Added right-to-left rules

src/params/smt_params.cpp

@@ -54,6 +54,7 @@ void smt_params::updt_local_params(params_ref const & _p) {
     m_logic = _p.get_sym("logic", m_logic);
     m_string_solver = p.string_solver();
     m_nseq_max_depth = p.nseq_max_depth();
+    m_nseq_parikh = p.nseq_parikh();
     m_up_persist_clauses = p.up_persist_clauses();
     validate_string_solver(m_string_solver);
     if (_p.get_bool("arith.greatest_error_pivot", false))

src/params/smt_params.h

@@ -249,6 +249,7 @@ struct smt_params : public preprocessor_params,
     // -----------------------------------
     symbol m_string_solver;
     unsigned m_nseq_max_depth = 0;
+    bool m_nseq_parikh = true;
 
     smt_params(params_ref const & p = params_ref()):
         m_string_solver(symbol("auto")){

src/params/smt_params_helper.pyg

@@ -124,6 +124,7 @@ def_module_params(module_name='smt',
                           ('theory_case_split', BOOL, False, 'Allow the context to use heuristics involving theory case splits, which are a set of literals of which exactly one can be assigned True. If this option is false, the context will generate extra axioms to enforce this instead.'),
                           ('string_solver', SYMBOL, 'seq', 'solver for string/sequence theories. options are: \'z3str3\' (specialized string solver), \'seq\' (sequence solver), \'auto\' (use static features to choose best solver), \'empty\' (a no-op solver that forces an answer unknown if strings were used), \'none\' (no solver), \'nseq\' (Nielsen-based string solver)'),
                           ('nseq.max_depth', UINT, 0, 'maximum Nielsen search depth for theory_nseq (0 = unlimited)'),
+                          ('nseq.parikh', BOOL, True, 'enable Parikh image checks in nseq solver'),
                           ('core.validate', BOOL, False, '[internal] validate unsat core produced by SMT context. This option is intended for debugging'),
                           ('seq.split_w_len', BOOL, True, 'enable splitting guided by length constraints'),
                           ('seq.validate', BOOL, False, 'enable self-validation of theory axioms created by seq theory'),