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Make Ranges Chainable through Concatenation Operator ~ #3353

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Make Ranges Chainable through Concatenation Operator ~ #3353

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38b1d3b
First try
nordlow Jun 1, 2015
1dd3bfb
Support consecutive chains
nordlow Jun 1, 2015
db59e25
Support map
nordlow Jun 1, 2015
19892ff
Support FilterBidiResult
nordlow Jun 1, 2015
ea15bd4
Support uniq
nordlow Jun 1, 2015
a359666
Support chain
nordlow Jun 1, 2015
007ed96
Use opBinary instead of opCat
nordlow Jun 1, 2015
74f3649
Add first try at documentation
nordlow Jun 1, 2015
592ffcc
Fix bug in cache unittest
nordlow Jun 1, 2015
07831aa
Support splitter
nordlow Jun 1, 2015
1e3ff0b
Use mixin joiner Result but comment out failing unittest
nordlow Jun 1, 2015
a8be293
Support choose and chooseAmong
nordlow Jun 1, 2015
895d9d5
Fix failing unittest for chooseAmong
nordlow Jun 1, 2015
92f0d6b
Support roundRobin
nordlow Jun 1, 2015
3593280
Add unittest for radial
nordlow Jun 1, 2015
6612f0b
Support take
nordlow Jun 1, 2015
110213a
Support takeExactly
nordlow Jun 1, 2015
6205e83
Support takeOne
nordlow Jun 1, 2015
756de79
Support take
nordlow Jun 1, 2015
6753e89
Assert that infinite ranges are only placed at the end of a chain
nordlow Jun 5, 2015
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29 changes: 28 additions & 1 deletion std/algorithm/iteration.d
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Original file line number Diff line number Diff line change
Expand Up @@ -212,6 +212,7 @@ same cost or side effects.
auto r2 = r.cache().take(3);

assert(equal(r1, [0, 1, 2]));
assert(equal(r1 ~ r1, [0, 1, 2, 0, 1, 2]));
assert(i == 2); //The last "seen" element was 2. The data in cache has been cleared.

assert(equal(r2, [0, 1, 2]));
Expand Down Expand Up @@ -412,6 +413,8 @@ private struct _Cache(R, bool bidir)
}
}
}

mixin Chainable;
}

/**
Expand Down Expand Up @@ -608,6 +611,8 @@ private struct MapResult(alias fun, Range)
return typeof(this)(_input.save);
}
}

mixin Chainable;
}

@safe unittest
Expand All @@ -620,7 +625,9 @@ private struct MapResult(alias fun, Range)
writeln("unittest @", __FILE__, ":", __LINE__, " done.");

alias stringize = map!(to!string);
assert(equal(stringize([ 1, 2, 3, 4 ]), [ "1", "2", "3", "4" ]));
auto s = stringize([ 1, 2, 3, 4 ]);
assert(equal(s, [ "1", "2", "3", "4" ]));
assert(equal(s ~ s, [ "1", "2", "3", "4", "1", "2", "3", "4" ]));

uint counter;
alias count = map!((a) { return counter++; });
Expand Down Expand Up @@ -1020,6 +1027,8 @@ private struct FilterResult(alias pred, Range)
return typeof(this)(_input.save);
}
}

mixin Chainable;
}

@safe unittest
Expand All @@ -1034,6 +1043,8 @@ private struct FilterResult(alias pred, Range)
auto r = filter!("a > 3")(a);
static assert(isForwardRange!(typeof(r)));
assert(equal(r, [ 4 ][]));
assert(equal(r ~ r, [ 4, 4][]));
assert(equal(r ~ r ~ r, [ 4, 4, 4][]));

a = [ 1, 22, 3, 42, 5 ];
auto under10 = filter!("a < 10")(a);
Expand Down Expand Up @@ -1152,6 +1163,7 @@ template filterBidirectional(alias pred)
static assert(isBidirectionalRange!(typeof(small)));
assert(small.back == 2);
assert(equal(small, [ 1, 2 ]));
assert(equal(small ~ small, [ 1, 2, 1, 2]));
assert(equal(retro(small), [ 2, 1 ]));
// In combination with chain() to span multiple ranges
int[] a = [ 3, -2, 400 ];
Expand Down Expand Up @@ -1204,6 +1216,8 @@ private struct FilterBidiResult(alias pred, Range)
{
return typeof(this)(_input.save);
}

mixin Chainable;
}

// group
Expand Down Expand Up @@ -2056,6 +2070,8 @@ if (isInputRange!RoR && isInputRange!(ElementType!RoR)
return copy;
}
}

