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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include <cstddef>
#include <cstdint>
#include <functional>
#include <vector>
namespace search {
namespace detail {
template <typename T>
concept FoldableString = std::same_as<const char*,T> || std::same_as<std::reference_wrapper<const std::vector<uint32_t>>, T>;
}
class FoldedStringCompare
{
public:
/**
* count number of UCS-4 characters in UTF-8 string
*
* @param key NUL terminated UTF-8 string
* @return integer number of symbols in UTF-8 string before NUL
*/
static size_t size(const char *key);
/**
* Compare UTF-8 key with UTF-8 other key after folding both
*
* @param key NUL terminated UTF-8 string or vector<uint32_t>
* @param okey NUL terminated UTF-8 string or vector<uint32_t>
* @return integer -1 if key < okey, 0 if key == okey, 1 if key > okey
**/
template <bool fold_lhs, bool fold_rhs, detail::FoldableString KeyType, detail::FoldableString OKeyType>
static int compareFolded(KeyType key, OKeyType okey);
/**
* Compare UTF-8 key with UTF-8 other key after folding both.
*
* @param key NUL terminated UTF-8 string
* @param okey NUL terminated UTF-8 string
* @param prefixLen max number of symbols to compare before
* considering keys identical.
*
* @return integer -1 if key < okey, 0 if key == okey, 1 if key > okey
*/
template <bool fold_lhs, bool fold_rhs>
static int compareFoldedPrefix(const char *key, const char *okey, size_t prefixLen);
/*
* Compare UTF-8 key with UTF-8 other key after folding both, if
* they seem equal then fall back to comparing without folding.
*
* @param key NUL terminated UTF-8 string
* @param okey NUL terminated UTF-8 string
* @return integer -1 if key < okey, 0 if key == okey, 1 if key > okey
*/
static int compare(const char *key, const char *okey);
/*
* Compare UTF-8 key with UTF-8 other key after folding both for prefix, if
* they seem equal then fall back to comparing without folding.
*
* @param key NUL terminated UTF-8 string
* @param okey NUL terminated UTF-8 string
* @param prefixLen max number of symbols to compare before
* considering keys identical.
* @return integer -1 if key < okey, 0 if key == okey, 1 if key > okey
*/
static int comparePrefix(const char *key, const char *okey, size_t prefixLen);
};
} // namespace search
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