Only automatically convert json objects to other types when they are uninitialized

Originally committed to SVN as r6005.

aegisub/libaegisub/common/cajun/elements.cpp

@@ -14,32 +14,40 @@ Author: Terry Caton
 #include <cassert>
 #endif
 
+namespace {
+	using namespace json;
+
+	class CastVisitorBase : public Visitor, public ConstVisitor {
+		void Visit(Array&) { }
+		void Visit(Object&) { }
+		void Visit(Number&) { }
+		void Visit(String&) { }
+		void Visit(Boolean&) { }
+		void Visit(Null&) { is_null = true; }
+		void Visit(Array const&) { }
+		void Visit(Object const&) { }
+		void Visit(Number const&) { }
+		void Visit(String const&) { }
+		void Visit(Boolean const&) { }
+		void Visit(Null const&) { is_null = true; }
+	public:
+		bool is_null;
+		CastVisitorBase() : is_null(false) { }
+	};
+
+	template<class T>
+	struct CastVisitor : public CastVisitorBase {
+		T *element;
+		CastVisitor() : element(0) { }
+		void Visit(T& ele) { element = &ele; }
+	};
+}
+
 namespace json
 {
 
 /////////////////////////
 // UnknownElement members
-class CastVisitor : public ConstVisitor
-{
-   virtual void Visit(const Array&) { }
-   virtual void Visit(const Object&) { }
-   virtual void Visit(const Number&) { }
-   virtual void Visit(const String&) { }
-   virtual void Visit(const Boolean&) { }
-   virtual void Visit(const Null&) { }
-};
-
-template <typename ElementTypeT>
-class CastVisitor_T : public CastVisitor
-{
-public:
-   const ElementTypeT *element;
-   CastVisitor_T() : element(0) { }
-
-   // we don't know what this is, but it overrides one of the base's no-op functions
-   void Visit(const ElementTypeT& element) { this->element = &element; }
-};
-
 class UnknownElement::Imp
 {
 public:
@@ -57,15 +65,15 @@ template <typename ElementTypeT>
 class UnknownElement::Imp_T : public UnknownElement::Imp
 {
 public:
-   Imp_T(const ElementTypeT& element) : m_Element(element) {}
+   Imp_T(const ElementTypeT& element) : m_Element(element) { }
-   virtual Imp* Clone() const { return new Imp_T<ElementTypeT>(*this); }
+   Imp* Clone() const { return new Imp_T<ElementTypeT>(*this); }
 
-   virtual void Accept(ConstVisitor& visitor) const { visitor.Visit(m_Element); }
+   void Accept(ConstVisitor& visitor) const { visitor.Visit(m_Element); }
-   virtual void Accept(Visitor& visitor) { visitor.Visit(m_Element); }
+   void Accept(Visitor& visitor)            { visitor.Visit(m_Element); }
 
-   virtual bool Compare(const Imp& imp) const
+   bool Compare(const Imp& imp) const
    {
-      CastVisitor_T<ElementTypeT> castVisitor;
+      CastVisitor<const ElementTypeT> castVisitor;
       imp.Accept(castVisitor);
       return castVisitor.element && m_Element == *castVisitor.element;
    }
@@ -88,31 +96,30 @@ UnknownElement::UnknownElement(const Null& null) :               m_pImp( new Imp
 
 UnknownElement::~UnknownElement()   { delete m_pImp; }
 
-UnknownElement::operator const Object& () const  { return CastTo<Object>(); }
+UnknownElement::operator Object const&()  const { return CastTo<Object>(); }
-UnknownElement::operator const Array& () const   { return CastTo<Array>(); }
+UnknownElement::operator Array const&()   const { return CastTo<Array>(); }
-UnknownElement::operator const Number& () const  { return CastTo<Number>(); }
+UnknownElement::operator Number const&()  const { return CastTo<Number>(); }
-UnknownElement::operator const Boolean& () const { return CastTo<Boolean>(); }
+UnknownElement::operator Boolean const&() const { return CastTo<Boolean>(); }
-UnknownElement::operator const String& () const  { return CastTo<String>(); }
+UnknownElement::operator String const&()  const { return CastTo<String>(); }
-UnknownElement::operator const Null& () const    { return CastTo<Null>(); }
+UnknownElement::operator Null const&()    const { return CastTo<Null>(); }
 
