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Merge pull request #84 from n8sh/inoutConstIteration 

In tanya.algorithm.iteration.take & retro preserve const/inout for `empty`/`front`/etc.
This commit is contained in:
Eugen Wissner 2019-03-29 08:36:50 +01:00 committed by GitHub
parent 2b8471fe34 10afe47bae
commit b55bb767e5
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1 changed files with 87 additions and 41 deletions
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128
source/tanya/algorithm/iteration.d
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@ -27,6 +27,50 @@ import tanya.meta.transform;
import tanya.range;
import tanya.typecons;
// These predicates are used to help preserve `const` and `inout` for
// ranges built on other ranges.
private enum hasInoutFront(T) = is(typeof((inout ref T a) => a.front));
private enum hasInoutBack(T) = is(typeof((inout ref T a) => a.back));
private enum hasInoutIndex(T) = is(typeof((inout ref T a, size_t i) => a[i]));
private enum hasConstEmpty(T) = is(typeof(((const T* a) => (*a).empty)(null)) : bool);
private enum hasConstLength(T) = is(typeof(((const T* a) => (*a).length)(null)) : size_t);
private enum hasConstSave(T) = is(typeof(((const T* a) => (*a).save())(null)) : T);
private enum hasConstSlice(T) = is(typeof(((const T* a) => (*a)[0 .. $])(null)) : T);
unittest
{
// Test the definitions.
static assert(hasInoutFront!string);
static assert(hasInoutBack!string);
static assert(hasInoutIndex!string);
static assert(hasConstEmpty!string);
static assert(hasConstLength!string);
static assert(hasConstSave!string);
static assert(hasConstSlice!string);
// Test that Take propagates const/inout correctly.
alias TakeString = Take!(string, false);
static assert(hasInoutFront!TakeString);
static assert(hasInoutBack!TakeString);
static assert(hasInoutIndex!TakeString);
static assert(hasConstEmpty!TakeString);
static assert(hasConstLength!TakeString);
static assert(hasConstSave!TakeString);
static assert(hasConstSlice!TakeString);
// Test that Retro propagates const/inout correctly.
alias RetroString = Retro!string;
static assert(hasInoutFront!RetroString);
static assert(hasInoutBack!RetroString);
static assert(hasInoutIndex!RetroString);
static assert(hasConstEmpty!RetroString);
static assert(hasConstLength!RetroString);
static assert(hasConstSave!RetroString);
static assert(hasConstSlice!RetroString);
}
private struct Take(R, bool exactly)
{
private R source;
@ -47,11 +91,11 @@ private struct Take(R, bool exactly)
}
}
@property auto ref front()
in (!empty)
mixin(`@property auto ref front() ` ~ (hasInoutFront!R ? `inout ` : ``) ~
`in (!empty)
{
return this.source.front;
}
}`);
void popFront()
in (!empty)
@ -60,8 +104,8 @@ private struct Take(R, bool exactly)
--this.length_;
}
@property bool empty()
{
mixin(`@property bool empty() ` ~ (exactly || isInfinite!R || hasConstEmpty!R ? `const ` : ``) ~
`{
static if (exactly || isInfinite!R)
{
return length == 0;
@ -70,11 +114,11 @@ private struct Take(R, bool exactly)
{
return this.length_ == 0 || this.source.empty;
}
}
}`);
static if (exactly || hasLength!R)
{
@property size_t length()
@property size_t length() const
{
return this.length_;
}
@ -97,18 +141,18 @@ private struct Take(R, bool exactly)
static if (isForwardRange!R)
{
typeof(this) save()
{
mixin(`typeof(this) save() ` ~ (hasConstSave!R ? `const ` : ``) ~
`{
return typeof(this)(this.source.save(), length);
}
}`);
}
static if (isRandomAccessRange!R)
{
@property auto ref back()
in (!empty)
mixin(`@property auto ref back() ` ~ (hasInoutBack!R ? `inout ` : ``) ~
`in (!empty)
{
return this.source[this.length - 1];
}
}`);
void popBack()
in (!empty)
@ -116,11 +160,11 @@ private struct Take(R, bool exactly)
--this.length_;
}
auto ref opIndex(size_t i)
in (i < length)
mixin(`auto ref opIndex(size_t i) ` ~ (hasInoutIndex!R ? `inout ` : ``) ~
`in (i < length)
{
return this.source[i];
}
}`);
static if (hasAssignableElements!R)
{
@ -152,12 +196,14 @@ private struct Take(R, bool exactly)
static if (!exactly && hasSlicing!R)
{
auto opSlice(size_t i, size_t j)
in (i <= j)
static if (is(typeof(length))) alias opDollar = length;
mixin(`auto opSlice(size_t i, size_t j) ` ~ (hasConstSlice!R ? `const ` : ``) ~
`in (i <= j)
in (j <= length)
{
return typeof(this)(this.source[i .. j], length);
}
}`);
}
version (unittest) static assert(isInputRange!Take);
@ -379,16 +425,16 @@ private struct Retro(Range)
this.source = source;
}
Retro save()
{
return this;
}
mixin(`Retro save() ` ~ (hasConstSave!Range ? `const ` : ``) ~
`{
return Retro(source.save());
}`);
@property auto ref front()
in (!empty)
mixin(`@property auto ref front() ` ~ (hasInoutBack!Range ? `inout ` : ``) ~
`in (!empty)
{
return this.source.back;
}
}`);
void popFront()
in (!empty)
@ -396,11 +442,11 @@ private struct Retro(Range)
this.source.popBack();
}
@property auto ref back()
in (!empty)
mixin(`@property auto ref back() ` ~ (hasInoutFront!Range ? `inout ` : ``) ~
`in (!empty)
{
return this.source.front;
}
}`);
void popBack()
in (!empty)
@ -408,38 +454,38 @@ private struct Retro(Range)
this.source.popFront();
}
@property bool empty()
{
mixin(`@property bool empty() ` ~ (hasConstEmpty!Range ? `const ` : ``) ~
`{
return this.source.empty;
}
}`);
static if (hasLength!Range)
{
@property size_t length()
{
mixin(`@property size_t length() ` ~ (hasConstLength!Range ? `const ` : ``) ~
`{
return this.source.length;
}
}`);
}
static if (isRandomAccessRange!Range && hasLength!Range)
{
auto ref opIndex(size_t i)
in (i < length)
mixin(`auto ref opIndex(size_t i) ` ~ (hasInoutIndex!Range ? `inout ` : ``) ~
`in (i < length)
{
return this.source[$ - ++i];
}
}`);
}
static if (hasLength!Range && hasSlicing!Range)
{
alias opDollar = length;
auto opSlice(size_t i, size_t j)
in (i <= j)
mixin(`auto opSlice(size_t i, size_t j) ` ~ (hasConstSlice!Range ? `const ` : ``) ~
`in (i <= j)
in (j <= length)
{
return typeof(this)(this.source[$-j .. $-i]);
}
}`);
}
static if (hasAssignableElements!Range)