com.github.fge.jsonschema.main.Keyword 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.main;

import com.github.fge.jsonschema.old.keyword.KeywordValidator;
import com.github.fge.jsonschema.metaschema.KeywordRegistry;
import com.github.fge.jsonschema.old.syntax.SyntaxChecker;
import com.google.common.base.Preconditions;

/**
 * Representation of a schema keyword: its name, syntax checker and validator
 *
 * The process is as follows:
 *
 * 
 *     choose the name of the new keyword;
 *     create a {@link SyntaxChecker} for this keyword;
 *     create a {@link KeywordValidator};
 *     create the keyword.
 * 
 *
 * It is perfectly legal to register a keyword with only a syntax checker, or
 * only a keyword validator. An example is {@code $schema}, which must be a
 * valid URI (therefore it has a syntax checker) but does not play any role
 * in instance validation (therefore it has no keyword validator).
 *
 * This class is thread safe and immutable.
 *
 * @see Keyword.Builder
 * @see SyntaxChecker
 * @see KeywordValidator
 * @see KeywordRegistry
 */
public final class Keyword
{
    private final String name;
    private final SyntaxChecker syntaxChecker;
    private final Class validatorClass;

    private Keyword(final Builder builder)
    {
        name = builder.keyword;
        syntaxChecker = builder.syntaxChecker;
        validatorClass = builder.validatorClass;
    }

    /**
     * Create a new {@link Builder} for a keyword with a given name
     *
     * @param name the name
     * @return the newly created builder
     */
    public static Keyword.Builder withName(final String name)
    {
        return new Builder(name);
    }

    public String getName()
    {
        return name;
    }

    public SyntaxChecker getSyntaxChecker()
    {
        return syntaxChecker;
    }

    public Class getValidatorClass()
    {
        return validatorClass;
    }

    /**
     * Builder class for a new keyword
     */
    public static final class Builder
    {
        private final String keyword;
        private SyntaxChecker syntaxChecker;
        private Class validatorClass;

        /**
         * The only constructor, private by design
         *
         * @param keyword the keyword name
         * @throws NullPointerException the keyword name is null (illegal)
         */
        private Builder(final String keyword)
        {
            Preconditions.checkNotNull(keyword, "keyword name must not be null");
            this.keyword = keyword;
        }

        /**
         * Add a syntax checker to this keyword
         *
         * @param syntaxChecker the syntax checker, already instantiated
         * @return this
         */
        public Builder withSyntaxChecker(final SyntaxChecker syntaxChecker)
        {
            this.syntaxChecker = syntaxChecker;
            return this;
        }

        /**
         * Add the keyword validator class
         *
         * We add the class, not an instance, since the generated object is
         * dependent on the schema being passed.
         *
         * @param validatorClass the class
         * @return this
         */
        public Builder withValidatorClass(
            final Class validatorClass)
        {
            this.validatorClass = validatorClass;
            return this;
        }

        /**
         * Build the {@link Keyword}
         *
         * @return the keyword
         */
        public Keyword build()
        {
            return new Keyword(this);
        }
    }
}