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[bison.git] / NEWS

diff --git a/NEWS b/NEWS
index 96cfa7a773830c03ccf49634cf384e430031ebda..3526e7b46c0b22cf53e7c90b7f15ad806f1cfbde 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -3,7 +3,52 @@ Bison News
 
 Changes in version 2.3a+ (????-??-??):
 
 
 Changes in version 2.3a+ (????-??-??):
 

-* Previously, Bison sometimes generated parser tables containing unreachable
+* The quotes around NAME that used to be required in the following directive
+  are now deprecated:
+
+    %define NAME "VALUE"
+
+* The directive `%pure-parser' is now deprecated in favor of:
+
+    %define api.pure
+
+  which has the same effect except that Bison is more careful to warn about
+  unreasonable usage in the latter case.
+
+* Push Parsing
+
+  Bison can now generate an LALR(1) parser in C with a push interface.  That
+  is, instead of invoking `yyparse', which pulls tokens from `yylex', you can
+  push one token at a time to the parser using `yypush_parse', which will
+  return to the caller after processing each token.  By default, the push
+  interface is disabled.  Either of the following directives will enable it:
+
+    %define api.push_pull "push" // Just push; does not require yylex.
+    %define api.push_pull "both" // Push and pull; requires yylex.
+
+  See the new section `A Push Parser' in the Bison manual for details.
+
+* The -g and --graph options now output graphs in Graphviz DOT format,
+  not VCG format.
+
+* An experimental directive %language specifies the language of the
+  generated parser, which can be C (the default) or C++.  This
+  directive affects the skeleton used, and the names of the generated
+  files if the grammar file's name ends in ".y".
+
+* The grammar file may now specify the name of the parser header file using
+  %defines.  For example:
+
+    %defines "parser.h"
+
+* When reporting useless rules, useless nonterminals, and unused terminals,
+  Bison now employs the terms "useless in grammar" instead of "useless",
+  "useless in parser" instead of "never reduced", and "unused in grammar"
+  instead of "unused".
+
+* Unreachable State Removal
+
+  Previously, Bison sometimes generated parser tables containing unreachable

   states.  A state can become unreachable during conflict resolution if Bison
   disables a shift action leading to it from a predecessor state.  Bison now:
 
   states.  A state can become unreachable during conflict resolution if Bison
   disables a shift action leading to it from a predecessor state.  Bison now:
 


@@ -14,7 +59,7 @@ Changes in version 2.3a+ (????-??-??):
        directives in existing grammar files.
 
     3. For any rule used only in such states, Bison now reports the rule as
        directives in existing grammar files.
 
     3. For any rule used only in such states, Bison now reports the rule as

-       "never reduced because of conflicts".
+       "useless in parser due to conflicts".

 
   This feature can be disabled with the following directive:
 
 
   This feature can be disabled with the following directive:
 


@@ -23,7 +68,9 @@ Changes in version 2.3a+ (????-??-??):
   See the %define entry in the `Bison Declaration Summary' in the Bison manual
   for further discussion.
 
   See the %define entry in the `Bison Declaration Summary' in the Bison manual
   for further discussion.
 

-* When instructed to generate a `.output' file including lookahead sets
+* Lookahead Set Correction in the `.output' Report
+  
+  When instructed to generate a `.output' file including lookahead sets

   (using `--report=lookahead', for example), Bison now prints each reduction's
   lookahead set only next to the associated state's one item that (1) is
   associated with the same rule as the reduction and (2) has its dot at the end
   (using `--report=lookahead', for example), Bison now prints each reduction's
   lookahead set only next to the associated state's one item that (1) is
   associated with the same rule as the reduction and (2) has its dot at the end


@@ -32,18 +79,7 @@ Changes in version 2.3a+ (????-??-??):
   bug affected only the `.output' file and not the generated parser source
   code.
 
   bug affected only the `.output' file and not the generated parser source
   code.
 

-* The -g and --graph options now output graphs in Graphviz DOT format,
-  not VCG format.
-
-* An experimental directive %language specifies the language of the
-  generated parser, which can be C (the default) or C++.  This
-  directive affects the skeleton used, and the names of the generated
-  files if the grammar file's name ends in ".y".
-
-* The grammar file may now specify the name of the parser header file using
-  %defines.  For example:
-
-    %defines "parser.h"
+* --report-file=FILE is a new flag to override the default `.output' file name.

 
 * The `=' that used to be required in the following directives is now
   deprecated:
 
 * The `=' that used to be required in the following directives is now
   deprecated:


@@ -52,12 +88,9 @@ Changes in version 2.3a+ (????-??-??):
     %name-prefix "c_"
     %output "parser.c"
 
     %name-prefix "c_"
     %output "parser.c"
 

-* The quotes around NAME that used to be required in the following directive
-  are now deprecated:
+* An Alternative to `%{...%}' -- `%code QUALIFIER {CODE}'

 
 

-    %define NAME "VALUE"
-
-* Bison 2.3a provided a new set of directives as a more flexible alternative to
+  Bison 2.3a provided a new set of directives as a more flexible alternative to

   the traditional Yacc prologue blocks.  Those have now been consolidated into
   a single %code directive with an optional qualifier field, which identifies
   the purpose of the code and thus the location(s) where Bison should generate
   the traditional Yacc prologue blocks.  Those have now been consolidated into
   a single %code directive with an optional qualifier field, which identifies
   the purpose of the code and thus the location(s) where Bison should generate


@@ -96,7 +129,9 @@ Changes in version 2.3a+ (????-??-??):
   To enable these warnings, specify the flag `--warnings=midrule-values' or
   `-W', which is a synonym for `--warnings=all'.
 
   To enable these warnings, specify the flag `--warnings=midrule-values' or
   `-W', which is a synonym for `--warnings=all'.
 

-* Bison now recognizes two separate kinds of default %destructor's and
+* Default %destructor or %printer with `<*>' or `<>'
+
+  Bison now recognizes two separate kinds of default %destructor's and

   %printer's:
 
     1. Place `<*>' in a %destructor/%printer symbol list to define a default
   %printer's:
 
     1. Place `<*>' in a %destructor/%printer symbol list to define a default