From: Yedidya Feldblum <yfeldblum@fb.com>
Date: Tue, 17 Oct 2017 03:10:35 +0000 (-0700)
Subject: Make Range.h and FBString.h mutually independent
X-Git-Tag: v2017.10.23.00~37
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=1d4de585b9bee671244190cf24df528c13b1fb06;p=folly.git

Make Range.h and FBString.h mutually independent

Summary:
[Folly] Make `Range.h` and `FBString.h` mutually independent.

This means that `Range` cannot directly know about `fbstring`, so any interactions between the two types must be indirected through templates.

Motivation: `FBString.h` is a relatively heaviweight `#include` for things that need `Range.h` but which do not use `fbstring`.

Reviewed By: ericniebler

Differential Revision: D6062434

fbshipit-source-id: e2f21c33f482eadffd0a8679eff4ece59bab53e9
---

diff --git a/folly/FBString.h b/folly/FBString.h
index 90728601..b566d119 100644
--- a/folly/FBString.h
+++ b/folly/FBString.h
@@ -2894,3 +2894,13 @@ FOLLY_POP_WARNING
 #undef FBSTRING_LIKELY
 #undef FBSTRING_UNLIKELY
 #undef FBSTRING_ASSERT
+
+#ifndef _LIBSTDCXX_FBSTRING
+namespace folly {
+template <class T>
+struct IsSomeString;
+
+template <>
+struct IsSomeString<fbstring> : std::true_type {};
+} // namespace folly
+#endif
diff --git a/folly/FixedString.h b/folly/FixedString.h
index 1465070c..732ae6ac 100644
--- a/folly/FixedString.h
+++ b/folly/FixedString.h
@@ -790,29 +790,6 @@ class BasicFixedString : private detail::fixedstring::FixedStringBase {
     return *this;
   }
 
-  /** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** **
-   * Conversion to folly::Range
-   * \return `Range<Iter>{begin(), end()}`
-   */
-  template <
-      class Iter,
-      class = typename std::enable_if<
-          std::is_convertible<Char*, Iter>::value>::type>
-  FOLLY_CPP14_CONSTEXPR /* implicit */ operator Range<Iter>() noexcept {
-    return {begin(), end()};
-  }
-
-  /**
-   * \overload
-   */
-  template <
-      class Iter,
-      class = typename std::enable_if<
-          std::is_convertible<const Char*, Iter>::value>::type>
-  constexpr /* implicit */ operator Range<Iter>() const noexcept {
-    return {begin(), end()};
-  }
-
   /** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** **
    * Conversion to folly::Range
    * \return `Range<Char*>{begin(), end()}`
diff --git a/folly/Format-inl.h b/folly/Format-inl.h
index 940224c2..60fdf245 100644
--- a/folly/Format-inl.h
+++ b/folly/Format-inl.h
@@ -931,7 +931,7 @@ template <>
 struct KeyFromStringPiece<fbstring> : public FormatTraitsBase {
   typedef fbstring key_type;
   static fbstring convert(StringPiece s) {
-    return s.toFbstring();
+    return s.to<fbstring>();
   }
 };
 
diff --git a/folly/IPAddressV4.h b/folly/IPAddressV4.h
index 4b0b8799..96de8add 100644
--- a/folly/IPAddressV4.h
+++ b/folly/IPAddressV4.h
@@ -22,6 +22,7 @@
 #include <functional>
 #include <iosfwd>
 
+#include <folly/FBString.h>
 #include <folly/Hash.h>
 #include <folly/Range.h>
 #include <folly/detail/IPAddress.h>
diff --git a/folly/IPAddressV6.h b/folly/IPAddressV6.h
index 23c19e50..f641bdcd 100644
--- a/folly/IPAddressV6.h
+++ b/folly/IPAddressV6.h
@@ -24,6 +24,7 @@
 #include <map>
 #include <stdexcept>
 
