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AK: Make binary_search signature more generic.

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asynts 2020-12-29 16:13:16 +01:00 committed by Andreas Kling
parent 35c4338625
commit 50d24e4f98
Notes: sideshowbarker 2024-07-19 00:25:09 +09:00 
Author: https://github.com/asynts
Commit: https://github.com/SerenityOS/serenity/commit/50d24e4f98b
Pull-request: https://github.com/SerenityOS/serenity/pull/4633
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/alimpfard
6 changed files with 63 additions and 53 deletions
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18
AK/BinarySearch.h
View file

@ -32,14 +32,16 @@
namespace AK {
template<typename T>
constexpr int integral_compare(const typename RemoveConst<T>::Type& a, const typename RemoveConst<T>::Type& b)
{
return a - b;
}
struct IntegralComparator {
constexpr auto operator()(auto& lhs, auto& rhs) { return lhs - rhs; }
};
template<typename T, typename Compare>
constexpr T* binary_search(Span<T> haystack, const typename RemoveConst<T>::Type& needle, Compare compare = integral_compare, size_t* nearby_index = nullptr)
template<typename Container, typename Needle, typename Comparator = IntegralComparator>
constexpr auto binary_search(
Container&& haystack,
Needle&& needle,
size_t* nearby_index = nullptr,
Comparator comparator = Comparator {}) -> decltype(&haystack[0])
{
if (haystack.size() == 0) {
if (nearby_index)
@ -51,7 +53,7 @@ constexpr T* binary_search(Span<T> haystack, const typename RemoveConst<T>::Type
size_t high = haystack.size() - 1;
while (low <= high) {
size_t middle = low + ((high - low) / 2);
int comparison = compare(needle, haystack[middle]);
auto comparison = comparator(needle, haystack[middle]);
if (comparison < 0)
if (middle != 0)
high = middle - 1;

56
AK/Tests/TestBinarySearch.cpp
View file

@ -38,24 +38,32 @@ TEST_CASE(vector_ints)
ints.append(2);
ints.append(3);
auto test1 = *binary_search(ints.span(), 1, AK::integral_compare<int>);
auto test2 = *binary_search(ints.span(), 2, AK::integral_compare<int>);
auto test3 = *binary_search(ints.span(), 3, AK::integral_compare<int>);
auto test1 = *binary_search(ints, 1);
auto test2 = *binary_search(ints, 2);
auto test3 = *binary_search(ints, 3);
EXPECT_EQ(test1, 1);
EXPECT_EQ(test2, 2);
EXPECT_EQ(test3, 3);
}
TEST_CASE(span_rvalue_reference)
{
Array<long, 3> array { 1, 2, 3 };
size_t nearby_index = 0;
auto* pointer = binary_search(array.span(), 2, &nearby_index);
EXPECT_EQ(nearby_index, 1u);
EXPECT_EQ(pointer, &array[1]);
}
TEST_CASE(array_doubles)
{
double doubles[] = { 1.1, 9.9, 33.33 };
Array<double, 3> array { 1.1, 9.9, 33.33 };
auto test1 = *binary_search(Span<double> { doubles, 3 }, 1.1, AK::integral_compare<double>);
auto test2 = *binary_search(Span<double> { doubles, 3 }, 9.9, AK::integral_compare<double>);
auto test3 = *binary_search(Span<double> { doubles, 3 }, 33.33, AK::integral_compare<double>);
EXPECT_EQ(test1, 1.1);
EXPECT_EQ(test2, 9.9);
EXPECT_EQ(test3, 33.33);
EXPECT_EQ(binary_search(array, 1.1), &array[0]);
EXPECT_EQ(binary_search(array, 33.33), &array[2]);
EXPECT_EQ(binary_search(array, 9.9), &array[1]);
}
TEST_CASE(vector_strings)
@ -68,9 +76,9 @@ TEST_CASE(vector_strings)
auto string_compare = [](const String& a, const String& b) -> int {
return strcmp(a.characters(), b.characters());
};
auto test1 = *binary_search(strings.span(), String("bat"), string_compare);
auto test2 = *binary_search(strings.span(), String("cat"), string_compare);
auto test3 = *binary_search(strings.span(), String("dog"), string_compare);
auto test1 = *binary_search(strings, String("bat"), nullptr, string_compare);
auto test2 = *binary_search(strings, String("cat"), nullptr, string_compare);
auto test3 = *binary_search(strings, String("dog"), nullptr, string_compare);
EXPECT_EQ(test1, String("bat"));
EXPECT_EQ(test2, String("cat"));
EXPECT_EQ(test3, String("dog"));
@ -81,7 +89,7 @@ TEST_CASE(single_element)
Vector<int> ints;
ints.append(1);
auto test1 = *binary_search(ints.span(), 1, AK::integral_compare<int>);
auto test1 = *binary_search(ints, 1);
EXPECT_EQ(test1, 1);
}
@ -92,9 +100,9 @@ TEST_CASE(not_found)
ints.append(2);
ints.append(3);
auto test1 = binary_search(ints.span(), -1, AK::integral_compare<int>);
auto test2 = binary_search(ints.span(), 0, AK::integral_compare<int>);
auto test3 = binary_search(ints.span(), 4, AK::integral_compare<int>);
auto test1 = binary_search(ints, -1);
auto test2 = binary_search(ints, 0);
auto test3 = binary_search(ints, 4);
EXPECT_EQ(test1, nullptr);
EXPECT_EQ(test2, nullptr);
EXPECT_EQ(test3, nullptr);
@ -104,7 +112,7 @@ TEST_CASE(no_elements)
{
Vector<int> ints;
auto test1 = binary_search(ints.span(), 1, AK::integral_compare<int>);
auto test1 = binary_search(ints, 1);
EXPECT_EQ(test1, nullptr);
}
@ -112,15 +120,9 @@ TEST_CASE(constexpr_array_search)
{
constexpr Array<int, 3> array = { 1, 17, 42 };
constexpr auto test1 = *binary_search(array.span(), 1, AK::integral_compare<int>);
constexpr auto test2 = *binary_search(array.span(), 17, AK::integral_compare<int>);
constexpr auto test3 = *binary_search(array.span(), 42, AK::integral_compare<int>);
constexpr auto test4 = binary_search(array.span(), 99, AK::integral_compare<int>);
static_assert(test1 == 1, "Binary search should find value at compile-time.");
static_assert(test2 == 17, "Binary search should find value at compile-time.");
static_assert(test3 == 42, "Binary search should find value at compile-time.");
static_assert(test4 == nullptr, "Binary search should return nullptr for missing value at compile-time.");
static_assert(binary_search(array, 42) == &array[2]);
static_assert(binary_search(array, 17) == &array[1]);
static_assert(binary_search(array, 3) == nullptr);
}
TEST_MAIN(BinarySearch)

