/*
Kommutativgesetze => a and b = b and a
=> a or b = b or a
Assoziativgesetze => (a and b) and c = a and (b and c)
=> (a or b) or c = a or (b or c)
[OK] Idempotenzgesetze => a and a=a
=> a or a=a
[OK] Distributivgesetze => a and (b or c) = (a and b) or (a and c)
=> a or (b and c) = (a or b) and (a or c)
[OK] Neutralitätsgesetze => a and 1 = a
=> a or 0 = a
[OK] Extremalgesetze => a and 0=0
=> a or 1=1
[OK] Doppelnegationsgesetz => not( not a)=a
[OK] De Morgansche Gesetze => not(a and b)= not a or not b
=> not(a or b)= not a and not b
[OK] Komplementärgesetze => a and not a=0
=> a or not a=1
[OK] Dualitätsgesetze => not 0 = 1
=> not 1 = 0
[OK] Absorptionsgesetze => a or(a and b)=a
=> a and(a or b)=a
*/
public ASTNode simplify(ASTNode term, final IExpressionContext context) {
if (term instanceof BooleanExpression) {
final BooleanExpression expr = (BooleanExpression) term;
ASTNode left = simplifyTerm(expr.getLHS(), context);
ASTNode right = simplifyTerm(expr.getRHS(), context);
return new BooleanExpression(left, right);
}
return simplifyTerm(term, context);
}
/**
* Tries to reduce a term by replacing expressions that evaluate to a literal value (true or
* false) with the corresponding value.
*
* @param term
* @param context
* @return
*/
public ASTNode reduce(ASTNode term, final IExpressionContext context) {
if (term instanceof BooleanExpression) {
final BooleanExpression expr = (BooleanExpression) term;
ASTNode left = internalReduce(expr.getLHS(), context);
ASTNode right = internalReduce(expr.getRHS(), context);
return new BooleanExpression(left, right);
}
return internalReduce(term, context);
}
public Boolean isTrue(BooleanExpression expr, IExpressionContext context) {
ASTNode lhs = expr.getLHS();
ASTNode rhs = expr.getRHS();
ASTNode value1 = lhs.evaluate(context);
ASTNode value2 = rhs.evaluate(context);
if (value1 != null && value2 != null) {
return value1.isEquivalent(value2, context);
}
return null;
}