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// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
#include "arrow/array/diff.h"
#include <algorithm>
#include <functional>
#include <limits>
#include <memory>
#include <string>
#include <utility>
#include <vector>
#include "arrow/array.h"
#include "arrow/buffer.h"
#include "arrow/buffer_builder.h"
#include "arrow/memory_pool.h"
#include "arrow/pretty_print.h"
#include "arrow/status.h"
#include "arrow/type_traits.h"
#include "arrow/util/logging.h"
#include "arrow/util/range.h"
#include "arrow/util/string.h"
#include "arrow/util/variant.h"
#include "arrow/util/visibility.h"
#include "arrow/vendored/datetime.h"
#include "arrow/visitor_inline.h"
namespace arrow {
using internal::checked_cast;
using internal::checked_pointer_cast;
using internal::MakeLazyRange;
template <typename ArrayType>
auto GetView(const ArrayType& array, int64_t index) -> decltype(array.GetView(index)) {
return array.GetView(index);
}
struct Slice {
const Array* array_;
int64_t offset_, length_;
bool operator==(const Slice& other) const {
return length_ == other.length_ &&
array_->RangeEquals(offset_, offset_ + length_, other.offset_, *other.array_);
}
bool operator!=(const Slice& other) const { return !(*this == other); }
};
template <typename ArrayType, typename T = typename ArrayType::TypeClass,
typename = enable_if_list_like<T>>
static Slice GetView(const ArrayType& array, int64_t index) {
return Slice{array.values().get(), array.value_offset(index),
array.value_length(index)};
}
struct UnitSlice {
const Array* array_;
int64_t offset_;
bool operator==(const UnitSlice& other) const {
return array_->RangeEquals(offset_, offset_ + 1, other.offset_, *other.array_);
}
bool operator!=(const UnitSlice& other) const { return !(*this == other); }
};
// FIXME(bkietz) this is inefficient;
// StructArray's fields can be diffed independently then merged
static UnitSlice GetView(const StructArray& array, int64_t index) {
return UnitSlice{&array, index};
}
static UnitSlice GetView(const UnionArray& array, int64_t index) {
return UnitSlice{&array, index};
}
struct NullTag {
constexpr bool operator==(const NullTag& other) const { return true; }
constexpr bool operator!=(const NullTag& other) const { return false; }
};
template <typename T>
class NullOr {
public:
using VariantType = util::variant<NullTag, T>;
NullOr() : variant_(NullTag{}) {}
explicit NullOr(T t) : variant_(std::move(t)) {}
template <typename ArrayType>
NullOr(const ArrayType& array, int64_t index) {
if (array.IsNull(index)) {
variant_.emplace(NullTag{});
} else {
variant_.emplace(GetView(array, index));
}
}
bool operator==(const NullOr& other) const { return variant_ == other.variant_; }
bool operator!=(const NullOr& other) const { return variant_ != other.variant_; }
private:
VariantType variant_;
};
template <typename ArrayType>
using ViewType = decltype(GetView(std::declval<ArrayType>(), 0));
template <typename ArrayType>
class ViewGenerator {
public:
using View = ViewType<ArrayType>;
explicit ViewGenerator(const Array& array)
: array_(checked_cast<const ArrayType&>(array)) {
DCHECK_EQ(array.null_count(), 0);
}
View operator()(int64_t index) const { return GetView(array_, index); }
private:
const ArrayType& array_;
};
template <typename ArrayType>
internal::LazyRange<ViewGenerator<ArrayType>> MakeViewRange(const Array& array) {
using Generator = ViewGenerator<ArrayType>;
return internal::LazyRange<Generator>(Generator(array), array.length());
}
template <typename ArrayType>
class NullOrViewGenerator {
public:
using View = ViewType<ArrayType>;
explicit NullOrViewGenerator(const Array& array)
: array_(checked_cast<const ArrayType&>(array)) {}
NullOr<View> operator()(int64_t index) const {
return array_.IsNull(index) ? NullOr<View>() : NullOr<View>(GetView(array_, index));
}
private:
const ArrayType& array_;
};
template <typename ArrayType>
internal::LazyRange<NullOrViewGenerator<ArrayType>> MakeNullOrViewRange(
const Array& array) {
using Generator = NullOrViewGenerator<ArrayType>;
return internal::LazyRange<Generator>(Generator(array), array.length());
}
/// A generic sequence difference algorithm, based on
///
/// E. W. Myers, "An O(ND) difference algorithm and its variations,"
/// Algorithmica, vol. 1, no. 1-4, pp. 251–266, 1986.
