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add Slice.toHash
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@9il
9il committed Jul 31, 2016
1 parent d7a7173 commit 4866f6c
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Showing 3 changed files with 217 additions and 11 deletions.
8 changes: 4 additions & 4 deletions std/digest/murmurhash.d
View file
Expand Up @@ -200,15 +200,15 @@ struct MurmurHash3(uint size /* 32 or 128 */ , uint opt = size_t.sizeof == 8 ? 6

alias Element = uint[4]; /// The element type for 128-bit implementation.

this(uint seed4, uint seed3, uint seed2, uint seed1)
this(uint seed4, uint seed3, uint seed2, uint seed1) pure nothrow @nogc
{
h4 = seed4;
h3 = seed3;
h2 = seed2;
h1 = seed1;
}

this(uint seed)
this(uint seed) pure nothrow @nogc
{
h4 = h3 = h2 = h1 = seed;
}
Expand Down Expand Up @@ -339,12 +339,12 @@ struct MurmurHash3(uint size /* 32 or 128 */ , uint opt = size_t.sizeof == 8 ? 6

alias Element = ulong[2]; /// The element type for 128-bit implementation.

this(ulong seed)
this(ulong seed) pure nothrow @nogc
{
h2 = h1 = seed;
}

this(ulong seed2, ulong seed1)
this(ulong seed2, ulong seed1) pure nothrow @nogc
{
h2 = seed2;
h1 = seed1;
Expand Down
220 changes: 213 additions & 7 deletions std/experimental/ndslice/slice.d
View file
Expand Up @@ -1124,7 +1124,7 @@ struct Slice(size_t _N, _Range)
alias DeepElemType = Slice!(Range.N - 1, Range.Range);

enum hasAccessByRef = isPointer!PureRange ||
__traits(compiles, { auto a = &(_ptr[0]); } );
__traits(compiles, &_ptr[0]);

enum PureIndexLength(Slices...) = Filter!(isIndex, Slices).length;

Expand Down Expand Up @@ -1431,7 +1431,7 @@ struct Slice(size_t _N, _Range)
assert(!empty!dimension);
static if (PureN == 1)
{
static if (__traits(compiles,{ auto _f = _ptr.front; }))
static if (__traits(compiles, _ptr.front ))
return _ptr.front;
else
return _ptr[0];
Expand Down Expand Up @@ -1464,7 +1464,7 @@ struct Slice(size_t _N, _Range)
if (dimension == 0)
{
assert(!empty!dimension);
static if (__traits(compiles, { _ptr.front = value; }))
static if (__traits(compiles, _ptr.front = value))
return _ptr.front = value;
else
return _ptr[0] = value;
Expand Down Expand Up @@ -1750,6 +1750,184 @@ struct Slice(size_t _N, _Range)
assert(iotaSlice(2, 3).slice.dropExactly!0(2) == iotaSlice([4, 3], 2).dropExactly!0(4));
}

/++
Computes hash value using MurmurHash3 algorithms without the finalization step.
Built-in associative arrays have the finalization step.
Returns: Hash value type of `size_t`.
See_also: $(LREF Slice.toMurmurHash3), $(MREF std, _digest, murmurhash).
+/
size_t toHash() const
{
static if (size_t.sizeof == 8)
{
auto ret = toMurmurHash3!128;
return ret[0] ^ ret[1];
}
else
{
return toMurmurHash3!32;
}
}

static if (doUnittest)
///
pure nothrow @nogc @safe
unittest
{
import std.experimental.ndslice.selection : iotaSlice;
const sl = iotaSlice(3, 7);
size_t hash = sl.toHash;
}

static if (doUnittest)
///
pure nothrow
unittest
{
import std.experimental.ndslice.iteration : allReversed;
import std.experimental.ndslice.selection : iotaSlice;

// hash is the same for allocated data and for generated data
auto a = iotaSlice(3, 7);
auto b = iotaSlice(3, 7).slice;

assert(a.toHash == b.toHash);
assert(typeid(typeof(a)).getHash(&a) == typeid(typeof(b)).getHash(&b));

// hash does not depend on strides
a = iotaSlice(3, 7).allReversed;
b = iotaSlice(3, 7).allReversed.slice;

assert(a.toHash == b.toHash);
assert(typeid(typeof(a)).getHash(&a) == typeid(typeof(b)).getHash(&b));
}

/++
Computes hash value using MurmurHash3 algorithms without the finalization step.
Returns:
Hash value type of `MurmurHash3!(size, opt).get()`.
See_also: $(LREF Slice.toHash), $(MREF std, _digest, murmurhash)
+/
auto toMurmurHash3(uint size /* 32 or 128 */ , uint opt = size_t.sizeof == 8 ? 64 : 32)() const
{
import std.digest.murmurhash : MurmurHash3;
enum msg = "unable to compute hash value for type " ~ DeepElemType.stringof;
static if (size_t.sizeof == 8)
auto hasher = MurmurHash3!(size, opt)(length);
else
auto hasher = MurmurHash3!(size, opt)(cast(uint) length);
enum hasMMH3 = __traits(compiles, {
MurmurHash3!(size, opt) hasher;
foreach (elem; (Unqual!This).init)
hasher.putElement(elem.toMurmurHash3!(size, opt));
});
static if (PureN == 1 && !hasMMH3)
{
static if (ElemType.sizeof <= 8 * hasher.Element.sizeof && __traits(isPOD, ElemType))
{
alias E = Unqual!ElemType;
}
else
{
alias E = size_t;
}
enum K = hasher.Element.sizeof / E.sizeof + bool(hasher.Element.sizeof % E.sizeof != 0);
enum B = E.sizeof / hasher.Element.sizeof + bool(E.sizeof % hasher.Element.sizeof != 0);
static assert (K == 1 || B == 1);
static union U
{
hasher.Element[B] blocks;
E[K] elems;
}
U u;
auto r = cast(Unqual!This) this;
// if element is smaller then blocks
static if (K > 1)
{
// cut tail composed of elements from the front
if (auto rem = r.length % K)
{
do
{
static if (is(E == Unqual!ElemType))
u.elems[rem] = r.front;
else
static if (__traits(compiles, r.front.toHash))
u.elems[rem] = r.front.toHash;
else
static if (__traits(compiles, typeid(ElemType).getHash(&r.front)))
u.elems[rem] = typeid(ElemType).getHash(&r.front);
else
{
auto f = r.front;
u.elems[rem] = typeid(ElemType).getHash(&f);
}

