Make SettingChange and StreamCharSourcemove constructors and assignment operators noexcept (#808)

The explicitly defaulted or implemented move constructors and assignment
operators are made "noexcept".

Bugfix:
* src/stream.cpp Stream::Stream() char_traits::int_type intro[4] is
  now aggregate-initialized (to zero) to avoid UB.

Minor changes:
* Using std::isinf() and std::signbit() instead of comparing for
  equality with infinity.
* src/streamcharsource.h: Added #include "stream.h".
* src/stream.h: Forward declaring "class StreamCharSource".
* Some implicit casting changed into static_cast's.

Signed-off-by: Ted Lyngmo <ted@lyncon.se>

include/yaml-cpp/emitter.h

@@ -164,13 +164,12 @@ inline Emitter& Emitter::WriteStreamable(T value) {
         std::isnan(value)) {
       special = true;
       stream << ".nan";
-    } else if (std::numeric_limits<T>::has_infinity) {
-      if (value == std::numeric_limits<T>::infinity()) {
-        special = true;
-        stream << ".inf";
-      } else if (value == -std::numeric_limits<T>::infinity()) {
+    } else if (std::numeric_limits<T>::has_infinity && std::isinf(value)) {
       special = true;
+      if (std::signbit(value)) {
         stream << "-.inf";
+      } else {
+        stream << ".inf";
       }
     }
   }

include/yaml-cpp/node/detail/impl.h

@@ -33,7 +33,7 @@ struct get_idx<Key,
   static node* get(std::vector<node*>& sequence, const Key& key,
                    shared_memory_holder pMemory) {
     if (key > sequence.size() || (key > 0 && !sequence[key - 1]->is_defined()))
-      return 0;
+      return nullptr;
     if (key == sequence.size())
       sequence.push_back(&pMemory->create_node());
     return sequence[key];

src/setting.h

@@ -7,12 +7,18 @@
 #pragma once
 #endif
 
+#include "yaml-cpp/noexcept.h"
 #include <memory>
 #include <utility>
 #include <vector>
 
 namespace YAML {
-class SettingChangeBase;
+
+class SettingChangeBase {
+ public:
+  virtual ~SettingChangeBase() = default;
+  virtual void pop() = 0;
+};
 
 template <typename T>
 class Setting {
@@ -28,12 +34,6 @@ class Setting {
   T m_value;
 };
 
-class SettingChangeBase {
- public:
-  virtual ~SettingChangeBase() = default;
-  virtual void pop() = 0;
-};
-
 template <typename T>
 class SettingChange : public SettingChangeBase {
  public:
@@ -64,16 +64,25 @@ class SettingChanges {
  public:
   SettingChanges() : m_settingChanges{} {}
   SettingChanges(const SettingChanges&) = delete;
-  SettingChanges(SettingChanges&&) = default;
+  SettingChanges(SettingChanges&&) YAML_CPP_NOEXCEPT = default;
   SettingChanges& operator=(const SettingChanges&) = delete;
+  SettingChanges& operator=(SettingChanges&& rhs) YAML_CPP_NOEXCEPT {
+    if (this == &rhs)
+      return *this;
+
+    clear();
+    std::swap(m_settingChanges, rhs.m_settingChanges);
+
+    return *this;
+  }
   ~SettingChanges() { clear(); }
 
-  void clear() {
+  void clear() YAML_CPP_NOEXCEPT {
     restore();
     m_settingChanges.clear();
   }
 
-  void restore() {
+  void restore() YAML_CPP_NOEXCEPT {
     for (setting_changes::const_iterator it = m_settingChanges.begin();
          it != m_settingChanges.end(); ++it)
       (*it)->pop();
@@ -83,19 +92,8 @@ class SettingChanges {
     m_settingChanges.push_back(std::move(pSettingChange));
   }
 
-  // like std::unique_ptr - assignment is transfer of ownership
-  SettingChanges& operator=(SettingChanges&& rhs) {
-    if (this == &rhs)
-      return *this;
-
-    clear();
-    std::swap(m_settingChanges, rhs.m_settingChanges);
-
-    return *this;
-  }
-
  private:
-  using setting_changes = std::vector<std::unique_ptr<SettingChangeBase> >;
+  using setting_changes = std::vector<std::unique_ptr<SettingChangeBase>>;
   setting_changes m_settingChanges;
 };
 }  // namespace YAML

src/stream.cpp

@@ -151,7 +151,7 @@ inline UtfIntroCharType IntroCharTypeOf(std::istream::int_type ch) {
 
 inline char Utf8Adjust(unsigned long ch, unsigned char lead_bits,
                        unsigned char rshift) {
-  const unsigned char header = ((1 << lead_bits) - 1) << (8 - lead_bits);
+  const unsigned char header = static_cast<unsigned char>(((1 << lead_bits) - 1) << (8 - lead_bits));
   const unsigned char mask = (0xFF >> (lead_bits + 1));
   return static_cast<char>(
       static_cast<unsigned char>(header | ((ch >> rshift) & mask)));
@@ -196,7 +196,7 @@ Stream::Stream(std::istream& input)
 
   // Determine (or guess) the character-set by reading the BOM, if any.  See
   // the YAML specification for the determination algorithm.
-  char_traits::int_type intro[4];
+  char_traits::int_type intro[4]{};
   int nIntroUsed = 0;
   UtfIntroState state = uis_start;
   for (; !s_introFinalState[state];) {
@@ -273,9 +273,11 @@ char Stream::get() {
 // . Extracts 'n' characters from the stream and updates our position
 std::string Stream::get(int n) {
   std::string ret;
-  ret.reserve(n);
+  if(n > 0) {
+    ret.reserve(static_cast<std::string::size_type>(n));
     for (int i = 0; i < n; i++)
       ret += get();
+  }
   return ret;
 }
 
@@ -326,7 +328,7 @@ bool Stream::_ReadAheadTo(size_t i) const {
 void Stream::StreamInUtf8() const {
   unsigned char b = GetNextByte();
   if (m_input.good()) {
-    m_readahead.push_back(b);
+    m_readahead.push_back(static_cast<char>(b));
   }
 }
 

src/stream.h

@@ -16,6 +16,9 @@
 #include <string>
 
 namespace YAML {
+
+class StreamCharSource;
+
 class Stream {
  public:
   friend class StreamCharSource;

src/streamcharsource.h

@@ -7,14 +7,17 @@
 #pragma once
 #endif
 
+#include "yaml-cpp/noexcept.h"
+#include "stream.h"
 #include <cstddef>
 
 namespace YAML {
+
 class StreamCharSource {
  public:
   StreamCharSource(const Stream& stream) : m_offset(0), m_stream(stream) {}
   StreamCharSource(const StreamCharSource& source) = default;
-  StreamCharSource(StreamCharSource&&) = default;
+  StreamCharSource(StreamCharSource&&) YAML_CPP_NOEXCEPT = default;
   StreamCharSource& operator=(const StreamCharSource&) = delete;
   StreamCharSource& operator=(StreamCharSource&&) = delete;
   ~StreamCharSource() = default;
@@ -37,7 +40,7 @@ inline StreamCharSource::operator bool() const {
 inline const StreamCharSource StreamCharSource::operator+(int i) const {
   StreamCharSource source(*this);
   if (static_cast<int>(source.m_offset) + i >= 0)
-    source.m_offset += i;
+    source.m_offset += static_cast<std::size_t>(i);
   else
     source.m_offset = 0;
   return source;