+#include <folly/FBString.h>
 #include <folly/Hash.h>
 #include <folly/Optional.h>
 #include <folly/Range.h>
diff --git a/folly/Range.h b/folly/Range.h
index d1fa497c..ce3e1fe8 100644
--- a/folly/Range.h
+++ b/folly/Range.h
@@ -19,7 +19,6 @@
 
 #pragma once
 
-#include <folly/FBString.h>
 #include <folly/Portability.h>
 #include <folly/hash/SpookyHashV2.h>
 #include <folly/portability/BitsFunctexcept.h>
@@ -30,6 +29,7 @@
 #include <glog/logging.h>
 #include <algorithm>
 #include <array>
+#include <cassert>
 #include <climits>
 #include <cstddef>
 #include <cstring>
@@ -38,17 +38,6 @@
 #include <string>
 #include <type_traits>
 
-// libc++ doesn't provide this header, nor does msvc
-#ifdef FOLLY_HAVE_BITS_CXXCONFIG_H
-// This file appears in two locations: inside fbcode and in the
-// libstdc++ source code (when embedding fbstring as std::string).
-// To aid in this schizophrenic use, two macros are defined in
-// c++config.h:
-//   _LIBSTDCXX_FBSTRING - Set inside libstdc++.  This is useful to
-//      gate use inside fbcode v. libstdc++
-#include <bits/c++config.h>
-#endif
-
 #include <folly/CpuId.h>
 #include <folly/Likely.h>
 #include <folly/Traits.h>
@@ -61,6 +50,15 @@ FOLLY_GCC_DISABLE_WARNING("-Wshadow")
 
 namespace folly {
 
+/**
+ * Ubiquitous helper template for knowing what's a string.
+ */
+template <class T>
+struct IsSomeString : std::false_type {};
+
+template <>
+struct IsSomeString<std::string> : std::true_type {};
+
 template <class Iter>
 class Range;
 
@@ -251,30 +249,58 @@ class Range : private boost::totally_ordered<Range<Iter>> {
   Range(const Range& other, size_type first, size_type length = npos)
       : Range(other.subpiece(first, length)) {}
 
-  template <class T = Iter, typename detail::IsCharPointer<T>::const_type = 0>
-  /* implicit */ Range(const fbstring& str)
-      : b_(str.data()), e_(b_ + str.size()) {}
+  template <
+      class Container,
+      class = typename std::enable_if<
+          std::is_same<Iter, typename Container::const_pointer>::value>::type,
+      class = decltype(
+          Iter(std::declval<Container const&>().data()),
+          Iter(
+              std::declval<Container const&>().data() +
+              std::declval<Container const&>().size()))>
+  /* implicit */ constexpr Range(Container const& container)
+      : b_(container.data()), e_(b_ + container.size()) {}
 
-  template <class T = Iter, typename detail::IsCharPointer<T>::const_type = 0>
-  Range(const fbstring& str, fbstring::size_type startFrom) {
-    if (UNLIKELY(startFrom > str.size())) {
+  template <
+      class Container,
+      class = typename std::enable_if<
+          std::is_same<Iter, typename Container::const_pointer>::value>::type,
+      class = decltype(
+          Iter(std::declval<Container const&>().data()),
+          Iter(
+              std::declval<Container const&>().data() +
+              std::declval<Container const&>().size()))>
+  Range(Container const& container, typename Container::size_type startFrom) {
+    auto const cdata = container.data();
+    auto const csize = container.size();
+    if (UNLIKELY(startFrom > csize)) {
       std::__throw_out_of_range("index out of range");
     }
-    b_ = str.data() + startFrom;
-    e_ = str.data() + str.size();
+    b_ = cdata + startFrom;
+    e_ = cdata + csize;
   }
 