r.popFront;
}
while (--rem);
hasher.putElement(u.blocks[0]);
}
}
// if hashing elements in memory
static if (is(E == ElemType) && (isPointer!Range || isDynamicArray!Range))
{
import std.math : isPowerOf2;
// .. and elements can fill entire block
static if (ElemType.sizeof.isPowerOf2)
{
// then try to optimize blocking
if (stride == 1)
{
static if (isPointer!Range)
{
hasher.putElements(cast(hasher.Element[]) r._ptr[0 .. r.length]);
}
else
{
hasher.putElements(cast(hasher.Element[]) r._ptr._range[r._ptr._shift .. r.length + r._ptr._shift]);
}
return hasher.get;
}
}
}
while (r.length)
{
foreach (k; Iota!(0, K))
{
static if (is(E == Unqual!ElemType))
u.elems[k] = r.front;
else
static if (__traits(compiles, r.front.toHash))
u.elems[k] = r.front.toHash;
else
static if (__traits(compiles, typeid(ElemType).getHash(&r.front)))
u.elems[k] = typeid(ElemType).getHash(&r.front);
else
{
auto f = r.front;
u.elems[k] = typeid(ElemType).getHash(&f);
}
r.popFront;
}
foreach (b; Iota!(0, B))
{
hasher.putElement(u.blocks[b]);
}
}
}
else
{
foreach (elem; cast(Unqual!This) this)
hasher.putElement(elem.toMurmurHash3!(size, opt));
}
return hasher.get;
}

_Slice opSlice(size_t dimension)(size_t i, size_t j)
if (dimension < N)
in {
Expand Down Expand Up @@ -2587,7 +2765,7 @@ pure nothrow unittest

// `opIndexAssing` accepts only fully defined indexes and slices.
// Use an additional empty slice `[]`.
static assert(!__traits(compiles), tensor[0 .. 2] *= 2);
static assert(!__traits(compiles, tensor[0 .. 2] *= 2));

tensor[0 .. 2][] *= 2; //OK, empty slice
tensor[0 .. 2, 3, 0..$] /= 2; //OK, 3 index or slice positions are defined.
Expand Down Expand Up @@ -2750,7 +2928,8 @@ unittest
// Container Array
import std.container.array;
Array!int ar;
static assert(is(typeof(ar[].sliced(3, 4)) == Slice!(2, typeof(ar[]))));
ar.length = 12;
Slice!(2, typeof(ar[])) arSl = ar[].sliced(3, 4);

// Implicit conversion of a range to its unqualified type.
import std.range : iota;
Expand Down Expand Up @@ -2912,7 +3091,7 @@ private struct PtrShell(Range)
Range _range;

enum hasAccessByRef = isPointer!Range ||
__traits(compiles, { auto a = &(_range[0]); } );
__traits(compiles, &_range[0]);

void opOpAssign(string op)(sizediff_t shift)
if (op == `+` || op == `-`)
Expand Down Expand Up @@ -3033,6 +3212,33 @@ pure nothrow unittest
}
}

// toHash test
unittest
{
import std.conv : to;
import std.complex;
import std.experimental.ndslice.iteration : allReversed;

static assert(__traits(isPOD, uint[2]));
static assert(__traits(isPOD, double));
static assert(__traits(isPOD, Complex!double));

foreach (T; AliasSeq!(
byte, short, int, long,
float, double, real,
Complex!float, Complex!double, Complex!real))
{
auto a = slice!(T, No.replaceArrayWithPointer)(3, 7);
auto b = slice!T(3, 7).allReversed;
size_t i;
foreach (row; a)
foreach (ref e; row)
e = to!T(i++);
b[] = a;
assert(typeid(a.This).getHash(&a) == typeid(b.This).getHash(&b), T.stringof);
}
}

unittest
{
int[] arr = [1, 2, 3];
Expand Down Expand Up @@ -3128,7 +3334,7 @@ private template PtrTupleFrontMembers(Names...)
enum PtrTupleFrontMembers = PtrTupleFrontMembers!Top
~ "
@property auto ref " ~ Names[$-1] ~ "() {
static if (__traits(compiles,{ auto _f = _ptrs__[" ~ m.stringof ~ "].front; }))
static if (__traits(compiles, _ptrs__[" ~ m.stringof ~ "].front()))
return _ptrs__[" ~ m.stringof ~ "].front;
else
return _ptrs__[" ~ m.stringof ~ "][0];
Expand Down
Binary file added std/experimental/ndslice/slice.o
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