public void SelectBothCompositionLawHolds(IRoseTree <int, string> t)
{
char f(bool b) => b ? 'T' : 'F';
bool g(int x) => x % 2 == 0;
bool h(int x) => x % 2 == 0;
int i(string s) => s.Length;
Assert.Equal(
t.SelectBoth(x => f(g(x)), y => h(i(y))),
t.SelectBoth(g, i).SelectBoth(f, h));
}
public void ConsistencyLawHolds(IRoseTree <int, string> t)
{
DateTime f(int i) => new DateTime(i);
bool g(string s) => string.IsNullOrWhiteSpace(s);
Assert.Equal(t.SelectBoth(f, g), t.SelectLeaf(g).SelectNode(f));
Assert.Equal(
t.SelectNode(f).SelectLeaf(g),
t.SelectLeaf(g).SelectNode(f));
}
public static IRoseTree <N, L1> SelectLeaf <N, L, L1>(
this IRoseTree <N, L> source,
Func <L, L1> selector)
{
return(source.SelectBoth(n => n, selector));
}
public void SelectBothObeysIdentityLaw(IRoseTree <int, string> t)
{
Assert.Equal(t, t.SelectBoth(Id, Id));
}
public static IRoseTree <N1, L> SelectNode <N, N1, L>(
this IRoseTree <N, L> source,
Func <N, N1> selector)
{
return(source.SelectBoth(selector, l => l));
}