-UnknownElement::operator Object& ()  { return ConvertTo<Object>(); }
+UnknownElement::operator Object&()  { return CastTo<Object>(); }
-UnknownElement::operator Array& ()   { return ConvertTo<Array>(); }
+UnknownElement::operator Array&()   { return CastTo<Array>(); }
-UnknownElement::operator Number& ()  { return ConvertTo<Number>(); }
+UnknownElement::operator Number&()  { return CastTo<Number>(); }
-UnknownElement::operator Boolean& () { return ConvertTo<Boolean>(); }
+UnknownElement::operator Boolean&() { return CastTo<Boolean>(); }
-UnknownElement::operator String& ()  { return ConvertTo<String>(); }
+UnknownElement::operator String&()  { return CastTo<String>(); }
-UnknownElement::operator Null& ()    { return ConvertTo<Null>(); }
+UnknownElement::operator Null&()    { return CastTo<Null>(); }
 
-UnknownElement& UnknownElement::operator = (const UnknownElement& unknown)
+UnknownElement& UnknownElement::operator =(const UnknownElement& unknown)
 {
    delete m_pImp;
    m_pImp = unknown.m_pImp->Clone();
    return *this;
 }
 
-UnknownElement& UnknownElement::operator[] (const std::string& key)
+UnknownElement& UnknownElement::operator[](const std::string& key)
 {
-   // the people want an object. make us one if we aren't already
+   return CastTo<Object>()[key];
-   return ConvertTo<Object>()[key];
 }
 
 const UnknownElement& UnknownElement::operator[] (const std::string& key) const
@@ -125,23 +132,14 @@ const UnknownElement& UnknownElement::operator[] (const std::string& key) const
    return it->second;
 }
 
-UnknownElement& UnknownElement::operator[] (size_t index)
+UnknownElement&       UnknownElement::operator[](size_t index)       { return CastTo<Array>()[index]; }
-{
+UnknownElement const& UnknownElement::operator[](size_t index) const { return CastTo<Array>()[index]; }
-   // the people want an array. make us one if we aren't already
-   return ConvertTo<Array>()[index];
-}
-
-const UnknownElement& UnknownElement::operator[] (size_t index) const
-{
-   // throws if we aren't an array
-   return CastTo<Array>()[index];
-}
 
 
 template <typename ElementTypeT>
-const ElementTypeT& UnknownElement::CastTo() const
+ElementTypeT const& UnknownElement::CastTo() const
 {
-   CastVisitor_T<ElementTypeT> castVisitor;
+   CastVisitor<const ElementTypeT> castVisitor;
    m_pImp->Accept(castVisitor);
    if (!castVisitor.element)
       throw Exception("Bad cast");
@@ -149,17 +147,21 @@ const ElementTypeT& UnknownElement::CastTo() const
 }
 
 template <typename ElementTypeT>
-ElementTypeT& UnknownElement::ConvertTo()
+ElementTypeT& UnknownElement::CastTo()
 {
-   CastVisitor_T<ElementTypeT> castVisitor;
+   CastVisitor<ElementTypeT> castVisitor;
    Accept(castVisitor);
-   if (!castVisitor.element)
+
-   {
+   // If this element is uninitialized, implicitly convert it to the desired type
-      // we're not the right type. fix it & try again
+   if (castVisitor.is_null) {
       *this = ElementTypeT();
+      return *this;
    }
 
-   return *this;
+   // Otherwise throw an exception
+   if (!castVisitor.element)
+      throw Exception("Bad cast");
+   return *castVisitor.element;
 }
 
 void UnknownElement::Accept(ConstVisitor& visitor) const { m_pImp->Accept(visitor); }

aegisub/libaegisub/common/cajun/reader.cpp

@@ -123,7 +123,7 @@ void Reader::Read_i(ElementTypeT& element, std::istream& istr)
    reader.Scan(tokens, inputStream);
 