///
/// To summarize, an edit script is computed by maintaining the furthest set of EditPoints
/// which are reachable in a given number of edits D. This is used to compute the furthest
/// set reachable with D+1 edits, and the process continues inductively until a complete
/// edit script is discovered.
///
/// From each edit point a single deletion and insertion is made then as many shared
/// elements as possible are skipped, recording only the endpoint of the run. This
/// representation is minimal in the common case where the sequences differ only slightly,
/// since most of the elements are shared between base and target and are represented
/// implicitly.
template <typename Iterator>
class QuadraticSpaceMyersDiff {
public:
// represents an intermediate state in the comparison of two arrays
struct EditPoint {
Iterator base, target;
bool operator==(EditPoint other) const {
return base == other.base && other.target;
}
};
// increment the position within base (the element pointed to was deleted)
// then extend maximally
EditPoint DeleteOne(EditPoint p) const {
if (p.base != base_end_) {
++p.base;
}
return ExtendFrom(p);
}
// increment the position within target (the element pointed to was inserted)
// then extend maximally
EditPoint InsertOne(EditPoint p) const {
if (p.target != target_end_) {
++p.target;
}
return ExtendFrom(p);
}
// increment the position within base and target (the elements skipped in this way were
// present in both sequences)
EditPoint ExtendFrom(EditPoint p) const {
for (; p.base != base_end_ && p.target != target_end_; ++p.base, ++p.target) {
if (*p.base != *p.target) {
break;
}
}
return p;
}
QuadraticSpaceMyersDiff(Iterator base_begin, Iterator base_end, Iterator target_begin,
Iterator target_end)
: base_begin_(base_begin),
base_end_(base_end),
target_begin_(target_begin),
target_end_(target_end),
endpoint_base_({ExtendFrom({base_begin_, target_begin_}).base}),
insert_({true}) {
if (std::distance(base_begin_, base_end_) ==
std::distance(target_begin_, target_end_) &&
endpoint_base_[0] == base_end_) {
// trivial case: base == target
finish_index_ = 0;
}
}
// beginning of a range for storing per-edit state in endpoint_base_ and insert_
int64_t StorageOffset(int64_t edit_count) const {
return edit_count * (edit_count + 1) / 2;
}
// given edit_count and index, augment endpoint_base_[index] with the corresponding
// position in target (which is only implicitly represented in edit_count, index)
EditPoint GetEditPoint(int64_t edit_count, int64_t index) const {
DCHECK_GE(index, StorageOffset(edit_count));
DCHECK_LT(index, StorageOffset(edit_count + 1));
auto insertions_minus_deletions =
2 * (index - StorageOffset(edit_count)) - edit_count;
auto maximal_base = endpoint_base_[index];
auto maximal_target = std::min(
target_begin_ + ((maximal_base - base_begin_) + insertions_minus_deletions),
target_end_);
return {maximal_base, maximal_target};
}
void Next() {
++edit_count_;
// base_begin_ is used as a dummy value here since Iterator may not be default
// constructible. The newly allocated range is completely overwritten below.
