/*
- * Copyright 2013 Facebook, Inc.
+ * Copyright 2014 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
#ifndef FOLLY_BASE_CONV_H_
#define FOLLY_BASE_CONV_H_
-#include "folly/FBString.h"
-#include "folly/Likely.h"
-#include "folly/Preprocessor.h"
-#include "folly/Range.h"
+#include <folly/FBString.h>
+#include <folly/Likely.h>
+#include <folly/Preprocessor.h>
+#include <folly/Range.h>
#include <boost/implicit_cast.hpp>
#include <type_traits>
#include <limits.h>
-#include "double-conversion.h" // V8 JavaScript implementation
+// V8 JavaScript implementation
+#include <double-conversion/double-conversion.h>
#define FOLLY_RANGE_CHECK(condition, message) \
((condition) ? (void)0 : throw std::range_error( \
namespace detail {
-template <class T> struct IsSomeString {
- enum { value = std::is_same<T, std::string>::value
- || std::is_same<T, fbstring>::value };
-};
-
template <class T>
const T& getLastElement(const T & v) {
return v;
return getLastElement(vs...);
}
+// This class exists to specialize away std::tuple_element in the case where we
+// have 0 template arguments. Without this, Clang/libc++ will blow a
+// static_assert even if tuple_element is protected by an enable_if.
+template <class... Ts>
+struct last_element {
+ typedef typename std::enable_if<
+ sizeof...(Ts) >= 1,
+ typename std::tuple_element<
+ sizeof...(Ts) - 1, std::tuple<Ts...>
+ >::type>::type type;
+};
+
+template <>
+struct last_element<> {
+ typedef void type;
+};
+
} // namespace detail
/*******************************************************************************
*result += value;
}
+/**
+ * Ubiquitous helper template for writing string appenders
+ */
+template <class T> struct IsSomeString {
+ enum { value = std::is_same<T, std::string>::value
+ || std::is_same<T, fbstring>::value };
+};
+
/**
* Everything implicitly convertible to const char* gets appended.
*/
template <class Tgt, class Src>
typename std::enable_if<
std::is_convertible<Src, const char*>::value
- && detail::IsSomeString<Tgt>::value>::type
+ && IsSomeString<Tgt>::value>::type
toAppend(Src value, Tgt * result) {
// Treat null pointers like an empty string, as in:
// operator<<(std::ostream&, const char*).
*/
template <class Tgt, class Src>
typename std::enable_if<
- detail::IsSomeString<Src>::value && detail::IsSomeString<Tgt>::value>::type
+ IsSomeString<Src>::value && IsSomeString<Tgt>::value>::type
toAppend(const Src& value, Tgt * result) {
result->append(value);
}
*/
template <class Tgt>
typename std::enable_if<
- detail::IsSomeString<Tgt>::value>::type
+ IsSomeString<Tgt>::value>::type
toAppend(StringPiece value, Tgt * result) {
result->append(value.data(), value.size());
}
*/
template <class Tgt>
typename std::enable_if<
- detail::IsSomeString<Tgt>::value>::type
+ IsSomeString<Tgt>::value>::type
toAppend(const fbstring& value, Tgt * result) {
result->append(value.data(), value.size());
}
template <class Tgt, class Src>
typename std::enable_if<
std::is_integral<Src>::value && std::is_signed<Src>::value &&
- detail::IsSomeString<Tgt>::value && sizeof(Src) >= 4>::type
+ IsSomeString<Tgt>::value && sizeof(Src) >= 4>::type
toAppend(Src value, Tgt * result) {
char buffer[20];
if (value < 0) {
template <class Tgt, class Src>
typename std::enable_if<
std::is_integral<Src>::value && !std::is_signed<Src>::value
- && detail::IsSomeString<Tgt>::value && sizeof(Src) >= 4>::type
+ && IsSomeString<Tgt>::value && sizeof(Src) >= 4>::type
toAppend(Src value, Tgt * result) {
char buffer[20];
result->append(buffer, buffer + uint64ToBufferUnsafe(value, buffer));
template <class Tgt, class Src>
typename std::enable_if<
std::is_integral<Src>::value
- && detail::IsSomeString<Tgt>::value && sizeof(Src) < 4>::type
+ && IsSomeString<Tgt>::value && sizeof(Src) < 4>::type
toAppend(Src value, Tgt * result) {
typedef typename
std::conditional<std::is_signed<Src>::value, int64_t, uint64_t>::type
toAppend<Tgt>(static_cast<Intermediate>(value), result);
}
-#if defined(__GNUC__) && __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 7)
+#if defined(__clang__) || __GNUC_PREREQ(4, 7)
// std::underlying_type became available by gcc 4.7.0
/**
*/
template <class Tgt, class Src>
typename std::enable_if<
- std::is_enum<Src>::value && detail::IsSomeString<Tgt>::value>::type
+ std::is_enum<Src>::value && IsSomeString<Tgt>::value>::type
toAppend(Src value, Tgt * result) {
toAppend(
static_cast<typename std::underlying_type<Src>::type>(value), result);
*/
template <class Tgt, class Src>
typename std::enable_if<
- std::is_enum<Src>::value && detail::IsSomeString<Tgt>::value>::type
+ std::is_enum<Src>::value && IsSomeString<Tgt>::value>::type
toAppend(Src value, Tgt * result) {
/* static */ if (Src(-1) < 0) {
/* static */ if (sizeof(Src) <= sizeof(int)) {
template <class Tgt, class Src>
typename std::enable_if<
std::is_floating_point<Src>::value
- && detail::IsSomeString<Tgt>::value>::type
+ && IsSomeString<Tgt>::value>::type
toAppend(
Src value,
Tgt * result,
template <class Tgt, class Src>
typename std::enable_if<
std::is_floating_point<Src>::value
- && detail::IsSomeString<Tgt>::value>::type
+ && IsSomeString<Tgt>::value>::type
toAppend(Src value, Tgt * result) {
toAppend(
value, result, double_conversion::DoubleToStringConverter::SHORTEST, 0);
*/
template <class T, class... Ts>
typename std::enable_if<sizeof...(Ts) >= 2
- && detail::IsSomeString<
+ && IsSomeString<
typename std::remove_pointer<
- typename std::tuple_element<
- sizeof...(Ts) - 1, std::tuple<Ts...>
- >::type>::type>::value>::type
+ typename detail::last_element<Ts...>::type
+ >::type>::value>::type
toAppend(const T& v, const Ts&... vs) {
toAppend(v, detail::getLastElement(vs...));
toAppend(vs...);
* Variadic base case: do nothing.
