SearchPolicy

Policy used with the searching primitives lowerBound, upperBound, and equalRange of SortedRange below.

Values

Value	Meaning
linear	Searches in a linear fashion.
trot	Searches with a step that is grows linearly (1, 2, 3,...) leading to a quadratic search schedule (indexes tried are 0, 1, 3, 6, 10, 15, 21, 28,...) Once the search overshoots its target, the remaining interval is searched using binary search. The search is completed in O(sqrt(n)) time. Use it when you are reasonably confident that the value is around the beginning of the range.
gallop	Performs a galloping search algorithm, i.e. searches with a step that doubles every time, (1, 2, 4, 8, ...) leading to an exponential search schedule (indexes tried are 0, 1, 3, 7, 15, 31, 63,...) Once the search overshoots its target, the remaining interval is searched using binary search. A value is found in O(log(n)) time.
binarySearch	Searches using a classic interval halving policy. The search starts in the middle of the range, and each search step cuts the range in half. This policy finds a value in O(log(n)) time but is less cache friendly than `gallop` for large ranges. The `binarySearch` policy is used as the last step of `trot`, `gallop`, `trotBackwards`, and `gallopBackwards` strategies.
trotBackwards	Similar to `trot` but starts backwards. Use it when confident that the value is around the end of the range.
gallopBackwards	Similar to `gallop` but starts backwards. Use it when confident that the value is around the end of the range.

Examples

import std.algorithm.comparison : equal;

auto a = assumeSorted([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
auto p1 = a.upperBound!(SearchPolicy.binarySearch)(3);
assert(p1.equal([4, 5, 6, 7, 8, 9]));

auto p2 = a.lowerBound!(SearchPolicy.gallop)(4);
assert(p2.equal([0, 1, 2, 3]));

The OpenD Programming Language

SearchPolicy

Values

Examples

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