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merge_without_buffer2.h
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merge_without_buffer2.h
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/*
* merge_without_buffer2.h
*
* Created on: Jan 2, 2020
* Author: Matthew Gregory Krupa
* Copyright: Metthew Gregory Krupa
*/
#ifndef SRC_MERGE_WITHOUT_BUFFER2_H_
#define SRC_MERGE_WITHOUT_BUFFER2_H_
#include <algorithm>
#include <functional>
//functional is included to allow for the use of std::less<>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <type_traits>
#include "merge_without_buffer_common.h"
/* EXAMPLE CALLS:
{
//One vector stores two sorted lists that are then merged into a single sorted vector.
//That is, after the call is finished, vec will be sorted.
int length_left = 8, length_right = 11;
std::vector<int> vec({ 1, 2, 3, 4, 4, 5, 9, 9, 0, 0, 1, 3, 5, 5, 6, 7, 9, 10, 10 });
auto start_left = vec.begin();
auto start_right = start_left + length_left;
auto one_past_end_right = vec.end();
//Default comparison is used
MergeWithOutBuffer2<std::vector<int>::iterator>(start_left,
start_right,
one_past_end_right);
//Custom comparison is used
auto comp = std::less<int>();
MergeWithOutBuffer2<std::vector<int>::iterator>(start_left,
start_right,
one_past_end_right,
comp);
}
{
//Two different sorted vectors are merged so that
// vec_left + vec_right becomes sorted. That is, after the call is finished,
// the last element of vec_left will be <= the first element of vec_right, and
// both vec_left and vec_right will be sorted.
std::vector<int> vec_left({ 1, 2, 3, 4, 4, 5, 9, 9 });
std::vector<int> vec_right({ 0, 0, 1, 3, 5, 5, 6, 7, 9, 10, 10 });
auto start_left = vec_left.begin();
auto one_past_end_left = vec_right.end();
auto start_right = vec_right.begin();
auto one_past_end_right = vec_right.end();
auto comp = std::less<int>();
//OPTION 1:
//Default comparison is used
MergeWithOutBuffer2<std::vector<int>::iterator>(start_left,
one_past_end_left,
start_right,
one_past_end_right);
//Custom comparison is used
MergeWithOutBuffer2<std::vector<int>::iterator>(start_left,
one_past_end_left,
start_right,
one_past_end_right,
comp);
//OPTION 2:
auto length_left = vec_left.size();
auto length_right = vec_right.size();
//Default comparison is used
MergeWithOutBuffer2<std::vector<int>::iterator>(start_left,
start_right,
one_past_end_right,
length_left,
length_right);
//Custom comparison is used
MergeWithOutBuffer2<std::vector<int>::iterator>(start_left,
start_right,
one_past_end_right,
length_left,
length_right,
comp);
}
*/
namespace merge_without_buffer_2_namespace {
//Assumes that:
// (1) length_left > 0 and length_right > 0, where
// length_left == std::distance(start_left, start_right) and
// length_right == std::distance(start_right, one_past_end)
// (2) comp(*start_right, *end_left), where end_left == start_right - 1
// (3) If is_left_trimmed == true then comp(*start_right, *start_left)
// (4) If is_left_trimmed == false then comp(*end_right, *end_left)
//
// Returns true if and only if the two non-decreasing sequences have been
// merged, in which case the values of start_left_out, start_right_out, and
// one_past_end_out would not have been changed.
//If this function returns false, then after execution finishes:
// (1) start_left_out (resp. start_right_out, one_past_end_out) would have
// been replaced by the local variable start_left (resp. start_right,
// one_past_end).
// (2) length_left_out > 1 and length_right_out > 1, and
// length_left_out == std::distance(start_left, start_right) and
// length_right_out == std::distance(start_right, one_past_end)
// (3) comp(*start_right, *end_left), where end_left == start_right - 1
// (4) comp(*start_right, *start_left)
// (5) comp(*end_left, *end_right)
// (6) comp(*start_left, *end_right)
// (7) comp(*(start_right + 1), *start_left), and
// (8) comp(*end_right, *(end_left - 1))
enum ThreeValue {
Unknown = -1,
False,
True
};
//In what follows, all assert()s would evaluate to true if they were to be
// called.
template<typename RandomAccessIterator, typename Compare,
typename Distance, typename CompareLessOrEqual, typename ValueType>
inline bool Trim2_switch_RAI(RandomAccessIterator &start_left_out,
RandomAccessIterator &start_right_out,
RandomAccessIterator &one_past_end_out,
Distance &length_left_out,
Distance &length_right_out,
Compare comp,
CompareLessOrEqual comp_le,
ThreeValue is_startleft_less_or_equal_to_startright,
ThreeValue is_startleft_less_or_equal_to_startright_plus1,
ThreeValue is_endleft_less_or_equal_to_endright,
ThreeValue is_endleft_minus1_less_or_equal_to_endright) {
auto start_left = start_left_out;
auto start_right = start_right_out;
auto one_past_end = one_past_end_out;
auto end_left = start_right - 1;
auto end_right = one_past_end - 1;
auto length_left = length_left_out;
auto length_right = length_right_out;
//Meaning of the following variables (using
// is_endleft_less_or_equal_to_endright as an example):
// (< 0) if (is_endleft_less_or_equal_to_endright < 0) then it is unknown
// whether or not comp_le(*end_left, *end_right) is true.
