Merge pull request 'feature/int_hex' (#6) from feature/int_hex into master

Reviewed-on: http://git.mercurial-manifold.eu/an.tsouchlos/const_fmt/pulls/6

.gitignore

@@ -1,3 +1,4 @@
+build
 cmake-build-debug
 cmake-build-release
 .idea

CMakeLists.txt

@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.21)
-project(logger)
+project(const_fmt)
 
 set(CMAKE_CXX_STANDARD 20)
 
@@ -9,16 +9,10 @@ if(NOT CMAKE_BUILD_TYPE)
 endif()
 
 
-include_directories(inc)
-
-add_executable(logger src/main.cpp)
+include_directories(.)
 
 
-if(MSVC)
-    target_compile_options(logger PRIVATE /W4 /WX)
-else()
-    target_compile_options(logger PRIVATE -O3 -Wall -Wextra -pedantic -fno-exceptions)
-endif()
+add_subdirectory(examples)
 
 
 option(PACKAGE_TESTS "Build the tests" ON)

LICENSE

@@ -0,0 +1,19 @@
+Copyright 2022 Andreas Tsouchlos
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -0,0 +1,55 @@
+# const_fmt
+
+An extremely lightweight library, intentionally resembling `fmtlib` as much as possible. This is achieved by moving
+as much of the formatting process as possible to compile time.
+
+Meant for systems with very few resources, such as embedded systems.
+
+## Overview
+
+During compile-time, the string to be formatted is preprocessed to the point only the actual values to be formatted
+have to be written (If they are not available at compile time).
+
+For example `One number: {:03}; And another one: {:05.3}` is preprocessed into `One number: 000; And another one: 00.000`.
+This is returned as a `std::array<char, N>`, where `N` is automatically evaluated. The only code executed at compile
+time then formats the numbers and writes them into their place in the array.
+
+Disclaimer: The actual formatting code is largely shamelessly stolen from `fmtlib`.
+
+## Including in a project
+
+In order to keep it as lightweight and optimizable as possible, `const_fmt` is implemented as a header-only
+library.
+
+This means that using it in a project is as simple as cloning this repo (or e.g. adding it as a submodule)
+and adding the repository root folder to the compiler include directories.
+
+## Building and running the tests
+
+1. Initialize the `googletest` framework submodule
+```bash
+$ git submodule update --init
+```
+
+2. Create the build directory
+```bash
+$ cmake -B build -S .
+```
+
+3. Build the project
+```bash
+$ cmake --build build/
+```
+
+4. Run the tests
+```bash
+$ ctest --test-dir build/
+```
+
+## Limitations
+
+Only a relatively limited subset of the `fmtlib` syntax is recognized (for now anyway). In particular,
+there is no support for positional arguments, alignment, chrono format specs and custom const_format specifications.
+
+By nature of the library design, which forces compile-time preprocessing of the const_format string, no dynamic width or
+dynamic precision can be implemented.

const_fmt/format.h

@@ -2,14 +2,12 @@
 #define LOGGER_FORMAT_H
 
 
-#include <cstring>
-
+#include "format_impl.h"
 #include "parse.h"
 #include "utility.h"
-#include "format_impl.h"
 
 
-namespace detail {
+namespace const_fmt { namespace const_fmt_detail {
 
 
 /*
@@ -22,7 +20,7 @@ namespace detail {
 template <ConstString s>
 constexpr inline int get_output_len() {
     constexpr auto parse_result = parse_string<s>();
-    static_assert(parse_result.is_valid, "Syntax error in format string");
+    static_assert(parse_result.is_valid, "Syntax error in const_format string");
 
     return get_ast_output_len<parse_result.value>();
 }
@@ -42,16 +40,16 @@ constexpr inline void check_fmt_params() {
 
 template <fmt_data_t fmt_data, std::integral arg_t>
 constexpr inline void format_arg(char* dest, arg_t arg) {
-    detail::format_int(dest, arg, fmt_data);
+    const_fmt_detail::format_int<fmt_data>(dest, arg);
 };
 
 template <fmt_data_t fmt_data, std::floating_point arg_t>
-constexpr inline void format_arg(char* dest, arg_t arg) {
-    //detail::format_float(dest, arg, fmt_data);
+constexpr inline void format_arg(char* dest, arg_t arg){
+    const_fmt_detail::format_float<fmt_data>(dest, arg);
 };
 
 // TODO: Error handling
-template<fmt_data_t fmt_data>
+template <fmt_data_t fmt_data>
 constexpr inline void format_arg(char* dest, const char* arg) {
     const std::size_t len = const_strlen(arg);
     if (len > fmt_data.length) return;
@@ -74,30 +72,33 @@ constexpr inline void format_args(char*) {
 }
 
 template <auto fmt_data_array, typename first_arg_t, typename... args_t>
-constexpr inline void format_args(char* dest, first_arg_t first_arg, args_t... args) {
+constexpr inline void format_args(char* dest, first_arg_t first_arg,
+                                  args_t... args) {
     format_arg<fmt_data_array[0]>(dest + fmt_data_array[0].position, first_arg);
     format_args<drop_first(fmt_data_array)>(dest, args...);
 }
 
 
 template <auto ast>
-consteval inline std::array<char, get_ast_output_len<ast>()> get_preproc_string() {
-    auto result = get_init_array<get_ast_output_len<ast>()>('f');
+consteval inline auto get_preproc_string() {
+    std::array<char, get_ast_output_len<ast>()> result;
 
     int i = 0;
 
     for (const auto& ast_node : ast) {
-        if (ast_node.is_char())
+        if (ast_node.is_char()) {
             result[i++] = ast_node.get_char();
-        else
-            i += ast_node.get_node().length;
+        } else {
+            for (int j = 0; j < ast_node.get_node().length; ++j)
+                result[i++] = ast_node.get_node().has_zero_padding ? '0' : ' ';
+        }
     }
 
     return result;
 }
 
 
-} // namespace detail
+}} // namespace const_fmt::const_fmt_detail
 
 
 /*
@@ -107,32 +108,40 @@ consteval inline std::array<char, get_ast_output_len<ast>()> get_preproc_string(
  */
 
