Add toJSONString to JSONTreeNode

Sources/Document/Json/JSONTree.swift

@@ -18,6 +18,7 @@ import Foundation
 
 public protocol JSONTreeNode: Equatable {
     var type: TreeNodeType { get }
+    var toJSONString: String { get }
 }
 
 struct TreeChangeWithPath {
@@ -86,6 +87,39 @@ public struct JSONTreeElementNode: JSONTreeNode {
         self.attributes = attributes
         self.children = children
     }
+
+    public var toJSONString: String {
+        var childrenString = ""
+        if self.children.isEmpty == false {
+            childrenString = self.children.compactMap { $0.toJSONString }.joined(separator: ",")
+        }
+
+        var resultString = "{\"type\":\"\(self.type)\",\"children\":[\(childrenString)]"
+
+        if self.attributes.isEmpty == false {
+            let sortedKeys = self.attributes.keys.sorted()
+
+            let attrsString = sortedKeys.compactMap { key in
+                if let value = attributes[key] as? Int {
+                    return "\"\(key)\":\(value)"
+                } else if let value = attributes[key] as? Double {
+                    return "\"\(key)\":\(value)"
+                } else if let value = attributes[key] as? Bool {
+                    return "\"\(key)\":\(value)"
+                } else if let value = attributes[key] as? String {
+                    return "\"\(key)\":\"\(value)\""
+                } else {
+                    return "\"\(key)\":null"
+                }
+            }.joined(separator: ",")
+
+            resultString += ",\"attributes\":{\(attrsString)}"
+        }
+
+        resultString += "}"
+
+        return resultString
+    }
 }
 
 /**
@@ -98,6 +132,10 @@ public struct JSONTreeTextNode: JSONTreeNode {
     public init(value: String) {
         self.value = value
     }
+
+    public var toJSONString: String {
+        return "{\"type\":\"\(self.type)\",\"value\":\"\(self.value)\"}"
+    }
 }
 
 /**

Tests/Unit/Document/JONSTreeTests.swift

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2023 The Yorkie Authors. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import XCTest
+@testable import Yorkie
+
+final class JONSTreeTests: XCTestCase {
+    func test_json_string() throws {
+        let textNode = JSONTreeTextNode(value: "X")
+
+        XCTAssertEqual(textNode.toJSONString, "{\"type\":\"text\",\"value\":\"X\"}")
+
+        let elementNode = JSONTreeElementNode(type: "doc",
+                                              attributes: [
+                                                  "intValue": 100,
+                                                  "doubleValue": 10.5,
+                                                  "boolean": true,
+                                                  "string": "testString"
+                                              ],
+                                              children: [
+                                                  JSONTreeElementNode(type: "p"),
+                                                  JSONTreeTextNode(value: "Y")
+                                              ])
+
+        XCTAssertEqual(elementNode.toJSONString, "{\"type\":\"doc\",\"children\":[{\"type\":\"p\",\"children\":[]},{\"type\":\"text\",\"value\":\"Y\"}],\"attributes\":{\"boolean\":true,\"doubleValue\":10.5,\"intValue\":100,\"string\":\"testString\"}}")
+    }
+}