// (== 0) if (is_endleft_less_or_equal_to_endright == 0) then
// comp_le(*end_left, *end_right) is false.
// (> 0) if (is_endleft_less_or_equal_to_endright > 0) then
// comp_le(*end_left, *end_right) is true.
//The following are true:
//if (is_startleft_less_or_equal_to_startright >= 0) then
// is_startleft_less_or_equal_to_startright ==
// comp_le(*start_left, *start_right)
//if (is_startleft_less_or_equal_to_startright_plus1 >= 0) then
// length_right > 1 && is_startleft_less_or_equal_to_startright_plus1 ==
// comp_le(*start_left, *(start_right + 1))
//if (is_endleft_less_or_equal_to_endright >= 0) then
// is_endleft_less_or_equal_to_endright == comp_le(*end_left, *end_right)
//if (is_endleft_minus1_less_or_equal_to_endright >= 0) then
// length_left > 1 && is_endleft_minus1_less_or_equal_to_endright ==
// comp_le(*(end_left - 1), *end_right))
if (is_startleft_less_or_equal_to_startright < ThreeValue::False)
is_startleft_less_or_equal_to_startright =
static_cast<ThreeValue>(comp_le(*start_left, *start_right));
if (is_startleft_less_or_equal_to_startright < ThreeValue::False)
is_endleft_less_or_equal_to_endright =
static_cast<ThreeValue>(comp_le(*end_left, *end_right));
enum SwitchLabels {
startleft_le_startright = 0, //"le" stands for "less than or equal to"
endleft_le_endright,
startleft_le_startright_plus1,
endleft_minus1_le_endright,
length_dispatch,
length_left_less_than_length_right,
length_right_less_than_length_left,
length_left_equal_to_length_right,
trivial_case_length_left_equals_1,
trivial_case_length_right_equals_1,
trivial_case_endright_le_startleft
};
SwitchLabels jump_to = static_cast<SwitchLabels>(0);
while (true) {
//The following assert()s are true at this point:
//assert(length_left > 0 && length_right > 0);
//assert(comp(*start_right, *end_left));
switch (jump_to) {
case SwitchLabels::startleft_le_startright: {
if (is_startleft_less_or_equal_to_startright != 0) {
//The following are true at this point:
// assert(is_endleft_less_or_equal_to_endright == 0);
// if (is_startleft_less_or_equal_to_startright > 0)
// assert(comp_le(*start_left, *start_right));
if (is_startleft_less_or_equal_to_startright > 0 ||
comp_le(*start_left, *start_right)) {
// assert(length_left > 1);
mwob_namespace::TrimLeft1_RAI<RandomAccessIterator, Compare,
Distance, CompareLessOrEqual, ValueType>(
start_left, end_left, *start_right, length_left, comp, comp_le);
if (length_left <= 1) { //assert(false);
jump_to = SwitchLabels::trivial_case_length_left_equals_1;
continue ;
}
}
is_startleft_less_or_equal_to_startright = ThreeValue::False;
}
if (length_right <= 1) {
jump_to = SwitchLabels::trivial_case_length_right_equals_1;
continue ;
}
[[fallthrough]];
}
case SwitchLabels::endleft_le_endright: {
if (is_endleft_less_or_equal_to_endright != ThreeValue::False) {
//if (is_endleft_less_or_equal_to_endright > 0)
// assert(comp_le(*end_left, *end_right));
//assert(is_startleft_less_or_equal_to_startright == ThreeValue::False);
if (is_endleft_less_or_equal_to_endright > 0 ||
comp_le(*end_left, *end_right)) {
// assert(length_right > 1);
mwob_namespace::TrimRight1_RAI<RandomAccessIterator, Compare,
Distance, CompareLessOrEqual, ValueType>(
*end_left, start_right, end_right, one_past_end, length_right,
comp, comp_le);
if (length_right <= 1) {
jump_to = SwitchLabels::trivial_case_length_right_equals_1;
continue ;
}
}
is_endleft_less_or_equal_to_endright = ThreeValue::False;
} else { }
if (length_left <= 1) {
jump_to = SwitchLabels::trivial_case_length_left_equals_1;
continue ;
}
[[fallthrough]];
}
case SwitchLabels::startleft_le_startright_plus1: {
//assert(length_left > 1 && length_right > 1);
//assert(is_startleft_less_or_equal_to_startright == ThreeValue::False);
//assert(is_endleft_less_or_equal_to_endright == 0);
if (is_startleft_less_or_equal_to_startright_plus1 != 0) {
// if (is_startleft_less_or_equal_to_startright_plus1 > 0)
// assert(comp_le(*start_left, *start_right_plus1));
auto start_right_plus1 = start_right + 1;
if (is_startleft_less_or_equal_to_startright_plus1 > 0 ||
comp_le(*start_left, *start_right_plus1)) {
do {
std::iter_swap(start_left++, start_right);
} while(comp_le(*start_left, *start_right_plus1)) ;
length_left = std::distance(start_left, start_right);
if (length_left <= 1) {
jump_to = SwitchLabels::trivial_case_length_left_equals_1;
continue ;
}
// assert(comp(*start_right_plus1, *start_left));
}
is_startleft_less_or_equal_to_startright_plus1 = ThreeValue::False;
}
[[fallthrough]];
}
case SwitchLabels::endleft_minus1_le_endright: {
// assert(length_left > 1 && length_right > 1);
if (is_endleft_minus1_less_or_equal_to_endright != 0) {
auto end_left_minus1 = end_left - 1;