 
-template <detail::ConstString s, typename... args_t>
-constexpr inline auto format(args_t... args) {
-    constexpr auto ast      = detail::parse_string<s>().value;
-    constexpr auto fmt_data = detail::get_fmt_data<ast>();
+namespace const_fmt {
 
-    auto result = detail::get_preproc_string<ast>();
 
-    detail::format_args<fmt_data>(result.begin(), args...);
+template <const_fmt_detail::ConstString s, typename... args_t>
+constexpr inline auto const_format(args_t... args) {
+    constexpr auto ast      = const_fmt_detail::parse_string<s>();
+    constexpr auto fmt_data = const_fmt_detail::get_fmt_data<ast.value>();
+
+    static_assert(ast.is_valid, "Invalid format string");
+
+    auto result = const_fmt_detail::get_preproc_string<ast.value>();
+
+    const_fmt_detail::format_args<fmt_data>(result.begin(), args...);
 
     return result;
 }
 
 
-template<detail::ConstString t_s>
-class fmt_literal_obj_t {
-    public:
-        template<typename... args_t>
-        constexpr auto operator()(args_t... args) {
-            return format<t_s>(args...);
-        }
+template <const_fmt_detail::ConstString t_s>
+class const_fmt_literal_obj_t {
+public:
+    template <typename... args_t>
+    constexpr auto operator()(args_t... args) {
+        return const_format<t_s>(args...);
+    }
 };
 
-template <detail::ConstString t_s>
-constexpr auto operator""_fmt() {
-    return fmt_literal_obj_t<t_s>{};
+template <const_fmt_detail::ConstString t_s>
+constexpr auto operator""_const_fmt() {
+    return const_fmt_literal_obj_t<t_s>{};
 }
 
