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Simen Kjærås
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1 changed files with 157 additions and 60 deletions
217
std/functional.d
217
std/functional.d
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@ -1289,6 +1289,15 @@ alias pipe(fun...) = compose!(Reverse!(fun));
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assert(compose!(`a + 0.5`, `to!(int)(a) + 1`, foo)(1) == 2.5);
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}
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private template getOverloads(alias fun)
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{
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import std.meta : AliasSeq;
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static if (__traits(compiles, __traits(getOverloads, __traits(parent, fun), __traits(identifier, fun), true)))
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alias getOverloads = __traits(getOverloads, __traits(parent, fun), __traits(identifier, fun), true);
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else
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alias getOverloads = AliasSeq!fun;
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}
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/**
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* $(LINK2 https://en.wikipedia.org/wiki/Memoization, Memoizes) a function so as
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* to avoid repeated computation. The memoization structure is a hash table keyed by a
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@ -1324,87 +1333,131 @@ Note:
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*/
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template memoize(alias fun)
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{
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import std.traits : ReturnType;
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// https://issues.dlang.org/show_bug.cgi?id=13580
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// alias Args = Parameters!fun;
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import std.traits : Parameters;
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import std.meta : anySatisfy;
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ReturnType!fun memoize(Parameters!fun args)
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// Specific overloads:
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alias overloads = getOverloads!fun;
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static foreach (fn; overloads)
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static if (is(Parameters!fn))
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alias memoize = impl!(Parameters!fn);
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enum isTemplate(alias a) = __traits(isTemplate, a);
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static if (anySatisfy!(isTemplate, overloads))
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{
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alias Args = Parameters!fun;
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import std.typecons : Tuple;
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// Generic implementation
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alias memoize = impl;
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}
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auto impl(Args...)(Args args) if (is(typeof(fun(args))))
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{
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import std.typecons : Tuple, tuple;
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import std.traits : Unqual;
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static Unqual!(ReturnType!fun)[Tuple!Args] memo;
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auto t = Tuple!Args(args);
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if (auto p = t in memo)
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return *p;
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auto r = fun(args);
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memo[t] = r;
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return r;
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static if (args.length > 0)
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{
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static Unqual!(typeof(fun(args)))[Tuple!(typeof(args))] memo;
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auto t = Tuple!Args(args);
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if (auto p = t in memo)
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return *p;
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auto r = fun(args);
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memo[t] = r;
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return r;
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}
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else
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{
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static typeof(fun(args)) result;
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result = fun(args);
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return result;
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}
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}
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}
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/// ditto
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template memoize(alias fun, uint maxSize)
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{
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import std.traits : ReturnType;
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// https://issues.dlang.org/show_bug.cgi?id=13580
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// alias Args = Parameters!fun;
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ReturnType!fun memoize(Parameters!fun args)
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import std.traits : Parameters;
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import std.meta : anySatisfy;
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// Specific overloads:
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alias overloads = getOverloads!fun;
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static foreach (fn; overloads)
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static if (is(Parameters!fn))
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alias memoize = impl!(Parameters!fn);
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enum isTemplate(alias a) = __traits(isTemplate, a);
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static if (anySatisfy!(isTemplate, overloads))
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{
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import std.meta : staticMap;
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import std.traits : hasIndirections, Unqual;
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import std.typecons : tuple;
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static struct Value { staticMap!(Unqual, Parameters!fun) args; Unqual!(ReturnType!fun) res; }
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static Value[] memo;
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static size_t[] initialized;
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// Generic implementation
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alias memoize = impl;
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}
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if (!memo.length)
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auto impl(Args...)(Args args) if (is(typeof(fun(args))))
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{
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static if (args.length > 0)
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{
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import core.memory : GC;
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import std.meta : staticMap;
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import std.traits : hasIndirections, Unqual;
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import std.typecons : tuple;
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alias returnType = typeof(fun(args));
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static struct Value { staticMap!(Unqual, Args) args; Unqual!returnType res; }
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static Value[] memo;
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static size_t[] initialized;
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// Ensure no allocation overflows
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static assert(maxSize < size_t.max / Value.sizeof);
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static assert(maxSize < size_t.max - (8 * size_t.sizeof - 1));
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if (!memo.length)
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{
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import core.memory : GC;
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enum attr = GC.BlkAttr.NO_INTERIOR | (hasIndirections!Value ? 0 : GC.BlkAttr.NO_SCAN);
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memo = (cast(Value*) GC.malloc(Value.sizeof * maxSize, attr))[0 .. maxSize];
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enum nwords = (maxSize + 8 * size_t.sizeof - 1) / (8 * size_t.sizeof);
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initialized = (cast(size_t*) GC.calloc(nwords * size_t.sizeof, attr | GC.BlkAttr.NO_SCAN))[0 .. nwords];