// if (is_endleft_minus1_less_or_equal_to_endright > 0)
// assert(comp_le(*end_left_minus1, *end_right));
if (is_endleft_minus1_less_or_equal_to_endright > 0 ||
comp_le(*end_left_minus1, *end_right)) {
do {
std::iter_swap(end_left, end_right--);
} while(comp_le(*end_left_minus1, *end_right)) ;
length_right = std::distance(start_right, end_right) + 1;
one_past_end = end_right + 1;
if (length_right <= 1) { //assert(false);
jump_to = SwitchLabels::trivial_case_length_right_equals_1;
continue ;
}
}
is_endleft_minus1_less_or_equal_to_endright = ThreeValue::False;
}
[[fallthrough]];
}
case SwitchLabels::length_dispatch: {
//assert(length_left > 1 && length_right > 1);
//assert(length_left == std::distance(start_left, end_left) + 1);
//assert(length_right == std::distance(start_right, end_right) + 1);
//assert(one_past_end == end_right + 1 && start_right == end_left + 1);
//assert(comp(*start_right, *start_left));
//assert(comp(*(start_right + 1), *start_left));
//assert(comp(*end_right, *(end_left - 1)));
//assert(std::is_sorted(start_left, start_right, comp));
//assert(std::is_sorted(start_right, one_past_end, comp));
//assert(is_startleft_less_or_equal_to_startright_plus1 ==
// comp_le(*start_left, *(start_right + 1)));
//assert(is_endleft_minus1_less_or_equal_to_endright ==
// comp_le(*(end_left - 1), *end_right));
if (length_left >= length_right) {
jump_to = static_cast<SwitchLabels>(
SwitchLabels::length_right_less_than_length_left
+ (length_left == length_right));
continue ;
}
[[fallthrough]];
}
case SwitchLabels::length_left_less_than_length_right: {
//assert(length_left < length_right);
RandomAccessIterator symmetric_point_right;
if (comp(*(symmetric_point_right = end_left + length_left), *start_left)) {
//assert(!comp_le(*(end_left - 1), *end_right));
bool is_left_length_less_than_right_length;
do {
//assert(length_left > 1 && length_right > 1);
std::swap_ranges(start_left, start_right, start_right);
start_left = start_right;
end_left = symmetric_point_right;
start_right = symmetric_point_right + 1;
length_right -= length_left;
//assert(length_left > 1 && end_left != start_left);
//assert(comp(*end_right, *end_left));
//assert(!comp_le(*(end_left - 1), *end_right));
//Note if length_right <= 1 then is_left_length_less_than_right_length
// below is false.
} while ((is_left_length_less_than_right_length = (length_left < length_right))
&& comp(*(symmetric_point_right = end_left + length_left), *start_left));
is_startleft_less_or_equal_to_startright_plus1 = ThreeValue::Unknown;
is_startleft_less_or_equal_to_startright
= static_cast<ThreeValue>(comp_le(*start_left, *start_right));
//assert(length_left > 1 && end_left != start_left);
//assert(!comp_le(*end_left, *end_right));
//assert(!comp_le(*(end_left - 1), *end_right));
//assert(comp(*start_right, *end_left));
if (is_startleft_less_or_equal_to_startright) {
jump_to = SwitchLabels::startleft_le_startright;
continue ;
} else if (length_right <= 1) {
jump_to = SwitchLabels::trivial_case_length_right_equals_1;
continue ;
} else if (comp_le(*end_right, *start_left)) {
jump_to = SwitchLabels::trivial_case_endright_le_startleft;
continue ;
} else if ((is_startleft_less_or_equal_to_startright_plus1 =
static_cast<ThreeValue>(comp_le(*start_left, *(start_right + 1))))) {
jump_to = SwitchLabels::startleft_le_startright_plus1;
continue ;
} else if (!is_left_length_less_than_right_length) {
//assert(length_left >= length_right);
jump_to = static_cast<SwitchLabels>(
SwitchLabels::length_right_less_than_length_left
+ (length_left == length_right));
continue ;
}
//assert(comp(*end_right, *(end_left - 1)));
}
assert(start_right != end_right && start_right != one_past_end);
break ;
}
case SwitchLabels::length_right_less_than_length_left: {
//assert(length_left > length_right && length_right > 0);
//assert(start_right == end_left + 1);
RandomAccessIterator symmetric_point_left;
if (comp(*end_right, *(symmetric_point_left = start_right - length_right))) {
bool is_right_length_less_than_left;
do {
//assert(length_left > 1 && length_right > 1);
//assert(one_past_end == end_right + 1);
std::swap_ranges(start_right, one_past_end, symmetric_point_left);
one_past_end = start_right;
end_right = one_past_end - 1;
start_right = symmetric_point_left; //= end_left + 1;
//assert((end_left - length_right) == symmetric_point_left - 1);
end_left = symmetric_point_left - 1;
length_left -= length_right;
//assert(length_left > 0 && length_right > 1);
//assert(comp(*start_right, *start_left));
//assert(start_right != end_right && start_right != one_past_end);
//assert(!comp_le(*start_left, *(start_right + 1)));
//Note: if length_left <= 1 then is_right_less_than_left below
// is false.
