Re: Getting verbose output from the parser

["Greg Borota" <depaulcti@xxxxxxxxx>]

I am not an expert in the subject but anyway I think you would better
let the lexer "decide" what's a float literal (that's it, define it in
the Helpers/Tokens section).

You can find already tested ways of defining float_literals on SableCC
site, grammars section
http://sablecc.org/grammars.html
http://sablecc.org/grammars/ISOC.grammar.html
http://sablecc.org/grammars/j14.sablecc.html

Please not that many of those grammars have an interpreter/parser,etc.
associated that can be obtained by clicking on the Download link (did
not notice this at first):
http://sourceforge.net/project/showfiles.php?group_id=5704
etc.

Greg

Helpers
floating_constant =
		decimal_floating_constant |
		hex_floating_constant;

Tokens




On 6/10/06, Stephen Torri <storri@xxxxxxxxx> wrote:
> Is there a way to get more verbose output from the parser than just a
> ParserException? I need to develop a parser which can recognize the C++
> programming language. For starters I am working on the recognizing two
> basic types, floats and integers. The integers are being recognized
> correctly but the floats are stopping at the second character with an
> exception.
>
> Why will this grammar not recognize "2.52e+8" or "7E5"?
>
> Stephen
>
> --------------------
>
> Package CPP;
>
> Helpers
>
>
>     blank = ' ';
> //    char = [['a'..'z']+['A'..'Z']];
>     digit = ['0'..'9'];
>     eol = 10 | 13;
>     hexidecimal_digit= ['a'..'f'] | ['A'..'F'] | ['0'..'9'];
>     non_zero_digit = ['1'..'9'];
>     octal_digit = ['0'..'7'];
>     sign = '+' | '-';
>
> Tokens
>
>     // ******************************
>     //        Characters
>     // ******************************
>     tk_blank = 9 | 10 | 13 | blank;
>     tk_float_suffix = 'f' | 'F';
>     tk_long_suffix = 'l' | 'L';
>     tk_exponent = 'e' | 'E';
>     tk_sign = sign;
>
>     // Basic numbers
>     tk_decimal_literal = non_zero_digit digit*;
>     tk_digit = digit;
>     tk_digit_sequence = digit+;
>     tk_hexidecimal_literal = ( '0x' | '0X' ) hexidecimal_digit*;
>
>     tk_octal_literal = '0' octal_digit*;
>     tk_unsigned_suffix = 'u' | 'U';
>
>     // Basic characters
>     tk_left_paren = '(';
>     tk_period = '.';
>     tk_right_paren = ')';
>
> Ignored Tokens
>
>     tk_blank;
>
> Productions
>
> //   literal ::= integer-literal |
> //               character-literal |
> //               floating-literal |
> //               string-literal |
> //               boolean-literal |
> //               null-literal    // __null
>
>   literal =
>         {float} floating_literal |
>         {int} integer_literal;
>
>         //string_literal |
>         //boolean_literal |
>         //null_literal;
>
>   // Floating point numbers
>   floating_literal =
>         {frac} fractional_constant
>           exponent_part?
>           float_suffix? |
>         {seq} tk_digit+
>           exponent_part
>           float_suffix?;
>
>   fractional_constant =
>         {fraction} [num]:tk_digit_sequence? tk_period
> [exp]:tk_digit_sequence |
>         {whole} tk_digit_sequence tk_period;
>
>   float_suffix = {f_char} tk_float_suffix |
>         {l_char} tk_long_suffix;
>
>   exponent_part = tk_exponent tk_sign? tk_digit_sequence;
>
>   // Integer numbers
>   integer_literal =
>         {dec} tk_decimal_literal integer_suffix? |
>         {oct} tk_octal_literal integer_suffix? |
>         {hex} tk_hexidecimal_literal integer_suffix?;
>
>   integer_suffix =
>         {ul} tk_unsigned_suffix tk_long_suffix? |
>         {lu} tk_long_suffix tk_unsigned_suffix?;
>
>
>
>
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