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mapping: add dst2src and src2dst

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Signed-off-by: Simon Rozman <simon@rozman.si>
This commit is contained in:
Simon Rozman 2024-04-25 12:41:08 +02:00
parent a97b037a78
commit c6c7498562
1 changed files with 165 additions and 0 deletions
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165
include/stdex/mapping.hpp
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@ -6,6 +6,7 @@
#pragma once
#include "compat.hpp"
#include <algorithm>
#include <vector>
namespace stdex
@ -71,4 +72,168 @@ namespace stdex
template <class T, class AX = std::allocator<mapping<T>>>
using mapping_vector = std::vector<mapping<T>, AX>;
///
/// Transforms destination index to source index
///
/// \param[in] mapping Ordered vector of source to destination mappings
/// \param[in] to Index in destination string
///
/// \returns Index in source string
///
template <class T, class AX = std::allocator<mapping<T>>>
T dst2src(_In_ const std::vector<stdex::mapping<T>, AX>& mapping, _In_ T to)
{
if (mapping.empty())
return to;
for (size_t l = 0, r = mapping.size();;) {
if (l < r) {
auto m = (l + r) / 2;
const auto& el = mapping[m];
if (to < el.to) r = m;
else if (el.to < to) l = m + 1;
else return el.from;
}
else if (l) {
const auto& el = mapping[l - 1];
return el.from + (to - el.to);
}
else {
const auto& el = mapping[0];
return std::min<T>(to, el.from);
}
}
}
///
/// Transforms destination index to source index
///
/// \param[in] mapping Ordered vector of source to destination mappings
/// \param[in] to Index in destination string
/// \param[in,out] m Hint to speed-up bisection when calling this function in a loop and successive destination string indexes are in vicinity. Initialize to 0.
///
/// \returns Index in source string
///
template <class T, class AX = std::allocator<mapping<T>>>
T dst2src(_In_ const std::vector<stdex::mapping<T>, AX>& mapping, _In_ T to, _Inout_opt_ size_t& m)
{
if (mapping.empty())
return to;
size_t l, r;
const auto& el = mapping[m];
if (to < el.to) {
l = 0;
r = m;
}
else if (el.to < to) {
if (mapping.size() - 1 <= m || to < mapping[m + 1].to)
return el.from + (to - el.to);
l = m + 1;
r = mapping.size();
}
else
return el.from;
for (;;) {
if (l < r) {
m = (l + r) / 2;
const auto& el = mapping[m];
if (to < el.to) r = m;
else if (el.to < to) l = m + 1;
else return el.from;
}
else if (l) {
const auto& el = mapping[m = l - 1];
return el.from + (to - el.to);
}
else {
const auto& el = mapping[m = 0];
return std::min<T>(to, el.from);
}
}
}
///
/// Transforms source index to destination index
///
/// \param[in] mapping Ordered vector of source to destination mappings
/// \param[in] from Index in source string
///
/// \returns Index in destination string
///
template <class T, class AX = std::allocator<mapping<T>>>
T src2dst(_In_ const std::vector<stdex::mapping<T>, AX>& mapping, _In_ T from)
{
if (mapping.empty())
return from;
for (size_t l = 0, r = mapping.size();;) {
if (l < r) {
auto m = (l + r) / 2;
const auto& el = mapping[m];
if (from < el.from) r = m;
else if (el.from < from) l = m + 1;
else return el.to;
}
else if (l) {
const auto& el = mapping[l - 1];
return el.to + (from - el.from);
}
else {
const auto& el = mapping[0];
return std::min<T>(from, el.to);
}
}
}
///
/// Transforms source index to destination index
///
/// \param[in] mapping Ordered vector of source to destination mappings
/// \param[in] from Index in source string
/// \param[in,out] m Hint to speed-up bisection when calling this function in a loop and successive source string indexes are in vicinity. Initialize to 0.
///
/// \returns Index in destination string
///
template <class T, class AX = std::allocator<mapping<T>>>
T src2dst(_In_ const std::vector<stdex::mapping<T>, AX>& mapping, _In_ T from, _Inout_opt_ size_t& m)
{
if (mapping.empty())
return from;
size_t l, r;
const auto& el = mapping[m];
if (from < el.from) {
l = 0;
r = m;
}
else if (el.from < from) {
if (mapping.size() - 1 <= m || from < mapping[m + 1].from)
return el.to + (from - el.from);
l = m + 1;
r = mapping.size();
}
else
return el.to;
for (;;) {
if (l < r) {
m = (l + r) / 2;
const auto& el = mapping[m];
if (from < el.from) r = m;
else if (el.from < from) l = m + 1;
else return el.to;
}
else if (l) {
const auto& el = mapping[m = l - 1];
return el.to + (from - el.from);
}
else {
const auto& el = mapping[m = 0];
return std::min<T>(from, el.to);
}
}
}
}