} while ((is_right_length_less_than_left = (length_left > length_right)) &&
comp(*end_right, *(symmetric_point_left = start_right - length_right)));
is_endleft_minus1_less_or_equal_to_endright = ThreeValue::Unknown;
is_endleft_less_or_equal_to_endright
= static_cast<ThreeValue>(comp_le(*end_left, *end_right));
//assert(length_right > 1);
//assert(start_right != end_right && start_right != one_past_end);
//assert(!comp_le(*start_left, *start_right));
//assert(!comp_le(*start_left, *(start_right + 1)));
//assert(comp(*start_right, *end_left));
if (is_endleft_less_or_equal_to_endright) {
jump_to = SwitchLabels::endleft_le_endright;
continue ;
} else if (length_left <= 1) {
jump_to = SwitchLabels::trivial_case_length_left_equals_1;
continue ;
} else if (comp_le(*end_right, *start_left)) {
jump_to = SwitchLabels::trivial_case_endright_le_startleft;
continue ;
} else if ((is_endleft_minus1_less_or_equal_to_endright =
static_cast<ThreeValue>(comp_le(*(end_left - 1), *end_right)))) {
jump_to = SwitchLabels::endleft_minus1_le_endright;
continue ;
} else if (!is_right_length_less_than_left) {
//assert(length_left <= length_right);
//assert(!comp_le(*end_right, *start_left));
jump_to = static_cast<SwitchLabels>(
SwitchLabels::length_left_less_than_length_right
+ (2 * static_cast<unsigned char>(length_left == length_right)));
continue ;
}
//assert(comp(*(start_right + 1), *start_left));
}
break ;
}
case SwitchLabels::length_left_equal_to_length_right: {
//assert(length_left == length_right);
if (comp_le(*end_right, *start_left)) {
jump_to = SwitchLabels::trivial_case_endright_le_startleft;
continue ;
}
break ;
}
case SwitchLabels::trivial_case_length_left_equals_1: {
//assert(length_left == 1 && start_left == end_left);
//assert(start_left != start_right && start_right != one_past_end);
if (length_right == 1) {
std::iter_swap(start_left, start_right);
} else {
mwob_namespace::RotateLeftBy1<RandomAccessIterator, Distance>(
start_left, one_past_end);
}
//assert(std::is_sorted(start_left, one_past_end, comp));
return true;
}
case SwitchLabels::trivial_case_length_right_equals_1: {
//assert(length_right == 1 && start_right == end_right);
mwob_namespace::RotateRightBy1<RandomAccessIterator, Distance>(
start_left, end_right, length_left);
//assert(std::is_sorted(start_left, one_past_end, comp));
return true;
}
case SwitchLabels::trivial_case_endright_le_startleft: {
if (comp(*end_right, *start_left)) {
std::rotate(start_left, start_right, one_past_end);
//assert(std::is_sorted(start_left, one_past_end, comp));
return true;
}
//At this point:
// (1) comp_le(*start_left, *end_right)
// (2) comp_le(*end_right, *start_left)
// so in particular, *start_left and *end_right are equivalent
// under comp().
// (3) comp(*start_right, *start_left)
// (4) comp(*end_right, *end_left)
// (5) start_left != end_left (or equivalently, length_left > 1)
// (6) start_right != end_right (or equivalently, length_right > 1)
// These imply that:
// (A) comp(*start_right, *end_left)
// (B) comp(*start_left, *end_right)
//assert(length_right > 1 && length_left > 1);
//assert(start_right != end_right && start_left != end_left);
//assert(comp_le(*end_right, *start_left));
//assert(comp_le(*start_left, *end_right));
//assert(comp(*start_left, *end_left));
//assert(comp(*start_right, *end_right));
auto first_greater_than = mwob_namespace::SmallestIteratorGreaterThan_KnownToExist_RAI<
RandomAccessIterator, Compare, Distance, CompareLessOrEqual, ValueType>(
start_left + 1, end_left, start_right, *start_left, comp, comp_le,
false //check_start_iterator_each_iteration
);
auto num_const_left = std::distance(start_left, first_greater_than);
auto last_less_than = mwob_namespace::LargestIteratorLessThan_KnownToExist_RAI<
RandomAccessIterator, Compare, Distance, CompareLessOrEqual, ValueType>(
start_right, end_right - 1, end_right, *start_left, comp, comp_le,
false //check_end_iterator_each_iteration
);
auto num_const_right = std::distance(last_less_than, end_right);
//In this comment, let end_right_value = *end_right and let
// start_left_value = *start_left. Note that
// comp_le(end_right_value, start_left_value) and
// comp_le(start_left_value, end_right_value) (i.e. start_left_value
// and end_right_value are equivalent under comp).
