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doc: cleanup.

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* NEWS (2.5): Make some minor improvements to wording, and format
entries more consistently.
* doc/bison.texinfo (Language and Grammar): Point out that IELR
and canonical LR are experimental features.
(Decl Summary): In list of %define variables, make wording more
consistent.  Improve discussion of using LALR for GLR.
This commit is contained in:
Joel E. Denny
2010-12-19 22:14:08 -05:00
parent fcf834f9ec
commit f1b238df18
3 changed files with 44 additions and 30 deletions
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10
ChangeLog
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@@ -1,3 +1,13 @@
2010-12-19 Joel E. Denny <jdenny@clemson.edu>
doc: cleanup.
* NEWS (2.5): Make some minor improvements to wording, and format
entries more consistently.
* doc/bison.texinfo (Language and Grammar): Point out that IELR
and canonical LR are experimental features.
(Decl Summary): In list of %define variables, make wording more
consistent. Improve discussion of using LALR for GLR.
2010-12-19 Joel E. Denny <jdenny@clemson.edu> 2010-12-19 Joel E. Denny <jdenny@clemson.edu>
parse.lac: document. parse.lac: document.

44
NEWS
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@@ -62,7 +62,7 @@ Bison News
* Changes in version 2.5 (????-??-??): * Changes in version 2.5 (????-??-??):
** Named References Support ** Named references:
Historically, Yacc and Bison have supported positional references Historically, Yacc and Bison have supported positional references
($n, $$) to allow access to symbol values from inside of semantic ($n, $$) to allow access to symbol values from inside of semantic
@@ -87,13 +87,13 @@ Bison News
These features are experimental in this version. More user feedback These features are experimental in this version. More user feedback
will help to stabilize them. will help to stabilize them.
** IELR(1) and Canonical LR(1) Support ** IELR(1) and canonical LR(1):
IELR(1) is a minimal LR(1) parser table generation algorithm. That IELR(1) is a minimal LR(1) parser table generation algorithm. That
is, given any context-free grammar, IELR(1) generates parser tables is, given any context-free grammar, IELR(1) generates parser tables
with the full language recognition power of canonical LR(1) but with with the full language recognition power of canonical LR(1) but with
nearly the same number of parser states as LALR(1). This reduction in nearly the same number of parser states as LALR(1). This reduction
parser states is often an order of magnitude. More importantly, in parser states is often an order of magnitude. More importantly,
because canonical LR(1)'s extra parser states may contain duplicate because canonical LR(1)'s extra parser states may contain duplicate
conflicts in the case of non-LR(1) grammars, the number of conflicts conflicts in the case of non-LR(1) grammars, the number of conflicts
for IELR(1) is often an order of magnitude less as well. This can for IELR(1) is often an order of magnitude less as well. This can
@@ -157,15 +157,15 @@ Bison News
LAC is an experimental feature. More user feedback will help to LAC is an experimental feature. More user feedback will help to
stabilize it. stabilize it.
** Unrecognized %code qualifiers are now an error not a warning. ** Unrecognized %code qualifiers are now errors not warnings.
** %define improvements. ** %define improvements:
*** Unrecognized variables are now an error not a warning. *** Unrecognized variables are now errors not warnings.
*** Multiple invocations for any variable is now an error not a warning. *** Multiple invocations for any variable is now an error not a warning.
*** Can now be invoked via the command line. *** Can now be invoked via the command line:
Each of these command-line options Each of these command-line options
@@ -184,7 +184,7 @@ Bison News
quietly override %define, but -D and --define do not. For further quietly override %define, but -D and --define do not. For further
details, see the section "Bison Options" in the Bison manual. details, see the section "Bison Options" in the Bison manual.
*** Variables renamed. *** Variables renamed:
The following %define variables The following %define variables
@@ -199,7 +199,7 @@ Bison News
The old names are now deprecated but will be maintained indefinitely The old names are now deprecated but will be maintained indefinitely
for backward compatibility. for backward compatibility.
