TokenVariable.java

/*
 * This file is part of the URI Template library.
 *
 * For licensing information please see the file license.txt included in the release.
 * A copy of this licence can also be found at 
 *   http://www.opensource.org/licenses/artistic-license-2.0.php
 */
package org.weborganic.furi;


import java.util.Map;
import java.util.regex.Pattern;

import org.weborganic.furi.URICoder;


/**
 * A URI token wrapping a variable.
 * 
 * <p>Variables follow the following expression:
 * <pre>
 * var         = varname [ "=" vardefault ]
 * varname     = (ALPHA / DIGIT)*(ALPHA / DIGIT / "." / "_" / "-" )
 * vardefault  = *(unreserved / pct-encoded)
 * </pre>
 * 
 * @author Christophe Lauret
 * @version 30 December 2008
 */
public class TokenVariable extends TokenBase implements Token, Matchable {

    /**
     * The variable for this token.
     */
    private Variable _var;

    /**
     * Creates a new variable token.
     * 
     * @param exp The expression to create a new.
     * 
     * @throws NullPointerException If the specified expression is <code>null</code>.
     * @throws URITemplateSyntaxException If the specified expression could not be parsed as a
     *           variable.
     */
    public TokenVariable(String exp) throws NullPointerException, URITemplateSyntaxException {
        this(Variable.parse(exp));
    }

    /**
     * Creates a new variable token.
     * 
     * @param var The variable this token corresponds to.
     * 
     * @throws NullPointerException If the specified text is <code>null</code>.
     */
    public TokenVariable(Variable var) throws NullPointerException {
        super('{' + var.toString() + "}");
        this._var = var;
    }

    /**
     * Returns the variable wrapped by this token.
     * 
     * @return The variable wrapped by this token.
     */
    public Variable getVariable() {
        return _var;
    }

    /**
     * {@inheritDoc}
     */
    public String expand(Parameters variables) {
        return URICoder.encode(this._var.value(variables));
    }

    /**
     * {@inheritDoc}
     */
    public boolean match(String value) {
        return Variable.isValidValue(value);
    }

    /**
     * {@inheritDoc}
     */
    public Pattern pattern() {
        return Variable.VALID_VALUE;
    }

    /**
     * {@inheritDoc}
     */
    public boolean resolve(String expanded, Map<Variable, Object> values) {
        values.put(this._var, URICoder.decode(expanded));
        return true;
    }

}