C++ 拡張機能の作成

git clone https://github.com/villagesql/vsql-extension-template my-extension
cd my-extension

mkdir build && cd build
cmake .. -DVillageSQL_BUILD_DIR=/path/to/villagesql/build
make

#include <villagesql/vsql.h>

using namespace vsql;

void my_reverse_impl(StringArg input, StringResult out) {
    if (input.is_null()) {
        out.set_null();
        return;
    }

    auto sv = input.value();   // std::string_view
    auto buf = out.buffer();   // Span<char>

    if (sv.size() > buf.size()) {
        out.error("my_reverse: input exceeds buffer size");
        return;
    }

    for (size_t i = 0; i < sv.size(); i++) {
        buf.data()[i] = sv[sv.size() - 1 - i];
    }
    out.set_length(sv.size());
}

VEF_GENERATE_ENTRY_POINTS(
    make_extension()
        .func(make_func<&my_reverse_impl>("my_reverse")
            .returns(STRING)
            .param(STRING)
            .build())
)

void count_vowels_impl(StringArg input, IntResult out) {
    if (input.is_null()) { out.set_null(); return; }

    long long count = 0;
    for (char c : input.value()) {
        char lower = std::tolower(c);
        if (lower == 'a' || lower == 'e' || lower == 'i' ||
            lower == 'o' || lower == 'u') {
            count++;
        }
    }
    out.set(count);
}

.func(make_func<&my_reverse_impl>("my_reverse")
    .returns(STRING)
    .param(STRING)
    .deterministic()
    .build())

make
make install

INSTALL EXTENSION my_extension;

SELECT * FROM INFORMATION_SCHEMA.EXTENSIONS WHERE EXTENSION_NAME = 'my_extension';

SELECT my_reverse('Hello, World!');
-- → !dlroW ,olleH

-- mysql-test/t/basic.test
INSTALL EXTENSION my_extension;
SELECT my_reverse('abc');
SELECT my_reverse('');
SELECT my_reverse(NULL);
UNINSTALL EXTENSION my_extension;

cd /path/to/villagesql/build/mysql-test
perl mysql-test-run.pl --suite=/path/to/my-extension/mysql-test --record
perl mysql-test-run.pl --suite=/path/to/my-extension/mysql-test