 
+} // namespace const_fmt
+
+
 #endif // LOGGER_FORMAT_H

const_fmt/format_impl.h

@@ -0,0 +1,270 @@
+#ifndef LOGGER_FORMAT_IMPL_H
+#define LOGGER_FORMAT_IMPL_H
+
+
+/*
+ *
+ * ****************************************************************
+ * Disclaimer: Most of this code is shamelessly stolen from fmtlib
+ * ****************************************************************
+ *
+ */
+
+#include <stdint.h>
+
+#include "utility.h"
+
+
+namespace const_fmt { namespace const_fmt_detail {
+
+
+/*
+ *
+ * Utility functions
+ *
+ */
+
+
+#define FMT_POWERS_OF_10(factor)                                               \
+    factor * 10, (factor)*100, (factor)*1000, (factor)*10000, (factor)*100000, \
+        (factor)*1000000, (factor)*10000000, (factor)*100000000,               \
+        (factor)*1000000000
+
+template <typename T>
+constexpr int count_digits_decimal_fallback(T n) {
+    int count = 1;
+    for (;;) {
+        if (n < 10) return count;
+        if (n < 100) return count + 1;
+        if (n < 1000) return count + 2;
+        if (n < 10000) return count + 3;
+        n /= 10000u;
+        count += 4;
+    }
+}
+
+inline int do_count_digits_decimal(uint64_t n) {
+    // Maps bsr(n) to ceil(log10(pow(2, bsr(n) + 1) - 1)).
+    static constexpr uint8_t bsr2log10[] = {
+        1,  1,  1,  2,  2,  2,  3,  3,  3,  4,  4,  4,  4,  5,  5,  5,
+        6,  6,  6,  7,  7,  7,  7,  8,  8,  8,  9,  9,  9,  10, 10, 10,
+        10, 11, 11, 11, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 15, 15,
+        15, 16, 16, 16, 16, 17, 17, 17, 18, 18, 18, 19, 19, 19, 19, 20};
+    auto                            t = bsr2log10[__builtin_clzll(n | 1) ^ 63];
+    static constexpr const uint64_t zero_or_powers_of_10[] = {
+        0, 0, FMT_POWERS_OF_10(1U), FMT_POWERS_OF_10(1000000000ULL),
+        10000000000000000000ULL};
+    return t - (n < zero_or_powers_of_10[t]);
+}
+
+template <FormatType t_format_type>
+constexpr inline auto count_digits_base(uint64_t n) -> int {
+    if constexpr (t_format_type == FormatType::b) {
+        int result = 0;
+
+        while (n) {
+            n = n >> 1;
+            result += 1;
+        }
+
+        return result;
+    } else {
+        if constexpr (t_format_type == FormatType::x) {
+            int result = 0;
+
+            while (n) {
+                n = n >> 4;
+                result += 1;
+            }
+
+            return (result + count_digits_base<FormatType::b>(n));
+        } else {
+            if (!std::is_constant_evaluated()) {
+                return do_count_digits_decimal(n);
+            }
+            return count_digits_decimal_fallback(n);
+        }
+    }
+}
+
+
+// Converts value in the range [0, base^2) to a string.
+template <FormatType t_format_type>
+constexpr inline const char* digits2_base(size_t value) {
+    // GCC generates slightly better code when value is pointer-size.
+    if constexpr (t_format_type == FormatType::b) {
+        return &"00011011"[value * 2];
+    } else {
+        if constexpr (t_format_type == FormatType::x) {
+            // clang-format off
+            return &"000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F"
+                    "202122232425262728292A2B2C2D2E2F303132333435363738393A3B3C3D3E3F"
+                    "404142434445464748494A4B4C4D4E4F505152535455565758595A5B5C5D5E5F"
+                    "606162636465666768696A6B6C6D6E6F707172737475767778797A7B7C7D7E7F"
+                    "808182838485868788898A8B8C8D8E8F909192939495969798999A9B9C9D9E9F"
+                    "A0A1A2A3A4A5A6A7A8A9AAABACADAEAFB0B1B2B3B4B5B6B7B8B9BABBBCBDBEBF"
+                    "C0C1C2C3C4C5C6C7C8C9CACBCCCDCECFD0D1D2D3D4D5D6D7D8D9DADBDCDDDEDF"
+                    "E0E1E2E3E4E5E6E7E8E9EAEBECEDEEEFF0F1F2F3F4F5F6F7F8F9FAFBFCFDFEFF"[value * 2];
+            // clang-format on
+        } else {
+            return &"0001020304050607080910111213141516171819"
+                    "2021222324252627282930313233343536373839"
+                    "4041424344454647484950515253545556575859"
+                    "6061626364656667686970717273747576777879"
+                    "8081828384858687888990919293949596979899"[value * 2];
+        }
+    }
+}
+
+
+constexpr inline void copy2(char* dst, const char* src) {
+    if (!std::is_constant_evaluated()) {
+        std::memcpy(dst, src, 2);
+        return;
+    }
+    *dst++ = static_cast<char>(*src++);
+    *dst   = static_cast<char>(*src);
+}
+
+template <FormatType t_format_type>
+consteval inline unsigned get_base_divisor() {
+    switch (t_format_type) {
+    case FormatType::b:
+        return 2;
+    case FormatType::x:
+        return 16;
+    default:
+        return 10;
+    }
+}
+
+template <FormatType t_format_type, typename uint_t>
+constexpr inline void format_base(char* out, uint_t value, int n_digits,
+                                  int size) {
+    constexpr unsigned divisor        = get_base_divisor<t_format_type>();
+    constexpr unsigned square_divisor = const_pow(divisor, 2);
+
+    if (n_digits > size) {
+        for (int i = 0; i < size; ++i) {
+            *(out++) = 'f';
+        }
+        return;
+    }
+
+    out += size;
+    while (value >= square_divisor) {
+        out -= 2;
+        copy2(out, digits2_base<t_format_type>(
+                       static_cast<size_t>(value % square_divisor)));
+        value /= square_divisor;
+    }
+
+    if (value < divisor) {
+        *--out = digits2_base<t_format_type>(value*divisor)[0];
+        return;
+    }
+
+    out -= 2;
+    copy2(out, digits2_base<t_format_type>(static_cast<size_t>(value)));
+}
+
+
+// returns {abs_value, was_negative}
+template <std::signed_integral int_t>
+constexpr std::pair<typename std::make_unsigned<int_t>::type, bool>
+get_abs_value(int_t value) {
+    using uint_t = typename std::make_unsigned<int_t>::type;
+
+    uint_t abs_value = static_cast<uint_t>(value);
+
+    const bool negative = value < 0;
+    if (negative) abs_value = 0 - abs_value;
+
+    return {abs_value, negative};
+}
+
+template <std::unsigned_integral int_t>
+constexpr std::pair<int_t, bool> get_abs_value(int_t value) {
+    return {value, false};
+}
+
+
+/*
+ *
+ * Integral types
+ *
+ */
+
+
+template <fmt_data_t t_fmt_node, std::unsigned_integral uint_t>
+constexpr inline void format_int(char* out, uint_t value) {
+    format_base<t_fmt_node.type>(out, value,
+                                 count_digits_base<t_fmt_node.type>(value),
+                                 t_fmt_node.length);
+}
+
+
+template <fmt_data_t t_fmt_node, std::signed_integral int_t>
+constexpr inline void format_int(char* out, int_t value) {
+    const auto [abs_value, negative] = get_abs_value(value);
+
+    const std::size_t n_digits = count_digits_base<t_fmt_node.type>(abs_value);
+
+    format_base<t_fmt_node.type>(out + 1 * (negative), abs_value, n_digits,
+                                 t_fmt_node.length - 1 * (negative));
+
+    if constexpr (t_fmt_node.has_zero_padding) {
+        if (negative) *(out) = '-';
+    } else {
+        if (n_digits < t_fmt_node.length)
+            if (negative) *(out + t_fmt_node.length - n_digits - 1) = '-';
+    }
+}
+
+
+/*
+ *
+ * Floating point types
+ *
+ */
+
+
+template <fmt_data_t t_fmt_node, std::floating_point float_t>
+constexpr inline void format_float(char* out, float_t value) {
+    // clang-format off
+    constexpr fmt_data_t fmt_node_integral = {
+        t_fmt_node.has_zero_padding,                  // has_zero_padding
+        t_fmt_node.length - t_fmt_node.precision - 1, // length
+        t_fmt_node.precision,                         // ignored
+        FormatType::d,                                // type
+        t_fmt_node.position                           // ignored
+    };
+    constexpr fmt_data_t fmt_node_fractional = {
+        true,                                         // has_zero_padding
+        t_fmt_node.precision,                         // length
+        t_fmt_node.precision,                         // ignored
+        FormatType::d,                                // type
+        t_fmt_node.position                           // ignored
+    };
+    // clang-format on
+
+    *(out + t_fmt_node.length - t_fmt_node.precision - 1) = '.';
+
+    const int integral = static_cast<int>(value);
+
+    constexpr std::size_t factor = const_pow(10, t_fmt_node.precision);
+    const int fractional = static_cast<int>((value - integral) * factor);
+
+    const auto [fractional_abs, fractional_negative] =
+        get_abs_value(fractional);
+
+    format_int<fmt_node_integral, int>(out, integral);
+    format_int<fmt_node_fractional, uint16_t>(
+        out + t_fmt_node.length - t_fmt_node.precision, fractional_abs);
+}
+
+
+}} // namespace const_fmt::const_fmt_detail
+
+
+#endif // LOGGER_FORMAT_IMPL_H

const_fmt/parse.h

@@ -5,7 +5,7 @@
 #include "types.h"
 
