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Check format string at compile time in print

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This commit is contained in:
Victor Zverovich 2018-03-07 05:41:45 -08:00
parent 585512fc7c
commit ae3cc844e7
1 changed files with 23 additions and 7 deletions
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30
include/fmt/format.h
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@ -1468,6 +1468,10 @@ class arg_formatter_base {
struct format_string {};
template <typename S>
struct is_format_string:
std::integral_constant<bool, std::is_base_of<format_string, S>::value> {};
template <typename Char>
FMT_CONSTEXPR bool is_name_start(Char c) {
return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || '_' == c;
@ -2093,6 +2097,14 @@ FMT_CONSTEXPR bool check_format_string(
return true;
}
template <typename... Args, typename String>
void check_format_string(String format_str) {
FMT_CONSTEXPR_DECL bool invalid_format =
internal::check_format_string<char, internal::error_handler, Args...>(
string_view(format_str.data(), format_str.size()));
(void)invalid_format;
}
// Specifies whether to format T using the standard formatter.
// It is not possible to use get_type in formatter specialization directly
// because of a bug in MSVC.
@ -3399,13 +3411,17 @@ inline std::wstring vformat(wstring_view format_str, wformat_args args) {
template <typename String, typename... Args>
inline typename std::enable_if<
std::is_base_of<internal::format_string, String>::value, std::string>::type
internal::is_format_string<String>::value, std::string>::type
format(String format_str, const Args & ... args) {
FMT_CONSTEXPR_DECL bool invalid_format =
internal::check_format_string<char, internal::error_handler, Args...>(
string_view(format_str.value(), format_str.size()));
(void)invalid_format;
return vformat(format_str.value(), make_args(args...));
internal::check_format_string<Args...>(format_str);
return vformat(format_str.data(), make_args(args...));
}
template <typename String, typename... Args>
inline typename std::enable_if<internal::is_format_string<String>::value>::type
print(String format_str, const Args & ... args) {
internal::check_format_string<Args...>(format_str);
return vprint(format_str.data(), make_args(args...));
}
// Counts the number of characters in the output of format(format_str, args...).
@ -3505,7 +3521,7 @@ operator"" _a(const wchar_t *s, std::size_t) { return {s}; }
#define FMT_STRING(s) [] { \
struct S : fmt::internal::format_string { \
static FMT_CONSTEXPR auto value() { return s; } \
static FMT_CONSTEXPR auto data() { return s; } \
static FMT_CONSTEXPR size_t size() { return sizeof(s); } \
}; \
return S{}; \