8
Kernel/VM/RangeAllocator.cpp
View file

@ -181,10 +181,10 @@ void RangeAllocator::deallocate(Range range)
size_t nearby_index = 0;
auto* existing_range = binary_search(
m_available_ranges.span(), range, [](auto& a, auto& b) {
return a.base().get() - b.end().get();
},
&nearby_index);
m_available_ranges.span(),
range,
&nearby_index,
[](auto& a, auto& b) { return a.base().get() - b.end().get(); });
size_t inserted_index = 0;
if (existing_range) {

2
Libraries/LibCompress/Deflate.cpp
View file

@ -112,7 +112,7 @@ u32 CanonicalCode::read_symbol(InputBitStream& stream) const
// FIXME: This seems really inefficient, this could be an index into an array instead.
size_t index;
if (AK::binary_search(m_symbol_codes.span(), code_bits, AK::integral_compare<u32>, &index))
if (AK::binary_search(m_symbol_codes.span(), code_bits, &index))
return m_symbol_values[index];
}
}

8
Libraries/LibLine/XtermSuggestionDisplay.cpp
View file

@ -187,12 +187,14 @@ size_t XtermSuggestionDisplay::fit_to_page_boundary(size_t selection_index)
size_t index = 0;
auto* match = binary_search(
m_pages.span(), { selection_index, selection_index }, [](auto& a, auto& b) -> int {
m_pages.span(),
PageRange { selection_index, selection_index },
&index,
[](auto& a, auto& b) -> int {
if (a.start >= b.start && a.start < b.end)
return 0;
return a.start - b.start;
},
&index);
});
if (!match)
return m_pages.size() - 1;

24
Shell/Shell.cpp
View file

@ -543,9 +543,11 @@ bool Shell::is_runnable(const StringView& name)
if (access(name.to_string().characters(), X_OK) == 0)
return true;
return !!binary_search(cached_path.span(), name.to_string(), [](const String& name, const String& program) -> int {
return strcmp(name.characters(), program.characters());
});
return binary_search(
cached_path.span(),
name.to_string(),
nullptr,
[](auto& name, auto& program) { return strcmp(name.characters(), program.characters()); });
}
int Shell::run_command(const StringView& cmd)
@ -1154,10 +1156,10 @@ void Shell::add_entry_to_cache(const String& entry)
{
size_t index = 0;
auto match = binary_search(
cached_path.span(), entry, [](const String& name, const String& program) -> int {
return strcmp(name.characters(), program.characters());
},
&index);
cached_path.span(),
entry,
&index,
[](auto& name, auto& program) { return strcmp(name.characters(), program.characters()); });
if (match)
return;
@ -1263,9 +1265,11 @@ Vector<Line::CompletionSuggestion> Shell::complete_path(const String& base, cons
Vector<Line::CompletionSuggestion> Shell::complete_program_name(const String& name, size_t offset)
{
auto match = binary_search(cached_path.span(), name, [](const String& name, const String& program) -> int {
return strncmp(name.characters(), program.characters(), name.length());
});
auto match = binary_search(
cached_path.span(),
name,
nullptr,
[](auto& name, auto& program) { return strncmp(name.characters(), program.characters(), name.length()); });
if (!match)
return complete_path("", name, offset);