 
-// clang-format off
+// clang-const_format off
 
 /*
  *
@@ -34,10 +34,10 @@
  *
  */
 
-// clang-format on
+// clang-const_format on
 
 
-namespace detail {
+namespace const_fmt { namespace const_fmt_detail {
 
 
 /*
@@ -119,42 +119,42 @@ constexpr inline parse_result_t<unsigned> parse_number(unsigned i) {
 template <ConstString s>
 constexpr inline parse_result_t<FormatType> parse_type(unsigned i) {
     switch (s[i]) {
-        case 's':
-            return {true, ++i, FormatType::s};
-        case 'c':
-            return {true, ++i, FormatType::c};
-        case 'b':
-            return {true, ++i, FormatType::b};
-        case 'B':
-            return {true, ++i, FormatType::B};
-        case 'd':
-            return {true, ++i, FormatType::d};
-        case 'o':
-            return {true, ++i, FormatType::o};
-        case 'x':
-            return {true, ++i, FormatType::x};
-        case 'X':
-            return {true, ++i, FormatType::X};
-        case 'a':
-            return {true, ++i, FormatType::a};
-        case 'A':
-            return {true, ++i, FormatType::A};
-        case 'e':
-            return {true, ++i, FormatType::e};
-        case 'E':
-            return {true, ++i, FormatType::E};
-        case 'f':
-            return {true, ++i, FormatType::f};
-        case 'F':
-            return {true, ++i, FormatType::F};
-        case 'g':
-            return {true, ++i, FormatType::g};
-        case 'G':
-            return {true, ++i, FormatType::G};
-        case 'p':
-            return {true, ++i, FormatType::p};
-        default:
-            return {false, i, FormatType::s};
+    case 's':
+        return {true, ++i, FormatType::s};
+    case 'c':
+        return {true, ++i, FormatType::c};
+    case 'b':
+        return {true, ++i, FormatType::b};
+    case 'B':
+        return {true, ++i, FormatType::B};
+    case 'd':
+        return {true, ++i, FormatType::d};
+    case 'o':
+        return {true, ++i, FormatType::o};
+    case 'x':
+        return {true, ++i, FormatType::x};
+    case 'X':
+        return {true, ++i, FormatType::X};
+    case 'a':
+        return {true, ++i, FormatType::a};
+    case 'A':
+        return {true, ++i, FormatType::A};
+    case 'e':
+        return {true, ++i, FormatType::e};
+    case 'E':
+        return {true, ++i, FormatType::E};
+    case 'f':
+        return {true, ++i, FormatType::f};
+    case 'F':
+        return {true, ++i, FormatType::F};
+    case 'g':
+        return {true, ++i, FormatType::g};
+    case 'G':
+        return {true, ++i, FormatType::G};
+    case 'p':
+        return {true, ++i, FormatType::p};
+    default:
+        return {false, i, FormatType::s};
     }
 }
 
@@ -214,7 +214,8 @@ constexpr inline parse_result_t<fmt_node_t> parse_braces(unsigned i) {
 }
 
 template <ConstString s>
-constexpr inline parse_result_t<string_result_t<get_ast_len<s>()>> parse_string() {
+constexpr inline parse_result_t<string_result_t<get_ast_len<s>()>>
+parse_string() {
     parse_result_t<string_result_t<get_ast_len<s>()>> result;
     result.is_valid = true;
 
@@ -242,7 +243,7 @@ constexpr inline parse_result_t<string_result_t<get_ast_len<s>()>> parse_string(
 }
 
 
-} // namespace detail
+}} // namespace const_fmt::const_fmt_detail
 
 
 

const_fmt/types.h

@@ -5,7 +5,7 @@
 #include <array>
 
 
-namespace detail {
+namespace const_fmt { namespace const_fmt_detail {
 
 
 /*
@@ -136,7 +136,7 @@ struct fmt_data_t {
 };
 
 
-} // namespace detail
+}} // namespace const_fmt::const_fmt_detail
 
 
 #endif // LOGGER_TYPES_H

const_fmt/utility.h

@@ -7,7 +7,7 @@
 #include "types.h"
 
 
-namespace detail {
+namespace const_fmt { namespace const_fmt_detail {
 
 
 constexpr inline std::size_t const_pow(std::size_t base, std::size_t pow) {
@@ -18,17 +18,6 @@ constexpr inline std::size_t const_pow(std::size_t base, std::size_t pow) {
 }
 
 
-template <std::size_t t_n>
-consteval inline std::array<char, t_n> get_init_array(char val) {
-    std::array<char, t_n> result;
-
-    for (auto& c : result)
-        c = val;
-
-    return result;
-}
-
-
 template <auto ast>
 consteval inline std::size_t count_ast_format_nodes() {
     std::size_t result = 0;
@@ -41,7 +30,8 @@ consteval inline std::size_t count_ast_format_nodes() {
 
 
 template <auto ast>
-consteval inline std::array<fmt_data_t, count_ast_format_nodes<ast>()> get_fmt_data() {
+consteval inline std::array<fmt_data_t, count_ast_format_nodes<ast>()>
+get_fmt_data() {
     std::array<fmt_data_t, count_ast_format_nodes<ast>()> result = {};
 
     std::size_t position = 0;
@@ -96,7 +86,7 @@ consteval inline int get_ast_output_len() {
     return result;
 }
 
-constexpr inline  std::size_t const_strlen(const char* arg) {
+constexpr inline std::size_t const_strlen(const char* arg) {
     if (std::is_constant_evaluated()) {
         return *arg ? 1 + const_strlen(arg + 1) : 0;
     } else {
@@ -105,7 +95,7 @@ constexpr inline  std::size_t const_strlen(const char* arg) {
 }
 
 
-} // namespace detail
+}} // namespace const_fmt::const_fmt_detail
 
 
 #endif // LOGGER_UTILITY_H

examples/CMakeLists.txt

@@ -0,0 +1,7 @@
+add_executable(const_fmt_example src/examples.cpp)
+
+if(MSVC)
+    target_compile_options(const_fmt_example PRIVATE /W4 /WX)
+else()
+    target_compile_options(const_fmt_example PRIVATE -O3 -Wall -Wextra -pedantic -fno-exceptions)
+endif()

examples/src/examples.cpp

@@ -0,0 +1,17 @@
+#include <const_fmt/format.h>
+#include <iostream>
+#include <string_view>
+
+using namespace const_fmt;
+
+int main() {
+    constexpr auto s = "This is an integer: {:08x}, and this is a float: {:09.4b}"_const_fmt(122u, -86.2);
+
+    // Convert s (with a type of 'std::array<char, N>') into something
+    // writable to std::cout
+    std::string_view sv{&s[0], s.size()};
+
+    std::cout << sv << std::endl;
+
+    return 0;
+}

inc/Logger.h

@@ -1,52 +0,0 @@
-#ifndef LOGGER_LOGGER_H
-#define LOGGER_LOGGER_H
-
-
-#include <array>
-#include <iostream>
-#include <tuple>
-
-#include <format.h>
-
-
-/*
- *
- * Logger class
- *
- */
-
-
-namespace detail {
-
-template <typename T>
-concept output_policy_c = requires(T t) {
-    t.write('c');
-};
-
-} // namespace detail
-
-
-template <detail::output_policy_c output_policy_t>
-class Logger {
-
-public:
-    Logger(output_policy_t output_policy) : m_output_policy(output_policy) {
-    }
-
-    template <detail::ConstString msg, typename... args_t>
-    void log(args_t... args) {
-        const auto formatted_msg = format<msg>(args...);
-
-        for (const auto& c : formatted_msg) {
-            m_output_policy.write(c);
-        }
-
-        m_output_policy.write('\n');
-    }
-
-private:
-    output_policy_t& m_output_policy;
-};
-
-
-#endif // LOGGER_LOGGER_H

inc/format_impl.h

@@ -1,154 +0,0 @@
-#ifndef LOGGER_FORMAT_IMPL_H
-#define LOGGER_FORMAT_IMPL_H
-
-
-/*
- *
- * ****************************************************************
- * Disclaimer: Most of this code is shamelessly stolen from fmtlib
- * ****************************************************************
- *
- */
-
-
-#include <cstdint>
-
-#include "utility.h"
-
-
-namespace detail {
-
-
-/*
- *
- * Utility functions
- *
- */
-
-
-#define FMT_POWERS_OF_10(factor)                                               \
-    factor * 10, (factor)*100, (factor)*1000, (factor)*10000, (factor)*100000, \
-        (factor)*1000000, (factor)*10000000, (factor)*100000000,               \
-        (factor)*1000000000
-
-template <typename T>
-constexpr int count_digits_fallback(T n) {
-    int count = 1;
-    for (;;) {
-        if (n < 10) return count;
-        if (n < 100) return count + 1;
-        if (n < 1000) return count + 2;
-        if (n < 10000) return count + 3;
-        n /= 10000u;
-        count += 4;
-    }
-}
-
-inline int do_count_digits(uint64_t n) {
-    // Maps bsr(n) to ceil(log10(pow(2, bsr(n) + 1) - 1)).
-    static constexpr uint8_t bsr2log10[] = {
-        1,  1,  1,  2,  2,  2,  3,  3,  3,  4,  4,  4,  4,  5,  5,  5,
-        6,  6,  6,  7,  7,  7,  7,  8,  8,  8,  9,  9,  9,  10, 10, 10,
-        10, 11, 11, 11, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 15, 15,
-        15, 16, 16, 16, 16, 17, 17, 17, 18, 18, 18, 19, 19, 19, 19, 20};
-    auto                            t = bsr2log10[__builtin_clzll(n | 1) ^ 63];
-    static constexpr const uint64_t zero_or_powers_of_10[] = {
-        0, 0, FMT_POWERS_OF_10(1U), FMT_POWERS_OF_10(1000000000ULL),
-        10000000000000000000ULL};
-    return t - (n < zero_or_powers_of_10[t]);
-}
-
-constexpr inline auto count_digits(uint64_t n) -> int {
-    if (!std::is_constant_evaluated()) {
-        return do_count_digits(n);
-    }
-    return count_digits_fallback(n);
-}
-
-
-// Converts value in the range [0, 100) to a string.
-constexpr inline const char* digits2(size_t value) {
-    // GCC generates slightly better code when value is pointer-size.
-    return &"0001020304050607080910111213141516171819"
-            "2021222324252627282930313233343536373839"
-            "4041424344454647484950515253545556575859"
-            "6061626364656667686970717273747576777879"
-            "8081828384858687888990919293949596979899"[value * 2];
-}
-
-
-constexpr inline void copy2(char* dst, const char* src) {
-    if (!std::is_constant_evaluated()) {
-        std::memcpy(dst, src, 2);
-        return;
-    }
-    *dst++ = static_cast<char>(*src++);
-    *dst   = static_cast<char>(*src);
-}
-
-template <typename uint_t>
-constexpr inline void format_decimal(char* out, uint_t value, int size) {
-    if (count_digits(value) > size) return;
-
-    out += size;
-    while (value >= 100) {
-        out -= 2;
-        copy2(out, digits2(static_cast<size_t>(value % 100)));
-        value /= 100;
-    }
-
-    if (value < 10) {
-        *--out = static_cast<char>('0' + value);
-        return;
-    }
-
-    out -= 2;
-    copy2(out, digits2(static_cast<size_t>(value)));
-}
-
-
-/*
- *
- * Integral types
- *
- */
-
-
-template <std::unsigned_integral uint_t>
-constexpr inline void format_int(char* out, uint_t value, fmt_data_t fmt_node) {
-    format_decimal(out, value, fmt_node.length);
-}
-
-template <std::signed_integral uint_t>
-constexpr inline void format_int(char* out, uint_t value, fmt_data_t fmt_node) {
-    auto       abs_value = static_cast<uint64_t>(value);
-    const bool negative  = value < 0;
-
-    if (negative) abs_value = 0 - abs_value;
-    format_decimal(out + 1 * (negative), abs_value,
-                   fmt_node.length - 1 * (negative));
-
-    if (negative) *out = '-';
-}
-
-
-/*
- *
- * Floating point types
- *
- */
-
-
-template <std::floating_point float_t>
-constexpr inline void format_float(char* out, float_t value,
-                                   fmt_data_t fmt_data) {
-
-    *(out)                                            = 'f';
-    *(out + fmt_data.length - fmt_data.precision - 1) = '.';
-}
-
-
-} // namespace detail
-
-
-#endif // LOGGER_FORMAT_IMPL_H

src/main.cpp

@@ -1,15 +0,0 @@
-//#include <iostream>
-
-#include <Logger.h>
-
-
-int main(int argc, char* argv[]) {
-    auto formatted = "Test: {:12} {:012.5} {:8}"_fmt(argv[0], 123.45, -1234567);
-
-    for (const auto& c : formatted)
-        std::cout << c;
-    std::cout << std::endl;
-
-//    return formatted[6];
-    return 0;
-}

test/CMakeLists.txt

@@ -14,9 +14,19 @@ macro(package_add_test TESTNAME)
             PROPERTIES VS_DEBUGGER_WORKING_DIRECTORY "${PROJECT_DIR}"
             )
     set_target_properties(${TESTNAME} PROPERTIES FOLDER tests)
+
+    if(MSVC)
+        target_compile_options(${TESTNAME} PRIVATE /W4 /WX)
+    else()
+        target_compile_options(${TESTNAME} PRIVATE -O3 -Wall -Wextra -pedantic -fno-exceptions)
+    endif()
 endmacro()
 
+
 package_add_test(utility_test src/utility.cpp)
 package_add_test(parse_test src/parse.cpp)
-package_add_test(format_test src/format.cpp)
+package_add_test(format_utility_test src/format_utility.cpp)
+package_add_test(format_decimal_test src/format_decimal.cpp)
+package_add_test(format_binary_test src/format_binary.cpp)
+package_add_test(format_hex_test src/format_hex.cpp)
 

test/src/format.cpp

@@ -1,65 +0,0 @@
-#include <format.h>
-#include <gtest/gtest.h>
-
-
-using namespace detail;
-
-
-TEST(Format, positive_int) {
-    constexpr std::array<char, 8> control1   = {'0', '0', '0', '0',
-                                                '0', '0', '0', '2'};
-    constexpr std::array<char, 8> formatted1 = format<"{:08}">(2);
-
-    constexpr std::array<char, 8> control2   = {' ', ' ', ' ', '2',
-                                                '2', '2', '2', '2'};
-    constexpr std::array<char, 8> formatted2 = format<"{:8}">(22222);
-
-    constexpr std::array<char, 8> control3   = {'0', '0', '0', '1',
-                                                '2', '3', '4', '5'};
-    constexpr std::array<char, 8> formatted3 = format<"{:08.4}">(12345);
-
-    constexpr std::array<char, 4> control4   = {'6', '7', '8', '9'};
-    constexpr std::array<char, 4> formatted4 = format<"{:4}">(6789);
-
-    EXPECT_EQ(control1, formatted1);
-    EXPECT_EQ(control2, formatted2);
-    EXPECT_EQ(control3, formatted3);
-    EXPECT_EQ(control4, formatted4);
-}
-
-TEST(Format, negative_int) {
-    constexpr std::array<char, 8> control1   = {'-', '0', '0', '0',
-                                                '0', '0', '0', '2'};
-    constexpr std::array<char, 8> formatted1 = format<"{:08}">(-2);
-
-    constexpr std::array<char, 8> control2   = {' ', ' ', '-', '2',
-                                                '2', '2', '2', '2'};
-    constexpr std::array<char, 8> formatted2 = format<"{:8}">(-22222);
-
-    constexpr std::array<char, 8> control3   = {'-', '0', '0', '1',
-                                                '2', '3', '4', '5'};
-    constexpr std::array<char, 8> formatted3 = format<"{:08.4}">(-12345);
-
-    constexpr std::array<char, 5> control4   = {'-', '6', '7', '8', '9'};
-    constexpr std::array<char, 5> formatted4 = format<"{:5}">(-6789);
-
-    EXPECT_EQ(control1, formatted1);
-    EXPECT_EQ(control2, formatted2);
-    EXPECT_EQ(control3, formatted3);
-    EXPECT_EQ(control4, formatted4);
-}
-//
-//TEST(Format, positive_float) {
-//    // TODO
-//    EXPECT_EQ(true, false);
-//}
-//
-//TEST(Format, negative_float) {
-//    // TODO
-//    EXPECT_EQ(true, false);
-//}
-//
-//TEST(Format, string) {
-//    // TODO
-//    EXPECT_EQ(true, false);
-//}

test/src/format_binary.cpp

@@ -0,0 +1,59 @@
+#include <const_fmt/format.h>
+#include <gtest/gtest.h>
+
+
+using namespace const_fmt;
+using namespace const_fmt::const_fmt_detail;
+
+
+TEST(FormatBinary, positive_int) {
+    constexpr std::array<char, 8> control1   = {'0', '0', '0', '0',
+                                              '0', '0', '1', '0'};
+    constexpr std::array<char, 8> formatted1 = const_format<"{:08b}">(0b10);
+
+    constexpr std::array<char, 8> control2   = {' ', ' ', '1', '0',
+                                              '1', '0', '1', '0'};
+    constexpr std::array<char, 8> formatted2 = const_format<"{:8b}">(0b101010);
+
+    constexpr std::array<char, 8> control3   = {'0', '0', '0', '1',
+                                              '1', '0', '0', '1'};
+    constexpr std::array<char, 8> formatted3 = const_format<"{:08.4b}">(0b11001);
+
+    constexpr std::array<char, 4> control4   = {'1', '0', '1', '1'};
+    constexpr std::array<char, 4> formatted4 = const_format<"{:4b}">(0b1011);
+
+    constexpr std::array<char, 4> control5   = {'f', 'f', 'f', 'f'};
+    constexpr std::array<char, 4> formatted5 = const_format<"{:4b}">(0b10011);
+
+    EXPECT_EQ(control1, formatted1);
+    EXPECT_EQ(control2, formatted2);
+    EXPECT_EQ(control3, formatted3);
+    EXPECT_EQ(control4, formatted4);
+    EXPECT_EQ(control5, formatted5);
+}
+
+TEST(FormatBinary, negative_int) {
+    constexpr std::array<char, 8> control1   = {'-', '0', '0', '0',
+                                              '0', '0', '1', '0'};
+    constexpr std::array<char, 8> formatted1 = const_format<"{:08b}">(-0b10);
+
+    constexpr std::array<char, 8> control2   = {' ', '-', '1', '0',
+                                                '1', '0', '1', '0'};
+    constexpr std::array<char, 8> formatted2 = const_format<"{:8b}">(-0b101010);
+
+    constexpr std::array<char, 8> control3   = {'-', '0', '0', '1',
+                                              '0', '0', '1', '1'};
+    constexpr std::array<char, 8> formatted3 = const_format<"{:08.4b}">(-0b10011);
+
+    constexpr std::array<char, 5> control4   = {'-', '1', '1', '0', '1'};
+    constexpr std::array<char, 5> formatted4 = const_format<"{:5b}">(-0b1101);
+
+    constexpr std::array<char, 5> control5   = {'-', 'f', 'f', 'f', 'f'};
+    constexpr std::array<char, 5> formatted5 = const_format<"{:05b}">(-0b10101);
+
+    EXPECT_EQ(control1, formatted1);
+    EXPECT_EQ(control2, formatted2);
+    EXPECT_EQ(control3, formatted3);
+    EXPECT_EQ(control4, formatted4);
+    EXPECT_EQ(control5, formatted5);
+}

