com.github.fge.jsonschema.tree.JsonTree Maven / Gradle / Ivy

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/*
 * Copyright (c) 2013, Francis Galiegue 
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the Lesser GNU General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * Lesser GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */

package com.github.fge.jsonschema.tree;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.MissingNode;
import com.github.fge.jsonschema.ref.JsonPointer;
import com.github.fge.jsonschema.util.AsJson;

/**
 * A JSON value decorated with JSON Pointer information
 *
 * This is a {@link JsonNode} with an internal, modifiable path represented
 * as a {@link JsonPointer}. The current path and node are retrievable.
 *
 * There are two operations to modify the current path:
 *
 * 
 *     {@link #append(JsonPointer)} will append a pointer to the current
 *     path (like a relative {@code cd});
 *     {@link #pop()} will get back to the previous path.
 * 
 *
 * An initialized tree always starts at the root of the wrapped JSON
 * document. If the current pointer points to a non existent path in the
 * document, the retrieved node is a {@link MissingNode}.
 *
 * Finally, remember that JSON Pointers are always absolute, which
 * means that appending {@code ..} over {@code /a/b} will not lead to {@code
 * /a}, but {@code /a/b/..}. {@code ..} is a perfectly valid member name for
 * a JSON Object!
 *
 * @see JsonPointer
 */
public interface JsonTree
    extends AsJson
{
    /**
     * Return the node this tree was created with
     *
     * Note: in current Jackson versions, this node is unfortunately mutable,
     * so be careful...
     *
     * @return the node
     */
    JsonNode getBaseNode();
    /**
     * Append a JSON Pointer to the current path
     *
     * @param ptr the pointer to append
     * @see JsonPointer#append(JsonPointer)
     */
    void append(final JsonPointer ptr);

    /**
     * Reverts the last append
     *
     * Note: this operation will fail badly if you haven't appended anything,
     * so use with care!
     */
    void pop();

    /**
     * Get the current path into the document
     *
     * @return the path as a JSON Pointer
     */
    JsonPointer getCurrentPointer();

    /**
     * Get the node at the current path
     *
     * @return the matching node (a {@link MissingNode} if there is no matching
     * node at that pointer)
     */
    JsonNode getCurrentNode();
}