com.github.jknack.handlebars.JsonNodeValueResolver Maven / Gradle / Ivy

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/**
 * Copyright (c) 2012-2015 Edgar Espina
 *
 * This file is part of Handlebars.java.
 *
 * 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.
 */
package com.github.jknack.handlebars;

import java.util.AbstractMap;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.BigIntegerNode;
import com.fasterxml.jackson.databind.node.BinaryNode;
import com.fasterxml.jackson.databind.node.BooleanNode;
import com.fasterxml.jackson.databind.node.DecimalNode;
import com.fasterxml.jackson.databind.node.DoubleNode;
import com.fasterxml.jackson.databind.node.IntNode;
import com.fasterxml.jackson.databind.node.LongNode;
import com.fasterxml.jackson.databind.node.NullNode;
import com.fasterxml.jackson.databind.node.ObjectNode;
import com.fasterxml.jackson.databind.node.POJONode;
import com.fasterxml.jackson.databind.node.TextNode;

/**
 * Resolve a context stack value from {@link JsonNode}.
 *
 * @author edgar.espina
 * @since 0.9.0
 */
public enum JsonNodeValueResolver implements ValueResolver {

  /**
   * The singleton instance.
   */
  INSTANCE;

  @Override
  public Object resolve(final Object context, final String name) {
    Object value = null;
    if (context instanceof ArrayNode) {
      try {
        if (name.equals("length")) {
          return ((ArrayNode) context).size();
        }
        value = resolve(((ArrayNode) context).get(Integer.parseInt(name)));
      } catch (NumberFormatException ex) {
        // ignore undefined key and move on, see https://github.com/jknack/handlebars.java/pull/280
        value = null;
      }
    } else if (context instanceof JsonNode) {
      value = resolve(((JsonNode) context).get(name));
    }
    return value == null ? UNRESOLVED : value;
  }

  @Override
  public Object resolve(final Object context) {
    if (context instanceof JsonNode) {
      return resolve((JsonNode) context);
    }
    return UNRESOLVED;
  }

  /**
   * Resolve a {@link JsonNode} object to a primitive value.
   *
   * @param node A {@link JsonNode} object.
   * @return A primitive value, json object, json array or null.
   */
  private static Object resolve(final JsonNode node) {
    // binary node
    if (node instanceof BinaryNode) {
      return ((BinaryNode) node).binaryValue();
    }
    // boolean node
    if (node instanceof BooleanNode) {
      return ((BooleanNode) node).booleanValue();
    }
    // null node
    if (node instanceof NullNode) {
      return null;
    }
    // numeric nodes
    if (node instanceof BigIntegerNode) {
      return ((BigIntegerNode) node).bigIntegerValue();
    }
    if (node instanceof DecimalNode) {
      return ((DecimalNode) node).decimalValue();
    }
    if (node instanceof DoubleNode) {
      return ((DoubleNode) node).doubleValue();
    }
    if (node instanceof IntNode) {
      return ((IntNode) node).intValue();
    }
    if (node instanceof LongNode) {
      return ((LongNode) node).longValue();
    }
    // pojo
    if (node instanceof POJONode) {
      return ((POJONode) node).getPojo();
    }
    // string
    if (node instanceof TextNode) {
      return ((TextNode) node).textValue();
    }
    // object node to map
    if (node instanceof ObjectNode) {
      return toMap((ObjectNode) node);
    }
    // container, array or null
    return node;
  }

  /**
   * @param node A json node.
   * @return A map from a json node.
   */
  private static Map toMap(final ObjectNode node) {
    return new AbstractMap() {
      @Override
      public Object get(final Object key) {
        return resolve(node.get((String) key));
      }

      @Override
      public int size() {
        return node.size();
      }

      @SuppressWarnings({"unchecked", "rawtypes" })
      @Override
      public Set> entrySet() {
        Iterator> it = node.fields();
        Set set = new LinkedHashSet();
        while (it.hasNext()) {
          set.add(it.next());
        }
        return set;
      }
    };
  }

  @Override
  public Set> propertySet(final Object context) {
    if (context instanceof ObjectNode) {
      ObjectNode node = (ObjectNode) context;
      Iterator fieldNames = node.fieldNames();
      Map result = new LinkedHashMap();
      while (fieldNames.hasNext()) {
        String key = fieldNames.next();
        result.put(key, resolve(node, key));
      }
      return result.entrySet();
    }
    return Collections.emptySet();
  }

}