json: Allow formatting read json back to writer.

ext/native/json/json_writer.cpp

@@ -1,5 +1,6 @@
 #include <iomanip>
 #include <cstring>
+#include "ext/vjson/json.h"
 #include "json/json_writer.h"
 
 JsonWriter::JsonWriter(int flags) {
@@ -15,6 +16,16 @@ void JsonWriter::begin() {
 	stack_.push_back(StackEntry(DICT));
 }
 
+void JsonWriter::beginArray() {
+	str_ << "[";
+	stack_.push_back(StackEntry(ARRAY));
+}
+
+void JsonWriter::beginRaw() {
+	// For the uncommon case of writing a value directly, to avoid duplicated code.
+	stack_.push_back(StackEntry(RAW));
+}
+
 void JsonWriter::end() {
 	pop();
 	if (pretty_)
@@ -41,6 +52,8 @@ const char *JsonWriter::indent() const {
 }
 
 const char *JsonWriter::arrayIndent() const {
+	if (!pretty_)
+		return "";
 	int amount = (int)stack_.size() + 1;
 	amount *= 2;	// 2-space indent.
 	return stack_.back().first ? indent(amount) : "";
@@ -128,6 +141,19 @@ void JsonWriter::writeString(const char *name, const char *value) {
 	stack_.back().first = false;
 }
 
+void JsonWriter::writeRaw(const char *value) {
+	str_ << arrayComma() << arrayIndent() << value;
+	stack_.back().first = false;
+}
+
+void JsonWriter::writeRaw(const char *name, const char *value) {
+	str_ << comma() << indent() << "\"";
+	writeEscapedString(name);
+	str_ << (pretty_ ? "\": " : "\":");
+	str_ << value;
+	stack_.back().first = false;
+}
+
 void JsonWriter::pop() {
 	BlockType type = stack_.back().type;
 	stack_.pop_back();
@@ -140,6 +166,8 @@ void JsonWriter::pop() {
 	case DICT:
 		str_ << "}";
 		break;
+	case RAW:
+		break;
 	}
 	if (stack_.size() > 0)
 		stack_.back().first = false;
@@ -181,3 +209,109 @@ void JsonWriter::writeEscapedString(const char *str) {
 		str_ << str;
 	}
 }
+
+static void json_stringify_object(JsonWriter &writer, const json_value *value);
+static void json_stringify_array(JsonWriter &writer, const json_value *value);
+
+std::string json_stringify(const json_value *value) {
+	JsonWriter writer;
+
+	// Handle direct values too, not just objects.
+	switch (value->type) {
+	case JSON_NULL:
+	case JSON_STRING:
+	case JSON_INT:
+	case JSON_FLOAT:
+	case JSON_BOOL:
+		writer.beginRaw();
+		// It's the same as a one entry array without brackets, so reuse.
+		json_stringify_array(writer, value);
+		break;
+
+	case JSON_OBJECT:
+		writer.begin();
+		for (const json_value *it = value->first_child; it; it = it->next_sibling) {
+			json_stringify_object(writer, it);
+		}
+		break;
+	case JSON_ARRAY:
+		writer.beginArray();
+		for (const json_value *it = value->first_child; it; it = it->next_sibling) {
+			json_stringify_array(writer, it);
+		}
+		break;
+	}
+
+	writer.end();
+	return writer.str();
+}
+
+static void json_stringify_object(JsonWriter &writer, const json_value *value) {
+	switch (value->type) {
+	case JSON_NULL:
+		writer.writeRaw(value->name, "null");
+		break;
+	case JSON_STRING:
+		writer.writeString(value->name, value->string_value);
+		break;
+	case JSON_INT:
+		writer.writeInt(value->name, value->int_value);
+		break;
+	case JSON_FLOAT:
+		writer.writeFloat(value->name, value->float_value);
+		break;
+	case JSON_BOOL:
+		writer.writeBool(value->name, value->int_value != 0);
+		break;
+
+	case JSON_OBJECT:
+		writer.pushDict(value->name);
+		for (const json_value *it = value->first_child; it; it = it->next_sibling) {
+			json_stringify_object(writer, it);
+		}
+		writer.pop();
+		break;
+	case JSON_ARRAY:
+		writer.pushArray(value->name);
+		for (const json_value *it = value->first_child; it; it = it->next_sibling) {
+			json_stringify_array(writer, it);
+		}
+		writer.pop();
+		break;
+	}
+}
+
+static void json_stringify_array(JsonWriter &writer, const json_value *value) {
+	switch (value->type) {
+	case JSON_NULL:
+		writer.writeRaw("null");
+		break;
+	case JSON_STRING:
+		writer.writeString(value->string_value);
+		break;
+	case JSON_INT:
+		writer.writeInt(value->int_value);
+		break;
+	case JSON_FLOAT:
+		writer.writeFloat(value->float_value);
+		break;
+	case JSON_BOOL:
+		writer.writeBool(value->int_value != 0);
+		break;
+
+	case JSON_OBJECT:
+		writer.begin();
+		for (const json_value *it = value->first_child; it; it = it->next_sibling) {
+			json_stringify_object(writer, it);
+		}
+		writer.pop();
+		break;
+	case JSON_ARRAY:
+		writer.beginArray();
+		for (const json_value *it = value->first_child; it; it = it->next_sibling) {
+			json_stringify_array(writer, it);
+		}
+		writer.pop();
+		break;
+	}
+}

ext/native/json/json_writer.h

@@ -7,8 +7,7 @@
 //
 // Does not deal with encodings in any way.
 //
-// Zero dependencies apart from stdlib.
-// See json_writer_test.cpp for usage.
+// Zero dependencies apart from stdlib (if you remove the vhjson usage.)
 
 #include <string>
 #include <vector>
@@ -19,6 +18,8 @@ public:
 	JsonWriter(int flags = NORMAL);
 	~JsonWriter();
 	void begin();
+	void beginArray();
+	void beginRaw();
 	void end();
 	void pushDict(const char *name);
 	void pushArray(const char *name);
@@ -40,6 +41,17 @@ public:
 	void writeString(const std::string &name, const std::string &value) {
 		writeString(name.c_str(), value.c_str());
 	}
+	void writeRaw(const char *value);
+	void writeRaw(const char *name, const char *value);
+	void writeRaw(const std::string &value) {
+		writeRaw(value.c_str());
+	}
+	void writeRaw(const char *name, const std::string &value) {
+		writeRaw(name, value.c_str());
+	}
+	void writeRaw(const std::string &name, const std::string &value) {
+		writeRaw(name.c_str(), value.c_str());
+	}
 
 	std::string str() const {
 		return str_.str();
@@ -61,6 +73,7 @@ private:
 	enum BlockType {
 		ARRAY,
 		DICT,
+		RAW,
 	};
 	struct StackEntry {
 		StackEntry(BlockType t) : type(t), first(true) {}
@@ -71,3 +84,6 @@ private:
 	std::ostringstream str_;
 	bool pretty_;
 };
+
+struct json_value;
+std::string json_stringify(const json_value *json);