@item Default Value: @code{false}
@end itemize
-@end table
@c parse.trace
+
+@item token.prefix
+@findex %define token.prefix
+
+@itemize
+@item Languages(s): all
+
+@item Purpose:
+Add a prefix to the token names when generating their definition in the
+target language. For instance
+
+@example
+%token FILE for ERROR
+%define token.prefix "TOK_"
+%%
+start: FILE for ERROR;
+@end example
+
+@noindent
+generates the definition of the symbols @code{TOK_FILE}, @code{TOK_for},
+and @code{TOK_ERROR} in the generated source files. In particular, the
+scanner must use these prefixed token names, while the grammar itself
+may still use the short names (as in the sample rule given above). The
+generated informational files (@file{*.output}, @file{*.xml},
+@file{*.dot}) are not modified by this prefix. See @ref{Calc++ Parser}
+and @ref{Calc++ Scanner}, for a complete example.
+
+@item Accepted Values:
+Any string. Should be a valid identifier prefix in the target language,
+in other words, it should typically be an identifier itself (sequence of
+letters, underscores, and ---not at the beginning--- digits).
+
+@item Default Value:
+empty
+@end itemize
+@c token.prefix
+
+@end table
@end deffn
-@c %define
+@c ---------------------------------------------------------- %define
@deffn {Directive} %defines
Write a header file containing macro definitions for the token type
@noindent
The token numbered as 0 corresponds to end of file; the following line
-allows for nicer error messages referring to ``end of file'' instead
-of ``$end''. Similarly user friendly named are provided for each
-symbol. Note that the tokens names are prefixed by @code{TOKEN_} to
-avoid name clashes.
+allows for nicer error messages referring to ``end of file'' instead of
+``$end''. Similarly user friendly names are provided for each symbol.
+To avoid name clashes in the generated files (@pxref{Calc++ Scanner}),
+prefix tokens with @code{TOK_} (@pxref{Decl Summary,, token.prefix}).
@comment file: calc++-parser.yy
@example
+%define token.prefix "TOK_"
%token END 0 "end of file"
%token ASSIGN ":="
%token <sval> IDENTIFIER "identifier"
%start unit;
unit: assignments exp @{ driver.result = $2; @};
-assignments: assignments assignment @{@}
- | /* Nothing. */ @{@};
+assignments:
+ assignments assignment @{@}
+| /* Nothing. */ @{@};
assignment:
- "identifier" ":=" exp
+ "identifier" ":=" exp
@{ driver.variables[*$1] = $3; delete $1; @};
%left '+' '-';
%left '*' '/';
-exp: exp '+' exp @{ $$ = $1 + $3; @}
- | exp '-' exp @{ $$ = $1 - $3; @}
- | exp '*' exp @{ $$ = $1 * $3; @}
- | exp '/' exp @{ $$ = $1 / $3; @}
- | '(' exp ')' @{ $$ = $2; @}
- | "identifier" @{ $$ = driver.variables[*$1]; delete $1; @}
- | "number" @{ $$ = $1; @};
+exp:
+ exp '+' exp @{ $$ = $1 + $3; @}
+| exp '-' exp @{ $$ = $1 - $3; @}
+| exp '*' exp @{ $$ = $1 * $3; @}
+| exp '/' exp @{ $$ = $1 / $3; @}
+| '(' exp ')' @{ $$ = $2; @}
+| "identifier" @{ $$ = driver.variables[*$1]; delete $1; @}
+| "number" @{ $$ = $1; @};
%%
@end example
# undef yywrap
# define yywrap() 1
-/* By default yylex returns int, we use token_type.
- Unfortunately yyterminate by default returns 0, which is
+/* By default yylex returns an int; we use token_type.
+ The default yyterminate implementation returns 0, which is
not of token_type. */
-#define yyterminate() return token::END
+#define yyterminate() return TOKEN(END)
%@}
@end example
@end example
@noindent
-The rules are simple, just note the use of the driver to report errors.
-It is convenient to use a typedef to shorten
-@code{yy::calcxx_parser::token::identifier} into
-@code{token::identifier} for instance.
+The rules are simple. The driver is used to report errors. It is
+convenient to use a macro to shorten
+@code{yy::calcxx_parser::token::TOK_@var{Name}} into
+@code{TOKEN(@var{Name})}; note the token prefix, @code{TOK_}.
@comment file: calc++-scanner.ll
@example
%@{
- typedef yy::calcxx_parser::token token;
+# define TOKEN(Name) \
+ yy::calcxx_parser::token::TOK_ ## Name
%@}
/* Convert ints to the actual type of tokens. */
[-+*/()] return yy::calcxx_parser::token_type (yytext[0]);
-":=" return token::ASSIGN;
+":=" return TOKEN(ASSIGN);
@{int@} @{
errno = 0;
long n = strtol (yytext, NULL, 10);
if (! (INT_MIN <= n && n <= INT_MAX && errno != ERANGE))
driver.error (*yylloc, "integer is out of range");
yylval->ival = n;
- return token::NUMBER;
+ return TOKEN(NUMBER);
+@}
+@{id@} @{
+ yylval->sval = new std::string (yytext);
+ return TOKEN(IDENTIFIER);
@}
-@{id@} yylval->sval = new std::string (yytext); return token::IDENTIFIER;
. driver.error (*yylloc, "invalid character");
%%
@end example
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