/*
- * Copyright 2014 Facebook, Inc.
+ * Copyright 2017 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* limitations under the License.
*/
-#ifndef FOLLY_FORMAT_H_
+#pragma once
#define FOLLY_FORMAT_H_
-#include <array>
#include <cstdio>
#include <tuple>
#include <type_traits>
-#include <vector>
-#include <deque>
-#include <map>
-#include <unordered_map>
-
-#include <double-conversion.h>
-
-#include "folly/FBVector.h"
-#include "folly/Conv.h"
-#include "folly/Range.h"
-#include "folly/Traits.h"
-#include "folly/Likely.h"
-#include "folly/String.h"
-#include "folly/small_vector.h"
-#include "folly/FormatArg.h"
+
+#include <folly/Conv.h>
+#include <folly/FormatArg.h>
+#include <folly/Range.h>
+#include <folly/String.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 {
// forward declarations
-template <bool containerMode, class... Args> class Formatter;
+template <bool containerMode, class... Args>
+class Formatter;
template <class... Args>
Formatter<false, Args...> format(StringPiece fmt, Args&&... args);
template <class C>
Formatter<true, C> vformat(StringPiece fmt, C&& container);
-template <class T, class Enable=void> class FormatValue;
+template <class T, class Enable = void>
+class FormatValue;
+
+// 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.
*/
-template <bool containerMode, class... Args>
-class Formatter {
+/* 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 {
public:
- /*
- * Change whether or not Formatter should crash or throw exceptions if the
- * format string is invalid.
- *
- * Crashing is desirable for literal format strings that are fixed at compile
- * time. Errors in the format string are generally programmer bugs, and
- * should be caught early on in development. Crashing helps ensure these
- * problems are noticed.
- */
- void setCrashOnError(bool crash) {
- crashOnError_ = crash;
- }
-
/**
* Append to output. out(StringPiece sp) may be called (more than once)
*/
* Append to a string.
*/
template <class Str>
- typename std::enable_if<IsSomeString<Str>::value>::type
- appendTo(Str& str) const {
- auto appender = [&str] (StringPiece s) { str.append(s.data(), s.size()); };
+ typename std::enable_if<IsSomeString<Str>::value>::type appendTo(
+ Str& str) const {
+ auto appender = [&str](StringPiece s) { str.append(s.data(), s.size()); };
(*this)(appender);
}
return s;
}
- private:
- explicit Formatter(StringPiece str, Args&&... args);
-
- // Not copyable
- Formatter(const Formatter&) = delete;
- Formatter& operator=(const Formatter&) = delete;
-
- // Movable, but the move constructor and assignment operator are private,
- // 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)
- Formatter(Formatter&&) = default;
- Formatter& operator=(Formatter&&) = default;
+ /**
+ * Metadata to identify generated children of BaseFormatter
+ */
+ typedef detail::FormatterTag IsFormatter;
+ typedef BaseFormatter BaseType;
- typedef std::tuple<FormatValue<
- typename std::decay<Args>::type>...> ValueTuple;
+ private:
+ typedef std::tuple<Args...> ValueTuple;
static constexpr size_t valueCount = std::tuple_size<ValueTuple>::value;
- void handleFormatStrError() const FOLLY_NORETURN;
- template <class Output>
- void appendOutput(Output& out) const;
+ 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 {
+ doFormatFrom(size_t i, FormatArg& arg, Callback& /*cb*/) const {
arg.error("argument index out of range, max=", i);
}
typename std::enable_if<(K < valueCount)>::type
doFormatFrom(size_t i, FormatArg& arg, Callback& cb) const {
if (i == K) {
- std::get<K>(values_).format(arg, cb);
+ asDerived().template doFormatArg<K>(arg, cb);
} else {
- doFormatFrom<K+1>(i, arg, cb);
+ doFormatFrom<K + 1>(i, arg, cb);
}
}
return doFormatFrom<0>(i, arg, cb);
}
+ template <size_t K>
+ typename std::enable_if<K == valueCount, int>::type getSizeArgFrom(
+ size_t i,
+ const FormatArg& arg) const {
+ arg.error("argument index out of range, max=", i);
+ }
+
+ template <class T>
+ typename std::enable_if<
+ std::is_integral<T>::value && !std::is_same<T, bool>::value,
+ int>::type
+ getValue(const FormatValue<T>& format, const FormatArg&) const {
+ return static_cast<int>(format.getValue());
+ }
+
+ template <class T>
+ typename std::enable_if<
+ !std::is_integral<T>::value || std::is_same<T, bool>::value,
+ int>::type
+ getValue(const FormatValue<T>&, const FormatArg& arg) const {
+ arg.error("dynamic field width argument must be integral");
+ }
+
+ template <size_t K>
+ typename std::enable_if <