//
//After the following std::rotate() is executed, the value end_right_value
// will be to the LEFT of the value start_left_value, which means that
// the merge would not be stable. We correct this by performing another
// std::rotate of all values that are equivalent to end_right_value
auto location_of_old_start_left
= std::rotate(start_left, start_right, one_past_end);
//assert(std::is_sorted(start_left, one_past_end, comp));
std::rotate(location_of_old_start_left - num_const_right,
//leftmost value is equivalent to end_right_value
location_of_old_start_left,
location_of_old_start_left + num_const_left); //one past
//rightmost value equivalent to end_right_value
//assert(std::is_sorted(start_left, one_past_end, comp));
return true;
}
} //End switch()
break ;
} //END while (true)
//assert(start_right == end_left + 1);
//assert(length_left == std::distance(start_left, end_left) + 1);
//assert(length_right == std::distance(start_right, end_right) + 1);
//assert(length_left > 1 && length_right > 1);
//assert(comp(*end_right, *(end_left - 1)));
//assert(comp(*(start_right + 1), *start_left));
start_left_out = start_left;
start_right_out = start_right;
one_past_end_out = end_right + 1;
length_left_out = length_left;
length_right_out = length_right;
return false; //The two non-decreasing sequences are not yet merged.
}
//This is Trim2 designed for Bidirectional Iterators.
//Since computing std::distance() is potentially expensive, we keep track
// of length_left and length_right.
//
//In what follows, all assert()s would evaluate to true if they were to be
// called.
//Due to the similarity between Trim2_switch_bi() and Trim2_switch_RAI(),
// assert()s and comments that appear in Trim2_switch_RAI() and
// would be repeated in Trim2_switch_bi() are instead omitted
// from Trim2_switch_bi().
template<typename BidirectionalIterator, typename Compare,
typename Distance, typename CompareLessOrEqual, typename ValueType>
inline bool Trim2_switch_bi(BidirectionalIterator &start_left_out,
BidirectionalIterator &start_right_out,
BidirectionalIterator &one_past_end_out,
Distance &length_left_out,
Distance &length_right_out,
Distance &d_out,
BidirectionalIterator &start_2nd_quarter_out,
BidirectionalIterator &start_4th_quarter_out,
Compare comp,
CompareLessOrEqual comp_le,
ThreeValue is_startleft_less_or_equal_to_startright,
ThreeValue is_startleft_less_or_equal_to_startright_plus1,
ThreeValue is_endleft_less_or_equal_to_endright,
ThreeValue is_endleft_minus1_less_or_equal_to_endright) {
auto start_left = start_left_out;
auto start_right = start_right_out;
auto one_past_end = one_past_end_out;
auto end_left = start_right;
(void)--end_left;
auto end_right = one_past_end;
(void)--end_right;
auto length_left = length_left_out;
auto length_right = length_right_out;
auto start_right_plus1 = start_right;
(void)++start_right_plus1;
auto end_left_minus1 = end_left;
(void)--end_left_minus1;
if (is_startleft_less_or_equal_to_startright < ThreeValue::False)
is_startleft_less_or_equal_to_startright
= static_cast<ThreeValue>(comp_le(*start_left, *start_right));
if (is_endleft_less_or_equal_to_endright < ThreeValue::False)
is_endleft_less_or_equal_to_endright
= static_cast<ThreeValue>(comp_le(*end_left, *end_right));
enum SwitchLabels {
startleft_le_startright = 0,
endleft_le_endright,
startleft_le_startright_plus1,
endleft_minus1_le_endright,
length_dispatch,
length_left_less_than_length_right,
length_right_less_than_length_left,
length_left_equal_to_length_right,
trivial_case_length_left_equals_1,
trivial_case_length_right_equals_1,
trivial_case_endright_le_startleft
};
BidirectionalIterator symmetric_point_left, symmetric_point_right;
Distance distance_to_symmetric_point;
SwitchLabels jump_to = static_cast<SwitchLabels>(0);
while (true) {
switch (jump_to) {
case SwitchLabels::startleft_le_startright: {
if (is_startleft_less_or_equal_to_startright != 0) {
if (is_startleft_less_or_equal_to_startright > 0 ||
comp_le(*start_left, *start_right)) {
mwob_namespace::TrimLeft1_bi<BidirectionalIterator, Compare,
Distance, CompareLessOrEqual, ValueType>(start_left, end_left,
start_right, length_left, comp, comp_le, true);
if (length_left <= 1) {
jump_to = SwitchLabels::trivial_case_length_left_equals_1;
continue ;
}
}
}
is_startleft_less_or_equal_to_startright = ThreeValue::False;
if (length_right <= 1) {
jump_to = SwitchLabels::trivial_case_length_right_equals_1;
continue ;
}
}
[[fallthrough]];
case SwitchLabels::endleft_le_endright: {
if (is_endleft_less_or_equal_to_endright != ThreeValue::False) {