    TokenStream tokenStream(tokens);
-   reader.Parse(element, tokenStream);
+   element = reader.Parse(tokenStream);
 
    if (!tokenStream.EOS())
    {
@@ -304,131 +304,79 @@ void Reader::MatchNumber(std::string& sNumber, InputStream& inputStream)
 }
 
 
-void Reader::Parse(UnknownElement& element, Reader::TokenStream& tokenStream)
+UnknownElement Reader::Parse(Reader::TokenStream& tokenStream)
 {
-   if (tokenStream.EOS()) {
+   if (tokenStream.EOS())
       throw ParseException("Unexpected end of token stream", Location(), Location()); // nowhere to point to
-   }
 
-   const Token& token = tokenStream.Peek();
+   Token const& token = tokenStream.Peek();
    switch (token.nType) {
-      case Token::TOKEN_OBJECT_BEGIN:
+      case Token::TOKEN_OBJECT_BEGIN: return ParseObject(tokenStream);
-      {
+      case Token::TOKEN_ARRAY_BEGIN:  return ParseArray(tokenStream);
-         // implicit non-const cast will perform conversion for us (if necessary)
+      case Token::TOKEN_STRING:       return ParseString(tokenStream);
-         Object& object = element;
+      case Token::TOKEN_NUMBER:       return ParseNumber(tokenStream);
-         Parse(object, tokenStream);
+      case Token::TOKEN_BOOLEAN:      return ParseBoolean(tokenStream);
-         break;
+      case Token::TOKEN_NULL:         return ParseNull(tokenStream);
-      }
-
-      case Token::TOKEN_ARRAY_BEGIN:
-      {
-         Array& array = element;
-         Parse(array, tokenStream);
-         break;
-      }
-
-      case Token::TOKEN_STRING:
-      {
-         String& string = element;
-         Parse(string, tokenStream);
-         break;
-      }
-
-      case Token::TOKEN_NUMBER:
-      {
-         Number& number = element;
-         Parse(number, tokenStream);
-         break;
-      }
-
-      case Token::TOKEN_BOOLEAN:
-      {
-         Boolean& boolean = element;
-         Parse(boolean, tokenStream);
-         break;
-      }
-
-      case Token::TOKEN_NULL:
-      {
-         Null& null = element;
-         Parse(null, tokenStream);
-         break;
-      }
-
       default:
-      {
          throw ParseException("Unexpected token: " + token.sValue, token.locBegin, token.locEnd);
    }
-   }
 }
 
-
+Object Reader::ParseObject(Reader::TokenStream& tokenStream)
-void Reader::Parse(Object& object, Reader::TokenStream& tokenStream)
 {
    MatchExpectedToken(Token::TOKEN_OBJECT_BEGIN, tokenStream);
 
-   bool bContinue = (tokenStream.EOS() == false &&
+   Object object;
-                     tokenStream.Peek().nType != Token::TOKEN_OBJECT_END);
+
-   while (bContinue)
+   while (!tokenStream.EOS() && tokenStream.Peek().nType != Token::TOKEN_OBJECT_END)
    {
       // first the member name. save the token in case we have to throw an exception
       const Token& tokenName = tokenStream.Peek();
       std::string const& name = MatchExpectedToken(Token::TOKEN_STRING, tokenStream);
 
       if (object.count(name))
-      {
          throw ParseException("Duplicate object member token: " + name, tokenName.locBegin, tokenName.locEnd);
-      }
 
       // ...then the key/value separator...
       MatchExpectedToken(Token::TOKEN_MEMBER_ASSIGN, tokenStream);
 
       // ...then the value itself (can be anything).
-      UnknownElement value;
+     object[name] = Parse(tokenStream);
-      Parse(value, tokenStream);
 
