From cd9960db2ab3cdf9434fc5caf954d25aea484108 Mon Sep 17 00:00:00 2001 From: Eugen Wissner Date: Sun, 25 Mar 2018 08:17:38 +0200 Subject: [PATCH] Add take range adapter --- source/tanya/range/package.d | 284 +++++++++++++++++++++++++++++++++++ 1 file changed, 284 insertions(+) diff --git a/source/tanya/range/package.d b/source/tanya/range/package.d index 8894c95..1d03e22 100644 --- a/source/tanya/range/package.d +++ b/source/tanya/range/package.d @@ -15,5 +15,289 @@ */ module tanya.range; +import tanya.algorithm.mutation; +import tanya.math; public import tanya.range.array; 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); +}