if (is_endleft_less_or_equal_to_endright > 0 ||
comp_le(*end_left, *end_right)) {
mwob_namespace::TrimRight1_bi<BidirectionalIterator, Compare,
Distance, CompareLessOrEqual, ValueType>(*end_left, start_right,
end_right, one_past_end, length_right, comp, comp_le, true);
start_right_plus1 = start_right;
(void)++start_right_plus1;
if (length_right <= 1) {
jump_to = SwitchLabels::trivial_case_length_right_equals_1;
continue ;
}
}
}
is_endleft_less_or_equal_to_endright = ThreeValue::False;
if (length_left <= 1) {
jump_to = SwitchLabels::trivial_case_length_left_equals_1;
continue ;
}
}
[[fallthrough]];
case SwitchLabels::startleft_le_startright_plus1: {
if (is_startleft_less_or_equal_to_startright_plus1 != 0) {
start_right_plus1 = start_right;
(void)++start_right_plus1;
if (is_startleft_less_or_equal_to_startright_plus1 > 0 ||
comp_le(*start_left, *start_right_plus1)) {
do {
std::iter_swap(start_left++, start_right);
--length_left;
} while(comp_le(*start_left, *start_right_plus1)) ;
if (length_left <= 1) {
jump_to = SwitchLabels::trivial_case_length_left_equals_1;
continue ;
}
is_startleft_less_or_equal_to_startright_plus1 = ThreeValue::False;
}
}
}
[[fallthrough]];
case SwitchLabels::endleft_minus1_le_endright: {
if (is_endleft_minus1_less_or_equal_to_endright != 0) {
end_left_minus1 = end_left;
(void)--end_left_minus1;
if (is_endleft_minus1_less_or_equal_to_endright > 0 ||
comp_le(*end_left_minus1, *end_right)) {
do {
std::iter_swap(end_left, end_right--);
--length_right;
} while(comp_le(*end_left_minus1, *end_right)) ;
one_past_end = end_right;
(void)++one_past_end;
if (length_right <= 1) {
jump_to = SwitchLabels::trivial_case_length_right_equals_1;
continue ;
}
}
is_endleft_minus1_less_or_equal_to_endright = ThreeValue::False;
}
}
[[fallthrough]];
case SwitchLabels::length_dispatch: {
//assert(end_left_minus1 == end_left - 1);
if (length_left >= length_right) {
jump_to = static_cast<SwitchLabels>(
SwitchLabels::length_right_less_than_length_left
+ (length_left == length_right));
continue ;
}
[[fallthrough]];
}
case SwitchLabels::length_left_less_than_length_right: {
symmetric_point_right = end_left;
std::advance(symmetric_point_right, length_left);
if (comp(*symmetric_point_right, *start_left)) {
bool is_left_length_less_than_right_length;
do {
std::swap_ranges(start_left, start_right, start_right);
start_left = start_right;
end_left = symmetric_point_right;
start_right = symmetric_point_right;
(void)++start_right;
start_right_plus1 = start_right;
(void)++start_right_plus1;
length_right -= length_left;
if (!(is_left_length_less_than_right_length
= (length_left < length_right)))
break ;
symmetric_point_right = end_left;
std::advance(symmetric_point_right, length_left);
} while (comp(*symmetric_point_right, *start_left));
is_startleft_less_or_equal_to_startright_plus1 = ThreeValue::Unknown;
is_startleft_less_or_equal_to_startright
= static_cast<ThreeValue>(comp_le(*start_left, *start_right));
end_left_minus1 = end_left;
(void)--end_left_minus1;
bool is_length_right_less_or_equal_to_1 = (length_right <= 1);
if (!is_length_right_less_or_equal_to_1) {
start_right_plus1 = start_right;
(void)++start_right_plus1;
}
if (is_startleft_less_or_equal_to_startright) {
jump_to = SwitchLabels::startleft_le_startright;
continue ;
} else if (length_right <= 1) {
jump_to = SwitchLabels::trivial_case_length_right_equals_1;
continue ;
} else if (comp_le(*end_right, *start_left)) {
jump_to = SwitchLabels::trivial_case_endright_le_startleft;
continue ;
} else if ((is_startleft_less_or_equal_to_startright_plus1 =
static_cast<ThreeValue>(comp_le(*start_left, *start_right_plus1)))) {
jump_to = SwitchLabels::startleft_le_startright_plus1;
continue ;
} else if (!is_left_length_less_than_right_length) {
jump_to = static_cast<SwitchLabels>(
SwitchLabels::length_right_less_than_length_left
+ (length_left == length_right));
continue ;
}
}
symmetric_point_left = start_left;
distance_to_symmetric_point = length_left;
break ;
}
case SwitchLabels::length_right_less_than_length_left: {
symmetric_point_left = start_right;
std::advance(symmetric_point_left, - length_right);
if (comp(*end_right, *symmetric_point_left)) {
bool is_right_length_less_than_left;
do {
std::swap_ranges(start_right, one_past_end, symmetric_point_left);
one_past_end = start_right;
end_right = one_past_end;
(void)--end_right;
start_right = symmetric_point_left; //= end_left + 1;
end_left = symmetric_point_left;
(void)--end_left;
length_left -= length_right;