endpoint_base_.resize(StorageOffset(edit_count_ + 1), base_begin_);
insert_.resize(StorageOffset(edit_count_ + 1), false);
auto previous_offset = StorageOffset(edit_count_ - 1);
auto current_offset = StorageOffset(edit_count_);
// try deleting from base first
for (int64_t i = 0, i_out = 0; i < edit_count_; ++i, ++i_out) {
auto previous_endpoint = GetEditPoint(edit_count_ - 1, i + previous_offset);
endpoint_base_[i_out + current_offset] = DeleteOne(previous_endpoint).base;
}
// check if inserting from target could do better
for (int64_t i = 0, i_out = 1; i < edit_count_; ++i, ++i_out) {
// retrieve the previously computed best endpoint for (edit_count_, i_out)
// for comparison with the best endpoint achievable with an insertion
auto endpoint_after_deletion = GetEditPoint(edit_count_, i_out + current_offset);
auto previous_endpoint = GetEditPoint(edit_count_ - 1, i + previous_offset);
auto endpoint_after_insertion = InsertOne(previous_endpoint);
if (endpoint_after_insertion.base - endpoint_after_deletion.base >= 0) {
// insertion was more efficient; keep it and mark the insertion in insert_
insert_[i_out + current_offset] = true;
endpoint_base_[i_out + current_offset] = endpoint_after_insertion.base;
}
}
// check for completion
EditPoint finish = {base_end_, target_end_};
for (int64_t i_out = 0; i_out < edit_count_ + 1; ++i_out) {
if (GetEditPoint(edit_count_, i_out + current_offset) == finish) {
finish_index_ = i_out + current_offset;
return;
}
}
}
bool Done() { return finish_index_ != -1; }
Result<std::shared_ptr<StructArray>> GetEdits(MemoryPool* pool) {
DCHECK(Done());
int64_t length = edit_count_ + 1;
std::shared_ptr<Buffer> insert_buf, run_length_buf;
RETURN_NOT_OK(AllocateEmptyBitmap(pool, length, &insert_buf));
RETURN_NOT_OK(AllocateBuffer(pool, length * sizeof(int64_t), &run_length_buf));
auto run_length = reinterpret_cast<int64_t*>(run_length_buf->mutable_data());
auto index = finish_index_;
auto endpoint = GetEditPoint(edit_count_, finish_index_);
for (int64_t i = edit_count_; i > 0; --i) {
bool insert = insert_[index];
BitUtil::SetBitTo(insert_buf->mutable_data(), i, insert);
auto insertions_minus_deletions =
(endpoint.base - base_begin_) - (endpoint.target - target_begin_);
if (insert) {
++insertions_minus_deletions;
} else {
--insertions_minus_deletions;
}
index = (i - 1 - insertions_minus_deletions) / 2 + StorageOffset(i - 1);
// endpoint of previous edit
auto previous = GetEditPoint(i - 1, index);
run_length[i] = endpoint.base - previous.base - !insert;
DCHECK_GE(run_length[i], 0);
endpoint = previous;
}
BitUtil::SetBitTo(insert_buf->mutable_data(), 0, false);
run_length[0] = endpoint.base - base_begin_;
return StructArray::Make({std::make_shared<BooleanArray>(length, insert_buf),
std::make_shared<Int64Array>(length, run_length_buf)},
{field("insert", boolean()), field("run_length", int64())});
}
private:
int64_t finish_index_ = -1;
int64_t edit_count_ = 0;
Iterator base_begin_, base_end_;
Iterator target_begin_, target_end_;
// each element of endpoint_base_ is the furthest position in base reachable given an
// edit_count and (# insertions) - (# deletions). Each bit of insert_ records whether
// the corresponding furthest position was reached via an insertion or a deletion
// (followed by a run of shared elements). See StorageOffset for the
// layout of these vectors
std::vector<Iterator> endpoint_base_;
std::vector<bool> insert_;
