Expression Expression::simplify() const {
Expression postfactor = *this;
Expression prefactor = postfactor.ScalarFactor();
if (prefactor != Expression(1)) {
return prefactor * postfactor.simplify();
}
if (name == "*" && arg2->name == "*") {
if (arg2->arg1->kindIs("constant"))
return (*arg2->arg1 * *arg1 * *arg2->arg2).simplify();
if (arg2->arg2->kindIs("constant"))
return (*arg2->arg2 * *arg1 * *arg2->arg1).simplify();
return (*arg1 * *arg2->arg1 * *arg2->arg2).simplify();
}
if (kindIs("unary") && name == "-") {
Expression minusthis = arg1->simplify();
if (minusthis.kindIs("*/") && minusthis.arg1->kindIs("constant")) {
minusthis.arg1 = new Expression(-minusthis.arg1->value);
return minusthis;
}
if (minusthis.kindIs("*/") && minusthis.arg1->kindIs("*/") && minusthis.arg1->arg1->kindIs("constant")) {
minusthis.arg1->arg1 = new Expression(-minusthis.arg1->arg1->value);
return minusthis;
}
return -minusthis;
}
Expression out;
out.name = name;
out.type = type;
out.kind = kind;
out.alias = alias;
if (arg1) out.arg1 = new Expression(arg1->simplify());
if (arg2) out.arg2 = new Expression(arg2->simplify());
if (arg3) out.arg3 = new Expression(arg3->simplify());
return *this;
}
Expression Expression::ScalarFactor() {
if (kindIs("constant")) {
Expression out(value);
value = 1;
return out;
}
if (typeIs("double")) {
// If we have type "double" then we *are* a scalar!
Expression out(*this);
*this = Expression(1);
return out;
}
if (kindIs("*/") && name == "*") {
Expression sf1 = arg1->ScalarFactor();
Expression sf2 = arg2->ScalarFactor();
*this = *arg1 * *arg2; // to handle cases where arg1 or arg2 becomes 1.
return sf1*sf2;
}
if (kindIs("*/") && name == "/") {
Expression sf1 = arg1->ScalarFactor();
Expression sf2 = arg2->ScalarFactor();
*this = *arg1 / *arg2; // to handle cases where arg1 or arg2 becomes 1.
return sf1/sf2;
}
if (kindIs("linear function")) {
return arg1->ScalarFactor();
}
if (kindIs("unary") && name == "-") {
Expression postfactor = *arg1;
Expression prefactor = postfactor.ScalarFactor();
*this = postfactor;
return -prefactor;
}
return Expression(1);
}