start_right_plus1 = start_right;
(void)++start_right_plus1;
if (!(is_right_length_less_than_left = (length_left > length_right)))
break ;
symmetric_point_left = start_right;
std::advance(symmetric_point_left, - length_right);
distance_to_symmetric_point = length_right;
//assert(std::distance(symmetric_point_left, end_left) ==
// std::distance(start_right, end_right));
} while (comp(*end_right, *symmetric_point_left));
is_endleft_minus1_less_or_equal_to_endright = ThreeValue::Unknown;
is_endleft_less_or_equal_to_endright
= static_cast<ThreeValue>(comp_le(*end_left, *end_right));
bool is_length_left_less_or_equal_to_1 = (length_left <= 1);
if (!is_length_left_less_or_equal_to_1) {
end_left_minus1 = end_left;
(void)--end_left_minus1;
}
start_right_plus1 = start_right;
(void)++start_right_plus1;
if (is_endleft_less_or_equal_to_endright) {
jump_to = SwitchLabels::endleft_le_endright;
continue ;
} else if (length_left <= 1) {
jump_to = SwitchLabels::trivial_case_length_left_equals_1;
continue ;
} else if (comp_le(*end_right, *start_left)) {
jump_to = SwitchLabels::trivial_case_endright_le_startleft;
continue ;
} else if ((is_endleft_minus1_less_or_equal_to_endright =
static_cast<ThreeValue>(comp_le(*end_left_minus1, *end_right)))) {
jump_to = SwitchLabels::endleft_minus1_le_endright;
continue ;
} else if (!is_right_length_less_than_left) {
jump_to = static_cast<SwitchLabels>(
SwitchLabels::length_left_less_than_length_right
+ (2 * static_cast<unsigned char>(length_left == length_right)));
continue ;
}
}
symmetric_point_right = end_right;
distance_to_symmetric_point = length_right;
break ;
}
case SwitchLabels::length_left_equal_to_length_right: {
if (comp_le(*end_right, *start_left)) {
jump_to = SwitchLabels::trivial_case_endright_le_startleft;
continue ;
}
symmetric_point_left = start_left;
symmetric_point_right = end_right;
distance_to_symmetric_point = length_left;
break ;
}
case SwitchLabels::trivial_case_length_left_equals_1: {
if (length_right == 1) {
std::iter_swap(start_left, start_right);
} else {
mwob_namespace::RotateLeftBy1<BidirectionalIterator, Distance>(
start_left, one_past_end);
}
return true;
}
case SwitchLabels::trivial_case_length_right_equals_1: {
mwob_namespace::RotateRightBy1<BidirectionalIterator, Distance>(
start_left, end_right, length_left);
return true;
}
case SwitchLabels::trivial_case_endright_le_startleft: {
if (comp(*end_right, *start_left)) {
std::rotate(start_left, start_right, one_past_end);
return true;
}
Distance distance_from_start_it_to_first_greater_than;
// auto first_greater_than =
mwob_namespace::SmallestIteratorGreaterThan_KnownToExist_bi<
BidirectionalIterator, Compare, Distance, CompareLessOrEqual, ValueType>(
start_left, end_left, start_right, length_left, *start_left,
distance_from_start_it_to_first_greater_than,
comp, comp_le
);
//assert(distance_from_start_it_to_first_greater_than ==
// std::distance(start_left, first_greater_than));
auto num_const_left = distance_from_start_it_to_first_greater_than;
Distance distance_from_end_right_to_last_less_than;
// auto last_less_than =
mwob_namespace::LargestIteratorLessThan_KnownToExist_bi<
BidirectionalIterator, Compare, Distance, CompareLessOrEqual, ValueType>(
start_right, end_right, one_past_end, length_right, *start_left,
distance_from_end_right_to_last_less_than,
comp, comp_le
);
//auto distance_from_start_it_to_last_less_than = length_right
// - distance_from_end_right_to_last_less_than;
//assert(distance_from_end_right_to_last_less_than ==
// std::distance(last_less_than, end_right));
auto num_const_right = distance_from_end_right_to_last_less_than;
auto location_of_old_start_left
= std::rotate(start_left, start_right, one_past_end);
auto left_most_value = location_of_old_start_left;
std::advance(left_most_value, - num_const_right);
auto one_past_right_most_value = location_of_old_start_left;
std::advance(one_past_right_most_value, num_const_left);
std::rotate(left_most_value,
location_of_old_start_left,
one_past_right_most_value);
return true;
} //End case
} //End switch()
break ;
} //END while (true)
//one_past_end = end_right;
//(void)++one_past_end;
//assert(one_past_end == end_right + 1);
//assert(comp(*start_right, *end_left));
//assert(std::distance(symmetric_point_left, end_left) ==
// std::distance(start_right, symmetric_point_right));
//assert(distance_to_symmetric_point ==
// std::distance(symmetric_point_left, start_right));
//assert(distance_to_symmetric_point >= 2);
//assert(comp_le(*symmetric_point_left, *symmetric_point_right));
