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Stream

# Stream

Printing a Vec2d for debugging, or building up a Text piece by piece as game logic runs, shouldn't require manual conversions every time.

Overview

RE:MAKE 2D extends the standard C++ streams so its own types behave naturally with them. This lives in the header "remake2d/stream.hpp", covering two cases: printing/parsing base types through std::ostream/std::istream, and building up a Text through chained <<. DataFile also gets dedicated <</>> overloads for any type implementing ISavable.

Printing base types

Vec2d, Fact2d, Dim2d, Color and Area all behave like native types in front of std::cout:

std::ostream& operator<<(std::ostream&, const Vec2d&)  noexcept;
std::ostream& operator<<(std::ostream&, const Fact2d&) noexcept;
std::ostream& operator<<(std::ostream&, const Dim2d&)  noexcept;
std::ostream& operator<<(std::ostream&, const Color&)  noexcept;
std::ostream& operator<<(std::ostream&, const Area&)   noexcept;

rmk::Vec2d pos = {100, 200};
std::cout << pos << "\n"; // [ x : 100  |  y : 200 ]

The reverse works too, reading a comma-separated line from a std::istream:

std::istream& operator>>(std::istream&, Vec2d&);
std::istream& operator>>(std::istream&, Fact2d&);
std::istream& operator>>(std::istream&, Dim2d&);
std::istream& operator>>(std::istream&, Color&);
std::istream& operator>>(std::istream&, Area&);

std::istringstream iss("100,200");
rmk::Vec2d pos;
iss >> pos; // { 100, 200 }

Building up Text

Rather than calling write/append repeatedly, a Text can be built by simply chaining <<, just like std::cout:

Text& operator<<(Text&, Text&)            noexcept;
Text& operator<<(Text&, std::string_view) noexcept;
Text& operator<<(Text&, fmt)              noexcept;
  • The Text overload appends the other Text's content.
  • The std::string_view overload appends the given string.
  • The fmt overload appends a formatting token: fmt::nl for a newline, fmt::tab for spacing, fmt::endl to mark the next append as a
  • replacement rather than a continuation, fmt::flush to clear the text.
rmk::Text label("arial", {100, 100});

label << "Score : " << fmt::nl << "0";

Since any type satisfying IsBasicType already knows how to print itself to an ostream, it can also be streamed directly into a Text without manual conversion:

template<IsBasicType T> Text& operator<<(Text&, const T&) noexcept;

rmk::Vec2d pos = {50, 50};
label << "Position : " << pos; // uses operator<<(ostream&, Vec2d&) internally

The other way around, operator>> replaces a Text's entire content with a line read from a stream:

std::istream& operator>>(std::istream&, Text&) noexcept;

std::istringstream iss("Hello world");
iss >> label;

Saving and loading with DataFile

The same idea applies to saving: any type implementing ISavable can be saved or reloaded with <</>>, as a shorthand for save/load:

template<IsSavable T> DataFile& operator<<(DataFile&, const T&);
template<IsSavable T> DataFile& operator>>(DataFile&, T&);

rmk::DataFile file("save1");

file << player; // equivalent to file.save
file >> player; // equivalent to file.load

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