On Mon, 12 Jul 2010 22:58:07 -0400, Andrei Alexandrescu
<[email protected]> wrote:
On 07/12/2010 04:39 PM, Steven Schveighoffer wrote:
On Mon, 12 Jul 2010 17:25:43 -0400, Andrei Alexandrescu
<[email protected]> wrote:
On 07/12/2010 02:41 PM, Steven Schveighoffer wrote:
I'm unsure how it will work either. I admit now that I didn't think
through how this will be used.
It's very simple. As far as a user of an output range is concerned,
they should write stuff like:
put(r, '[');
char[] someBuf;
put(r, someBuf);
put(r, ", ");
put(r, ']');
in confidence that things are reasonably efficient.
How does that work for a range whose front() can be assigned a dchar?
Wait, it doesn't, because it won't compile.
But wouldn't that be the same for a delegate that takes a dchar?
I'm very confused at what you are trying to do. I expected that a char[]
would be a valid output range.
Actually a char[] is not a valid output range. Overwriting
variable-length codes with other variable-length codes might mess up the
string.
Hm... I think it should be, and here is why. Imagine this situation:
char[1024] buffer = void; // allocate some blank space on the stack
put(buffer, someInputRange);
But the above won't compile anyways, because a ref char[1024] isn't a
range, and even if it was, it would be left in a state where it pointed to
the uninitialized data. What we need is a helper struct, and then we are
covered.
char[1024] buffer = void;
CharBuilder builder(buffer[]); // defines put
put(builder, someInputRange);
So I think we are good. Does Appender work here?
Here's what I have. Works?
void put(R, E)(ref R r, E e)
{
static if (!isArray!R && is(typeof(r.put(e))))
{
r.put(e);
}
else static if (!isArray!R && is(typeof(r.put((&e)[0..1]))))
{
r.put((&e)[0..1]);
}
else static if (is(typeof(r.front = e, r.popFront())))
{
r.front = e;
r.popFront();
}
else static if (isInputRange!E && is(typeof(put(r, e.front))))
{
for (; !e.empty; e.popFront()) put(r, e.front);
}
else static if (is(typeof(r(e))))
{
r(e);
}
else static if (is(typeof(r((&e)[0..1]))))
{
r((&e)[0..1]);
}
else
{
static assert(false, "Cannot put a "~E.stringof~" into a
"~R.stringof);
}
}
That is satisfactory, it encompasses what I was saying, thanks!
-Steve
