com.github.jknack.handlebars.JsonNodeValueResolver.java Source code

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Here is the source code for com.github.jknack.handlebars.JsonNodeValueResolver.java

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/**
 * Copyright (c) 2012-2013 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.Collections;
import java.util.Iterator;
import java.util.LinkedHashMap;
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 {
                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 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();
        }
        // container, array or null
        return node;
    }

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

}