subhasis256 / pythonicpp

A library for adding python-like syntactic sugar to C++11

pythonic++

pythonic++: A library for adding python-like syntactic sugar to C++11.

This header file tries to create some simple utility functions that are inspired by Python inbuilt functions such as len, min, etc. A brief summary of all the functionality in the package is below

The base iterable<T,R> type is at the core of the provided functionality. This class is the base of a generic iterable that supports forward iteration only, and exopses an iterator that is either of ITERATOR_END type, or ITERATOR_NORMAL type. Note that we treat any two END iterators as equal, while any other pair of iterators as non-equal. This is because in a generic iterable there is no way to ensure that two iterators are pointing to the exact same iteration point. Thus, the only type of iteration supported by any iterable is of the type

for(auto it = itr.begin(); it != itr.end(); ++it) {...}

OR

for(auto v : itr) {...}

Any iterable supports the following methods:

• filter(Function f): returns another iterable that only contains elements x for which f(x) == true.
• transform(Function f): returns another iterable with the values f(x) for each x in the iterable.
• enumerate(): returns another iterable that contains a pair<size_t, T>(i,x) where i is the iteration index for each x.
• max(): returns the maximum value x seen in this iterable.
• max(Function f): returns the value x such that f(x) is maximum.
• min(): returns the minimum value x seen in this iterable.
• min(Function f): returns the value x such that f(x) is minimum.
• len(): returns the length of this iterable.
• foreach(Function f): returns the original iterable while performing the computation f(x) for each x. Note that this does not a changed iterable. For changing, see the function transform.
• to_vector(): returns a vector<T> that contains each value from this iterable in sequence.
• (Pushable): casts the iterable to the type Pushable that supports a push_back operation.

For STL containers that are not derived from the iterable class but support iteration by begin(), end(), and ++, the library defines convenience functions similar to the above. Specifically each iterable::member_function(...) has a counterpart member_function(v, ...) which can operate on any such STL container. Two more functions are defined on STL containers:

• foreach(V &v, Function fun, IterFunction ifun): This is equivalent to for(auto it = v.begin(); it != v.end(); it = iterfun(it)) { fun(*it); }
• foreach(V &v, Function fun, V::iterator beginit, V::iterator endit, IterFunction ifun): This is equivalent to for(auto it = beginit; it != endit; it = iterfun(it)) { fun(*it); }

Also, there is a function range() which iterates over all integers in a given range. The variations are:

• range(N): iterates through 0, 1, ..., N-1
• range(M,N): iterates through M, M+1, ..., N-1
• range(M,N,step): iterates through M, M+step, M+2*step, ..., N-1

Some simple examples that illustrate the functionality of the library is in the tests/test.cpp file.