-     object[name] = value;
+      if (!tokenStream.EOS() && tokenStream.Peek().nType != Token::TOKEN_OBJECT_END)
-
-      bContinue = (tokenStream.EOS() == false &&
-                   tokenStream.Peek().nType == Token::TOKEN_NEXT_ELEMENT);
-      if (bContinue)
          MatchExpectedToken(Token::TOKEN_NEXT_ELEMENT, tokenStream);
    }
 
    MatchExpectedToken(Token::TOKEN_OBJECT_END, tokenStream);
+
+   return object;
 }
 
-
+Array Reader::ParseArray(Reader::TokenStream& tokenStream)
-void Reader::Parse(Array& array, Reader::TokenStream& tokenStream)
 {
    MatchExpectedToken(Token::TOKEN_ARRAY_BEGIN, tokenStream);
 
-   bool bContinue = (tokenStream.EOS() == false &&
+   Array array;
-                     tokenStream.Peek().nType != Token::TOKEN_ARRAY_END);
-   while (bContinue)
-   {
-      // ...what's next? could be anything
-      array.push_back(UnknownElement());
-      UnknownElement& element = array.back();
-      Parse(element, tokenStream);
 
-      bContinue = (tokenStream.EOS() == false &&
+   while (!tokenStream.EOS() && tokenStream.Peek().nType != Token::TOKEN_ARRAY_END)
-                   tokenStream.Peek().nType == Token::TOKEN_NEXT_ELEMENT);
+   {
-      if (bContinue)
+      array.push_back(Parse(tokenStream));
+
+      if (!tokenStream.EOS() && tokenStream.Peek().nType != Token::TOKEN_ARRAY_END)
          MatchExpectedToken(Token::TOKEN_NEXT_ELEMENT, tokenStream);
    }
 
    MatchExpectedToken(Token::TOKEN_ARRAY_END, tokenStream);
+
+   return array;
 }
 
-
+String Reader::ParseString(Reader::TokenStream& tokenStream)
-void Reader::Parse(String& string, Reader::TokenStream& tokenStream)
 {
-   string = MatchExpectedToken(Token::TOKEN_STRING, tokenStream);
+   return MatchExpectedToken(Token::TOKEN_STRING, tokenStream);
 }
 
-
+Number Reader::ParseNumber(Reader::TokenStream& tokenStream)
-void Reader::Parse(Number& number, Reader::TokenStream& tokenStream)
 {
    const Token& currentToken = tokenStream.Peek(); // might need this later for throwing exception
    const std::string& sValue = MatchExpectedToken(Token::TOKEN_NUMBER, tokenStream);
@@ -438,25 +386,21 @@ void Reader::Parse(Number& number, Reader::TokenStream& tokenStream)
    iStr >> dValue;
 
    // did we consume all characters in the token?
-   if (iStr.eof() == false)
+   if (!iStr.eof())
-   {
       throw ParseException("Unexpected character in NUMBER token: " + iStr.peek(), currentToken.locBegin, currentToken.locEnd);
-   }
 
-   number = dValue;
+   return dValue;
 }
 
-
+Boolean Reader::ParseBoolean(Reader::TokenStream& tokenStream)
-void Reader::Parse(Boolean& boolean, Reader::TokenStream& tokenStream)
 {
-   const std::string& sValue = MatchExpectedToken(Token::TOKEN_BOOLEAN, tokenStream);
+   return MatchExpectedToken(Token::TOKEN_BOOLEAN, tokenStream) == "true";
-   boolean = (sValue == "true");
 }
 
-
+Null Reader::ParseNull(Reader::TokenStream& tokenStream)
-void Reader::Parse(Null&, Reader::TokenStream& tokenStream)
 {
    MatchExpectedToken(Token::TOKEN_NULL, tokenStream);
+   return Null();
 }
 
