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ae9287c4f3
closes https://github.com/nim-lang/RFCs/issues/554 Adds a symmetric difference operation to the language bitset type. This maps to a simple `xor` operation on the backend and thus is likely faster than the current alternatives, namely `(a - b) + (b - a)` or `a + b - a * b`. The compiler VM implementation of bitsets already implemented this via `symdiffSets` but it was never used. The standalone binary operation is added to `setutils`, named `symmetricDifference` in line with [hash sets](https://nim-lang.org/docs/sets.html#symmetricDifference%2CHashSet%5BA%5D%2CHashSet%5BA%5D). An operator version `-+-` and an in-place version like `toggle` as described in the RFC are also added, implemented as trivial sugar.
70 lines
1.8 KiB
Nim
70 lines
1.8 KiB
Nim
discard """
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matrix: "--mm:refc; --mm:orc"
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targets: "c js"
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"""
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import std/setutils
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import std/assertions
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type
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Colors = enum
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red, green = 5, blue = 10
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Bar = enum
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bar0 = -1, bar1, bar2
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template main =
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block: # toSet
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doAssert "abcbb".toSet == {'a', 'b', 'c'}
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doAssert toSet([10u8, 12, 13]) == {10u8, 12, 13}
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doAssert toSet(0u16..30) == {0u16..30}
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type A = distinct char
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doAssert [A('x')].toSet == {A('x')}
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block: # fullSet
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doAssert fullSet(Colors) == {red, green, blue}
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doAssert fullSet(char) == {0.chr..255.chr}
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doAssert fullSet(Bar) == {bar0, bar1, bar2}
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doAssert fullSet(bool) == {true, false}
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block: # complement
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doAssert {red, blue}.complement == {green}
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doAssert (complement {red, green, blue}).card == 0
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doAssert (complement {false}) == {true}
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doAssert {bar0}.complement == {bar1, bar2}
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doAssert {range[0..10](0), 1, 2, 3}.complement == {range[0..10](4), 5, 6, 7, 8, 9, 10}
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doAssert {'0'..'9'}.complement == {0.char..255.char} - {'0'..'9'}
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block: # `[]=`
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type A = enum
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a0, a1, a2, a3
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var s = {a0, a3}
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s[a0] = false
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s[a1] = false
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doAssert s == {a3}
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s[a2] = true
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s[a3] = true
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doAssert s == {a2, a3}
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block: # set symmetric difference (xor), https://github.com/nim-lang/RFCs/issues/554
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type T = set[range[0..15]]
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let x: T = {1, 4, 5, 8, 9}
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let y: T = {0, 2..6, 9}
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let res = symmetricDifference(x, y)
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doAssert res == {0, 1, 2, 3, 6, 8}
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doAssert res == (x + y - x * y)
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doAssert res == ((x - y) + (y - x))
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var z = x
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doAssert z == {1, 4, 5, 8, 9}
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doAssert z == x
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z.toggle(y)
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doAssert z == res
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z.toggle(y)
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doAssert z == x
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z.toggle({1, 5})
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doAssert z == {4, 8, 9}
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z.toggle({3, 8})
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doAssert z == {3, 4, 9}
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main()
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static: main()
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