MapVariableInterpolator.java

/**
 *  Copyright 2012 Universitat Pompeu Fabra.
 *
 *  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 org.onexus.resource.api.utils.string;

import java.util.Map;

/**
 * Original code extract from Apache Wicket core *
 */
public class MapVariableInterpolator extends VariableInterpolator {
    /**
     * Map of variables
     */
    private Map<?, ?> variables;

    /**
     * Constructor.
     *
     * @param string    a <code>String</code> to interpolate into
     * @param variables the variables to substitute
     */
    public MapVariableInterpolator(final String string, final Map<?, ?> variables) {
        super(string);
        this.variables = variables;
    }

    /**
     * Constructor.
     *
     * @param string                  a <code>String</code> to interpolate into
     * @param variables               the variables to substitute
     * @param exceptionOnNullVarValue if <code>true</code> an {@link IllegalStateException} will be thrown if
     *                                {@link #getValue(String)} returns <code>null</code>, otherwise the
     *                                <code>${varname}</code> string will be left in the <code>String</code> so that
     *                                multiple interpolators can be chained
     */
    public MapVariableInterpolator(final String string, final Map<?, ?> variables,
                                   final boolean exceptionOnNullVarValue) {
        super(string, exceptionOnNullVarValue);
        this.variables = variables;
    }

    /**
     * Sets the <code>Map</code> of variables.
     *
     * @param variables the <code>Map</code> of variables
     */
    public final void setVariables(final Map<?, ?> variables) {
        this.variables = variables;
    }

    /**
     * Retrieves a value for a variable name during interpolation.
     *
     * @param variableName the variable name
     * @return the value
     */
    @Override
    protected String getValue(final String variableName) {
        Object value = variables.get(variableName);

        if (value == null) {
            return null;
        }

        return value.toString();
    }

    /**
     * Interpolates a <code>String</code> with the arguments defined in the given <code>Map</code>.
     *
     * @param string    a <code>String</code> to interpolate into
     * @param variables the variables to substitute
     * @return the interpolated <code>String</code>
     */
    public static String interpolate(final String string, final Map<?, ?> variables) {
        return new MapVariableInterpolator(string, variables).toString();
    }

}