I/O

in
out

The I/O operators: << and >> work generically on all Fusion sequences. The global operator<< has been overloaded for generic output streams such that _sequence_s are output by recursively calling operator<< for each element. Analogously, the global operator>> has been overloaded to extract _sequence_s from generic input streams by recursively calling operator>> for each element.

The default delimiter between the elements is space, and the Sequence is enclosed in parenthesis. For Example:

vector<float, int, std::string> a(1.0f, 2, std::string("Howdy folks!");
cout << a;

outputs the vector as: (1.0 2 Howdy folks!)

The library defines three manipulators for changing the default behavior:

Manipulators

tuple_open(arg): Defines the character that is output before the first element.
tuple_close(arg): Defines the character that is output after the last element.
tuple_delimiter(arg): Defines the delimiter character between elements.

The argument to tuple_open, tuple_close and tuple_delimiter may be a char, wchar_t, a C-string, or a wide C-string.

Example:

std::cout << tuple_open('[') << tuple_close(']') << tuple_delimiter(", ") << a;

outputs the same vector, a as: [1.0, 2, Howdy folks!]

The same manipulators work with operator>> and istream as well. Suppose the std::cin stream contains the following data:

(1 2 3) [4:5]

The code:

vector<int, int, int> i;
vector<int, int> j;

std::cin >> i;
std::cin >> set_open('[') >> set_close(']') >> set_delimiter(':');
std::cin >> j;

reads the data into the _vector_s i and j.

Note that extracting _sequence_s with std::string or C-style string elements does not generally work, since the streamed Sequence representation may not be unambiguously parseable.

Header

#include <boost/fusion/sequence/io.hpp>