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doc: formatting changes

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* doc/bison.texi: here.
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Akim Demaille
2019-12-07 14:41:50 +01:00
parent 472531dc72
commit 5e71eef267
1 changed files with 42 additions and 45 deletions
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doc/bison.texi
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@@ -367,9 +367,9 @@ Debugging Your Parser
Tracing Your Parser
* Enabling Traces:: Activating run-time trace support
* Mfcalc Traces:: Extending @code{mfcalc} to support traces
* The YYPRINT Macro:: Obsolete interface for semantic value reports
* Enabling Traces:: Activating run-time trace support
* Mfcalc Traces:: Extending @code{mfcalc} to support traces
* The YYPRINT Macro:: Obsolete interface for semantic value reports
Invoking Bison
@@ -2897,25 +2897,25 @@ of line.
@cindex Prologue
@cindex declarations
The @var{Prologue} section contains macro definitions and declarations
of functions and variables that are used in the actions in the grammar
rules. These are copied to the beginning of the parser implementation
file so that they precede the definition of @code{yyparse}. You can
use @samp{#include} to get the declarations from a header file. If
you don't need any C declarations, you may omit the @samp{%@{} and
@samp{%@}} delimiters that bracket this section.
The @var{Prologue} section contains macro definitions and declarations of
functions and variables that are used in the actions in the grammar rules.
These are copied to the beginning of the parser implementation file so that
they precede the definition of @code{yyparse}. You can use @samp{#include}
to get the declarations from a header file. If you don't need any C
declarations, you may omit the @samp{%@{} and @samp{%@}} delimiters that
bracket this section.
The @var{Prologue} section is terminated by the first occurrence
of @samp{%@}} that is outside a comment, a string literal, or a
character constant.
The @var{Prologue} section is terminated by the first occurrence of
@samp{%@}} that is outside a comment, a string literal, or a character
constant.
You may have more than one @var{Prologue} section, intermixed with the
@var{Bison declarations}. This allows you to have C and Bison
declarations that refer to each other. For example, the @code{%union}
declaration may use types defined in a header file, and you may wish to
prototype functions that take arguments of type @code{YYSTYPE}. This
can be done with two @var{Prologue} blocks, one before and one after the
@code{%union} declaration.
@var{Bison declarations}. This allows you to have C and Bison declarations
that refer to each other. For example, the @code{%union} declaration may
use types defined in a header file, and you may wish to prototype functions
that take arguments of type @code{YYSTYPE}. This can be done with two
@var{Prologue} blocks, one before and one after the @code{%union}
declaration.
@example
@group
@@ -2943,12 +2943,11 @@ can be done with two @var{Prologue} blocks, one before and one after the
@dots{}
@end example
When in doubt, it is usually safer to put prologue code before all
Bison declarations, rather than after. For example, any definitions
of feature test macros like @code{_GNU_SOURCE} or
@code{_POSIX_C_SOURCE} should appear before all Bison declarations, as
feature test macros can affect the behavior of Bison-generated
@code{#include} directives.
When in doubt, it is usually safer to put prologue code before all Bison
declarations, rather than after. For example, any definitions of feature
test macros like @code{_GNU_SOURCE} or @code{_POSIX_C_SOURCE} should appear
before all Bison declarations, as feature test macros can affect the
behavior of Bison-generated @code{#include} directives.
@node Prologue Alternatives
@subsection Prologue Alternatives
@@ -2960,12 +2959,11 @@ feature test macros can affect the behavior of Bison-generated
@findex %code top
The functionality of @var{Prologue} sections can often be subtle and
inflexible. As an alternative, Bison provides a @code{%code}
directive with an explicit qualifier field, which identifies the
purpose of the code and thus the location(s) where Bison should
generate it. For C/C++, the qualifier can be omitted for the default
location, or it can be one of @code{requires}, @code{provides},
@code{top}. @xref{%code Summary}.
inflexible. As an alternative, Bison provides a @code{%code} directive with
an explicit qualifier field, which identifies the purpose of the code and
thus the location(s) where Bison should generate it. For C/C++, the
qualifier can be omitted for the default location, or it can be one of
@code{requires}, @code{provides}, @code{top}. @xref{%code Summary}.
Look again at the example of the previous section:
@@ -3060,21 +3058,20 @@ the same time:
@end example
@noindent
In this way, @code{%code top} and the unqualified @code{%code} achieve the same
functionality as the two kinds of @var{Prologue} sections, but it's always
explicit which kind you intend.
Moreover, both kinds are always available even in the absence of @code{%union}.
In this way, @code{%code top} and the unqualified @code{%code} achieve the
same functionality as the two kinds of @var{Prologue} sections, but it's
always explicit which kind you intend. Moreover, both kinds are always
available even in the absence of @code{%union}.
The @code{%code top} block above logically contains two parts. The
first two lines before the warning need to appear near the top of the
parser implementation file. The first line after the warning is
required by @code{YYSTYPE} and thus also needs to appear in the parser
implementation file. However, if you've instructed Bison to generate
a parser header file (@pxref{Decl Summary, ,%defines}), you probably
want that line to appear before the @code{YYSTYPE} definition in that
header file as well. The @code{YYLTYPE} definition should also appear
in the parser header file to override the default @code{YYLTYPE}
definition there.
The @code{%code top} block above logically contains two parts. The first
two lines before the warning need to appear near the top of the parser
implementation file. The first line after the warning is required by
@code{YYSTYPE} and thus also needs to appear in the parser implementation
file. However, if you've instructed Bison to generate a parser header file
(@pxref{Decl Summary, ,%defines}), you probably want that line to appear
before the @code{YYSTYPE} definition in that header file as well. The
@code{YYLTYPE} definition should also appear in the parser header file to
override the default @code{YYLTYPE} definition there.
In other words, in the @code{%code top} block above, all but the first two
lines are dependency code required by the @code{YYSTYPE} and @code{YYLTYPE}