Add integral type handler

include/fmt/format.h

@@ -1707,6 +1707,29 @@ typedef basic_format_specs<char> format_specs;
 
 namespace internal {
 
+template <typename Handler>
+void handle_integral_type_spec(char c, Handler &&handler) {
+  switch (c) {
+  case 0: case 'd':
+    handler.on_dec();
+    break;
+  case 'x': case 'X':
+    handler.on_hex();
+    break;
+  case 'b': case 'B':
+    handler.on_bin();
+    break;
+  case 'o':
+    handler.on_oct();
+    break;
+  case 'n':
+    handler.on_num();
+    break;
+  default:
+    handler.on_error();
+  }
+}
+
 template <typename Context>
 class arg_map {
  private:
@@ -2485,10 +2508,16 @@ typename basic_writer<Char>::pointer_type
 template <typename Char>
 template <typename T, typename Spec>
 void basic_writer<Char>::write_int(T value, const Spec& spec) {
+  struct spec_handler {
+    basic_writer<Char> &writer;
+    const Spec& spec;
     unsigned prefix_size = 0;
     typedef typename internal::int_traits<T>::main_type UnsignedType;
-  UnsignedType abs_value = static_cast<UnsignedType>(value);
+    UnsignedType abs_value;
     char prefix[4] = "";
+
+    spec_handler(basic_writer<Char> &w, T value, const Spec& s)
+      : writer(w), abs_value(static_cast<UnsignedType>(value)), spec(s) {
       if (internal::is_negative(value)) {
         prefix[0] = '-';
         ++prefix_size;
@@ -2497,15 +2526,16 @@ void basic_writer<Char>::write_int(T value, const Spec& spec) {
         prefix[0] = spec.flag(PLUS_FLAG) ? '+' : ' ';
         ++prefix_size;
       }
-  switch (spec.type()) {
-  case 0: case 'd': {
+    }
+
+    void on_dec() {
       unsigned num_digits = internal::count_digits(abs_value);
       pointer_type p =
-        prepare_int_buffer(num_digits, spec, prefix, prefix_size) + 1;
+          writer.prepare_int_buffer(num_digits, spec, prefix, prefix_size) + 1;
       internal::format_decimal(get(p), abs_value, 0);
-    break;
     }
-  case 'x': case 'X': {
+
+    void on_hex() {
       UnsignedType n = abs_value;
       if (spec.flag(HASH_FLAG)) {
         prefix[prefix_size++] = '0';
@@ -2515,17 +2545,17 @@ void basic_writer<Char>::write_int(T value, const Spec& spec) {
       do {
         ++num_digits;
       } while ((n >>= 4) != 0);
-    Char *p = get(prepare_int_buffer(
-      num_digits, spec, prefix, prefix_size));
+      Char *p =
+          get(writer.prepare_int_buffer(num_digits, spec, prefix, prefix_size));
       n = abs_value;
       const char *digits = spec.type() == 'x' ?
           "0123456789abcdef" : "0123456789ABCDEF";
       do {
         *p-- = digits[n & 0xf];
       } while ((n >>= 4) != 0);
-    break;
     }
-  case 'b': case 'B': {
+
+    void on_bin() {
       UnsignedType n = abs_value;
       if (spec.flag(HASH_FLAG)) {
         prefix[prefix_size++] = '0';
@@ -2535,14 +2565,15 @@ void basic_writer<Char>::write_int(T value, const Spec& spec) {
       do {
         ++num_digits;
       } while ((n >>= 1) != 0);
-    Char *p = get(prepare_int_buffer(num_digits, spec, prefix, prefix_size));
+      Char *p =
+          get(writer.prepare_int_buffer(num_digits, spec, prefix, prefix_size));
       n = abs_value;
       do {
         *p-- = static_cast<Char>('0' + (n & 1));
       } while ((n >>= 1) != 0);
-    break;
     }
-  case 'o': {
+
+    void on_oct() {
       UnsignedType n = abs_value;
       if (spec.flag(HASH_FLAG))
         prefix[prefix_size++] = '0';
@@ -2550,31 +2581,35 @@ void basic_writer<Char>::write_int(T value, const Spec& spec) {
       do {
         ++num_digits;
       } while ((n >>= 3) != 0);
-    Char *p = get(prepare_int_buffer(num_digits, spec, prefix, prefix_size));
+      Char *p =
+          get(writer.prepare_int_buffer(num_digits, spec, prefix, prefix_size));
       n = abs_value;
       do {
         *p-- = static_cast<Char>('0' + (n & 7));
       } while ((n >>= 3) != 0);
-    break;
     }
-  case 'n': {
+
+    void on_num() {
       unsigned num_digits = internal::count_digits(abs_value);
-    std::locale loc = buffer_.locale();
+      std::locale loc = writer.buffer_.locale();
       Char thousands_sep =
           std::use_facet<std::numpunct<Char>>(loc).thousands_sep();
       fmt::basic_string_view<Char> sep(&thousands_sep, 1);
       unsigned size = static_cast<unsigned>(
             num_digits + sep.size() * ((num_digits - 1) / 3));
-    pointer_type p = prepare_int_buffer(size, spec, prefix, prefix_size) + 1;
+      pointer_type p =
+          writer.prepare_int_buffer(size, spec, prefix, prefix_size) + 1;
       internal::format_decimal(get(p), abs_value, 0,
                                internal::add_thousands_sep<Char>(sep));
-    break;
     }
-  default:
+
+    void on_error() {
       internal::report_unknown_type(
         spec.type(), spec.flag(CHAR_FLAG) ? "char" : "integer");
-    break;
     }
+  };
+  internal::handle_integral_type_spec(
+        spec.type(), spec_handler(*this, value, spec));
 }
 
 template <typename Char>