 

aegisub/libaegisub/common/hotkey.cpp

@@ -69,7 +69,7 @@ Hotkey::Hotkey(const std::string &file, const std::string &default_config)
 	LOG_D("hotkey/init") << "Generating hotkeys.";
 
 	json::UnknownElement hotkey_root = agi::json_util::file(config_file, default_config);
-	json::Object object = hotkey_root;
+	json::Object const& object = hotkey_root;
 
 	for (json::Object::const_iterator index(object.begin()); index != object.end(); ++index)
 		BuildHotkey(index->first, index->second);

aegisub/libaegisub/common/log.cpp

@@ -93,6 +93,8 @@ LogSink::~LogSink() {
 		array.push_back(entry);
 	}
 
+	root["timeval"] = json::Object();
+
 	json::Array timeval_open;
 	timeval_open.push_back(time_start.tv_sec);
 	timeval_open.push_back(time_start.tv_usec);

aegisub/libaegisub/include/libaegisub/cajun/elements.h

@@ -79,24 +79,24 @@ public:
    UnknownElement& operator = (const UnknownElement& unknown);
 
    // implicit cast to actual element type. throws on failure
-   operator const Object& () const;
+   operator Object const&() const;
-   operator const Array& () const;
+   operator Array const&() const;
-   operator const Number& () const;
+   operator Number const&() const;
-   operator const Boolean& () const;
+   operator Boolean const&() const;
-   operator const String& () const;
+   operator String const&() const;
-   operator const Null& () const;
+   operator Null const&() const;
-
+   operator Object&();
-   // implicit cast to actual element type. *converts* on failure, and always returns success
+   operator Array&();
-   operator Object& ();
+   operator Number&();
-   operator Array& ();
+   operator Boolean&();
-   operator Number& ();
+   operator String&();
-   operator Boolean& ();
+   operator Null&();
-   operator String& ();
-   operator Null& ();
 
    // provides quick access to children when real element type is object
-   UnknownElement& operator[] (const char *key) { return operator[](std::string(key)); }
+   template<int N>
-   const UnknownElement& operator[] (const char *key) const { return operator[](std::string(key)); }
+   UnknownElement& operator[] (const char (&key)[N]) { return operator[](std::string(key)); }
+   template<int N>
+   const UnknownElement& operator[] (const char (&key)[N]) const { return operator[](std::string(key)); }
    UnknownElement& operator[] (const std::string& key);
    const UnknownElement& operator[] (const std::string& key) const;
 
@@ -109,7 +109,8 @@ public:
    void Accept(Visitor& visitor);
 
    // tests equality. first checks type, then value if possible
-   bool operator == (const UnknownElement& element) const;
+   bool operator ==(const UnknownElement& element) const;
+   bool operator !=(const UnknownElement& element) const { return !(*this == element); }
 
 private:
    class Imp;
@@ -118,10 +119,10 @@ private:
    class Imp_T;
 
    template <typename ElementTypeT>
-   const ElementTypeT& CastTo() const;
+   ElementTypeT const& CastTo() const;
 
    template <typename ElementTypeT>
-   ElementTypeT& ConvertTo();
+   ElementTypeT& CastTo();
 
    Imp* m_pImp;
 };

aegisub/libaegisub/include/libaegisub/cajun/reader.h

@@ -110,13 +110,13 @@ private:
    void MatchExpectedString(const std::string& sExpected, InputStream& inputStream);
 
    // parsing token sequence into element structure
-   void Parse(UnknownElement& element, TokenStream& tokenStream);
+   UnknownElement Parse(TokenStream& tokenStream);
-   void Parse(Object& object, TokenStream& tokenStream);
+   Object ParseObject(TokenStream& tokenStream);
-   void Parse(Array& array, TokenStream& tokenStream);
+   Array ParseArray(TokenStream& tokenStream);
-   void Parse(String& string, TokenStream& tokenStream);
+   String ParseString(TokenStream& tokenStream);
-   void Parse(Number& number, TokenStream& tokenStream);
+   Number ParseNumber(TokenStream& tokenStream);
-   void Parse(Boolean& boolean, TokenStream& tokenStream);
+   Boolean ParseBoolean(TokenStream& tokenStream);
-   void Parse(Null& null, TokenStream& tokenStream);
+   Null ParseNull(TokenStream& tokenStream);
 
    const std::string& MatchExpectedToken(Token::Type nExpected, TokenStream& tokenStream);
 };