-  template <class T = Iter, typename detail::IsCharPointer<T>::const_type = 0>
+  template <
+      class Container,
+      class = typename std::enable_if<
+          std::is_same<Iter, typename Container::const_pointer>::value>::type,
+      class = decltype(
+          Iter(std::declval<Container const&>().data()),
+          Iter(
+              std::declval<Container const&>().data() +
+              std::declval<Container const&>().size()))>
   Range(
-      const fbstring& str,
-      fbstring::size_type startFrom,
-      fbstring::size_type size) {
-    if (UNLIKELY(startFrom > str.size())) {
+      Container const& container,
+      typename Container::size_type startFrom,
+      typename Container::size_type size) {
+    auto const cdata = container.data();
+    auto const csize = container.size();
+    if (UNLIKELY(startFrom > csize)) {
       std::__throw_out_of_range("index out of range");
     }
-    b_ = str.data() + startFrom;
-    if (str.size() - startFrom < size) {
-      e_ = str.data() + str.size();
+    b_ = cdata + startFrom;
+    if (csize - startFrom < size) {
+      e_ = cdata + csize;
     } else {
       e_ = b_ + size;
     }
@@ -448,19 +474,22 @@ class Range : private boost::totally_ordered<Range<Iter>> {
     assert(b_ < e_);
     return detail::value_before(e_);
   }
-  // Works only for Range<const char*> and Range<char*>
-  std::string str() const {
-    return std::string(b_, size());
-  }
-  std::string toString() const {
-    return str();
+
+  template <typename Tgt>
+  auto to() const
+      -> decltype(Tgt(std::declval<Iter const&>(), std::declval<size_type>())) {
+    return Tgt(b_, size());
   }
   // Works only for Range<const char*> and Range<char*>
-  fbstring fbstr() const {
-    return fbstring(b_, size());
+  template <typename Tgt = std::string>
+  auto str() const
+      -> decltype(Tgt(std::declval<Iter const&>(), std::declval<size_type>())) {
+    return to<Tgt>();
   }
-  fbstring toFbstring() const {
-    return fbstr();
+  template <typename Tgt = std::string>
+  auto toString() const
+      -> decltype(Tgt(std::declval<Iter const&>(), std::declval<size_type>())) {
+    return to<Tgt>();
   }
 
   const_range_type castToConst() const {
@@ -1314,17 +1343,6 @@ struct hasher<
   }
 };
 
-/**
- * Ubiquitous helper template for knowing what's a string
- */
-template <class T>
-struct IsSomeString {
-  enum {
-    value =
-        std::is_same<T, std::string>::value || std::is_same<T, fbstring>::value
-  };
-};
-
 /**
  * _sp is a user-defined literal suffix to make an appropriate Range
  * specialization from a literal string.
diff --git a/folly/ThreadName.cpp b/folly/ThreadName.cpp
index 919a0112..ed11c10e 100644
--- a/folly/ThreadName.cpp
+++ b/folly/ThreadName.cpp
@@ -102,15 +102,20 @@ bool setThreadName(std::thread::id tid, StringPiece name) {
 #if !FOLLY_HAVE_PTHREAD || _WIN32
   return false;
 #else
-  auto trimmedName = name.fbstr().substr(0, kMaxThreadNameLength - 1);
+  auto const piece = name.subpiece(0, kMaxThreadNameLength - 1);
+  auto const data = piece.data();
+  auto const size = piece.size();
+  char trimmedName[kMaxThreadNameLength];
+  std::memcpy(trimmedName, data, size);
+  std::memset(trimmedName + size, 0, kMaxThreadNameLength - size);
   auto id = stdTidToPthreadId(tid);
 #if FOLLY_HAS_PTHREAD_SETNAME_NP_THREAD_NAME
-  return 0 == pthread_setname_np(id, trimmedName.c_str());
+  return 0 == pthread_setname_np(id, const_cast<char const*>(trimmedName));
 #elif FOLLY_HAS_PTHREAD_SETNAME_NP_NAME
   // Since OS X 10.6 it is possible for a thread to set its own name,
   // but not that of some other thread.
   if (pthread_equal(pthread_self(), id)) {
-    return 0 == pthread_setname_np(trimmedName.c_str());
+    return 0 == pthread_setname_np(const_cast<char const*>(trimmedName));
   }
   return false;
 #else