Add StreamWriter for non-buffered JSON file writing.

Jzon.cpp

@@ -598,6 +598,168 @@ namespace Jzon
 	}
 
 
+	StreamWriter::StreamWriter(std::ostream & stream, const Format & format)
+		: stream(stream), first(true)
+	{
+		this->format = format;
+		indentationChar = (format.useTabs ? '\t' : ' ');
+		spacing = (format.spacing ? " " : "");
+		newline = (format.newline ? "\n" : spacing);
+	}
+	StreamWriter::~StreamWriter()
+	{
+	}
+	void StreamWriter::startObject()
+	{
+		if (!isComplete() && streamStack.back() == StreamState::SS_OBJECT)
+			throw "Object members must be properties";
+		if (isComplete() && !first)
+			throw "Root JSON is complete";
+		if (!first) stream << "," << newline;
+		stream << getIndentation(streamStack.size()) << "{" << newline;
+		streamStack.push_back(StreamState::SS_OBJECT);
+		first = true;
+	}
+	void StreamWriter::startObject(const std::string & name)
+	{
+		if (!isComplete() && streamStack.back() != StreamState::SS_OBJECT)
+			throw "Cannot create property outside of an object";
+		if (isComplete() && !first)
+			throw "Root JSON is complete";
+		if (!first) stream << "," << newline;
+		stream << getIndentation(streamStack.size()) << "\"" << name << "\":" << spacing << "{" << newline;
+		streamStack.push_back(StreamState::SS_OBJECT);
+		first = true;
+	}
+	void StreamWriter::endObject()
+	{
+		if (streamStack.back() != StreamState::SS_OBJECT)
+			throw "Cannot end object while not in object";
+		streamStack.pop_back();
+		stream << newline << getIndentation(streamStack.size()) << "}";
+		first = false;
+	}
+	void StreamWriter::startArray()
+	{
+		if (!isComplete() && streamStack.back() == StreamState::SS_OBJECT)
+			throw "Object members must be properties";
+		if (isComplete() && !first)
+			throw "Root JSON is complete";
+		if (!first) stream << "," << newline;
+		stream << getIndentation(streamStack.size()) << "[" << newline;
+		streamStack.push_back(StreamState::SS_ARRAY);
+		first = true;
+	}
+	void StreamWriter::startArray(const std::string & name)
+	{
+		if (!isComplete() && streamStack.back() != StreamState::SS_OBJECT)
+			throw "Cannot create property outside of an object";
+		if (isComplete() && !first)
+			throw "Root JSON is complete";
+		if (!first) stream << "," << newline;
+		stream << getIndentation(streamStack.size()) << "\"" << name << "\":" << spacing << "[" << newline;
+		streamStack.push_back(StreamState::SS_ARRAY);
+		first = true;
+	}
+	void StreamWriter::endArray()
+	{
+		if (streamStack.back() != StreamState::SS_ARRAY)
+			throw "Cannot end array while not in array";
+		streamStack.pop_back();
+		stream << newline << getIndentation(streamStack.size()) << "]";
+		first = false;
+	}
+	void StreamWriter::addNode(const Node & node)
+	{
+		if (!isComplete() && streamStack.back() == StreamState::SS_OBJECT)
+			throw "Object members must be properties";
+		if (isComplete() && !first)
+			throw "Root JSON is complete";
+		if (!first) stream << "," << newline;
+		stream << getIndentation(streamStack.size());
+		writeNode(node, streamStack.size());
+		first = false;
+	}
+	void StreamWriter::addNode(const std::string & name, const Node & node)
+	{
+		if (!isComplete() && streamStack.back() != StreamState::SS_OBJECT)
+			throw "Cannot create property outside of an object";
+		if (isComplete() && !first)
+			throw "Root JSON is complete";
+		if (!first) stream << "," << newline;
+		stream << getIndentation(streamStack.size()) << "\"" << name << "\":" << spacing;
+		writeNode(node, streamStack.size());
+		first = false;
+	}
+	bool StreamWriter::isComplete()
+	{
+		return streamStack.size() == 0;
+	}
+	std::string StreamWriter::getIndentation(unsigned int level) const
+	{
+		if (!format.newline) return "";
+		else return std::string(format.indentSize * level, indentationChar);
+	}
+	void StreamWriter::writeNode(const Node& node, unsigned int level) const
+	{
+		switch (node.getType())
+		{
+			case Node::T_INVALID: break;
+			case Node::T_OBJECT: writeObject(node, level); break;
+			case Node::T_ARRAY: writeArray(node, level); break;
+			case Node::T_NULL: // Fallthrough
+			case Node::T_STRING: // Fallthrough
+			case Node::T_NUMBER: // Fallthrough
+			case Node::T_BOOL: writeValue(node); break;
+		}
+	}
+	void StreamWriter::writeObject(const Node& node, unsigned int level) const
+	{
+		stream << "{" << newline;
+
+		for (Node::const_iterator it = node.begin(); it != node.end(); ++it)
+		{
+			const std::string& name = (*it).first;
+			const Node& value = (*it).second;
+
+			if (it != node.begin())
+				stream << "," << newline;
+			stream << getIndentation(level + 1) << "\"" << name << "\"" << ":" << spacing;
+			writeNode(value, level + 1);
+		}
+
+		stream << newline << getIndentation(level) << "}";
+	}
+	void StreamWriter::writeArray(const Node& node, unsigned int level) const
+	{
+		stream << "[" << newline;
+
+		for (Node::const_iterator it = node.begin(); it != node.end(); ++it)
+		{
+			const Node& value = (*it).second;
+
+			if (it != node.begin())
+				stream << "," << newline;
+			stream << getIndentation(level + 1);
+			writeNode(value, level + 1);
+		}
+
+		stream << newline << getIndentation(level) << "]";
+	}
+	void StreamWriter::writeValue(const Node& node) const
+	{
+		if (node.isString())
+		{
+			stream << "\"" << escapeString(node.toString()) << "\"";
+		}
+		else
+		{
+			stream << node.toString();
+		}
+	}
+
+
+
 	Parser::Parser()
 	{
 	}

