boolinq 3.0
Super tiny C++11 single-file header-only LINQ template library
Just imagine .NET Framework LINQ support for STL/Qt collections :)
Get source code here: boolinq.h
Wanna demo?
Example with integers
int src[] = {1,2,3,4,5,6,7,8};
auto dst = from(src).where( [](int a) { return a % 2 == 1; }) // 1,3,5,7
.select([](int a) { return a * 2; }) // 2,6,10,14
.where( [](int a) { return a > 2 && a < 12; }) // 6,10
.toStdVector();
// dst type: std::vector<int>
// dst items: 6,10Example with structs
struct Man {
std::string name;
int age;
};
Man src[] = {
{"Kevin",14},
{"Anton",18},
{"Agata",17},
{"Terra",20},
{"Layer",15},
};
auto dst = from(src).where( [](const Man & man) { return man.age < 18; })
.orderBy([](const Man & man) { return man.age; })
.select( [](const Man & man) { return man.name; })
.toStdVector();
// dst type: std::vector<std::string>
// dst items: "Kevin", "Layer", "Agata"Interesting example
struct Message {
std::string PhoneA;
std::string PhoneB;
std::string Text;
};
Message messages[] = {
{"Anton","Troll","Hello, friend!"},
{"Denis","Wride","OLOLO"},
{"Anton","Papay","WTF?"},
{"Denis","Maloy","How r u?"},
{"Denis","Wride","Param-pareram!"},
};
int DenisUniqueContactCount =
from(messages).where( [](const Message & msg) { return msg.PhoneA == "Denis"; })
.distinct([](const Message & msg) { return msg.PhoneB; })
.count();
// DenisUniqueContactCount == 2 Test in C++14 using auto
The following test requires C++14 GroupByTestComplex.cpp It uses auto in order to avoid a very long lambda argument type. The return type of a function or lambda expression can be deduced by its operand since C++14. The CMake file is changed so that this test runs with C++14.
TEST(GroupBy, CountTaxes)
{
struct Tax {
std::string name;
int amount_1;
int amount_2;
bool operator ==(const Tax & tax) const {
return name == tax.name
&& amount_1 == tax.amount_1
&& amount_2 == tax.amount_2;
}
};
std::vector<Tax> taxes = {
{"tax 1", 1, 1},
{"tax 2", 1, 1},
{"tax 1", 2, 2},
{"tax 3", 3, 3},
{"tax 1", 4, 4},
};
Tax ans[] = {
{"tax 1", 7, 7},
{"tax 2", 1, 1},
{"tax 3", 3, 3},
};
auto dst = from(taxes)
.groupBy([](const Tax & a){return a.name;})
.select([](const auto & pair){ // use of auto here needs c++14
return Tax {
pair.first,
pair.second.sum([](const Tax & a){return a.amount_1;}),
pair.second.sum([](const Tax & a){return a.amount_2;})
};
});
CheckRangeEqArray(dst, ans);
}Containers supported?
- C++: Native arrays, pairs of pointers
- STL: list, stack, queue, vector, deque, set, map, any compatible ....
- Qt: QList, QVector, QSet, QMap.
Operators supported?
Filters and reorders:
where(predicate),where_i(predicate)take(count),takeWhile(predicate),takeWhile_i(predicate)skip(count),skipWhile(predicate),skipWhile_i(predicate)orderBy(),orderBy(transform)distinct(),distinct(transform)append(items),prepend(items)concat(linq)reverse()cast<T>()
Transformers:
select(transform),select_i(transform)groupBy(transform)selectMany(transfom)
Aggregators:
all(),all(predicate)any(),any(lambda)sum(),sum<T>(),sum(lambda)avg(),avg<T>(),avg(lambda)min(),min(lambda)max(),max(lambda)count(),count(value),count(predicate)contains(value)elementAt(index)first(),first(filter),firstOrDefault(),firstOrDefault(filter)last(),last(filter),lastOrDefault(),lastOrDefault(filter)toStdSet(),toStdList(),toStdDeque(),toStdVector()
Bits and Bytes:
bytes<T>(ByteDirection?)unbytes<T>(ByteDirection?)bits(BitsDirection?, BytesDirection?)unbits<T = unsigned char>(BitsDirection?, BytesDirection?)
Coming soon:
- gz()
- ungz()
- leftJoin
- rightJoin
- crossJoin
- fullJoin