[json-node] Add copy() and unmodifible() for deep copy options (#302)

Ability to create a mutable deep copy and an immutable deep copy

Author: rbygrave

json-node/src/main/java/io/avaje/json/node/JsonArray.java

@@ -37,6 +37,24 @@ public String toString() {
     return text();
   }
 
+  @Override
+  public JsonArray unmodifiable() {
+    final var newList = new ArrayList<JsonNode>(children.size());
+    for (JsonNode child : children) {
+      newList.add(child.unmodifiable());
+    }
+    return of(newList);
+  }
+
+  @Override
+  public JsonArray copy() {
+    final var newList = new ArrayList<JsonNode>(children.size());
+    for (JsonNode child : children) {
+      newList.add(child.copy());
+    }
+    return new JsonArray(newList);
+  }
+
   @Override
   public Type type() {
     return Type.ARRAY;

json-node/src/main/java/io/avaje/json/node/JsonBoolean.java

@@ -1,6 +1,6 @@
 package io.avaje.json.node;
 
-public final class JsonBoolean implements JsonNode {
+public final /*value*/ class JsonBoolean implements JsonNode {
 
   private final boolean value;
 
@@ -17,6 +17,16 @@ public String toString() {
     return text();
   }
 
+  @Override
+  public JsonBoolean unmodifiable() {
+    return this;
+  }
+
+  @Override
+  public JsonBoolean copy() {
+    return this;
+  }
+
   @Override
   public Type type() {
     return Type.BOOLEAN;

json-node/src/main/java/io/avaje/json/node/JsonDecimal.java

@@ -4,7 +4,7 @@
 
 import java.math.BigDecimal;
 
-public final class JsonDecimal implements JsonNumber {
+public final /*value*/ class JsonDecimal implements JsonNumber {
 
   private final BigDecimal value;
 
@@ -21,6 +21,16 @@ public String toString() {
     return text();
   }
 
+  @Override
+  public JsonDecimal unmodifiable() {
+    return this;
+  }
+
+  @Override
+  public JsonDecimal copy() {
+    return this;
+  }
+
   @Override
   public Type type() {
     return Type.NUMBER;

json-node/src/main/java/io/avaje/json/node/JsonDouble.java

@@ -4,7 +4,7 @@
 
 import java.math.BigDecimal;
 
-public final class JsonDouble implements JsonNumber {
+public final /*value*/ class JsonDouble implements JsonNumber {
 
   private final double value;
 
@@ -21,6 +21,16 @@ public String toString() {
     return text();
   }
 
+  @Override
+  public JsonDouble unmodifiable() {
+    return this;
+  }
+
+  @Override
+  public JsonDouble copy() {
+    return this;
+  }
+
   @Override
   public Type type() {
     return Type.NUMBER;

json-node/src/main/java/io/avaje/json/node/JsonInteger.java

@@ -4,7 +4,7 @@
 
 import java.math.BigDecimal;
 
-public final class JsonInteger implements JsonNumber {
+public final /*value*/ class JsonInteger implements JsonNumber {
 
   private final int value;
 
@@ -21,6 +21,16 @@ public String toString() {
     return text();
   }
 
+  @Override
+  public JsonInteger unmodifiable() {
+    return this;
+  }
+
+  @Override
+  public JsonInteger copy() {
+    return this;
+  }
+
   @Override
   public Type type() {
     return Type.NUMBER;

json-node/src/main/java/io/avaje/json/node/JsonLong.java

@@ -4,7 +4,7 @@
 
 import java.math.BigDecimal;
 
-public final class JsonLong implements JsonNumber {
+public final /*value*/ class JsonLong implements JsonNumber {
 
   private final long value;
 
@@ -21,6 +21,16 @@ public String toString() {
     return text();
   }
 
+  @Override
+  public JsonLong unmodifiable() {
+    return this;
+  }
+
+  @Override
+  public JsonLong copy() {
+    return this;
+  }
+
   @Override
   public Type type() {
     return Type.NUMBER;

json-node/src/main/java/io/avaje/json/node/JsonNode.java

@@ -72,6 +72,16 @@ public boolean isObject() {
    */
   String text();
 
+  /**
+   * Return an unmodifiable deep copy of the JsonNode.
+   */
+  JsonNode unmodifiable();
+
+  /**
+   * Return a mutable deep copy of the JsonNode.
+   */
+  JsonNode copy();
+
   /**
    * Find a node given a path using dot notation.
    * @param path The path in dot notation

json-node/src/main/java/io/avaje/json/node/JsonObject.java

@@ -51,6 +51,24 @@ public String text() {
     return children.toString();
   }
 
+  @Override
+  public JsonObject unmodifiable() {
+    final var mapCopy = new LinkedHashMap<String,JsonNode>();
+    for (Map.Entry<String, JsonNode> entry : children.entrySet()) {
+      mapCopy.put(entry.getKey(), entry.getValue().unmodifiable());
+    }
+    return JsonObject.of(mapCopy);
+  }
+
+  @Override
+  public JsonObject copy() {
+    final var mapCopy = new LinkedHashMap<String,JsonNode>();
+    for (Map.Entry<String, JsonNode> entry : children.entrySet()) {
+      mapCopy.put(entry.getKey(), entry.getValue().copy());
+    }
+    return new JsonObject(mapCopy);
+  }
+
   /**
    * Return true if the json object contains no elements.
    */

json-node/src/main/java/io/avaje/json/node/JsonString.java

@@ -1,6 +1,6 @@
 package io.avaje.json.node;
 
-public final class JsonString implements JsonNode {
+public final /*value*/ class JsonString implements JsonNode {
 
   private final String value;
 
@@ -17,6 +17,16 @@ public String toString() {
     return text();
   }
 
+  @Override
+  public JsonString unmodifiable() {
+    return this;
+  }
+
+  @Override
+  public JsonString copy() {
+    return this;
+  }
+
   @Override
   public Type type() {
     return Type.STRING;

json-node/src/test/java/io/avaje/json/node/JsonArrayTest.java

@@ -6,6 +6,7 @@
 import java.util.stream.Collectors;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
 class JsonArrayTest {
 
@@ -87,4 +88,31 @@ void add() {
     assertThat(elements.get(4)).isInstanceOf(JsonObject.class);
   }
 
+  @Test
+  void copy() {
+    final JsonArray source = JsonArray.create()
+            .add("foo")
+            .add(JsonObject.create().add("b", 42));
+
+    JsonArray copy = source.copy();
+    assertThat(copy.toString()).isEqualTo(source.toString());
+
+    copy.add("canMutate");
+    assertThat(copy.size()).isEqualTo(3);
+    assertThat(source.size()).isEqualTo(2);
+  }
+
+  @Test
+  void unmodifiable() {
+    final JsonArray source = JsonArray.create()
+            .add("foo")
+            .add(JsonObject.create().add("b", 42));
+
+    JsonArray copy = source.unmodifiable();
+    assertThat(copy.toString()).isEqualTo(source.toString());
+
+    assertThatThrownBy(() -> copy.add("canMutate"))
+            .isInstanceOf(UnsupportedOperationException.class);
+  }
+
 }