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doc: minor fixes

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* doc/bison.texi: Simplify wording.
Fix Texinfo error.
(Complete Symbols): Handle the token EOF.
(Calc++ Parser): In the modern C++ world, prefer assignment to swap.
(Strings are Destroyed): Prefer an explicit 'continue' to a comment.
This commit is contained in:
Akim Demaille
2018-10-25 07:03:15 +02:00
parent 849d91bc02
commit 18743948b5
1 changed files with 13 additions and 10 deletions
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23
doc/bison.texi
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@@ -10848,7 +10848,7 @@ same rules as with regular C parsers (@pxref{Invocation}).
@item location.hh
Generated when both @code{%defines} and @code{%locations} are enabled, this
file contains the definition of the classes @code{position} and
@code{location}, used for location tracking. This file is not generated if
@code{location}, used for location tracking. It is not generated if
@samp{%define api.location.file none} is specified, or if user defined
locations are used. @xref{C++ Location Values}.
@@ -11406,7 +11406,7 @@ api.token.constructor}, the parser defines the type @code{symbol_type}, and
expects @code{yylex} to have the following prototype.
@deftypefun {parser::symbol_type} yylex ()
@deftypefunx {parser::symbol_type} yylex (var{type1} @var{arg1}, ...)
@deftypefunx {parser::symbol_type} yylex (@var{type1} @var{arg1}, ...)
Return a @emph{complete} symbol, aggregating its type (i.e., the traditional
value returned by @code{yylex}), its semantic value, and possibly its
location. Invocations of @samp{%lex-param @{@var{type1} @var{arg1}@}} yield
@@ -11432,6 +11432,7 @@ For instance, given the following declarations:
%token <std::string> IDENTIFIER;
%token <int> INTEGER;
%token COLON;
%token EOF 0;
@end example
@noindent
@@ -11441,20 +11442,22 @@ Bison generates:
symbol_type make_IDENTIFIER (const std::string&, const location_type&);
symbol_type make_INTEGER (const int&, const location_type&);
symbol_type make_COLON (const location_type&);
symbol_type make_EOF (const location_type&);
@end example
@noindent
which should be used in a Lex-scanner as follows.
which should be used in a Flex-scanner as follows.
@example
[0-9]+ return yy::parser::make_INTEGER (text_to_int (yytext), loc);
[a-z]+ return yy::parser::make_IDENTIFIER (yytext, loc);
[0-9]+ return yy::parser::make_INTEGER (text_to_int (yytext), loc);
":" return yy::parser::make_COLON (loc);
<<EOF>> return yy::parser::make_EOF (loc);
@end example
Tokens that do not have an identifier are not accessible: you cannot simply
use characters such as @code{':'}, they must be declared with @code{%token}.
use characters such as @code{':'}, they must be declared with @code{%token},
including the end-of-file token.
@node A Complete C++ Example
@subsection A Complete C++ Example
@@ -11523,7 +11526,7 @@ C++ parser expects it to be declared. We can factor both as follows.
@comment file: calc++/driver.hh
@example
// Tell Flex the lexer's prototype ...
// Give Flex the prototype of yylex we want ...
# define YY_DECL \
yy::parser::symbol_type yylex (driver& drv)
// ... and declare it for the parser's sake.
@@ -11779,7 +11782,7 @@ exp:
| exp "-" exp @{ $$ = $1 - $3; @}
| exp "*" exp @{ $$ = $1 * $3; @}
| exp "/" exp @{ $$ = $1 / $3; @}
| "(" exp ")" @{ std::swap ($$, $2); @}
| "(" exp ")" @{ $$ = $2; @}
%%
@end example
@@ -11915,7 +11918,7 @@ the blanks preceding tokens. Comments would be treated equally.
%@}
@end group
@{blank@}+ loc.step ();
[\n]+ loc.lines (yyleng); loc.step ();
\n+ loc.lines (yyleng); loc.step ();
@end example
@noindent
@@ -12857,7 +12860,7 @@ char *yylval = NULL;
@group
%%
.* yylval = yytext; return 1;
\n /* IGNORE */
\n continue;
%%
@end group
@group