com.github.fge.jsonschema.validator.ValidationContext Maven / Gradle / Ivy

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/*
 * Copyright (c) 2012, 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.validator;

import com.fasterxml.jackson.databind.JsonNode;
import com.github.fge.jsonschema.format.FormatAttribute;
import com.github.fge.jsonschema.ref.JsonRef;
import com.github.fge.jsonschema.schema.SchemaContext;
import com.github.fge.jsonschema.schema.SchemaNode;
import com.github.fge.jsonschema.util.jackson.JacksonUtils;
import com.google.common.collect.Queues;

import java.net.URI;
import java.util.Deque;

/**
 * A validation context
 *
 * This object is passed along the validation process. At any point in the
 * validation process, it contains the current schema context, the feature set
 * and the validator cache.
 *
 * The latter is necessary since four keywords may have to spawn other
 * validators: {@code type}, {@code disallow}, {@code dependencies} and {@code
 * extends}.
 *
 * One instance is created for each validation and is passed around to all
 * validators. Due to this particular usage, it is not thread safe.
 */
public final class ValidationContext
{
    private static final SchemaContext DUMMY_CONTEXT
        = new SchemaContext(URI.create("#"),
        JacksonUtils.nodeFactory().nullNode())
    {
        @Override
        public boolean contains(final JsonRef other)
        {
            throw new RuntimeException("How did I get there??");
        }

        @Override
        public JsonNode resolve(final JsonRef ref)
        {
            throw new RuntimeException("How did I get there??");
        }
    };

    private final JsonValidatorCache cache;
    private final Deque contextQueue = Queues.newArrayDeque();

    private SchemaContext currentContext = DUMMY_CONTEXT;

    /**
     * Create a validation context with an empty feature set
     *
     * @param cache the validator cache to use
     */
    public ValidationContext(final JsonValidatorCache cache)
    {
        this.cache = cache;
    }

    void pushContext(final SchemaContext context)
    {
        contextQueue.push(currentContext);
        currentContext = context;
    }

    void popContext()
    {
        currentContext = contextQueue.pop();
    }

    /**
     * Return a format attribute for a given attribute
     *
     * @param fmt the format attribute
     * @return the attribute, {@code null} if not found
     */
    public FormatAttribute getFormat(final String fmt)
    {
        return cache.getFormatAttributes().get(fmt);
    }

    /**
     * Build a new validator out of a JSON document
     *
     * This calls {@link JsonValidatorCache#getValidator(SchemaNode)} with
     * this context's {@link SchemaContext} used as a schema context.
     *
     * @param node the node (a subnode of the schema)
     * @return a validator
     */
    public JsonValidator newValidator(final JsonNode node)
    {
        final SchemaNode schemaNode = new SchemaNode(currentContext, node);
        return cache.getValidator(schemaNode);
    }

    @Override
    public String toString()
    {
        return "current: " + currentContext;
    }
}