Info: (wisent) Conflicts

wisent: Conflicts

 
 2.4 Conflicts
 =============
 
 Normally, a grammar should produce an automaton where at each state the
 parser has only one action to do (Wisent Parsing).
 
    In certain cases, a grammar can produce an automaton where, at some
 states, there are more than one action possible.  Such a grammar is
 “ambiguous”, and generates “conflicts”.
 
    The parser can’t be driven by an automaton which isn’t completely
 “deterministic”, that is which contains conflicts.  It is necessary to
 resolve the conflicts to eliminate them.  Wisent resolves conflicts like
 Bison does.
 
    There are two sorts of conflicts:
 
 “shift/reduce conflicts”
      When either a shift or a reduction would be valid at the same
      state.
 
      Such conflicts are resolved by choosing to shift, unless otherwise
      directed by operator precedence declarations.  See 
      (bison)Shift/Reduce, in the Bison manual for more information.
 
 “reduce/reduce conflicts”
      That occurs if there are two or more rules that apply to the same
      sequence of input.  This usually indicates a serious error in the
      grammar.
 
      Such conflicts are resolved by choosing to use the rule that
      appears first in the grammar, but it is very risky to rely on this.
      Every reduce/reduce conflict must be studied and usually
      eliminated.  See (bison)Reduce/Reduce, in the Bison manual
      for more information.
wisent: Conflicts

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