};
struct DiffImpl {
Status Visit(const NullType&) {
bool insert = base_.length() < target_.length();
auto run_length = std::min(base_.length(), target_.length());
auto edit_count = std::max(base_.length(), target_.length()) - run_length;
TypedBufferBuilder<bool> insert_builder(pool_);
RETURN_NOT_OK(insert_builder.Resize(edit_count + 1));
insert_builder.UnsafeAppend(false);
TypedBufferBuilder<int64_t> run_length_builder(pool_);
RETURN_NOT_OK(run_length_builder.Resize(edit_count + 1));
run_length_builder.UnsafeAppend(run_length);
if (edit_count > 0) {
insert_builder.UnsafeAppend(edit_count, insert);
run_length_builder.UnsafeAppend(edit_count, 0);
}
std::shared_ptr<Buffer> insert_buf, run_length_buf;
RETURN_NOT_OK(insert_builder.Finish(&insert_buf));
RETURN_NOT_OK(run_length_builder.Finish(&run_length_buf));
ARROW_ASSIGN_OR_RAISE(
out_,
StructArray::Make({std::make_shared<BooleanArray>(edit_count + 1, insert_buf),
std::make_shared<Int64Array>(edit_count + 1, run_length_buf)},
{field("insert", boolean()), field("run_length", int64())}));
return Status::OK();
}
template <typename T>
Status Visit(const T&) {
using ArrayType = typename TypeTraits<T>::ArrayType;
if (base_.null_count() == 0 && target_.null_count() == 0) {
auto base = MakeViewRange<ArrayType>(base_);
auto>
ARROW_ASSIGN_OR_RAISE(out_,
Diff(base.begin(), base.end(), target.begin(), target.end()));
} else {
auto base = MakeNullOrViewRange<ArrayType>(base_);
auto>
ARROW_ASSIGN_OR_RAISE(out_,
Diff(base.begin(), base.end(), target.begin(), target.end()));
}
return Status::OK();
}
Status Visit(const ExtensionType&) {
auto base = checked_cast<const ExtensionArray&>(base_).storage();
auto class="pl-k">const ExtensionArray&>(target_).storage();
ARROW_ASSIGN_OR_RAISE(out_, arrow::Diff(*base, *target, pool_));
return Status::OK();
}
Status Visit(const DictionaryType& t) {
return Status::NotImplemented("diffing arrays of type ", t);
}
Result<std::shared_ptr<StructArray>> Diff() {
RETURN_NOT_OK(VisitTypeInline(*base_.type(), this));
return out_;
}
template <typename Iterator>
Result<std::shared_ptr<StructArray>> Diff(Iterator base_begin, Iterator base_end,
Iterator target_begin, Iterator target_end) {
QuadraticSpaceMyersDiff<Iterator> impl(base_begin, base_end, target_begin,
target_end);
while (!impl.Done()) {
impl.Next();
}
return impl.GetEdits(pool_);
}
const Array& base_;
const Array& target_;
MemoryPool* pool_;
std::shared_ptr<StructArray> out_;
};
Result<std::shared_ptr<StructArray>> Diff(const Array& base, const Array& target,
MemoryPool* pool) {
if (!base.type()->Equals(target.type())) {
return Status::TypeError("only taking the diff of like-typed arrays is supported.");
}
return DiffImpl{base, target, pool, nullptr}.Diff();
}
using Formatter = std::function<void(const Array&, int64_t index, std::ostream*)>;
static Result<Formatter> MakeFormatter(const DataType& type);
class MakeFormatterImpl {
public:
Result<Formatter> Make(const DataType& type) && {
RETURN_NOT_OK(VisitTypeInline(type, this));
return std::move(impl_);
}
private:
template <typename VISITOR>
friend Status VisitTypeInline(const DataType&, VISITOR*);
// factory implementation
Status Visit(const BooleanType&) {
impl_ = [](const Array& array, int64_t index, std::ostream* os) {
*os << (checked_cast<const BooleanArray&>(array).Value(index) ? "true" : "false");
};
return Status::OK();
}
// format Numerics with std::ostream defaults
