+  declared after the first %union.

 
   Previous releases of Bison inserted the pre-prologue into both the header
   file and the code file in all cases except for LALR(1) parsers in C.  In the
 
   Previous releases of Bison inserted the pre-prologue into both the header
   file and the code file in all cases except for LALR(1) parsers in C.  In the