/*
- * Copyright 2017 Facebook, Inc.
+ * Copyright 2012-present Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
#define FOLLY_FORMAT_H_
#include <cstdio>
+#include <stdexcept>
#include <tuple>
#include <type_traits>
+#include <folly/CPortability.h>
#include <folly/Conv.h>
#include <folly/FormatArg.h>
#include <folly/Range.h>
#include <folly/Traits.h>
// Ignore shadowing warnings within this file, so includers can use -Wshadow.
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wshadow"
+FOLLY_PUSH_WARNING
+FOLLY_GCC_DISABLE_WARNING("-Wshadow")
namespace folly {
// meta-attribute to identify formatters in this sea of template weirdness
namespace detail {
class FormatterTag {};
-};
+} // namespace detail
/**
* Formatter class.
*
- * Note that this class is tricky, as it keeps *references* to its arguments
- * (and doesn't copy the passed-in format string). Thankfully, you can't use
- * this directly, you have to use format(...) below.
+ * Note that this class is tricky, as it keeps *references* to its lvalue
+ * arguments (while it takes ownership of the temporaries), and it doesn't
+ * copy the passed-in format string. Thankfully, you can't use this
+ * directly, you have to use format(...) below.
*/
-/* BaseFormatter class. Currently, the only behavior that can be
- * overridden is the actual formatting of positional parameters in
+/* BaseFormatter class.
+ * Overridable behaviours:
+ * You may override the actual formatting of positional parameters in
* `doFormatArg`. The Formatter class provides the default implementation.
+ *
+ * You may also override `doFormat` and `getSizeArg`. These override points were
+ * added to permit static analysis of format strings, when it is inconvenient
+ * or impossible to instantiate a BaseFormatter with the correct storage
*/
template <class Derived, bool containerMode, class... Args>
class BaseFormatter {
}
/**
- * metadata to identify generated children of BaseFormatter
+ * Metadata to identify generated children of BaseFormatter
*/
typedef detail::FormatterTag IsFormatter;
typedef BaseFormatter BaseType;
private:
- typedef std::tuple<FormatValue<typename std::decay<Args>::type>...>
- ValueTuple;
+ typedef std::tuple<Args...> ValueTuple;
static constexpr size_t valueCount = std::tuple_size<ValueTuple>::value;
+ Derived const& asDerived() const {
+ return *static_cast<const Derived*>(this);
+ }
+
template <size_t K, class Callback>
typename std::enable_if<K == valueCount>::type
doFormatFrom(size_t i, FormatArg& arg, Callback& /*cb*/) const {
typename std::enable_if<(K < valueCount)>::type
doFormatFrom(size_t i, FormatArg& arg, Callback& cb) const {
if (i == K) {
- static_cast<const Derived*>(this)->template doFormatArg<K>(arg, cb);
+ asDerived().template doFormatArg<K>(arg, cb);
} else {
doFormatFrom<K + 1>(i, arg, cb);
}
K<valueCount, int>::type getSizeArgFrom(size_t i, const FormatArg& arg)
const {
if (i == K) {
- return getValue(std::get<K>(values_), arg);
+ return getValue(getFormatValue<K>(), arg);
}
return getSizeArgFrom<K + 1>(i, arg);
}
// for the exclusive use of format() (below). This way, you can't create
// a Formatter object, but can handle references to it (for streaming,
// conversion to string, etc) -- which is good, as Formatter objects are
- // dangerous (they hold references, possibly to temporaries)
+ // dangerous (they may hold references).
BaseFormatter(BaseFormatter&&) = default;
BaseFormatter& operator=(BaseFormatter&&) = default;
+ template <size_t K>
+ using ArgType = typename std::tuple_element<K, ValueTuple>::type;
+
+ template <size_t K>
+ FormatValue<typename std::decay<ArgType<K>>::type> getFormatValue() const {
+ return FormatValue<typename std::decay<ArgType<K>>::type>(
+ std::get<K>(values_));
+ }
+
ValueTuple values_;
};
: BaseFormatter<
Formatter<containerMode, Args...>,
containerMode,
- Args...>(str, std::forward<Args>(args)...) {}
+ Args...>(str, std::forward<Args>(args)...) {
+ static_assert(
+ !containerMode || sizeof...(Args) == 1,
+ "Exactly one argument required in container mode");
+ }
template <size_t K, class Callback>
void doFormatArg(FormatArg& arg, Callback& cb) const {
- std::get<K>(this->values_).format(arg, cb);
+ this->template getFormatValue<K>().format(arg, cb);
}
friend class BaseFormatter<
return vformat(fmt, std::forward<Container>(container)).str();
}
+/**
+ * Exception class thrown when a format key is not found in the given
+ * associative container keyed by strings. We inherit std::out_of_range for
+ * compatibility with callers that expect exception to be thrown directly
+ * by std::map or std::unordered_map.
+ *
+ * Having the key be at the end of the message string, we can access it by
+ * simply adding its offset to what(). Not storing separate std::string key
+ * makes the exception type small and noexcept-copyable like std::out_of_range,
+ * and therefore able to fit in-situ in exception_wrapper.
+ */
+class FOLLY_EXPORT FormatKeyNotFoundException : public std::out_of_range {
+ public:
+ explicit FormatKeyNotFoundException(StringPiece key);
+
+ char const* key() const noexcept {
+ return what() + kMessagePrefix.size();
+ }
+
+ private:
+ static constexpr StringPiece const kMessagePrefix = "format key not found: ";
+};
+
+namespace detail {
+[[noreturn]] void throwFormatKeyNotFoundException(StringPiece key);
+} // namespace detail
+
/**
* Wrap a sequence or associative container so that out-of-range lookups
* return a default value rather than throwing an exception.
const Container& container;
const Value& defaultValue;
};
-} // namespace
+} // namespace detail
template <class Container, class Value>
detail::DefaultValueWrapper<Container, Value> defaulted(
typename std::enable_if<
std::is_same<typename T::IsFormatter, detail::FormatterTag>::value>::
type> : public std::true_type {};
-} // folly::detail
+} // namespace detail
// Deprecated API. formatChecked() et. al. now behave identically to their
// non-Checked counterparts.
#include <folly/Format-inl.h>
-#pragma GCC diagnostic pop
+FOLLY_POP_WARNING
projects / folly.git / blobdiff