Implement #790: external JsonNode comparator

Author: cowtowncoder

release-notes/VERSION

@@ -38,6 +38,8 @@ Project: jackson-databind
 #781: Support handling of `@JsonProperty.required` for Creator methods
 #787: Add `ObjectMapper setFilterProvider(FilterProvider)` to allow chaining
  (suggested by rgoldberg@githin)
+#790: Add `JsonNode.equals(Comparator<JsonNode>, JsonNode)` to support
+  configurable/external equality comparison
 - Remove old cglib compatibility tests; cause problems in Eclipse
 
 2.5.4 (not yet released)

src/main/java/com/fasterxml/jackson/databind/JsonNode.java

@@ -897,6 +897,34 @@ public JsonNode withArray(String propertyName) {
                 +getClass().getName()+"), can not call withArray() on it");
     }
 
+    /*
+    /**********************************************************
+    /* Public API, comparison
+    /**********************************************************
+     */
+
+    /**
+     * Entry method for invoking customizable comparison, using passed-in
+     * {@link Comparator} object. Nodes will handle traversal of structured
+     * types (arrays, objects), but defer to comparator for scalar value
+     * comparisons. If a "natural" {@link Comparator} is passed -- one that
+     * simply calls <code>equals()</code> on one of arguments, passing the other
+     * -- implementation is the same as directly calling <code>equals()<code>
+     * on node.
+     *<p>
+     * Default implementation simply delegates to passed in <code>comparator</code>,
+     * with <code>this</code> as the first argument, and <code>other</code> as
+     * the second argument.
+     * 
+     * @param comparator Object called to compare two scalar {@link JsonNode} 
+     *   instances, and return either 0 (are equals) or non-zero (not equal)
+     *
+     * @since 2.6
+     */
+    public boolean equals(Comparator<JsonNode> comparator, JsonNode other) {
+        return comparator.compare(this, other) == 0;
+    }
+    
     /*
     /**********************************************************
     /* Overridden standard methods

src/main/java/com/fasterxml/jackson/databind/ObjectMapper.java

@@ -1137,7 +1137,8 @@ public VisibilityChecker<?> getVisibilityChecker() {
 
     /**
      * @deprecated Since 2.6 use {@link #setVisibility(VisibilityChecker)} instead.
-     */    
+     */
+    @Deprecated
     public void setVisibilityChecker(VisibilityChecker<?> vc) {
         setVisibility(vc);
     }

src/main/java/com/fasterxml/jackson/databind/node/ArrayNode.java

@@ -2,6 +2,7 @@
 
 import com.fasterxml.jackson.core.*;
 import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.JsonSerializable;
 import com.fasterxml.jackson.databind.SerializerProvider;
 import com.fasterxml.jackson.databind.jsontype.TypeSerializer;
 import com.fasterxml.jackson.databind.util.RawValue;
@@ -10,6 +11,7 @@
 import java.math.BigDecimal;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Comparator;
 import java.util.Iterator;
 import java.util.List;
 
@@ -98,30 +100,55 @@ public JsonNode path(int index) {
         }
         return MissingNode.getInstance();
     }
-    
+
+    @Override
+    public boolean equals(Comparator<JsonNode> comparator, JsonNode o)
+    {
+        if (!(o instanceof ArrayNode)) {
+            return false;
+        }
+        ArrayNode other = (ArrayNode) o;
+        final int len = _children.size();
+        if (other.size() != len) {
+            return false;
+        }
+        List<JsonNode> l1 = _children;
+        List<JsonNode> l2 = other._children;
+        for (int i = 0; i < len; ++i) {
+            if (comparator.compare(l1.get(i), l2.get(i)) != 0) {
+                return false;
+            }
+        }
+        return true;
+    }
+
     /*
     /**********************************************************
     /* Public API, serialization
     /**********************************************************
      */
 
     @Override
-    public void serialize(JsonGenerator jg, SerializerProvider provider) throws IOException, JsonProcessingException
+    public void serialize(JsonGenerator f, SerializerProvider provider) throws IOException
     {
-    	final List<JsonNode> c = _children;
-    	final int size = c.size();
-        jg.writeStartArray(size);
+        final List<JsonNode> c = _children;
+        final int size = c.size();
+        f.writeStartArray(size);
         for (int i = 0; i < size; ++i) { // we'll typically have array list
-        	// Can we trust that all nodes will always extend BaseJsonNode? Or if not,
-        	// at least implement JsonSerializable? Let's start with former, change if must
-            ((BaseJsonNode) c.get(i)).serialize(jg, provider);
+            // For now, assuming it's either BaseJsonNode, JsonSerializable
+            JsonNode n = c.get(i);
+            if (n instanceof BaseJsonNode) {
+                ((BaseJsonNode) n).serialize(f, provider);
+            } else {
+                ((JsonSerializable) n).serialize(f, provider);
+            }
         }
-        jg.writeEndArray();
+        f.writeEndArray();
     }
 
