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Add infiniteness propagation to Map, Filter.

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This commit is contained in:
David Simcha 2010-06-18 02:31:03 +00:00
parent 2d576cfb8d
commit 73f91e5d72
1 changed files with 23 additions and 5 deletions
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28
std/algorithm.d
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@ -154,9 +154,14 @@ struct Map(alias fun, Range) if (isInputRange!(Range))
fillCache;
}
@property bool empty() {
return _input.empty;
}
static if(isInfinite!Range) {
// Propagate infinite-ness.
enum bool empty = false;
} else {
@property bool empty() {
return _input.empty;
}
}
void popFront() {
_input.popFront;
@ -255,9 +260,14 @@ unittest
assert(fibsSquares.front == 4);
fibsSquares.popFront;
assert(fibsSquares.front == 9);
auto repeatMap = map!"a"(repeat(1));
static assert(isInfinite!(typeof(repeatMap)));
auto intRange = map!"a"([1,2,3]);
static assert(isRandomAccessRange!(typeof(intRange)));
}
// reduce
/**
Implements the homonym function (also known as $(D accumulate), $(D
@ -554,7 +564,12 @@ struct Filter(alias pred, Range) if (isInputRange!(Range))
return this;
}
bool empty() { return _input.empty; }
static if(isInfinite!Range) {
enum bool empty = false;
} else {
bool empty() { return _input.empty; }
}
void popFront()
{
do
@ -578,6 +593,9 @@ unittest
a = [ 1, 22, 3, 42, 5 ];
auto under10 = filter!("a < 10")(a);
assert(equal(under10, [1, 3, 5][]));
auto infinite = filter!"a > 2"(repeat(3));
static assert(isInfinite!(typeof(infinite)));
}
// move