146 lines
2.6 KiB
D
146 lines
2.6 KiB
D
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// Copyright Brian Schott (Sir Alaran) 2012.
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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module circularbuffer;
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import std.math;
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import std.array;
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import std.range;
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struct CircularBuffer(T, R) if (isInputRange!(R) && is (ElementType!(R) == T))
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{
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public:
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this (size_t size, R range)
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{
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this.range = range;
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this.margin = size;
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data = new T[(margin * 2) + 1];
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if (range.empty())
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{
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_empty = true;
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return;
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}
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for (size_t i = 0; i <= margin && !this.range.empty(); ++i)
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{
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data[i] = this.range.front();
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this.range.popFront();
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end++;
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}
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}
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T opIndex(size_t index) const
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in
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{
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assert (index <= sourceIndex + margin);
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assert (index >= sourceIndex - margin);
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}
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body
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{
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return data[index % data.length];
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}
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T front() const @property
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{
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return data[index];
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}
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T peek(int offset)
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in
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{
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assert(abs(offset) <= margin);
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assert(sourceIndex + offset >= 0);
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}
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body
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{
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return data[(index + offset) % data.length];
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}
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T popFront()
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in
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{
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assert (!_empty);
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}
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body
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{
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T v = data[index];
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index = (index + 1) % data.length;
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++sourceIndex;
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if (range.empty())
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{
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if (index == end)
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_empty = true;
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}
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else
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{
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data[end] = range.front();
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end = (end + 1) % data.length;
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range.popFront();
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}
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return v;
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}
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bool empty() const @property
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{
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return _empty;
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}
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private:
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R range;
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immutable size_t margin;
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T[] data;
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size_t sourceIndex;
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size_t end;
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size_t index;
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bool _empty;
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}
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unittest
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{
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int[] items = [1, 2];
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auto buf = CircularBuffer!(int, int[])(5, items);
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auto result = array(buf);
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assert(result == items);
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}
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unittest
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{
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int[] arr = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
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auto buf = CircularBuffer!(int, int[])(2, arr);
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assert (buf.data.length == 5);
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auto iterated = array(buf);
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assert (iterated == arr);
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}
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unittest
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{
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int[] arr = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
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auto buf = CircularBuffer!(int, int[])(2, arr);
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buf.popFront();
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buf.popFront();
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buf.popFront();
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buf.popFront();
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assert (buf.front == 4);
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assert (buf[2] == 2);
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assert (buf[6] == 6);
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}
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unittest
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{
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int[] arr = [0, 1, 2, 3];
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auto buf = CircularBuffer!(int, int[])(2, arr);
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assert (buf.peek(0) == 0);
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assert (buf.peek(1) == 1);
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assert (buf.peek(2) == 2);
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buf.popFront();
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buf.popFront();
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assert (buf.peek(-2) == 0);
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assert (buf.peek(-1) == 1);
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assert (buf.peek(0) == 2);
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assert (buf.peek(1) == 3);
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}
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