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}
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// Ensure no allocation overflows
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static assert(maxSize < size_t.max / Value.sizeof);
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static assert(maxSize < size_t.max - (8 * size_t.sizeof - 1));
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import core.bitop : bt, bts;
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import core.lifetime : emplace;
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enum attr = GC.BlkAttr.NO_INTERIOR | (hasIndirections!Value ? 0 : GC.BlkAttr.NO_SCAN);
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memo = (cast(Value*) GC.malloc(Value.sizeof * maxSize, attr))[0 .. maxSize];
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enum nwords = (maxSize + 8 * size_t.sizeof - 1) / (8 * size_t.sizeof);
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initialized = (cast(size_t*) GC.calloc(nwords * size_t.sizeof, attr | GC.BlkAttr.NO_SCAN))[0 .. nwords];
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}
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size_t hash;
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foreach (ref arg; args)
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hash = hashOf(arg, hash);
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// cuckoo hashing
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immutable idx1 = hash % maxSize;
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if (!bt(initialized.ptr, idx1))
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{
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emplace(&memo[idx1], args, fun(args));
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// only set to initialized after setting args and value
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// https://issues.dlang.org/show_bug.cgi?id=14025
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bts(initialized.ptr, idx1);
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import core.bitop : bt, bts;
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import core.lifetime : emplace;
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size_t hash;
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foreach (ref arg; args)
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hash = hashOf(arg, hash);
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// cuckoo hashing
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immutable idx1 = hash % maxSize;
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if (!bt(initialized.ptr, idx1))
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{
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emplace(&memo[idx1], args, fun(args));
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// only set to initialized after setting args and value
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// https://issues.dlang.org/show_bug.cgi?id=14025
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bts(initialized.ptr, idx1);
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return memo[idx1].res;
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}
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else if (memo[idx1].args == args)
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return memo[idx1].res;
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// FNV prime
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immutable idx2 = (hash * 16_777_619) % maxSize;
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if (!bt(initialized.ptr, idx2))
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{
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emplace(&memo[idx2], memo[idx1]);
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bts(initialized.ptr, idx2);
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}
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else if (memo[idx2].args == args)
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return memo[idx2].res;
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else if (idx1 != idx2)
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memo[idx2] = memo[idx1];
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memo[idx1] = Value(args, fun(args));
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return memo[idx1].res;
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}
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else if (memo[idx1].args == args)
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return memo[idx1].res;
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// FNV prime
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immutable idx2 = (hash * 16_777_619) % maxSize;
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if (!bt(initialized.ptr, idx2))
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else
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{
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emplace(&memo[idx2], memo[idx1]);
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bts(initialized.ptr, idx2);
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static typeof(fun(args)) result;
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result = fun(args);
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return result;
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}
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else if (memo[idx2].args == args)
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return memo[idx2].res;
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else if (idx1 != idx2)
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memo[idx2] = memo[idx1];
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memo[idx1] = Value(args, fun(args));
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return memo[idx1].res;
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}
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}
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@ -1464,6 +1517,37 @@ unittest
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assert(fact(10) == 3628800);
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}
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// Issue 20099
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@system unittest // not @safe due to memoize
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{
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int i = 3;
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alias a = memoize!((n) => i + n);
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alias b = memoize!((n) => i + n, 3);
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assert(a(3) == 6);
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assert(b(3) == 6);
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}
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@system unittest // not @safe due to memoize
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{
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static Object objNum(int a) { return new Object(); }
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assert(memoize!objNum(0) is memoize!objNum(0U));
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assert(memoize!(objNum, 3)(0) is memoize!(objNum, 3)(0U));
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}
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@system unittest // not @safe due to memoize
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{
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struct S
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{
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static int fun() { return 0; }
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static int fun(int i) { return 1; }
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}
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assert(memoize!(S.fun)() == 0);
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assert(memoize!(S.fun)(3) == 1);
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assert(memoize!(S.fun, 3)() == 0);
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assert(memoize!(S.fun, 3)(3) == 1);
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}
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@system unittest // not @safe due to memoize
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{
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import core.math : sqrt;
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@ -1626,6 +1710,19 @@ unittest
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}}
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}
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// memoize should continue to work with functions that cannot be evaluated at compile time
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@system unittest
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{
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__gshared string[string] glob;
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static bool foo()
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{
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return (":-)" in glob) is null;
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}
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assert(memoize!foo);
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}
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private struct DelegateFaker(F)
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{
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import std.typecons : FuncInfo, MemberFunctionGenerator;
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