*** Values no longer need to be quoted in grammar file. *** Values no longer need to be quoted in grammar file:
If a %define value is an identifier, it no longer needs to be placed If a %define value is an identifier, it no longer needs to be placed
within quotations marks. For example, within quotations marks. For example,
@@ -210,15 +210,15 @@ Bison News
%define api.push-pull push %define api.push-pull push
** Symbol names. ** Grammar symbol names can now contain dashes:
Consistently with directives (such as %error-verbose) and variables Consistently with directives (such as %error-verbose) and variables
(e.g. push-pull), symbol names may include dashes in any position, (e.g. push-pull), grammar symbol names may include dashes in any
similarly to periods and underscores. This is GNU extension over position, similarly to periods and underscores. This is GNU
POSIX Yacc whose use is reported by -Wyacc, and rejected in Yacc extension over POSIX Yacc whose use is reported by -Wyacc, and
mode (--yacc). rejected in Yacc mode (--yacc).
** YYFAIL now produces warnings and Java parsers no longer implement it. ** YYFAIL now produces warnings and Java parsers no longer implement it:
YYFAIL has existed for many years as an undocumented feature of YYFAIL has existed for many years as an undocumented feature of
deterministic parsers in C generated by Bison. More recently, it was deterministic parsers in C generated by Bison. More recently, it was
@@ -229,7 +229,7 @@ Bison News
discussion of how to suppress C preprocessor warnings about YYFAIL discussion of how to suppress C preprocessor warnings about YYFAIL
being unused, see the Bison 2.4.2 NEWS entry. being unused, see the Bison 2.4.2 NEWS entry.
** Temporary hack for adding a semicolon to the user action. ** Temporary hack for adding a semicolon to the user action:
Previously, Bison appended a semicolon to every user action for Previously, Bison appended a semicolon to every user action for
reductions when the output language defaulted to C (specifically, when reductions when the output language defaulted to C (specifically, when
@@ -250,7 +250,7 @@ Bison News
about a missing semicolon where it did not before. Future releases of about a missing semicolon where it did not before. Future releases of
Bison will cease to append semicolons entirely. Bison will cease to append semicolons entirely.
** Character literals not of length one. ** Character literals not of length one:
Previously, Bison quietly converted all character literals to length Previously, Bison quietly converted all character literals to length
one. For example, without warning, Bison interpreted the operators in one. For example, without warning, Bison interpreted the operators in
@@ -261,7 +261,7 @@ Bison News
; ;
Bison now warns when a character literal is not of length one. In Bison now warns when a character literal is not of length one. In
some future release, Bison will report an error instead. some future release, Bison will start reporting an error instead.
** Verbose syntax error message fixes: ** Verbose syntax error message fixes:
@@ -301,14 +301,14 @@ Bison News
canonical LR. However, LAC is still experimental and is disabled canonical LR. However, LAC is still experimental and is disabled
by default. by default.
** Destructor calls fixed for lookaheads altered in semantic actions. ** Destructor calls fixed for lookaheads altered in semantic actions:
Previously for deterministic parsers in C, if a user semantic action Previously for deterministic parsers in C, if a user semantic action
altered yychar, the parser in some cases used the old yychar value to altered yychar, the parser in some cases used the old yychar value to
determine which destructor to call for the lookahead upon a syntax determine which destructor to call for the lookahead upon a syntax
error or upon parser return. This bug has been fixed. error or upon parser return. This bug has been fixed.
** C++ parsers use YYRHSLOC ** C++ parsers use YYRHSLOC:
Similarly to the C parsers, the C++ parsers now define the YYRHSLOC Similarly to the C parsers, the C++ parsers now define the YYRHSLOC
macro and use it in the default YYLLOC_DEFAULT. You are encouraged macro and use it in the default YYLLOC_DEFAULT. You are encouraged
@@ -343,7 +343,7 @@ Bison News
} \ } \
while (false) while (false)
** YYLLOC_DEFAULT in C++ ** YYLLOC_DEFAULT in C++:
The default implementation of YYLLOC_DEFAULT used to be issued in The default implementation of YYLLOC_DEFAULT used to be issued in
the header file. It is now output in the implementation file, after the header file. It is now output in the implementation file, after

20
doc/bison.texinfo
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@@ -477,8 +477,8 @@ For historical reasons, Bison by default is limited by the additional
restrictions of @acronym{LALR}(1), which is hard to explain simply. restrictions of @acronym{LALR}(1), which is hard to explain simply.