template <typename T>
enable_if_number<T, Status> Visit(const T&) {
impl_ = [](const Array& array, int64_t index, std::ostream* os) {
const auto& numeric = checked_cast<const NumericArray<T>&>(array);
if (sizeof(decltype(numeric.Value(index))) == sizeof(char)) {
// override std::ostream defaults for /(u|)int8_t/ since they are
// formatted as potentially unprintable/tty borking characters
*os << static_cast<int16_t>(numeric.Value(index));
} else {
*os << numeric.Value(index);
}
};
return Status::OK();
}
template <typename T>
enable_if_date<T, Status> Visit(const T&) {
using unit = typename std::conditional<std::is_same<T, Date32Type>::value,
arrow_vendored::date::days,
std::chrono::milliseconds>::type;
static arrow_vendored::date::sys_days epoch{arrow_vendored::date::jan / 1 / 1970};
impl_ = [](const Array& array, int64_t index, std::ostream* os) {
unit value(checked_cast<const NumericArray<T>&>(array).Value(index));
*os << arrow_vendored::date::format("%F", value + epoch);
};
return Status::OK();
}
template <typename T>
enable_if_time<T, Status> Visit(const T&) {
impl_ = MakeTimeFormatter<T, false>("%T");
return Status::OK();
}
Status Visit(const TimestampType&) {
impl_ = MakeTimeFormatter<TimestampType, true>("%F %T");
return Status::OK();
}
Status Visit(const DayTimeIntervalType&) {
impl_ = [](const Array& array, int64_t index, std::ostream* os) {
auto day_millis = checked_cast<const DayTimeIntervalArray&>(array).Value(index);
*os << day_millis.days << "d" << day_millis.milliseconds << "ms";
};
return Status::OK();
}
// format Binary, LargeBinary and FixedSizeBinary in hexadecimal
template <typename T>
enable_if_binary_like<T, Status> Visit(const T&) {
using ArrayType = typename TypeTraits<T>::ArrayType;
impl_ = [](const Array& array, int64_t index, std::ostream* os) {
*os << HexEncode(checked_cast<const ArrayType&>(array).GetView(index));
};
return Status::OK();
}
// format Strings with \"\n\r\t\\ escaped
template <typename T>
enable_if_string_like<T, Status> Visit(const T&) {
using ArrayType = typename TypeTraits<T>::ArrayType;
impl_ = [](const Array& array, int64_t index, std::ostream* os) {
*os << "\"" << Escape(checked_cast<const ArrayType&>(array).GetView(index)) << "\"";
};
return Status::OK();
}
// format Decimals with Decimal128Array::FormatValue
Status Visit(const Decimal128Type&) {
impl_ = [](const Array& array, int64_t index, std::ostream* os) {
*os << checked_cast<const Decimal128Array&>(array).FormatValue(index);
};
return Status::OK();
}
template <typename T>
enable_if_list_like<T, Status> Visit(const T& t) {
struct ListImpl {
explicit ListImpl(Formatter f) : values_formatter_(std::move(f)) {}
void operator()(const Array& array, int64_t index, std::ostream* os) {
const auto& list_array =
checked_cast<const typename TypeTraits<T>::ArrayType&>(array);
*os << "[";
for (int32_t i = 0; i < list_array.value_length(index); ++i) {
if (i != 0) {
*os << ", ";
}
values_formatter_(*list_array.values(), i + list_array.value_offset(index), os);
}
*os << "]";
}
Formatter values_formatter_;
};
ARROW_ASSIGN_OR_RAISE(auto values_formatter, MakeFormatter(*t.value_type()));
impl_ = ListImpl(std::move(values_formatter));
return Status::OK();
}
// TODO(bkietz) format maps better
Status Visit(const StructType& t) {
struct StructImpl {
explicit StructImpl(std::vector<Formatter> f) : field_formatters_(std::move(f)) {}
