YACC grammar reduce/reduce conflict

Question

I have the following grammar for checking the validity of an XML file, the file starts with an element and then the root node.

program
    : terminal_node
      root
    ;
root
    : '<' ID attribute_list '>' node_list '<' ID '/''>'
    ;
node_list
    : node
    | node node_list
    ;
node
    : terminal_node
    : nonterminal_node
    ;   

terminal_node
    : '<' ID attribute_list '/''>'
    ;

nonterminal_node
    : '<' ID attribute_list '>' node_list '<' ID '/''>'
    ;
attribute_list
    : attribute
    | attribute attribute_list
    ;

attribute
    : ID ASSIGNOP '"' ID '"'
    | ID ASSIGNOP '"' NUM '"'
    ;

I am getting 1 reduce/reduce conflict, and I don't know how to find it. Any help would be appreciated.

"root" and "nonterminal_node" are exactly the same. – wildplasser Mar 10 '12 at 20:12 — wildplasser, Mar 10 '12 at 20:12

score 1 · Accepted Answer · answered Mar 10 '12 at 20:16

1

This looks a bit strange for an XML grammar. Are you sure you don't want empty node_lists or attribute_lists?

Anyway, try this:

node_list
    : node
    | node_list node /* list first, element second, this is the LALR way */
    ;
node
    : terminal_node
    | nonterminal_node /* note a typo in your code here */
    ;

answered Mar 10 '12 at 20:16

n. m. could be an AI

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it is a fist version just to make sure it works, yes I figured it out it should be `node_list node` thanks for the answer though. – mihajlv Mar 10 '12 at 20:22

YACC grammar reduce/reduce conflict

1 Answers1