@xref{Mystery Conflicts, ,Mysterious Reduce/Reduce Conflicts}, for @xref{Mystery Conflicts, ,Mysterious Reduce/Reduce Conflicts}, for
more information on this. more information on this.
To escape these additional restrictions, you can request As an experimental feature, you can escape these additional restrictions by
@acronym{IELR}(1) or canonical @acronym{LR}(1) parser tables. requesting @acronym{IELR}(1) or canonical @acronym{LR}(1) parser tables.
@xref{Decl Summary,,lr.type}, to learn how. @xref{Decl Summary,,lr.type}, to learn how.
@cindex @acronym{GLR} parsing @cindex @acronym{GLR} parsing
@@ -5077,7 +5077,7 @@ Some of the accepted @var{variable}s are:
@itemize @itemize
@item Languages(s): C++ @item Languages(s): C++
@item Purpose: Specifies the namespace for the parser class. @item Purpose: Specify the namespace for the parser class.
For example, if you specify: For example, if you specify:
@smallexample @smallexample
@@ -5150,7 +5150,7 @@ The parser namespace is @code{foo} and @code{yylex} is referenced as
@itemize @bullet @itemize @bullet
@item Language(s): C (deterministic parsers only) @item Language(s): C (deterministic parsers only)
@item Purpose: Requests a pull parser, a push parser, or both. @item Purpose: Request a pull parser, a push parser, or both.
@xref{Push Decl, ,A Push Parser}. @xref{Push Decl, ,A Push Parser}.
(The current push parsing interface is experimental and may evolve. (The current push parsing interface is experimental and may evolve.
More user feedback will help to stabilize it.) More user feedback will help to stabilize it.)
@@ -5302,8 +5302,8 @@ That is, it does not perform any extra reductions.
@itemize @bullet @itemize @bullet
@item Language(s): all @item Language(s): all
@item Purpose: Requests that Bison allow unreachable parser states to remain in @item Purpose: Request that Bison allow unreachable parser states to
the parser tables. remain in the parser tables.
Bison considers a state to be unreachable if there exists no sequence of Bison considers a state to be unreachable if there exists no sequence of
transitions from the start state to that state. transitions from the start state to that state.
A state can become unreachable during conflict resolution if Bison disables a A state can become unreachable during conflict resolution if Bison disables a
@@ -5351,7 +5351,7 @@ However, Bison does not compute which goto actions are useless.
@itemize @bullet @itemize @bullet
@item Language(s): all @item Language(s): all
@item Purpose: Specifies the type of parser tables within the @item Purpose: Specify the type of parser tables within the
@acronym{LR}(1) family. @acronym{LR}(1) family.
(This feature is experimental. (This feature is experimental.
More user feedback will help to stabilize it.) More user feedback will help to stabilize it.)
@@ -5378,6 +5378,10 @@ In this case, the use of @acronym{LALR} parser tables is guaranteed not
to alter the language accepted by the parser. to alter the language accepted by the parser.
@acronym{LALR} parser tables are the smallest parser tables Bison can @acronym{LALR} parser tables are the smallest parser tables Bison can
currently generate, so they may be preferable. currently generate, so they may be preferable.
Nevertheless, once you begin to resolve conflicts statically,
@acronym{GLR} begins to behave more like a deterministic parser, and so
@acronym{IELR} and canonical @acronym{LR} can be helpful to avoid
@acronym{LALR}'s mysterious behavior.
@item Occasionally during development, an especially malformed grammar @item Occasionally during development, an especially malformed grammar
with a major recurring flaw may severely impede the @acronym{IELR} or with a major recurring flaw may severely impede the @acronym{IELR} or
@@ -5590,7 +5594,7 @@ is not already defined, so that the debugging facilities are compiled.
C++ C++
@item Purpose: @item Purpose:
Requests variant-based semantic values. Request variant-based semantic values.
@xref{C++ Variants}. @xref{C++ Variants}.
@item Accepted Values: @item Accepted Values: