Added missing return in format_decimal(); Added first support for negative numbers

inc/format.h

@@ -40,21 +40,16 @@ constexpr inline void check_fmt_params() {
  *
  */
 
-// TODO: Error handling
 template <fmt_data_t fmt_data, std::integral arg_t>
 constexpr inline void format_arg(char* dest, arg_t arg) {
-    constexpr auto error_array = get_init_array<fmt_data.length>('f');
-
     detail::format_int(dest, arg, fmt_data);
 };
-// TODO: Error handling
+
 template <fmt_data_t fmt_data, std::floating_point arg_t>
 constexpr inline void format_arg(char* dest, arg_t arg) {
-    *(dest) = 'f';
-    *(dest + fmt_data.length - fmt_data.precision - 1) = '.';
-
     //detail::format_float(dest, arg, fmt_data);
 };
+
 // TODO: Error handling
 template<fmt_data_t fmt_data>
 constexpr inline void format_arg(char* dest, const char* arg) {
@@ -87,7 +82,7 @@ constexpr inline void format_args(char* dest, first_arg_t first_arg, args_t... a
 
 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>()>('0');
+    auto result = get_init_array<get_ast_output_len<ast>()>('f');
 
     int i = 0;
 

inc/format_impl.h

@@ -31,42 +31,6 @@ namespace detail {
         (factor)*1000000, (factor)*10000000, (factor)*100000000,               \
         (factor)*1000000000
 
-
-// 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) {
-    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);
-
-    out -= 2;
-    copy2(out, digits2(static_cast<size_t>(value)));
-}
-
 template <typename T>
 constexpr int count_digits_fallback(T n) {
     int count = 1;
@@ -102,6 +66,47 @@ constexpr inline auto count_digits(uint64_t n) -> int {
 }
 
 
+// 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
@@ -116,8 +121,14 @@ constexpr inline void format_int(char* out, uint_t value, fmt_data_t fmt_node) {
 
 template <std::signed_integral uint_t>
 constexpr inline void format_int(char* out, uint_t value, fmt_data_t fmt_node) {
-    if (value < 0) value = -value;
+    auto       abs_value = static_cast<uint64_t>(value);
-    format_decimal(out, value, fmt_node.length);
+    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 = '-';
 }
 
 
@@ -130,8 +141,10 @@ constexpr inline void format_int(char* out, uint_t value, fmt_data_t fmt_node) {
 
 template <std::floating_point float_t>
 constexpr inline void format_float(char* out, float_t value,
-                                   fmt_data_t fmt_node) {
+                                   fmt_data_t fmt_data) {
-    // TODO
+
+    *(out)                                            = 'f';
+    *(out + fmt_data.length - fmt_data.precision - 1) = '.';
 }
 
 

src/main.cpp

@@ -4,11 +4,12 @@
 
 
 int main(int argc, char* argv[]) {
-    auto formatted = "Test: {:12} {:012.5} {:8}"_fmt(argv[0], argc, -1234);
+    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 formatted[6];
+    return 0;
 }