void initialize_contradiction_tactic() {
register_tac(name{"tactic", "contradiction"},
[](type_checker &, elaborate_fn const &, expr const &, pos_info_provider const *) {
list<name> empty;
return then(orelse(intros_tactic(empty), id_tactic()), contradiction_tactic());
});
}
// Set *value to the value of the cell at (r,c), unless there's an
// error; in which case return either the error's plaint or
// derived_plaint -- the latter to keep from propagating a plaint
// between cells -- we want to propagate only the fact of the error,
// not the plaint itself.
static const char *get_value (Value *value, unsigned r, unsigned c,
const char *derived_plaint) {
if (rows <= r || cols <= c)
return "Cell out of range";
Cell *cell = &cells[r][c];
if (cell->plaint == unknown)
update (r, c);
if (cell->plaint == calculating)
return calculating;
if (cell->plaint)
return orelse (derived_plaint, cell->plaint);
*value = cell->value;
return NULL;
}
SET_MSG (Msg_Text, Msg_Temp, ")");
fatal(4012); /* missing right paren */
}
return(val);
}
/************************************************************************/
/* constexpr ::= orelse [ '?' orelse ':' orelse ]; */
/************************************************************************/
long constexpr(void)
{
REG long val;
REG long val1;
long val2;
val = orelse();
if( nextis(L_QUEST) ) {
val1 = orelse();
if( nextis(L_COLON) )
val2 = orelse();
return(val ? val1 : val2);
}
return(val);
}
/************************************************************************/
/* orelse ::= andif [ '||' andif ]* ; */
/************************************************************************/
long orelse(void)
{