void operator()(const Array& array, int64_t index, std::ostream* os) {
const auto& struct_array = checked_cast<const StructArray&>(array);
*os << "{";
for (int i = 0, printed = 0; i < struct_array.num_fields(); ++i) {
if (printed != 0) {
*os << ", ";
}
if (struct_array.field(i)->IsNull(index)) {
continue;
}
++printed;
*os << struct_array.struct_type()->child(i)->name() << ": ";
field_formatters_[i](*struct_array.field(i), index, os);
}
*os << "}";
}
std::vector<Formatter> field_formatters_;
};
std::vector<Formatter> field_formatters(t.num_children());
for (int i = 0; i < t.num_children(); ++i) {
ARROW_ASSIGN_OR_RAISE(field_formatters[i], MakeFormatter(*t.child(i)->type()));
}
impl_ = StructImpl(std::move(field_formatters));
return Status::OK();
}
Status Visit(const UnionType& t) {
struct UnionImpl {
explicit UnionImpl(std::vector<Formatter> f) : field_formatters_(std::move(f)) {}
void DoFormat(const UnionArray& array, int64_t index, int64_t child_index,
std::ostream* os) {
auto type_code = array.raw_type_codes()[index];
const auto& child = *array.child(array.child_id(index));
*os << "{" << static_cast<int16_t>(type_code) << ": ";
if (child.IsNull(child_index)) {
*os << "null";
} else {
field_formatters_[type_code](child, child_index, os);
}
*os << "}";
}
std::vector<Formatter> field_formatters_;
};
struct SparseImpl : UnionImpl {
using UnionImpl::UnionImpl;
void operator()(const Array& array, int64_t index, std::ostream* os) {
const auto& union_array = checked_cast<const UnionArray&>(array);
DoFormat(union_array, index, index, os);
}
};
struct DenseImpl : UnionImpl {
using UnionImpl::UnionImpl;
void operator()(const Array& array, int64_t index, std::ostream* os) {
const auto& union_array = checked_cast<const UnionArray&>(array);
DoFormat(union_array, index, union_array.raw_value_offsets()[index], os);
}
};
std::vector<Formatter> field_formatters(t.max_type_code() + 1);
for (int i = 0; i < t.num_children(); ++i) {
auto type_id = t.type_codes()[i];
ARROW_ASSIGN_OR_RAISE(field_formatters[type_id],
MakeFormatter(*t.child(i)->type()));
}
if (t.mode() == UnionMode::SPARSE) {
impl_ = SparseImpl(std::move(field_formatters));
} else {
impl_ = DenseImpl(std::move(field_formatters));
}
return Status::OK();
}
Status Visit(const NullType& t) {
return Status::NotImplemented("formatting diffs between arrays of type ", t);
}
Status Visit(const DictionaryType& t) {
return Status::NotImplemented("formatting diffs between arrays of type ", t);
}
Status Visit(const ExtensionType& t) {
return Status::NotImplemented("formatting diffs between arrays of type ", t);
}
Status Visit(const DurationType& t) {
return Status::NotImplemented("formatting diffs between arrays of type ", t);
}
Status Visit(const MonthIntervalType& t) {
return Status::NotImplemented("formatting diffs between arrays of type ", t);
}
template <typename T, bool AddEpoch>
Formatter MakeTimeFormatter(const std::string& fmt_str) {
return [fmt_str](const Array& array, int64_t index, std::ostream* os) {
auto fmt = fmt_str.c_str();
auto unit = checked_cast<const T&>(*array.type()).unit();
auto value = checked_cast<const NumericArray<T>&>(array).Value(index);
using arrow_vendored::date::format;
using std::chrono::nanoseconds;
using std::chrono::microseconds;
using std::chrono::milliseconds;
using std::chrono::seconds;
if (AddEpoch) {
static arrow_vendored::date::sys_days epoch{arrow_vendored::date::jan / 1 / 1970};