mixin Chainable;
}
return Result(r, sep);
}
Expand All @@ -2079,6 +2095,11 @@ if (isInputRange!RoR && isInputRange!(ElementType!RoR)
assert(equal(joiner(["Mary", "has", "a", "little", "lamb"], "..."),
"Mary...has...a...little...lamb"));
assert(equal(joiner(["abc", "def"]), "abcdef"));
/* TODO This fails, as
iteration.d(2098,18): Error: incompatible types for ((joiner(["abc", "def"])) ~ (joiner(["abc", "def"]))): 'Result' and 'Result'
why?:
assert(equal(joiner(["abc", "def"]) ~ joiner(["abc", "def"]), "abcdefabcdef"));
*/
}

unittest
Expand Down Expand Up @@ -3741,6 +3762,8 @@ if (isSomeChar!C)
{
return this;
}

mixin Chainable;
}
return Result(s);
}
Expand All @@ -3751,6 +3774,7 @@ if (isSomeChar!C)
import std.algorithm.comparison : equal;
auto a = " a bcd ef gh ";
assert(equal(splitter(a), ["a", "bcd", "ef", "gh"][]));
assert(equal(splitter(a) ~ splitter(a), ["a", "bcd", "ef", "gh", "a", "bcd", "ef", "gh"][]));
}

@safe pure unittest
Expand Down Expand Up @@ -4157,6 +4181,8 @@ private struct UniqResult(alias pred, Range)
return typeof(this)(_input.save);
}
}

mixin Chainable;
}

@safe unittest
Expand All @@ -4172,6 +4198,7 @@ private struct UniqResult(alias pred, Range)
static assert(isForwardRange!(typeof(r)));

assert(equal(r, [ 1, 2, 3, 4, 5 ][]));
assert(equal(r ~ r, [ 1, 2, 3, 4, 5, 1, 2, 3, 4, 5 ][]));
assert(equal(retro(r), retro([ 1, 2, 3, 4, 5 ][])));

foreach (DummyType; AllDummyRanges) {
Expand Down
46 changes: 44 additions & 2 deletions std/range/package.d
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Original file line number Diff line number Diff line change
Expand Up @@ -858,6 +858,11 @@ if (Ranges.length > 0 &&

import std.typetuple : anySatisfy;

static if (anySatisfy!(isInfinite, R[0 .. $ - 1]))
{
static assert(false, "No sense in appending ranges after an infinite range in a chain.");
}

static if (anySatisfy!(isInfinite, R))
{
// Propagate infiniteness.
Expand Down Expand Up @@ -1106,6 +1111,16 @@ if (Ranges.length > 0 &&
}
return result;
}

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Why is this not doing the mixin?

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Because I needed a specialized logic for flattening of the chain-tree as mentioned below.

If this flattening is not needed we can reuse Chainable here, of course.

If not, I guess it's better to move this tree-flattening logic to Chainable...aah but because Result is a Voldemort type I don't think this is possible.

My plan now instead is to do something like

            auto opBinary(string op : "~", Range)(Range r)
            if (isInputRange!(Unqual!Range))
            {
                import std.range : chain;
                static if (isInstanceOf(Range, Result)) // if rhs r is a chain
                {
                    return chain(source, r.source); // flatten chain-tree
                }
                else
                {
                    return chain(source, r); // flatten chain-tree
                }
            }

Is there some way to check if rhs argument r is a chain?

What do you say?

Is this in vain?

auto opBinary(string op : "~", Range)(Range r)
if (isInputRange!(Unqual!Range)// &&
// is(CommonType!(RvalueElementType,
// ElementType!Range))
)
{
import std.range : chain;
return chain(source, r); // flatten tree
}
}
return Result(rs);
}
Expand Down Expand Up @@ -1168,13 +1183,16 @@ unittest
auto c = chain( iota(0, 10), iota(0, 10) );

// Test the case where infinite ranges are present.
auto inf = chain([0,1,2][], cycle([4,5,6][]), [7,8,9][]); // infinite range
auto inf = chain([0,1,2][], cycle([4,5,6][])); // infinite range
assert(inf[0] == 0);
assert(inf[3] == 4);
assert(inf[6] == 4);
assert(inf[7] == 5);
static assert(isInfinite!(typeof(inf)));

// Infinite ranges may only be placed at the end of a chain
static assert(!__traits(compiles, { auto inf = chain([0,1,2][], cycle([4,5,6][]), [7,8,9][]); }));

immutable int[] immi = [ 1, 2, 3 ];
immutable float[] immf = [ 1, 2, 3 ];
static assert(is(typeof(chain(immi, immf))));
Expand Down Expand Up @@ -1404,6 +1422,7 @@ if (isInputRange!(Unqual!R1) && isInputRange!(Unqual!R2) &&
else result.r2 = result.r2[begin .. end];
return result;
}
mixin Chainable;
}
return Result(condition, r1, r2);
}
Expand Down Expand Up @@ -1484,6 +1503,8 @@ unittest
uint[] foo = [1,2,3,4,5];
uint[] bar = [6,7,8,9,10];
auto c = chooseAmong(1,foo, bar);
assert(equal(c ~ c, [6,7,8,9,10,
6,7,8,9,10]));
assert(c[3] == 9);
c[3] = 42;
assert(c[3] == 42);
Expand Down Expand Up @@ -1609,6 +1630,8 @@ if (Rs.length > 1 && allSatisfy!(isInputRange, staticMap!(Unqual, Rs)))

