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+.. _string-formatting-api:
+
+*************
+API Reference
+*************
+
+The {fmt} library API consists of the following parts:
+
+* :ref:`fmt/core.h <core-api>`: the core API providing argument handling
+  facilities and a lightweight subset of formatting functions
+* :ref:`fmt/format.h <format-api>`: the full format API providing compile-time
+  format string checks, output iterator and user-defined type support
+* :ref:`fmt/time.h <time-api>`: date and time formatting
+* :ref:`fmt/ostream.h <ostream-api>`: ``std::ostream`` support
+* :ref:`fmt/printf.h <printf-api>`: ``printf`` formatting
+
+All functions and types provided by the library reside in namespace ``fmt`` and
+macros have prefix ``FMT_`` or ``fmt``.
+
+.. _core-api:
+
+Core API
+========
+
+``fmt/core.h`` defines the core API which provides argument handling facilities
+and a lightweight subset of formatting functions.
+
+The following functions use :ref:`format string syntax <syntax>`
+similar to that of Python's `str.format
+<http://docs.python.org/3/library/stdtypes.html#str.format>`_.
+They take *format_str* and *args* as arguments.
+
+*format_str* is a format string that contains literal text and replacement
+fields surrounded by braces ``{}``. The fields are replaced with formatted
+arguments in the resulting string. A function taking *format_str* doesn't
+participate in an overload resolution if the latter is not a string.
+
+*args* is an argument list representing objects to be formatted.
+
+.. _format:
+
+.. doxygenfunction:: format(const S&, const Args&...)
+.. doxygenfunction:: vformat(const S&, basic_format_args<typename buffer_context<Char>::type>)
+
+.. _print:
+
+.. doxygenfunction:: print(const S&, const Args&...)
+.. doxygenfunction:: vprint(string_view, format_args)
+
+.. doxygenfunction:: print(std::FILE *, const S&, const Args&...)
+.. doxygenfunction:: vprint(std::FILE *, string_view, format_args)
+.. doxygenfunction:: vprint(std::FILE *, wstring_view, wformat_args)
+
+Named arguments
+---------------
+
+.. doxygenfunction:: fmt::arg(string_view, const T&)
+
+Argument lists
+--------------
+
+.. doxygenfunction:: fmt::make_format_args(const Args&...)
+
+.. doxygenclass:: fmt::format_arg_store
+   :members:
+
+.. doxygenclass:: fmt::basic_format_args
+   :members:
+
+.. doxygenstruct:: fmt::format_args
+
+.. doxygenclass:: fmt::basic_format_arg
+   :members:
+
+Compatibility
+-------------
+
+.. doxygenclass:: fmt::basic_string_view
+   :members:
+
+.. doxygentypedef:: fmt::string_view
+.. doxygentypedef:: fmt::wstring_view
+
+.. _format-api:
+
+Format API
+==========
+
+``fmt/format.h`` defines the full format API providing compile-time format
+string checks, output iterator and user-defined type support.
+
+Compile-time format string checks
+---------------------------------
+
+.. doxygendefine:: fmt
+
+Formatting user-defined types
+-----------------------------
+
+To make a user-defined type formattable, specialize the ``formatter<T>`` struct
+template and implement ``parse`` and ``format`` methods::
+
+  #include <fmt/format.h>
+
+  struct point { double x, y; };
+
+  namespace fmt {
+  template <>
+  struct formatter<point> {
+    template <typename ParseContext>
+    constexpr auto parse(ParseContext &ctx) { return ctx.begin(); }
+
+    template <typename FormatContext>
+    auto format(const point &p, FormatContext &ctx) {
+      return format_to(ctx.begin(), "({:.1f}, {:.1f})", p.x, p.y);
+    }
+  };
+  }
+
+Then you can pass objects of type ``point`` to any formatting function::
+
+  point p = {1, 2};
+  std::string s = fmt::format("{}", p);
+  // s == "(1.0, 2.0)"
+
+In the example above the ``formatter<point>::parse`` function ignores the
+contents of the format string referred to by ``ctx.begin()`` so the object will
+always be formatted in the same way. See ``formatter<tm>::parse`` in
+:file:`fmt/time.h` for an advanced example of how to parse the format string and
+customize the formatted output.
