Implement empty format specs

fmtlib · Jan 1, 2024 · fe108bc · fe108bc
1 parent c068c7c
commit fe108bc
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Showing 2 changed files with 67 additions and 56 deletions.
diff --git a/test/scan-test.cc b/test/scan-test.cc
@@ -29,6 +29,8 @@ TEST(scan_test, read_int) {
   EXPECT_EQ(n, 42);
   fmt::scan("-42", "{}", n);
   EXPECT_EQ(n, -42);
+  fmt::scan("42", "{:}", n);
+  EXPECT_EQ(n, 42);
   EXPECT_THROW_MSG(fmt::scan(std::to_string(INT_MAX + 1u), "{}", n),
                    fmt::format_error, "number is too big");
 }

diff --git a/test/scan.h b/test/scan.h
@@ -147,6 +147,9 @@ class scan_buffer {
   }
 };
 
+using scan_iterator = scan_buffer::iterator;
+using scan_sentinel = scan_buffer::sentinel;
+
 class string_scan_buffer : public scan_buffer {
  private:
   void consume() override {}
@@ -456,77 +459,78 @@ const char* parse_scan_specs(const char* begin, const char* end,
   return begin;
 }
 
+template <typename T, FMT_ENABLE_IF(std::is_unsigned<T>::value)>
+auto read(scan_iterator it, T& value) -> scan_iterator {
+  if (it == scan_sentinel()) return it;
+  char c = *it;
+  if (c < '0' || c > '9') throw_format_error("invalid input");
+
+  int num_digits = 0;
+  T n = 0, prev = 0;
+  char prev_digit = c;
+  do {
+    prev = n;
+    n = n * 10 + static_cast<unsigned>(c - '0');
+    prev_digit = c;
+    c = *++it;
+    ++num_digits;
+    if (c < '0' || c > '9') break;
+  } while (it != scan_sentinel());
+
+  // Check overflow.
+  if (num_digits <= std::numeric_limits<int>::digits10) {
+    value = n;
+    return it;
+  }
+  unsigned max = to_unsigned((std::numeric_limits<int>::max)());
+  if (num_digits == std::numeric_limits<int>::digits10 + 1 &&
+      prev * 10ull + unsigned(prev_digit - '0') <= max) {
+    value = n;
+  } else {
+    throw_format_error("number is too big");
+  }
+  return it;
+}
+
+template <typename T, FMT_ENABLE_IF(std::is_signed<T>::value)>
+auto read(scan_iterator it, T& value) -> scan_iterator {
+  bool negative = it != scan_sentinel() && *it == '-';
+  if (negative) {
+    ++it;
+    if (it == scan_sentinel()) throw_format_error("invalid input");
+  }
+  using unsigned_type = typename std::make_unsigned<T>::type;
+  unsigned_type abs_value = 0;
+  it = read(it, abs_value);
+  auto n = static_cast<T>(abs_value);
+  value = negative ? -n : n;
+  return it;
+}
+
 struct default_arg_scanner {
   using iterator = scan_buffer::iterator;
   using sentinel = scan_buffer::sentinel;
 
   iterator begin;
 
-  template <typename T = unsigned>
-  auto read_uint(iterator it, T& value) -> iterator {
-    if (it == sentinel()) return it;
-    char c = *it;
-    if (c < '0' || c > '9') throw_format_error("invalid input");
-
-    int num_digits = 0;
-    T n = 0, prev = 0;
-    char prev_digit = c;
-    do {
-      prev = n;
-      n = n * 10 + static_cast<unsigned>(c - '0');
-      prev_digit = c;
-      c = *++it;
-      ++num_digits;
-      if (c < '0' || c > '9') break;
-    } while (it != sentinel());
-
-    // Check overflow.
-    if (num_digits <= std::numeric_limits<int>::digits10) {
-      value = n;
-      return it;
-    }
-    unsigned max = to_unsigned((std::numeric_limits<int>::max)());
-    if (num_digits == std::numeric_limits<int>::digits10 + 1 &&
-        prev * 10ull + unsigned(prev_digit - '0') <= max) {
-      value = n;
-    } else {
-      throw_format_error("number is too big");
-    }
-    return it;
-  }
-
-  template <typename T = int>
-  auto read_int(iterator it, T& value) -> iterator {
-    bool negative = it != sentinel() && *it == '-';
-    if (negative) {
-      ++it;
-      if (it == sentinel()) throw_format_error("invalid input");
-    }
-    using unsigned_type = typename std::make_unsigned<T>::type;
-    unsigned_type abs_value = 0;
-    it = read_uint<unsigned_type>(it, abs_value);
-    auto n = static_cast<T>(abs_value);
-    value = negative ? -n : n;
-    return it;
-  }
-
   auto operator()(int& value) -> iterator {
-    return read_int(begin, value);
+    return read(begin, value);
   }
   auto operator()(unsigned& value) -> iterator {
-    return read_uint(begin, value);
+    return read(begin, value);
   }
   auto operator()(long long& value) -> iterator {
-    return read_int<long long>(begin, value);
+    return read(begin, value);
   }
   auto operator()(unsigned long long& value) -> iterator {
-    return read_uint<unsigned long long>(begin, value);
+    return read(begin, value);
   }
   auto operator()(std::string& value) -> iterator {
     iterator it = begin;
     while (it != sentinel() && *it != ' ') value.push_back(*it++);
     return it;
   }
+
   auto operator()(fmt::string_view& value) -> iterator {
     auto range = to_contiguous(begin);
     // This could also be checked at compile time in scan.
@@ -537,6 +541,7 @@ struct default_arg_scanner {
     value = {range.begin, size};
     return advance(begin, size);
   }
+
   auto operator()(monostate) -> iterator {
     return begin;
   }
@@ -550,16 +555,20 @@ struct arg_scanner {
   const format_specs<>& specs;
 
   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
-  auto operator()(T&&) -> iterator {
-    // TODO: implement
-    return begin;
+  auto operator()(T& value) -> iterator {
+    // TODO: handle specs
+    return read(begin, value);
   }
 
   template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
-  auto operator()(T&&) -> iterator {
+  auto operator()(T&) -> iterator {
     // TODO: implement
     return begin;
   }
+
+  auto operator()(monostate) -> iterator {
+    return begin;
+  }
 };
 
 struct scan_handler : error_handler {