+ K<valueCount, int>::type getSizeArgFrom(size_t i, const FormatArg& arg)
+ const {
+ if (i == K) {
+ return getValue(getFormatValue<K>(), arg);
+ }
+ return getSizeArgFrom<K + 1>(i, arg);
+ }
+
+ int getSizeArg(size_t i, const FormatArg& arg) const {
+ return getSizeArgFrom<0>(i, arg);
+ }
+
StringPiece str_;
+
+ protected:
+ explicit BaseFormatter(StringPiece str, Args&&... args);
+
+ // Not copyable
+ BaseFormatter(const BaseFormatter&) = delete;
+ BaseFormatter& operator=(const BaseFormatter&) = delete;
+
+ // Movable, but the move constructor and assignment operator are private,
+ // 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 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_;
- bool crashOnError_{true};
+};
+
+template <bool containerMode, class... Args>
+class Formatter : public BaseFormatter<
+ Formatter<containerMode, Args...>,
+ containerMode,
+ Args...> {
+ private:
+ explicit Formatter(StringPiece& str, Args&&... args)
+ : BaseFormatter<
+ Formatter<containerMode, Args...>,
+ containerMode,
+ 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 {
+ this->template getFormatValue<K>().format(arg, cb);
+ }
+
+ friend class BaseFormatter<
+ Formatter<containerMode, Args...>,
+ containerMode,
+ Args...>;
template <class... A>
friend Formatter<false, A...> format(StringPiece fmt, A&&... arg);
- template <class... A>
- friend Formatter<false, A...> formatChecked(StringPiece fmt, A&&... arg);
template <class C>
friend Formatter<true, C> vformat(StringPiece fmt, C&& container);
- template <class C>
- friend Formatter<true, C> vformatChecked(StringPiece fmt, C&& container);
};
/**
* Formatter objects can be written to streams.
*/
-template<bool containerMode, class... Args>
-std::ostream& operator<<(std::ostream& out,
- const Formatter<containerMode, Args...>& formatter) {
- auto writer = [&out] (StringPiece sp) { out.write(sp.data(), sp.size()); };
+template <bool containerMode, class... Args>
+std::ostream& operator<<(
+ std::ostream& out,
+ const Formatter<containerMode, Args...>& formatter) {
+ auto writer = [&out](StringPiece sp) {
+ out.write(sp.data(), std::streamsize(sp.size()));
+ };
formatter(writer);
return out;
}
/**
* Formatter objects can be written to stdio FILEs.
*/
-template<bool containerMode, class... Args>
-void writeTo(FILE* fp, const Formatter<containerMode, Args...>& formatter);
+template <class Derived, bool containerMode, class... Args>
+void writeTo(
+ FILE* fp,
+ const BaseFormatter<Derived, containerMode, Args...>& formatter);
/**
* Create a formatter object.
* std::string formatted = format("{} {}", 23, 42).str();
* LOG(INFO) << format("{} {}", 23, 42);
* writeTo(stdout, format("{} {}", 23, 42));
- *
- * Note that format() will crash the program if the format string is invalid.
- * Normally, the format string is a fixed string literal specified by the
- * programmer. Invalid format strings are normally programmer bugs, and should
- * be caught early on during development. Crashing helps ensure these bugs are
- * found.
- *
- * Use formatChecked() if you have a dynamic format string (for example, a user
- * supplied value). formatChecked() will throw an exception rather than
- * crashing the program.
*/
template <class... Args>
Formatter<false, Args...> format(StringPiece fmt, Args&&... args) {
- return Formatter<false, Args...>(
- fmt, std::forward<Args>(args)...);
+ return Formatter<false, Args...>(fmt, std::forward<Args>(args)...);
}
/**
- * Create a formatter object from a dynamic format string.
- *
- * This is identical to format(), but throws an exception if the format string
- * is invalid, rather than aborting the program. This allows it to be used
- * with user-specified format strings which are not guaranteed to be well
- * formed.
+ * Like format(), but immediately returns the formatted string instead of an
+ * intermediate format object.
*/
template <class... Args>
-Formatter<false, Args...> formatChecked(StringPiece fmt, Args&&... args) {
- Formatter<false, Args...> f(fmt, std::forward<Args>(args)...);
- f.setCrashOnError(false);
- return f;
+inline std::string sformat(StringPiece fmt, Args&&... args) {
+ return format(fmt, std::forward<Args>(args)...).str();
}
/**
*/
template <class Container>
Formatter<true, Container> vformat(StringPiece fmt, Container&& container) {
- return Formatter<true, Container>(
- fmt, std::forward<Container>(container));
+ return Formatter<true, Container>(fmt, std::forward<Container>(container));
}
/**
- * Create a formatter object from a dynamic format string.
