From 1110808a9d39d4b808aef724c861a2e1a38d2a69 Mon Sep 17 00:00:00 2001
From: Devtools Arcadia <arcadia-devtools@yandex-team.ru>
Date: Mon, 7 Feb 2022 18:08:42 +0300
Subject: intermediate changes ref:cde9a383711a11544ce7e107a78147fb96cc4029

---
 library/cpp/diff/diff.cpp | 87 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 87 insertions(+)
 create mode 100644 library/cpp/diff/diff.cpp

(limited to 'library/cpp/diff/diff.cpp')

diff --git a/library/cpp/diff/diff.cpp b/library/cpp/diff/diff.cpp
new file mode 100644
index 00000000000..be57da7f396
--- /dev/null
+++ b/library/cpp/diff/diff.cpp
@@ -0,0 +1,87 @@
+#include "diff.h"
+
+#include <util/generic/hash.h>
+#include <util/digest/fnv.h>
+
+#include <iterator>
+
+template <typename T>
+struct TCollectionImpl {
+    TVector<TConstArrayRef<T>> Words;
+    TVector<ui64> Keys;
+
+    inline bool Consume(const T* b, const T* e, const T*) {
+        if (b < e) {
+            Words.push_back(TConstArrayRef<T>(b, e));
+            Keys.push_back(FnvHash<ui64>((const char*)b, (e - b) * sizeof(T)));
+        }
+        return true;
+    }
+
+    TConstArrayRef<T> Remap(const TConstArrayRef<ui64>& keys) const {
+        if (keys.empty()) {
+            return TConstArrayRef<T>();
+        }
+        auto firstWordPos = std::distance(Keys.data(), keys.begin());
+        auto lastWordPos = std::distance(Keys.data(), keys.end()) - 1;
+        Y_ASSERT(firstWordPos >= 0);
+        Y_ASSERT(lastWordPos >= firstWordPos);
+        Y_ASSERT(static_cast<size_t>(lastWordPos) < Words.size());
+
+        return TConstArrayRef<T>(Words[firstWordPos].begin(), Words[lastWordPos].end());
+    }
+
+    TConstArrayRef<ui64> GetKeys() const {
+        return TConstArrayRef<ui64>(Keys);
+    }
+};
+
+template <typename T>
+struct TCollection {
+};
+
+template <>
+struct TCollection<char>: public TCollectionImpl<char> {
+    TCollection(const TStringBuf& str, const TString& delims) {
+        TSetDelimiter<const char> set(delims.data());
+        TKeepDelimiters<TCollection<char>> c(this);
+        SplitString(str.begin(), str.end(), set, c);
+    }
+};
+
+template <>
+struct TCollection<wchar16>: public TCollectionImpl<wchar16> {
+    TCollection(const TWtringBuf& str, const TUtf16String& delims) {
+        TSetDelimiter<const wchar16> set(delims.data());
+        TKeepDelimiters<TCollection<wchar16>> c(this);
+        SplitString(str.begin(), str.end(), set, c);
+    }
+};
+
+size_t NDiff::InlineDiff(TVector<TChunk<char>>& chunks, const TStringBuf& left, const TStringBuf& right, const TString& delims) {
+    if (delims.empty()) {
+        return InlineDiff<char>(chunks, TConstArrayRef<char>(left.data(), left.size()), TConstArrayRef<char>(right.data(), right.size()));
+    }
+    TCollection<char> c1(left, delims);
+    TCollection<char> c2(right, delims);
+    TVector<TChunk<ui64>> diff;
+    const size_t dist = InlineDiff<ui64>(diff, c1.GetKeys(), c2.GetKeys());
+    for (const auto& it : diff) {
+        chunks.push_back(TChunk<char>(c1.Remap(it.Left), c2.Remap(it.Right), c1.Remap(it.Common)));
+    }
+    return dist;
+}
+
+size_t NDiff::InlineDiff(TVector<TChunk<wchar16>>& chunks, const TWtringBuf& left, const TWtringBuf& right, const TUtf16String& delims) {
+    if (delims.empty()) {
+        return InlineDiff<wchar16>(chunks, TConstArrayRef<wchar16>(left.data(), left.size()), TConstArrayRef<wchar16>(right.data(), right.size()));
+    }
+    TCollection<wchar16> c1(left, delims);
+    TCollection<wchar16> c2(right, delims);
+    TVector<TChunk<ui64>> diff;
+    const size_t dist = InlineDiff<ui64>(diff, c1.GetKeys(), c2.GetKeys());
+    for (const auto& it : diff) {
+        chunks.push_back(TChunk<wchar16>(c1.Remap(it.Left), c2.Remap(it.Right), c1.Remap(it.Common)));
+    }
+    return dist;
+}
-- 
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