+
+You can also reuse existing formatters, for example::
+
+  enum class color {red, green, blue};
+
+  template <>
+  struct fmt::formatter<color>: formatter<string_view> {
+    // parse is inherited from formatter<string_view>.
+    template <typename FormatContext>
+    auto format(color c, FormatContext &ctx) {
+      string_view name = "unknown";
+      switch (c) {
+      case color::red:   name = "red"; break;
+      case color::green: name = "green"; break;
+      case color::blue:  name = "blue"; break;
+      }
+      return formatter<string_view>::format(name, ctx);
+    }
+  };
+
+You can also write a formatter for a hierarchy of classes::
+
+  #include <type_traits>
+  #include <fmt/format.h>
+
+  struct A {
+    virtual ~A() {}
+    virtual std::string name() const { return "A"; }
+  };
+
+  struct B : A {
+    virtual std::string name() const { return "B"; }
+  };
+
+  template <typename T>
+  struct fmt::formatter<T, std::enable_if_t<std::is_base_of<A, T>::value, char>> :
+      fmt::formatter<std::string> {
+    template <typename FormatCtx>
+    auto format(const A& a, FormatCtx& ctx) {
+      return fmt::formatter<std::string>::format(a.name(), ctx);
+    }
+  };
+
+  int main() {
+    B b;
+    A& a = b;
+    fmt::print("{}", a); // prints "B"
+  }
+
+This section shows how to define a custom format function for a user-defined
+type. The next section describes how to get ``fmt`` to use a conventional stream
+output ``operator<<`` when one is defined for a user-defined type.
+
+Output iterator support
+-----------------------
+
+.. doxygenfunction:: fmt::format_to(OutputIt, const S &, const Args &...)
+.. doxygenfunction:: fmt::format_to_n(OutputIt, std::size_t, string_view, const Args&...)
+.. doxygenstruct:: fmt::format_to_n_result
+   :members:
+
+Literal-based API
+-----------------
+
+The following user-defined literals are defined in ``fmt/format.h``.
+
+.. doxygenfunction:: operator""_format(const char *, std::size_t)
+
+.. doxygenfunction:: operator""_a(const char *, std::size_t)
+
+Utilities
+---------
+
+.. doxygentypedef:: fmt::char_t
+
+.. doxygenfunction:: fmt::formatted_size(string_view, const Args&...)
+
+.. doxygenfunction:: fmt::to_string(const T&)
+
+.. doxygenfunction:: fmt::to_wstring(const T&)
+
+.. doxygenclass:: fmt::basic_memory_buffer
+   :protected-members:
+   :members:
+
+System errors
+-------------
+
+fmt does not use ``errno`` to communicate errors to the user, but it may call
+system functions which set ``errno``. Users should not make any assumptions about
+the value of ``errno`` being preserved by library functions.
+
+.. doxygenclass:: fmt::system_error
+   :members:
+
+.. doxygenfunction:: fmt::format_system_error
+
+.. doxygenclass:: fmt::windows_error
+   :members:
+
+.. _formatstrings:
+
+Custom allocators
+-----------------
+
+The {fmt} library supports custom dynamic memory allocators.
+A custom allocator class can be specified as a template argument to
+:class:`fmt::basic_memory_buffer`::
+
+    using custom_memory_buffer = 
+      fmt::basic_memory_buffer<char, fmt::inline_buffer_size, custom_allocator>;
+
+It is also possible to write a formatting function that uses a custom
+allocator::
+
+    using custom_string =
+      std::basic_string<char, std::char_traits<char>, custom_allocator>;
+
+    custom_string vformat(custom_allocator alloc, fmt::string_view format_str,
+                          fmt::format_args args) {
+      custom_memory_buffer buf(alloc);
+      fmt::vformat_to(buf, format_str, args);
+      return custom_string(buf.data(), buf.size(), alloc);
+    }
+
+    template <typename ...Args>
+    inline custom_string format(custom_allocator alloc,
+                                fmt::string_view format_str,
+                                const Args & ... args) {
+      return vformat(alloc, format_str, fmt::make_format_args(args...));
+    }
+
+The allocator will be used for the output container only. If you are using named
+arguments, the container that stores pointers to them will be allocated using
+the default allocator. Also floating-point formatting falls back on ``sprintf``
+which may do allocations.