     @Override
     public void serializeWithType(JsonGenerator jg, SerializerProvider provider, TypeSerializer typeSer)
-        throws IOException, JsonProcessingException
+        throws IOException
     {
         typeSer.writeTypePrefixForArray(this, jg);
         for (JsonNode n : _children) {

src/main/java/com/fasterxml/jackson/databind/node/ObjectNode.java

@@ -10,6 +10,7 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Comparator;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.List;
@@ -163,7 +164,31 @@ public ArrayNode withArray(String propertyName)
         _children.put(propertyName, result);
         return result;
     }
-    
+
+    @Override
+    public boolean equals(Comparator<JsonNode> comparator, JsonNode o)
+    {
+        if (!(o instanceof ObjectNode)) {
+            return false;
+        }
+        ObjectNode other = (ObjectNode) o;
+        Map<String, JsonNode> m1 = _children;
+        Map<String, JsonNode> m2 = other._children;
+
+        final int len = m1.size();
+        if (m2.size() != len) {
+            return false;
+        }
+
+        for (Map.Entry<String, JsonNode> entry : m1.entrySet()) {
+            JsonNode v2 = m2.get(entry.getKey());
+            if ((v2 == null) || comparator.compare(entry.getValue(), v2) != 0) {
+                return false;
+            }
+        }
+        return true;
+    }
+
     /*
     /**********************************************************
     /* Public API, finding value nodes

src/test/java/com/fasterxml/jackson/databind/filter/TestJsonFilter.java

@@ -76,7 +76,7 @@ public void testSimpleInclusionFilter() throws Exception
 
         // [JACKSON-504]: also verify it works via mapper
         ObjectMapper mapper = new ObjectMapper();
-        mapper.setFilters(prov);
+        mapper.setFilterProvider(prov);
         assertEquals("{\"a\":\"a\"}", mapper.writeValueAsString(new Bean()));
     }
 
@@ -101,7 +101,7 @@ public void testMissingFilter() throws Exception
         // but when changing behavior, should work difference
         SimpleFilterProvider fp = new SimpleFilterProvider().setFailOnUnknownId(false);
         ObjectMapper mapper = new ObjectMapper();
-        mapper.setFilters(fp);
+        mapper.setFilterProvider(fp);
         String json = mapper.writeValueAsString(new Bean());
         assertEquals("{\"a\":\"a\",\"b\":\"b\"}", json);
     }

src/test/java/com/fasterxml/jackson/databind/introspect/TestAutoDetect.java

@@ -35,7 +35,7 @@ public void testPrivateCtor() throws Exception
         // note: clumsy code, but needed for Eclipse/JDK1.5 compilation (not for 1.6)
         VisibilityChecker<?> vc = m.getVisibilityChecker();
         vc = vc.withCreatorVisibility(JsonAutoDetect.Visibility.PUBLIC_ONLY);
-        m.setVisibilityChecker(vc);
+        m.setVisibility(vc);
         try {
             m.readValue("\"abc\"", PrivateBean.class);
             fail("Expected exception for missing constructor");

src/test/java/com/fasterxml/jackson/databind/node/TestJsonNode.java

@@ -1,5 +1,7 @@
 package com.fasterxml.jackson.databind.node;
 
+import java.util.Comparator;
+
 import com.fasterxml.jackson.core.*;
 import com.fasterxml.jackson.core.io.SerializedString;
 import com.fasterxml.jackson.databind.*;
@@ -120,4 +122,42 @@ public void testRawValue() throws Exception
 
         assertEquals("{\"a\":[1, 2, 3]}", MAPPER.writeValueAsString(root));
     }
+
+    // [databind#790]
+    public void testCustomComparators() throws Exception
+    {
+        ObjectNode root1 = MAPPER.createObjectNode();
+        root1.put("value", 5);
+        ObjectNode root2 = MAPPER.createObjectNode();
+        root2.put("value", 5.0);
+
+        // default equals(): not strictly equal
+        assertFalse(root1.equals(root2));
+        assertFalse(root2.equals(root1));
+        assertTrue(root1.equals(root1));
+        assertTrue(root2.equals(root2));
+
+        // but. Custom comparator can make all the difference
+        Comparator<JsonNode> cmp = new Comparator<JsonNode>() {
+
+            @Override
+            public int compare(JsonNode o1, JsonNode o2) {
+                if (o1.equals(o2)) {
+                    return 0;
+                }
+                if ((o1 instanceof NumericNode) && (o2 instanceof NumericNode)) {
+                    double d1 = ((NumericNode) o1).asDouble();
+                    double d2 = ((NumericNode) o2).asDouble();
+                    if (d1 == d2) { // strictly equals because it's integral value
+                        return 1;
+                    }
+                }
+                return 0;
+            }
+        };
+        assertTrue(root1.equals(cmp, root2));
+        assertTrue(root2.equals(cmp, root1));
+        assertTrue(root1.equals(cmp, root1));
+        assertTrue(root2.equals(cmp, root2));
+    }
 }

src/test/java/com/fasterxml/jackson/databind/ser/TestAutoDetect.java

@@ -74,7 +74,7 @@ public void testPrivateUsingGlobals() throws Exception
         ObjectMapper m = new ObjectMapper();
         VisibilityChecker<?> vc = m.getVisibilityChecker();
         vc = vc.withFieldVisibility(JsonAutoDetect.Visibility.ANY);
-        m.setVisibilityChecker(vc);
+        m.setVisibility(vc);
 
         Map<String,Object> result = writeAndMap(m, new FieldBean());
         assertEquals(3, result.size());
@@ -85,7 +85,7 @@ public void testPrivateUsingGlobals() throws Exception
         m = new ObjectMapper();
         vc = m.getVisibilityChecker();
         vc = vc.withGetterVisibility(JsonAutoDetect.Visibility.ANY);
-        m.setVisibilityChecker(vc);
+        m.setVisibility(vc);
         result = writeAndMap(m, new MethodBean());
         assertEquals(3, result.size());
         assertEquals("a", result.get("a"));
@@ -99,7 +99,7 @@ public void testBasicSetup() throws Exception
         ObjectMapper m = new ObjectMapper();
         VisibilityChecker<?> vc = m.getVisibilityChecker();
         vc = vc.with(JsonAutoDetect.Visibility.ANY);
-        m.setVisibilityChecker(vc);
+        m.setVisibility(vc);
 
         Map<String,Object> result = writeAndMap(m, new FieldBean());
         assertEquals(3, result.size());