Reputation: 63
I've got a short question regarding my grammar in bison. The files compile, but it does not give the result I actually wanted. ;-)
My example file that I want to parse:
L1: ldh [23]
The lexer file looks like this:
...
digit [0-9]
digit_s [1-9]
digit_n [0]
hex [a-fA-F0-9]
hex_x [x]
number_dec {digit_n}|{digit_s}{digit}*
number_hex {digit_n}{hex_x}{hex}+
label_s [a-zA-Z]
label_me [a-zA-Z0-9_]+
label {label_s}{label_me}+
%%
"ldb" { return OP_LDB; }
"ldh" { return OP_LDH; }
...
{number_hex} { yylval.number = strtoul(yytext, NULL, 16);
return number_hex; }
{number_dec} { yylval.number = strtoul(yytext, NULL, 10);
return number_dec; }
{label} { yylval.label = xstrdup(yytext);
return label; }
The bison file like this:
...
%}
%union {
int number;
char *label;
}
%token OP_LDB OP_LDH ...
%token number_hex number_dec label
%type <number> number_hex number_dec number do_ldb
%type <label> label do_label
%%
prog
: {}
| prog line { }
;
line
: instr { }
| labeled_instr { }
;
labeled_instr
: do_label instr { }
;
instr
: do_ldb { }
| do_ldh { }
...
;
number
: number_dec { $$ = $1; }
| number_hex { $$ = $1; }
;
do_label
: label ':' { info("got:%s\n", $1); }
;
do_ldb
: OP_LDB '[' 'x' '+' number ']' { info("got:%d\n", $5); }
| OP_LDB '[' number ']' { info("got:%d\n", $3); }
;
Now my program tells my the following:
Syntax error at line 1: ldh! syntax error, unexpected OP_LDH, expecting ':'!
Do you have any idea what I did wrong?
Big thanks!
Upvotes: 4
Views: 360
Reputation: 126526
You're probably missing the rule
":" { return ':'; }
or something equivalent in your lexer
If you are using flex
, you probably want to give it the --nodefault
option to ensure that you don't miss some input tokens. Alternately, you can stick %option nodefault
in the first section.
Upvotes: 2