| //===- Format.h - Efficient printf-style formatting for streams -*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements the format() function, which can be used with other |
| // LLVM subsystems to provide printf-style formatting. This gives all the power |
| // and risk of printf. This can be used like this (with raw_ostreams as an |
| // example): |
| // |
| // OS << "mynumber: " << format("%4.5f", 1234.412) << '\n'; |
| // |
| // Or if you prefer: |
| // |
| // OS << format("mynumber: %4.5f\n", 1234.412); |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_SUPPORT_FORMAT_H |
| #define LLVM_SUPPORT_FORMAT_H |
| |
| #include "llvm/ADT/STLExtras.h" |
| #include "llvm/ADT/StringRef.h" |
| #include "llvm/Support/DataTypes.h" |
| #include <cassert> |
| #include <cstdio> |
| #include <tuple> |
| |
| namespace llvm { |
| |
| /// This is a helper class used for handling formatted output. It is the |
| /// abstract base class of a templated derived class. |
| class format_object_base { |
| protected: |
| const char *Fmt; |
| ~format_object_base() = default; // Disallow polymorphic deletion. |
| format_object_base(const format_object_base &) = default; |
| virtual void home(); // Out of line virtual method. |
| |
| /// Call snprintf() for this object, on the given buffer and size. |
| virtual int snprint(char *Buffer, unsigned BufferSize) const = 0; |
| |
| public: |
| format_object_base(const char *fmt) : Fmt(fmt) {} |
| |
| /// Format the object into the specified buffer. On success, this returns |
| /// the length of the formatted string. If the buffer is too small, this |
| /// returns a length to retry with, which will be larger than BufferSize. |
| unsigned print(char *Buffer, unsigned BufferSize) const { |
| assert(BufferSize && "Invalid buffer size!"); |
| |
| // Print the string, leaving room for the terminating null. |
| int N = snprint(Buffer, BufferSize); |
| |
| // VC++ and old GlibC return negative on overflow, just double the size. |
| if (N < 0) |
| return BufferSize * 2; |
| |
| // Other implementations yield number of bytes needed, not including the |
| // final '\0'. |
| if (unsigned(N) >= BufferSize) |
| return N + 1; |
| |
| // Otherwise N is the length of output (not including the final '\0'). |
| return N; |
| } |
| }; |
| |
| /// These are templated helper classes used by the format function that |
| /// capture the object to be formated and the format string. When actually |
| /// printed, this synthesizes the string into a temporary buffer provided and |
| /// returns whether or not it is big enough. |
| |
| template <typename... Ts> |
| class format_object final : public format_object_base { |
| std::tuple<Ts...> Vals; |
| |
| template <std::size_t... Is> |
| int snprint_tuple(char *Buffer, unsigned BufferSize, |
| index_sequence<Is...>) const { |
| #ifdef _MSC_VER |
| return _snprintf(Buffer, BufferSize, Fmt, std::get<Is>(Vals)...); |
| #else |
| return snprintf(Buffer, BufferSize, Fmt, std::get<Is>(Vals)...); |
| #endif |
| } |
| |
| public: |
| format_object(const char *fmt, const Ts &... vals) |
| : format_object_base(fmt), Vals(vals...) {} |
| |
| int snprint(char *Buffer, unsigned BufferSize) const override { |
| return snprint_tuple(Buffer, BufferSize, index_sequence_for<Ts...>()); |
| } |
| }; |
| |
| /// These are helper functions used to produce formatted output. They use |
| /// template type deduction to construct the appropriate instance of the |
| /// format_object class to simplify their construction. |
| /// |
| /// This is typically used like: |
| /// \code |
| /// OS << format("%0.4f", myfloat) << '\n'; |
| /// \endcode |
| |
| template <typename... Ts> |
| inline format_object<Ts...> format(const char *Fmt, const Ts &... Vals) { |
| return format_object<Ts...>(Fmt, Vals...); |
| } |
| |
| /// This is a helper class used for left_justify() and right_justify(). |
| class FormattedString { |
| StringRef Str; |
| unsigned Width; |
| bool RightJustify; |
| friend class raw_ostream; |
| |
| public: |
| FormattedString(StringRef S, unsigned W, bool R) |
| : Str(S), Width(W), RightJustify(R) { } |
| }; |
| |
| /// left_justify - append spaces after string so total output is |
| /// \p Width characters. If \p Str is larger that \p Width, full string |
| /// is written with no padding. |
| inline FormattedString left_justify(StringRef Str, unsigned Width) { |
| return FormattedString(Str, Width, false); |
| } |
| |
| /// right_justify - add spaces before string so total output is |
| /// \p Width characters. If \p Str is larger that \p Width, full string |
| /// is written with no padding. |
| inline FormattedString right_justify(StringRef Str, unsigned Width) { |
| return FormattedString(Str, Width, true); |
| } |
| |
| /// This is a helper class used for format_hex() and format_decimal(). |
| class FormattedNumber { |
| uint64_t HexValue; |
| int64_t DecValue; |
| unsigned Width; |
| bool Hex; |
| bool Upper; |
| bool HexPrefix; |
| friend class raw_ostream; |
| |
| public: |
| FormattedNumber(uint64_t HV, int64_t DV, unsigned W, bool H, bool U, |
| bool Prefix) |
| : HexValue(HV), DecValue(DV), Width(W), Hex(H), Upper(U), |
| HexPrefix(Prefix) {} |
| }; |
| |
| /// format_hex - Output \p N as a fixed width hexadecimal. If number will not |
| /// fit in width, full number is still printed. Examples: |
| /// OS << format_hex(255, 4) => 0xff |
| /// OS << format_hex(255, 4, true) => 0xFF |
| /// OS << format_hex(255, 6) => 0x00ff |
| /// OS << format_hex(255, 2) => 0xff |
| inline FormattedNumber format_hex(uint64_t N, unsigned Width, |
| bool Upper = false) { |
| assert(Width <= 18 && "hex width must be <= 18"); |
| return FormattedNumber(N, 0, Width, true, Upper, true); |
| } |
| |
| /// format_hex_no_prefix - Output \p N as a fixed width hexadecimal. Does not |
| /// prepend '0x' to the outputted string. If number will not fit in width, |
| /// full number is still printed. Examples: |
| /// OS << format_hex_no_prefix(255, 2) => ff |
| /// OS << format_hex_no_prefix(255, 2, true) => FF |
| /// OS << format_hex_no_prefix(255, 4) => 00ff |
| /// OS << format_hex_no_prefix(255, 1) => ff |
| inline FormattedNumber format_hex_no_prefix(uint64_t N, unsigned Width, |
| bool Upper = false) { |
| assert(Width <= 16 && "hex width must be <= 16"); |
| return FormattedNumber(N, 0, Width, true, Upper, false); |
| } |
| |
| /// format_decimal - Output \p N as a right justified, fixed-width decimal. If |
| /// number will not fit in width, full number is still printed. Examples: |
| /// OS << format_decimal(0, 5) => " 0" |
| /// OS << format_decimal(255, 5) => " 255" |
| /// OS << format_decimal(-1, 3) => " -1" |
| /// OS << format_decimal(12345, 3) => "12345" |
| inline FormattedNumber format_decimal(int64_t N, unsigned Width) { |
| return FormattedNumber(0, N, Width, false, false, false); |
| } |
| |
| } // end namespace llvm |
| |
| #endif |