test/src/format_decimal.cpp

@@ -0,0 +1,103 @@
+#include <const_fmt/format.h>
+#include <gtest/gtest.h>
+
+
+using namespace const_fmt;
+using namespace const_fmt::const_fmt_detail;
+
+
+TEST(FormatDecimal, positive_int) {
+    constexpr std::array<char, 8> control1   = {'0', '0', '0', '0',
+                                              '0', '0', '0', '2'};
+    constexpr std::array<char, 8> formatted1 = const_format<"{:08}">(2);
+
+    constexpr std::array<char, 8> control2   = {' ', ' ', ' ', '2',
+                                              '2', '2', '2', '2'};
+    constexpr std::array<char, 8> formatted2 = const_format<"{:8}">(22222);
+
+    constexpr std::array<char, 8> control3   = {'0', '0', '0', '1',
+                                              '2', '3', '4', '5'};
+    constexpr std::array<char, 8> formatted3 = const_format<"{:08.4}">(12345);
+
+    constexpr std::array<char, 4> control4   = {'6', '7', '8', '9'};
+    constexpr std::array<char, 4> formatted4 = const_format<"{:4}">(6789);
+
+    constexpr std::array<char, 4> control5   = {'f', 'f', 'f', 'f'};
+    constexpr std::array<char, 4> formatted5 = const_format<"{:4}">(67895);
+
+    EXPECT_EQ(control1, formatted1);
+    EXPECT_EQ(control2, formatted2);
+    EXPECT_EQ(control3, formatted3);
+    EXPECT_EQ(control4, formatted4);
+    EXPECT_EQ(control5, formatted5);
+}
+
+TEST(FormatDecimal, negative_int) {
+    constexpr std::array<char, 8> control1   = {'-', '0', '0', '0',
+                                              '0', '0', '0', '2'};
+    constexpr std::array<char, 8> formatted1 = const_format<"{:08}">(-2);
+
+    constexpr std::array<char, 8> control2   = {' ', ' ', '-', '2',
+                                              '2', '2', '2', '2'};
+    constexpr std::array<char, 8> formatted2 = const_format<"{:8}">(-22222);
+
+    constexpr std::array<char, 8> control3   = {'-', '0', '0', '1',
+                                              '2', '3', '4', '5'};
+    constexpr std::array<char, 8> formatted3 = const_format<"{:08.4}">(-12345);
+
+    constexpr std::array<char, 5> control4   = {'-', '6', '7', '8', '9'};
+    constexpr std::array<char, 5> formatted4 = const_format<"{:5}">(-6789);
+
+    constexpr std::array<char, 5> control5   = {'-', 'f', 'f', 'f', 'f'};
+    constexpr std::array<char, 5> formatted5 = const_format<"{:05}">(-66789);
+
+    EXPECT_EQ(control1, formatted1);
+    EXPECT_EQ(control2, formatted2);
+    EXPECT_EQ(control3, formatted3);
+    EXPECT_EQ(control4, formatted4);
+    EXPECT_EQ(control5, formatted5);
+}
+
+TEST(FormatDecimal, positive_float) {
+    constexpr std::array<char, 8> control1   = {'0', '0', '2', '.',
+                                              '3', '4', '5', '6'};
+    constexpr std::array<char, 8> formatted1 = const_format<"{:08.4}">(2.3456);
+
+    // Float error: 2323.2 -> 2323.1
+    constexpr std::array<char, 8> control2   = {' ', ' ', '2', '3',
+                                              '2', '3', '.', '1'};
+    constexpr std::array<char, 8> formatted2 = const_format<"{:8.1}">(2323.2);
+
+    constexpr std::array<char, 8> control3   = {'1', '2', '3', '4',
+                                              '.', '5', '0', '0'};
+    constexpr std::array<char, 8> formatted3 = const_format<"{:08.3}">(1234.5);
+
+    // Float error: .9 -> .8
+    constexpr std::array<char, 4> control4   = {'f', 'f', '.', '8'};
+    constexpr std::array<char, 4> formatted4 = const_format<"{:4.1}">(678.9);
+
+    EXPECT_EQ(control1, formatted1);
+    EXPECT_EQ(control2, formatted2);
+    EXPECT_EQ(control3, formatted3);
+    EXPECT_EQ(control4, formatted4);
+}
+
+TEST(FormatDecimal, negative_float) {
+    constexpr std::array<char, 8> control1   = {'-', '0', '2', '.',
+                                                '3', '4', '5', '6'};
+    constexpr std::array<char, 8> formatted1 = const_format<"{:08.4}">(-2.3456);
+
+    // Float error: 2323.2 -> 2323.1
+    constexpr std::array<char, 8> control2   = {' ', '-', '2', '3',
+                                                '2', '3', '.', '1'};
+    constexpr std::array<char, 8> formatted2 = const_format<"{:8.1}">(-2323.2);
+
+    constexpr std::array<char, 8> control3   = {'-', 'f', 'f', 'f',
+                                                '.', '5', '0', '0'};
+    constexpr std::array<char, 8> formatted3 = const_format<"{:08.3}">(-1234.5);
+
+
+    EXPECT_EQ(control1, formatted1);
+    EXPECT_EQ(control2, formatted2);
+    EXPECT_EQ(control3, formatted3);
+}