switch (unit) {
case TimeUnit::NANO:
*os << format(fmt, static_cast<nanoseconds>(value) + epoch);
break;
case TimeUnit::MICRO:
*os << format(fmt, static_cast<microseconds>(value) + epoch);
break;
case TimeUnit::MILLI:
*os << format(fmt, static_cast<milliseconds>(value) + epoch);
break;
case TimeUnit::SECOND:
*os << format(fmt, static_cast<seconds>(value) + epoch);
break;
}
return;
}
switch (unit) {
case TimeUnit::NANO:
*os << format(fmt, static_cast<nanoseconds>(value));
break;
case TimeUnit::MICRO:
*os << format(fmt, static_cast<microseconds>(value));
break;
case TimeUnit::MILLI:
*os << format(fmt, static_cast<milliseconds>(value));
break;
case TimeUnit::SECOND:
*os << format(fmt, static_cast<seconds>(value));
break;
}
};
}
Formatter impl_;
};
static Result<Formatter> MakeFormatter(const DataType& type) {
return MakeFormatterImpl{}.Make(type);
}
Status VisitEditScript(
const Array& edits,
const std::function<Status(int64_t delete_begin, int64_t delete_end,
int64_t insert_begin, int64_t insert_end)>& visitor) {
static const auto edits_type =
struct_({field("insert", boolean()), field("run_length", int64())});
DCHECK(edits.type()->Equals(*edits_type));
DCHECK_GE(edits.length(), 1);
auto insert = checked_pointer_cast<BooleanArray>(
checked_cast<const StructArray&>(edits).field(0));
auto run_lengths =
checked_pointer_cast<Int64Array>(checked_cast<const StructArray&>(edits).field(1));
DCHECK(!insert->Value(0));
auto length = run_lengths->Value(0);
int64_t base_begin, base_end, target_begin, target_end;
base_begin = base_end = target_begin = target_end = length;
for (int64_t i = 1; i < edits.length(); ++i) {
if (insert->Value(i)) {
++target_end;
} else {
++base_end;
}
length = run_lengths->Value(i);
if (length != 0) {
RETURN_NOT_OK(visitor(base_begin, base_end, target_begin, target_end));
base_begin = base_end = base_end + length;
target_begin = target_end = target_end + length;
}
}
if (length == 0) {
return visitor(base_begin, base_end, target_begin, target_end);
}
return Status::OK();
}
class UnifiedDiffFormatter {
public:
UnifiedDiffFormatter(std::ostream* os, Formatter formatter)
: os_(os), formatter_(std::move(formatter)) {}
Status operator()(int64_t delete_begin, int64_t delete_end, int64_t insert_begin,
int64_t insert_end) {
*os_ << "@@ -" << delete_begin << ", +" << insert_begin << " @@" << std::endl;
for (int64_t i = delete_begin; i < delete_end; ++i) {
*os_ << "-";
if (base_->IsValid(i)) {
formatter_(*base_, i, &*os_);
} else {
*os_ << "null";
}
*os_ << std::endl;
}
for (int64_t i = insert_begin; i < insert_end; ++i) {
*os_ << "+";
if (target_->IsValid(i)) {
formatter_(*target_, i, &*os_);
} else {
*os_ << "null";
}
*os_ << std::endl;
}
return Status::OK();
}
Status operator()(const Array& edits, const Array& base, const Array& target) {
if (edits.length() == 1) {
return Status::OK();
}
base_ = &base;
target_ = ⌖
*os_ << std::endl;
return VisitEditScript(edits, *this);
}
private:
std::ostream* os_ = nullptr;
const Array* base_ = nullptr;
const Array* target_ = nullptr;
Formatter formatter_;
};
Result<std::function<Status(const Array& edits, const Array& base, const Array& target)>>
MakeUnifiedDiffFormatter(const DataType& type, std::ostream* os) {
ARROW_ASSIGN_OR_RAISE(auto formatter, MakeFormatter(type));
return UnifiedDiffFormatter(os, std::move(formatter));
}
} // namespace arrow
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