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Enum std.range.TransverseOptions

Options for the FrontTransversal and Transversal ranges (below).

enum TransverseOptions : int { ... }

Enum members

assumeJagged When transversed, the elements of a range of ranges are assumed to have different lengths (e.g. a jagged array).
assumeNotJagged The transversal assumes, without verifying, that the elements of a range of ranges have all the same length. This option is useful if checking was already done from the outside of the range.
enforceNotJagged The transversal enforces that the elements of a range of ranges have all the same length (e.g. an array of arrays, all having the same length). Checking is done once upon construction of the transversal range.


import std.algorithm.comparison : equal;
import std.exception : assertThrown;

auto arr = [[1, 2], [3, 4, 5]];

auto r1 = arr.frontTransversal!(TransverseOptions.assumeJagged);
assert(r1.equal([1, 3]));

// throws on construction

auto r2 = arr.frontTransversal!(TransverseOptions.assumeNotJagged);
assert(r2.equal([1, 3]));

// either assuming or checking for equal lengths makes
// the result a random access range
writeln(r2[0]); // 1
static assert(!__traits(compiles, r1[0]));


Andrei Alexandrescu, David Simcha, Jonathan M Davis, and Jack Stouffer. Credit for some of the ideas in building this module goes to Leonardo Maffi.


Boost License 1.0.