Future/bison
1
0
Fork 0
mirror of https://git.savannah.gnu.org/git/bison.git synced 2026-03-09 20:33:03 +00:00
Code Issues Packages Projects Releases Wiki Activity

examples: calc++: remove prefixes

Browse Source 
This example uses the calcxx_ prefix for each class.  That's uselessly
heavy.

* doc/bison.texi (A Complete C++ Example): Simplify the class names.
Since now 'driver' denotes the class, use 'drv' for the values.
Formatting changes.
This commit is contained in:
Akim Demaille
2018-08-23 18:50:46 +02:00
parent e504c843c1
commit 82fa282a1b
1 changed files with 63 additions and 73 deletions
Download Patch File Download Diff File Expand all files Collapse all files

136
doc/bison.texi
View File

@@ -10854,14 +10854,13 @@ files, reused by other parsers as follows:
@c debug_stream.
@c - Reporting errors
The output files @file{@var{output}.hh} and @file{@var{output}.cc}
declare and define the parser class in the namespace @code{yy}. The
class name defaults to @code{parser}, but may be changed using
@samp{%define parser_class_name @{@var{name}@}}. The interface of
this class is detailed below. It can be extended using the
@code{%parse-param} feature: its semantics is slightly changed since
it describes an additional member of the parser class, and an
additional argument for its constructor.
The output files @file{@var{output}.hh} and @file{@var{output}.cc} declare
and define the parser class in the namespace @code{yy}. The class name
defaults to @code{parser}, but may be changed using @samp{%define
parser_class_name @{@var{name}@}}. The interface of this class is detailed
below. It can be extended using the @code{%parse-param} feature: its
semantics is slightly changed since it describes an additional member of the
parser class, and an additional argument for its constructor.
@defcv {Type} {parser} {semantic_type}
@defcvx {Type} {parser} {location_type}
@@ -11105,17 +11104,16 @@ seven * seven
@c - A place to store error messages
@c - A place for the result
To support a pure interface with the parser (and the scanner) the
technique of the ``parsing context'' is convenient: a structure
containing all the data to exchange. Since, in addition to simply
launch the parsing, there are several auxiliary tasks to execute (open
the file for parsing, instantiate the parser etc.), we recommend
transforming the simple parsing context structure into a fully blown
@dfn{parsing driver} class.
To support a pure interface with the parser (and the scanner) the technique
of the ``parsing context'' is convenient: a structure containing all the
data to exchange. Since, in addition to simply launch the parsing, there
are several auxiliary tasks to execute (open the file for scanning,
instantiate the parser etc.), we recommend transforming the simple parsing
context structure into a fully blown @dfn{parsing driver} class.
The declaration of this driver class, in @file{driver.hh}, is as follows. The
first part includes the CPP guard and imports the required standard library
components, and the declaration of the parser class.
The declaration of this driver class, in @file{driver.hh}, is as follows.
The first part includes the CPP guard and imports the required standard
library components, and the declaration of the parser class.
@comment file: calc++/driver.hh
@example
@@ -11128,32 +11126,29 @@ components, and the declaration of the parser class.
@noindent
Then comes the declaration of the scanning function. Flex expects
the signature of @code{yylex} to be defined in the macro
@code{YY_DECL}, and the C++ parser expects it to be declared. We can
factor both as follows.
Then comes the declaration of the scanning function. Flex expects the
signature of @code{yylex} to be defined in the macro @code{YY_DECL}, and the
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 ...
# define YY_DECL \
yy::calcxx_parser::symbol_type yylex (calcxx_driver& driver)
yy::parser::symbol_type yylex (driver& drv)
// ... and declare it for the parser's sake.
YY_DECL;
@end example
@noindent
The @code{calcxx_driver} class is then declared with its most obvious
members.
The @code{driver} class is then declared with its most obvious members.
@comment file: calc++/driver.hh
@example
// Conducting the whole scanning and parsing of Calc++.
class calcxx_driver
class driver
@{
public:
calcxx_driver ();
virtual ~calcxx_driver ();
driver ();
std::map<std::string, int> variables;
@@ -11212,37 +11207,35 @@ messages and set error state.
#include "driver.hh"
#include "parser.hh"
calcxx_driver::calcxx_driver ()
driver::driver ()
: trace_scanning (false), trace_parsing (false)
@{
variables["one"] = 1;
variables["two"] = 2;
@}
calcxx_driver::~calcxx_driver ()
@{
@}
@group
int
calcxx_driver::parse (const std::string &f)
driver::parse (const std::string &f)
@{
file = f;
scan_begin ();
yy::calcxx_parser parser (*this);
yy::parser parser (*this);
parser.set_debug_level (trace_parsing);
int res = parser.parse ();
scan_end ();
return res;
@}
@end group
void
calcxx_driver::error (const yy::location& l, const std::string& m)
driver::error (const yy::location& l, const std::string& m)
@{
std::cerr << l << ": " << m << '\n';
@}
void
