Feature: iter\empty or add limit to iter\count

[SamMousa]

Currently we have count() to count the number of elements in an iterator.

I'd love a function empty() that tells me wether an iterable is empty or not.
This could be done separately, alternatively it might be more flexible to add a limit to count:

Many uses for count compare it with some number anyway, no sense wasting time counting beyond it.

function inf() { 
    $i = 0;
    while(true) {
        yield $i++;
    }
}

function thousand() { 
    $i = 0;
    while($i < 1000) {
        yield $i++;
    }
}

// Check if empty. [infinite loop]
if (count(inf()) > 0) {

}

// Check if contains at least 50 elements. [infinite loop]
if (count(inf()) > 50) {

}

// Check if contains at least 50 elements. [1000 iterations, 950 useless]
if (count(thousand()) > 50) {

}

// Check if empty. [1000 iterations, 999 useless]
if (count(empty()) > 0) {

}

Adding a limit to count would resolve these issues:

function inf() { 
    $i = 0;
    while(true) {
        yield $i++;
    }
}

function thousand() { 
    $i = 0;
    while($i < 1000) {
        yield $i++;
    }
}


// Check if empty. [1 iterations]
if (count(inf(), 1) > 0) {

}

// Check if contains at least 50 elements. [50 iterations]
if (count(inf(), 51) > 50) {

}

// Check if contains at least 50 elements. [1000 iterations]
if (count(thousand(), 51) > 50) {

}

// Check if empty. [1 iteration]
if (count(thousand(), 1) > 0) {

}

[nikic]

The parameter on count() seems rather confusing to me -- I wouldn't be able to guess what this does just by looking at the code. It's possible to obtain the same result using a combination of count and take though: if (count(take($it, 51)) > 50), which I think it clearer than the extra parameter on count().

Agree on the empty though, that looks useful. As empty is a reserved keyword, it would have to be something like isEmpty() though.

[nikic]

isEmpty() function added in fed36b4 and released as part of v1.6.0.