Re: Bison can not create LR table

[Paul Hilfinger]

With a few additions, I get the same result you did, but this grammar,
while it is LR(2), is not LR(1) or LALR(1).  Suppose that the input
contains

     MOV @ R 3 , #

At the crucial point, we'll have

   MOV @ R ireg

on the stack (right end is top) and "," as the lookahead.  This is not
enough data to decide whether to reduce to ireg_MOVE_INDIRECT_DIRECT,
ireg_MOVE_INDIRECT_A, or ireg_MOVE_INDIRECT_DATA.

Paul Hilfinger



    %term const_num

    %%

    inst: MOVE_INDIRECT_DIRECT | MOVE_INDIRECT | MOVE_INDIRECT_DATA ;

    MOVE_INDIRECT_DIRECT: "MOV" "@" "R" ireg_MOVE_INDIRECT_DIRECT ","
    dir_MOVE_INDIRECT_DIRECT
                          {
                          ...
                          };
    MOVE_INDIRECT: "MOV" "@" "R" ireg_MOVE_INDIRECT_A "," "A"
                    {
                    ...
                    };
    MOVE_INDIRECT_DATA: "MOV" "@" "R" ireg_MOVE_INDIRECT_DATA "," "#"
    data_MOVE_INDIRECT_DATA
                    {
                    ...
                    };

    ireg_MOVE_INDIRECT_DIRECT: ireg
                                {
                                   $$ = $1;
                                };
    ireg_MOVE_INDIRECT_A: ireg
                                {
                                   $$ = $1;
                                };
    ireg_MOVE_INDIRECT_DATA: ireg
                                {
                                   $$ = $1;
                                };

    dir_MOVE_INDIRECT_DIRECT: byte
                             {
                                $$ = $1;
                             };

    data_MOVE_INDIRECT_DATA: byte
                             {
                                $$ = $1;
                             };

    ireg: const_num //decadical value from lex
        {
        ...
        };

    byte: const_num //decadical value from lex
        {
        ...
        };

    %%