yacc - Types of conflicts in Bison -

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%token<val>num  %left '+' '-'

example shift/reduce conflict:

expr:num {$$=$1};      |expr '+' expr;{};      |expr '-' expr;{};

i want recognize reduce/reduce conflict. occurs when 2 or more rules apply same sequence of input (token)

for example:

prod: proda|prodb      proda :'x'      prodb : 'x'

could give ideas how recognise reduce/reduce conflict easily?

easiest way create y.output file.

use command yacc -v parser_name.y. create output how yacc works. find state yacc says conflict is, , important understand point sign . in file means.

if output file says this:

4 |expr. '+' expr;{};

point sign after expression saying you: "i've read expr , on input have '+'.

reduce-reduce conflicts appear when have situation this:

non_terminal1: expr. non_terminal2: expr.

in situation, have expr. @ end of rule yacc doesn't know reduce , reduce-reduce conflict.


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