Add JSON parser/generator.

2 files changed, 163 insertions, 0 deletions

diff --git a/json.cpp b/json.cpp
new file mode 100644
index 0000000..0277cce
--- /dev/null
+++ b/json.cpp
@@ -0,0 +1,131 @@
+#include "json.h"
+
+#include <boost/spirit/include/qi.hpp>
+#include <boost/spirit/include/phoenix_operator.hpp>
+#include <boost/fusion/include/std_pair.hpp>
+
+namespace qi = boost::spirit::qi;
+
+using namespace JSON;
+
+bool JSON::parse(const std::string& s, Value& v) {
+	typedef std::string::const_iterator Iterator;
+	
+	qi::rule<Iterator, bool()> bool_p = qi::lit("false")[qi::_val = false] | qi::lit("true")[qi::_val = true];
+	
+	qi::rule<Iterator, boost::variant<int, float>()> number_p = (qi::int_ >> !(qi::lit('.') | 'e' | 'E')) | qi::float_;
+	
+	qi::rule<Iterator, char()> char_p = (qi::char_ - '\"' - '\\') | '\\' >> (
+		qi::char_('\"') |
+		qi::char_('\\') |
+		qi::char_('/') |
+		'b' >> qi::attr('\b') |
+		'f' >> qi::attr('\f') |
+		'n' >> qi::attr('\n') |
+		'r' >> qi::attr('\r') |
+		't' >> qi::attr('\t')
+	);
+	
+	qi::rule<Iterator, std::string()> string_p = '\"' >> *(char_p) >> '\"';
+	
+	qi::rule<Iterator, Value()> value_p;
+	
+	qi::rule<Iterator, Array()> array_p = '[' >> -(value_p % ',') >> ']';
+	
+	qi::rule<Iterator, std::pair<std::string, Value>()> key_value_p = string_p >> ":" >> value_p;
+	qi::rule<Iterator, Object()> object_p = '{' >> -(key_value_p % ',') >> '}';
+	
+	value_p = qi::omit[*qi::space] >> (bool_p | number_p | string_p | array_p | object_p) >> qi::omit[*qi::space];
+	
+	return qi::parse(s.begin(), s.end(), value_p, v);
+}
+
+struct generate : public boost::static_visitor<std::ostream&> {
+	std::ostream& stream;
+	generate(std::ostream& s) : stream(s) {}
+	
+	std::ostream& operator()(const bool& x) const {
+		return stream << (x ? "true" : "false");
+	}
+	
+	std::ostream& operator()(const int& x) const {
+		return stream << x;
+	}
+	
+	std::ostream& operator()(const float& x) const {
+		return stream << x;
+	}
+	
+	std::ostream& operator()(const std::string& x) const {
+		stream << '\"';
+		for(std::string::const_iterator it = x.begin(); it != x.end(); it++) {
+			switch(*it) {
+				case '\"':
+				case '\\':
+				case '/':
+					stream << '\\' << *it;
+					break;
+				
+				case '\b':
+					stream << "\\b";
+					break;
+				
+				case '\f':
+					stream << "\\f";
+					break;
+				
+				case '\n':
+					stream << "\\n";
+					break;
+				
+				case '\r':
+					stream << "\\r";
+					break;
+				
+				case '\t':
+					stream << "\\t";
+					break;
+				
+				default:
+					stream << *it;
+			}
+		}
+		return stream << '\"';
+	}
+	
+	std::ostream& operator()(const Array& x) const {
+		stream << "[";
+		for(Array::const_iterator it = x.begin();;) {
+			boost::apply_visitor(generate(stream), *it);
+			
+			if(++it == x.end()) {
+				break;
+			}
+			
+			stream << ", ";
+		}
+		return stream << "]";
+	}
+	
+	std::ostream& operator()(const Object& x) const {
+		stream << "{";
+		for(Object::const_iterator it = x.begin();;) {
+			(*this)(it->first);
+			
+			stream << ": ";
+			
+			boost::apply_visitor(generate(stream), it->second);
+			
+			if(++it == x.end()) {
+				break;
+			}
+			
+			stream << ", ";
+		}
+		return stream << "}";
+	}
+};
+
+std::ostream& operator<<(std::ostream& s, const Value& v) {
+	return boost::apply_visitor(generate(s), v);
+}
diff --git a/json.h b/json.h
new file mode 100644
index 0000000..0e18911
--- /dev/null
+++ b/json.h
@@ -0,0 +1,32 @@
+#ifndef JSON_H
+#define JSON_H
+
+#include <string>
+#include <vector>
+#include <map>
+#include <iostream>
+
+#include <boost/variant.hpp>
+
+namespace JSON {
+	// TODO: Support null.
+	typedef boost::make_recursive_variant<
+		bool,
+		int,
+		float,
+		std::string,
+		std::vector<boost::recursive_variant_ >,
+		std::map<std::string, boost::recursive_variant_ >
+	>::type Value;
+	
+	typedef std::vector<Value> Array;
+	typedef std::map<std::string, Value> Object;
+	
+	//! Parse JSON string into value-tree.
+	bool parse(const std::string& s, Value& v);
+};
+
+//! Write JSON to stream.
+std::ostream& operator<<(std::ostream& s, const JSON::Value& v);
+
+#endif