alias opDollar = length;
}

mixin Chainable;
}

return Result(rs, 0);
Expand All @@ -1623,6 +1646,8 @@ if (Rs.length > 1 && allSatisfy!(isInputRange, staticMap!(Unqual, Rs)))
int[] b = [ 10, 20, 30, 40 ];
auto r = roundRobin(a, b);
assert(equal(r, [ 1, 10, 2, 20, 3, 30, 40 ]));
assert(equal(r ~ r, [ 1, 10, 2, 20, 3, 30, 40,
1, 10, 2, 20, 3, 30, 40 ]));
}

/**
Expand Down Expand Up @@ -1653,6 +1678,8 @@ if (isRandomAccessRange!(Unqual!R) && hasLength!(Unqual!R))
assert(equal(radial(a), [ 3, 4, 2, 5, 1 ]));
a = [ 1, 2, 3, 4 ];
assert(equal(radial(a), [ 2, 3, 1, 4 ]));
assert(equal(radial(a) ~ radial(a), [ 2, 3, 1, 4,
2, 3, 1, 4 ]));
}

@safe unittest
Expand Down Expand Up @@ -1875,6 +1902,8 @@ if (isInputRange!(Unqual!Range) &&
{
return _maxAvailable;
}

mixin Chainable;
}

// This template simply aliases itself to R and is useful for consistency in
Expand Down Expand Up @@ -1908,6 +1937,8 @@ if (isInputRange!(Unqual!R) && !isInfinite!(Unqual!R) && hasSlicing!(Unqual!R) &
assert(s.length == 5);
assert(s[4] == 5);
assert(equal(s, [ 1, 2, 3, 4, 5 ][]));
assert(equal(s ~ s, [ 1, 2, 3, 4, 5,
1, 2, 3, 4, 5 ][]));
}

// take(take(r, n1), n2)
Expand Down Expand Up @@ -2110,6 +2141,8 @@ if (isInputRange!R)
return _input.front = v;
}
}

mixin Chainable;
}

return Result(range, n);
Expand All @@ -2125,6 +2158,8 @@ if (isInputRange!R)

auto b = takeExactly(a, 3);
assert(equal(b, [1, 2, 3]));
assert(equal(b ~ b, [1, 2, 3,
1, 2, 3]));
static assert(is(typeof(b.length) == size_t));
assert(b.length == 3);
assert(b.front == 1);
Expand Down Expand Up @@ -2267,6 +2302,7 @@ auto takeOne(R)(R source) if (isInputRange!R)
}
// Non-standard property
@property R source() { return _source; }
mixin Chainable;
}

return Result(source, source.empty);
Expand All @@ -2276,7 +2312,10 @@ auto takeOne(R)(R source) if (isInputRange!R)
///
@safe unittest
{
import std.algorithm : equal;

auto s = takeOne([42, 43, 44]);
assert(equal(s ~ s, [42, 42]));
static assert(isRandomAccessRange!(typeof(s)));
assert(s.length == 1);
assert(!s.empty);
Expand Down Expand Up @@ -2701,6 +2740,7 @@ public:
private static struct DollarToken {}
enum opDollar = DollarToken.init;
auto opSlice(size_t, DollarToken) inout { return this; }
mixin Chainable;
}

/// Ditto
Expand All @@ -2711,7 +2751,9 @@ Repeat!T repeat(T)(T value) { return Repeat!T(value); }
{
import std.algorithm : equal;

assert(equal(5.repeat().take(4), [ 5, 5, 5, 5 ]));
assert(equal(5.repeat.take(4), [ 5, 5, 5, 5 ]));
assert(equal((1.repeat.take(2) ~ 5.repeat).take(4), [ 1, 1,
5, 5 ]));
}

@safe unittest
Expand Down
19 changes: 19 additions & 0 deletions std/range/primitives.d
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Expand Up @@ -2239,3 +2239,22 @@ if (!isNarrowString!(T[]))
size_t i = a.length - std.utf.strideBack(a, a.length);
return decode(a, i);
}

/**
This template shall be mixed in at the top-scope inside of the $(D Result)
struct of each $(D InputRange) in order to support lazy chaining via
concatenation operation as `x ~ y` instead of via $(D chain(x, y))).
*/
template Chainable()
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Documentation?

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First try is done.

{
import std.traits: Unqual, CommonType;
import std.range: ElementType;
auto opBinary(string op : "~", Range)(Range r)
if (isInputRange!(Unqual!Range) &&
is(CommonType!(ElementType!(typeof(this)),
ElementType!Range)))
{
import std.range : chain;
return chain(this, r);
}
}