Evening All,
I’m writing a Bison parser and, being relatively new to this, I’m confused
about how to tie my scanner (for flex) together with my bison (version 3.04 so
I can use C++) parser. For example, in my scanner.l file I have the following:
#define INT_TOKEN(tok, val) YIELD_TOKEN(tok, val, int)
#define NUM_TOKEN(tok) YIELD_TOKEN(tok, YY_NUM, double)
#define STR_TOKEN(tok) YIELD_TOKEN(tok, YY_TXT, std::string)
#define SEP_TOKEN(tok) return yytext[0];
#define LITERAL return yytext[0];
#define YY_USER_ACTION yyloc->columns(yyleng);
%}
%%
/* code to be executed at every yylex() call */
%{
yyloc->step();
%}
sig STR_TOKEN(SIG)
fact STR_TOKEN(FACT)
hint STR_TOKEN(HINT)
[[:digit:]]+ NUM_TOKEN(NUM)
[[:alpha:]][[:alnum:]_]* STR_TOKEN(NAME)
+ INT_TOKEN(SIGN, ast::SIGN_PLUS)
- INT_TOKEN(SIGN, ast::SIGN_MINUS)
* INT_TOKEN(SIGN, ast::SIGN_MULTIPLY)
/ INT_TOKEN(SIGN, ast::SIGN_DIVISION)
= INT_TOKEN(SIGN, ast::EQUAL)
{ INT_TOKEN(SIGN, ast::LBRACE)
( INT_TOKEN(SIGN, ast::LPAREN)
: INT_TOKEN(SIGN, ast::COLON)
} INT_TOKEN(SIGN, ast::RBRACE)
) INT_TOKEN(SIGN, ast::RPAREN)
Where my ast::XXX are enum’s that I’ve declared in my C++ header file…
But then I naively tried to used a rule in my parser.y file such as:
object: SIG NAME RBRACE list LBRACE { $$ = new Object( $2, $4 ); }
;
But then I get the error in transpiling:
$ make
/usr/local/bin/bison parser.y
parser.y:115.30-35: error: symbol LBRACE is used, but is not defined as a token
and has no rules
object: SIG NAME RBRACE list LBRACE { $$ = new Object( $2, $4 ); }
And so I’m a little confused, I could of course declare LBRACE and so forth as
tokens in the parser.y, like so (these are all the tokens in my parser.y file):
%token END 0 "end of file"
%token FACT "fact"
%token SIG "sig"
%token HINT “hint”
%token <std::string> NAME
%token <double> NUM
%token <int> SIGN
REL
But then, how does that tie in with the flex scanner?? Where should I be tying
these two pieces together? Shouldn’t they use the same enum value (the
integer)?
Thanks for any help and advice you can give.
_______________________________________________
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