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Remove uses of reverse_iterator in diff implementation

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This commit is contained in:
Maxime Coste 2020-02-18 20:20:09 +11:00
parent 329f291ae0
commit 401ef84a4b
2 changed files with 22 additions and 18 deletions
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21
src/diff.hh
View File

@ -5,11 +5,8 @@
// "An O(ND) Difference Algorithm and Its Variations"
// (http://xmailserver.org/diff2.pdf)
#include "array_view.hh"
#include <algorithm>
#include <functional>
#include <iterator>
#include <memory>
namespace Kakoune
@ -24,7 +21,7 @@ struct Snake
enum Op { Add, Del, RevAdd, RevDel } op;
};
template<typename IteratorA, typename IteratorB, typename Equal>
template<bool forward, typename IteratorA, typename IteratorB, typename Equal>
Snake find_end_snake_of_further_reaching_dpath(IteratorA a, int N, IteratorB b, int M,
const int* V, const int D, const int k, Equal eq)
{
@ -37,9 +34,13 @@ Snake find_end_snake_of_further_reaching_dpath(IteratorA a, int N, IteratorB b,
// we are by construction on diagonal k, so our position along b (y) is x - k.
const int y = x - k;
auto at = [](auto&& base, int index, int size) -> decltype(auto) {
return forward ? base[index] : base[size - 1 - index];
};
int u = x, v = y;
// follow end snake along diagonal k
while (u < N and v < M and eq(a[u], b[v]))
while (u < N and v < M and eq(at(a, u, N), at(b, v, M)))
++u, ++v;
return { x, y, u, v, add ? Snake::Add : Snake::Del };
@ -53,14 +54,12 @@ Snake find_middle_snake(IteratorA a, int N, IteratorB b, int M,
V1[1] = 0;
V2[1] = 0;
std::reverse_iterator<IteratorA> ra{a + N};
std::reverse_iterator<IteratorB> rb{b + M};
const int max_D = std::min((M + N + 1) / 2 + 1, cost_limit);
for (int D = 0; D < max_D; ++D)
{
for (int k1 = -D; k1 <= D; k1 += 2)
{
auto p = find_end_snake_of_further_reaching_dpath(a, N, b, M, V1, D, k1, eq);
auto p = find_end_snake_of_further_reaching_dpath<true>(a, N, b, M, V1, D, k1, eq);
V1[k1] = p.u;
const int k2 = -(k1 - delta);
@ -70,7 +69,7 @@ Snake find_middle_snake(IteratorA a, int N, IteratorB b, int M,
for (int k2 = -D; k2 <= D; k2 += 2)
{
auto p = find_end_snake_of_further_reaching_dpath(ra, N, rb, M, V2, D, k2, eq);
auto p = find_end_snake_of_further_reaching_dpath<false>(a, N, b, M, V2, D, k2, eq);
V2[k2] = p.u;
const int k1 = -(k2 - delta);
@ -85,14 +84,14 @@ Snake find_middle_snake(IteratorA a, int N, IteratorB b, int M,
auto score = [](const Snake& s) { return s.u + s.v; };
for (int k1 = -max_D; k1 <= max_D; k1 += 2)
{
auto p = find_end_snake_of_further_reaching_dpath(a, N, b, M, V1, max_D, k1, eq);
auto p = find_end_snake_of_further_reaching_dpath<true>(a, N, b, M, V1, max_D, k1, eq);
V1[k1] = p.u;
if ((delta % 2 != 0) and p.u <= N and p.v <= M and score(p) >= score(best))
best = p;
}
for (int k2 = -max_D; k2 <= max_D; k2 += 2)
{
auto p = find_end_snake_of_further_reaching_dpath(ra, N, rb, M, V2, max_D, k2, eq);
auto p = find_end_snake_of_further_reaching_dpath<false>(a, N, b, M, V2, max_D, k2, eq);
V2[k2] = p.u;
if ((delta % 2 == 0) and p.u <= N and p.v <= M and score(p) >= score(best))
best = {p.x, p.y, p.u, p.v, (Snake::Op)(p.op + Snake::RevAdd)};

19
src/unit_tests.cc
View File

@ -17,7 +17,7 @@ UnitTest test_utf8{[]()
UnitTest test_diff{[]()
{
struct Diff{DiffOp op; int len; int posB;};
struct Diff{DiffOp op; int len; int posB = 0;};
auto check_diff = [](StringView a, StringView b, std::initializer_list<Diff> diffs) {
size_t count = 0;
for_each_diff(a.begin(), (int)a.length(), b.begin(), (int)b.length(),
@ -28,14 +28,19 @@ UnitTest test_diff{[]()
});
kak_assert(count == diffs.size());
};
check_diff("a?", "!", {{DiffOp::Remove, 1, 0}, {DiffOp::Add, 1, 0}, {DiffOp::Remove, 1, 0}});
check_diff("abcde", "cd", {{DiffOp::Remove, 2, 0}, {DiffOp::Keep, 2, 0}, {DiffOp::Remove, 1, 0}});
check_diff("abcd", "cdef", {{DiffOp::Remove, 2, 0}, {DiffOp::Keep, 2, 0}, {DiffOp::Add, 2, 2}});
check_diff("a?", "!", {{DiffOp::Remove, 1}, {DiffOp::Add, 1}, {DiffOp::Remove, 1}});
check_diff("abcde", "cd", {{DiffOp::Remove, 2}, {DiffOp::Keep, 2}, {DiffOp::Remove, 1}});
check_diff("abcd", "cdef", {{DiffOp::Remove, 2}, {DiffOp::Keep, 2}, {DiffOp::Add, 2, 2}});
check_diff("mais que fais la police", "mais ou va la police",
{{DiffOp::Keep, 5, 0}, {DiffOp::Remove, 1, 0}, {DiffOp::Add, 1, 5}, {DiffOp::Keep, 1, 0},
{DiffOp::Remove, 1, 0}, {DiffOp::Keep, 1, 0}, {DiffOp::Add, 1, 8}, {DiffOp::Remove, 1, 0},
{DiffOp::Keep, 1, 0}, {DiffOp::Remove, 2, 0}, {DiffOp::Keep, 10, 0}} );
{{DiffOp::Keep, 5}, {DiffOp::Remove, 1}, {DiffOp::Add, 1, 5}, {DiffOp::Keep, 1},
{DiffOp::Remove, 1}, {DiffOp::Keep, 1}, {DiffOp::Add, 1, 8}, {DiffOp::Remove, 1},
{DiffOp::Keep, 1}, {DiffOp::Remove, 2}, {DiffOp::Keep, 10}} );
check_diff("abcdefghijk", "1cdef2hij34",
{{DiffOp::Remove, 2}, {DiffOp::Add, 1, 0}, {DiffOp::Keep, 4}, {DiffOp::Remove, 1},
{DiffOp::Add, 1, 5}, {DiffOp::Keep, 3}, {DiffOp::Add, 2, 9}, {DiffOp::Remove, 1}});
}};
UnitTest* UnitTest::list = nullptr;