36 lines
1.1 KiB
D
36 lines
1.1 KiB
D
import std.stdio, std.typecons;
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auto hashJoin(size_t index1, size_t index2, T1, T2)
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(in T1[] table1, in T2[] table2) pure /*nothrow*/ @safe
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if (is(typeof(T1.init[index1]) == typeof(T2.init[index2]))) {
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// Hash phase.
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T1[][typeof(T1.init[index1])] h;
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foreach (const s; table1)
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h[s[index1]] ~= s;
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// Join phase.
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Tuple!(const T1, const T2)[] result;
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foreach (const r; table2)
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foreach (const s; h.get(r[index2], null)) // Not nothrow.
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result ~= tuple(s, r);
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return result;
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}
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void main() {
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alias T = tuple;
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immutable table1 = [T(27, "Jonah"),
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T(18, "Alan"),
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T(28, "Glory"),
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T(18, "Popeye"),
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T(28, "Alan")];
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immutable table2 = [T("Jonah", "Whales"),
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T("Jonah", "Spiders"),
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T("Alan", "Ghosts"),
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T("Alan", "Zombies"),
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T("Glory", "Buffy")];
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foreach (const row; hashJoin!(1, 0)(table1, table2))
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writefln("(%s, %5s) (%5s, %7s)", row[0][], row[1][]);
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}
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