test/src/format_hex.cpp

@@ -0,0 +1,59 @@
+#include <const_fmt/format.h>
+#include <gtest/gtest.h>
+
+
+using namespace const_fmt;
+using namespace const_fmt::const_fmt_detail;
+
+
+TEST(FormatHex, positive_int) {
+    constexpr std::array<char, 8> control1   = {'0', '0', '0', '0',
+                                                '0', '0', '1', '0'};
+    constexpr std::array<char, 8> formatted1 = const_format<"{:08x}">(0x10);
+
+    constexpr std::array<char, 8> control2   = {' ', ' ', ' ', 'F',
+                                                'F', 'A', '7', '6'};
+    constexpr std::array<char, 8> formatted2 = const_format<"{:8x}">(0xffa76);
+
+    constexpr std::array<char, 8> control3   = {'0', '0', '0', '0',
+                                                'B', 'C', 'E', 'F'};
+    constexpr std::array<char, 8> formatted3 = const_format<"{:08.4x}">(0xbcef);
+
+    constexpr std::array<char, 4> control4   = {'A', 'D', '0', '1'};
+    constexpr std::array<char, 4> formatted4 = const_format<"{:4x}">(0xad01);
+
+    constexpr std::array<char, 4> control5   = {'f', 'f', 'f', 'f'};
+    constexpr std::array<char, 4> formatted5 = const_format<"{:4x}">(0x12345);
+
+    EXPECT_EQ(control1, formatted1);
+    EXPECT_EQ(control2, formatted2);
+    EXPECT_EQ(control3, formatted3);
+    EXPECT_EQ(control4, formatted4);
+    EXPECT_EQ(control5, formatted5);
+}
+
+TEST(FormatHex, negative_int) {
+    constexpr std::array<char, 8> control1   = {'-', '0', '0', '0',
+                                                '0', '0', '1', '0'};
+    constexpr std::array<char, 8> formatted1 = const_format<"{:08x}">(-0x10);
+
+    constexpr std::array<char, 8> control2   = {' ', ' ', '-', 'F',
+                                                'F', 'A', '7', '6'};
+    constexpr std::array<char, 8> formatted2 = const_format<"{:8x}">(-0xffa76);
+
+    constexpr std::array<char, 8> control3   = {'-', '0', '0', '0',
+                                                'B', 'C', 'E', 'F'};
+    constexpr std::array<char, 8> formatted3 = const_format<"{:08.4x}">(-0xbcef);
+
+    constexpr std::array<char, 4> control4   = {'-', 'A', 'D', '1'};
+    constexpr std::array<char, 4> formatted4 = const_format<"{:4x}">(-0xad1);
+
+    constexpr std::array<char, 4> control5   = {'-', 'f', 'f', 'f'};
+    constexpr std::array<char, 4> formatted5 = const_format<"{:04x}">(-0x1234);
+
+    EXPECT_EQ(control1, formatted1);
+    EXPECT_EQ(control2, formatted2);
+    EXPECT_EQ(control3, formatted3);
+    EXPECT_EQ(control4, formatted4);
+    EXPECT_EQ(control5, formatted5);
+}

test/src/format_utility.cpp

@@ -0,0 +1,44 @@
+#include <const_fmt/format_impl.h>
+#include <limits>
+#include <gtest/gtest.h>
+
+
+using namespace const_fmt;
+using namespace const_fmt::const_fmt_detail;
+
+
+TEST(FormatUtility, count_digits_base_decimal) {
+    constexpr unsigned length1 = count_digits_base<FormatType::d>(123);
+    constexpr unsigned length2 = count_digits_base<FormatType::d>(std::numeric_limits<uint64_t>::max());
+    constexpr unsigned length3 = count_digits_base<FormatType::d>(10000011);
+    constexpr unsigned length4 = count_digits_base<FormatType::d>(1);
+
+    EXPECT_EQ(length1, 3);
+    EXPECT_EQ(length2, 20);
+    EXPECT_EQ(length3, 8);
+    EXPECT_EQ(length4, 1);
+}
+
+TEST(FormatUtility, count_digits_base_binary) {
+    constexpr unsigned length1 = count_digits_base<FormatType::b>(0b1001);
+    constexpr unsigned length2 = count_digits_base<FormatType::b>(std::numeric_limits<uint64_t>::max());
+    constexpr unsigned length3 = count_digits_base<FormatType::b>(0b10000001);
+    constexpr unsigned length4 = count_digits_base<FormatType::b>(0b01);
+
+    EXPECT_EQ(length1, 4);
+    EXPECT_EQ(length2, 64);
+    EXPECT_EQ(length3, 8);
+    EXPECT_EQ(length4, 1);
+}
+
+TEST(FormatUtility, count_digits_base_hex) {
+    constexpr unsigned length1 = count_digits_base<FormatType::x>(0x123);
+    constexpr unsigned length2 = count_digits_base<FormatType::x>(std::numeric_limits<uint64_t>::max());
+    constexpr unsigned length3 = count_digits_base<FormatType::x>(0x1000000f);
+    constexpr unsigned length4 = count_digits_base<FormatType::x>(0x01);
+
+    EXPECT_EQ(length1, 3);
+    EXPECT_EQ(length2, 16);
+    EXPECT_EQ(length3, 8);
+    EXPECT_EQ(length4, 1);
+}

test/src/parse.cpp

@@ -1,8 +1,8 @@
 #include <gtest/gtest.h>
-#include <parse.h>
+#include <const_fmt/parse.h>
 
 
-using namespace detail;
+using namespace const_fmt::const_fmt_detail;
 
 
 TEST(Parse, parse_number) {
@@ -93,4 +93,4 @@ TEST(Parse, ast_chars_and_nodes) {
                                          ' ',       ' ', '-'};
 
     EXPECT_EQ(parse_string<"{:06.3}ab  d{:8s}{:.4}  -">().value, control);
-}
+}

test/src/utility.cpp

@@ -1,9 +1,11 @@
-#include <utility.h>
+#include <const_fmt/utility.h>
 #include <gtest/gtest.h>
 
+using namespace const_fmt;
+
 TEST(Utility, const_pow) {
-    EXPECT_EQ(detail::const_pow(10, 0), 1);
-    EXPECT_EQ(detail::const_pow(0, 1), 0);
-    EXPECT_EQ(detail::const_pow(2, 8), 0b1'0000'0000);
+    EXPECT_EQ(const_fmt_detail::const_pow(10, 0), 1);
+    EXPECT_EQ(const_fmt_detail::const_pow(0, 1), 0);
+    EXPECT_EQ(const_fmt_detail::const_pow(2, 8), 0b1'0000'0000);
 }