*/
template <class Tgt>
-typename std::enable_if<detail::IsSomeString<Tgt>::value>::type
+typename std::enable_if<IsSomeString<Tgt>::value>::type
toAppend(Tgt* result) {
}
* Variadic base case: do nothing.
*/
template <class Delimiter, class Tgt>
-typename std::enable_if<detail::IsSomeString<Tgt>::value>::type
+typename std::enable_if<IsSomeString<Tgt>::value>::type
toAppendDelim(const Delimiter& delim, Tgt* result) {
}
* 1 element: same as toAppend.
*/
template <class Delimiter, class T, class Tgt>
-typename std::enable_if<detail::IsSomeString<Tgt>::value>::type
+typename std::enable_if<IsSomeString<Tgt>::value>::type
toAppendDelim(const Delimiter& delim, const T& v, Tgt* tgt) {
toAppend(v, tgt);
}
*/
template <class Delimiter, class T, class... Ts>
typename std::enable_if<sizeof...(Ts) >= 2
- && detail::IsSomeString<
+ && IsSomeString<
typename std::remove_pointer<
- typename std::tuple_element<
- sizeof...(Ts) - 1, std::tuple<Ts...>
- >::type>::type>::value>::type
+ typename detail::last_element<Ts...>::type
+ >::type>::value>::type
toAppendDelim(const Delimiter& delim, const T& v, const Ts&... vs) {
toAppend(v, delim, detail::getLastElement(vs...));
toAppendDelim(delim, vs...);
}
+/**
+ * to<SomeString>(SomeString str) returns itself. As both std::string and
+ * folly::fbstring use Copy-on-Write, it's much more efficient by
+ * avoiding copying the underlying char array.
+ */
+template <class Tgt, class Src>
+typename std::enable_if<
+ IsSomeString<Tgt>::value && std::is_same<Tgt, Src>::value,
+ Tgt>::type
+to(const Src & value) {
+ return value;
+}
+
/**
* to<SomeString>(v1, v2, ...) uses toAppend() (see below) as back-end
* for all types.
*/
template <class Tgt, class... Ts>
-typename std::enable_if<detail::IsSomeString<Tgt>::value, Tgt>::type
+typename std::enable_if<
+ IsSomeString<Tgt>::value && (
+ sizeof...(Ts) != 1 ||
+ !std::is_same<Tgt, typename detail::last_element<Ts...>::type>::value),
+ Tgt>::type
to(const Ts&... vs) {
Tgt result;
toAppend(vs..., &result);
return result;
}
+/**
+ * toDelim<SomeString>(SomeString str) returns itself.
+ */
+template <class Tgt, class Delim, class Src>
+typename std::enable_if<
+ IsSomeString<Tgt>::value && std::is_same<Tgt, Src>::value,
+ Tgt>::type
+toDelim(const Delim& delim, const Src & value) {
+ return value;
+}
+
/**
* toDelim<SomeString>(delim, v1, v2, ...) uses toAppendDelim() as
* back-end for all types.
*/
template <class Tgt, class Delim, class... Ts>
-typename std::enable_if<detail::IsSomeString<Tgt>::value, Tgt>::type
+typename std::enable_if<
+ IsSomeString<Tgt>::value && (
+ sizeof...(Ts) != 1 ||
+ !std::is_same<Tgt, typename detail::last_element<Ts...>::type>::value),
+ Tgt>::type
toDelim(const Delim& delim, const Ts&... vs) {
Tgt result;
toAppendDelim(delim, vs..., &result);
auto t = detail::digits_to<typename std::make_unsigned<Tgt>::type>(b, m);
if (negative) {
result = -t;
- FOLLY_RANGE_CHECK(result <= 0, "Negative overflow");
+ FOLLY_RANGE_CHECK(is_non_positive(result), "Negative overflow");
} else {
result = t;
- FOLLY_RANGE_CHECK(result >= 0, "Overflow");
+ FOLLY_RANGE_CHECK(is_non_negative(result), "Overflow");
}
}
src->advance(m - src->data());
* Enum to anything and back
******************************************************************************/
-#if defined(__GNUC__) && __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 7)
+#if defined(__clang__) || __GNUC_PREREQ(4, 7)
// std::underlying_type became available by gcc 4.7.0
template <class Tgt, class Src>
projects / folly.git / blobdiff