//We will now find the SMALLEST integer
// 1 <= d < distance_to_symmetric_point such that
// *(end_left - d) <= *(start_right + d)
Distance d;
//We will then define start_2nd_quarter and start_4th_quarter by:
// start_2nd_quarter = start_right - d;
// start_4th_quarter = start_right + d;
BidirectionalIterator start_2nd_quarter, start_4th_quarter;
{
Distance d_min = 1, d_max = distance_to_symmetric_point - 1;
//assert(start_left != end_left && start_right != end_right);
BidirectionalIterator left_it_min = end_left, right_it_min = start_right;
(void)--left_it_min;
(void)++right_it_min;
start_2nd_quarter = symmetric_point_left;
start_4th_quarter = symmetric_point_right;
while (d_min < d_max) {
//assert(d_min == std::distance(start_right, right_it_min));
//assert(d_min == std::distance(left_it_min, end_left));
//assert(d_max == std::distance(start_2nd_quarter, end_left));
//assert(d_max == std::distance(start_right, start_4th_quarter));
auto half_distance = (d_max - d_min) / 2;
auto next_left_it = left_it_min;
auto next_right_it = right_it_min;
std::advance(next_left_it, - half_distance);
std::advance(next_right_it, half_distance);
if (comp_le(*next_left_it, *next_right_it)) {
d_max = d_min + half_distance;
start_2nd_quarter = next_left_it;
start_4th_quarter = next_right_it;
} else { // else *next_right_it < *next_left_it
d_min += half_distance + 1;
//assert(d_min <= d_max);
//assert(next_left_it != start_left && next_right_it != end_right);
left_it_min = next_left_it;
right_it_min = next_right_it;
(void)--left_it_min;
(void)++right_it_min;
}
}
//assert(d_min == d_max && d_min > 0);
d = d_min;
//assert(comp_le(*start_2nd_quarter, *start_4th_quarter));
//assert(start_2nd_quarter != end_left && start_4th_quarter != start_right);
//assert(!comp_le(*(start_2nd_quarter + 1), *start_4th_quarter_minus1));
//assert(comp(*(start_4th_quarter - 1), *start_2nd_quarter_plus1));
}
//assert(one_past_end == end_right + 1 && start_right == end_left + 1);
//assert(length_left == std::distance(start_left, end_left) + 1);
//assert(length_right == std::distance(start_right, end_right) + 1);
//assert(comp(*end_right, *(end_left - 1)));
//assert(comp(*(start_right + 1), *start_left));
start_left_out = start_left;
start_right_out = start_right;
one_past_end_out = one_past_end;
d_out = d;
start_2nd_quarter_out = ++start_2nd_quarter;;
start_4th_quarter_out = start_4th_quarter;
length_left_out = length_left;
length_right_out = length_right;
return false; //The two non-decreasing sequences are not yet merged.
}
//Assumes that:
// (1) length_left > 0 and length_right > 0, where
// length_left == std::distance(start_left, start_right) and
// length_right == std::distance(start_right, one_past_end)
// (2) comp(*start_right, *end_left) where end_left == start_right - 1
// (3) If is_left_trimmed == true then comp(*start_right, *start_left)
// (4) If is_left_trimmed == false then comp(*end_right, *end_left)
template<typename RandomAccessIterator, typename Compare,
typename Distance, typename CompareLessOrEqual, typename ValueType>
void MergeWithOutBuffer2_recursive_RAI(RandomAccessIterator start_left,
RandomAccessIterator start_right,
RandomAccessIterator one_past_end,
Distance length_left,
Distance length_right,
Compare comp,
CompareLessOrEqual comp_le,
ThreeValue is_startleft_less_or_equal_to_startright,
ThreeValue is_startleft_less_or_equal_to_startright_plus1,
ThreeValue is_endleft_less_or_equal_to_endright,
ThreeValue is_endleft_minus1_less_or_equal_to_endright) {
//assert(length_left > 0 && length_right > 0);
//assert(comp(*start_right, *(start_right - 1)));
//if (is_startleft_less_or_equal_to_startright >= 0)
// assert(is_startleft_less_or_equal_to_startright ==
// comp_le(*start_left, *start_right));
//if (is_startleft_less_or_equal_to_startright_plus1 >= 0)
// assert(length_right > 1 && is_startleft_less_or_equal_to_startright_plus1
// == comp_le(*start_left, *start_right + 1));
//if (is_endleft_less_or_equal_to_endright >= 0)
// assert(is_endleft_less_or_equal_to_endright ==
// comp_le(*end_left, *end_right));
//if (is_endleft_minus1_less_or_equal_to_endright >= 0)
// assert(length_left > 1 && is_endleft_minus1_less_or_equal_to_endright ==
// comp_le(*(end_left - 1), *end_right));
if (Trim2_switch_RAI<RandomAccessIterator, Compare, Distance,
CompareLessOrEqual, ValueType>(start_left, start_right,
one_past_end, length_left, length_right, comp,
comp_le, is_startleft_less_or_equal_to_startright,
is_startleft_less_or_equal_to_startright_plus1,
is_endleft_less_or_equal_to_endright,