Forbid copying from a temporary (Basic)Formatter object.

This commit is contained in:
Victor Zverovich 2013-12-04 22:22:25 -08:00
parent e8a2bdf2d1
commit 383a8423ef
2 changed files with 25 additions and 32 deletions

View File

@ -774,7 +774,8 @@ BasicWriter<Char> &BasicWriter<Char>::operator<<(
template <typename Char>
BasicFormatter<Char> BasicWriter<Char>::Format(StringRef format) {
return BasicFormatter<Char>(*this, format.c_str());
BasicFormatter<Char> f(*this, format.c_str());
return f;
}
typedef BasicWriter<char> Writer;
@ -936,8 +937,12 @@ class BasicFormatter {
friend class internal::FormatterProxy<Char>;
// Forbid copying other than from a temporary. Do not implement.
BasicFormatter(BasicFormatter &);
// Forbid copying from a temporary as in the following example:
// fmt::Formatter<> f = Format("test"); // not allowed
// This is done because BasicFormatter objects should normally exist
// only as temporaries returned by one of the formatting functions.
// Do not implement.
BasicFormatter(const BasicFormatter &);
BasicFormatter& operator=(const BasicFormatter &);
void Add(const Arg &arg) {
@ -988,13 +993,8 @@ class BasicFormatter {
CompleteFormatting();
}
// Constructs a formatter from a proxy object.
BasicFormatter(const Proxy &p) : writer_(p.writer), format_(p.format) {}
operator Proxy() {
const Char *format = format_;
format_ = 0;
return Proxy(writer_, format);
BasicFormatter(BasicFormatter &f) : writer_(f.writer_), format_(f.format_) {
f.format_ = 0;
}
// Feeds an argument to a formatter.
@ -1089,7 +1089,7 @@ class NoAction {
// Formats an error message and prints it to stdout.
fmt::Formatter<PrintError> ReportError(const char *format) {
return fmt::Formatter<PrintError>(format);
return Move(fmt::Formatter<PrintError>(format));
}
ReportError("File not found: {}") << path;
@ -1102,16 +1102,9 @@ class Formatter : private Action, public BasicFormatter<Char> {
bool inactive_;
// Forbid copying other than from a temporary. Do not implement.
Formatter(Formatter &);
Formatter(const Formatter &);
Formatter& operator=(const Formatter &);
struct Proxy {
const Char *format;
Action action;
Proxy(const Char *fmt, Action a) : format(fmt), action(a) {}
};
public:
/**
\rst
@ -1127,10 +1120,10 @@ class Formatter : private Action, public BasicFormatter<Char> {
inactive_(false) {
}
// Constructs a formatter from a proxy object.
Formatter(const Proxy &p)
: Action(p.action), BasicFormatter<Char>(writer_, p.format),
Formatter(Formatter &f)
: Action(f), BasicFormatter<Char>(writer_, f.TakeFormatString()),
inactive_(false) {
f.inactive_ = true;
}
/**
@ -1142,14 +1135,14 @@ class Formatter : private Action, public BasicFormatter<Char> {
(*this)(writer_);
}
}
// Converts the formatter into a proxy object.
operator Proxy() {
inactive_ = true;
return Proxy(this->TakeFormatString(), *this);
}
};
// Removes a const qualifier from a formatter object making it moveable.
template <typename Action, typename Char>
Formatter<Action, Char> &Move(const Formatter<Action, Char> &f) {
return const_cast<Formatter<Action, Char> &>(f);
}
/**
Fast integer formatter.
*/
@ -1223,11 +1216,11 @@ class FormatInt {
\endrst
*/
inline Formatter<> Format(StringRef format) {
return Formatter<>(format);
return Move(Formatter<>(format));
}
inline Formatter<NoAction, wchar_t> Format(WStringRef format) {
return Formatter<NoAction, wchar_t>(format);
return Move(Formatter<NoAction, wchar_t>(format));
}
/** A formatting action that writes formatted output to stdout. */
@ -1243,7 +1236,7 @@ class Write {
// Example:
// Print("Elapsed time: {0:.2f} seconds") << 1.23;
inline Formatter<Write> Print(StringRef format) {
return Formatter<Write>(format);
return Move(Formatter<Write>(format));
}
}

View File

@ -1327,7 +1327,7 @@ struct PrintError {
};
fmt::Formatter<PrintError> ReportError(const char *format) {
return fmt::Formatter<PrintError>(format);
return Move(fmt::Formatter<PrintError>(format));
}
TEST(FormatterTest, Examples) {