Jzon.h

@@ -66,7 +66,7 @@ namespace Jzon
 		class iterator : public std::iterator<std::input_iterator_tag, NamedNode>
 		{
 		public:
-            iterator() : p(0) {}
+			iterator() : p(0) {}
 			iterator(NamedNode *o) : p(o) {}
 			iterator(const iterator &it) : p(it.p) {}
 
@@ -254,6 +254,45 @@ namespace Jzon
 		const char *spacing;
 	};
 
+	class JZON_API StreamWriter
+	{
+	public:
+		explicit StreamWriter(std::ostream& stream, const Format& format = NoFormat);
+		~StreamWriter();
+
+		void startObject();
+		void startObject(const std::string& name);
+		void endObject();
+		void startArray();
+		void startArray(const std::string& name);
+		void endArray();
+		void addNode(const Node& node);
+		void addNode(const std::string& name, const Node& node);
+
+		bool isComplete();
+
+	private:
+		enum StreamState
+		{
+			SS_OBJECT,
+			SS_ARRAY,
+		};
+		std::string getIndentation(unsigned int level) const;
+		void writeNode(const Node& node, unsigned int level) const;
+		void writeObject(const Node& node, unsigned int level) const;
+		void writeArray(const Node& node, unsigned int level) const;
+		void writeValue(const Node& node) const;
+
+		Format format;
+		char indentationChar;
+		const char* newline;
+		const char* spacing;
+
+		std::ostream& stream;
+		bool first;
+		std::vector<StreamState> streamStack;
+	};
+
 	class JZON_API Parser
 	{
 	public:

README.md

@@ -33,9 +33,40 @@ node.add("bool", true);
 }
 
 Jzon::Writer writer;
+writer.setFormat(Jzon::StandardFormat);
 writer.writeStream(node, cout);
 ```
 
+```c
+Jzon::StreamWriter writer = Jzon::StreamWriter(std::cout, Jzon::StandardFormat);
+writer.startObject();
+{
+    writer.addNode("name", "value");
+    writer.addNode("number", 20);
+    writer.addNode("anothernumber", 15.3);
+    writer.addNode("bool", true);
+    writer.startArray("array");
+    {
+        writer.addNode(1);
+        writer.addNode("asdf");
+        writer.startObject();
+        {
+            writer.addNode("key1", "val1");
+            writer.addNode("key2", "val2");
+        }
+        writer.endObject();
+    }
+    writer.endArray();
+    writer.startObject("subnode");
+    {
+        writer.addNode("key1", "val1");
+        writer.addNode("key2", "val2");
+    }
+    writer.endObject();
+}
+writer.endObject();
+```
+
 #### Result
 ```json
 {