+
+Custom formatting of built-in types
+-----------------------------------
+
+It is possible to change the way arguments are formatted by providing a
+custom argument formatter class::
+
+  using arg_formatter =
+    fmt::arg_formatter<fmt::back_insert_range<fmt::internal::buffer>>;
+
+  // A custom argument formatter that formats negative integers as unsigned
+  // with the ``x`` format specifier.
+  class custom_arg_formatter : public arg_formatter {
+   public:
+    custom_arg_formatter(fmt::format_context &ctx,
+                         fmt::format_specs *spec = nullptr)
+      : arg_formatter(ctx, spec) {}
+
+    using arg_formatter::operator();
+
+    auto operator()(int value) {
+      if (spec().type() == 'x')
+        return (*this)(static_cast<unsigned>(value)); // convert to unsigned and format
+      return arg_formatter::operator()(value);
+    }
+  };
+
+  std::string custom_vformat(fmt::string_view format_str, fmt::format_args args) {
+    fmt::memory_buffer buffer;
+    // Pass custom argument formatter as a template arg to vformat_to.
+    fmt::vformat_to<custom_arg_formatter>(buffer, format_str, args);
+    return fmt::to_string(buffer);
+  }
+
+  template <typename ...Args>
+  inline std::string custom_format(
+      fmt::string_view format_str, const Args &... args) {
+    return custom_vformat(format_str, fmt::make_format_args(args...));
+  }
+
+  std::string s = custom_format("{:x}", -42); // s == "ffffffd6"
+
+.. doxygenclass:: fmt::arg_formatter
+   :members:
+
+.. _time-api:
+
+Date and time formatting
+========================
+
+The library supports `strftime
+<http://en.cppreference.com/w/cpp/chrono/c/strftime>`_-like date and time
+formatting::
+
+  #include <fmt/time.h>
+
+  std::time_t t = std::time(nullptr);
+  // Prints "The date is 2016-04-29." (with the current date)
+  fmt::print("The date is {:%Y-%m-%d}.", *std::localtime(&t));
+
+The format string syntax is described in the documentation of
+`strftime <http://en.cppreference.com/w/cpp/chrono/c/strftime>`_.
+
+.. _ostream-api:
+
+``std::ostream`` support
+========================
+
+``fmt/ostream.h`` provides ``std::ostream`` support including formatting of
+user-defined types that have overloaded ``operator<<``::
+
+  #include <fmt/ostream.h>
+
+  class date {
+    int year_, month_, day_;
+  public:
+    date(int year, int month, int day): year_(year), month_(month), day_(day) {}
+
+    friend std::ostream &operator<<(std::ostream &os, const date &d) {
+      return os << d.year_ << '-' << d.month_ << '-' << d.day_;
+    }
+  };
+
+  std::string s = fmt::format("The date is {}", date(2012, 12, 9));
+  // s == "The date is 2012-12-9"
+
+.. doxygenfunction:: print(std::basic_ostream<fmt::char_t<S>>&, const S&, const Args&...)
+
+.. _printf-api:
+
+``printf`` formatting
+=====================
+
+The header ``fmt/printf.h`` provides ``printf``-like formatting functionality.
+The following functions use `printf format string syntax
+<http://pubs.opengroup.org/onlinepubs/009695399/functions/fprintf.html>`_ with
+the POSIX extension for positional arguments. Unlike their standard
+counterparts, the ``fmt`` functions are type-safe and throw an exception if an
+argument type doesn't match its format specification.
+
+.. doxygenfunction:: printf(const S&, const Args&...)
+
+.. doxygenfunction:: fprintf(std::FILE *, const S&, const Args&...)
+
+.. doxygenfunction:: fprintf(std::basic_ostream<fmt::char_t<S>>&, const S&, const Args&...)
+
+.. doxygenfunction:: sprintf(const S&, const Args&...)