Add take range adapter

This commit is contained in:
Eugen Wissner 2018-03-25 08:17:38 +02:00
parent 7357503c5a
commit cd9960db2a

View File

@ -15,5 +15,289 @@
*/ */
module tanya.range; module tanya.range;
import tanya.algorithm.mutation;
import tanya.math;
public import tanya.range.array; public import tanya.range.array;
public import tanya.range.primitive; public import tanya.range.primitive;
/**
*
*/
struct Take(R)
if (isInputRange!R)
{
private R source;
size_t length_;
@disable this();
private this(R source, size_t length)
{
this.source = source;
static if (hasLength!R)
{
this.length_ = min(source.length, length);
}
else
{
this.length_ = length;
}
}
@property auto ref front()
in
{
assert(!empty);
}
do
{
return this.source.front;
}
void popFront()
in
{
assert(!empty);
}
do
{
this.source.popFront();
--this.length_;
}
@property bool empty()
{
static if (isInfinite!R)
{
return length == 0;
}
else
{
return length == 0 || this.source.empty;
}
}
@property size_t length()
{
return this.length_;
}
static if (hasMobileElements!R)
{
auto moveFront()
in
{
assert(!empty);
}
do
{
return this.source.moveFront();
}
}
static if (hasAssignableElements!R)
{
@property void front(ref ElementType!R value)
in
{
assert(!empty);
}
do
{
this.source.front = value;
}
@property void front(ElementType!R value)
in
{
assert(!empty);
}
do
{
this.source.front = move(value);
}
}
static if (isForwardRange!R)
{
typeof(this) save()
{
return typeof(this)(this.source.save(), length);
}
}
static if (isRandomAccessRange!R)
{
@property auto ref back()
in
{
assert(!empty);
}
do
{
return this.source[this.length - 1];
}
void popBack()
in
{
assert(!empty);
}
do
{
--this.length_;
}
auto ref opIndex(size_t i)
in
{
assert(i < length);
}
do
{
return this.source[i];
}
static if (hasMobileElements!R)
{
auto moveBack()
in
{
assert(!empty);
}
do
{
return this.source.moveAt(length - 1);
}
auto moveAt(size_t i)
in
{
assert(i < length);
}
do
{
return this.source.moveAt(i);
}
}
static if (hasAssignableElements!R)
{
@property void back(ref ElementType!R value)
in
{
assert(!empty);
}
do
{
this.source[length - 1] = value;
}
@property void back(ElementType!R value)
in
{
assert(!empty);
}
do
{
this.source[length - 1] = move(value);
}
void opIndexAssign(ref ElementType!R value, size_t i)
in
{
assert(i < length);
}
do
{
this.source[i] = value;
}
void opIndexAssign(ElementType!R value, size_t i)
in
{
assert(i < length);
}
do
{
this.source[i] = move(value);
}
}
}
static if (hasSlicing!R)
{
auto opSlice(size_t i, size_t j)
in
{
assert(i <= j);
assert(j <= length);
}
do
{
return take(this.source[i .. j], length);
}
}
}
/**
* ditto
*/
Take!R take(R)(R range, size_t n)
if (isInputRange!R)
{
return Take!R(range, n);
}
///
@nogc nothrow pure @safe unittest
{
static struct InfiniteRange
{
private size_t front_ = 1;
enum bool empty = false;
@property size_t front() @nogc nothrow pure @safe
{
return this.front_;
}
@property void front(size_t i) @nogc nothrow pure @safe
{
this.front_ = i;
}
void popFront() @nogc nothrow pure @safe
{
++this.front_;
}
size_t opIndex(size_t i) @nogc nothrow pure @safe
{
return this.front_ + i;
}
void opIndexAssign(size_t value, size_t i) @nogc nothrow pure @safe
{
this.front = i + value;
}
InfiniteRange save() @nogc nothrow pure @safe
{
return this;
}
}
auto t = InfiniteRange().take(3);
assert(t.length == 3);
assert(t.front == 1);
assert(t.back == 3);
t.popFront();
assert(t.front == 2);
assert(t.back == 3);
t.popBack();
assert(t.front == 2);
assert(t.back == 2);
t.popFront();
assert(t.empty);
}