- *
- * This is identical to vformat(), but throws an exception if the format string
- * is invalid, rather than aborting the program. This allows it to be used
- * with user-specified format strings which are not guaranteed to be well
- * formed.
+ * Like vformat(), but immediately returns the formatted string instead of an
+ * intermediate format object.
*/
template <class Container>
-Formatter<true, Container> vformatChecked(StringPiece fmt,
- Container&& container) {
- Formatter<true, Container> f(fmt, std::forward<Container>(container));
- f.setCrashOnError(false);
- return f;
+inline std::string svformat(StringPiece fmt, Container&& container) {
+ return vformat(fmt, std::forward<Container>(container)).str();
+}
+
+/**
+ * Wrap a sequence or associative container so that out-of-range lookups
+ * return a default value rather than throwing an exception.
+ *
+ * Usage:
+ * format("[no_such_key"], defaulted(map, 42)) -> 42
+ */
+namespace detail {
+template <class Container, class Value>
+struct DefaultValueWrapper {
+ DefaultValueWrapper(const Container& container, const Value& defaultValue)
+ : container(container), defaultValue(defaultValue) {}
+
+ const Container& container;
+ const Value& defaultValue;
+};
+} // namespace detail
+
+template <class Container, class Value>
+detail::DefaultValueWrapper<Container, Value> defaulted(
+ const Container& c,
+ const Value& v) {
+ return detail::DefaultValueWrapper<Container, Value>(c, v);
}
/**
* field width")
*/
template <class FormatCallback>
-void formatNumber(StringPiece val, int prefixLen, FormatArg& arg,
- FormatCallback& cb);
-
+void formatNumber(
+ StringPiece val,
+ int prefixLen,
+ FormatArg& arg,
+ FormatCallback& cb);
/**
* Format a Formatter object recursively. Behaves just like
* formatString(fmt.str(), arg, cb); but avoids creating a temporary
* string if possible.
*/
-template <class FormatCallback, bool containerMode, class... Args>
-void formatFormatter(const Formatter<containerMode, Args...>& formatter,
- FormatArg& arg,
- FormatCallback& cb);
-
-} // namespace format_value
+template <
+ class FormatCallback,
+ class Derived,
+ bool containerMode,
+ class... Args>
+void formatFormatter(
+ const BaseFormatter<Derived, containerMode, Args...>& formatter,
+ FormatArg& arg,
+ FormatCallback& cb);
+
+} // namespace format_value
/*
* Specialize folly::FormatValue for your type.
* empty string)
*/
-} // namespace folly
+namespace detail {
+
+template <class T, class Enable = void>
+struct IsFormatter : public std::false_type {};
+
+template <class T>
+struct IsFormatter<
+ T,
+ typename std::enable_if<
+ std::is_same<typename T::IsFormatter, detail::FormatterTag>::value>::
+ type> : public std::true_type {};
+} // namespace detail
+
+// Deprecated API. formatChecked() et. al. now behave identically to their
+// non-Checked counterparts.
+template <class... Args>
+Formatter<false, Args...> formatChecked(StringPiece fmt, Args&&... args) {
+ return format(fmt, std::forward<Args>(args)...);
+}
+template <class... Args>
+inline std::string sformatChecked(StringPiece fmt, Args&&... args) {
+ return formatChecked(fmt, std::forward<Args>(args)...).str();
+}
+template <class Container>
+Formatter<true, Container> vformatChecked(
+ StringPiece fmt,
+ Container&& container) {
+ return vformat(fmt, std::forward<Container>(container));
+}
+template <class Container>
+inline std::string svformatChecked(StringPiece fmt, Container&& container) {
+ return vformatChecked(fmt, std::forward<Container>(container)).str();
+}
+template <class Str, class... Args>
+typename std::enable_if<IsSomeString<Str>::value>::type
+formatChecked(Str* out, StringPiece fmt, Args&&... args) {
+ formatChecked(fmt, std::forward<Args>(args)...).appendTo(*out);
+}
+template <class Str, class Container>
+typename std::enable_if<IsSomeString<Str>::value>::type
+vformatChecked(Str* out, StringPiece fmt, Container&& container) {
+ vformatChecked(fmt, std::forward<Container>(container)).appendTo(*out);
+}
-#include "folly/Format-inl.h"
+} // namespace folly
-#pragma GCC diagnostic pop
+#include <folly/Format-inl.h>
-#endif /* FOLLY_FORMAT_H_ */
+FOLLY_POP_WARNING
projects / folly.git / blobdiff