real::detail::anchored_walk_bill Struct Reference

Tells when the anchored walks from candidates should give way to one forward pass and one reverse, from what the walks that found no match cost against the distance crossed. More...

#include <pike.hpp>

Public Member Functions
constexpr bool	overspent (std::size_t length, std::size_t crossed)
	Bills one walk that found no match, and tells whether the walks should give way.

Public Attributes
std::size_t	walks {0}
	Walks that found no match.
std::size_t	read {0}
	Bytes those walks read.

Static Public Attributes
static constexpr std::size_t	per_walk {16}
	One walk that found nothing, doubled with the rest.
static constexpr std::size_t	per_walk_byte {2}
	One byte such a walk read.
static constexpr std::size_t	per_pass_byte {3}
	One byte crossed: the bound of 1.5, doubled.
static constexpr std::size_t	slack {64}
	About four walks before any verdict: a batch of spans starts a fresh bill, and the gap each side is wide.

Detailed Description

Tells when the anchored walks from candidates should give way to one forward pass and one reverse, from what the walks that found no match cost against the distance crossed.

A failing walk inside a run of candidate bytes rereads the run the previous one crossed. Score: 8 * failed walks + bytes read, per byte crossed. Over 20 pattern/subject pairs the walks won at <= 0.43 and lost (up to 6x) at >= 4.65, nothing between; the bound sits at 1.5. Namespace-scoped so its verdicts are tested without a search.

Member Function Documentation

overspent()

constexpr bool real::detail::anchored_walk_bill::overspent ( std::size_t  length, std::size_t  crossed  )

inlineconstexpr

Bills one walk that found no match, and tells whether the walks should give way.

Parameters

[in]	length	Bytes the walk read.
[in]	crossed	Bytes from where the walks began to the walk's candidate.

Returns

True once the single pass would clearly cost less.

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The documentation for this struct was generated from the following file:

• include/real/engine/pike.hpp