calcxx_driver::error (const std::string& m)
driver::error (const std::string& m)
@{
std::cerr << m << '\n';
@}
@@ -11252,16 +11245,15 @@ calcxx_driver::error (const std::string& m)
@subsubsection Calc++ Parser
The grammar file @file{parser.yy} starts by asking for the C++ deterministic
parser skeleton, the creation of the parser header file, and specifies the
name of the parser class. Because the C++ skeleton changed several times,
it is safer to require the version you designed the grammar for.
parser skeleton, the creation of the parser header file. Because the C++
skeleton changed several times, it is safer to require the version you
designed the grammar for.
@comment file: calc++/parser.yy
@example
%skeleton "lalr1.cc" /* -*- C++ -*- */
%require "@value{VERSION}"
%defines
%define parser_class_name @{calcxx_parser@}
@end example
@noindent
@@ -11294,7 +11286,7 @@ forward declaration of the driver. @xref{%code Summary}.
%code requires
@{
# include <string>
class calcxx_driver;
class driver;
@}
@end example
@@ -11306,7 +11298,7 @@ global variables.
@comment file: calc++/parser.yy
@example
// The parsing context.
%param @{ calcxx_driver& driver @}
%param @{ driver& drv @}
@end example
@noindent
@@ -11321,7 +11313,7 @@ propagated.
%initial-action
@{
// Initialize the initial location.
@@$.begin.filename = @@$.end.filename = &driver.file;
@@$.begin.filename = @@$.end.filename = &drv.file;
@};
@end example
@@ -11338,8 +11330,8 @@ messages. However, verbose error messages can contain incorrect information
@noindent
@findex %code
The code between @samp{%code @{} and @samp{@}} is output in the
@file{*.cc} file; it needs detailed knowledge about the driver.
The code between @samp{%code @{} and @samp{@}} is output in the @file{*.cc}
file; it needs detailed knowledge about the driver.
@comment file: calc++/parser.yy
@example
@@ -11403,14 +11395,14 @@ Location Tracking Calculator - @code{ltcalc}}).
@example
%%
%start unit;
unit: assignments exp @{ driver.result = $2; @};
unit: assignments exp @{ drv.result = $2; @};
assignments:
%empty @{@}
| assignments assignment @{@};
assignment:
"identifier" ":=" exp @{ driver.variables[$1] = $3; @};
"identifier" ":=" exp @{ drv.variables[$1] = $3; @};
%left "+" "-";
%left "*" "/";
@@ -11420,22 +11412,20 @@ exp:
| exp "*" exp @{ $$ = $1 * $3; @}
| exp "/" exp @{ $$ = $1 / $3; @}
| "(" exp ")" @{ std::swap ($$, $2); @}
| "identifier" @{ $$ = driver.variables[$1]; @}
| "identifier" @{ $$ = drv.variables[$1]; @}
| "number" @{ std::swap ($$, $1); @};
%%
@end example
@noindent
Finally the @code{error} member function registers the errors to the
driver.
Finally the @code{error} member function registers the errors to the driver.
@comment file: calc++/parser.yy
@example
void
yy::calcxx_parser::error (const location_type& l,
const std::string& m)
yy::parser::error (const location_type& l, const std::string& m)
@{
driver.error (l, m);
drv.error (l, m);
@}
@end example
@@ -11527,26 +11517,26 @@ The rules are simple. The driver is used to report errors.
@comment file: calc++/scanner.ll
@example
"-" return yy::calcxx_parser::make_MINUS (loc);
"+" return yy::calcxx_parser::make_PLUS (loc);
"*" return yy::calcxx_parser::make_STAR (loc);
"/" return yy::calcxx_parser::make_SLASH (loc);
"(" return yy::calcxx_parser::make_LPAREN (loc);
")" return yy::calcxx_parser::make_RPAREN (loc);
":=" return yy::calcxx_parser::make_ASSIGN (loc);
"-" return yy::parser::make_MINUS (loc);
"+" return yy::parser::make_PLUS (loc);
"*" return yy::parser::make_STAR (loc);
"/" return yy::parser::make_SLASH (loc);
"(" return yy::parser::make_LPAREN (loc);
")" return yy::parser::make_RPAREN (loc);
":=" return yy::parser::make_ASSIGN (loc);
@group
@{int@} @{
errno = 0;
long n = strtol (yytext, NULL, 10);
if (! (INT_MIN <= n && n <= INT_MAX && errno != ERANGE))
driver.error (loc, "integer is out of range");
return yy::calcxx_parser::make_NUMBER (n, loc);
drv.error (loc, "integer is out of range");
return yy::parser::make_NUMBER (n, loc);
@}
@end group
@{id@} return yy::calcxx_parser::make_IDENTIFIER (yytext, loc);
. driver.error (loc, "invalid character");
<<EOF>> return yy::calcxx_parser::make_END (loc);
@{id@} return yy::parser::make_IDENTIFIER (yytext, loc);
. drv.error (loc, "invalid character");
<<EOF>> return yy::parser::make_END (loc);
%%
@end example
@@ -11558,7 +11548,7 @@ on the scanner's data, it is simpler to implement them in this file.
@example
@group
void
calcxx_driver::scan_begin ()
driver::scan_begin ()
@{
yy_flex_debug = trace_scanning;
if (file.empty () || file == "-")
@@ -11573,7 +11563,7 @@ calcxx_driver::scan_begin ()
@group
void
calcxx_driver::scan_end ()
driver::scan_end ()
@{
fclose (yyin);
@}
@@ -11595,14 +11585,14 @@ int
main (int argc, char *argv[])
@{
int res = 0;
calcxx_driver driver;
driver drv;
for (int i = 1; i < argc; ++i)
if (argv[i] == std::string ("-p"))
driver.trace_parsing = true;
drv.trace_parsing = true;
else if (argv[i] == std::string ("-s"))
driver.trace_scanning = true;
else if (!driver.parse (argv[i]))
std::cout << driver.result << '\n';
drv.trace_scanning = true;
else if (!drv.parse (argv[i]))
std::cout << drv.result << '\n';
else
res = 1;
return res;