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AK: Add a BinarySearch template implementation
binary_search takes a haystack, a size, a needle and a compare function. The compare function should return negative if a < b, positive if a > b and 0 if a == b. The "sane default" compare function is integral_compare which implements this with subtraction a - b. binary_search returns a pointer to a matching element, NOT necessarily the FIRST matching element. It returns a nullptr if the element was not found. This patch includes tests for binary_search.
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82
AK/Tests/TestBinarySearch.cpp
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82
AK/Tests/TestBinarySearch.cpp
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#include <AK/TestSuite.h>
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#include <AK/BinarySearch.h>
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TEST_CASE(vector_ints)
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{
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Vector<int> ints;
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ints.append(1);
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ints.append(2);
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ints.append(3);
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auto test1 = *binary_search(ints.data(), ints.size(), 1, AK::integral_compare<int>);
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auto test2 = *binary_search(ints.data(), ints.size(), 2, AK::integral_compare<int>);
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auto test3 = *binary_search(ints.data(), ints.size(), 3, AK::integral_compare<int>);
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EXPECT_EQ(test1, 1);
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EXPECT_EQ(test2, 2);
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EXPECT_EQ(test3, 3);
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}
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TEST_CASE(array_doubles)
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{
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double doubles[] = { 1.1, 9.9, 33.33 };
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auto test1 = *binary_search(doubles, 3, 1.1, AK::integral_compare<double>);
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auto test2 = *binary_search(doubles, 3, 9.9, AK::integral_compare<double>);
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auto test3 = *binary_search(doubles, 3, 33.33, AK::integral_compare<double>);
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EXPECT_EQ(test1, 1.1);
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EXPECT_EQ(test2, 9.9);
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EXPECT_EQ(test3, 33.33);
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}
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TEST_CASE(vector_strings)
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{
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Vector<String> strings;
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strings.append("bat");
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strings.append("cat");
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strings.append("dog");
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auto string_compare = [](const String& a, const String& b) -> int {
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return strcmp(a.characters(), b.characters());
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};
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auto test1 = *binary_search(strings.data(), strings.size(), String("bat"), string_compare);
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auto test2 = *binary_search(strings.data(), strings.size(), String("cat"), string_compare);
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auto test3 = *binary_search(strings.data(), strings.size(), String("dog"), string_compare);
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EXPECT_EQ(test1, String("bat"));
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EXPECT_EQ(test2, String("cat"));
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EXPECT_EQ(test3, String("dog"));
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}
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TEST_CASE(single_element)
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{
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Vector<int> ints;
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ints.append(1);
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auto test1 = *binary_search(ints.data(), ints.size(), 1, AK::integral_compare<int>);
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EXPECT_EQ(test1, 1);
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}
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TEST_CASE(not_found)
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{
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Vector<int> ints;
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ints.append(1);
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ints.append(2);
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ints.append(3);
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auto test1 = binary_search(ints.data(), ints.size(), -1, AK::integral_compare<int>);
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auto test2 = binary_search(ints.data(), ints.size(), 0, AK::integral_compare<int>);
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auto test3 = binary_search(ints.data(), ints.size(), 4, AK::integral_compare<int>);
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EXPECT_EQ(test1, nullptr);
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EXPECT_EQ(test2, nullptr);
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EXPECT_EQ(test3, nullptr);
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}
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TEST_CASE(no_elements)
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{
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Vector<int> ints;
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auto test1 = binary_search(ints.data(), ints.size(), 1, AK::integral_compare<int>);
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EXPECT_EQ(test1, nullptr);
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}
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TEST_MAIN(BinarySearch)
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